JPS62287079A - Plasma cvd apparatus - Google Patents

Abstract

PURPOSE:To enable the removal of useless films sticking to all the constituent parts in a vacuum vessel by placing an auxiliary electrode so as to easily generate low temp. plasma even at a position at which low temp. plasma is hardly generated by conventional plasma cleaning. CONSTITUTION:This plasma CVD apparatus is composed essentially of a vacuum vessel 41, an evacuating means 49, a pressure controlling means 51, a gas feeding means, a means 43 of holding a body to be processed, a main electrode 46, an auxiliary electrode 52, and a means 53 of supplying high frequency electric power to the electrode 52. When high frequency electric power is supplied to the main electrode 46, the electrode 46 generates low temp. plasma in the space in the vacuum vessel 41 including the body 42 to be processed in a prescribed pressure state. The auxiliary electrode 52 is placed at a proper position in the vessel 41 and removes a deposit sticking to the constituent parts in the vessel 41 by low temp. plasma.

Description

Detailed Description of the Invention 3. Detailed Description of the Invention Field of Industrial Application 2.
The present invention relates to a plasma CVD apparatus for forming a thin film on the surface of a sample, which is a workpiece, by a vapor deposition (vapor deposition) method.

In the conventional plasma CVD method, a sample is held in a vacuum container, and a compound gas containing the constituent elements of the thin film to be formed is supplied.
Exciting the compound gas by high frequency energy,
This is a method of forming (depositing) a thin film on a sample surface by placing the sample surface in a low-temperature plasma atmosphere.

This method utilizes the activity of low-temperature plasma, so
It is characterized in that thin films can be formed at low temperatures ranging from room temperature to about 40°C.

Issues in forming thin films by plasma CVD include control of the quality and thickness distribution of the formed thin film, and problems with film defects such as pinholes and particle adhesion. Another issue in terms of production is improving the deposition rate.

Therefore, it is necessary to uniformly test a high quality plasma CVD film.
3"'-. In order to form a film on the surface of a material, it is necessary to devise process conditions such as the distribution and stability of low-temperature plasma during thin film formation, sample heating distribution, and sample holding temperature.

An example of the above-mentioned conventional plasma vapor phase growth apparatus will be described below with reference to the drawings.

FIG. 2 shows a conventional plasma vapor phase growth apparatus.

In Figure 2, 1 is a vacuum container that can maintain a vacuum state, 2 is a sample on which a plasma CVD film is formed, and 3 is a sample 2.
and has an internal heater for heating sample 2.
4 is a heater mounted inside the sample stage 3, 5 is an AC power source for supplying AC power to the heater 4, and 6 is, for example, 50K) (supplied with high frequency power of z). 7 is a high frequency power source with a frequency of 50 KHz, 8 is a vacuum pump for evacuating the pressure inside the vacuum container 1 to a degree of vacuum below atmospheric pressure, 9 is a vacuum pump for vacuum container 1
A vacuum evacuation pipe 1Q airtightly connects the vacuum pump 80 and the vacuum pump 80, and the pipe 1Q changes the pressure inside the vacuum container 1 by varying the resistance inside the pipe.
That is, a valve valve 11 is a gas nozzle for introducing a compound gas into the vacuum vessel 1 via a gas flow rate control device.

The operation of the plasma vapor phase growth apparatus configured as described above will be explained below.

First, the inside of the vacuum container 1 is heated to 60mTor by the vacuum pump 8.
After evacuation to a vacuum level below
1 into the vacuum container 1 while being controlled by a flow rate controller. Furthermore, by operating the butterfly valve 1o, the pressure, which is the thin film forming condition, is adjusted to 100 to 40 o mTorr.
The inside of the vacuum container 1 is controlled to. Further, the sample 2 is heated and controlled by the sample stage 3 to a temperature of about 0.degree. C. by force. Next, the compound gas is excited by supplying high-frequency power with a frequency of 50 KHz to the electrode 6, and the surface of the sample 2 is exposed to the plasma atmosphere, thereby forming a plasma CVD film on the surface of the sample 2.

By the way, when forming a plasma CVD film on the surface of the sample 2, a similar film (ineffective film) is also formed on the electrode 6, sample stage 3, vacuum container 1, etc. 6' and other components inside the vacuum container 1. accumulate. That is, similar films accumulate on the components within the vacuum vessel 1. This similar film has relatively weak adhesion, and as the film thickness increases, flakes are generated within the vacuum vessel 1. As a result, a large amount of particles adhere to the surface of sample F42, causing film defects in the plasma CVD film formed on the surface of sample 2.

