JPS58171821A - Detection of contamination and purification degree in plasma processing and apparatus thereof - Google Patents

Abstract

PURPOSE:To improve detection accuracy by detecting contamination and purification degree in the plasma apparatus from a current or voltage value applied to the detecter from discharged plasma. CONSTITUTION:A metal 5 such as platinum covered with an insulator 3 such as quartz and is exposed at the surface 4 within a plasma apparatus is mounted to an internal wall 2 of a dry etching apparatus 1 and a voltage applying circuit 6, a current measuring circuit 7 and an earth 8 are coupled thereto. Immediately after the purification, namely after start of discharging, a film of decomposed product of gas used for dry etching is adhered to the surface of detecter. Therefore, a current does not flow. However, the film is ashed by the oxygen plasma with time and the film becomes thinner. Accordingly a current starts to flow and increases. When the film is perfectly removed, a current saturates. Namely, when a current saturates, purification is completed.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method and apparatus for detecting the degree of contamination or cleanliness inside a reactor of a plasma apparatus such as a thin film deposition apparatus and a thin film etching apparatus using plasma.

After performing thin film deposition or thin film etching using plasma in the manufacture of semiconductor devices, etc.
Thin films deposited on semiconductor device substrates and etching products from semiconductor device substrates also adhere to the electrodes and walls of plasma equipment, and gases generated from contamination inside these equipments and secondary deposits on the electrodes and walls during discharge. Due to the change in the amount of secondary electron emission, the reproducibility of deposition and etching deteriorates. To prevent this, conventionally, an inert gas such as argon or an active gas such as oxygen is introduced into the plasma device and discharged for a certain period of time to sputter and ash the deposits on the electrodes and wall soil to clean the inside of the device. I was doing it.

However, this method requires thin film deposition,
The degree of contamination on the electrodes, walls, etc. varies depending on the time and amount of etching, etc., so if the cleaning time is short relative to the degree of contamination, contamination may remain inside the device even after a certain period of cleaning. However, if the cleaning time is long relative to the degree of contamination, the throughput decreases and energy is wasted. In addition, conventionally, a probe was introduced into the discharge plasma,
There was a method to measure various plasma quantities such as plasma spatial potential distribution, ion density, electron density, and electron temperature, but this method did not reveal the degree of contamination or cleanliness inside the reactor of a plasma device.

The purpose of the present invention is not only to provide a simple method and device for use in a plasma device, but also to improve the above-mentioned drawbacks regarding the cleaning time of conventional methods for cleaning the inside of a reactor in a plasma device. It was made in For example, the present invention provides a method and device for detecting contamination level or cleanliness in which a detection unit is installed in a plasma device and the point in time when the current flowing into the detection unit starts to increase and reaches saturation is regarded as the end point of cleaning. This makes it possible to perform efficient cleaning, without reducing throughput or wasting energy, and with sufficient reproducibility. Further, in this invention, conversely, the degree of contamination can be recognized by observing the reduction in current.

Embodiments of the present invention will be described below with reference to the drawings. The first example is cleaning the inside of a plasma device after dry etching.
The explanation will be given based on FIG. 3 from the figure. Note that the contamination level inspection can be considered in reverse, so the explanation will be omitted below.

FIG. 1 shows an embodiment of the apparatus according to the present invention, in which the inner wall 2 of a dry etching apparatus 1 is coated with an insulating material 3 such as quartz, aluminum fH Teflon, etc., and the surface 4 is exposed inside the plasma apparatus. , a metal 6 such as tungsten or stainless steel is attached, and a voltage applying part 6 is attached to this. Current measurement section 7. Connect earth 8. 9 is an electrode.

FIG. 2 shows another embodiment of the invention, in which the electrode 9 of the dry etching device 1 is made of quartz as in the previous embodiment.

The surface 4 is coated with an insulator 3 such as alumina or Teflon.
Platinum exposed in a plasma device.

A metal 5 such as tungsten or stainless steel is attached to the voltage applying part 6. Current measurement section 7. Connect earth 8.

