JP2007051337A - Sputtering electrode and sputtering apparatus provided with the sputtering electrode - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve a problem that when a film is formed by sputtering a target assembly made by jointing a target with a backing plate through a bonding material, the film formed by a target assembly that has caused warping in a jointing step acquires nonuniform thickness within the surface of a treated substrate. <P>SOLUTION: This sputtering electrode is produced by the steps of: preparing the target assembly by jointing the target 41 with the backing plate 42 through the bonding material; attaching the target assembly to a main body 4 of the sputter electrode through a portion 42a which is located at a part of the backing plate extending outer than the target; and connecting the target assembly with a warping-correcting means 7 for applying any one of a tensile force or a pressing force to a central region of the target assembly along a direction perpendicular to the surface to be sputtered of the target. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a sputtering electrode used for forming a film on a processing substrate by a sputtering method and a sputtering apparatus provided with the sputtering electrode.

  In the sputtering method, ions in plasma are accelerated and bombarded toward a target formed in a predetermined shape according to the composition of the film to be formed on the surface of the processing substrate, and target atoms are scattered to the surface of the processing substrate. A thin film is formed. In this case, since the target is subjected to ion bombardment and becomes high temperature, the target may be melted or cracked.

  Therefore, the target is joined to a backing plate made of, for example, copper via a bonding material made of a material having high thermal conductivity such as indium or tin to form a target assembly, and in this state, the sputter electrode body which is a sputter cathode The target is indirectly removed by cooling the backing plate with cooling water (refrigerant) during sputtering (Patent Document 1).

In general, the target and the backing plate are joined, for example, by placing the target and the backing plate formed in a predetermined shape on a heating plate, respectively, and heating each of the target and the backing plate to a predetermined temperature at which the bonding material is dissolved. After the bonding material is applied to the bonding surfaces, they are bonded together and naturally cooled to a temperature at which the bonding material solidifies in this state.
JP-A-7-26375 (see, for example, FIG. 1).

  When the target and the backing plate are joined as described above, the target assembly joined via the bonding material due to the difference in thermal expansion during heating based on the difference in material and area between the target and the backing plate. There is a problem that warpage occurs. In this case, the direction of warpage varies depending on the composition of the target that is the film forming material. When the warped target assembly is attached to the sputter electrode body and deposited by sputtering, the distance to the magnet assembly provided behind the target assembly differs between the central area of the target and the peripheral area. The film thickness becomes non-uniform within the substrate surface.

  This becomes more conspicuous when the area of the target is increased in order to form a thin film by sputtering on a substrate having a large area, such as a glass substrate for FPD production in recent years.

  Therefore, in view of the above points, an object of the present invention is to provide a sputter electrode that can be formed with a substantially uniform film thickness over the entire surface of the processing substrate without being affected by the warp of the target assembly during bonding. An object of the present invention is to provide a sputtering apparatus provided with a sputtering electrode.

  In order to solve the above problems, a sputtering electrode according to claim 1 includes a target assembly including a sputtering target and a backing plate bonded to the back side of the sputtering surface of the target via a bonding material. The target assembly is a sputter electrode that can be attached to the sputter electrode main body through a portion that extends outward from the target of the backing plate, and the attachment position of the backing plate to the sputter power source main body is located respectively. A warp correction means for applying either a tensile force or a pressing force is provided in the central region of the target assembly along a direction orthogonal to the horizontal plane.

  According to this, for example, the target assembly is fixed to the sputter electrode body via a portion extending outward from the target of the backing plate by fastening means such as bolts. Next, the warp correction means is connected to the center area on the back side of the backing plate, and the warp correction means applies a tensile force or a push to the center area of the target assembly according to the warp direction of the target assembly when bonded via a bonding material. Apply either pressure. As a result, the distance from the target sputtering surface to the processing substrate can be made substantially constant over the entire surface of the target, that is, the target sputtering surface when not in use can be made substantially horizontal, so that it is not affected by the warping of the target. Film formation with a uniform film thickness becomes possible.

