JP2005260186A - Plasma process apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a plasma process apparatus capable of giving different plasma energy according to the kind of gas for plasma treatment. <P>SOLUTION: The invention comprises a gas supply portion for supplying gas G1 and G2 for plasma treatment to a vacuum container 50 and a plasma generation portion 15 for generating plasma in the vacuum container 50. In a plasma CVD apparatus 60 for applying the plasma treatment to a deposition substrate 2 in the vacuum container 50, the plasma generation portion 15 is provided on a position away from the deposition substrate 2 such that a plurality of plasma regions 10a and 10b different in region area are formed. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a plasma processing apparatus for performing plasma processing on a substrate to be processed. More specifically, the present invention relates to a chemical vapor deposition method (CVD) used for forming a semiconductor film such as amorphous silicon or an insulating film in the electronic industry. The present invention relates to a plasma process apparatus suitable as a thin film forming apparatus, a dry etching apparatus, an ashing apparatus and the like using the (Chemical Vapor Deposition) method.

  In the conventional CVD method, plasma is generated by applying high-frequency or low-frequency power to the material gas to activate the material gas, or thermal CVD in which the material gas is pyrolyzed by thermal energy. There are laws.

  Since the CVD method is excellent in simplicity and operability, it is used for film formation of semiconductor films and insulating films of various electronic devices such as integrated circuits, liquid crystal displays, organic electroluminescence elements, and solar cells.

  For such film formation, a parallel plate type plasma CVD apparatus is generally used (see Patent Document 1). This parallel plate type plasma CVD apparatus is a system in which a plurality of gas inlets are provided in an electrode substrate disposed opposite to a substrate to be processed (film formation substrate) 102, and a source gas is blown from these gas inlets to the substrate side. This is a plasma CVD apparatus.

  Specifically, FIG. 5 is a diagram showing a schematic configuration of a conventional flat plate parallel plasma CVD apparatus. In this plasma CVD apparatus, two conductive plates that are electrically insulated from each other are provided in a processing chamber (vacuum vessel) 150 in a closed space that is evacuated by a vacuum pump 155. One of the conductor plates is provided on the film formation substrate 102 side, and the other is opposed to the film formation substrate 102 and is provided at a distance from the conductor on the film formation substrate 102 side. They are arranged in parallel. That is, one of the conductor plates is a cathode electrode 117 to which a high frequency voltage is applied, and the other is attached along the side surfaces of the film formation substrate 102 and the substrate holder 113 and is grounded to the lower part of the processing chamber 150. This is the anode electrode 113. Note that an insulating film 118 is formed on the surface of the cathode electrode 117 on the film formation substrate 102 side.

  In this plasma CVD apparatus, when a high frequency voltage is applied to the cathode electrode 117, plasma is generated in the plasma region 110 between the cathode electrode 117 and the anode electrode 113. When a material gas G, which is a film forming material, is supplied to the plasma from the gas supply unit 154, the material gas G is separated and dissociated in the plasma region 110, and a radical R of the material gas G is generated. Then, the radical R is deposited on a film formation substrate 102 (such as a silicon substrate or a glass substrate) to which the anode electrode 113 is attached, whereby a semiconductor film, an insulating film, or the like is formed on the film formation substrate 102. The

  Here, as the plasma for decomposing the material gas G, if a high frequency voltage of 13.56 MHz is applied to the cathode electrode 117 under a low pressure to generate an electric field, the dielectric breakdown phenomenon causes a glow discharge. Plasma can be generated in the plasma region 110. Then, the plasma generated between the cathode electrode 117 and the anode electrode 113 causes the electrons to promote the dissociation of the material gas G to generate radicals R, which radicals R are formed on the deposition substrate 102 on the anode electrode 113 at the ground potential. And is deposited on the surface of the deposition substrate 102.

  However, in the parallel plate type plasma CVD apparatus, a plasma region 110 in which plasma is generated is formed between the electrodes, so that the deposition substrate is exposed to the plasma region 110. For this reason, in this apparatus, there is a problem that sheath voltage is likely to be generated and the film quality of the surface of the thin film formed on the substrate to be processed is deteriorated.

In order to solve this problem, there is a remote plasma CVD apparatus as another apparatus using the plasma CVD method (for example, Patent Document 2). The basic apparatus configuration of the remote plasma CVD apparatus is the same as that of the parallel plate CVD apparatus shown in FIG. 5, but the grounded electrode (anode electrode 113) is formed at a position away from the film formation substrate 112. It is characteristic that it is. With such a remote plasma structure, the plasma space can be formed at a position away from the film formation substrate 102, so that ion bombardment (influence of the sheath) in the plasma can be avoided. A high frequency voltage is applied to the cathode electrode under a low pressure as a material gas for film formation to generate an electric field, and plasma is generated as a glow discharge by the dielectric breakdown phenomenon. Electrons in the plasma promote the dissociation of the material gas, generate radicals, diffuse to the deposition substrate, and deposit on the film surface.
JP-A-5-166728 (publication date: July 2, 1993) Japanese Patent Laid-Open No. 5-21393 (Publication date: January 29, 1993)

  However, the remote plasma CVD apparatus has a problem that different energy cannot be given depending on the type of material gas.

  Specifically, normally, in a plasma CVD apparatus, film formation is performed using a plurality of material gases. The remote plasma plasma CVD apparatus is configured to decompose a plurality of material gases in the same space. However, the degree of dissociation and decomposition efficiency for generating radicals from the material gas vary greatly depending on the type of material gas. For this reason, in a remote plasma CVD apparatus, different energy cannot be given according to the kind of material gas. As a result, when forming a thin film using a plurality of different types of material gases, it becomes difficult to control the composition of each material gas in the thin film. Moreover, the utilization efficiency of material gas with low decomposition efficiency also becomes low.

  Therefore, it is necessary to give different plasma energy depending on the type of material gas.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a plasma processing apparatus capable of giving different plasma energy depending on the kind of gas for plasma processing. .

  In order to solve the above problems, a plasma processing apparatus according to the present invention is provided at a position away from a processing substrate, a gas supply unit that supplies a plasma processing gas to the processing chamber, and a substrate to be processed. A plasma generating unit for generating plasma in a processing chamber, and performing plasma processing on a substrate to be processed in the processing chamber, wherein the plasma generating unit includes a plurality of plasma regions having different area areas. It is characterized by having.

  According to said structure, the plasma generation part is provided in the position away from the to-be-processed substrate. That is, a plasma region is formed at a position away from the substrate to be processed. As a result, the substrate to be processed is not exposed to the plasma region. For this reason, it is possible to avoid the plasma (plasma ions) accelerated in the plasma region from colliding with the substrate to be processed. Therefore, deterioration of the film quality of the substrate to be processed due to plasma can be prevented.

  And especially in said structure, it has a plasma area | region from which an area | region area differs in a plasma generation part. For this reason, plasmas having different energies are generated in the plasma region.

  In plasma processing, a plurality of material gases (plasma processing gases) are often used in combination. However, the dissociation degree and decomposition efficiency of the material gas vary greatly depending on the type of material gas. For this reason, when the same energy is given to a plurality of types of material gases, the separation and dissociation of the material gases by plasma become non-uniform, and the generated radicals become non-uniform. As a result, radicals that are not used for the plasma treatment are generated, and the energy utilization efficiency is deteriorated. For this reason, the throughput of the plasma processing is also lowered.

  In the above configuration, plasmas having different energies are generated in a plurality of plasma regions having different area areas, so that different energies can be applied to a plurality of types of material gases. That is, since it has a plurality of plasma regions having different region areas, it is possible to form different electric fields in the region with the same power source, for example. Thereby, different energy can be given according to material gas. As a result, the material gas can be uniformly separated and dissociated to generate uniform radicals. Accordingly, it is possible to efficiently use energy and improve the throughput of plasma processing.

  The “plasma treatment” means that a material gas is separated and dissociated by plasma to generate radicals, and the substrate to be processed is subjected to processing such as film formation and processing by the radicals. For example, a film formation (thin film formation) process for depositing radicals on the substrate to be processed, an etching process for finely processing a metal or a film on the substrate to be processed, an ashing process for removing the resist on the substrate to be processed, and the like can be given.

