JP6858365B2 - Manufacturing method of gas flow sputtering equipment, gas flow sputtering target and sputtering target raw material - Google Patents

Description

The present invention relates to a gas flow sputtering apparatus, a target for gas flow sputtering, and a method for producing a raw material for a sputtering target.

In the field of magnetic recording represented by a hard disk drive, a material based on the ferromagnetic metals Co, Fe, or Ni is used as the material of the magnetic thin film responsible for recording. For example, a Co-Cr-based or Co-Cr-Pt-based ferromagnetic alloy containing Co as a main component has been used for the recording layer of a hard disk adopting the in-plane magnetic recording method. Further, in the recording layer of a hard disk adopting a perpendicular magnetic recording method that has been put into practical use in recent years, non-magnetic particles such as oxides and carbon are dispersed in a Co-Cr-Pt-based ferromagnetic alloy containing Co as a main component. Composite materials are often used.

A magnetic thin film of a magnetic recording medium such as a hard disk is often produced by sputtering a sputtering target containing the above-mentioned material as a component because of its high productivity. In the non-magnetic material particle dispersion type sputtering target, the contained non-magnetic particles cause an abnormal discharge during sputtering, and the abnormal discharge causes particles to be generated. In recent years, as the recording capacity of hard disk drives has increased, there has been an increasing need to reduce particles from sputtering targets when manufacturing hard disk media.

Sputtering targets are generally manufactured by the powder sintering method. It is known that miniaturization of non-magnetic particles in a sputtering target is very effective for reducing particles. For that purpose, one of the effective methods is to mechanically pulverize and mix the raw material powders with each other using a powerful ball mill or the like. However, with the current method of mechanically pulverizing and mixing, there is a physical limit to the miniaturization of the structure, and it is difficult to completely eliminate the generation of particles.

Therefore, in International Publication No. 2013/136962, it is proposed to refine the oxide by using PVD or CVD method instead of the conventional mechanical pulverization and mixing. Specifically, a method is described in which a magnetic material is formed on a substrate by a PVD or CVD method, the substrate is removed from the formed magnetic material, and the substrate is pulverized to be used as a raw material. According to the technique, it is described that the average particle size of the oxide in the sputtering target can be miniaturized to 400 nm or less. In the examples of the document, it is described that the target raw material is formed by using a DC magnetron sputtering apparatus.

On the other hand, as a sputtering method, a gas flow sputtering method is also known (eg, JP-A-2006-130378, JP-A-2007-186771 and JP-A-2008-1957). The gas flow sputtering method is a method in which sputtering is performed under a relatively high pressure, and sputtered particles are transported to a substrate to be filmed by a forced flow of gas and deposited. Since this gas flow sputtering method does not require high vacuum exhaust, it is possible to form a film with mechanical pump exhaust without using a large-scale exhaust device like the conventional ordinary sputtering method, and it is inexpensive. It can be carried out with various equipment. Moreover, the gas flow sputtering method can form a film at a speed 10 to 1000 times higher than that of the normal sputtering method. Therefore, according to the gas flow sputtering method, it is possible to reduce the film forming cost by reducing the equipment cost and the film forming time.

International Publication No. 2013/136962 Japanese Unexamined Patent Publication No. 2006-13378 Japanese Unexamined Patent Publication No. 2007-186771 Japanese Unexamined Patent Publication No. 2008-1957

The invention described in International Publication No. 2013/136962 is an effective technique for microstructuring a non-magnetic material particle-dispersed sputtering target, but is used by PVD or CVD method on a substrate to produce a raw material for the sputtering target. It is necessary to carry out the step of forming a film. For this purpose, if a film is formed using a high-performance device such as a DC magnetron sputtering device, there is a problem that the manufacturing cost of the sputtering target is high and the productivity is also low. In this respect, since the gas flow sputtering method enables high-speed film formation and the equipment cost is low, it is considered advantageous if the raw material of the sputtering target can be produced by using the gas flow sputtering method.

However, no attempt has been made to produce a raw material for a sputtering target using the gas flow sputtering method. Patent Documents 2 to 4 describe a catalyst layer of an electrode for a polymer electrolyte fuel cell, a semiconductor electrode layer for a dye-sensitized solar cell, a photocatalyst film, an antireflection film, an electrochromic element, and a transparent conductive film by a gas flow sputtering method. It is only stated that it is manufactured. Therefore, in the prior art, the apparatus has not been improved from the viewpoint of industrially producing the raw material of the sputtering target. In particular, in order to use it as a raw material for a sputtering target, a large amount of raw material is required, so that it is necessary to perform stable continuous sputtering for a long time, and there is still room for improvement from the viewpoint of the equipment configuration and manufacturing method for that purpose. Has been done.

The present invention has been created in view of the above circumstances, and one of the problems of the present invention is to provide a gas flow sputtering apparatus suitable for producing a sputtering target raw material stably for a long time at a high sputtering rate. To do. Another object of the present invention is to provide a target for gas flow sputtering. Another object of the present invention is to provide a method for producing a raw material for a sputtering target using the gas flow sputtering apparatus.

As a result of diligent studies to solve the above problems, the present inventor has almost no problem in film thickness uniformity and surface texture of the sputtering film formed by the gas flow sputtering apparatus for the purpose of producing the raw material of the sputtering target. It does not become. Therefore, for this purpose, it is more important to suppress abnormal discharge at a high sputtering rate than to improve the quality of the sputtering film. Based on this viewpoint, the present inventor has found that a gas flow sputtering apparatus having the following configuration using a flat plate facing type target is effective.

In one aspect, the present invention
A sputtering chamber that can evacuate the inside and
A pair of flat plate targets arranged so that the sputtering surfaces face each other at intervals in the sputtering chamber.
One or more gas outlets for supplying sputter gas between the pair of flat plate targets, and
An exhaust port for exhausting spatter gas and
A member that deposits sputter particles arranged so as to face the gas discharge port on the opposite side of the space between the pair of flat plate targets and the gas discharge port.
An interval adjustment mechanism that enables the interval adjustment of the pair of flat plate targets,
It is a gas flow sputtering apparatus equipped with.

In one embodiment of the gas flow sputtering apparatus according to the present invention, a position adjusting mechanism capable of relatively adjusting the positions of the one or more gas discharge ports and the pair of flat plate targets is provided. It is a gas flow sputtering apparatus provided.

Another embodiment of the gas flow sputtering apparatus according to the present invention includes a flow rate adjusting mechanism for adjusting the flow rate of the sputtered gas supplied from the one or more gas discharge ports.

Yet another embodiment of the gas flow sputtering apparatus according to the present invention includes two or more gas discharge ports.

In yet another embodiment of the gas flow sputtering apparatus according to the present invention, one or more gas discharge units in which two or more gas discharge ports are arranged are provided.

In yet another embodiment of the gas flow sputtering apparatus according to the present invention, the interval adjusting mechanism is installed outside the sputtering chamber.

In yet another embodiment of the gas flow sputtering apparatus according to the present invention, a part of the inside of the sputtering chamber has an atmospheric blocking performance arranged so as to expand and contract according to the operation of the interval adjusting mechanism. The elastic member having the elastic member defines the boundary with the outside.

In yet another embodiment of the gas flow sputtering apparatus according to the present invention, the interval adjusting mechanism has a manually operable drive mechanism connected to at least one of the pair of flat plate targets.

In yet another embodiment of the gas flow sputtering apparatus according to the present invention, the interval adjusting mechanism has a motor drive mechanism connected to at least one of the pair of flat plate targets.

In yet another embodiment of the gas flow sputtering apparatus according to the present invention, the interval adjusting mechanism is configured so that the interval between the pair of flat plate targets can be adjusted at least based on the discharge time and the integrated power.

In yet another embodiment of the gas flow sputtering apparatus according to the present invention, the interval adjusting mechanism is configured such that the change width of the average interval of the pair of flat plate targets during the sputtering process is 5 mm or less.

In yet another embodiment of the gas flow sputtering apparatus according to the present invention, the distance between the pair of flat plate targets before the start of sputtering is 10 to 100 mm.

In yet another embodiment of the gas flow sputtering apparatus according to the present invention, the total projected area of the facing surfaces of the pair of flat plate targets is 300 cm ² or more.

In still another embodiment of the gas flow sputtering apparatus according to the present invention, electric discharge can be performed under the condition that ^{the power density is 10 W / cm 2 or more.}

In yet another embodiment of the gas flow sputtering apparatus according to the present invention, the pair of flat plate targets is composed of a composite of a non-magnetic material and a magnetic material.

In another aspect, the present invention is a gas flow sputtering target composed of a composite of a non-magnetic material and a magnetic material.

In yet another aspect, the present invention is a method for producing a sputtering target raw material, which comprises a step of sputtering using the gas flow sputtering apparatus according to the present invention.

In one embodiment of the method for producing a sputtering target raw material according to the present invention, sputtering is performed at a power density of 10 W / cm ² or more.

In another embodiment of the method for producing a sputtering target raw material according to the present invention, the flow rate of the sputtering gas is expressed as the flow rate per ^{1 cm 2 of the total projected area of the opposing sputtering surfaces of the pair of flat plate targets, and is 1 sccm / cm 2} or more. Sputter as.

In yet another embodiment of the method for producing a sputtering target raw material according to the present invention, the sputtering gas is sputtered at a pressure of 10 Pa or more.

In yet another embodiment of the method for producing a sputtering target raw material according to the present invention, the interval adjusting mechanism is operated so that the change in the average interval between the pair of flat plate targets from the start of sputtering to the end of sputtering is 5 mm or less. Including that.