  In this case, the warp correction means includes, for example, a support portion that is located behind the target assembly and is provided in the sputter power source main body, and a shaft portion that is screwed at one end to the support portion. If the other end is detachably attached to the central region of the backing plate, the warp can be corrected with a simple structure by applying a tensile force or a pressing force to the central region of the target assembly.

  If a plurality of the warp correction means are provided, the number of places where either a tensile force or a pressing force can be applied increases, and fine adjustment to make the sputtering surface of the target substantially horizontal becomes possible. This is particularly effective when the target is strained or has a large area.

  According to a fourth aspect of the present invention, there is provided a sputtering apparatus in which the sputter electrodes according to any one of the first to third aspects are juxtaposed at a predetermined interval to form a magnetic flux in front of each target. A magnet assembly that is provided at the rear of the assembly and includes a plurality of magnets, and an AC power source that alternately applies a negative potential, a ground potential, or a positive potential to each target. Features.

  According to this, when a negative potential is applied to one target via an AC power source and a ground potential or a positive potential is applied to the other target, the other target acts as an anode and one AC power source Plasma is generated between the targets connected to each other, and a target to which a negative potential is applied is sputtered. When the potential of the target is switched in accordance with the frequency of the AC power source, the other target is sputtered, and each target can be sputtered sequentially.

  Thereby, in combination with the fact that it is not affected by the warp at the time of joining the target and the backing plate and that the interval between the targets where the sputtered particles are not released can be set small, for a processing substrate having a large area, Even when a film is formed by sputtering, the film can be formed with a substantially uniform film thickness.

  If drive means for integrally driving each magnet assembly is provided so that the magnetic flux can move in parallel with respect to the target, an erosion region can be obtained over the entire surface of the target during sputtering, and the use of the target. It may be possible to increase efficiency.

  In this case, the magnet assembly has a support plate for supporting each magnet, and the support plate is provided with a long hole along the moving direction of each magnet assembly that allows the shaft portion of the warp correction means to be inserted. It should be provided.

  As described above, in the sputtering electrode of the present invention and the sputtering apparatus equipped with the sputtering electrode, the film thickness is substantially uniform over the entire surface of the processing substrate without being affected by the warp generated in the target assembly during bonding. There is an effect that a film can be formed.

  Referring to FIGS. 1 to 3, reference numeral 1 denotes a magnetron type sputtering apparatus (hereinafter referred to as “sputtering apparatus”) equipped with the sputtering electrode of the present invention. The sputtering apparatus 1 is of an in-line type and has a sputtering chamber 11 that can be maintained at a predetermined degree of vacuum through vacuum exhaust means (not shown) such as a rotary pump or a turbo molecular pump. A substrate transfer means 2 is provided in the upper space of the sputtering chamber 11. The substrate transport unit 2 has a known structure, for example, has a carrier 21 on which the process substrate S is mounted, and sequentially drives the processing substrate S to a position facing a target described later by intermittently driving the drive unit. it can.

  A gas introducing means 3 is provided in the sputtering chamber 11. The gas introduction means 3 communicates with a gas source 33 via a gas pipe 32 provided with a mass flow controller 31, and a sputtering gas such as argon or a reactive gas used in reactive sputtering is constant in the sputtering chamber 11. It can be introduced at a flow rate of. As the reaction gas, oxygen, nitrogen, carbon, hydrogen, ozone, water, hydrogen peroxide, or a mixed gas thereof is used.

  A sputtering electrode body 4 is provided below the sputtering chamber 11 so as to face the processing substrate S transferred to the film forming chamber 11. The sputter electrode body 4 has a substantially rectangular parallelepiped (rectangular in top view) target 41 disposed to face the processing substrate S. The target 41 is manufactured by a known method according to the composition of a thin film to be formed on the processing substrate S, such as Al, Ti, Mo, or ITO. The target 41 is bonded to a backing plate 42 having a known structure that cools the target 41 during sputtering through a bonding material such as indium or tin.