  Therefore, the plasma process apparatus includes at least a film forming apparatus (thin film forming apparatus), an etching apparatus, and an ashing apparatus. The plasma processing gas includes at least a gas used in these apparatuses.

  Further, the “plasma region” is a region where plasma discharge occurs (a region where plasma is generated) in the plasma generation unit. Note that the plasma processing gas is decomposed in the plasma region to generate radicals.

  In the plasma processing apparatus of the present invention, the plasma generation unit is a first electrode and a counter electrode of the first electrode, which are insulated from each other, and is provided closer to the substrate to be processed than the first electrode. The first electrode includes electrodes that are insulated from each other and have different distances from the second electrode.

  According to said structure, the plasma generation part has a 1st electrode and a 2nd electrode, and the 1st electrode is comprised from the several electrode from which the distance from a 2nd electrode differs. The first electrode, the second electrode, and the plurality of electrodes of the first electrode are insulated. As a result, a plasma region is formed between the first electrode and the second electrode. That is, the plasma region is a portion surrounded by the plasma discharge surface of the first electrode and the plasma discharge surface of the second electrode. Accordingly, plasma regions having different area areas are formed by the plurality of types of first electrodes having different distances from the second electrode. As a result, plasmas having different energies are generated in accordance with the arrangement state of the first electrodes with respect to the second electrodes, so that different energies can be given to a plurality of types of material gases. Thereby, different energy can be given according to material gas.

  The “plasma discharge surface” means the surfaces of the first electrode and the second electrode that substantially function as a discharge electrode.

  Moreover, the plasma process apparatus of the present invention is characterized in that the plasma discharge surfaces of the first electrode and the second electrode are composed of portions that can be viewed from the surface to be processed of the substrate to be processed.

  According to said structure, a plasma discharge surface is formed from the part which can be visually recognized from a to-be-processed substrate. In other words, the first electrode and the second electrode are arranged so as not to overlap when viewed from the normal direction of the substrate to be processed. That is, the plasma discharge surface of the first electrode and the plasma discharge surface of the second electrode are arranged so as not to face each other. Thereby, it can prevent that a plasma generate | occur | produces on the surface where the plasma discharge surface of a 1st electrode and a 2nd electrode opposes. That is, it is possible to prevent a thin film from being formed on the surfaces of the first electrode and the second electrode that are opposed to the plasma discharge surface. Therefore, radicals generated by decomposing the material gas can be efficiently guided onto the substrate to be processed.

  Moreover, the plasma process apparatus of the present invention is characterized in that the second electrode is disposed on an insulator provided between the first electrodes.

  According to said structure, since the said 2nd electrode is arrange | positioned on the insulator provided between the said 1st electrodes, a plasma area | region is the plasma discharge surface of a 1st electrode and a 2nd electrode, and The region is surrounded by an insulator. That is, the plasma region is formed as a concave shape, for example. Thus, the first electrode and the second electrode are integrally formed via the insulator. Therefore, the configuration of the plasma generation unit can be simplified.

  In addition, since the first electrode and the second electrode are provided via an insulator, it is possible to prevent plasma from being generated on the surfaces of the first electrode and the second electrode that are opposed to the plasma discharge surface. That is, it is possible to prevent a thin film from being formed on the surfaces of the first electrode and the second electrode that are opposed to the plasma discharge surface. Therefore, radicals generated by decomposing the material gas can be efficiently guided onto the substrate to be processed.

  In the plasma processing apparatus of the present invention, the first electrode has a plasma discharge surface having a concave cross section. Thereby, since the area of the plasma discharge surface of the first electrode can be increased, it is possible to reduce the disappearance of plasma and radicals generated in the first electrode. Moreover, since the cross section is concave, a hollow cathode effect (an effect of obtaining high-density plasma) is also obtained.

Also, the plasma process apparatus of the present invention, in the first electrode, satisfies the distance d _1> d ₂ from the second electrode to the plurality of electrodes, the electrodes of the distance d _2, the distance d ₁ It has the 1st energy supply part which supplies electric energy larger than an electrode, It is characterized by the above-mentioned.

According to the above configuration, the first energy supply unit, the electrode closer to the second electrode of the first electrode (the distance d ₂ of the electrode), supply the high electrical energy. Thus, it is possible to generate more plasma energy at the electrode distance d _2. Therefore, the degree of gas dissociation (radical generation rate) at the electrode of the distance d ₂ can be further improved.

Note that “a plurality of electrodes satisfying the distance d ₁ > d ₂ from the second electrode in the first electrode” means that the first electrode includes two electrodes satisfying the distance d ₁ > d _2. It indicates that there is an electrode satisfying the distance d ₁ > d ₂ in any of a plurality of electrodes.

  The plasma processing apparatus of the present invention is characterized in that the first electrode is provided with a second energy supply unit that supplies the same electric energy.

  According to said structure, since an energy supply part supplies the same electrical energy to a 1st electrode, it is not necessary to provide the energy supply part of a different electrical energy. For this reason, the structure of an energy supply part can be simplified.

  In the plasma processing apparatus of the present invention, the electrical energy is selected from a frequency region of 100 kHz or more and 300 MHz or less.

  Thereby, stable discharge is possible with the first electrode, and the uniformity of the film thickness is improved. It is also effective in increasing the degree of gas dissociation (radical generation rate) at the first electrode.

  The plasma processing apparatus of the present invention is characterized by comprising a gas introduction path for guiding the plasma processing gas to the plasma generating section independently for each type of the plasma processing gas.

  Thereby, different types of gases can be reliably supplied to plasma regions having different region areas. Therefore, plasma energy can be given according to the degree of separation / dissociation of the plasma processing gas.

  The plasma process apparatus of the present invention is characterized in that the gas introduction path guides the plasma processing gas to the first electrode side.

  According to said structure, the gas for plasma processing supplied from a gas supply part is guide | induced to the 1st electrode side through the said gas introduction path | route. The second electrode is closer to the substrate to be processed than the first electrode. Therefore, the plasma processing gas can be flowed from the first electrode side toward the second electrode side. For this reason, the plasma processing gas can flow smoothly toward the substrate to be processed. In addition, since a plasma region is formed between the first electrode and the second electrode, a plasma processing gas can flow in this region. Therefore, since the distance that the plasma processing gas flows in the plasma region can be increased, the separation and dissociation of the plasma processing gas can be promoted.

  As described above, the plasma process apparatus according to the present invention includes a plasma generation unit that is provided at a position distant from the substrate to be processed and includes a plurality of plasma regions having different region areas. As a result, plasmas having different energies are generated in plasma regions having different area areas, so that different types of material gases can be given different energies. Therefore, there is an effect that different energy can be given according to the material gas. Therefore, it is possible to uniformly separate and dissociate the material gas, generate uniform radicals, efficiently use energy, and improve the plasma processing throughput.

  A plasma processing apparatus according to an embodiment of the present invention will be described below with reference to FIGS. In the following embodiments, a plasma CVD apparatus will be described as an example of the plasma process apparatus according to the present invention, but the present invention is not limited to this.

  First, the structure of the plasma CVD apparatus of this embodiment is demonstrated. FIG. 1 is a cross-sectional view showing a schematic configuration of a plasma processing apparatus according to an embodiment of the present invention. As shown in FIG. 1, the plasma CVD apparatus 60 deposits radicals R of a material gas G generated by plasma on a film forming substrate 2 placed in a vacuum vessel 50, thereby forming the surface of the film forming substrate 2. Is formed into a film.

  First, the configuration of the CVD apparatus 60 will be described. The plasma CVD apparatus 60 includes a film formation substrate (substrate to be processed) 2, a substrate holder 3 for placing (holding) the film formation substrate 2, a plasma generation unit 15, and a gas in a vacuum container (processing chamber) 50. And an introduction part 56.