In yet another embodiment of the method for producing a raw material for a sputtering target according to the present invention, the member for depositing the sputtered particles is a used sputtering target, and the sputtered particles are deposited on the eroded portion of the target.

In another embodiment of the gas flow sputtering target according to the present invention, a backing plate is provided, and the backing plate is bonded to the backing plate with a heat-resistant adhesive at 200 ° C. or higher.

In yet another embodiment of the gas flow sputtering target according to the present invention, a backing plate is provided and diffusion-bonded to the backing plate.

According to the present invention, when the sputtering target raw material is manufactured by using the gas flow sputtering apparatus, abnormal discharge is less likely to occur, so that it is possible to continuously and stably sputter for a long time. This makes it possible to produce a raw material for a sputtering target, particularly a raw material for a non-magnetic material particle-dispersed sputtering target having a finer structure, with higher production efficiency and lower cost than in the prior art.

It is a schematic diagram which shows an example of the basic structure inside the gas flow sputtering apparatus which concerns on this invention. It is a schematic diagram which shows an example of the schematic equipment structure of the gas flow sputtering apparatus which concerns on this invention. It is a schematic diagram which shows another example of the schematic equipment structure of the gas flow sputtering apparatus which concerns on this invention. It is a schematic diagram which shows still another example of the schematic equipment structure of the gas flow sputtering apparatus which concerns on this invention. It is a schematic diagram which shows the 1st example of the cross-sectional structure around the gas flow sputtering target and the fixing member which concerns on this invention (the backing plate is not used). It is a schematic diagram which shows the 2nd example of the cross-sectional structure around the gas flow sputtering target and the fixing member which concerns on this invention (the backing plate is not used). It is a schematic diagram which shows the 3rd example of the cross-sectional structure around the gas flow sputtering target and the fixing member which concerns on this invention (the backing plate is not used). It is a schematic diagram which shows the 4th example of the cross-sectional structure around the gas flow sputtering target and the fixing member which concerns on this invention (the backing plate is not used). It is a schematic diagram which shows the 5th example of the cross-sectional structure around the gas flow sputtering target and the fixing member which concerns on this invention (using a backing plate). An example of the arrangement of the flat plate target and the insulating shield member in a plan view when the flat plate target according to the present invention is fixed in the gas flow sputtering apparatus is shown. It is a schematic diagram which shows the structural example of the sputter gas discharge unit which has a plurality of gas discharge ports.

Hereinafter, various embodiments of the gas flow sputtering apparatus according to the present invention will be described in detail with reference to the drawings. FIG. 1 shows an example of the basic structure inside the gas flow sputtering apparatus according to the present invention, and FIGS. 2-1 to 2-3 show a schematic device configuration example of the gas flow sputtering apparatus according to the present invention. There is. In the sputtering chamber 11 where the inside can be evacuated (= less than atmospheric pressure), the sputtering surfaces of the pair of flat plate targets 10a and 10b are arranged so as to face each other at predetermined intervals. The pair of flat plate targets 10a and 10b can be arranged in parallel with each other in the state before the start of sputtering, so that the plasma density can be uniformly increased on the target surface without showing unexpected behavior. , Preferable from the viewpoint of being effective in improving the erosion speed. However, it is also possible to sputter the sputtering surfaces at an angle rather than parallel to each other. A negative voltage is applied to each of the targets 10a and 10b to generate plasma of a sputtering gas 17 such as Ar in the space 12 between the pair of flat plate targets 10a and 10b, and the plasma is made to collide with each target to cause the sputtered particles 13 to collide with each target. To generate.

FIGS. 2-1 to 2-3 show the exemplary potentials of each device during sputtering separately. It is necessary that the pair of flat plate targets 10a and 10b serve as cathode potentials during sputtering, but there are no particular restrictions on the potentials of other parts as long as the sputtering apparatus can be operated safely, but from the viewpoint of stable operation. Since there is a preferred embodiment, it will be described later. The outer wall of the sputtering chamber 11 is generally set to an anode potential for safety reasons. In general, an insulating member is effective when it is necessary to insulate between the anode potential portion and the cathode potential portion in a space other than the space.

As the power source of the gas flow sputtering apparatus, either a DC power source or an AC power source may be used, but the DC power source 15 is preferable because the cost of the power source device is low and the sputtering rate per unit time is fast. The generated sputter particles 13 flow in from the sputter gas discharge port 14, and ride on the forced gas flow of the sputter gas 17 flowing in the space 12 between the pair of flat plate targets 10a and 10b in the direction of the arrow, and the pair of flat plate targets 10a. A member 16 for depositing sputter particles 13 installed so as to face the sputter gas discharge port 14 outside the space 12 between 10b (the space surrounded by the one-point chain line in FIGS. 2-1 to 2-3). It is deposited on the surface (typically, the substrate to be deposited). In the present specification, the space between the pair of flat plate targets is formed by extending the contour of the sputtered surface of one flat plate target toward the normal direction of the sputtered surface and closer to the other flat plate target. Of the space surrounded by figures and the space surrounded by figures formed by extending the contour of the sputtered surface of the other flat plate target in the normal direction of the sputtered surface toward the side closer to one flat plate target. , Refers to the part where the two overlap. Further, in the present specification, when the member on which the sputter particles are deposited faces the sputter gas discharge port, the straight line extending from at least one sputter gas discharge port in the gas discharge direction and the surface on which the sputter particles are deposited are defined as each other. It means having an intersection. The member 16 on which the sputtered particles 13 are deposited can be supported by the holder 18. The holder 18 is installed on the opposite side of the sputter gas discharge port 14 via the space portion 12 sandwiched between the pair of flat plate targets 10a and 10b. The sputter gas 17 is then discharged from the exhaust port 20. The exhaust port 20 can be installed, for example, behind the holder 18 (in other words, on the back side). By installing the exhaust port 20 behind the holder 18, the sputter particles 13 accompanying the sputter gas 17 can be efficiently collided with the member 16.

In the gas flow sputtering method, the power density and the gas flow velocity can be increased as compared with the normal sputtering method, so that high-speed film formation becomes possible. However, if the power density is increased in order to perform high-speed film formation, abnormal discharge is likely to occur. This tendency is particularly remarkable when the target is composed of a material containing an insulating material such as an oxide. If an abnormal discharge occurs during sputtering, the parts near the abnormal discharge will be damaged and maintenance frequency will increase, or it will be necessary to stop the sputtering operation. Therefore, suppressing the abnormal discharge stabilizes the device for a long time. It is an important issue to operate. In order to suppress abnormal discharge, it is effective to shorten _{the interval (S 1} ) between the pair of flat plate targets 10a and 10b. Specifically, the distance between the pair of flat plate targets 10a and 10b before the start of sputtering is preferably 100 mm or less, more preferably 50 mm or less, even more preferably 45 mm or less, and 40 mm or less. It is even more preferable to have. _{On the other hand, if the interval (S 1} ) between the pair of flat plate targets 10a and 10b is made too short, the amount of gas carrying the sputtered particles 13 decreases and the sputtered particles 13 reattach to the target surface. It becomes difficult to efficiently deposit on the member 16 to be deposited. _{When shortening the interval (S 1} ) between the pair of flat plate targets 10a and 10b, a method of increasing the flow velocity of the sputtering gas passing between the pair of flat plate targets 10a and 10b to prevent the sputtering particles 13 from adhering to the surface of the opposing target can be considered. However, in that case, a large amount of sputter gas and a vacuum pump having a large exhaust capacity are required. From this viewpoint, the distance between the pair of flat plate targets 10a and 10b before the start of sputtering is preferably 10 mm or more, and more preferably 15 mm or more.

The thickness of the target becomes thinner due to erosion as the sputtering time increases. Therefore, the interval between the pair of flat plate targets 10a and 10b increases in conjunction with the sputtering time if no treatment is taken, and the voltage applied to the targets gradually increases, increasing the risk of causing abnormal discharge. To do. However, if the distance between the pair of flat plate targets 10a and 10b can be maintained in a certain range regardless of the thickness of the target, for example, in a suitable range of the distance between the pair of flat plate targets 10a and 10b described above, abnormal discharge will occur. It does not increase the risk of occurrence. Therefore, in one embodiment of the gas flow sputtering apparatus according to the present invention, when the pair of flat plate targets 10a and 10b are eroded by sputtering, the distance between the pair of flat plate targets can be maintained within a certain range. The interval adjusting mechanism 19 is provided so that a desired interval can be set at the start of sputtering. In FIG. 2, the pair of flat plate targets 10a and 10b are fixed to the cooling device 50 to form an integral structure component, and each integral structure component is movable by a corresponding interval adjusting mechanism 19.

The interval adjusting mechanism 19 is not particularly limited, and any known mechanism may be adopted. Examples thereof include a linear motion mechanism such as a cylinder linear motion mechanism and a ball screw linear motion mechanism. The drive system is not particularly limited, and examples thereof include motor drive, hydraulic drive, and air drive. From the viewpoint of enabling precise position adjustment, a linear motion mechanism driven by a motor is preferable. The interval between the pair of flat plate targets 10a and 10b may be automatically changed to a desired set value, or may be changed manually. Further, the change in the interval between the pair of flat plate targets 10a and 10b may be monitored during sputtering, and feedback control may be performed so that the initially set interval is maintained during sputtering. Feedback control may be manual or automatic. As a method of measuring the change in the interval between the pair of flat plate targets 10a and 10b, for example, a load cell is installed so that each weight of the flat plate targets 10a and 10b can be measured, and the weight reduction amount of the target and the density of the target are measured. And a method of calculating the average decrease amount of the target thickness (that is, the average increase amount of the interval between the targets) from the projected area of the sputtered surface. A calculator may be installed in the device so that the average reduction amount of the target thickness is calculated automatically, or the calculation result may be displayed on a display attached to the device. Further, for the flat plate targets 10a and 10b to be sputtered, the relationship between the discharge time and the integrated power and the average reduction amount of the target thickness is obtained in advance, and based on this, at least the average of the target thickness from the discharge time and the integrated power is obtained. A method of calculating the amount of decrease is also conceivable.

