JPS62287078A - 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 electrically floating a sample stand 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, an electrode 46 and a means 43 of holding a body 42 to be processed. When high frequency electric power is supplied to the electrode 46, the electrode 46 generates low temp. plasma in the space in the vacuum vessel 41 including the body 42 to be processed. The holding means 43 floats electrically and can be earthed or high frequency electric power can be supplied to the means 43.

Description

Detailed Description of the Invention 3. Detailed Description of the Invention Field of Industrial Application The present invention is directed to plasma CVD (Chetnical
Using the VaporDeposition method, plasma C is used to form a thin film on the surface of the sample, which is the workpiece.
This relates to a VD device with two vanes.

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 4°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, in order to uniformly form a high-quality plasma CVD film on the sample surface, it is necessary to devise process conditions such as the distribution and stability of the low-temperature plasma during thin film formation, the sample heating distribution, and the sample holding temperature. It's peaceful.

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 Fig. 2, 1 is a vacuum container capable of maintaining 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 supplied with high frequency power of, for example, 50k) h. 7 is a high frequency power source with a frequency of 50kHz,
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 pipe for evacuation that airtightly connects the vacuum container 1 and the vacuum pump 8; 10 is a vacuum container 1 is a butterfly valve that controls the pressure inside 1 by making the internal resistance of the pipe variable, that is, the effective pumping speed of the vacuum pump 8 variable; 11 is a gas nozzle for introducing compound gas into the vacuum container 1 via a gas flow rate controller; It is.

The operation of the plasma vapor deposition apparatus configured as described above will be described below.

First, the inside of the vacuum container 1 is heated to 50 m T by the vacuum pump 8.
After evacuation to a degree of vacuum below o r r, a compound gas containing the constituent elements of the thin film to be formed on the surface of the sample 2 is pumped into the vacuum vessel 1 through the gas nozzle 11 while being controlled by the flow rate controller.
to be introduced within. Furthermore, operate the butterfly valve 10,
The pressure that is the thin film formation condition is 100 to 400 mT.
The inside of the vacuum container 1 is controlled to orr. Further, the sample 2 is heated and controlled to a temperature of about 300° C. by the sample stage 3. next,
A plasma CVD film is formed on the surface of the sample 2 by exciting the compound gas and exposing the surface of the sample 2 to the plasma atmosphere by supplying high frequency power with a frequency of 50 to the electrode 6.

By the way, when forming a plasma CVD film on the surface of the sample 2, the electrode 6, the sample stage 3, the vacuum vessel 1, etc.
A similar film (ineffective film) is also deposited on internal components. 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 adhered to the surface of sample 2, and a plasma CV formed on the surface of sample 2.
D causes film defects in the film.

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 device that deposits a silicon nitride film on the surface of the sample 2, the halogen gas may be sulfur hexafluoride (SF6) or a mixed gas of carbon tetrafluoride (CF4) and oxygen (02). used.

Problems to be Solved by the Invention However, the conventional configuration described above has the following problems. In the case of the 6-page plasma CVD apparatus shown in Fig. 2, highly active low-temperature plasma is obtained in the area A in the figure, that is, the space above the sample stage 3, so plasma cleaning is good. For example, in the space below the sample stage 3 in section B in the figure, low-temperature plasma is hardly generated, so it is difficult to remove an ineffective film. Therefore, it is necessary to stop the equipment and remove those films mechanically, for example with a brush.
Deteriorates the workability of the equipment.

As described above, the conventional plasma CVD apparatus has a problem in that there are parts where ineffective films cannot be removed by plasma cleaning, which deteriorates the workability.

SUMMARY OF THE INVENTION In view of the above-mentioned problems, an object of the present invention is to provide a plasma CVD apparatus capable of efficiently plasma cleaning an ineffective film attached to any part of a component inside a vacuum chamber 1 of a plasma CVD apparatus. It is something.

Means for Solving the Problems In order to solve the above-mentioned problems, the present invention provides a vacuum container capable of maintaining a vacuum state 7, and a vacuum evacuation means for creating a reduced pressure atmosphere inside the vacuum container. , a pressure control means for bringing the pressure in the vacuum container to a predetermined value, a gas supply means for introducing gas into the vacuum container, and a pressure control means located within the vacuum container, and supplied with high frequency power to maintain the predetermined pressure state. an electrode that generates low-temperature plasma in at least a space containing the workpiece in the vacuum container; and an electrode that is located in the vacuum container and is electrically floating and can be grounded or supplied with high-frequency power;
The present invention is characterized in that it also includes a workpiece holding means capable of holding the workpiece.

Function The present invention has the above-described configuration, in which the workpiece holding means is electrically floating and can be selectively grounded to supply high-frequency power. Therefore, when depositing a plasma CVD film on a sample or during normal plasma cleaning, by grounding the workpiece holding means, it is possible to prevent A low-temperature plasma is generated in the upper space of the workpiece holding means to deposit a plasma CVD film on the sample surface on the workpiece holding means, and also for normal plasma cleaning, especially on the workpiece holding means in the vacuum chamber. Plasma cleaning can be performed in the space. When performing plasma cleaning on the lower part of the workpiece holding means, high-frequency power is applied to the workpiece holding means in an atmosphere within the vacuum container that is controlled according to the work, thereby cleaning the inside of the vacuum container. Plasma cleaning can be performed in the space below the workpiece holding means in the vacuum container by generating low temperature plasma in the space below the workpiece holding means.

