JPH03193131A - Vacuum treatment apparatus having ionizing mechanism - Google Patents

Abstract

PURPOSE:To reduce the amount of the dust flying up within a vacuum chamber bonded to the surface of a material to be treated when substituent gas or vacuum releasing gas is introduced by providing a discharge chamber in a gas introducing apparatus and ionizing non-combustible gas in the discharge chamber. CONSTITUTION:Non-combustible gas is used as substituent gas or vacuum releasing gas. A gas introducing apparatus 5, the vacuum chamber 15 communicating with the introducing apparatus 5 through a pressure reducing valve 13 and the exhaust apparatus 18 connected to the vacuum chamber 15 are provided. A discharge chamber 8 is provided in the introducing apparatus 5 and the non- combustible gas is ionized in the discharge chamber 8. As a result, the adhesion amount of the dust flying up in the vacuum chamber when the substituent gas or vacuum releasing gas is introduced to the surface of a material to be treated is reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to processing performed in a vacuum environment, film formation heat treatment,
A work environment where extremely small dust of submicron to several micron size that adheres to the object to be processed during loading/unloading, processing, etc. in processes such as crystal growth must be suppressed to 1/cm2 or less. , for example, relates to a vacuum processing apparatus used in a semiconductor manufacturing environment.

(Prior art) In this type of conventional equipment, when replacing the gas in the vacuum chamber,
Alternatively, when the vacuum release gas is introduced into the vacuum chamber, turbulent flow occurs in the vacuum chamber, causing dust that has accumulated or adhered to the vacuum chamber to fly up, and some of the dust to be attached to the object to be processed. There was a drawback.

To reduce the amount of dust adhering to the object to be processed, ■ Install the object to be processed with the front side facing downward, ■ Reduce the amount of dust in the vacuum system by regularly polishing and cleaning the vacuum chamber, and ■ Save time. Methods have been taken to suppress the occurrence of turbulent flow by replacing the gas by applying pressure or releasing the vacuum.

In an example of the inventors' experience in semiconductor manufacturing, when a St wafer is used as an object to be processed and a metal film is deposited on the wafer, a gas replacement rate of 10 By reducing the speed from liter/min to 0.1 liter/min, dust attached to the wafer can be reduced to 100/cm.
It was possible to reduce it from m2 to 1/cm2. However, in order to further reduce the dust l- However, it would be difficult to reduce the amount of dust as it would only reduce the processing capacity.

(Problems to be Solved by the Invention) The present invention was proposed in order to improve the above-mentioned drawbacks, and its purpose is to cover the dust that flies up inside the vacuum chamber when introducing replacement gas or introducing vacuum release gas. An object of the present invention is to provide a vacuum processing apparatus in which the amount of adhesion to the surface of a processing object is reduced.

(Means for Solving the Problems) In order to achieve the above object, the present invention uses a non-flammable gas as a replacement gas or a vacuum release gas, and includes the above-mentioned gas introduction device and the above-mentioned gas introduction device. a vacuum chamber connected via a pressure reducing valve; and an exhaust device connected to the vacuum chamber; a discharge chamber is provided in the gas introduction device; The gist of the invention is a vacuum processing apparatus having an ionization mechanism that ionizes gas.

(Function) In the present invention, a non-flammable gas such as a replacement gas or air to be sent into the vacuum chamber is sent into the discharge chamber in advance, and the pressure is approximately atmospheric pressure ~10~'
By causing corona discharge or self-discharge under the pressure of Torr, ionizing the gases, and introducing the gases into the vacuum chamber, the gases are blown onto the wafer surface and onto the surface of the object to be processed. It has the effect of electrically neutralizing the electrostatically attached dust, thereby reducing the adhesion of dust on the surface of the object to be treated.

Therefore, the present invention differs greatly from conventional vacuum devices that use electrically neutral gas in that it uses ionized gas.

(Example) Next, an example of the present invention will be described. It should be noted that the embodiments are merely illustrative, and it goes without saying that various changes and improvements can be made without departing from the spirit of the present invention.

1(a)-(C) illustrate the principle of the present invention.

In the figure, 1 is a flow of ionized gas, 2 is an object to be processed, 3 is dust attached to the surface of the object to be processed, and 4 is dust blown off by the ionized gas. Here, the mark indicates a state of being charged with a positive potential, the - mark indicates a state of being charged with a negative potential, and N indicates a state of being electrically neutral.