Then, by manually or automatically operating the interval adjusting mechanism 19 so that the average interval between the two targets is reduced by the amount corresponding to the sum of the average reduction amounts of the thicknesses of the targets 10a and 10b, a pair from the start to the end of sputtering is performed. It is possible to keep the distance between the flat plate targets 10a and 10b within a certain range. A pair of flat plates Since the voltage can change by 100 V or more even if the distance between the targets 10a and 10b changes by about 1 cm, from the viewpoint of continuing stable sputtering, a pair of flat plates from the start to the end of sputtering. The change in the average interval between the targets 10a and 10b is preferably 5 mm or less, more preferably 4 mm or less, further preferably 3 mm or less, still more preferably 2 mm or less, and 1 mm or less. Is even more preferable.

As shown in FIG. 2-2, the interval adjusting mechanism 19 can be installed in the sputtering chamber 11, but when installed in the sputtering chamber 11, the interval adjusting mechanism 19 must be made vacuum resistant, and the interval adjusting mechanism 19 must be made vacuum resistant. Since there is a possibility that the inside of the sputtering chamber 11 may be exposed to plasma or particles may accumulate to cause a malfunction, it is necessary to take preventive measures. Further, when oil such as lubricating oil is used for the interval adjusting mechanism 19, it may evaporate in a vacuum atmosphere, and it is necessary to deal with it. Therefore, as shown in FIG. 2-3, it is preferable to install at least a part of the interval adjusting mechanism 19 outside the sputtering chamber 11 (in FIG. 2-3, like the screw shaft in the case of the ball screw linear motion mechanism). The linear motion component is installed inside the chamber 11, but the power source such as the motor is installed outside the chamber 11), and as shown in FIG. 2-1 the entire interval adjusting mechanism 19 is located outside the sputtering chamber 11. It is more preferable to install it. When the interval adjusting mechanism 19 is installed outside the sputtering chamber 11, a part of the inside of the sputtering chamber 11 is an expansion / contraction member having an air blocking performance arranged so as to be expandable and contractable according to the operation of the interval adjustment mechanism 19. It is preferable that the boundary with the outside is defined by 52. By expanding and contracting the telescopic member 52 in accordance with the operation of the spacing adjusting mechanism 19, even if the movable part of the spacing adjusting mechanism 19 moves during sputtering, the inside of the sputtering chamber 11 is shielded from the atmosphere to create a vacuum (= less than atmospheric pressure). Can be maintained. The telescopic member 52 is not particularly limited as long as it has the above-mentioned function, and examples thereof include a bellows. As the material of the elastic member, it is preferable to use stainless steel, titanium, high nickel alloy (Hastelloy), aluminum, etc. from the viewpoint of durability in repeated expansion and contraction in a state where a force corresponding to atmospheric pressure is applied inside and outside. ..

In order to efficiently deposit the sputtered particles 13 on the member 16 on which the sputtered particles 13 are deposited, the direction of the forced gas flow of the sputtered gas 17 must be perpendicular to the surface of the member 16 on which the sputtered particles 13 are deposited. preferable.

It is desirable that the member 16 (typically the substrate to be filmed) on which the sputtered particles 13 are deposited is cooled in order to prevent the sputtered particles adhering to the member 16 from growing. When cooling, the material of the member 16 on which the sputtered particles 13 are deposited is not particularly limited, and plastic, glass, metal, ceramics, or the like can be used. When not cooled, heat-resistant materials such as glass, metal, and ceramics are preferable as the material of the member 16 on which the sputtered particles 13 are deposited. This is because the gas flow sputtering has an effect of flowing gas toward the member 16 side, and the plasma may reach the vicinity of the member 16. Among these, the member 16 has aluminum oxide, silicon oxide, zirconium oxide, magnesium oxide, yttrium oxide, calcium oxide, titanium oxide, boron nitride, aluminum, iron, copper, and titanium in order to facilitate recovery of the attached sputtered particles. , Niobium, tantalum, tungsten, molybdenum, cobalt, chromium, nickel, and graphite, preferably composed of one or more materials selected from the group, particularly without reacting with sputtered particles. Those with poor wettability are more preferable. In addition, it is preferable to select the material in consideration of contamination depending on the final application. Further, as the member 16, a method of directly depositing on the same material as the sputtered particles 13 is also possible. In this case, a method of depositing sputtered particles on the eroded portion of the used sputtering target and returning it to its original shape to regenerate the sputtering target is also conceivable. The sputtering target thus regenerated may be pressurized and / or heated as needed.

The shape of the member 16 on which the sputtered particles 13 are deposited is not particularly limited, but can generally be in the form of a plate or a film. The member 16 on which the sputtered particles 13 are deposited can be supported by the holder 18 in the gas flow sputtering apparatus by a method such as clamping, screwing, adhesive, or adhesive tape. It is also possible to make the member 16 into a box-shaped container shape in order to recover more sputtered particles.

As the sputter gas 17, rare gases such as He, Ar, Ne, Kr, and Xe, and inert gases such as N ₂ and O ₂ can be used alone or in combination of two or more. Among these, Ar is preferable in consideration of cost, and Kr and Xe are preferable from the viewpoint of efficiently moving sputtered particles. Further, in addition to the inert gas, N ₂ and / or O ₂ can be used if necessary. By using N ₂ and / or O ₂ , reactive sputtering of nitrides and oxides can be performed targeting metals, so non-equilibrium materials and composites that cannot be obtained by conventional manufacturing methods can be made into high-purity powders. The advantage that it can be obtained as a raw material is obtained.

In the gas flow sputtering apparatus, the flow rate of the sputtering gas can be significantly increased as compared with the DC magnetron sputtering apparatus. By increasing the flow rate of the sputter gas, it becomes possible to deposit the sputter particles on the member on which the sputter particles are deposited at high speed. In one embodiment of the gas flow sputtering apparatus according to the present invention, the flow rate of the sputtering gas ^{can be 1 sccm / cm 2} or more. The flow rate of the sputter gas ^{is preferably 2} sccm / cm 2 or more, and more preferably 5 sccm / cm ² or more. On the other hand, if the flow rate of the sputter gas is too large, the pressure in the chamber rises due to the limitation of the capacity of the exhaust pump. Therefore, ^{it is preferably 200 sccm / cm 2} or less, and 100 sccm / cm ² or less. More preferably, it is 50 sccm / cm ² or less, and even more preferably. ^{sccm refers to ccm (cm 3} / min) at 0 ° C. and 1 atm. Here, the flow rate is a value when the flow rate of the sputtering gas is divided by the total projected area of the opposing sputtering surfaces of the pair of flat plate targets 10a and 10b. For example, if the flow rate of the sputter gas is 5000 sccm and both opposing targets ^{have a sputter surface having a projected area of 10 cm in length × 10 cm in width = 100 cm 2} , the flow rate is 5000 sccm / (100 × 2) cm. ² = 25 sccm / cm ² .

Further, in the gas flow sputtering apparatus, the pressure of the sputtering gas can be significantly increased as compared with the DC magnetron sputtering apparatus. The advantage that the discharge voltage can be lowered by increasing the gas pressure can be obtained. In one embodiment of the gas flow sputtering apparatus according to the present invention, the absolute pressure of the sputtering gas can be 10 Pa or more. The absolute pressure of the sputtering gas is preferably 20 Pa or more, more preferably 30 Pa or more, and more preferably 40 Pa or more. On the other hand, if the absolute pressure of the sputtering gas is too high, abnormal discharge tends to increase, so it is preferably 200 Pa or less, more preferably 150 Pa or less, and even more preferably 100 Pa or less. Here, the absolute pressure of the sputtering gas refers to the pressure in the space between the pair of opposing targets, but since the pressure in the sputtering chamber 11 is generally high in uniformity, the space in the sputtering chamber 11 can be used. Substantially the same value can be obtained even if the measurement is performed at another location such as the vicinity of the sputter gas discharge port 14 or the vicinity of the exhaust port 20.

From the viewpoint of improving the productivity of the sputtering film by the gas flow sputtering apparatus, it is preferable that the power density is high. However, when the power density is increased, there arises a problem that abnormal discharge is likely to occur. In one embodiment of the gas flow sputtering apparatus according to the present invention, the occurrence of abnormal discharge is suppressed by providing an interval adjusting mechanism that keeps the interval between the pair of flat plate targets within a certain range. Even if the power density is increased, the apparatus can be stably operated by gas flow sputtering for a long time. Illustratively, the gas flow sputtering apparatus according to the present invention ^{can be operated at a power density of 10 W / cm 2} or more, preferably at a power density of 20 W / cm ² or more, and more preferably at a power density of 20 W / cm 2 or more. It can be operated at 30 W / cm ^{2 or more.} The upper limit of the power density is not set in particular, but if an excessively high power density is set, the discharge voltage rises. Therefore, it is common to adjust the power density so that the discharge voltage is 1000 V or less, and as much as possible. It is preferable to operate with a discharge voltage of 900 V or less in order to suppress the occurrence of abnormal discharge. Here, the power density refers to the total power divided by the total area of the sputtered surfaces of the opposing targets (here, the total projected area of the sputtered surfaces of the pair of flat plate targets facing each other). The total projected area of the sputtering surface of the target, a sputtering surface is 150cm ² × ² = 300cm ² is a flat plate target pair of vertical 10 cm × horizontal 15cm.