Therefore, it is necessary to periodically remove the ineffective film adhering to the components inside the vacuum vessel 1. A plasma cleaning method is used as a means for this purpose. This involves introducing halogen gas into the vacuum chamber 1 through the gas nozzle 11, maintaining it at a predetermined pressure, and then supplying high-frequency power to the electrode 6 to generate low-temperature plasma within the vacuum chamber 1. The activated species of this method dry-etch the ineffective film. For example, in the case of a plasma CVD apparatus that deposits a silicon nitride film on the surface of the sample 2, the halogen gas is a mixture of sulfur hexagonide (SF6), carbon tetrafluoride (OF4), and oxygen (O2). Gas is used.

6 Problems to be Solved by the Beno Invention However, the conventional configuration described above had the following problems. In other words, in the case of the plasma CVD apparatus shown in FIG. 2, high-activity low-temperature plasma is obtained in the space above the sample stage 3 at A part 9 in the figure, so plasma cleaning is good. Middle B club tsu''!
, Since low-temperature plasma is hardly generated in the space below the sample stage 3, it is difficult to remove an ineffective film. Therefore, it is necessary to stop the apparatus and mechanically remove those films using, for example, a plan, which deteriorates the workability of the plasma CVD apparatus.

As described above, in the conventional plasma CVD apparatus, there are parts in which it is extremely difficult to remove an ineffective film by plasma cleaning, and there is a problem in that the workability is deteriorated in terms of operation.

In view of the above-mentioned problems, the present invention has been developed using a plasma C that is capable of efficiently plasma cleaning an ineffective film attached to any part of the bottom part of the vacuum chamber 1 of a plasma CVD apparatus.
The purpose is to provide a VD device.

Means for Solving the Problems The present invention solves the problems in two parts: a vacuum container capable of maintaining a vacuum state, a vacuum evacuation means for creating a reduced pressure atmosphere inside the vacuum container, and a vacuum container. A pressure control means for controlling the pressure inside the vacuum container to a predetermined value, a gas supply means for introducing gas into the vacuum container, a workpiece holding means for holding the workpiece, and a , a main electrode that is supplied with high-frequency power and generates low-temperature plasma in a space containing at least the workpiece under a predetermined pressure state; a high-frequency power source that supplies high-frequency power to the main electrode; at least one auxiliary electrode positioned in the vacuum vessel for removal of deposits by means of a low-temperature plasma;
The device is characterized by comprising a high-frequency power supply means for supplying high-frequency power to the auxiliary electrode.

Function The present invention has a two-part structure, in which the main electrode is used to control the atmosphere in a vacuum container controlled according to the purpose of each work, when depositing a plasma CVD film separately and when performing normal plasma cleaning. By generating low-temperature plasma inside the
A plasma CVD film can be deposited on the sample surface on the workpiece holding means, and normal plasma cleaning can be performed.

On the other hand, auxiliary electrodes can be placed at appropriate locations within the vacuum vessel.
The main electrode is placed in a space below the workpiece holding means in the shredding vacuum container, which is a part where low-temperature plasma for cleaning is difficult to generate in normal plasma cleaning using the main electrode, and low-temperature plasma is generated in that part. , plasma cleaning can be performed.

EXAMPLE Hereinafter, a plasma CVD apparatus according to an example of the present invention will be described with reference to the drawings.

FIG. 1 shows a schematic cross-sectional view of a plasma vapor phase growth apparatus in a first embodiment of the present invention.

In FIG. 1, 41 is a vacuum container capable of maintaining a vacuum state, 42 is a sample as a workpiece on which a plasma CVD film is formed, and 43 is a container that holds the sample 42 and has a heating device inside. 44 is a heating device mounted inside the sample table 43, 45 is an AC power source, and 46 is a frequency of 50 KHz. a main electrode to which high-frequency power is supplied; 47 is a gas flow rate control device;
48 is a high frequency power source with a frequency of 50 KHz; 49 is a vacuum pump as a vacuum evacuation means for reducing the pressure inside the vacuum container 41 to a degree of vacuum below atmospheric pressure; and 50 is a vacuum pump for airtightly connecting the vacuum container 41 and the vacuum pump 49. 61 is a pressure control device for controlling the pressure inside the vacuum container 41; 52 is an auxiliary electrode to which high-frequency power is supplied; 41 is installed at the inner bottom. Reference numeral 53 denotes an auxiliary electrode, and a power source that supplies high frequency power to 52.

The operation of the plasma CVD apparatus configured as described above will be explained below with reference to FIG.