  In addition, outside the vacuum vessel 50, a gas supply unit 54 that supplies a material gas (a gas for plasma processing) serving as a film forming material into the vacuum vessel 50, and a vacuum pump (in which the vacuum vessel 50 is evacuated) And an electric power supply unit 57 that supplies electric power (applies electrical energy) to the plasma generation unit 15 (more specifically, cathode electrodes 17a and 17b described later). The power supply unit 57 includes high-frequency power sources 52a and 52b that apply a voltage to the cathode electrodes 17a and 17b, and a switch S that switches between the high-frequency power sources 52a and 52b. The high-frequency power sources 52a and 52b are connected to the cathode electrodes 17a and 17b via an introduction terminal 51 provided on the vacuum vessel 50. The high frequency power sources 52a and 52b supply electrical energy for causing plasma discharge by applying a high frequency voltage to the plasma generator 15, and are supplied to the cathode electrodes 17a and 17b via the switch S and the introduction terminal 51. It is connected. The switch S is provided to switch the high-frequency power sources 52a and 52b applied to the cathode electrodes 17a and 17b.

  Here, the plasma generation part 15 which is the characteristic part of this invention is demonstrated based on FIGS. FIG. 2 is a cross-sectional view showing the main configuration of the CVD apparatus 60 near the cathode electrode 17. FIG. 3 is a perspective view showing a main part configuration in the vicinity of the cathode electrode 17 of the CVD apparatus 60. In FIG. 3, the configuration in the vicinity of the cathode electrode 17 is shown with the configuration in FIGS. 1 and 2 turned upside down (rotated 180 degrees).

  The plasma generation unit 15 is disposed in the vacuum container 50 so as to be separated from the film formation substrate 2 and to face the film formation substrate 2. And the plasma generation part 15 generate | occur | produces a plasma by the electric power supply from the electric power supply part 57 (high frequency power supply 52a * 52b).

  The plasma generating unit 15 includes an anode electrode (anode; second electrode) 13, cathode electrodes 17 a and 17 b (cathode; first electrode), an insulator 14, and an insulator 18.

  More specifically, the plasma generating unit 15 is provided with an insulator 14 between the cathode electrodes 17a and 17b, and an anode electrode 13 is provided at the tip of the insulator 14 (on the film formation substrate 2 side). Yes. For this reason, the anode electrode 13 is provided closer to the deposition substrate 2 than the cathode electrodes 17a and 17b. In particular, the cathode electrodes 17a and 17b are designed to have different distances from the anode electrode 13.

  Further, the cathode electrodes 17 a and 17 b and the insulator 14 are formed on the same surface of the insulator 18. In other words, the cathode electrode 17a, the insulator 14, and the cathode electrode 17b are formed on the bottom surface of the insulator 18 on the film formation substrate 2 side (the surface facing the film formation substrate 2). That is, the structure of the cathode electrode 17a, the insulator 14, the cathode electrode 17b, the insulator 14,... Is repeatedly formed. Further, the insulator 14 protrudes closer to the film formation substrate 2 than the cathode electrodes 17a and 17b. The side surface of the insulator 14 is substantially perpendicular to the surface of the cathode electrodes 17a and 17b facing the film formation substrate 2. An anode electrode 13 is provided at the tip of the insulator 14 on the side facing the film formation substrate 2. That is, as shown in FIG. 3, the anode electrodes 13 are provided in stripes along one direction (surface to be processed) of the surface directions of the film formation substrate 2. Thereby, the plasma discharge surface of the anode electrode 13, the plasma discharge surface of the cathode electrode 17a, the plasma discharge surface of the anode electrode 13, the plasma discharge surface of the cathode electrode 17b, etc. are repeatedly formed on the same plane side of the insulator 18. Has been. The plasma discharge surface will be described later.

  The anode electrode 13 and the cathode electrodes 17a and 17b, and the cathode electrode 17a and the cathode electrode 17b are electrically insulated from the anode electrode 13 by the insulator 14, respectively. In the present embodiment, alumina is used as the material of the insulator 14. Here, the insulator 14 and the insulator 18 are separate insulators, but may be integrated.

  The cathode electrodes 17 a and 17 b are formed on the insulator 18. That is, the cathode electrodes 17a and 17b are formed on the same plane. Gas inlets 11a and 11b are formed through the insulator 18 and the cathode electrodes 17a and 17b in the thickness direction at predetermined intervals. Thus, when gas is supplied from the gas supply unit 54 to the gas introduction unit 56 via the gas pipe (gas introduction path) 16, the gas once stays in the gas introduction unit 56, and then the gas introduction port 11 a. It is introduced into the vacuum vessel 50 through 11b.

  As described above, the plasma CVD apparatus is characterized in that the cathode electrodes 17a and 17b have two plasma regions 10a and 10b having different region areas because the cathode electrodes 17a and 17b are designed to have different distances from the anode electrode 13. For this reason, characteristics such as energy and magnitude of plasma generated in the plasma regions 10a and 10b are different.

  Next, plasma discharge in the plasma generator 15 will be described.

  The plasma generator 15 generates a discharge (plasma) according to a voltage (potential difference) applied between the anode electrode 13 and the cathode electrodes 17a and 17b. That is, the surfaces of the anode electrode 13 and the cathode electrodes 17a and 17b function as plasma discharge surfaces for discharging plasma. In other words, the region between the anode electrode 13 and the cathode electrodes 17a and 17b functions as plasma regions (plasma discharge parts) 10a and 10b.

  That is, the plasma regions 10a and 10b are regions surrounded by the plasma discharge surfaces of the anode electrode 13 and the cathode electrodes 17a and 17b. In the present embodiment, since the insulator 14 is present, a pair of adjacent insulators 14 and 14 adjacent to each other, the anode electrodes 13 and 13 formed at the tips of the insulators 14 and 14, and the cathode electrode 17a or 17b. The regions surrounded by are plasma regions 10a and 10b. In other words, on the insulator 18, the region of the cathode electrode 17a and the region of the cathode electrode 17b are provided with the insulator 14, and the cathode electrodes 17a and 17b are separated from each other by the insulator 14 and the insulator 18. It has a partitioned configuration. Such regions surrounded by the anode electrode 13 and the cathode electrodes 17a and 17b are plasma regions 10a and 10b (plasma discharge spaces (plasma discharge spaces)).

  More specifically, in the present embodiment, portions of the cathode electrodes 17a and 17b and the cathode electrode 13 that are visible from the film formation surface (surface to be processed) of the film formation substrate 2 function as the plasma surface of each electrode. That is, both the cathode electrodes 17 a and 17 b and the anode electrode 13 are configured by a surface (part) where the entire plasma discharge surface is visible from the normal direction of the film formation substrate 2. The plasma discharge surface means the surfaces of the cathode electrodes 17a and 17b and the anode electrode 13 that substantially function as discharge electrodes. That is, the plasma discharge surface is a surface that exchanges charges in the plasma regions 10a and 10b.

  Accordingly, in this embodiment, the surface of each electrode that is not in contact with the insulator 14 and the insulator 18 is the plasma discharge surface. On the other hand, contact surfaces of the anode electrode 13 with the insulator 14 (surfaces on the cathode electrodes 17 a and 17 b side) and contact surfaces of the cathode electrodes 17 a and 17 b with the insulator 14 and the insulator 18 are formed from the film formation substrate 2. The surface is not visible. Thus, the contact surfaces of the anode electrode 13 and the cathode electrodes 17a and 17b with the insulator 14 and the insulator 18 do not function as plasma discharge surfaces.

  When the anode electrode 13 and the cathode electrodes 17a and 17b are arranged at a predetermined interval and the insulator 14 is not provided between the electrodes, the surface of the anode electrode 13 on the cathode electrodes 17a and 17b side is provided. A portion where the cathode electrodes 17a and 17b and the anode electrode 13 overlap with each other when viewed from the normal direction of the film formation substrate 2 in the cathode electrodes 17a and 17b (surfaces facing the cathode electrodes 17a and 17b) ) To function as a plasma discharge surface. In this state, when a high frequency voltage is applied to the cathode electrodes 17a and 17b, the plasma discharge mainly occurs on the surfaces of the cathode electrodes 17a and 17b and the surface of the anode electrode 13 on the cathode electrode 17 side (deposition of the film formation substrate 2). Between the surface and the opposite surface). Therefore, most of the radicals R1 and R2 generated by the dissociation of the gases G1 and G2 by the plasma adhere as a thin film to the surface on the cathode electrode 17 side of the anode electrode 13, so that a thin film is formed on the surface of the film formation substrate 2. Can not be.