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, numeral 41 is a vacuum container capable of maintaining a vacuum state, and numeral 9 is a vacuum container in which a plasma CVD film is formed.

43 is a sample stand as an electrically floating workpiece holding means that holds the sample 42 and has a heating device inside and can heat the sample 42; 44; 45 is a heating device mounted inside the sample stage 43;
46 is an AC power source, 46 is an electrode to which a high frequency wave with a frequency of 601 is supplied, 47 is a gas flow rate control device, 48 is a high frequency power source with a frequency of 50 tunes, and 49 is a device for reducing the pressure inside the vacuum container 41 to a degree of vacuum below atmospheric pressure. 50 is a vacuum evacuation pipe that airtightly connects the vacuum container 41 and the vacuum pump 49; 61 is a pressure control device for controlling the pressure in the vacuum container 41; 62 is a vacuum pump as an evacuation means; , sample stage 4
A power source 53 for supplying high frequency power to the sample stage 3 is a connector that can arbitrarily select and connect the electrically floating sample stage 43 to earth ground or the power source 62.

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

First, the vacuum pump 49 pumps the inside of the vacuum container 41 for 30 minutes.
After vacuum evacuation with a vacuum change of less than mTorr, a compound gas containing the constituent elements of the thin film to be formed on the surface of the sample 42, namely, monosilane (S NH4), 1 alumonia (NH3), and nitrogen (N2), was added. The mixed gases are introduced into the vacuum container 41 from the gas flow rate controller 47 at gas flow rates of 1 sSCCM, 31 SCCM, and 142 SCCM, respectively, and the pressure inside the vacuum container 41 is controlled by the pressure controller 5.
1 and maintain it at 260 mTorr.

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 at a frequency of 50 to the high-frequency power supply 48 to the electrode 46 . here,
The sample stage 43 is grounded. As a result, it was possible to form a silicon nitride film on the sample 42 with a refractive index of 1.998±0.02 and a thickness distribution of ±3.

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 evacuated to a vacuum level of 11 vanes □↑ 3 omTorr or less using the vacuum pump 49, and then sulfur hexafluoride (SF6) gas is pumped into the vacuum container 41. A gas flow rate of 200 SCCM is introduced into the vacuum container 41 from the gas flow rate control device 47,
In addition, the pressure inside the vacuum container 41 is maintained at 30 m Torr by operating the pressure control device 51. Next 3
A low-temperature plasma is generated by supplying high-frequency power with a frequency of 50 klk from a high-frequency power source 48 to the pole 46 . Here, the sample stage 43 is grounded. This first
In the plasma cleaning step, the film deposited on the components inside the vacuum vessel 41 located at a portion A indicated by the oblique line in FIG. 1 is removed.

Next, the output of the high-frequency power source 48 is stopped, and then the grounded sample stage 43 is floated in potential, and high-frequency power with a frequency of 50 tunes is supplied from the power source 52 to generate low-temperature plasma. In this second step of plasma cleaning, the film deposited on the components inside the vacuum vessel 41 located at a portion B indicated by cross hatching in FIG. 1 is removed.

As described above, according to this embodiment, the sample stage 43 floats in potential, and during normal plasma cleaning,
A low-temperature plasma is generated by grounding the sample stage 43 and supplying high-frequency power to the electrode 46, and then,
By supplying high-frequency power from the power source 52 to the sample stage 43, low-temperature plasma can be easily generated even in the lower part of the sample stage 43, that is, the part where low-temperature plasma is difficult to generate. It is possible to efficiently plasma clean the ineffective film attached to the surface.

In this embodiment, the power source 52 is provided to supply high frequency power to the sample stage 43, but the high frequency power source 48 may also be used. Further, although the frequency of the high-frequency power was set to 50kl (Z), similar effects were obtained for frequencies such as 380 songs and 13.561%, and the effects of the present invention are not dependent on frequency.

Effects of the Invention According to the present invention, the sample stage is electrically floating, and when performing normal plasma cleaning, when the sample stage is grounded and high frequency power is supplied to the electrodes, low temperature plasma is generated by the 13 vanes. Then, by supplying high-frequency power to the sample stage from a power source, low-temperature plasma can be easily generated even in the lower part of the sample stage, that is, in the area where low-temperature plasma is difficult to generate with the above-mentioned normal plasma cleaning. Therefore, an ineffective film attached to any part of the components inside the vacuum container can be efficiently and easily removed 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, 43
...Sample stage, 44...Heating device, 45
... AC power supply, 46 ... Electrode, 47.
...Gas flow control device, 4th...High frequency power supply, 49...Vacuum pump, 50...
Pipe, 61... Pressure control device, 62...
...Power supply, 53...Connector.

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 gas, an electrode located in the vacuum container and supplied with high-frequency power to generate low-temperature plasma in a space containing at least the workpiece in the vacuum container under a predetermined pressure state, and an electrode located in the vacuum container. 1. A plasma CVD apparatus that is electrically floating, capable of supplying earth grounding or high-frequency power, and comprising a workpiece holding means for holding a workpiece.