The target material is not particularly limited, but a conductive material such as a metal (including an alloy) can be preferably used. Further, an insulating material can be used, and a conductive material and an insulating material can be used in combination. Further, as the target material, a ferromagnetic material containing one or more metal elements selected from the group consisting of Co, Fe, Ni and Gd can be used. Non-magnetic materials such as non-magnetic metals (aluminum, copper, ruthenium, zinc, titanium, manganese, scandium, zirconium, hafnium, chromium alloys, etc.), oxides, carbides, nitrides, carbonitrides and carbon can also be used. It is possible to use a ferromagnetic material and a non-magnetic material together. As a sputtering target that can remarkably enjoy the effect of suppressing abnormal discharge by the gas flow sputtering apparatus according to the present invention, a sputtering target composed of a composite of a conductive material and an insulating material, and a composite of a non-magnetic material and a magnetic material. Sputtering targets composed of bodies can be mentioned. Since such a complex contains an insulating material or a non-magnetic material, abnormal discharge is particularly likely to occur during sputtering, so that there is a great merit in using the gas flow sputtering apparatus according to the present invention. Examples of combinations of materials constituting a composite of a ferromagnetic material and a non-magnetic material include a non-magnetic material-containing Cr-Co alloy-based magnetic material, a non-magnetic material-containing Cr-Pt-Co alloy-based magnetic material, and a non-magnetic material. Containing Pt-Co alloy-based magnetic material, non-magnetic material-containing Pt-Fe alloy-based magnetic material, non-magnetic material-containing Fe-Ni alloy-based magnetic material, non-magnetic material-containing Fe-Co alloy-based magnetic material, non-magnetic material-containing Fe -Ni-Co alloy-based magnetic materials and the like can be mentioned. A sputtering target composed of a composite of a non-magnetic material and a magnetic material is provided as a non-magnetic material particle dispersion type sputtering target in which non-magnetic material particles are dispersed in a ferromagnetic material in a typical embodiment.

The gas flow sputtering apparatus according to the present invention can be aimed at producing a sputtering target raw material, rather than forming a high-quality sputtering film. In this case, it is preferable that the sputtering target used in the gas flow sputtering apparatus according to the present invention can be produced at low cost. For example, a sputtering target having a high relative density is often used to form a homogeneous sputtering film, but such a high relative density is required for the sputtering target used in the gas flow sputtering apparatus according to the present invention. Not done. Therefore, in one embodiment, the gas flow sputtering target according to the present invention can have a relative density of 90% or less, 80% or less, or 70% or less. However, if the relative density is too low, it becomes difficult to secure sufficient strength for use as a sputtering target. In addition, the resistance value of the target itself increases, and in some cases, conductivity cannot be obtained. Therefore, the relative density of the gas flow sputtering target according to the present invention is preferably 40% or more, more preferably 50% or more, and even more preferably 60% or more. Since such a target having a low relative density can be produced by simply sintering the raw material powder at a low temperature or hardening it only by cold forming, it can be produced at a low cost. It can also be applied to materials for which it has been difficult to shape the target, such as difficult-to-sinter materials, low-melting-point materials, materials with a large melting point difference, and materials that require high purification. The relative density is a value obtained by dividing the measured density by the theoretical density and showing it as a percentage. The measured density is calculated from the volume obtained from the weight and the dimensional shape. The theoretical density is theoretically determined according to the material composition constituting the sputtering target.

From the viewpoint of improving the productivity of the sputtering film by the gas flow sputtering apparatus, the total projected area of the opposing sputtering surfaces of the pair of flat plate targets ^{is preferably 300 cm 2} or more, more preferably 500 cm ² or more, and 1000 cm. More preferably, it is ^{2 or more.} Although no particular upper limit for the total projected area, considering the practicality, it is generally not more 10000 cm ² or less, it is typical at 8000 cm ² or less, more not more 6000 cm ² or less Typical. The total projected area of the sputtered surfaces of the pair of flat plate targets facing each other is calculated as ^{, for example, 10 cm × 20 cm × 2 = 400 cm 2} when the sputtered surface of each flat plate target has a rectangular shape of 10 cm × 20 cm.

The shape of the sputtered surfaces of the flat plate targets facing each other is not particularly limited, and examples thereof include a square, a rectangle, a polygon, an ellipse, and a circle. Of these, a rectangle is preferable in order to efficiently recover the sputtered particles. Further, the facing surface of the flat plate target has a length in a direction perpendicular to the direction in which the sputter gas flows (Y in FIG. 1) rather than a length in a direction parallel to the direction in which the sputter gas flows (X in FIG. 1). ) Is longer, because the sputtering efficiency can be increased, which is preferable. Specifically, Y / X ≧ 1 is preferable, Y / X ≧ 1.2 is more preferable, and Y / X ≧ 1.5 is even more preferable. However, if Y / X is too large, it becomes difficult to handle the target. Therefore, Y / X ≦ 20 is preferable, Y / X ≦ 15 is more preferable, and Y / X ≦ 10 is preferable. Even more preferable.

The thickness of each of the pair of flat plate targets is not particularly limited and may be appropriately set according to the film formation usage time and the like, but a thicker one is preferable from the viewpoint of increasing the continuous sputtering time. Therefore, the thickness of each flat plate target is preferably 3 mm or more, more preferably 5 mm or more, and even more preferably 10 mm or more. However, since there is a technical limit to increasing the thickness, it is generally 30 mm or less, 20 mm or less is typical, and 15 mm or less is more typical. In order to carry out continuous sputtering for a long time, a plurality of flat plate targets may be laminated and used. By adopting such a configuration, it is not necessary to replace the sputtering target every time one sheet is consumed.

The flat plate targets 10a and 10b can be fixed to the backing plate 47 as needed and then attached to the cooling device 50 in the gas flow sputtering apparatus. In the present invention, when the backing plate 47 is used, the assembly of the flat plate target and the backing plate is called a "flat plate target", and the "flat plate target" as the assembly is fixed to the cooling device 50 in the gas flow sputtering apparatus. I decided to. Examples of the backing plate material include copper, copper alloy, aluminum, aluminum alloy, titanium, titanium alloy, iron, iron alloy, molybdenum, molybdenum alloy, cobalt, and cobalt alloy.

When the backing plate is not used, the flat plate targets 10a and 10b can be fixed to the cooling device 50 by using the fixing member 45 described later. When the backing plate is not used, the bottoms of the flat plate targets 10a and 10b can be formed into a backing plate shape. In other words, the flat plate targets 10a and 10b and the backing plate can be integrated with the same material.

The method of fixing the flat plate targets 10a and 10b to the backing plate 47 is not particularly limited, and examples thereof include a method of bonding with an adhesive and a method of diffusion bonding with the backing plate 47. In the method of bonding with an adhesive, it is preferable to use a conductive adhesive having heat resistance because the bonded portion is exposed to a high temperature by setting the power density high as described above. Specifically, the heat-resistant conductive adhesive preferably has a melting point of 200 ° C. or higher.

The sputtering gas 17 flows into the sputtering chamber 11 from the sputtering gas discharge port 14, and flows in the space 12 between the pair of flat plate targets 10a and 10b in the direction of the arrow. The sputter gas discharge port 14 may be one or two or more. However, over the length of the side surface of the pair of flat plate targets 10a and 10b on the side where the sputter gas 17 flows in (in other words, the length in the longitudinal direction of the slit serving as the inlet of the space portion 12) (Y in FIG. 1). Two or more sputter gas discharge ports 14 may be installed along the longitudinal direction of the slit in order to reduce the deviation of the flow rate of the inflowing sputter gas 17 or to enable the flow rate adjustment of the sputter gas 17. preferable. When two or more sputter gas discharge ports 14 are installed, in order to simplify the piping structure, the sputter gas supplied from one or two or more gas supply pipes is branched, and the number is larger than that of the gas supply pipes. A sputter gas discharge unit 22 that allows the gas to flow out from the discharge port of the above can be used. One or two or more sputter gas discharge units 22 can be installed.

A structural example of such a gas discharge unit 22 is shown in FIG. The gas discharge unit 22 is connected to a gas introduction pipe 28 having an inlet 24 for introducing the sputter gas 17 from a gas supply pipe (not shown) and a gas introduction pipe 28, and a large number of sputter gas discharge ports 14 Includes tubular members 26 arranged in a row on the side surface. The sputter gas 17 that has flowed in from the inlet 24 of the gas discharge unit 22 passes through the inside of the gas introduction pipe 28 and the tubular member 26 in order, and then flows out from a large number of sputter gas discharge ports 14. The sputter gas discharge ports 14 are preferably arranged along the longitudinal direction of the slits that serve as the inlets of the space portions 12.

Even if the flow rate of the spatter gas 17 flowing out from each spatter gas discharge port 14 is controlled by a flow rate adjusting mechanism such as a mass flow controller and a flow rate control valve (butterfly valve, needle valve, gate valve, glove valve, ball valve) for each discharge port. Alternatively, such a flow rate adjusting mechanism may be installed according to the number of gas supply pipes connected to the gas discharge unit 22, and the flow rate of the sputter gas 17 flowing out from the plurality of discharge ports 14 may be controlled collectively.