  In this case, for joining the target 41 and the backing plate 42, for example, the target 41 and the backing plate 42 formed in a predetermined shape are placed on a heating plate and heated to a predetermined temperature at which the bonding material dissolves, respectively. After the bonding material is applied to each bonding surface of 41 and the backing plate 42, they are bonded together and naturally cooled to a temperature at which the bonding material hardens in this state.

  After the target 41 and the backing plate 42 are joined to form a target assembly, the target assembly is attached to the frame 44 of the sputter electrode body 4 via the insulating plate 43. In this case, the portion 42a of the backing plate 42 that extends outward from the target 41 is provided with a plurality of openings (not shown) at a predetermined interval, and through the openings, a predetermined interval is formed on the upper surface of the frame 44. The target assemblies 41 and 42 are fixed by screwing the bolts B into the screw holes formed by placing.

  An earth shield (not shown) is installed around the target 41 so as to surround the target 41 in order to stably generate plasma. In this case, only the target 41 and the earth seal are positioned in the sputtering chamber 11 by vacuum sealing means such as an O-ring (not shown).

  The sputter electrode body 4 is equipped with a magnet assembly 5 positioned behind the target 41. The magnet assembly 5 has a support plate 51 provided in parallel to the target 41. The support plate 51 is made of a magnetic material that is smaller than the lateral width of the target 41 and is formed of a rectangular flat plate formed so as to extend on both sides of the target 41 along the longitudinal direction thereof. is there. On the support plate 51, rod-shaped central magnets 52 along the longitudinal direction of the target 41 and peripheral magnets 53 provided along the outer periphery of the support plate 51 are alternately provided with different polarities. In this case, the volume when converted to the same magnetization of the central magnet 52 is equal to the sum of the volumes when converted to the same magnetization of the peripheral magnet 53 (peripheral magnet: center magnet: peripheral magnet = 1: 2: 1). Designed to be

  As a result, a balanced closed-loop tunnel-shaped magnetic flux M is formed in front of each target 41, and the electrons ionized in front of the target 41 and the secondary electrons generated by sputtering are captured in front of the target 41. The plasma density can be increased by increasing the electron density.

  Then, the substrate transport unit 2 transports the processing substrate S to a position facing the target 41 and introduces a predetermined sputtering gas via the gas introduction unit 3. When a negative DC voltage or a high-frequency voltage is applied to the target 41 via the sputtering power source 6 connected to the target 41, an electric field perpendicular to the processing substrate S and the target 41 is formed, and plasma is generated in front of the target 41. Then, the target 41 is sputtered to form a film on the processing substrate S.

  By the way, when the target 41 and the backing plate 42 are joined as described above, due to the difference in thermal expansion during heating based on the difference in material and area between the target 41 and the backing plate 42, the bonding material is interposed. In some cases, the warped target assemblies 41 and 42 may be warped. In this case, when the target 41 is made of a material having a low melting point such as Al, warping occurs so that the central region R is raised, and on the other hand, when the target 41 is made of a material having a high melting point such as Ti or Cr, Warping occurs so that the area rises. If the target assemblies 41 and 42 in which warpage has occurred are mounted on the sputter electrode body 4 and a film is formed by sputtering, the film thickness may be non-uniform in the processing substrate S plane.

  In the present embodiment, the warp correction means 7 that applies either a tensile force or a pressing force to the central region of the target assemblies 41 and 42 along the direction orthogonal to the horizontal plane of the frame 44 to which the backing plate 42 is attached. It was decided to provide.

