JPH049465A - Method and device for controlling dc potential in thin film forming device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a thin film processing technology using high frequency glow discharge, and in particular, uses a high frequency power source to process a capacitively coupled discharge electrode and/or an object to be processed on the electrode. The present invention relates to a method and apparatus for forming or processing a thin film by forcibly controlling the direct current potential (self-bias) generated on the surface to a desired value.

Note that the DC potential (self-bias) in the high-frequency glow discharge mentioned above is the direct current potential (self-bias) in the glow discharge when performing thin film processing such as deposition, etching, and ashing of electrically insulating substrates and electrically insulating thin films. It is necessary to accelerate the ions in the plasma to the surface of the object to be processed.
In response to the recent demands for high-performance thin film devices, the importance of controlling the potential on the surface of the processing object is increasing.

[Prior Art] A first conventional technology uses a high frequency power source for thin film processing such as deposition, etching, and ashing of electrically insulating substrates and electrically insulating thin films, The DC potential generated on the surface of the object to be processed is controlled by adjusting the output power (travelling wave power) of the high frequency power source.

As a second prior art technique that is closest to the object of the present invention, as described in Japanese Unexamined Patent Publication No. 1-180970, a DC (direct current ) Connect to the power supply and connect this D
There is a technique for controlling the DC potential generated on the capacitively coupled discharge electrode and the surface of the object to be processed on the electrode to a desired value by adjusting the output voltage of the C power source.

[Problems to be Solved by the Invention] Among the industrial frequencies assigned to Japan, the frequencies suitable for generating glow discharge plasma are 13.560 MHz, 27.
120MHz, 40.68MHz, but - numerically,
The frequency of the high frequency power source is often 13.560 MHz.

The problem with the above-mentioned first conventional technique is that, as a result of testing, the DC potential generated on the surface of the object to be treated on the discharge electrode was -200V.
When controlling from to the positive side, the power adjustment range of the 13.560MHz high frequency II source is about 20 to 2W, so if the power adjustment means does not have high resolution, the controllable DC potential will be a rough value. Put it away. In addition, even if the output is lowered to 2 WUi of the minimum high-frequency output power that can barely maintain glow discharge, the DC potential generated on the surface of the object to be processed is -70
It was also about V, and it was impossible to control it to the positive side beyond this.

For reference, FIG. 5 shows the DC potential of the discharge electrode and the surface of the glass substrate to be processed when the high-frequency output power (travelling wave) is varied from 0 to 20 W using this first conventional technique. Shows the relationship between DC potential.

Furthermore, the values of the above test results vary greatly depending on the surface area ratio of the discharge electrode and the ground side rod, the pressure of the working gas used to generate glow discharge, the matching state of the high frequency matching device, etc.
Hou i11! If there is no monitoring means for detecting the DC potential generated on the surface of the finest object to be processed, there is a drawback that it cannot be controlled to a desired value.2 The problem with the above-mentioned second conventional technique is as described in Japanese Patent Application Laid-Open No. 1-180970. As described in the examples, the frequency of the high frequency power source was 210 MHz.

100MHz is selected, but these frequencies are not industrial frequencies assigned to Japan, so radio noise prevention means are required for industrial use at high output, and - Since the frequency is not specified, it is necessary to manufacture a dedicated high frequency power supply and high frequency matching device.
The drawback is that it is complicated and expensive despite its performance.

Sarani, 13.560MHz (7) High frequency 1fili
i! The control range of the DC potential value generated on the surface of the electrical insulator to be processed on the radiation pole is -76 to -. It could only be controlled within a very narrow range of 122■.

For reference, FIG. 6 shows the DC bias when tested using a 13.560 MHz high frequency power supply, a matching device, and a high frequency filter, and in accordance with the second prior art. Set the output power of the power supply to 0
The relationship between the DC potential of the discharge electrode, the DC potential of the surface of the glass substrate to be processed, and the output current of the DC bias power supply when changed to -300V is shown.

