JPS63297568A - Plasma CVD equipment - Google Patents

Abstract

PURPOSE:To effectively remove sticking matter in a chamber by means of plasma cleaning, by making a ground shield capable of being isolated from a ground and also by providing a means of switching the connection of a high- frequency electric power source from a CVD electrode to the ground shield. CONSTITUTION:A ground shield 4 is fitted slidably between a CVD electrode 3 and a guide cylinder 11, while holding insulating materials 5a, 5b in the inside and outside peripheral parts between, respectively. At the time of cleaning, the ground shield 4 is set in a lifted position and held in an state isolated from the ground 7, and an etching gas is introduced into a chamber 1. A switch 13 is shifted from a terminal 12a of the electrode 3 to a terminal 12b of the ground shield 4, and high frequency is impressed on the ground shield 4. The ground shield 4 acts as electrode for plasma cleaning, and produces plasma Pb in the spaces between the inner wall a and bottom 1b, opposite to the ground shield 4, of the chamber and the ground shield 4. By this method, the sticking matter adhering to the internal surface of the chamber 1 and the external surface of the ground shield 4 can be effectively removed by means of etching.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is directed to a counter-electrode type plasma CVD device in which the earth shield can also be used as a plasma cleaning electrode.
It is related to the device.

[Prior Art] As shown in FIG. 3, a facing electrode type plasma CVD apparatus, typically a parallel plate type, is constructed by arranging a substrate 2 and an electrode 3 facing each other in a chamber 1. In many cases, an earth shield 4 is disposed on the back surface of the electrode 3 to shield the electrode 3. This earth shield 4 is insulated from the electrode 3 with an insulating material 5 in between, and is securely connected to the earth 7 through the connector part 6, preventing discharge between the electrode 3 and the chamber 1, and directing the plasma Pa to the substrate. It plays the role of confining between the electrodes (in FIG. 3, 8 indicates a heater installed on the back surface of the substrate, and 9 indicates an RF power source that applies high frequency to the electrodes 3 via the matching box 10).

However, even when the above-mentioned earth shield 4 is provided, it is unavoidable that some plasma particles will wrap around, adhere to, and accumulate on the inner surface of the chamber 1 during film formation, and therefore Deposits (e.g. a-8i J
Ppoly-8i, etc.) is required.

On the other hand, plasma cleaning using etching is known as an effective and simple means for cleaning the inside of the chamber 1. That is, in this method, an etching gas such as CF4, NF3, etc. is introduced into the chamber 1, plasma discharge is generated between the electrode 3 and the chamber 1, etc., and the deposits are removed by etching.

[Problems to be Solved by the Invention] However, in the case where the earth shield 4 is disposed on the back of the electrode, the plasma generation area at that time is also covered by the shield 4.
Places where it is difficult for plasma to get around because of the shielding of
That is, the deposits that have adhered or accumulated on the chamber inner wall 1a, bottom 1b, etc. on the back side of the shield 4 are not easily removed.

Therefore, deposits that have adhered to places where the etching effect is difficult to spread can be removed by first releasing the inside of the chamber 1 to the atmosphere and then removing the deposits from the inner wall 1.
It is necessary to carry out separate cleaning work, such as physically polishing parts such as a, or removing and pickling parts.

However, if such a purifying means is adopted, not only is the cleaning work time-consuming, but also the inside of the chamber 1 must be exposed to the atmosphere each time, resulting in a decrease in the operating efficiency of the apparatus.

In order to solve these problems, the present invention provides an improved plasma CVD apparatus that can thoroughly remove deposits deposited inside the chamber by plasma cleaning without returning the inside of the chamber to the atmosphere. be.

[Means for Solving the Problems] The means taken by the present invention to achieve the above-mentioned object is that in an opposed electrode type plasma CVD apparatus having an earth shield, the earth shield is provided so as to be insulated from the earth, and the earth shield is provided so as to be insulated from the earth. The present invention is characterized in that a power source is connected to and connected to the earth shield and the electrode in a switchable manner.

[Function] With this configuration, when performing plasma cleaning inside the chamber, it is sufficient to insulate the earth shield from the earth and switch the connection of the high frequency power source from the CVD electrode to the earth shield. . Then, the earth shield to which the high frequency is applied acts as a plasma cleaning electrode, and discharge occurs between the shield and the inner surface of the chamber facing the chamber, generating plasma.

In this way, in this device, by using the ground shield as a cleaning electrode, it is possible to greatly change the plasma generation area in the chamber between CVD and cleaning (etching). Deposits attached to the inner wall or bottom of the chamber can be effectively removed by etching.

[Example code] Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

1 and 2 show an outline of the parallel plate type plasma CVD apparatus according to the present invention in comparison with the conventional example shown in FIG. 3. The figure shows the cleaning condition. Here, the reference numerals for each part related to the basic configuration of the device are used in common with those of the conventional example. That is, 1 is a chamber, 2 is a substrate, 3 is an electrode (for CVD), 4 is an earth shield, 7 is a ground, 8 is a substrate heater, 9 is an RF (high frequency) power source, and 10 is a matching box. Note that the electrode 3 can have various structures and forms, such as one that blows out gas from inside itself.

