JPS63221620A - Plasma treatment apparatus - Google Patents

Abstract

PURPOSE:To reduce cleaning time by providing a treatment chamber in which electrodes are provided, a gas supplier which supplies treatment gas into the treatment chamber, an evacuator which evacuates the treatment chamber to reduce the internal pressure to a required pressure and a cleaning electric source which has a specific frequency and is connected to the electrodes. CONSTITUTION:A power with a frequency less than 1 MHz is applied to electrodes by a cleaning power source. A switch 5 is connected to a high frequency source 4 side and a switch 6 is connected to a ground side. A wafer is placed on an electrode 2 and CHF3 is supplied to etch an SiO2 film formed on the wafer surface under a required pressure. In order to remove adhering deposits, a plasma cleaning is carried out. O2 gas is supplied into a treatment chamber 1 and the pressure in the chamber 1 is maintained at 0.1 Torr and the switches 5 and 6 are connected to a low frequency source 7 and a power with a frequency of 100 KHz is applied to the electrodes 2 and 3 to generate a plasma of O2 gas in the treatment chamber 1 for the plasma treatment.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a plasma processing apparatus, and particularly to a plasma processing apparatus suitable for plasma cleaning.

[Conventional technology]

As described in Japanese Patent Application Laid-Open No. 58-46639, a conventional device has a counter electrode that faces the mounting electrode on the side on which the sample is mounted, and has a surface that also faces the inner wall of the processing chamber. Some devices are made movable in a direction perpendicular to the electrode, and a high-frequency power source is connected to the opposing electrode to generate plasma, thereby cleaning the entire processing chamber with plasma.

[Problem that the invention seeks to solve]

The above conventional technology does not take into account the cleaning speed of plasma cleaning, and uses a high-frequency power source to generate plasma during cleaning, and uses ions and radicals in the plasma to remove deposits that have adhered to the inside of the processing chamber. Since it is a reaction-removal method and relies solely on reaction-based removal, there is a problem in that it takes a long time to clean.

An object of the present invention is to provide a plasma processing apparatus that can shorten cleaning time when cleaning using plasma.

[Means for solving problems]

The above purpose is to provide a processing chamber with an electrode inside, a gas supply device that supplies processing gas into the processing chamber, an exhaust device that reduces the pressure inside the processing chamber to a predetermined pressure, and a cleaning device with a frequency of 1 MHz or less that is connected to the electrode. This is achieved by having a power source.

[For production]

Cleaning gas is supplied into the processing chamber by a gas supply device, the pressure inside the processing chamber is reduced to a predetermined pressure for cleaning by an exhaust device, and the frequency is set to 1 MHz by a power source.
Apply the following power to the 1J71 pole.

As a result, plasma is generated in the processing chamber, and ions in the plasma are accelerated by electric power with a frequency of IMI-1x or less, and deposits attached to the inner wall of the processing chamber are removed by the shatter action, and ions and radicals in the plasma are Since deposits are also removed by reaction removal, the cleaning time when cleaning using plasma can be shortened.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS. 1 to 5.

FIG. 1 shows a plasma processing apparatus, in this case a g! It is a place. Electrodes 2 and 3 are provided facing each other in the processing chamber l, and a gas supply *l (not shown) is provided.
Processing gas is supplied via fi.

The barrel is evacuated to a predetermined pressure by an exhaust device (not shown). The electrode 2 is connected to a power source via a switch 5, in this case a high frequency power source 4 having a frequency of 13.56 MHz. Electrode 3 is grounded via switch 6. In addition, the other of switches 5 and 6 is connected to another power source for cleaning.
In this case, it is connected to a low frequency power source 7 with a frequency of 1°0 KHz, and is connected to electrodes 2 and 3 by switching switches 5 and 6.

With the device configured as described above, the switch 5 is connected to the high-frequency power #4 side, and the switch 6 is connected to the ground side.

A wafer is placed on the electrode 2, and in this case, CHF, for example, is supplied as a processing gas and the 5t02 film formed on the convex surface of the sea urchin is etched at a predetermined pressure.

This etching process causes C, CP, and other deposits to adhere to the inner wall of the processing chamber 1 and the surfaces of the electrodes 2 and 3. Next, plasma cleaning is performed to remove these deposits.

Plasma cleaning, in this case, the processing chamber! within 02
Gas is supplied and maintained at a pressure of 0.1 Torr, switches 5 and 6 are connected to the low frequency power source 7 side, and the electric MI! Apply power with a frequency of 100KHz to 2 and 3, and the processing chamber!
This is done by generating plasma of 02 gas inside the chamber. The 02 gas becomes a plasma state of 0 ions and 0 radicals, and the 0 ions and O radicals react with the deposits adhering to the inner wall of the processing chamber l to remove the deposits. Some of the energetic O ions collide with the deposits and remove the deposits by sputtering, making it possible to perform efficient plasma cleaning.