  In the present embodiment, since the anode electrode 13 is formed at the tip of the insulator 14 provided on the insulator 18, the anode electrode 13 and the cathode electrode 17 a are viewed from the normal direction of the film formation substrate 2.・ It is arranged so that it does not overlap 17b. That is, the plasma discharge surface of the anode electrode 13 and the plasma discharge surfaces of the cathode electrodes 17a and 17b are arranged so as not to face each other.

  Thus, in the plasma forming apparatus 60 of the present embodiment, the cathode electrodes 17 a and 17 b are alternately formed on the insulator 18. The cathode electrodes 17 a and 17 b are formed on the same plane of the insulator 18. Further, an insulator 14 is provided between the cathode electrode 17a and the cathode electrode 17b. That is, the cathode electrode 17a and the cathode electrode 17b are formed to face each other with the insulator 14 therebetween.

  An anode electrode 13 is formed at the tip of the insulator 14. In addition, gas inlets 11a and 11b are provided in a partial region of the stacked body of the insulator 18 and the cathode electrodes 17a and 17b so as to penetrate the stacked body.

  Here, the structure of the gas piping 16 and the gas introduction parts 11a and 11b will be described with reference to FIG. The configuration in FIG. 2 is a configuration in which two different types of material gases G1 and G2 are supplied from the gas supply unit 54 into the vacuum vessel 50 (not shown) from the gas inlets 11a and 11b. Specifically, in this configuration, two independent gas pipes 16a and 16b dedicated to the material gases G1 and G2 are provided. The gas pipes 16a and 16b communicate with the gas introduction ports 11a and 11b, respectively, so that the material gases G1 and G2 are guided to the plasma regions 10a and 10b.

  In this way, the two material gases G1 and G2 supplied from the gas supply unit 54 are introduced into the plasma region 10a of the cathode electrode 17a through the gas pipe 16a and the gas inlet 11a (the route of the material gas G1). And a path (the path of the material gas G2) that is introduced into the plasma region 10b of the cathode electrode 17b through the gas pipe 16b and the gas inlet 11b. Accordingly, different types of gases G1 and G2 can be reliably supplied to the plasma regions 10a and 10b having different region areas. Therefore, plasma energy can be given in accordance with the degree of separation / dissociation of the material gases G1 and G2.

Next, the configuration (shape) of the cathode electrode 17b will be described. As shown in FIG. 3, the cathode electrode 17b is disposed closer to the anode electrode 13 than the cathode electrode 17a. That is, when the distance between the cathode electrode 17a and the anode electrode 13 is d ₁ and the distance between the cathode electrode 17b and the anode electrode 13 is d ₂ , the relationship d ₁ > d ₂ is satisfied. The cathode electrode 17b is formed of an electrode portion 17d substantially the same as the cathode electrode 17a and a conductor portion 17c. That is, the cathode electrode 17a and the electrode portion 17d are provided on the insulator 18, and the insulator 14 is provided between the cathode electrode 17a and the electrode portion 17d. Furthermore, a conductor portion 17c is provided on the electrode portion 17d. The conductor portion 17c extends from the side surface of the insulator 14 along the direction of the anode electrode 13 (direction of the film formation substrate 2). In the configuration of FIG. 3, a triangular prism whose bottom surface is a right triangle is formed along the longitudinal direction in contact with the side surface of the insulator 14.

  Thus, the cathode electrode 17b functions as the cathode electrode 17b as a whole of the electrode portion 17d and the conductor portion 17c. That is, the cathode electrode 17b includes an electrode portion 17d to which electric energy is applied from the high frequency power sources 52a and 52b, and a conductor portion 17c that forms a sheath potential between the plasma and the electrode when the plasma discharge is actually performed. When attention is focused on one anode electrode 13, the distance between the anode electrode 13 and the cathode electrode 17a and the cathode electrode 17b (conductor portion 17c) on both sides thereof is different.

  The plasma generating unit 15 is disposed in the vacuum container 50 so as to be separated from the film forming substrate 2 and to face the film forming substrate 2. And the plasma generation part 15 generate | occur | produces a plasma by the electric power supply from the electric power supply part 57 (high frequency power supply 52a * 52b). That is, as shown in FIG. 2, in this embodiment, electrical energy (electric power) is supplied to the cathode electrodes 17a and 17b from the high-frequency power source 52a or 52 by switching the switches S (S1 to S4). It is like that.

  In the present embodiment, the cathode electrode 17b includes an electrode portion 17d and a conductor 17c. The conductor portion 17c is provided closer to the anode electrode 13 than the cathode electrode 17a. FIG. 4A is a cross-sectional view showing a main part configuration in the vicinity of the cathode electrodes 17 a and 17 b and the anode electrode 13. 1 to 3, the shape of the conductor 17c is the structure shown in FIG.

  That is, as shown in FIG. 4A, a conductor 17c having a semi-triangular cross section substantially perpendicular to the film formation substrate 2 is disposed on the electrode portion 17d on the electrode portion 17d in the plasma 10b region.

Here, the distance between the anode electrode 13 and the cathode electrode 17a (the distance between the anode electrode 13 and the cathode electrode 17a in the plasma region 10a) is d ₁ , and the distance between the anode electrode 13 and the cathode electrode 17b is d ₂ . At this time, the relationship of d ₁ > d ₂ is established. That is, by disposing the conductor 17c, the distance between the anode electrode 13 and the cathode electrode 17b can be reduced. Therefore, if the potential applied to the cathode electrode 17 is the same, the electric field strength of the plasma region 10b is larger than that of the plasma region 10a due to the relationship d ₁ > d ₂ . Therefore, the energy of the plasma region 10b can be increased compared to the plasma region 10a.

  Next, a method for forming a thin film on the film formation substrate 2 by the plasma CVD method using the plasma CVD apparatus 60 will be described below with reference to FIG.

  First, when a high frequency voltage is applied to the cathode electrodes 17a and 17b from the power sources 52a and 52b, an electric field is generated between the anode electrode 13 and the cathode electrodes 17a and 17b. Thereby, plasma is generated in the plasma regions 10a and 10b as glow discharge due to a dielectric breakdown phenomenon. Then, different gases G1 and G2 are supplied from the gas supply unit 54 to the plasma regions 10a and 10b through the gas inlets 11a and 11b. Thus, the gases G1 and G2 are decomposed by the electrons in the plasma regions 10a and 10b, and radicals R1 and R2 are generated. That is, the plasma regions 10a and 10b are spaces for generating radicals R1 and R2 of the gases G1 and G2.

  The generated radicals R1 and R2 diffuse toward the film formation substrate 2 and adhere to and deposit on the surface (surface to be processed) of the film formation substrate 2. Thereby, a film grows on the surface of the film formation substrate 2 to form a thin film. The thickness of the thin film is adjusted by controlling the power supply to the plasma generator 15.

  When radicals R1 and R2 are generated in the plasma regions 10a and 10b, a sheath potential is generated between the plasma regions 10a and 10b and the cathode electrode 17 due to electrons and charges in the plasma. As a result, the radicals R are diffused and deposited on the surface of the film formation substrate 2 to form a thin film.

  Thus, in this embodiment, when high frequency voltage is applied to the cathode electrodes 17a and 17b, plasma regions 10a and 10b that generate plasma are formed between the anode electrode 13 and the cathode electrodes 17a and 17b. Then, the gases G1 and G2 supplied to the plasma regions 10a and 10b are decomposed to generate radicals R1 and R2, thereby depositing and depositing the radicals R1 and R2 on the surface of the deposition substrate 2, thereby forming a film. A thin film can be formed on the surface of the substrate 2.

  Thus, in this embodiment, the film-forming substrate is not exposed to the plasma discharge space. That is, a plasma discharge space is formed at a position away from the film formation substrate. For this reason, ions accelerated in plasma do not collide with the surface of the thin film formed on the film formation substrate. Therefore, film quality deterioration of the thin film due to collision of ions in the plasma can be prevented.

  In addition, when a plurality of material gases are used during thin film formation, different energies can be given depending on the type of material gas, so that energy use efficiency is improved and uniform over the entire surface of the deposition substrate. A thin film having a thickness can be formed. Therefore, the expansion of the application range of thin film formation by the plasma processing apparatus of the present invention can be expected.