As can be seen from the above, the conventional technologies of 1 and 2 are:
The drawback is that it can only be expected to be effective in a special frequency band that has not been allocated to Japan as an industrial frequency.

As described above, the present invention uses high-frequency TIs to accelerate ions in a glow discharge plasma to the surface of an object to be processed when depositing an electrically insulating substrate or electrically insulating thin film, or performing thin film processing such as etching or ashing. The control range of the capacitively coupled discharge necessary for ,and,
It is an object of the present invention to provide a high frequency discharge electrode with excellent cost performance and controllability, and/or a DC potential control method and device generated on the surface of an object to be treated on the electrode.

[Means for Solving the Problems] In the present invention, in order to solve the above problems, in a thin film processing apparatus that utilizes high-frequency glow discharge, a low-pass filter (low-pass filter) is provided to an electrode that supplies high-frequency power. A power consumption means (sliding resistor, electronic load device, etc.) is connected through the connector to adjust the resistance value or DC inflow current.

[Operation] In a thin film processing device that uses high-frequency glow discharge, a power consumption means, such as a sliding resistor, is connected to the electrode to which high-frequency power is supplied via a low-pass filter, and the high-frequency glow discharge occurs at the maximum resistance value of the power consumption means, such as a sliding resistor. Start. At this time, the high frequency output power is set so that the DC potential generated on the surface of the capacitively coupled discharge electrode or the object to be processed on the electrode reaches the maximum absolute value on the negative side of the desired control range. After that, when the resistance value is adjusted in the direction of decreasing, the radiation t1 caused by the difference in mobility between ions and electrons in the high-frequency glow discharge plasma
The value of the DC potential generated on the i-electrode and the surface of the object to be processed on the electrode changes from the maximum negative absolute value to the positive side. This is because as the resistance value decreases, only the direct current component increases from the electrode through the low-pass filter. Also,
The DC potential generated on the surface of the object to be processed on the electrode also changes from the maximum negative absolute value to the positive side. This is due to the electrostatic capacitance determined by the shape and dielectric constant of the object to be processed, and when the high-frequency current flows through this, an AC potential difference is maintained between the surface of the object to be processed and the electrode. Can follow DC component potential. Furthermore, when the resistance value is set to 0Ω, the electrode DC potential can be controlled to O[V], and the DC potential of the surface of the object to be treated on the electrode can be controlled to about -25V, and even in this state, the density of the high-frequency glow discharge plasma is Although it depends on the high frequency power input to the electrode and the maximum impedance (resistance value) of the power consumption means, the resistance value is usually maintained at about 70% of the maximum resistance value. Therefore, if the present invention is applied to a thin film deposition apparatus,
High ion density and low energy ion-assisted film formation (a technology in which thin film particles are formed while being bombarded with ions) is possible.

[Example] An example in which the present invention is applied to a sputtering apparatus, which is a thin film deposition apparatus, is shown in FIGS. 1 and 2, and
Automatic side of power consumption means! An embodiment equipped with the II device will be described below with reference to FIG.

