JP3034358B2 - Plasma processing equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention
The present invention relates to a plasma processing apparatus used when a source gas is decomposed to deposit a film on a substrate, or when a deposited film on a substrate is etched or surface-modified.

[0002]

2. Description of the Related Art As this type of plasma processing apparatus, there is known a plasma processing apparatus having a configuration shown in FIG. 7 or FIG. The conventional plasma processing apparatus shown in FIG. 7 has an exhaust port 703 opened in the inner wall 702 of the vacuum chamber 701.
03 is provided with a main exhaust valve 706 so as to be freely opened and closed. A required exhaust system 705 is connected to the outside of the exhaust port 703 via an exhaust passage 704. When the main exhaust valve 706 is opened, high vacuum exhaust can be performed on the chamber 701. it can. After being evacuated to a predetermined degree of vacuum in the vacuum chamber, a gas is introduced from the reaction gas system 716 through a passage 715, and the internal pressure of the chamber is maintained at a predetermined value by a pressure regulating valve (not shown). The high-frequency electrode 709 in the vacuum chamber is electrically insulated from the inner wall via an insulator 708, and generates plasma between the opposing electrode 712 and the opposing electrode 712. For this reason, an RF power supply 711 is connected to the electrode 709 via a lead 710, the counter electrode 712 is insulated from the inner wall 702 by an electric insulator 713, and a lead 714. Grounded.

The plasma processing apparatus shown in FIG. 8 has a function in which a high vacuum exhaust system and a reactive gas exhaust system are separated from each other.
Here, a main exhaust valve 806 is provided at an exhaust port 803 opened on the inner wall 802 of the vacuum chamber 801, and a reaction gas exhaust port 800 opened separately is provided. The exhaust port 803 communicates with an exhaust system 805 via an exhaust passage 804, and the exhaust port 800 communicates with an exhaust system 818 via an exhaust passage 817. After being evacuated to a predetermined degree of vacuum in the vacuum chamber, the reaction gas system 816
The gas is introduced through the passage 815, and the internal pressure of the chamber is maintained at a predetermined value by a pressure regulating valve (not shown). The high-frequency electrode 809 in the vacuum chamber is electrically insulated from the inner wall through an insulator 808, and generates plasma between the opposing electrode 812 and the opposing electrode 812. Therefore, an RF power source 811 is connected to the electrode 809 via a lead 810.
The counter electrode 812 is insulated from the inner wall 802 by an electric insulator 813 and is grounded via a lead 814.

[0004]

However, in the former case, the main exhaust valve 706 is kept open during plasma generation, and the ground potential at the exhaust port 703 is different from the inner wall of the chamber. This causes a change in the spatial distribution of the plasma. Therefore, a grounded mesh may be provided on the inner wall side of the chamber opposite to the main exhaust valve 706 so as not to hinder exhaust and to make the exhaust port 703 have the same potential as the inner wall 702. However, no substantial effect is obtained, and rather, depending on the mesh size, a discharge is generated in the mesh,
It causes the original plasma to be disturbed. Further, if the mesh is fine, the exhaust capacity is reduced due to an increase in exhaust resistance, and a problem arises in that a required degree of vacuum cannot be reached or a required amount of reaction gas cannot be flowed.

[0005] In the latter case, the reaction gas is supplied to the main exhaust valve 806.
When the air is exhausted through another exhaust port 800 in a closed state, the uniformity in the spatial distribution of the plasma can be slightly obtained, but the main exhaust valve is made of a non-conductive material such as a rubber O-ring. , It is difficult to make the same potential as the inner wall of the chamber. Particularly, in the case of RF plasma, when the main exhaust valve 806 is made of a material having a high impedance such as stainless steel, the potential difference becomes large. Therefore, it is conceivable to use a mesh as in the former case, but in this case, there is a problem as mentioned in the former. Also, the inner wall 802
The main exhaust valve 806 is not flush with the main exhaust valve 806, and unevenness at that location causes non-uniform plasma.