  Also, different types of gases with different decomposition efficiencies can be decomposed in plasma discharge spaces having different plasma energies. Therefore, the hydrogen concentration and NH bond concentration in the thin film formed on the film formation substrate can be easily adjusted, and the dielectric strength and the film formation rate can be improved. Therefore, it is possible to improve gas utilization efficiency and reduce energy loss.

  Further, the anode electrode and the cathode electrode are arranged on the same insulator via an insulator (dielectric) so that they do not overlap each other when viewed from the normal direction of the film formation substrate. It is possible to prevent a thin film from being formed on the surface facing the surface. Thus, radicals generated by decomposing the material gas can be efficiently guided onto the film formation substrate.

  As described above, in the present embodiment, the plasma generator 15 has a plurality of plasma regions 10a and 10b having different region areas. For this reason, plasmas having different energies are generated in the plasma regions 10a and 10b. For this reason, it is possible to give different energy to multiple types of material gas G1 * G2. That is, in this embodiment, since it has several plasma area | region 10a * 10b from which area | region area differs, it becomes possible to form a different electric field in the area | region 10a * 10b with the same power supply, for example. Thereby, different energy can be given according to the kind of material gas G1 * G2. As a result, the material gases G1 and G2 can be uniformly separated and dissociated to generate uniform radicals. Accordingly, it is possible to efficiently use energy and improve the throughput of plasma processing.

  In the present embodiment, the plasma generation unit 15 includes the cathode electrodes 17a and 17b that are insulated from each other, and the anode electrode 13 that is provided closer to the deposition substrate 2 than the cathode electrodes 17a and 17b. The cathode electrodes 17a and 17b have a plurality of cathode electrodes 17a, 17b,... That are insulated from each other and have different distances from the anode electrode 13.

  As a result, plasma regions 10 a and 10 b are formed between the cathode electrodes 17 a and 17 b and the anode electrode 13. That is, the plasma regions 10 a and 10 b are portions surrounded by the plasma discharge surface of the cathode electrode 17 a and the plasma discharge surface of the anode electrode 13. Accordingly, a plurality of plasma regions 10a and 10b having different region areas are formed by a plurality of types of cathode electrodes 17a and 17b having different distances from the anode electrode 13. As a result, plasmas having different energies are generated in accordance with the arrangement state of the cathode electrodes 17a and 17b with respect to the anode electrode 13, so that different energies can be given to a plurality of types of material gases G1 and G2. Thereby, different energy can be given according to material gas G1 * G2.

  In the present embodiment, the plasma discharge surfaces of the cathode electrodes 17 a and 17 b and the anode electrode 13 are portions that can be viewed from the surface to be processed of the film formation substrate 2.

  As a result, it is possible to prevent plasma from being generated on the surfaces of the cathode electrodes 17a and 17b and the anode electrode 13 opposite to the plasma discharge surfaces. That is, it is possible to prevent a thin film from being formed on the surfaces of the cathode electrodes 17a and 17b and the anode electrode 13 that are opposed to the plasma discharge surface. Therefore, radicals generated by decomposing the material gases G 1 and G 2 can be efficiently guided onto the film formation substrate 2.

  In the present embodiment, the anode electrode 13 is disposed on the insulator 14 provided between the cathode electrodes 17a and 17b.

  As a result, the cathode electrodes 17a and 17b and the anode electrode 13 are integrally formed through the insulator 14. Therefore, the configuration of the plasma generator 15 can be simplified.

  Further, since the cathode electrodes 17a and 17b and the anode electrode 13 are provided via the insulator 14, plasma is generated on the surfaces of the cathode electrodes 17a and 17b and the anode electrode 13 that are opposed to the plasma discharge surface. Can be prevented. That is, it is possible to prevent a thin film from being formed on the surfaces of the cathode electrodes 17a and 17b and the anode electrode 13 that are opposed to the plasma discharge surface. Therefore, radicals generated by decomposing the material gases G 1 and G 2 can be efficiently guided onto the film formation substrate 2.

  In the present embodiment, the cathode electrodes 17a and 17b are characterized by having a plasma discharge surface having a concave cross section. Thereby, since the area of the plasma discharge surface of the cathode electrodes 17a and 17b can be increased, it is possible to reduce the disappearance of plasma and radicals generated in the cathode electrodes 17a and 17b. Moreover, since the cross section is concave, a hollow cathode effect (an effect of obtaining high-density plasma) is also obtained.

In the present embodiment, the cathode electrodes 17a and 17b satisfy the distance d ₁ > d ₂ from the anode electrode 13, and the distance d _{2 to} the cathode electrode 17b of the distance d ₂ satisfies the distance d ₁ > d _2. and a electrical energy supply unit 57 for supplying a large electrical energy than the cathode electrode 17a of d _1.

Thus, it is possible to generate more plasma energy at the cathode electrode 17b of the distance d _2. Thus, dissociation of the gas at the cathode electrode 17b of the distance d ₂ (the production rate of the radicals) can be further improved.

  In the present embodiment, the electrical energy supply unit 57 can also supply the same electrical energy to the cathode electrodes 17a and 17b.

  Thereby, since it is not necessary to provide the electrical energy supply part of different electrical energy, the structure of the electrical energy supply part 57 can be simplified.

  Moreover, in this embodiment, it is preferable that electrical energy is selected from a frequency region of 100 kHz or more and 300 MHz or less.

  As a result, the cathode electrodes 17a and 17b can stably discharge, and the film thickness can be improved. It is also effective in increasing the degree of gas dissociation (radical generation rate) at the cathode electrodes 17a and 17b.

  Moreover, in this embodiment, the gas piping 16 (16a * 16b) which guides the material gas G1 * G2 to the plasma generation part 15 independently for every kind of material gas G1 * G2 is provided.

  Accordingly, different types of material gases G1 and G2 can be reliably supplied to the plurality of plasma regions 10a and 10b having different region areas. Therefore, plasma energy can be given in accordance with the degree of separation / dissociation of the material gases G1 and G2.

  In the present embodiment, the gas pipes 16 (16a and 16b) guide the material gases G1 and G2 to the cathode electrodes 17a and 17b.

  Thus, the material gases G1 and G2 supplied from the gas supply unit 54 are guided to the cathode electrodes 17a and 17b through the gas pipe 16. Since the anode electrode 13 is closer to the deposition substrate 2 side than the cathode electrodes 17a and 17b, the material gases G1 and G2 can flow from the cathode electrodes 17a and 17b toward the anode electrode 13 side. Therefore, the material gases G1 and G2 can flow smoothly toward the film formation substrate 2. Further, since the plasma regions 10a and 10b are formed between the cathode electrodes 17a and 17b and the anode electrode 13, the material gases G1 and G2 can flow in these regions. Accordingly, since the distance through which the material gases G1 and G2 flow in the plasma regions 10a and 10b can be increased, the separation and dissociation of the material gases G1 and G2 can be promoted.

  In the present embodiment, a region (a space having a concave cross section) surrounded by one cathode electrode 17a and a pair of insulators 14 and the anode electrode 13 facing each other with the cathode electrode 17a interposed therebetween. The plasma region 10a. The gas G1 is supplied from the gas supply unit 54 to the plasma region 10a via the gas inlet 10a. The gas G1 supplied to the plasma region 10a is separated and dissociated by plasma to generate radicals R1. Then, the radical R1 is deposited on the film formation substrate 2 to form a thin film. Thus, since the gas G1 is supplied from the gas supply unit 54 to the plasma region 10a, it can be said that the plasma region 10a is also a gas introduction region A. Similarly, since the gas G2 is supplied from the gas supply unit 54 to the plasma region 10b, it can be said that the plasma region 10b is also a gas introduction region B.

  As shown in FIG. 3, in this embodiment, plasma regions 10 a (gas introduction regions A) and plasma regions 10 b (gas introduction regions B) are alternately formed between adjacent insulators 14 and 14. .

  In the plasma region 10b (gas introduction region B), since the conductor 17c is disposed on the electrode portion 17d, the distance between the anode electrode 13 and the cathode electrode 17a is different from the distance between the anode electrode 13 and the cathode electrode 17b. That is, the area of the plasma region 10a (gas introduction region A) is different from that of the plasma region 10b (gas introduction region B). Therefore, when the same frequency and the same voltage are applied to the cathode electrodes 17a and 17b, the plasma energy generated in the plasma regions 10a and 10b differs. Thereby, different plasma energy can be given to gas G1 * G2 supplied to plasma area | region 10a * 10b.