  As shown in FIGS. 2 and 3, the warp correction means 7 includes support parts 71 and 72 disposed behind the target assemblies 41 and 42 and a shaft part 73 supported by the support part 72. . The support plate 71 provided parallel to the back surface of the backing plate 42 is made of, for example, stainless steel, and is set to a thickness that does not deform even when a force is applied to correct warping.

  The support plate 71 is provided with four through holes 71a at positions facing the central region R of the backing plate 42 where the amount of warpage increases when warpage occurs. 72 is attached. The support piece 72 is made of, for example, stainless steel, and an opening 72a is formed at the center thereof. And the support piece 72 is being fixed to the support plate 71 with the volt | bolt B1 in the state which made the opening part 72a of the support piece 72 and the through-hole 71a formed in the support plate 71 correspond in the up-down direction. The support plate 71, the support piece 72, and a nut described later constitute a support portion.

  The shaft portion 73 is made of a stainless steel bar sized so as to be longer than the distance between the back surface of the backing plate 42 and the upper surface of the support plate 71, and thread grooves 73 a are formed at both ends thereof. ing. One end of the shaft portion 73 is disposed so as to protrude downward from the support piece 72, and a nut 74 is screwed into the protruded portion. The other end of the shaft 73 is fixed by being screwed into a screw hole formed on the back surface of the backing plate 42 so as to coincide with the opening 72a and the through hole 71a in the vertical direction.

  Here, since the power supply cable 6a from the sputtering power source 42 is connected to the backing plate 42 so as to apply a negative DC voltage or a high frequency voltage to the target 41, the backing plate 42 is used to insulate the warp correction means 7. 42. A concave portion is provided at a predetermined position on the back surface, and an insulating material 42b such as hard plastics having a thread groove provided therein is fitted in the concave portion, and the shaft 73 is surrounded by a hollow cylindrical hard plastics or the like. It is covered with an insulating material 73b.

  Further, since the magnet assembly 5 is located between the backing plate 42 and the support plate 71, the shaft portion 73 can be inserted into the support plate 51 of the magnet assembly as shown in FIG. An opening 51a is formed.

  Then, with the other end of the shaft portion 73 screwed into and fixed to the thread groove of the insulating material 42b, the shaft portion 73 is held on the support plate 71 side (downward in FIG. 2) while holding the nut 74 from rotating. Is moved to the center region R of the target assemblies 41 and 42 and pulled in the direction of the support plate 71 (lower side in FIG. 2), and the sputter surface 411 of the target 41 when not in use is substantially omitted. Can be horizontal. On the other hand, when the shaft portion 73 is moved to the processing substrate S side (upward in FIG. 2) while holding the nut 74 so as not to rotate, a pressing force is applied to the central region R of the target assemblies 41 and 42 to perform processing. As a result, the sputtering surface 411 of the target 41 when not in use can be made substantially horizontal. Thereby, the distance from the sputtering surface 411 of the target 41 to the processing substrate S can be made substantially constant over the entire surface, and the film can be formed on the processing substrate S with a substantially uniform film thickness without being affected by the warp of the target 41. .

  By the way, if the position of the magnet assembly 5 is fixed, the plasma density above the central magnet 52 is reduced, and the amount of erosion of the target 41 accompanying the progress of sputtering is reduced as compared with the periphery thereof. For this reason, it is preferable that the magnet assembly 5 is reciprocated in parallel and at a constant speed between two positions along the horizontal direction of the target 41 by driving means such as a motor (not shown). In this case, the opening 51 a formed in the support plate 51 of the magnet assembly may be formed in a long hole along the reciprocating direction of the magnet assembly 5.

  In the present embodiment, in order to provide a simple structure, the warp correction means 7 has been described as comprising support portions 71 and 72 provided behind the target assemblies 41 and 42 and a shaft portion 73. The present invention is not limited to this, and any form may be used as long as a tensile force or a pressing force can be applied to the central region R. Further, although the description has been given of the case where the four warp correction means 7 are provided, the number is not limited to this, and is appropriately set according to the area of the target 41, for example.

