JP3916469B2 - Plasma processing equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a plasma processing apparatus (plasma reactor) such as a plasma film forming apparatus or a plasma etching apparatus, and relates to a wafer or panel in a manufacturing process of an IC (semiconductor device), an LCD (liquid crystal display panel), or a PDP (plasma display panel). The present invention relates to a plasma processing apparatus suitable for performing plasma processing, that is, processing based on a plasma reaction.
[0002]
Examples of plasma processing performed by exposing an object to be processed to a plasma atmosphere in a vacuum chamber include etching, ashing, and plasma CVD. As a typical example of a plasma processing apparatus used for these processes, a pair of electrodes facing each other is provided, and a plasma processing space is formed between the electrodes to form an object to be processed (processing substrate) such as a silicon wafer. A so-called parallel plate type etcher (RIE) for performing an etching process and a parallel plate type PCVD for performing a film forming process are known.
[0003]
[Prior art]
FIG. 2 (a) shows a schematic longitudinal sectional view of the overall configuration of the apparatus. In the parallel plate type plasma processing apparatus, a pair of parallel plates are provided in a vacuum chamber and formed between both plates. Plasma is generated or introduced into the plasma processing space, and a predetermined processing gas or the like is also introduced into the plasma processing space. Then, a plasma reaction is performed in the plasma processing space, whereby an etching process or the like is performed on the surface of the object to be processed in the plasma processing space.
[0004]
Specifically (see FIG. 2 and Japanese Patent Application Laid-Open No. 10-294307), the vacuum chamber surrounding the plasma processing space 4 is made of a good electrical conductor such as aluminum, and the vacuum chamber lid 3 is attached to the vacuum chamber body 2. It can be opened and closed. On the inner bottom of the vacuum chamber body 2, a holding electrode 5 is implanted so that the processing substrate 1 carried into the chamber is placed on the upper surface so as to face and hold the plasma processing space 4. 3, a counter electrode 6 facing the holding electrode 5 with a plasma processing space 4 in between is suspended. An adjacent insulator 10 made of ceramic or the like is attached on the counter electrode 6. On the lower surface of the adjacent insulator 10, the plasma generation space 10a is engraved and formed in a multiple annular shape or polygonal shape, and the coil 7 is stored in a groove formed by engraving alternately from above.
[0005]
In addition, the vacuum chamber 2 + 3 is provided with a vacuum pump, a variable valve, etc. for evacuating the plasma processing space 4 and controlling its pressure, and a high frequency of about 500 KHz to 2 MHz is applied to the lower holding electrode 5. An RF power source 9 for applying a bias voltage and an RF power source 8 (first applying means) for applying a high frequency of about 13 MHz to 100 MHz to the coil 7 described above for excitation and formation of plasma are also provided. Further, through the upper counter electrode 6, specifically, through the flow path formed in the adjacent insulator 10 and the counter electrode 6, a plasma gas A such as argon used for plasma generation and excitation is supplied. A gas unit and a gas unit for supplying a processing gas B such as silane gas used as a reaction gas are also provided.
[0006]
Then, according to the process recipe or the like, a high frequency is applied from the RF power source 8 to the coil 7 while feeding the plasma gas A into the plasma generation space 10a. As a result, plasma A ′ is generated in the plasma generation space 10 a and flows from the plasma supply port 6 a formed dispersedly in the counter electrode 6 to the plasma processing space 4. When the plasma processing space 4 is filled with plasma, when the processing gas B is sent to the plasma processing space 4 through the processing gas supply ports 6b formed dispersedly in the counter electrode 6, a desired plasma processing is performed on the processing substrate 1. Is given.
[0007]
At that time, anisotropy is imparted to the plasma processing by applying an appropriate bias voltage to the holding electrode 5 by the RF power source 9.
On the other hand, the counter electrode 6 was grounded.
[0008]
[Problems to be solved by the invention]
However, if a bias voltage is also applied to the counter electrode, it does not directly affect the plasma treatment, but the amount of plasma by-products and the like attached to the counter electrode can be reduced. In addition, when a nonmetal such as silicon is provided at the counter electrode, the amount of carbon or the like attached to the counter electrode can be reduced. In view of this, it is conceivable to attach a non-metal to the metal counter electrode so as to eliminate unwanted adhesion to the counter electrode as much as possible.
[0009]
However, good electrical conductors that are convenient for electrodes generally have a high coefficient of thermal expansion, whereas most non-metals have a low coefficient of thermal expansion. And it is easy to be distorted or damaged by the heat accompanying the plasma treatment. For this reason, a counter electrode and a nonmetal cannot be simply combined.