FIG. 3 shows the change over time of the current flowing from the discharge plasma into the detection section of the contamination degree/cleanliness detection device configured as described above. Oxygen plasma is used to clean the inside of the plasma device, and pressure is applied.・2 Torr.

The high frequency applied power was 0.5 W/j, the voltage applied to the detection part was -100V, and the size of the exposed part of the detection part was a diameter o-
It has a disc shape of s mw. As is clear from Figure 3, immediately after the start of cleaning (interval B in Figure 3), that is, immediately after the start of discharge, decomposition of Freon gas, etc., used in the dry etching performed before cleaning, is generated on the surface of the detection part. Current does not flow because there is a film of substances or etching reaction products attached, but as time passes, the oxygen plasma ashes or sputters the film, thins the film, and the current starts to flow. middle BO), saturates when those films are completely removed (point C). That is, the point C at which the current value is saturated in FIG. 3 is the end point of cleaning, and with this method, the end point of cleaning of the plasma apparatus can be detected with high accuracy and the cleaning can be completed.

In addition, the saturation current value at point C is always constant as long as the discharge conditions used for cleaning are constant, so it is not set at the end point C of cleaning, and is within the tolerance of the cleanliness inside the reactor of the plasma device. Depending on the situation, cleaning may be terminated at a point below the saturation current value, for example at the dot in FIG.

In this example, oxygen plasma was used for cleaning, but active gas such as Freon gas or nitrogen gas, or inert gas such as argon gas may also be used.
The applied voltage may be any condition as long as the plasma device used can stably discharge. In addition, in this example, the voltage applied to the detection part was set to 100V, but any voltage may be applied as long as it does not cause any abnormality in the discharge, and even if it is equal to the potential of the actual electrode or the potential of the inner wall of the plasma device, the cleanliness will be the same. It is possible to detect.

When the method according to the present invention was applied to detect the end point of cleaning of dry etching equipment after the dry etching process in the manufacture of semiconductor devices, the cleaning time was optimized according to the degree of contamination, and etching was completed without contamination after cleaning. The results showed that reproducibility was obtained, and since there was no need to clean too much beyond the degree of contamination, energy and time were not wasted, and throughput was increased.

In the above example, the detection of the cleanliness inside the plasma equipment after dry etching was taken as an example. It can also be fully applied to detecting cleanliness.

As explained above, the present invention can accurately detect the degree of contamination and cleanliness of various plasma devices, and can improve the reproducibility of plasma processes in the manufacture of semiconductor devices, for example.
This will greatly contribute to improving reliability and promoting automation of plasma equipment.

[Brief explanation of the drawing]

1 and 2 are schematic configuration diagrams of a plasma device equipped with a contamination degree and cleanliness detection device according to an embodiment of the present invention, and FIG.
The figure is a diagram showing temporal changes in the current flowing into the detection section of the contamination degree and cleanliness detection device. 1...Dry etching device, 2...
Inner wall, 3...Insulator, 4...Surface of detection part, 6...Metal of detection part, 6...Voltage application part, 7... . . . Current measurement unit, 9 . . . Electrode of dry etching device. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure 2 113 Figure 1 Child 1 Yoshikai (Gold.

Claims (1)

[Claims] (1) A method for detecting the degree of contamination or cleanliness in plasma processing, characterized by detecting the degree of contamination or cleanliness within the plasma apparatus based on the current value or voltage value flowing from the discharge plasma to the detection unit. . (2) The degree of contamination in plasma processing according to claim 1, characterized in that the point at which the current flowing from the discharge plasma to the detection section begins to increase and reaches saturation, or the point at which it reaches saturation, is regarded as the end point of cleaning. Cleanliness detection method. (3) It has a metallic detection part whose parts other than the exposed part are coated with an insulator, a voltage application part to the detection part, and a current measurement part of the detection part, and the exposed part of the detection part is connected to a plasma device. A contamination level or cleanliness detection device for plasma processing characterized by being exposed inside. (4) The contamination level or cleanliness detecting device for plasma processing according to claim 3, wherein the detecting section is attached to the inner wall of the plasma device. (6) A contamination level or cleanliness detecting device for plasma processing according to claim 3, wherein the detecting portion is attached to an electrode of a plasma device.