To explain the structure of the modified main parts of this device, first, the earth shield 4 is provided so as to be switchable from a securely connected state to the ground 7 to a securely insulated state from the ground 7. In order to enable such insulation from the earth 7, the earth shield 4 is provided as follows.

That is, a cylindrical earth shield 4 arranged around the electrode 3 so as to shield the back side has an insulating material 5 on the inner periphery.
A is slidably fitted between the electrode 3 and a guide cylinder 11 protruding from the bottom of the chamber 1 with an insulating material 5b sandwiched between the outer periphery, and is raised and lowered at a predetermined stroke from the atmosphere side toward the inside of the chamber 1. Possibly installed. An annular earth contact 6a having a cross-sectional shape is protruded from the outer periphery of the middle part of the chamber 1, while a ground 7 is connected to the chamber bottom 1b at a position facing the outer periphery of the earth contact 6a. A ground contact 6b is installed. Thus, when the earth shield 4 is in its lowered position, both contacts 6a and 6b are in close contact with each other, as shown in FIG. 1, and the earth shield 4 is maintained in a secure connection with the earth 7. . On the other hand, when the earth shield 4 is in its raised position, the contact 6a floats to a position completely separated from the contact 6b, as shown in FIG. 2, and is maintained in a securely insulated state from the earth 7. become.

Furthermore, the RF power source 9 that supplies power to the electrode 3 via the matching box 10 can be switched between the two so that it can be switched to the electrode 3 and apply high frequency to the earth shield 4 as needed. It is provided. That is,
Power supply terminals 12a and 12b are provided on the electrode 3 and the protruding end of the earth shield 4 on the atmosphere side, respectively, to which the output terminal 13 of the matching box 10 is selectively connected via a switch 14.

The plasma CVD apparatus configured as described above executes the formation of a thin film on the substrate 2 and the cleaning of the inside of the chamber 1 under the following operations.

First, during the CVD shown in Figure 1, the earth shield 4
A high frequency is applied to the electrode 3 while the electrodes 3 are securely grounded, and plasma Pa is generated in a confined area between the electrode 3 and the opposing substrate 2, and the substrates 2-1 . A film will form on the surface.

Next, during the cleaning shown in FIG. 2, the earth shield 4 is set in the raised position in the chamber 1 and the earth
At the same time, the above-mentioned etching gas is introduced into the chamber 1, and then the switch 13 is heated by CVD.
from the terminal 12a of the electrode 3 to the terminal 12 of the earth shield 4
b, and apply a high frequency to the shield 4. Then, the earth shield 4 serves as a plasma cleaning electrode, and the earth shield 4 acts as a plasma cleaning electrode, and the facing inner wall 1a and the chamber bottom 1 are connected to each other.
Plasma Pb is generated between Pb and Pb, and deposits adhering to the part of the inner surface of the chamber and the outer surface of the earth shield 4, which were difficult to plasma clean in the past, can be efficiently removed by etching.

As described above, in the plasma CVD apparatus according to the present invention, C
By using the ground shield that shields the back of the VD electrode as the plasma cleaning electrode, it is possible to greatly change the plasma generation area in the chamber, and with this, plasma cleaning can efficiently remove deposits from inside the chamber. It can be removed by etching.

Therefore, the inconvenience of having to open the chamber to the atmosphere every time a cleaning operation is performed can be eliminated at once.

In carrying out the present invention, the mechanism for providing the earth shield so that it can be insulated from the earth, and the mechanism for enabling the connection of the high frequency power source to be switched between the earth shield and the CVD electrode will of course be the same as described above. What is shown in the embodiment is merely an example, and other configurations may be adopted as appropriate.

Further, the plasma CVD apparatus to which the present invention is applied is not limited to the parallel plate type, but can generally be used as a counter electrode type having an earth shield.

[Effects of the Invention] As described above, in the plasma CVD apparatus of the present invention, since the earth shield is used also as a plasma cleaning electrode that forms a plasma generation area different from the CVD electrode, The feature is that deposits on the outer surface can be effectively removed by plasma cleaning, and the inside of the chamber does not have to be exposed to the atmosphere every time cleaning is performed.

[Brief explanation of drawings]

FIG. 1 and FIG. 2 show a plasma CV according to an embodiment of the present invention.
FIG. 1 is a schematic sectional view of the device D, in which FIG. 1 shows the CVD operating state and FIG. 2 shows the plasma cleaning operating state. FIG. 3 is a schematic cross-sectional view of a conventional plasma CVD apparatus.

Claims (1)

[Claims] Opposed electrode type plasma CVD in which a substrate and an electrode whose back surface is shielded by an earth shield are placed facing each other in a chamber.
A plasma CVD apparatus, characterized in that the earth shield is provided so as to be insulated from the earth, and a high frequency power source is provided so as to be switchable in connection between the earth shield and the electrode.