Therefore, it is a technical problem to devise the structure of the counter electrode so that distortion and damage do not occur when the non-metal is bonded to the metal counter electrode.
The present invention has been made to solve such a problem, and an object thereof is to realize a plasma processing apparatus with less adhesion to the counter electrode.
[0010]
[Means for Solving the Problems]
About the 1st thru | or 3rd solution means invented in order to solve such a subject, the structure and effect are demonstrated below.
[0011]
[First Solution]
In the plasma processing apparatus of the first solution, as described in claim 1 at the beginning of the application, the counter electrode facing the holding electrode for holding the processing substrate in the vacuum chamber across the plasma processing space is made of a good electrical conductor. One type of metal member, a second type of metal member having a different coefficient of thermal expansion, and a non-metal member facing the plasma processing space are overlaid.
[0012]
Specifically, as described in claim 2 at the beginning of the application, a vacuum chamber that surrounds the plasma processing space, a holding electrode that holds the processing substrate facing the plasma processing space, and the plasma processing space across the plasma processing space. A counter electrode facing the holding electrode; means for supplying a plasma gas and a processing gas to the plasma processing space through the counter electrode; and applying a high frequency power to a coil attached to the counter electrode to excite the plasma gas. In the plasma processing apparatus including the first applying means, the second applying means for applying high-frequency power to the counter electrode is provided, and the counter electrode is provided with a first type metal member made of a good electric conductor, and heat A second type metal member having a different expansion coefficient and a non-metal member facing the plasma processing space are overlapped with each other.
[0013]
In such a plasma processing apparatus of the first solution, the electrode function of the counter electrode is secured by the first type metal member, the plasma exposed surface is covered by the non-metal member, and the heat of both Distortion and damage due to the difference in expansion coefficient are alleviated by the intervention of the second type metal member.
As a result, the counter electrode in which the metal and the nonmetal are bonded together is configured without any inconvenience.
Therefore, according to the present invention, it is possible to realize a plasma processing apparatus with less adhesion to the counter electrode.
[0014]
[Second Solution]
The plasma processing apparatus of the second solving means is the plasma processing apparatus of the first solving means as described in claim 3 at the beginning of the application, wherein the second type metal member and the non-metallic member are provided. It is said that an adhesive or other filler is filled in between.
[0015]
In such a plasma processing apparatus of the second solving means, when the temperature of the non-metallic member rises due to the generation of plasma or the like, the heat is transferred to the metallic member efficiently through the filler. Is done. Since the metal member generally has good heat transfer, the temperature rise of the non-metal member can be suppressed well. Thereby, since thermal distortion further decreases, shape design, member selection, etc. become easy.
Therefore, according to the present invention, it is possible to easily realize a plasma processing apparatus with less adhesion to the counter electrode.
[0016]
[Third Solution]
The plasma processing apparatus of the third solving means is the plasma processing apparatus of the second solving means described in claim 4 at the beginning of the application, wherein the second applying means applies the application of high-frequency power. This is to be applied to the second type metal member.
[0017]
In such a plasma processing apparatus of the third solving means, since a high frequency is applied to the second type metal member adjacent to the nonmetallic member, the nonmetallic member having the plasma exposed surface is used. On the other hand, the bias voltage is efficiently applied.
Thereby, even if the second type metal member is interposed, the effect of reducing the adhesion amount by applying the bias voltage with respect to the counter electrode is maintained and strengthened.
Therefore, according to the present invention, it is possible to easily realize a plasma processing apparatus with particularly little adhesion to the counter electrode.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
With regard to the plasma processing apparatus of the present invention achieved by such a solution, a mode for carrying out this will be specifically described by way of an example.
First, a specific configuration thereof will be described with reference to the drawings. FIG. 1 shows a longitudinal sectional structure of a counter electrode as a main part, in which (a) is an entire electrode and (b) is a partially enlarged view. FIG. In the illustration, fasteners, adhesives, gas pipes, buried filters, O-rings, etc. are omitted. In addition, since the same reference numerals are given to the same components as those in the prior art, the repeated description will be omitted, and hereinafter, the differences from the prior art will be mainly described.
[0019]
This plasma processing apparatus is different from the conventional one in that the counter electrode 6 is remodeled into a counter electrode 60 and an RF power source 67 (second applying means) is added. Note that magnets are omitted with emphasis on increasing plasma uniformity and cleanliness by increasing plasma density.