In Figures 1 to 3, ] is a 13.560 MHz high frequency S source device for substrate electrodes, 2 is a high frequency matching device for substrate electrodes that performs impedance matching between the 1i source side and the load side, and 3 is a substrate 4 mounted. 4 is a substrate, 5 is a target made of a film-forming material, 6 is a target electrode on which the target 5 is placed and has a water cooling mechanism, lo is a high-frequency discharge electrode for a substrate that is water-cooled or heated to maintain a predetermined temperature; A low-pass filter (low-pass filter) that passes only the DC component from the applied substrate 1i pole 3; 11 is a noise filter that cuts high-frequency noise; 12 is used as necessary; A shield plate 13 blocks out high frequency radiation noise, and 13 is the number of substrate poles 3 caused by the difference in mobility between ions and electrons in high frequency glow discharge plasma.
and a sliding resistor 14, which is one of the power consumption means for controlling the DC potential (self-bias) generated on the surface of the substrate 4 on the electrode; Current monitor means for detecting current, 1
5 is a voltage monitor means for detecting the potential of the DC component of the substrate electrode 3, which is used as necessary; 21 is 13.560M;
22 is a high frequency matching device for target electrodes that performs impedance matching between the power supply side and the load side; 23 is a high frequency radiation w'rIi pole for the target on which the target 5 is mounted and has a water cooling mechanism; 24 25 is a low-pass filter (low-pass filter) that can pass only the DC component from the target electrode 23 to which high-frequency power is applied; 25 is a noise filter that cuts high-frequency noise; 26 is used as necessary; 27 is a sliding resistor which is one of the power consumption means for controlling the direct current potential generated on the target discharge electrode 23 and the surface of the target 5 on the electrode; A current monitor means for detecting the DC component current flowing into the power consumption means 27, which is used as necessary, and 29 is a target electrode 2, which is used as necessary.
3 voltage Tanabata means for detecting the potential of the DC component; 30 a vacuum container; 32 a water pipe for cooling the inside of the target 5 and the target electrode 23; 33 connecting the target electrode 23 to the vacuum container 30; 34 is an anode ring provided to adjust the plasma potential used as necessary; 35 is for supplying power to the anode link 34 from a power source outside the vacuum vessel. current introduction terminal, 36
38 is an insulator for electrically insulating and fixing the anode link 34 to the vacuum container 30; 38 is a board ground shield; 39 is a board electrode 3 and a board ground shield 38;
40 is a mass flow control valve for introducing sputtering gas, 41 is an exhaust device for evacuating the inside of vacuum container 30, 50 is a high-voltage power source for sputtering, 51 60 is a control device that automatically controls the DC potential generated on the surface of the high-frequency discharge electrode or the object to be processed on the electrode to a set value; and 61 is one of the power consumption means. A sensor is shown for detecting the position or value of a sliding resistor.

FIG. 1, which consists of the above-mentioned components, shows a first embodiment of the present invention, in which the present invention is applied to the substrate electrode side of a sputtering apparatus, and the entire apparatus operates as follows.

Place the substrate 4 on the high frequency electrode 3 for substrate! After that, exhaust device 4
1, the inside of the vacuum container 30 is evacuated to a predetermined background (high vacuum), and at the same time, the temperature of the high-rise substrate electrode 3 is controlled to maintain the substrate 4 at a predetermined temperature. after that,
Argon gas for sputtering is introduced through the mass flow control valve 40 and adjusted to a predetermined gas pressure. When power is supplied from the target electrode 6t electrically connected to the target 5\sputtering high-voltage power source 50, high-density plasma for sputtering (not shown) is generated on the target 5, and in this high-density plasma The argon gas ions are accelerated by cathode fall and collide with the target 5, knocking out target atoms.

At this time, adjust the resistance value of the sliding resistor 13 to the maximum position, increase the output power of the high frequency power source 1 for substrate electrodes while performing matching with the high frequency matching device 2, and increase the output power of the high frequency power source 1 for substrate electrodes or the substrate on the discharge electrode 3 for substrates. 4 Adjust the output power to a point where the direct current potential generated on the surface becomes a value slightly larger than the desired absolute value on the negative side. Then refer to the voltage monitoring means 15, or
A current that refers to a means (not shown) that monitors the potential of the surface of the substrate that is the object to be processed, or detects a current that flows into a power consumption means that is correlated with the substrate surface potential that has been investigated in advance. Referring to the monitoring means 14, the resistance value of the sliding resistor 13 is decreased and accurately controlled to a desired value.