[0006]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention takes into account the shape of the exhaust valve body at the exhaust port and the potential difference between the exhaust valve and the vacuum chamber including the exhaust port.
It is an object of the present invention to provide a plasma processing apparatus capable of maintaining an inner wall at a constant potential and maintaining a stable and uniform plasma.

[0007]

That is, according to the present invention, in a plasma processing apparatus for performing a plasma process by a discharge phenomenon between electrodes disposed opposite to each other in a vacuum chamber, the plasma processing apparatus includes an inner wall of the vacuum chamber. In the provided exhaust port, a first valve body that is closed so as not to have irregularities with respect to the inner wall surface is provided so as to be openable and closable, the valve body is held at the same potential as the inner wall, Also, the hermetic second valve body is arranged outside the exhaust port.

[0008]

As a result, it is not necessary to arrange a mesh at the exhaust port, and the plasma can be maintained in a stable and uniform state.

[0009]

Next, one embodiment of the apparatus of the present invention will be described with reference to FIGS. In the plasma processing apparatus of the present invention, as shown in FIG. 1, an exhaust port is opened in the inner wall (side wall) 102 of the vacuum chamber 101, and the vacuum chamber 101 is formed in a box shape through the exhaust port. It communicates with the exhaust unit 120. The exhaust port has a peripheral edge that expands and inclines toward the exhaust unit 120 side, and a first valve body 121 fitted at the peripheral edge is provided as an exhaust valve on the exhaust port so as to be openable and closable. . in this case,
The surface of the valve body 121 facing the inside of the vacuum chamber 101 is flush with the inner wall 102, and the shape of the location is such that the plasma is not disturbed. The valve body 121 has a flange-shaped edge 121A, on which a grounding member 122 made of a good electric conductor is attached, and is in contact with the outside of the vacuum chamber to stably and uniformly distribute the plasma. , The valve body 121 is set to the same potential as the inner wall 102.

The grounding member 122 is made of a copper plate having a U-shaped cushion as shown in FIG. 3 or 4, and is screwed to the valve body 121. Alternatively, as shown in FIG. As shown, an alternative hollow metal ring gasket 123 may be used. Or
As shown in FIG. 6, a structure in which both are combined may be adopted.

Further, in the present invention, an exhaust port 103 is provided outside the exhaust port toward the outside of the exhaust unit 120, and an airtight second valve body 106 is provided here. Is arranged.

In this embodiment, the plasma processing apparatus according to the present invention has a high vacuum exhaust system and a reactive gas exhaust system separated in function. In this embodiment, an exhaust port opened on the inner wall 102 of the vacuum chamber 101 is provided. Separately, the reaction gas exhaust port 10
0 is provided. The exhaust port 103 is connected to the exhaust passage 1
04 to the exhaust system 105 and the exhaust port 100
Communicates with an exhaust system 118 via an exhaust passage 117. In the vacuum chamber 101, after being evacuated to a predetermined degree of vacuum, a gas is introduced from the reaction gas system 116 through the passage 115, and the internal pressure of the chamber is maintained at a predetermined value by a pressure regulating valve (not shown). . The high-frequency electrode 109 in the vacuum chamber is electrically insulated from the inner wall through an insulator 108 and generates plasma between the opposing electrode 112 and the opposing electrode 112. Therefore, the electrode 109 is not connected to the lead.
The counter electrode 112 is insulated from the inner wall 102 by an electric insulator 113, and is grounded via a lead 114.

