JPH02288227A - Plasma treatment method and device therefor - Google Patents

Abstract

PURPOSE:To form and treat plasma stably even on the low pressure of a treating gas by specifying the pressure of a discharge gas in plasma treatment and variably setting supply power. CONSTITUTION:The pressure of a discharge gas can be set at the two stages of gas pressure (such as 10<-2>Torr level) capable of stably forming plasma and gas pressure (such as 10<-3>Torr level) at the time of actual treatment, and power fed to an electrode can also be set similarly at the three stages of a time when the power is increased when plasma is shaped, a time when the power is reduced in an extent that the quantity of treatment is not affected as discharge is kept as it is during setting at treating-gas pressure after the formation of plasma and power at the time of treatment. The formation of plasma is detected optically, an output is lowered as discharge is kept as it is in high-frequency power by a controller 15, a pressure regulating valve 9 is driven through a pressure regulator 14, and the pressure of the discharge gas is set at treating pressure. High-frequency power is also set at a value at the time of treatment, and the rise of discharge is completed while the measurement of the time of sputtering and etching treatment is started.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a plasma processing method and apparatus for forming a thin film or etching using direct current or high frequency discharge, and particularly to a plasma processing apparatus for performing the processing in a place where the discharge gas pressure is low. The present invention relates to a plasma processing method and apparatus suitable for various cases.

[Conventional technology]

Processing apparatuses using direct current or high-frequency discharge include sputter film forming apparatuses, sputter etching apparatuses, and plasma CVD apparatuses. In recent years, the high performance and
For the purpose of increasing speed, substrate wafers are becoming larger in size along with miniaturization and higher integration, and semiconductor manufacturing equipment is also being developed to meet these demands. Japanese Patent Application Publication 1986-
Taking the dry etching apparatus shown in No. 123034 as an example, by introducing a magnetic field, a large area wafer can be etched at high speed and uniformly at low gas pressure.

In addition, as an example of a sputtering film forming apparatus, the Applied Physics 1988
As described on pages 19 to 31 of the September issue, processing at low gas pressure is used to reduce damage to the device and storage of discharge gas in the film.

[Problem to be solved by the invention]

In the conventional technology mentioned above, these devices that perform film forming or etching processing tend to perform plasma processing at low gas pressure, and at this processing gas pressure, direct current or high frequency power is supplied to the electrodes of the processing device to start discharge. However, there is a problem in that plasma cannot be stably formed as in the case of conventional processing gas pressures. In addition, using microwaves as in the sputtering film-forming equipment mentioned above allows plasma to be formed at low gas pressure, but this requires power supply equipment such as a microwave power source and waveguide, which increases equipment costs. There is a problem in that as the price increases, the dedicated space also increases.

SUMMARY OF THE INVENTION An object of the present invention is to provide a plasma processing method and apparatus capable of stably forming plasma even in low gas pressure processing using a conventional processing apparatus using direct current or high-frequency discharge.

[Means to solve the problem]

In order to achieve the above object, in the plasma forming method of the present invention, the discharge gas pressure is set to a gas pressure at which plasma can be stably formed (e.g., 10-'' Torr range) and a gas pressure during actual processing (e.g., 10-'' Torr range). Similarly, the power supplied to the electrode is large during plasma formation, and while the processing gas pressure is set after plasma formation, the discharge is maintained while the processing amount is affected. It is so small that it does not cause any damage, and it can be set to three levels of power during processing.

In addition, the plasma processing apparatus of the present invention includes an electrode unit that performs sputtering film formation or sputter etching treatment by electric discharge, a vacuum reaction chamber equipped with this electrode, a vacuum pump connected to one reaction chamber and evacuated, and a vacuum pump that evacuates the reaction chamber. a vacuum gauge for measuring the temperature, a discharge gas supply device, a pressure regulating valve unit installed between the reaction chamber and the vacuum pump to keep the pressure of the discharge gas supplied to the reaction chamber constant, and a direct current or Consists of a power supply unit that supplies high-frequency power and a control device that automatically controls each of the above units. While supplying discharge gas under certain conditions to the evacuated reaction chamber, pressure is increased by plasma formation commands from the control device. It is configured to drive a regulating valve unit and a power supply unit.