By the above sputtering operation, the ejected target atoms are deposited on the surface of the substrate 4, and at the same time, they are accelerated by the potential difference between the substrate surface potential of the DC component and the plasma potential (plasma potential) controlled by the above substrate bias operation. Positively ionized argon gas ions and target atoms in the plasma near the substrate 4 collide with the surface of the substrate 4, resulting in an ion-assisted film formation function (ions give migration to the thin film particles deposited on the substrate, forming a dense film). technology that enables control of film quality such as film strength, film stress, and crystallinity). Important control factors in this ion-assisted film formation technology are the acceleration energy of the ions irradiated onto the substrate 4 and the number of ions (more precisely, the number of sputtered target particles deposited on the substrate and the number of ions irradiated onto the substrate). The ratio of the number of ions is A), and the better the independent controllability of the acceleration energy of ions irradiated to the substrate 4 and the number of ions, the more it can be applied to a wide range of new functional thin films. For example, board 4
When forming a film by increasing the number of ions irradiated and lowering the acceleration energy, the output power of the above-mentioned high-frequency power source for substrate electrodes is increased to increase the plasma concentration near the substrate 4, which is directly related to the number of ions. The density may be increased and the resistance value of the sliding resistor 13 may be reduced. In addition, in order to accurately control the number of ions to a desired value, an ion monitor (not shown) that detects the number of ions, such as a Langmire probe, is installed near the substrate 4, and this value is measured. However, the output of the high frequency St source may be adjusted by "η".

In other words, the number of ions near the object to be treated is controlled by high-frequency power supplied to the discharge electrode, and the acceleration energy of the ions incident on the object to be treated is determined by adjusting the power consumption means connected to the discharge electrode via a low-pass filter. bias can be controlled independently.

FIG. 2 shows a second embodiment of the present invention, in which the present invention is applied to the target electrode side of a sputtering device, and operates as follows.

After placing the substrate 4 on the substrate electrode 3, the exhaust device 41 evacuates the inside of the vacuum container 30 to a predetermined background level, and at the same time controls the temperature of the substrate electrode 3 to remove the substrate 4.
to maintain the specified temperature. Thereafter, argon gas for sputtering is introduced through the mass flow control valve 40 and adjusted to a predetermined gas pressure. At this time, the high-frequency power source 21 for the target electrode is adjusted to the position where the resistance value of the sliding resistor 27 is maximum, and the high-frequency power source 21 for the target electrode is matched with the high-frequency electrode 23 for the target electrically connected to the target 5 using the high-frequency matching device 22. When output power is supplied, sputtering plasma (not shown) is generated on the target 5, and the argon gas ions in this plasma are accelerated by the negative DC potential generated on the target surface and collide with the target 5. Knock out atoms. A DC potential generated on the target open-emitting at pole 23 or on the surface of the target 5 on the electrode.

By adjusting the resistance value of the sliding resistor 27, it is accurately controlled to a desired value. When adjusting the resistance value, the first
Referring to the voltage monitoring means 29 as in the embodiment of
Alternatively, refer to a means (not shown) for monitoring the potential on the surface of the target that is the object to be processed, or detect the current flowing into the power consumption means that is correlated with the target surface potential investigated in advance. This may be done while referring to the current monitoring means 28. By controlling the DC potential generated on the surface of the target 5, it is possible to change the sputtering rate and slightly adjust the film formation rate, and also to control the kinetic energy of the ejected target atoms.
It can also be applied to film formation in which damage is avoided during the process of depositing on the substrate 4.

FIG. 3 shows a third embodiment of the present invention, in which the resistance value or
Based on the signal that monitors the DC component inflow current or the DC component potential generated in the high-frequency discharge electrode 5, the DC potential generated on the desired (set) high-frequency discharge electrode or the surface of the object to be treated on the electrode is adjusted. The device is equipped with a control device that automatically controls the power consumption means (sliding resistor, electronic load device, etc.) so as to achieve the desired results, and operates as follows.