  In the present embodiment, the gas pipes 16a and 16b communicate with the gas introduction regions A and B (plasma regions 10a and 10b) via the gas introduction ports 11a and 11b, respectively. That is, different types of gases G1 and G2 can be supplied from the gas supply unit 54 to the gas introduction regions A and B through the gas introduction ports 11a and 11b.

  In the present embodiment, since the anode electrode 13 is formed at the tip of the insulator 14 provided on the insulator 18, the anode electrode 13 and the cathode electrode 17 a are viewed from the normal direction of the film formation substrate 2.・ It is arranged so that it does not overlap 17b. That is, the plasma discharge surface of the anode electrode 13 and the plasma discharge surfaces of the cathode electrodes 17a and 17b are arranged so as not to face each other.

Thereby, since the surface of the anode electrode 13 on the cathode electrode 17 side is in contact with the insulator 14, the radical R generated by the decomposition of the gas G is attached as a thin film to the surface of the anode electrode 13 on the cathode electrode 17 side. In this embodiment, the cathode electrode 17b extends along the side surface of the insulator 14, and its cross section is concave. Yes. That is, the plasma discharge surface of the cathode electrode 17b is concave. As a result, the angle formed by the side surface of the insulator 14 (surface on which the cathode electrode 17b is formed) and the inclined surface of the cathode electrode 17b can be an obtuse angle (preferably 180 degrees). Accordingly, it is possible to reduce the disappearance of the plasma and radicals generated on the surface of the cathode electrode 17b by colliding with the insulator 14. Further, since the cross section is concave, a hollow cathode effect can be obtained.

  In the present embodiment, the gas introduction ports 11a and 11b are formed on the cathode electrodes 17a and 17b side. That is, the gas inlets 11a and 11b are formed farther from the film formation substrate 2 than the anode electrode. Thereby, material gas G1 * G2 can be introduce | transduced in the vacuum vessel 50 from cathode electrode 17a * 17b side. For this reason, the material gases G1 and G2 can flow smoothly toward the film formation substrate 2. Further, since the plasma regions 10a and 10b are formed between the cathode electrodes 17a and 17b and the anode electrode 13, the material gases G1 and G2 can flow in these regions. Accordingly, since the distance through which the material gases G1 and G2 flow in the plasma regions 10a and 10b can be increased, the separation and dissociation of the material gases G1 and G2 can be promoted.

  In the present embodiment, the cathode electrodes 17a and 17b can be connected to the power source 52a or 52b via the switches S (S1 to S4), respectively. Thus, since the power (voltage) and frequency applied to the cathode electrodes 17a and 17b can be controlled, the energy of the plasma regions 10a and 10b can be further controlled. Thereby, the plasma energy suitable for material gas can be given further. Therefore, the composition of the thin film formed on the film formation substrate 2 can be controlled more finely.

  In the present embodiment, the area of the plasma discharge surface of the cathode electrodes 17a and 17b is larger than the area of the discharge surface of the anode electrode 13. Thereby, the electric field of an anode sheath part can be enlarged. As a result, since the dissociation of the material gas at the anode sheath part is promoted in addition to the cathode sheath part, the degree of gas dissociation can be improved. Note that the degree of gas dissociation can be further improved by making the area of the plasma discharge surfaces of the cathode electrodes 17a and 17b larger than the area of the ground potential portion at the same ground potential as the anode electrode 13.

  Moreover, in this embodiment, material gas G1 * G2 is set according to the thin film to form. For example, in the case where a silicon nitride film is formed as in the embodiments described later, a silicon nitride film can be formed on the deposition substrate 2 by using monosilane gas as the gas G1 and ammonia gas as the gas G2.

  Ammonia gas has lower decomposition efficiency (gas decomposition efficiency when the same energy is applied) than monosilane gas. That is, ammonia gas has a higher degree of dissociation (energy required to decompose the gas) than monosilane gas. That is, when the same energy is applied, ammonia gas is less likely to decompose than monosilane gas. For this reason, in the structure which decomposes | disassembles multiple types of gas within the same plasma area | region like the conventional parallel plate type plasma CVD apparatus, ammonia gas cannot be decomposed | disassembled completely and the utilization efficiency of ammonia gas may fall. .

  On the other hand, in the present embodiment, the cathode electrodes 17a and 17b having different distances from the anode electrode 13 are provided. For this reason, the distance between the anode electrode 13 and the cathode electrode 17b is shorter than the distance between the anode electrode 13 and the cathode electrode 17a. Thereby, the electric field strength of the plasma region 10b can be increased as compared with the plasma region 10a. Therefore, the plasma region 10b is a region having higher energy than the plasma region 10a. That is, a lot of plasma can be generated in the plasma region 10b. Therefore, by decomposing the monosilane gas in the plasma region 10a and decomposing the ammonia gas in the plasma region 10b, the ammonia gas can be given higher energy than the monosilane gas. For this reason, it becomes possible to decompose efficiently ammonia gas which is harder to decompose than monosilane gas.

  In this way, when using a plurality of gases, a large electric field is applied to a gas that is relatively difficult to decompose, that is, a gas that is relatively difficult to decompose is supplied to a plasma region having a high plasma energy. Is preferred. That is, it is preferable to give larger electric energy (voltage or frequency) to a gas that is relatively difficult to decompose than a gas that is easily decomposed. Thereby, since it becomes possible to give energy required for the decomposition | disassembly according to the kind of gas, while using efficiency of gas improves, energy can also be used efficiently.

  In the present embodiment, the cathode electrodes 17 a and 17 b are formed on the insulator 18. That is, the back surface of the cathode electrode 17, that is, the surface facing the film formation substrate 2 is a contact surface with the insulator 18. In the absence of the insulator 18, plasma is also generated on this contact surface. If the insulator 18 is provided, the generated radical R can be prevented from adhering to the contact surface.

In this embodiment, the distances d ₁ and d ₂ between the cathode electrodes 17 a and 17 b from the anode electrode 13 satisfy d ₁ > d ₂ . More preferably, d ₁ > d ₂ > 5 mm. This is because when plasma is formed, portions called sheaths are formed in the vicinity of the cathode electrodes 17a and 17b, and they function as conductors like the electrodes, and the thickness of the sheath portion is about 5 mm.

The distance (d ₅ ) between the anode electrodes 13 is preferably such a distance that a plasma discharge space can be secured in the apparatus and is not affected by distribution spots. The distance _{d 5,} depending on the size of the device, for example, it is 10mm or more. However, if it is 30 mm or more, it is affected by distribution spots.

The distance d ₄ between the anode electrode 13 and the film formation substrate 2 is preferably such a distance that radicals generated in the plasma space can be uniformly diffused on the surface to be processed of the film formation substrate. The distance d ₄ is required to be at least 5 mm, and the distance d ₅ is preferably 15 mm or more in order to avoid the influence of distribution spots.

Note that the distribution spots are formed because radicals generated in the plasma space do not uniformly diffuse in the plane before reaching the film formation substrate. For example, the distance d ₄ is too close, the distance only radicals to diffuse is insufficient, the pattern of the anode electrode is formed.

  In the present embodiment, the cross-sectional shape of the conductor 17c is a right triangle, and the conductor 17c extends along (in contact with) the side surface of the insulator 14 and the electrode portion 17d. However, the cross-sectional shape of the conductor 17c is not particularly limited, and may be the shape shown in FIGS. 4B and 4C. FIG. 4B and FIG. 4C are cross-sectional views showing the main configuration in the vicinity of the cathode electrodes 17 a and 17 b and the anode electrode 13. 4 (b) and 4 (c) are the same as those in FIG. 4 (a) except that the shape of the conductor 17c is different. The distance from the anode electrode 13 is shorter than the distance from the cathode electrode 17a to the anode electrode 13.

  As shown in FIG. 4B, a conductor portion 17c having a rectangular cross section is disposed on the electrode portion 17d. That is, a rectangular column conductor portion 17c extending along the side surface of the insulator 14 is formed on the electrode portion 17d. Thereby, the distance between the anode electrode 13 and the cathode electrode 17b can be made smaller than the distance between the cathode electrode 13a.