[Effect]

In the present invention, the discharge gas pressure and the electric power supplied to the electrode unit can be set variably, so that when plasma is to be formed, the discharge gas pressure is processed by the pressure regulating valve unit according to a command from the control device. Since the voltage is set higher than the pressure and the power is also larger, plasma can be stably formed.

In addition, after plasma formation, the discharge is maintained even if the power is reduced, so the power is set to a small value, the gas pressure is set to the processing pressure, and then the power is set to the value at the time of processing and processing is performed. This allows predetermined processing to be performed.

〔Example〕

The present invention will be explained below with reference to the drawings. FIG. 1 shows the overall structure of a sputter etching apparatus using high frequency discharge, which is an embodiment of the present invention. An anode electrode 3 having a magnet unit 2 and a cathode electrode 5 insulated from earth by an insulator 4 are attached to the vacuum reaction chamber 1 . A sample 6 is placed on the sword electrode 5 , and is further connected to a high frequency power source 8 via an impedance matching device 7 . Also, there is pressure in reaction chamber 1! A vacuum pump 10 and a discharge gas cylinder 12 are connected via a 131 valve regulator 9 and a discharge gas supply device 11, respectively.

Note that the pressure regulating valve 9 is a vacuum gauge 1 attached to the reaction chamber 1.
3 and is connected to a pressure regulator 14. moreover,
The control device 15 uses high frequency electric g8. discharge gas supply device 11,
and pressure regulator 14, respectively. FIG. 2 shows an example in which a wafer having a thermal oxide film formed on its surface was subjected to sputter etching using the apparatus having the structure described above. From this result, the etching speed is high and the etching uniformity is good when the gas pressure of Ar, which is the discharge gas, is low.In the case of this example, the etching speed and uniformity are the highest when the Ar gas pressure is 0.27Pz. It can be seen that the results are good. However, at this pressure, plasma cannot be formed even if the radio frequency power is increased.

Therefore, a plasma forming method according to an embodiment of the present invention will be explained with reference to FIGS. 1 and 3.

In FIG. 1, the reaction chamber 1 is evacuated by the vacuum pump 10.
First, the control device 15 issues a discharge start-up command to the pressure regulating valve 9 via the pressure regulating device 14. A discharge gas (Ar) cylinder 12 and a discharge gas supply device 11 supply discharge gas to a predetermined pressure (see the peak in FIG. 2).

Based on this result, the control device 15 issues an output command to the high frequency power source 8 to supply the power necessary for starting the discharge to the cathode electrode 5 via the matching device 7 (point (b) in FIG. 2). After optically detecting the formation of plasma (not shown), the control device 15 reduces the output of the high-frequency power while maintaining the discharge (point (c) in Figure 2), and further reduces the output of the high-frequency power by the pressure adjustment device 14.
The discharge gas pressure is set to the processing pressure by adjusting the pressure regulating valve 9 through the pressure control valve (point (d) in Fig. 2), and the high-frequency power is also set to the value for processing (point (e) in Fig. 2). Point) At the same time as finishing the discharge start-up, start measuring the time of the sputter etching process.

After the predetermined processing time has ended (point (f) in Figure 2), the high frequency power is reduced again while maintaining the discharge as shown in Figure 2 (g).
), the discharge gas pressure was increased to the same pressure as at the start of discharge (point (h) in Figure 2), and the high-frequency power was also increased to the same value as at the start of discharge (point (i) in Figure 2). Point) The power supply is stopped, the discharge gas supply device 11 is closed, and at the same time, the pressure regulating valve 9 is fully opened and the reaction chamber 1 is evacuated by the vacuum pump IO. The reason why the power supply is stopped after setting the same discharge gas pressure and high-frequency power as at the time of starting the discharge at the time of stopping the discharge is that by setting the impedance setting value of the matching device 7 to the same value as at the time of starting the discharge, This is because when repeated sputter etching processes are performed, the impedance adjustment range of the matching device becomes smaller, making it possible to stably form plasma.

Note that plasma can be formed in exactly the same manner using a sputtering film forming apparatus using high-frequency discharge.