All or part of the DC potential generated on the high-frequency discharge electrode or the surface of the object to be processed on the electrode, the resistance value that is various monitor signals, the DC inflow current, and the DC potential generated on the high-frequency discharge electrode. Find the correlation in advance (determine the transfer function in classical control theory, and find the state equation in modern control theory),
Program the control device 60. For example, a signal from the resistance value detection sensor 61 that detects the resistance value of the sliding resistor from the rotation angle of the drive actuator, a signal from the current monitor means 14 that detects the DC component current flowing into the power consumption means,
Voltage monitor means 15 for detecting the DC component potential of the discharge electrode
The control device 6o automatically controls the drive actuator of the power consumption means 13 by giving a signal to the drive actuator of the power consumption means 13 so that the set value is achieved based on all or some of the signals. In addition to the various monitor signals mentioned above, for example, the output power of a high frequency power supply,
High frequency 1 is the output voltage peak value of the source, gas pressure, 1! Signals such as the distance between poles may be additionally used, and the present invention is not limited to that shown in FIG. 3.

In addition, in FIGS. 1 to 3 which are examples of the present invention,
Substrate transport means, substrate movement means, substrate rotation means, reactive sputtering gas introduction means shutter, view boat,
Although a vacuum gauge and the like are not shown, they can be used if necessary. In addition, although a sliding resistor is shown as a power consumption means, for example, an electronic load device or the like can also be used.
The configuration is not limited to the configuration shown in FIG. 3.

Furthermore, although FIGS. 1 and 2 show an example in which the present invention is applied to one electrode of a sputtering device, which is one type of thin film forming device, the present invention is not limited to this.
It can be applied to both substrate electrodes and target electrodes as needed, and is not limited to sputtering equipment; plasma CVD (chemical vapor deposition method using plasma).

Among thin film processing technologies that utilize high-frequency glow discharge such as etching equipment and ashing equipment, it is particularly desirable to use a high-frequency power source and generate a DC potential on the surface of a capacitively coupled discharge electrode and/or the object to be processed on the electrode. It can be applied to a method and apparatus that performs thin film formation or thin film processing by forcibly controlling so that the value is the same.

FIG. 4 shows an example of the present invention shown in FIG. 1, in which the resistance value of the sliding resistor, which is one of the power consumption means, is adjusted to adjust the potential of the DC component of the discharge electrode from O to -. The figure shows the relationship between the DC potential of the discharge electrode, the DC potential of the surface of the glass substrate to be processed, and the current value of the DC component flowing into the sliding resistor when the voltage is varied up to 300V. The main conditions are: discharge gas pressure of 20 m torr (argon), distance between electrodes of 60 mm, electrode dimensions of φ144 mm, vacuum vessel inner dimensions of $250 x 240 H mm, 13.560 M.
The experiment was conducted with the Hz high frequency output power (traveling wave) constant at 120W.

As is clear from a comparison between FIG. 4, which shows the test results of the present invention, and FIG. 6, which shows the test results of the prior art, in FIG. The control range of the generated DC potential is very narrow, from -76 to -122mm, whereas in Figure 4, the control range of the DC potential generated on the surface of the glass substrate on the electrode is -25mm. It has a wide range of ~-290V and follows the discharge electrode potential, which is easy to monitor, with a difference of about ±20V. Although not shown, if the output power (traveling wave) of the high-frequency power source is constant at 200 W and other conditions are the same, the control range of the DC potential generated on the surface of the glass substrate is -2
It further spreads from 7 to -510V. Furthermore, the output power (traveling wave) of the high frequency power supply was set to be constant at 400W, and the resistance value was set to OΩ.
When the DC potential of the discharge electrode is adjusted to O[V], the DC potential generated on the surface of the glass substrate becomes -29V, and the number of ions incident on the glass substrate at this time is approximately 1.2X1.
016 pieces/see.

[Effects of the Invention] According to the present invention, in a thin film processing apparatus that utilizes high-frequency glow discharge, the DC potential generated on the surface of a capacitively coupled discharge electrode or the object to be processed on the electrode that supplies high-frequency power can be controlled over a wide range. It is possible to control the direct current potential of the surface of the object to be processed on the electrode so that the number of ions incident on the surface of the object to be processed is greatly increased and the acceleration energy of the ions is a small value of about 30 eV. Therefore, if the present invention is applied to a thin film deposition apparatus, ion-assisted film formation (a technique for forming a film while hitting the thin film particles being deposited with ions) with high ion density and low energy becomes possible. Further, if applied to thin film processing such as etching and ashing of electrically insulating substrates and electrically insulating thin films, it becomes possible to perform processing with low damage. In addition, the technology of the present invention is suitable for generating glow discharge plasma at the industrial frequency assigned to Japan, and uses a high frequency power source and a high frequency matching device whose frequency is 13.560 MHz, which is numerically frequently used. fulfill a function.