The relative positional relationship between the sputter gas discharge port 14 and the pair of flat plate targets 10a and 10b may be fixed, but may be provided with a position adjusting mechanism for making the relative adjustment as necessary. .. As a position adjusting mechanism, for example, the gas introduction pipe 28 is fixed to the wall of the sputtering chamber 11 by using a sealing material 29 such as a ferrule, an O-ring, a packing, and a gasket, and the sealing material 29 is loosened to loosen the sealing material 29 of the gas introduction pipe 28. A mechanism for adjusting the position from the wall can be mentioned (see FIGS. 2-1 to 2-3). In this case, it is preferable to provide the sealing material 29 on the outside of the sputtering chamber 11 from the viewpoint of workability.

FIG. 3 shows a schematic view showing an example of a cross-sectional structure around the gas flow sputtering flat plate targets 10a and 10b and the fixing member 45 according to the present invention when the backing plate 47 is not used. The target has a mounting portion 102 extending from the side surface 101, and the mounting portion 102 is sandwiched between the conductive fixing member 45 and the cooling device 50 via the diaphragm (indirect cooling plate) 46. The target is fixed to the cooling device 50. It is also possible to fix the target to the cooling device 50 in a positional relationship in which the mounting portion 102 is directly sandwiched between the conductive fixing member 45 and the cooling device 50 without interposing the diaphragm 46. The cooling efficiency is higher when the diaphragm 46 does not exist, but in this case, it is necessary to remove the cooling water 48 in order to prevent the cooling water 48 from leaking from the cooling device 50 when the inside of the sputtering chamber 11 is evacuated. Therefore, it is preferable to install the diaphragm 46 from the viewpoint of maintainability.

The reason why the conductive fixing member 45 is used is that it is difficult to obtain sufficient strength of the insulating material. The mounting portion 102 can be formed by integrally molding with the flat plate target main body portion. The area where the mounting portion 102 is installed is not particularly limited as long as the flat plate targets 10a and 10b can be fixed to the cooling device 50, but the mounting portion 102 continuously surrounds the side surfaces 101 of the flat plate targets 10a and 10b. It may be provided, or may be provided intermittently at a plurality of locations as many as necessary for fixing the flat plate targets 10a and 10b to the cooling device 50. From the viewpoint of workability of the flat plate targets 10a and 10b and the strength of the mounting portion, it is preferable that the mounting portion 102 is continuously provided so as to surround the side surfaces 101 of the flat plate targets 10a and 10b.

In order to perform stable discharge, it is preferable that the conductive fixing member 45 sandwiching the mounting portion 102 does not protrude upward from the upper surface (sputtering surface) 103 of the flat plate targets 10a and 10b. Therefore, it is preferable that the upper surface of the mounting portion 102 extending from the side surface 101 is lower than the upper surface 103 of the flat plate targets 10a and 10b. In this case, when the cross section of the target is observed, a step is generated on the upper surface 103 of the flat plate targets 10a and 10b and the upper surface of the mounting portion 102. On the other hand, from the viewpoint of ensuring the fixing strength between the flat plate targets 10a and 10b and the cooling device 50, the lower surface 104 of the mounting portion 102 extending from the side surface 101 is at the same height as the lower surface 106 of the flat plate targets 10a and 10b. Is preferable. That is, it is preferable that the lower surface 106 of the flat plate targets 10a and 10b and the lower surface 104 of the mounting portion 102 are on the same plane.

The material of the conductive fixing member 45 is not particularly limited, but it is preferably heat resistant. Examples of the conductive material having heat resistance include metals, in particular, a metal having a melting point higher than the melting point of aluminum (660.3 ° C.) is preferable, a metal having a melting point of 700 ° C. or higher is more preferable, and a metal having a melting point of 800 ° C. or higher is more preferable. A metal having a melting point is even more preferable, and a metal having a melting point of 1000 ° C. or higher is even more preferable. Carbon such as graphite can also be used. For example, a material selected from the group consisting of iron, copper, titanium, niobium, tantalum, tungsten, molybdenum, cobalt, chromium, nickel, and graphite may be used alone, or an alloy in which two or more kinds are combined (stainless steel is also used). Included) or metal-cobalt composites may be used. Among these, stainless steel is preferable because of its high strength, easy availability, and low cost.

The shape and dimensions of the conductive fixing member 45 are not particularly limited as long as the flat plate targets 10a and 10b can be fixed to the cooling device 50 in a positional relationship in which the mounting portion 102 is sandwiched between the conductive fixing member 45 and the cooling device 50. However, for the reason of stable discharge, the upper surface of the conductive fixing member 45 preferably does not protrude upward from the upper surface of the flat plate targets 10a and 10b, and is located lower than the upper surface of the flat plate targets 10a and 10b. Is more preferable. Further, the conductive fixing member 45 may be formed of an integrally molded product, or may be formed by combining two or more parts. For example, in the embodiment shown in FIG. 3, when the mounting portion 102 is continuously provided so as to surround the side surface 101 of the flat plate targets 10a and 10b, the conductive fixing member 45 is the same as the lower surface 104 of the mounting portion 102. Placed on a frame-shaped first fixing part 45a having a lower surface on a plane, an upper surface on the same plane as the upper surface of the mounting portion 102, and an inner side surface in close contact with the side surface of the mounting portion 102, and the first fixing part 45a. The second fixed component 45b to be mounted on the lower surface on the same plane as the upper surface of the mounting portion 102, the upper surface at a position lower than the upper surface 103 of the flat plate targets 10a and 10b, and the side surface 101 of the flat plate targets 10a and 10b. It can be composed of a frame-shaped second fixing part 45b having an inner surface in close contact with each other. In this case, the first fixing part 45a and the second fixing part 45b are in contact with each other so that the outer surfaces of the first fixing part 45a and the second fixing part 45b are continuous without a step, which simplifies the sputtering device and the shield shape. It is preferable because it can be used. In a typical embodiment, the first fixing part 45a and the second fixing part 45b can be provided as a rectangular frame, respectively.

It is desirable that the conductive fixing member 45 is not sputtered. If the conductive fixing member 45 is sputtered, the desired composition of the sputtered film cannot be obtained, and the maintenance frequency of the conductive fixing member 45 increases, which is inconvenient. Further, although it is ideal that the entire amount of sputtered particles is deposited on the member 16, if the sputter rate is increased in order to increase the production efficiency, a large amount of sputtered particles are scattered around the flat plate targets 10a and 10b. As a result, sputtered particles are likely to be deposited on the conductive fixing member 45 and further spread to the periphery. When the deposition range of the sputtered particles is widened, if the sputtered particles are conductive, the portion that should be the cathode potential may cause a short circuit with the portion of the anode (earth) potential. Therefore, it is desirable that the conductive fixing member 45 is covered with the insulating shield member 49. From a different point of view, it can be said that the insulating shield member 49 can function as a member for depositing sputtered particles.

In the embodiment shown in FIG. 3, the insulating shield member 49 has a side plate 492 that covers the outer surface of the conductive fixing member 45 and a top plate 493 that covers the upper surface of the conductive fixing member 45. Further, in order to enhance the effect of preventing the conductive fixing member 45 from being sputtered, the distance L3 between the lower surface of the upper surface plate 493 of the insulating shield member 49 and the upper surface of the conductive fixing member 45 shall be 10 mm or less. Is preferable, and it is more preferably 5 mm or less, and even more preferably 2 mm or less. Even if the lower surface of the upper surface plate 493 of the insulating shield member 49 and the upper surface of the conductive fixing member 45 are in contact with each other, it does not cause an abnormal discharge, so L3 may be 0.

It is desirable that the insulating shield member 49 is made of a heat resistant material. Further, as for the insulation resistance of the insulating shield member 49, the dielectric breakdown voltage at the thickness of the member to be installed is preferably 1 kV or more, more preferably 2 kV or more, and even more preferably 10 kV or more. A preferred example of the heat-resistant material constituting the insulating shield member 49 is one selected from the group consisting of aluminum oxide, silicon oxide, zirconium oxide, magnesium oxide, yttrium oxide, calcium oxide, titanium oxide, and boron nitride. Alternatively, two or more types can be mentioned. With these materials, it is easy to recover the adhered sputtered particles.

In order to prevent abnormal discharge, it is desirable that the insulating shield member 49 does not come into contact with the targets 10a and 10b. Therefore, if the distance between the insulating shield member 49 and the targets 10a and 10b is increased, the conductive fixing member 45 The portion not covered by the insulating shield member 49 becomes large, and the effect of preventing the conductive fixing member 45 from being sputtered becomes weak. Therefore, when the pair of flat plate targets 10a and 10b are viewed in a plan view, the closest contact distance (L1) between the targets 10a and 10b and the insulating shield member 49 is preferably adjusted to 0.1 mm or more. It is more preferable to adjust to 3 mm or more, and even more preferably to adjust to 0.5 mm or more. Further, the closest contact distance (L1) is preferably adjusted to 5 mm or less, more preferably 3 mm or less, and even more preferably 1 mm or less.

In the embodiment shown in FIG. 3, when the flat plate targets 10a and 10b are viewed in a plan view, a closest gap (L1) is formed between the targets 10a and 10b and the insulating shield member 49. In this case, there is a possibility that the sputter gas enters through the gap and the conductive fixing member 45 is sputtered. Therefore, in order to enhance the effect of preventing the conductive fixing member 45 from being sputtered, as shown in FIG. 4, an insulating shield is provided so as to cover the edge of the upper surface (sputtering surface) 103 of each of the flat plate targets 10a and 10b. It is also possible to arrange the member 49. Even in this case, it is preferable to adjust the closest contact distance (L1) between the targets 10a and 10b to the insulating shield member 49 within the range as described above.