This was discovered by changing the frequency of the low frequency power source 7 and examining the relationship between one frequency and the cleaning speed. As shown in Figure 2, the cleaning speed improves as the frequency is lowered by one frequency. I understand. The cleaning speed in this case is measured at a point on the side wall A in the processing chamber l. At the frequency of 13°56 MHz when performing etching processing, the period of switching between positive and negative is short and energy sufficient to accelerate ions, which have a large mass compared to electrons, cannot be obtained, and a sputtering effect due to ions is obtained, so ions and The degree of cleaning is slow due to only reaction removal by radicals.

Also, the frequency at which ions begin to accelerate and move varies depending on the pressure generator voltage, etc., but is approximately 1 MHz.
It's from nearby.

Next, while keeping the frequency constant at 100 KHz, we investigated the relationship between the pressure inside the processing chamber 1 and the cleaning speed.
As shown in the figure, it was found that the cleaning speed improved from around 0.1 Torr to below. Furthermore, point B
and C is 02 gas at 500C due to the performance of the exhaust system.
Since the pressure could not be reduced to the specified pressure under the condition of 39 CC/min and 5 CC/min, the 02 gas member was
It was investigated by reducing the pressure to a predetermined pressure at CC/min. The reason why the cleaning speed improves is that the free path length of gas molecules becomes longer, which improves the sputtering effect of ions, and the reason why the cleaning speed decreases when the pressure is further reduced is because the free path length of gas molecules becomes longer, and the reason why the cleaning speed decreases is that ions and radicals I think this is because the amount of

In addition, the frequency is 13.56MH! In this case, as shown in FIGS. 4 and 5, the cleaning speed is the fastest (and the cleaning time is shortened) when the pressure is around 0.1 Torr.

However, the cleaning speed is much slower than when the frequency is lowered by one.

As described above, according to this embodiment, the frequency of the plasma generation power source during plasma cleaning can be as low as 1 MHz or less, so that in addition to reaction removal using ions and radicals, sputter removal using ions is also added, thereby shortening the cleaning time. Can be done.

Further, by lowering the processing pressure during cleaning to 0.1 Torr or less, there is an effect that the cleaning time can be further shortened.

Furthermore, in this embodiment, low frequency power is applied to both electrodes 2 and 3 to generate a discharge between them and the processing chamber 1, so that the entire inner wall surface of the processing chamber 1 and the electrodes 2 and 3 are
The plasma spreads not only to the back surface of the electrode 3 but also between the electrodes 2 and 3, making it possible to perform plasma cleaning over the entire interior of the processing chamber.

Note that in this example, low-frequency power is applied to both electrodes 2 and 3, but low-frequency power may be applied to one electrode, or the electrode to which low-frequency power is applied may be alternately changed. However, the cleaning speed can be improved in the same way.

In addition, in the embodiment, the high frequency power source 4 for processing the wafer and the low frequency tail 1IA7 for plasma cleaning are separated, but it is also possible to use the low frequency power source for processing the wafer. In the case of a good one, the electrode 2 may be connected to the low frequency power source 7 as shown in FIG. 6, and the switch 6 may be used to switch the electrode 3 between the low frequency tail R7 and the ground.

Further, in this embodiment, 02 gas is used as the processing gas for plasma cleaning, but it goes without saying that the deposits differ depending on the wafer processing and are determined by the deposits.

[Effects of the Invention] According to the present invention, there is an effect that the cleaning time when cleaning using plasma can be shortened.

[Brief explanation of the drawing]

Fig. 1 is a configuration diagram showing a plasma processing apparatus that is an embodiment of the present invention, Fig. 2 is a diagram showing the relationship between frequency and cleaning speed, and Fig. 3 is a diagram showing the pressure and cleaning when the frequency is set to 100 KHz. A diagram showing the relationship with speed, Figure 4 shows the frequency of 13.56
FIG. 5 is a diagram showing the relationship between pressure and cleaning speed in MHz, FIG. 5 is a diagram showing the relationship between pressure and cleaning time compared to FIG. 4, and FIG. 6 is another embodiment of the present invention. 1... Processing chamber, 2, 3... Electrode, 7.
...Low frequency power supply agent Patent attorney Masao Ogawa Figure 11 Waste ILL (KHz) Figure 3 β power (Tarr) O Figure 6

Claims (1)

[Scope of Claims] 1. A processing chamber having an electrode therein, a gas supply device for supplying processing gas into the processing chamber, an exhaust device for reducing and exhausting the inside of the processing chamber to a predetermined pressure, and connected to the electrode. A plasma device characterized in that it is equipped with a power source for cleaning at a frequency of 1 MHz or less. 2. The plasma processing apparatus according to claim 1, wherein the electrode is a parallel plate type electrode, and the electrode is connected to at least one of the parallel plate type electrodes. 3. The plasma processing apparatus according to claim 1, wherein the electrode is a parallel plate type electrode, and the power source can be connected to both electrodes of the parallel plate type electrode during plasma cleaning. 4. The plasma processing apparatus according to claim 1, wherein the pressure inside the processing chamber is 0.1 Torr or less.