[Brief explanation of the drawing]

FIG. 1 shows a first embodiment of the present invention, and is a schematic cross-sectional view of the entire device when applied to the substrate electrode side of a sputtering device, which is one of the thin film forming devices. The second embodiment is a schematic cross-sectional view of the entire device showing the configuration when applied to the target electrode side of the same sputtering device, and FIG. 3 is a third embodiment of the present invention. The desired (
The case is equipped with a control device that automatically controls the power consumption means (sliding resistor, 1I load device, etc.) so that the DC potential generated on the surface of the high-frequency discharge electrode or the object to be processed on the electrode is set. FIG. 4 is a schematic diagram showing the main components to be explained, and the resistance value of the sliding resistor, which is one of the power consumption means, is adjusted for the first embodiment of the present invention shown in FIG. and set the potential of the DC component of the discharge electrode to O~-300.
Figure 5 is a diagram showing the relationship between the DC potential of the discharge electrode, the DC potential of the surface of the glass substrate to be processed, and the current value of the DC component flowing into the sliding resistor when changed to V.
With conventional technology, high frequency output power (traveling wave) can be reduced to
A diagram showing the relationship between the DC potential of the discharge electrode and the DC potential of the surface of the glass substrate to be processed when changed to 0W,
FIG. 6 shows a second conventional technique using a 13.560 MHz high frequency power supply, a matching device, and a high frequency filter.
Others are DC when tested according to the second prior art.
FIG. 3 is a diagram showing the relationship between the DC potential of the discharge electrode, the DC potential of the surface of the glass substrate to be processed, and the output current of the DC bias power supply when the output voltage of the bias power supply is varied from 0 to -300V. l... High frequency power supply device for substrate electrodes, 2... High frequency matching snowmaking for substrate electrodes, 3... High frequency 1i electrodes for substrates, 4... Substrate, 5... Target,
6... Target electrode, 10.24... Low pass filter, 11.25... Noise filter, 12.26... Shield treatment, 13.27... Sliding resistor, 14.28. ...Current monitor means, 15.29...Voltage monitor means, 21...High frequency power supply device for target electrode, 22...
- High frequency matching device for target electrode, 23... High frequency discharge electrode for target, 30... Vacuum container, 3
2... Water piping, 33.36.39... Insulator, 34... Anode ring, 35... Current introduction terminal,
38... Earth shield for substrate, 40... Mass flow control valve, 41... Exhaust device, 50
... High voltage power supply for sputtering, 51 ... Anode bias power supply, 60 ... Automatic control device, 61 ... Sensor for detecting the value of power consumption means. Patent applicant: Ube Industries, Ltd. Figure 2 Figure 1 Figure 3 Figure 5 Test conditions; Vacuum container: φ250 x 24L)? - Figure 4 test conditions: Figure 6 test conditions; High frequency chamber crab 5W (traveling wave) constant

Claims (2)

[Claims] (1) In a thin film processing device that utilizes high-frequency glow discharge, the high-frequency discharge electrode and , or a DC potential control method for a thin film processing apparatus, comprising forcibly controlling a DC potential generated on the surface of an object to be processed on an electrode. (2) In a thin film processing device that uses high-frequency glow discharge, a power consumption means is connected to the electrode that supplies high-frequency power via a low-pass filter, and a sliding resistor whose resistance value can be adjusted is connected to this low-pass filter. A DC potential control device for a thin film processing apparatus, characterized in that the DC potential control device is connected to and provided with a high frequency power control device capable of adjusting a DC component inflow current.