If necessary, the insulating shield member 49 may be coated with yet another shield member so as to suppress the deposition of sputter particles on the insulating shield member 49. The shield member in this case is preferably heat resistant, but it does not matter whether it is conductive or insulating.

When the material of the shield member 49 is changed from insulating to conductive, the discharge voltage is also high as the discharge power is increased, so that an arc discharge occurs between the shield member 49 and the conductive fixing member 45. Since the risk is high, it is necessary to make the shield member 49 insulating in order to perform stable sputtering for a long period of time.

Since the cooling device 50 is in contact with the flat plate targets 10a and 10b, it can be a cathode potential. Therefore, in order to prevent the cooling device 50 from being sputtered, it is preferable to arrange the insulating shield member 501 for the cooling device so as to cover the outer surface of the cooling device 50. If the insulating shield member 501 covers at least a part of the outer surface of the cooling device 50, a sputter prevention effect can be obtained, but it is preferable that the entire outer surface is covered. The insulating shield member 501 can be directly attached to the outer surface of the cooling device 50. Suitable materials for the insulating shield member 501 for the cooling device are as described in the insulating shield member 49.

FIG. 7 shows a schematic view showing an example of a cross-sectional structure of the gas flow sputtering flat plate targets 10a and 10b according to the present invention when the backing plate 47 is used. The roles of the components represented by the same reference numerals and their preferred embodiments are as described in FIG. 3, and duplicate description will be omitted, and a configuration different from that of the embodiment of FIG. 3 will be mainly described. In the target, the portion of the backing plate 47 extends from the side surface 101 to form the mounting portion 102. The target is fixed to the cooling device 50 in a positional relationship in which the mounting portion 102 is directly sandwiched between the conductive fixing member 45 and the cooling device 50. In the present embodiment, since the backing plate 47 exists, there is no possibility that the cooling water leaks when the inside of the sputtering chamber 11 is evacuated, so that it is not necessary to interpose the diaphragm 46.

Also in this embodiment, the shape and dimensions of the conductive fixing member 45 are such that the targets 10a and 10b can be fixed to the cooling device 50 in a positional relationship in which the mounting portion 102 is sandwiched between the conductive fixing member 45 and the cooling device 50. There are no particular restrictions. In the embodiment shown in FIG. 7, the conductive fixing member 45 is an integrally molded product, and has a lower surface on the same plane as the upper surface of the mounting portion 102, an upper surface at a position lower than the upper surface 103 of the flat plate targets 10a and 10b, and an upper surface. , Has a frame structure having an inner side surface in close contact with the side surface 101 of the flat plate targets 10a and 10b. In a typical embodiment, the conductive fixing member 45 can be provided as a rectangular frame.

In the embodiment of FIGS. 3 and 7, the insulating shield member 49 has a peripheral wall 491 erected so as to surround the side surface 101 at intervals L1 along the side surface 101 of the flat plate targets 10a and 10b. .. Due to the presence of the peripheral wall 491, the side surfaces of the flat plate targets 10a and 10b are hidden, so that the discharge is easily stabilized. Further, it can be expected that the conductive fixing member 45 of the plasma is less likely to be sputtered.

The peripheral wall 491 is not essential, and as shown in FIG. 5, a mode in which the peripheral wall 491 is not provided is also possible. Further, as shown in FIG. 6, the upper surface plate 493 of the insulating shield member 49 can be thickened to increase the strength of the insulating shield member. Since the side surface of the target can be hidden by this aspect, the same effect as that of the peripheral wall 491 can be expected.

The configuration of the insulating shield member 49 is not limited to the embodiments shown in FIGS. 3 to 7, and other embodiments can also be adopted. For example, in the embodiment shown in FIG. 2-2, the side plate 492 does not exist in the insulating shield member 49. In the embodiment shown in FIG. 2-3, the fastener mounting base 502 covers the top plate 493 and the side plate 492 of the insulating shield member 49.

FIG. 8 shows a plan view showing an example of the arrangement relationship between the flat plate targets 10a and 10b and the insulating shield member 49 when the rectangular flat plate targets 10a and 10b are used. In the embodiment shown in FIG. 8, rectangular flat plate targets 10a and 10b are arranged so as to be surrounded by a peripheral wall 491 of a rectangular frame-shaped insulating shield member 49.

The distance L1 between the side surfaces 101 of the flat plate targets 10a and 10b and the peripheral wall 491 of the insulating shield member 49 is preferably 0.1 mm or more, more preferably 0.2 mm or more in order to maintain a stable discharge. , 0.3 mm or more is even more preferable. Further, the interval L1 is preferably 2 mm or less, more preferably 1.5 mm or less, and even more preferably 1 mm or less, for the reason of preventing the fixing member 45 from being sputtered.

As a method of fixing the flat plate targets 10a and 10b to the cooling device 50, one or more through holes are provided in the conductive fixing member 45 and, in the case of installation, the diaphragm 46, and further, the flat plate targets 10a and 10b are also attached to the cooling device 50. A method of providing holes and inserting fasteners 51 such as bolts and screws into the through holes and mounting holes in order to fix them (see FIGS. 3 to 6) can be mentioned. It is also possible to provide one or more through holes in the mounting portion 102 and insert the fastener 51 (see FIG. 7). Further, as a method of fixing the insulating shield member 49, a through hole is provided in the insulating shield member 49, and a mounting hole is also provided in the insulating shield member 501 for the cooling device, and the through hole and the mounting hole are sequentially provided with mounting holes. A method of inserting and fixing a fastener 503 such as a bolt or a screw can be mentioned. In this case, when the fastener 503 is made of metal, it is preferable that the fastener 503 is grounded to an anode potential in order to prevent the fastener 503 from being sputtered.

As the mounting hole for the fastener 503, a metal is preferable to an insulating material such as ceramics from the viewpoint of durability. Therefore, a metal fastener mounting base 502 may be installed on the outer surface of the insulating shield member 501 for the cooling device, and a mounting hole may be provided in the fastener mounting base 502. The fastener mounting base 502 can be placed directly on the outer surface of the insulating shield member 501 so as to surround the outer surface of the insulating shield member 501. When the fastener 503 is made of metal, it is preferable that the fastener 503 is grounded to an anode potential in order to prevent the fastener 503 from being sputtered. Further, in order to prevent the fastener mounting base 502 from being sputtered, it is preferable that the fastener mounting base 502 is grounded to an anode potential.

According to an embodiment of a gas flow sputtering apparatus according to the present invention, the sputtering rate 0.005g / h / cm ² or more, preferably 0.01g / h / cm ² or more, more preferably 0.02 g / h / With cm ² or more, for example 0.005 to 0.1 g / h / cm ² , continuous sputtering can be performed for 5 hours or more without abnormal discharge. However, the reference area of the sputtering rate refers to the total area of the sputtering surfaces of the opposing targets (here, the total projected area of the opposing sputtering surfaces of the pair of flat plate targets). Then, the sputtered film obtained by sputtering using the gas flow sputtering apparatus according to the present invention is separated from the member on which the sputtered particles are deposited and recovered, and then pulverized to be used as a raw material for a sputtering target. be able to. A sputtering target can be manufactured by sintering this raw material. In particular, the present invention is useful as a method for efficiently producing a non-magnetic material particle-dispersed sputtering target having a fine structure.

According to one embodiment of the method for producing a sputtering target raw material using the gas flow sputtering apparatus according to the present invention, the total mass of sputtered particles deposited on the insulating shield member 49 is deposited on the member 16 on which the sputtered particles are deposited. It can be larger than the mass of sputtered particles. For example, the ratio of the total mass of the sputtered particles deposited on the insulating shield member 49 to the mass of the sputtered particles deposited on the member 16 can be 2 or more, 3 or more, and 4 or more. You can also do it. Therefore, it is also important to recover the sputtered particles deposited on the insulating shield member 49 and use them as a raw material for a sputtering target in order to improve the production efficiency.

Examples of the present invention are shown below, but these examples are provided for a better understanding of the present invention and its advantages, and are not intended to limit the invention.

<1. Verification of the effect of adjusting the spacing between flat plate targets>
(Test Example 1)
Using the flat plate target facing type gas flow sputtering apparatus having the configuration shown in FIGS. 1 and 2-1 (however, the structure shown in FIG. 3 is adopted as the mounting structure of the sputtering target), sputtering is performed with the configuration shown in FIGS. 3 and 8. A target was attached and a sputter film was formed under the following conditions. A ball screw linear motion mechanism was adopted as the spacing adjustment mechanism for the pair of flat plate targets. The sputtering target was prepared by machining the ingot produced by the sintering method to a predetermined shape.
Further, as shown in FIG. 9, the sputter gas discharge units are arranged in a row over the entire length of the slit serving as the inlet of the space portion 12 with a large number of gas discharge ports. The number of discharge ports of the sputter gas discharge unit was set to 20.
The shape of the first fixing part was a rectangular frame, and the material of the first fixing part was stainless steel. The shape of the second fixing part was a rectangular frame, and the material of the second fixing part was stainless steel.