In the case of FIG. 4B as well, as in the case of FIG. 4A, since the relationship d ₁ > d ₂ is established, if the voltage applied to the cathode electrode 17 is the same, the plasma region The electric field intensity in the plasma region 10b is larger than that in 10a. Therefore, larger plasma energy can be generated in the plasma region 10b.

  Further, as shown in FIG. 4C, a conductor 17c having a fan-shaped cross section (1/4 circle) is disposed on the electrode portion 17d. That is, a 1/4 cylindrical conductor portion 17c extending along the side surface of the insulator 14 is formed on the electrode portion 17d. Thereby, the distance between the anode electrode 13 and the cathode electrode 17b can be made smaller than the distance between the cathode electrode 13a.

In the case of FIG. 4C as well, as in the case of FIG. 4A, since the relationship of d ₁ > d ₂ is established, if the voltage applied to the cathode electrode 17 is the same, the plasma region The electric field intensity in the plasma region 10b is larger than that in 10a. Therefore, larger plasma energy can be generated in the plasma region 10b.

  As described above, the cross-sectional shape of the conductor 17c is shorter in the quarter circle shape than the triangular shape, and further in the rectangular shape rather than the quarter circle shape, the distance between the cathode electrode 17b and the anode electrode 13 is shortened. Therefore, the energy of the plasma 10b in the concave space B can be increased compared to the plasma 10a in the concave space A.

  Therefore, the energy of the plasmas 10a and 10b can be adjusted by setting the size, shape, material, and the like of the conductor 17c according to the decomposition efficiency of the gas used. This makes it possible to improve the gas utilization efficiency and the energy utilization efficiency.

  Further, in the present embodiment, the plasma regions 10a and 10b are alternately formed between the adjacent insulators 14, but the cathode electrode 17a in the insulator 18 depends on the type of gas used. The plasma discharge surfaces of the cathode electrodes 17a and 17b can be changed by changing the arrangement positions of the 17b and the anode electrode 13 or the shapes and widths of the cathode electrodes 17a and 17b and the anode electrode 13. That is, the ratio and positional relationship of the plasma regions 10a and 10b can be variously changed. Thereby, for example, it is possible to form a thin film having a desired film thickness or composition, such as formation of a thin film having a different film thickness or composition depending on the position of the film formation substrate 2.

  In the present embodiment, the conductor 17c that constitutes the cathode electrode 17b covers the entire surface of the electrode portion 17d. However, if the region of the plasma region 10a is not equal to the plasma region 10a, any configuration is possible. It may be. For example, the same effect can be obtained even when the conductor 17c is arbitrarily provided on the electrode portion 17d.

Moreover, in this embodiment, since it has plasma area | region 10a * 10b from which area | region area differs, the electric power and frequency of high frequency power supply 52a * 52b may be the same or different. When supplying the same power and the same frequency to the cathode electrodes 17a and 17b, any one of the high-frequency power sources 52a and 52b may be used. In the current plasma CVD apparatus, the frequency of 13.56 MHz is the mainstream. For this reason, for example, 13.56 MHz can be applied as the frequency of the high frequency power supplies 52a and 52b. Generally, when the frequency is increased, the radical generation density Gr, which is a precursor of film formation,
Gr = k (Te) × Ne × Ng
Given in. Here, k (Te) is a reaction constant for generating radicals, Ne is an electron density, and Ng is a raw material gas density. That is, an increase in the frequency of the high-frequency power supplies 52a and 52b is effective in increasing the radical generation rate. The frequency regions of the high-frequency power supplies 52a and 52b are preferably selected from regions of 100 kHz or more and 300 MHz or less, and moreover, in a plasma region having a relatively large region area (that is, the cathode electrode 17b close to the anode electrode 13). It is preferable to provide a large frequency. When a frequency of 13.56 MHz is applied, the discharge is stable and the film thickness uniformity is improved. Further, by giving a higher frequency to the plasma region (cathode electrode 17b) having a larger area, the radical generation rate (gas decomposition efficiency) due to the difference in the area of the region is increased, and the radical is also increased by the difference in frequency. The production rate is improved. Similar to the frequency, the same effect can be obtained by changing the power (voltage).

  In this embodiment, the gas pipe 16 is divided into two gas pipes 16a and 16b. However, the gas pipe is further divided into two or more types, and in addition to the conductor 17c, two or more types of conductors 17c. More types of plasma regions may be formed by disposing them on the electrode portions 17d. That is, a large number of plasma regions having different region areas may be formed. Thereby, it becomes possible to form a thin film made of more kinds of gas materials G. Further, the energy used and the composition can be controlled according to the type of the gas material G.

  In this embodiment, alumina is used as the material of the insulator 14, but other materials may be used as long as the electrodes can be insulated from each other.

In the present embodiment, as an example of a thin film, a case where a silicon nitride film is formed using ammonia gas and monosilane gas has been described as an example. However, the present invention is not limited to this, and other It can be applied to the formation of various thin films such as an amorphous silicon film, an n ⁺ silicon film, and a silicon oxide film. That is, as the material gases G1 and G2, in addition to ammonia gas and monosilane gas, a material gas capable of forming a target thin film can be applied by plasma treatment.

  In this embodiment, the film is formed by the plasma CVD method. However, the plasma processing apparatus of the present invention can be applied to the case where the thin film (resist) is etched by the dry etching method or the like. That is, in the plasma process apparatus of the present invention, as in the present embodiment, in addition to a plasma CVD apparatus (thin film forming apparatus) that forms a thin film on a substrate (film formation), for example, a material gas is used as an etching gas, Similar to the above plasma CVD apparatus, the present invention can also be applied to a dry etching apparatus for generating plasma and etching a thin film, and an asher apparatus for removing a resist.

  In the dry etching apparatus and the asher apparatus, the generation of plasma and the generation of radicals are the same mechanism as the plasma CVD apparatus. It is different from the plasma CVD apparatus. Moreover, what is necessary is just to apply gas suitable for each apparatus as material gas.

  In the present embodiment, as shown in FIG. 3, in the region of the cathode electrode 17 b, a conductor portion 17 c is provided inside each of the opposing insulators 14 and 14. However, the conductor portion 17c may be provided so that at least the area of the plasma region 10a of the cathode electrode 17a is different (so as not to be the same). For example, in FIG. 3, the conductor 17 c is provided inside each of the two adjacent opposing insulators 14, 14, but the conductor portion 17 c may be provided only on one insulator 14. Also in this case, since the area of the plasma region 10b is different from that of the plasma region 10b, the same effect can be obtained.

  In the present embodiment, the cathode electrode 17b is composed of an electrode portion 17d and a conductor portion 17c. For this reason, it is also possible to comprise the electrode part 17d and the cathode electrode 17a from the same member.

  In addition, the plasma process apparatus of this invention can also be expressed as the following 1st-16th plasma process apparatuses.

  In other words, the first plasma processing apparatus includes a processing chamber, a substrate holding unit on which the substrate to be processed is placed inside the processing chamber, and a plurality of discharges that are provided to face the substrate to be processed and generate plasma. A plasma process apparatus comprising a composite electrode having electrodes and a gas introduction port for supplying a material gas into the processing chamber, wherein at least two gas introduction regions are connected from the material gas supply unit to the gas introduction port. It is the structure isolate | separated into the above space.

  In the first plasma processing apparatus, the composite electrode includes a first electrode and a second electrode provided closer to the substrate to be processed than the first electrode, The first electrode and the second electrode have a configuration in which only a surface visible from the normal direction of the substrate to be processed functions as a plasma discharge space.

  In the third plasma processing apparatus and the second plasma processing apparatus, the first electrode is classified into a first a electrode (cathode electrode 17a) and a first b electrode (cathode electrode 17b) that do not conduct each other. In this configuration, different electrical energy sources and electrical energy sources are connected via switches.

  Further, the fourth plasma processing apparatus is the second plasma processing apparatus, wherein the second electrode is disposed on an insulator disposed between the first a electrode and the first b electrode.

  In addition, the fifth plasma processing apparatus is configured such that in the second plasma processing apparatus, the plasma discharge space has a concave shape surrounded by the first electrode, the insulator, and the second electrode.