Without a trench, the inside of the vacuum container 41 is pumped by a vacuum pump 49 for 30 minutes.
After evacuation with a vacuum change of less than mTorr, test sample 42
10″-″ compound gas containing the compositional system of the thin film to be formed on the surface, i.e., monosilane (S I H4)
, ammonia (NH3), and W element (N2) at 13SCCM, 31SCCM, and 142SCCM, respectively.
At a gas flow rate of , the gas flow rate controller 47
The pressure inside the vacuum vessel 41 is maintained at 260 mTorr by operating the pressure control device 51.

Further, the sample 42 is heated and controlled to a temperature of 300° C. by the sample stage 43. Next, low-temperature plasma is generated in the space containing the sample 42 by supplying high-frequency power with a frequency of 50 KHz from the high-frequency power source 48 to the main electrode 46 . As a result, the refractive index on the sample 42 was 1.998±0.
02, a silicon nitride film with a film thickness distribution of ±3tI) could be formed.

Next, the operation when performing plasma cleaning will be explained.

First, after taking out the sample 42 from inside the vacuum container 41, the inside of the vacuum container 41 is introduced into the vacuum container 41 by the vacuum pump 49, and the volume control device 47 is introduced into the vacuum container 41. 3 by operating the pressure control device 51 to control the pressure.
Hold at 00 mTorr r. Next, low-temperature plasma is generated by supplying high-frequency power with a frequency of 50 KHzO from the high-frequency power source 48 to the main electrode 46 . In this first step of normal plasma cleaning, the film deposited on the components inside the vacuum vessel 41 located in the space above the sample stage 43 in section A indicated by diagonal lines in FIG. 1 is removed.

Next, the output of the high frequency power source 48 is stopped, and then high frequency power with a frequency of 50 KHz is applied to the auxiliary electrode 52 by the power source 5.
3. Supply low temperature plasma to generate low temperature plasma.

In this second step of plasma cleaning, the film deposited on the components inside the vacuum vessel 41 located in a portion B indicated by crossed diagonal lines in FIG. 1, that is, in the space below the sample stage 43, is removed.

As described above, according to this embodiment, the auxiliary electrode 52 is arranged in the vacuum chamber 41 of the plasma CVD apparatus in a part where low-temperature plasma is difficult to generate in normal plasma cleaning, and high-frequency power is applied to the auxiliary electrode 62 from the power source 63. By supplying low-temperature plasma to the space including the auxiliary electrode 62, it is possible to efficiently plasma-clean ineffective films attached to components in parts of the vacuum container 41 that are difficult to clean with normal plasma cleaning. can do.

In this embodiment, the power source 53 is used to supply high frequency power to the auxiliary electrode 62, but high frequency power may be applied from the high frequency power source 48, and the first plasma cleaning and the second plasma cleaning may be performed. You can do them at the same time. In addition, the frequency of high frequency power is 50 KHz
However, it was 380KHz.

Similar results were obtained at frequencies such as 13MHz and 56MHz, and the effect of the present invention is not dependent on frequency.

Effects of the Invention According to the present invention, since it has the above-described structure and operation, the auxiliary electrode allows low-temperature plasma 13B/plasma to be applied to areas in the vacuum chamber of a plasma CVD apparatus where low-temperature plasma is difficult to generate with normal plasma cleaning. This makes it possible to efficiently, easily and thoroughly remove ineffective films attached to any component within the vacuum vessel by plasma cleaning.

[Brief explanation of drawings]

FIG. 1 is a schematic sectional view of a plasma CVD apparatus according to an embodiment of the present invention, and FIG. 2 is a schematic sectional view of a conventional plasma CVD apparatus. 41... Vacuum container, 42... Sample, 4
3... Sample stand, 44... Heating device, 4
6...--AC power supply, 46... Main electrode, 4
7...Gas flow rate control device, 48...High frequency power supply, 49.A...Vacuum pump, 60...
Pipe, 61... Pressure control device, 62...
...Auxiliary electrode, 53...Power supply.

Claims (1)

[Claims] A vacuum container capable of maintaining a vacuum state, a vacuum evacuation means for creating a reduced pressure atmosphere in the vacuum container, a pressure control means for bringing the pressure inside the vacuum container to a predetermined value, and a gas injecting into the vacuum container. a gas supply means for introducing the workpiece; a workpiece holding means for holding the workpiece; a main electrode for generating electricity, a high-frequency power source for supplying high-frequency power to the main electrode, and at least one auxiliary electrode provided at an appropriate location within the vacuum vessel for removing deposits attached to components within the vacuum vessel by low-temperature plasma. A plasma CVD apparatus comprising: and high-frequency power supply means for supplying high-frequency power to an auxiliary electrode.