  In the present embodiment, the sputtering chamber 11 provided with one sputter electrode 4 has been described. However, in the case where a film is formed on the processing substrate S having a large area, as shown in FIG. For example, six sputtering electrode bodies 4 may be arranged in parallel to form a magnetron sputtering electrode C, and the sputtering apparatus 10 may be configured.

  In this case, the targets 41a to 41f are juxtaposed so that the unused sputtering surface 411 is positioned on the same plane parallel to the processing substrate S, and between the side surfaces 412 facing each target 41a to 41f. Does not have any components such as an anode or a shield. The outer dimensions of the targets 41a to 41f are set to be larger than the outer dimensions of the processing substrate S when the targets 41a to 41f are arranged side by side.

  Further, three AC power supplies 61, 62, 63 for applying an AC voltage are connected to each target 41a-41f, and magnet assemblies 5a-5f are arranged behind each target 41a-41f. . In this case, when one AC power supply 61 is allocated to two targets (for example, 41a and 41b) adjacent to each other and a negative potential is applied to one target 41a, the other target 41b is assigned to the other target 41b. A ground potential or a positive potential is applied.

  For example, when a negative potential is applied to one target 41a, 41c, 41e via each AC power supply 61, 62, 63 and a ground potential or a positive potential is applied to the other target 41b, 41d, 41f, the other target The targets 41b, 41d, and 41f serve as anodes, and plasma is generated between the targets (for example, 41a and 41b) connected to one AC power supply 61, 62, and 63, respectively, and a negative potential is applied. Sputtered targets 41a, 41c and 41e are sputtered. When the potentials of the targets 41a to 41f are switched according to the frequencies of the AC power supplies 61, 62, and 63, the other targets 41b, 41d, and 41f are sputtered, so that the targets 41a to 41f are alternately sputtered sequentially. The film is formed over the entire surface of the processing substrate S.

  Thereby, since it is not necessary to provide any components such as an anode and a shield between the targets 41a to 41f from which the sputtered particles are not emitted, the region where the sputtered particles are not emitted can be made as small as possible. As a result, coupled with the fact that the film is not affected by the warping of the target, the film thickness distribution in the processed substrate S surface can be made substantially uniform.

  In this case, as in the above-described embodiment, 2 along the horizontal direction of the targets 41a to 41f by the driving means D such as an air cylinder so that the erosion region can be obtained uniformly over the entire surface of each of the targets 41a to 41f. The magnet assemblies 5a to 5f are reciprocated integrally and in parallel between the positions (L point, R point). In this case, the magnet assemblies 5a to 5f may be attached to the drive shaft D1 of the drive means D.

  Further, when the magnet assemblies 5a to 5f are arranged side by side, the rod-like auxiliary magnet 8 is matched with the polarities of the peripheral magnets 53 of the magnet assemblies 5a and 5f located at both ends so that the magnetic field balance on both sides can be adjusted. The support portion 81 that supports the auxiliary magnet 8 is attached to the drive shaft D1 of the air cylinder D so as to move integrally with the magnet assembly 5. As a result, the magnetic flux density at both ends of the magnet assemblies 5a to 5f can be increased, the magnetic field balance can be improved, and the film thickness distribution in the surface of the processing substrate S and the film quality distribution when performing reactive sputtering can be made substantially uniform. .

  In this example, an Al film was formed on the processing substrate S using the sputtering apparatus 1 shown in FIG. In this case, a glass substrate (1200 mm × 1000 mm) is used as the processing substrate S, Al is used as the target 41, and it is manufactured to have an external dimension of 1400 mm × 1200 mm by a known method, and a copper backing plate 42 is used. Joined.

  In this case, using In as a bonding material, the target 41 and the backing plate 42 are placed on a heating plate and heated to 200 ° C., respectively, and after applying the bonding material to each bonding surface of the target 41 and the backing plate 42, The target assemblies 41 and 42 were bonded to each other and held in this state and naturally cooled.