For convenience of explanation, we will use an example where the object to be processed is charged negatively and the dust is charged positively, but if the object is charged oppositely, that is, the object to be processed is charged positively and the dust is charged negatively. Since the situation is considered to be the same even if

In FIG. 1(a), when the ionized gas 1 is blown onto the object 2 to be treated and the dust 3 electrostatically attached, the negatively ionized gas molecules collide with the dust. As shown in Figure (b), the dust loses potential.

For this reason, the electrostatic bonding force between the object to be processed and the dust a is weakened. Figure 1 (C)
As shown, the dust is blown away.

By the way, when gas is ionized in a vacuum atmosphere, if the pressure of the gas is set to a high vacuum of 10-' Torr or less, the mean free path is approximately on the order of meters, which is about the same as the distance between the electrodes. For this reason, unlike a low-vacuum discharge of 10-'Torr or more, almost no ionization of gas molecules occurs (Discharge Handbook, p. 21). Institute of Electrical Engineers of Japan). Therefore, an important point of the present invention is to perform the discharge in a low vacuum where the gas pressure is 10-'Torr or more.

FIG. 2 shows a conceptual diagram of the device according to the invention.

In the figure, 5 is an ionized gas introducing device, and inside this is a vacuum control device 6, a discharge power source 7, a discharge chamber 8, and a discharge chamber 9.
discharge device, 10 combustible gas detection devices, 1) vacuum gauge (A), 12 pressure reducing valves (A), 13 pressure reducing valves (B)
, 14 exhaust devices (A) are housed, and 16 vacuum gauges (B) and 17 pressure reducing valves (C) are connected to the vacuum chamber ]5, and 18 is an exhaust device that accommodates the pressure reducing valve ( C) connected to 17.

Here, the ionized gas introducing device 5 is a pressure reducing valve (B) 13.
It is connected to the vacuum chamber 15 via. Moreover, the pressure in this vacuum chamber 15 is controlled by an exhaust device (B) via a pressure reducing valve (C) 17.
) 18 and monitored by a vacuum gauge (B) 16.

Discharge power supply7. Flammable gas detection device 10. Vacuum gauge (A)
The data of LL and vacuum gauge (B) 16 are sent to vacuum control device 6, and pressure reducing valve (A) 12. Pressure reducing valve (B) 13, exhaust device (A) 14. The exhaust devices (B) 18 are each managed by a vacuum control device 6.

In the case of a general vacuum device, gas system piping is composed of a plurality of replacement gas system piping and one or more vacuum release system piping. When the present invention is introduced into such an apparatus, one ionized gas introduction device is installed for each gas system.

However, it is also possible to provide the vacuum control device with a multi-channel function and manage multiple systems with one vacuum control device. Incidentally, stable discharge accompanied by an ionization phenomenon is known as corona discharge in an uneven electric field and self-discharge. The present invention is applicable to both types of discharge. Since the operating principle remains the same, we will explain this using corona discharge as an example.

Since corona discharge has a stronger ionizing effect on gas, it has the advantage of being more efficient in removing the charged dust a.

On the other hand, in the case of self-discharge, the discharge power source 7 can be omitted, and control can be simplified.

Among the series of operations, the explanation will be limited to operations related to the present invention, that is, operations during gas introduction. For other operations, pressure reducing valve (A) 12. The pressure reducing valve (B) 13 is closed,
Since the operation is the same as that of a normal vacuum device, it will be omitted.

In addition, as mentioned earlier, when fishing on a boat, multiple pipes are connected to the vacuum device on the stand for replacing gases, releasing the vacuum, etc., and an ionized gas introduction device is connected to each pipe. Therefore, multiple units are required, but to avoid duplication of explanation, we have chosen one unit as a representative.

The degree of vacuum in the vacuum chamber 15 when introducing gas is usually 10-'Tor.
Since the vacuum is maintained at a high vacuum below r, it is difficult to directly ionize the replacement gas etc. by electric discharge. For this reason, vacuum chamber 1
A discharge chamber 8 was provided at the front stage of the discharge chamber 5, and a vacuum control device 6 was provided for controlling the degree of vacuum in the discharge chamber.

The degree of vacuum in the discharge chamber 8 and vacuum chamber 15 can be determined using a vacuum gauge (
A) 1). It is monitored by the vacuum gauge (B) 16, and the pressure reducing valve (A) 12. Pressure reducing valve (B) 13° controls exhaust system W14. When flammable gas enters the vacuum system, the flammable gas detection device 1o is activated immediately to stop the discharge.

In this way, ■ When the degree of vacuum in the vacuum chamber 15 is a high vacuum of 10-' Torr or less, the degree of vacuum in the discharge chamber is approximately 10-'Torr; In a vacuum, the degree of vacuum in the discharge chamber is maintained at the same level as the degree of vacuum in the vacuum chamber, but at a higher pressure than that in the vacuum chamber, and the discharge power source 7 is activated to ionize the gas in the discharge chamber. The gas is supplied to the vacuum chamber 15 via the pressure reducing valve (B) 13.