Next, another embodiment of a sputtering apparatus using direct current discharge will be described with reference to FIG. The vacuum reaction chamber 1 has a magnet unit 2, a conductive target 41 is fixed on the surface, a cathode electrode 43 is insulated from the ground by an insulator 42, and a sample 6! ! An anode electrode 44 is attached thereto. Note that the cathode electrode is connected to a DC power source 45. Also.

A vacuum pump IO or a vacuum pump IO is connected to the reaction chamber 1 via a pressure regulator.
In addition, a discharge gas cylinder 12 is supplied via a discharge gas supply device 11.
are connected to each other. Note that the pressure regulating valve 9 is connected to the pressure regulating device 1 together with the vacuum gauge 13 attached to the reaction chamber 1.
Connected to 4. Furthermore, the control device 15
5. It is connected to the discharge gas supply device 11 and the pressure adjustment device 14, respectively. A plasma forming method using the apparatus configured as described above will be explained with reference to FIGS. 4 and 5. In FIG. 4, a discharge start-up command is sent from the controller 15 to the reaction chamber 1, which has been evacuated by the vacuum pump IO, through the pressure regulator 14 and the pressure regulating valve 9. The discharge gas is supplied to a predetermined pressure by the discharge gas cylinder 12 and the discharge gas supply device 11 (see the peak in FIG. 5). Based on this result, the control device 5 issues an output command to the DC power @ 45 to supply the power necessary for starting the discharge to the cathode electrode 43.
(point (b) in Figure 5). After optically detecting the formation of plasma, the DC power supply power applied to the control device 15 is reduced in output while maintaining the discharge (point (c) in FIG. 5), and is further connected to the pressure regulating valve 9 via the pressure regulating device 14. (point (d) in Figure 5) to set the discharge gas pressure to the processing pressure by opening the
The DC power supply power is also set to the value used for processing (see Figure 5).
Point e)) At the same time as the discharge start-up is completed, time measurement of the sputter deposition process is started.

After the predetermined processing time has ended (point (f) in FIG. 5), the control device 15 stops the DC power supply, and at the same time closes the discharge gas supply device 11, the pressure regulating valve 9 is fully opened and the vacuum pump 10 The reaction chamber 1 is evacuated.

〔Effect of the invention〕

According to the present invention, since the discharge gas pressure and power supply in plasma processing can be variably set, it is possible to stably form plasma and perform processing even when the actual processing gas pressure is low.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of the plasma processing apparatus of the present invention, FIG. 2 is a diagram showing experimental results for the apparatus shown in FIG. 1, and FIG. 3 is a diagram showing the plasma processing method of the present invention using high-frequency discharge. FIG. 4 is a configuration diagram showing another embodiment of the plasma processing apparatus of the present invention, and FIG. 5 is an explanatory diagram when the plasma processing method of the present invention is applied to DC discharge. . 1016 reaction chamber, 6...sample, 8...
High frequency power supply, 9...pressure regulating valve, 11...
Discharge gas supply device, 14... Pressure adjustment device, 15...
-Control device, 45...DC power supply.

Claims (1)

[Claims] 1. Supplying a discharge gas to a vacuum processing chamber, supplying power to one of the opposing electrodes, forming plasma at a discharge gas pressure of 10 mTorr or more, and plasma processing the substrate at a pressure of less than 10 mTorr. A plasma processing method characterized by performing. 2. The plasma processing method according to claim 1, wherein the sputter etching is performed using high frequency power. 3. The plasma processing method according to claim 1, wherein the sputter deposition is performed using high frequency power. 4. The plasma processing method according to claim 1, wherein the sputter deposition is performed using DC power. 5. An electrode facing the vacuum processing chamber and a discharge gas supply section;
A plasma processing apparatus comprising a discharge gas pressure adjustment means, a power supply device, and a discharge gas pressure and supply power control means, and the plasma processing gas pressure and processing power are set after plasma is formed. . 6. The plasma processing apparatus according to claim 5, wherein sputter etching is performed using high frequency power. 7. The plasma processing apparatus according to claim 5, wherein sputter deposition is performed using high frequency power. 8. The plasma processing apparatus according to claim 5, wherein the sputter deposition is performed using DC power.