  Then, the target assembly is attached to the frame 44 by the bolt B, the shaft portion 74 of the warp correction means 7 is attached to the back surface of the backing plate 42, and then the magnet assembly 5 is interposed via the shaft portion 74 using a level meter. The distance from the sputtering surface 411 of the target 41 to the processing substrate S was made substantially constant over the entire surface of the target S.

As sputtering conditions, argon (Ar flow rate 200 sccm), which is a sputtering gas, was introduced by controlling the mass flow controller 21 so that the pressure in the film forming chamber 11 evacuated was maintained at 0.3 Pa. Further, the input power to the target 41 was set to 40 kW, and the sputtering time was set to 30 seconds. The distribution of the film thickness along the horizontal direction of the glass substrate S when sputtered on the glass substrate S under these conditions is shown by a dotted line in FIG.
(Comparative Example 1)

  As Comparative Example 1, an Al film was formed on the processing substrate S using the sputtering apparatus 1 shown in FIG. In this case, the sputtering conditions and the like were the same as those in Example 1, but after the target assemblies 4, 1, 42 were produced and attached to the frame 44 with the bolts B, the warp was not corrected. The distribution of film thickness along the lateral direction of the glass substrate S when sputtered on the glass substrate S under these conditions is shown by a solid line in FIG.

  If it demonstrates with reference to FIG. 5, in the comparative example 1, both sides of a glass substrate (The film thickness (about 270 nm) in the outer periphery part of a glass substrate will become thick, and the thinnest part (about about the center area | region) In contrast, in Example 1, the film thickness is different between the central region of the glass substrate and the peripheral region thereof. It can be seen that the difference in thickness can be in the range of about 10 nm or less, and the uniformity of the film thickness can be improved.

The figure which illustrates roughly the structure of the sputtering device of this invention. The figure explaining arrangement | positioning of a curvature correction means. Sectional drawing along III-III of FIG. The figure explaining the other modification of the sputtering device of this invention. The graph which shows distribution of the film thickness along the horizontal direction of a process board | substrate when forming into a film by sputtering according to Example 1 and Comparative Example 1. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Magnetron sputtering apparatus 4 Sputtering electrode 41 Target 42 Backing plate 7 Warpage correction means S Processing substrate

Claims (6)

A target assembly having a sputtering target and a backing plate bonded to the back side of the sputtering surface of the target via a bonding material is provided, and the target assembly is extended outside the target of the backing plate. A sputter electrode that can be attached to the sputter electrode main body through a portion, wherein the attachment position of the backing plate to the sputter power source main body is located in the center region of the target assembly along the direction perpendicular to the horizontal plane. A sputter electrode provided with a warp correction means for applying either a tensile force or a pressing force. The warp correction means is composed of a support portion provided in the sputter power source body located behind the target assembly, and a shaft portion having one end screwed to the support portion. The sputter electrode according to claim 1, wherein the sputter electrode is detachably attached to a central region of the plate. The sputter electrode according to claim 1 or 2, wherein a plurality of the warp correction means are provided. A sputter electrode according to any one of claims 1 to 3 is arranged in parallel at a predetermined interval, and a plurality of sputter electrodes are provided behind each target assembly so as to form a magnetic flux in front of each target. A sputtering apparatus, comprising: a magnet assembly comprising: a magnet assembly; and an AC power source for alternately applying either a negative potential and a ground potential or a positive potential to each target. The sputtering apparatus according to claim 4, further comprising a driving unit that integrally drives the magnet assemblies so that the magnetic flux is movable in parallel with respect to the target. The magnet assembly has a support plate for supporting each magnet, and the support plate is provided with a long hole along the moving direction of each magnet assembly that allows the shaft portion of the warp correction means to be inserted. The sputtering apparatus according to claim 5.

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