<Gas flow sputtering conditions>
・ Power supply: DC power supply ・ Power density: 44W / cm ²
・ Sputter gas pressure: 85Pa
-Sputter gas flow rate (sum of flow rates from each discharge port): Ar: 21.8 sccm / cm ²
-Target shape: Rectangular flat plate-Target dimensions: 85 mm (X direction) x 135 mm (Y direction) x 20 mmt
・ Total projected area of target: 230 cm ²
・ Target material: Cu
-Target relative density: 99%
・ Spacing between a pair of flat plate targets before starting sputtering S ₁ : 30 mm
-Distance between the flat plate target and the substrate to be filmed D: 80 mm
-Material of the substrate to be filmed: Stainless steel-Dimensions of the substrate to be filmed: 200 mm x 200 mm x 3 mmt
-Substrate temperature to be filmed: 40 ° C
-Material of insulating shield member: Alumina (dielectric breakdown voltage: 50 kV)
・ Distance between flat plate target and insulating shield member L1: 0.5mm
-Distance between the lower surface of the upper surface plate of the insulating shield member and the upper surface of the conductive fixing member L3: 0.1 mm or less-Cooling the target: Use cooling water-Fixing parts and insulating shield member to the cooling device: Insulating shield member for bolt fastening / cooling device: Alumina (dielectric breakdown voltage: 50 kV)

In Test Example 1, the interval adjusting mechanism was not used, and sputtering was continued for the above sputtering time. As a result, in the initial stage of sputtering, continuous sputtering of 5 hours or more per batch was possible without abnormal discharge, but the average spacing S ₁ between a pair of flat plate targets exceeded 37 mm (total sputtering time of about 100 hours). Abnormal discharge increased from the vicinity, making it difficult to maintain stable sputtering. Based on the results of this test, the relationship between the discharge time and integrated power and the average reduction in target thickness was determined. The sputtering rate for this test was 0.062 g / h / cm ² . The ratio of the weight increase of the film-forming target substrate to the weight loss of the target after the sputtering test was 22%. The ratio of the increased weight of the insulating shield member to the reduced weight of the target after the sputtering test was 51%. Incidentally, the mean spacing S ₁ between the pair of flat plate target during the test was measured by calipers.

(Test Example 2)
Based on the relationship between the discharge time and integrated power obtained in Test Example 1 and the average decrease in target thickness, an interval adjustment mechanism is used so that the change width of the average interval between the pair of flat plate targets is 5 mm or less during sputtering. A sputter film was formed under the same conditions as in Test Example 1 except that the interval was adjusted manually. As a result, a total of 250 hours of sputtering time could elapse without generating abnormal discharge during the test. The sputtering rate for this test was 0.069 g / h / cm ² . The ratio of the weight increase of the film-forming target substrate to the weight loss of the target after the sputtering test was 26%. The ratio of the increased weight of the insulating shield member to the reduced weight of the target after the sputtering test was 46%.

(Test Example 3)
During sputtering, the chamber is opened periodically (every 10 hours) and the weight of the pair of flat plate targets is measured to calculate the change width of the average interval, and the change width is adjusted to 5 mm or less by the interval adjustment mechanism. A sputter film was formed under the same conditions as in Test Example 1 except that the interval was adjusted manually. As a result, a total of 250 hours of sputtering time could elapse without generating abnormal discharge during the test. The sputtering rate for this test was 0.067 g / h / cm ² . The ratio of the increased weight of the film-forming target substrate to the reduced weight of the target after the sputtering test was 25%. The ratio of the increased weight of the insulating shield member to the reduced weight of the target after the sputtering test was 48%.

<2. Verification of the effect of the insulating shield member>
(Test Example 4)
A sputtering film was formed under the same sputtering conditions as in Test Example 1 except that the insulating shield member was removed and a sputtering test was performed. In this case, an abnormal discharge occurred between the target fixing component and another member having an anode potential, and stable film formation could not be performed, so that film formation was stopped immediately after the start. When the inside of the sputtering chamber was checked, abnormal discharge marks remained on the surfaces of the target and the fixing member.

(Test Example 5)
A sputtering film was formed under the same sputtering conditions as in Test Example 1 except that the distance L1 between the flat plate target and the insulating shield member was set to 0 and the two were brought into contact with each other. In this case, abnormal discharge occurred frequently between the target and the insulating shield, and the film formation was stopped in 30 minutes. The sputtering rate for this test was 0.064 g / h / cm ² . The ratio of the weight increase of the film-forming target substrate to the weight loss of the target after the sputtering test was 31%. The ratio of the increased weight of the insulating shield member to the reduced weight of the target after the sputtering test was 44%.

(Test Example 6)
A sputtering film was formed under the same sputtering conditions as in Test Example 1 except that the distance L1 between the flat plate target and the insulating shield member was 2.2 mm. In this case, at the beginning of film formation, there were few abnormal discharges and stable film formation was possible, but after 3 hours, abnormal discharges occurred frequently and the discharge was stopped. When the inside of the sputtering chamber was checked, the fixing member was also sputtered. The sputtering rate for this test was 0.062 g / h / cm ² . The ratio of the increased weight of the film-forming target substrate to the reduced weight of the target after the sputtering test was 25%. The ratio of the increased weight of the insulating shield member to the reduced weight of the target after the sputtering test was 44%.

(Test Example 7)
A sputtering film was formed under the same sputtering conditions as in Test Example 1 except that the distance L1 between the flat plate target and the insulating shield member was 0.1 mm. In this case, there were few abnormal discharges at the beginning of film formation, and stable film formation was possible, but after 2 hours, abnormal discharges occurred frequently and the discharge was stopped. When the inside of the sputtering chamber was checked, an abnormal discharge mark remained between the target and the insulating shield. The sputtering rate for this test was 0.067 g / h / cm ² . The ratio of the increased weight of the film-forming target substrate to the reduced weight of the target after the sputtering test was 30%. The ratio of the increased weight of the insulating shield member to the reduced weight of the target after the sputtering test was 51%.

(Test Example 8)
A sputtering film was formed under the same sputtering conditions as in Test Example 1 except that the distance L1 between the flat plate target and the insulating shield member was 1.5 mm. In this case, the abnormal discharge was small and the film formation was stable, and the film formation was completed as planned after 5 hours had passed. However, when the inside of the sputtering chamber was checked, the fixing member was also sputtered. The sputtering rate for this test was 0.069 g / h / cm ² . The ratio of the weight increase of the film-forming target substrate to the weight loss of the target after the sputtering test was 26%. The ratio of the increased weight of the insulating shield member to the reduced weight of the target after the sputtering test was 46%.

(Test Example 9)
A sputtering film was formed under the same sputtering conditions as in Test Example 1 except that the gas flow sputtering conditions were changed as follows.
・ Power density: 22 W / cm ²
・ Sputter gas pressure: 70Pa
-Sputter gas flow rate (sum of flow rates from each discharge port): Ar: 32.7 sccm / cm ²
-Target material: Cu-TiO _{2 -SiO 2}
-Target relative density: 95%
・ Distance between flat plate target and insulating shield member L1: 0.4mm
-Interval between a pair of flat plate targets before starting sputtering S ₁ : 20 mm
In this case, the abnormal discharge was small and the film formation was stable, and the film formation was completed as planned after 5 hours had passed. When the inside of the sputtering chamber was checked, no abnormality was found. The sputtering rate for this test was 0.013 g / h / cm ² . The ratio of the weight increase of the film-forming target substrate to the weight loss of the target after the sputtering test was 28%. The ratio of the increased weight of the insulating shield member to the reduced weight of the target after the sputtering test was 48%.

The sputtered film of Test Example 9 was peeled off from the substrate and recovered. Then, this film was pulverized to obtain a fine powder. This was filled in a carbon mold and hot-pressed in a vacuum atmosphere under the conditions of a temperature of 1000 ° C., a holding time of 2 hours, and a pressing force of 30 MPa to obtain a sintered body. Next, hot isotropic pressure processing (HIP) was performed. The conditions for hot isotropic pressure processing are a temperature rise rate of 300 ° C./hour, a holding temperature of 1000 ° C., and a holding time of 2 hours. The inside was pressurized at 150 MPa. After the holding was completed, it was naturally cooled in the furnace as it was. The average diameter of the oxide particles in the sintered body was measured by microscopic observation and found to be 0.4 μm.

(Test Example 10)
A sputtering film was formed under the same sputtering conditions as in Test Example 1 except that the gas flow sputtering conditions were changed as follows.
<Gas flow sputtering conditions>
・ Power density: 28 W / cm ²
・ Sputter gas pressure: 25Pa
-Sputter gas flow rate (sum of flow rates from each discharge port): Ar: 14.2 sccm / cm ²
-Target material: Cu-TiO ₂
-Target relative density: 97%
-Target dimensions: 143 mm (X direction) x 493 mm (Y direction) x 30 mmt
・ Total projected area of target: 1410 cm ²
・ Distance between flat plate target and insulating shield member L1: 0.8mm
In this case, the abnormal discharge was small and the film formation was stable, and the film formation was completed as planned after 5 hours had passed. Moreover, when the inside of the sputtering chamber was checked, no abnormality was found. The sputtering rate for this test was 0.011 g / h / cm ² . The ratio of the weight increase of the film-forming target substrate to the weight loss of the target after the sputtering test was 40%. The ratio of the increased weight of the insulating shield member to the reduced weight of the target after the sputtering test was 42%.