FIG. 3 shows the relationship between the degree of vacuum in the discharge chamber and the degree of vacuum in the vacuum chamber.

FIG. 4 shows an example of a corona discharge electrode installed in the discharge chamber 8 (FIG. 1), which is an example of a concentric cylindrical electrode. Comparing the amount of dust attached to the surface of the object to be treated according to this example and the amount of dust attached according to the conventional technology, the present invention 0.01 to 0.05/cmz Conventional example
A result of 1 to 3/cm2 was obtained. Here, the object to be processed is Si for tC production.
A wafer was used, and the duration of blowing the gas onto the object to be processed was 20 seconds. According to the present invention, the amount of dust adhering to the object to be treated can be reduced to about 1/100.

FIG. 5 is an example of a corona discharge electrode installed in the discharge chamber, and is an example of a needle-to-plate electrode.

FIG. 6 is an example of a corona discharge electrode installed in the discharge chamber, and is an example of a needle-to-needle electrode.

(Effects of the Invention) As mentioned above, according to the present invention, a non-flammable gas is used as the replacement gas or the vacuum release gas, and the above-mentioned gas introduction device, the gas introduction device, and the pressure reducing valve are provided. and an exhaust device connected to the vacuum chamber, a discharge chamber is provided in the gas introduction device, and the non-flammable gas is ionized by the discharge chamber. This has the effect of significantly reducing dust adhering to the object to be processed. Furthermore, since the discharge chamber is independent of the processing contents of the vacuum chamber, and the present invention can be widely applied to non-flammable gases, the present invention can be applied to various vacuum processing apparatuses, such as ■vacuum annealing equipment, bake ovens, etc.■vacuum Film deposition equipment such as sputtering equipment, vacuum thin deposition equipment, chemical vapor deposition equipment, etc. ■ Processing equipment such as reactive ion etching equipment, milling equipment, etc. ■ Ion implantation equipment, etc. ■ Molecular beam crystal growth equipment, vapor phase growth equipment, crystal growth equipment such as liquid crystal growth equipment ■ Ashing equipment, etc. ■ Plasma surface modification equipment, etc. 1 ■ Application to replacement gas in glove boxes, various vacuum storage devices, etc. ■ Widely used in other vacuum processing equipment It is applicable.

[Brief explanation of drawings]

Figures 1 (a) to (C) are diagrams showing the principle of the present invention, Figure 2 is a conceptual diagram of the device according to the present invention, and Figure 3 is a diagram showing the relationship between the degree of vacuum in the discharge chamber and the degree of vacuum in the vacuum chamber. Figure 4 is an example of a corona discharge electrode installed inside the discharge chamber, and is an example of a concentric cylindrical electrode, and Figure 5 is an example of a corona discharge electrode installed inside the discharge chamber, which is a needle-to-plane electrode. For example, FIG. 6 shows an example of a needle-to-needle electrode in an embodiment of a corona discharge electrode installed in a discharge chamber. 1...Flow of ionized gas, 2...Object to be treated 3...Dusts attached to the surface of the object to be treated 4...Dusts blown away by gas 5...Introduction of ionized gas Device 6... Vacuum control device 7... Power source for discharge 2 8 ・ ・ 10 ・ 1) ・ 12 ・ ・ 13 ・ ・ I4 ・ 15 ・ ・ 16 ・ 17 ・ 1 day・Discharge chamber discharge device・Flammable gas detection device ・Vacuum gauge A ・Pressure reducing valve A Pressure reducing valve B ・Exhaust device A ・Vacuum chamber ・Vacuum gauge B ・Pressure reducing valve C ・Exhaust device B 3

Claims (2)

[Claims] (1) A non-flammable gas is used as the replacement gas or the vacuum release gas, and the gas introduction device, the vacuum chamber connected to the gas introduction device via a pressure reducing valve, and the vacuum chamber A vacuum processing apparatus having an ionization mechanism, comprising: an exhaust device connected to the gas introduction device; a discharge chamber is provided in the gas introduction device; and the non-flammable gas is ionized by the discharge chamber. (2) Make the gas pressure of the introduction device higher than the gas pressure of the vacuum chamber,
2. A vacuum processing apparatus having an ionization mechanism according to claim 1, wherein the non-flammable gas is ionized by corona discharge or self-discharge while maintaining the pressure between approximately atmospheric pressure and 10^-^4 Torr.