The RF power source 67 outputs a high frequency of about 500 KHz to 2 MHz similarly to the RF power source 9. However, unlike the RF power source 9, the RF power source 67 is for applying a bias voltage to the upper counter electrode 60.
[0020]
The counter electrode 60 includes, from top to bottom, an aluminum plate 61 (first type metal member), an aluminum plate 62 (first type metal member), a molybdenum plate 63 (second type metal member), and a silicon plate 64 ( The non-metal member is superposed on the side surface, and the periphery of the side surface is covered with an insulating ring 65 so as not to be electrically short-circuited with the grounded vacuum chamber 2 + 3.
[0021]
The aluminum plate 61 and the aluminum plate 62 are good electrical conductors, and a mesh-like groove is formed by engraving them together, and the gas flow path penetrating both the plates 61 and 62 is made to communicate therewith. It is concentrated at the upper surface of the plate 61 and dispersed at the lower surface of the aluminum plate 62. This is the case for each of the plasma gas A and the processing gas B. Further, a hole through which the power supply line from the RF power supply 8 is inserted and a hole through which the power supply line extending from the RF power supply 67 is inserted through both the plates 61 and 62 are also formed.
[0022]
The molybdenum plate 63 has a thermal expansion coefficient smaller than that of aluminum and close to that of silicon, and also has a good thermal conductivity. In this, copper plugs 66 are dispersed and installed in several places, and a power supply line from an RF power source 67 is connected thereto, and the application of high frequency power by the RF power source 67 is applied to the molybdenum plate 63. It is supposed to be done. The flow paths of the gases A and B are also formed so as to penetrate each other.
[0023]
The silicon plate 64 is located at the lowest position in the counter electrode 60 and faces the plasma processing space 4. The groove for storing the coil 7 is transferred from the adjacent insulator 10 to the silicon plate 64 and is formed by engraving on the upper surface thereof. The plasma generation space 10 a is also transferred to the silicon plate 64, and a plasma generation space 60 a in place of the plasma generation space 10 a and the plasma supply port 6 a is engraved on the lower surface of the silicon plate 64. The plasma supply port of the plasma generation space 60a is greatly open toward the plasma processing space 4 with an emphasis on increasing the plasma uniformity and cleanliness by increasing the plasma density.
[0024]
The groove for storing the coil 7 and the plasma generation space 60a are alternately dispersed to form, for example, concentric circles and spirals (see also Japanese Patent Laid-Open No. 10-294307), and the plasma gas A is the plasma generation space 60a. The processing gas B flows into the plasma processing space 4 from between them while avoiding the plasma generation space 60a.
[0025]
Such a silicon plate 64 is adhered to the molybdenum plate 63 with an adhesive, for example, and is fixed to the aluminum plate 62 and the aluminum plate 61 together with the molybdenum plate 63 with bolts or the like. In order to improve the heat conduction between the molybdenum plate 63 and the silicon plate 64 and relieve the stress at the time of thermal expansion, a silicon adhesive having excellent thermal conductivity and elongation is suitable as the adhesive. The adhesive may be used. In addition, when bonding the silicon plate 64 and the molybdenum plate 63 with a fastener or locking means, an adhesive may be used in combination, but instead of the adhesive, the deformability and heat resistance are also improved. May be filled with excellent silicon rubber or the like.
[0026]
The use mode and operation of the plasma processing apparatus having such a configuration will be described.
[0027]
When the processing substrate 1 is loaded onto the holding electrode 5 and the plasma processing space 4 is evacuated, the plasma gas A is sent into the plasma generation space 60a in accordance with the process recipe and the like, and the RF power source 8 supplies a high frequency to the coil 7. Is applied. Thereby, plasma A ′ is generated in the plasma generation space 60 a and flows into the plasma processing space 4. When the plasma processing space 4 is filled with plasma, the processing gas B is sent from the processing gas supply port 6b to the plasma processing space 4 through a flow path different from the plasma gas A. Also, a high frequency is applied to the molybdenum plate 63 from the RF power source 67, whereby a bias voltage is directly induced on the molybdenum plate 63 and at the same time a bias voltage is induced on the silicon plate 64.