The case where RIE mode etching is performed using such an apparatus will be described below.
After a substrate (not shown) is placed on the electrode 109, the valve body 12
The vacuum chambers 1 and 106 are opened, and the vacuum system 101 is evacuated from the vacuum chamber 101 via the exhaust unit 120 using the exhaust system 105 to reduce the pressure in the chamber 101 to a predetermined degree of vacuum. Next, the valve 106 is closed, and an etching reaction gas, for example, CF ₄ or the like is introduced from the reaction gas system 116 into the chamber 101. As a result, the etching gas is maintained at the pressure set by the pressure regulating valve (not shown) while maintaining the chamber internal pressure.
01 and the exhaust unit 120, and the exhaust system 117
Exhausted through. When a predetermined pressure is reached, the valve body 121 is closed, a voltage is applied between the electrodes 109 and 112, and plasma is generated in the chamber 101. As a result, the deposited film on the substrate is etched from the reaction gas to a predetermined thickness. In this case, the inner wall 10
2 and the valve element 121 are kept at the same potential, and there is no unevenness on the surface, so that the spatial distribution of plasma in the chamber 101 is maintained uniformly and is not disturbed. In particular,
In this embodiment, since the reaction gas is uniformly exhausted through the exhaust port 100 even during the generation of the plasma, the plasma is stably held without fluctuation and uniform etching is performed. When the etching is performed to the predetermined thickness, the supply of the electric power is stopped, and the supply of the reaction gas is stopped. Thereafter, the valve element 121 is opened, the chamber 101 and the exhaust unit 120 are exhausted by the exhaust system 118, and at the stage where the pressure is reduced to a predetermined pressure, the valve element 106 is opened and the next vacuum exhaust is performed.

For example, when an a-Si film on a substrate is etched using CF ₄ gas, if the supply power is 500 W, the etching pressure is 109 a, and the CF ₄ gas flow rate is 100 SCCM, the etching rate is as shown in FIG. Distribution is 400
In the corner substrate, it can be confirmed that the improvement is within ± 5%.

The valve body 121 is preferably made of aluminum in consideration of impedance, and the grounding member 122 is preferably made of phosphor bronze. When the valve body 121 is made of a material having a high impedance such as stainless steel, a low impedance material such as phosphor bronze, aluminum and copper is formed on the entire back surface of the valve body 121 as in the embodiment of FIG. It may be covered with. In terms of sealing,
As shown in FIG. 5 and the like, the use of a hollow metal ring gasket 123 as a grounding member is also effective if necessary.

[0016]

As described in the above embodiments, according to the plasma processing apparatus of the present invention, the plasma processing apparatus performs the plasma processing by the discharge phenomenon between the electrodes disposed opposite to each other in the vacuum chamber. In the exhaust port provided on the inner wall of the vacuum chamber, a first valve body which is closed so as not to have irregularities with respect to the inner wall surface is provided so as to be openable and closable, and the valve body is set to the same potential as the inner wall. Since the holding and the second valve body of the sealing type are arranged outside the exhaust port from the valve body, the inner wall of the vacuum chamber including the exhaust port portion is maintained at a constant potential, and the plasma is discharged. It can be maintained in a stable and uniform state.

[Brief description of the drawings]

FIG. 1 is a schematic view of an embodiment of a film forming apparatus for carrying out the present invention.

FIG. 2 is a graph showing an etching rate in the present invention.

FIG. 3 is a vertical sectional side view showing a grounding means of the valve body according to the present invention.

FIG. 4 is a vertical sectional side view showing a grounding means of the valve element according to the present invention.

FIG. 5 is a vertical sectional side view showing a grounding means of the valve element according to the present invention.

FIG. 6 is a vertical sectional side view showing a grounding means of the valve element according to the present invention.

FIG. 7 is a schematic view of a conventional plasma processing apparatus.

FIG. 8 is a schematic diagram of a conventional plasma processing apparatus.

[Explanation of symbols]

 Reference Signs List 101 vacuum chamber 102 inner wall 103 exhaust port 106 second valve element 109, 112 high-frequency electrode 120 exhaust unit 121 first valve element 122 ground member

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) H01L 21/205 C23C 16/50 C23F 4/00 H01L 21/3065

Claims (1)

(57) [Claims] 1. A plasma processing apparatus for performing a plasma process by a discharge phenomenon between electrodes disposed opposite to each other in a vacuum chamber, wherein an exhaust port provided on an inner wall of the vacuum chamber has And a first valve element that is closed so as to be free of irregularities is provided so as to be openable and closable, the valve element is held at the same potential as the inner wall, and a hermetically sealed second port is provided outside the exhaust port with respect to the valve element. A plasma processing apparatus comprising a valve body.