(Test Example 11)
Using the flat plate target facing type gas flow sputtering apparatus having the configuration shown in FIGS. 1 and 2-1 (however, the structure shown in FIG. 4 is adopted as the attachment structure of the sputtering target), the sputtering target is attached with the configuration shown in FIG. A sputter film was formed under the following conditions. A sputtering film was formed under the same apparatus configuration and sputtering conditions as in Test Example 1 except that the gas flow sputtering conditions were changed as follows.
<Gas flow sputtering conditions>
・ Distance between flat plate target and insulating shield member L1: 4.5mm
-Distance between the lower surface of the upper surface plate of the insulating shield member and the upper surface of the conductive fixing member L3: 4.6 mm
In this case, the abnormal discharge was small and the film formation was stable, and the film formation was completed as planned after 5 hours had passed. However, when the inside of the sputtering chamber was checked, the fixing member was also sputtered. The sputtering rate for this test was 0.028 g / h / cm ² . The ratio of the increased weight of the film-forming target substrate to the reduced weight of the target after the sputtering test was 48%. The ratio of the increased weight of the insulating shield member to the reduced weight of the target after the sputtering test was 37%.

(Test Example 12)
Using the flat plate target facing type gas flow sputtering apparatus having the configuration shown in FIGS. 1 and 2-1 (however, the structure shown in FIG. 5 is adopted as the attachment structure of the sputtering target), the sputtering target is attached with the configuration shown in FIG. A sputter film was formed under the following conditions. A sputtering film was formed under the same apparatus configuration and sputtering conditions as in Test Example 1 except that the gas flow sputtering conditions were changed as follows.
<Gas flow sputtering conditions>
・ Distance between flat plate target and insulating shield member L1: 0.6mm
-Distance between the lower surface of the upper surface plate of the insulating shield member and the upper surface of the conductive fixing member L3: 0.1 mm
In this case, the abnormal discharge was small and the film formation was stable, and the film formation was completed as planned after 5 hours had passed. However, when the inside of the sputtering chamber was checked, the fixing member was also sputtered. The sputtering rate for this test was 0.034 g / h / cm ² . The ratio of the weight increase of the film-forming target substrate to the weight loss of the target after the sputtering test was 44%. The ratio of the increased weight of the insulating shield member to the reduced weight of the target after the sputtering test was 40%.

(Test Example 13)
Using the flat plate target facing type gas flow sputtering apparatus having the configuration shown in FIGS. 1 and 2-1 (however, the structure shown in FIG. 6 is adopted as the attachment structure of the sputtering target), the sputtering target is attached with the configuration shown in FIG. A sputter film was formed under the following conditions. A sputtering film was formed under the same apparatus configuration and sputtering conditions as in Test Example 1 except that the gas flow sputtering conditions were changed as follows.
<Gas flow sputtering conditions>
・ Distance between flat plate target and insulating shield member L1: 0.6mm
-Distance between the lower surface of the upper surface plate of the insulating shield member and the upper surface of the conductive fixing member L3: 0.5 mm
In this case, the abnormal discharge was small and the film formation was stable, and the film formation was completed as planned after 5 hours had passed. Moreover, when the inside of the sputtering chamber was checked, no abnormality was found. The sputtering rate for this test was 0.007 g / h / cm ² . The ratio of the weight increase of the film-forming target substrate to the weight loss of the target after the sputtering test was 27%. The ratio of the increased weight of the insulating shield member to the reduced weight of the target after the sputtering test was 48%.

(Test Example 14)
Using the flat plate target facing type gas flow sputtering apparatus having the configuration shown in FIGS. 1 and 2-1 (however, the structure shown in FIG. 7 is adopted as the attachment structure of the sputtering target), the sputtering target is attached with the configuration shown in FIG. A sputter film was formed under the following conditions. A sputtering film was formed under the same apparatus configuration and sputtering conditions as in Test Example 1 except that the gas flow sputtering conditions were changed as follows.
<Gas flow sputtering conditions>
・ Power density: 33 W / cm ²
・ Sputter gas pressure: 130 Pa
-Sputter gas flow rate (sum of flow rates from each discharge port): Ar: 33.3 sccm / cm ²
-Target dimensions: 100 mm (X direction) x 150 mm (Y direction) x 10 mmt
・ Total projected area of target: 300 cm ²
-Interval between a pair of flat plate targets before starting sputtering S ₁ : 20 mm
・ Distance between flat plate target and insulating shield member L1: 0.2mm
-Distance between the lower surface of the upper surface plate of the insulating shield member and the upper surface of the conductive fixing member L3: 0.2 mm
-Backing plate material: Cu (structure integrated with the target)
In this case, the abnormal discharge was small and the film formation was stable, and the film formation was completed as planned after 5 hours had passed. Moreover, when the inside of the sputtering chamber was checked, no abnormality was found. The sputtering rate for this test was 0.033 g / h / cm ² . The ratio of the weight increase of the film-forming target substrate to the weight loss of the target after the sputtering test was 24%. The ratio of the increased weight of the insulating shield member to the reduced weight of the target after the sputtering test was 48%.

10a, 10b Flat plate target 11 Sputtering chamber 12 Space 13 Sputtered particles 14 Sputtered gas discharge port 15 DC power supply 16 Member for depositing sputtered particles 17 Sputtered gas 18 Holder (holding member)
19 Interval adjustment mechanism 20 Exhaust port 22 Gas discharge unit 24 Gas discharge unit inlet 26 Tubular member 28 Gas introduction pipe 29 Sealing material 45 Conductive fixing member 45a First fixing part 45b Second fixing part 46 Diaphragm 47 Backing plate 48 Cooling water 49 Insulating shield member 491 Peripheral wall 492 Side plate 493 Top plate 50 Cooling device 51 Fastener 52 Telescopic member 101 Target side surface 102 Mounting site 103 Flat plate target top surface (sputter surface)
104 Bottom surface of mounting site 106 Bottom surface of flat plate target 501 Insulating shield member for cooling device 502 Fastener Mounting base 503 Fastener

Claims (19)

A sputtering chamber that can evacuate the inside and
A pair of flat plate targets arranged so that the sputtering surfaces face each other at intervals in the sputtering chamber.
One or more gas outlets for supplying sputter gas between the pair of flat plate targets, and
An exhaust port for exhausting spatter gas and
A member that deposits sputter particles arranged so as to face the gas discharge port on the opposite side of the space between the pair of flat plate targets and the gas discharge port.
An interval adjustment mechanism that enables the interval adjustment of the pair of flat plate targets,
Equipped with a,
The interval adjusting mechanism is configured such that the change width of the average interval of the pair of flat plate targets during the sputtering process is 5 mm or less.
Gas flow sputtering equipment. The gas flow sputtering apparatus according to claim 1, further comprising a position adjusting mechanism capable of relatively adjusting the positions of the one or more gas discharge ports and the pair of flat plate targets. The gas flow sputtering apparatus according to claim 1 or 2, further comprising a flow rate adjusting mechanism for adjusting the flow rate of the sputtered gas supplied from the one or more gas discharge ports. The gas flow sputtering apparatus according to any one of claims 1 to 3, further comprising two or more gas discharge ports. The gas flow sputtering apparatus according to any one of claims 1 to 4, further comprising one or more gas discharge units in which two or more gas discharge ports are arranged. The gas flow sputtering apparatus according to any one of claims 1 to 5, wherein the interval adjusting mechanism is installed outside the sputtering chamber. The sixth aspect of the invention, wherein a part of the inside of the sputtering chamber is defined with a stretchable member having an air blocking performance, which is arranged so as to be expandable and contractible in accordance with the operation of the spacing adjusting mechanism. Gas flow sputtering equipment. The gas flow sputtering apparatus according to any one of claims 1 to 7, wherein the interval adjusting mechanism has a manually operated drive mechanism connected to at least one of the pair of flat plate targets. The gas flow sputtering apparatus according to any one of claims 1 to 8, wherein the interval adjusting mechanism has a motor drive mechanism connected to at least one of the pair of flat plate targets. The gas flow sputtering apparatus according to any one of claims 1 to 9, wherein the interval adjusting mechanism is configured so that the interval between the pair of flat plate targets can be adjusted at least based on the discharge time and the integrated power. Gas flow sputtering apparatus according to any one of claims 1 to 1 0 interval between the pair of flat plate target before the start of sputtering is 10 to 100 mm. The gas flow sputtering apparatus according to any one of claims 1 to 11, wherein the total projected area of the facing surfaces of the pair of flat plate targets is 300 cm ^{2 or more.} The gas flow sputtering apparatus according to any one of claims 1 to 12 , which can discharge under the condition that the power density is 10 W / cm ^{2 or more.} It said pair of plate target gas flow sputtering apparatus according to any one of claims 1 to 1 3, which is a composite of non-magnetic material and a magnetic material. A step of sputtering using a gas flow sputtering apparatus according to any one of claims 1 to 1 4, the change in the average distance between the pair of flat plate target from the sputtering start to the completion of sputtering is 5mm or less A method for producing a sputtering target raw material, which comprises operating an interval adjusting mechanism so as to. The manufacturing method according to claim 15 , wherein the sputtering is performed at a power density of 10 W / cm ^{2 or more.} The manufacturing method according to claim 15 or 16 , wherein the flow rate of the sputter gas is represented by the flow rate per ^{1 cm 2} of the total projected area of the facing sputter surfaces of the pair of flat plate targets, and sputtering is performed at 1 ^{sccm / cm 2 or more.} The production method according to any one of claims 15 to 17 , wherein the sputter gas is sputtered at a pressure of 10 Pa or more. The production method according to any one of claims 15 to 18 , wherein the member for depositing the sputtered particles is a used sputtering target, and the sputtered particles are deposited on the eroded portion of the target.

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