[0028]
Thus, a desired plasma process using the processing gas B is performed on the processing substrate 1. At this time, even if a by-product such as carbon is generated, the plasma exposed surface of the counter electrode 60 is not aluminum but silicon, and a bias voltage is applied thereto, so that the counter electrode 60 such as carbon is applied to the counter electrode 60. Adhesion is prevented. Furthermore, the heat of the silicon plate 64 is efficiently transferred to the molybdenum plate 63 through the thin filler, and escapes to the aluminum plates 62 and 61 while being uniformed there, so that the silicon plate 64 can be prevented from excessive temperature rise. In addition, the heat distribution becomes almost uniform. In addition, since the coefficient of thermal expansion is close to that of the molybdenum plate 63 to be bonded, it expands and contracts together with the molybdenum plate 63, so that an undesired pulling force is not applied to the bonded surface or less. Therefore, the silicon plate 64 is not distorted or damaged, and it is only slight. In addition, the uniformity of the plasma distribution is improved, and there is an effect that the plasma processing is improved.
[0029]
[Others]
In the above-described embodiment, the holding electrode 5 and the counter electrode 60 have a parallel plate shape. However, the application of the present invention is not limited to this, and one or both may be slightly curved. Moreover, as long as it adapts to the shape of the processing substrate 1, it may be round or square.
[0030]
【The invention's effect】
As is apparent from the above description, in the plasma processing apparatus of the first solving means of the present invention, when a counter electrode is formed by bonding a metal and a non-metal, another metal is interposed, By reducing the influence of the difference in expansion coefficient, there is an advantageous effect that a plasma processing apparatus with less adhesion to the counter electrode can be realized.
[0031]
Further, in the plasma processing apparatus of the second solving means of the present invention, the temperature increase of the nonmetallic member is suppressed by filling, thereby realizing a plasma processing apparatus with less adhesion to the counter electrode. There is an advantageous effect that it becomes easy.
[0032]
Further, in the plasma processing apparatus of the third solving means of the present invention, a plasma processing apparatus with particularly low adhesion to the counter electrode is obtained by applying a bias voltage to the nonmetallic member efficiently. There is an advantageous effect that it can be easily realized.
[Brief description of the drawings]
FIG. 1 shows a longitudinal sectional structure of a counter electrode of an embodiment of a plasma processing apparatus of the present invention, wherein (a) is an entire electrode and (b) is a partially enlarged view.
2A and 2B show a longitudinal sectional structure of a conventional device, in which FIG. 2A is a general view of a vacuum chamber, and FIG. 2B is a longitudinal sectional perspective view of a counter electrode and the like.
[Explanation of symbols]
1. Processing substrate (wafer, target plate, sample, workpiece)
2 Vacuum chamber body (vacuum chamber)
3 Vacuum chamber lid (vacuum chamber)
4 Plasma treatment space 5 Holding electrode (cathode, one of the pair of electrodes, lower electrode for mounting the workpiece)
6 Counter electrode (anode, the other of the pair of electrodes, the upper electrode facing the workpiece)
6a Plasma supply port 6b Process gas supply port 7 Coil (High frequency application circuit for plasma excitation, first applying means)
8 RF power supply (high frequency power supply for plasma excitation, first applying means)
9 RF power supply (High-frequency applying circuit for holding electrode bias, third applying means)
10 Adjacent insulator (plasma generation chamber)
10a Plasma generation space 60 Counter electrode (the anode, the other of the parallel plates, the upper electrode facing the object to be processed)
60a Plasma generation space 61 Aluminum plate (annular passage lid, first type metal member)
62 Aluminum plate (annular base, first type metal member)
63 Molybdenum plate (Type 2 metal member)
64 Silicon plate (non-metallic member)
65 Insulating ring 66 Copper plug (Counter electrode bias high-frequency applying circuit, second applying means)
67 RF power supply (high frequency application circuit for counter electrode bias, second application means)

Claims (2)

A vacuum chamber surrounding the plasma processing space;
A holding electrode that holds the processing substrate facing the plasma processing space;
A counter electrode facing the holding electrode across the plasma processing space ;
Means for supplying a plasma gas to the plasma processing space through the counter electrode;
First application means for exciting the plasma gas by applying high frequency power to a coil attached to the counter electrode;
A plasma processing apparatus comprising: a second application unit that applies high-frequency power to the counter electrode;
A first type metal member in which the counter electrode is made of a good electric conductor;
A second type metal member having a smaller coefficient of thermal expansion than the first type metal member;
Consists of superposed non-metallic members facing the plasma processing space ,
The plasma processing apparatus, wherein the second applying means applies high frequency power to the second type metal member . The plasma processing apparatus according to claim 1, wherein the non-metallic member is made of silicon .

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