  Further, the sixth plasma processing apparatus is the second plasma processing apparatus, wherein the conductor (conductor portion 17c) is not placed on the first electrode in the concave surface of the plasma space, and the plasma space (plasma region) A is added. The configuration is classified into a plasma space (plasma region) B.

  Further, the seventh plasma processing apparatus is configured such that, in the sixth plasma processing apparatus 6, the shape of the conductor on the first electrode is a rectangular shape, a semi-triangular shape, or a 1/4 circular shape.

  In addition, the eighth plasma processing apparatus is the second plasma processing apparatus, wherein the gas inlet is formed on the first electrode side forming a concave surface, and the gas inlet 11a on the first a electrode side and the first a It is the structure classified into the gas inlet 11b by the side of an electrode.

  Further, the ninth plasma process apparatus is the first plasma process apparatus or the second plasma process apparatus, wherein one of the gas pipes is a gas inlet 11a of the first a electrode, and the other gas pipe is a gas inlet of the first b electrode. 11b.

  Further, in the tenth plasma process apparatus, in any one of the first plasma process apparatus to the ninth plasma process apparatus, the electric energy supply source 52a has a frequency of 13.56 MHz or less, and the electric energy supply source 52b has a frequency Is a configuration having a frequency higher than 13.56 MHz.

  The eleventh plasma process apparatus may be configured such that in any one of the first plasma process apparatus to the tenth plasma process apparatus, the first a electrode is connected to the electric energy supply source 52a, and the first b electrode is connected to the electric energy supply source. 52B, a plasma space A and a plasma space B are formed by applying a voltage, a material gas is introduced from the gas introduction port 11a and the gas introduction port 11b, and the material gas is decomposed by a plasma CVD method. .

  In addition, the twelfth plasma process apparatus is the first plasma process apparatus to the eleventh plasma process apparatus, wherein the first a electrode is connected to the electric energy supply source 52b, and the first b electrode is connected to the electric energy supply source. The plasma space A and the plasma space B are formed by connecting to 52a and applying voltage, the material gas is introduced from the gas introduction port 11a and the gas introduction port 11b, and the material gas is decomposed by the plasma CVD method. .

  In the thirteenth plasma process apparatus, in any one of the first plasma process apparatus to the tenth plasma process apparatus, both the first a electrode and the first b electrode are connected to the electric energy supply source 52a or the electric energy supply source 52b. The plasma space A and the plasma space B are formed by connecting and applying voltage, the material gas is introduced from the gas introduction port 11a and the gas introduction port 11b, and the material gas is decomposed by the plasma CVD method.

  Further, in the fourteenth plasma process apparatus, in any one of the first plasma process apparatus to the tenth plasma process apparatus, both the first a electrode and the first b electrode are used as the electric energy supply source A or the electric energy supply source B. The plasma space A and the plasma space B are formed by connecting and applying voltage, the material gas is introduced from the gas introduction port 11a and the gas introduction port 11b, and the material gas is decomposed by the plasma CVD method.

  In the fifteenth plasma process apparatus, the electrical energy supply source 11a and the electrical energy supply source 11b have the same frequency in any of the first to ninth plasma process apparatuses.

  In addition, the sixteenth plasma process apparatus connects the first electrode a to the electrical energy supply source 52a in any one of the first plasma process apparatus to the ninth plasma process apparatus, and the fifteenth plasma process apparatus. The 1b electrode is connected to the electrical energy supply source 52b and different voltages are applied to form a plasma space A and a plasma space B, and a material gas is introduced from the gas introduction port 11a and the gas introduction port 11b. The material gas is decomposed by the CVD method.

  The present invention is not limited to the embodiment described above, and various modifications are possible within the scope shown in the claims, and the embodiment is obtained by appropriately combining the technical means disclosed in each. Is also included in the technical scope of the present invention.

  Next, five types of silicon nitride (SiNx) films were formed on the deposition substrate 2 by plasma CVD using the plasma CVD apparatus 60. Further, as a comparative example, a conventional parallel plate type plasma CVD apparatus (see FIG. 5) was used, and the film formation process was similarly performed.

In each example, monosilane gas (SiH ₄ ) and ammonia gas (NH ₃ ) were used as materials for the silicon nitride (SiNx) film.

In the plasma CVD apparatus 60, a load lock chamber (none of which is not shown) that is shut off from the vacuum container 50 by a gate valve is added to the vacuum container 50 in which the indoor pressure is maintained at 1 × 10 ⁻³ to 1 × 10 ⁻⁴ Pa. The film formation substrate 2 was transported to the substrate holder 3 via the route. And again, the inside of the vacuum vessel 50 was exhausted to 1 × 10 ⁻³ to 1 × 10 ⁻⁴ Pa by the vacuum pump 55.

  Next, ammonia gas (G1) and monosilane gas (G2) were supplied from the gas supply ports 54 to the plasma regions 10a and 10b from the gas inlets 11a and 11b, respectively. Then, high-frequency power is applied from the high-frequency power sources 52a and 52b connected to the cathode electrodes 17a and 17b, and plasma is generated in the plasma regions 10a and 10b by plasma discharge. Film formation was started.

After the film formation is completed, the plasma discharge is stopped, the gas in the vacuum vessel 50 is exhausted, the indoor pressure is returned to the state of 1 × 10 ⁻³ to 1 × 10 ⁻⁴ Pa, and the film is formed through the load lock chamber. The board | substrate 2 was carried out in air | atmosphere.

  In each example, a conductor 17c having a right triangle as shown in FIGS. 1 to 4A was used.

Further, the distance d ₁ between the anode electrode 13 and the cathode electrode 17a electrode is 10 mm, the distance d ₂ between the anode electrode 13 and the cathode electrode 17b is 5 mm, the distance d ₃ between the deposition substrate 2 and the cathode electrodes 17a and 17c is 30 mm, The distance d ₄ between the film formation substrate 2 and the anode electrode 13 was 20 mm, and the distance d ₅ between the anode electrodes 13 was 20 mm.

  The voltage of the high-frequency power supplies 52a and 52b was 200 W or 400 W, and the frequency was 13.56 MHz or 27.56 MHz.

  In each example, monosilane gas was introduced from the gas inlet 11a and decomposed with plasma in the plasma region 10a. Further, ammonia gas was introduced from the gas inlet 11b and decomposed by the plasma in the plasma region 10b. That is, the gas G1 is monosilane gas and the gas G2 is ammonia gas.

  As described above, the plasma region 10b generates a larger electric field than the plasma region 10b. Since the decomposition efficiency of the monosilane gas is higher than that of ammonia gas, the monosilane gas was decomposed by the plasma excitation method in the plasma region 10a by introducing the monosilane gas into the plasma region 10a from the gas introduction port 11a.

  In addition, since ammonia gas has a lower decomposition efficiency (higher dissociation) than silicon gas, there is a disadvantage that ammonia gas cannot be completely decomposed when decomposed under the same conditions as silicon gas. In order to make up for this drawback, in each embodiment, ammonia gas is introduced into the plasma region 10b from the gas introduction port 11b, so that it is decomposed by the plasma excitation method in the plasma region 10b. It was examined whether 10b can give higher energy.

Further, in the film forming process for performing the film forming process on the film forming substrate 2, a 5-inch silicon substrate is carried as the film forming substrate 2 from the load lock chamber to the substrate holder 3 of the vacuum vessel 50 through the gate valve, The vacuum pump 55 was evacuated to 1 × 10 ⁻³ to 1 × 10 ⁻⁴ Pa. The pressure during film formation was 200 Pa.

  Subsequently, while maintaining the gas pressure at 120 Pa, ammonia gas at a flow rate of 50 sccm is supplied from the gas supply unit 54 to the gas inlet 11b through the gas pipe 16b, and then monosilane gas at a flow rate of 10 sccm is supplied to the gas supply unit. From 54, the gas was supplied from the gas inlet 11b through the gas pipe 16a. “Sccm” is a gas flow rate in cubic centimeters flowing every minute at 0 ° C.

  Next, a high frequency voltage is supplied from the high frequency power source 52 to the cathode electrodes 17a and 17b, and plasma discharge between the anode electrodes 13 is utilized to dissociate the gases introduced from the gas introduction ports 11a and 11b. The film formation was started.

  In each embodiment, the voltage / frequency (electric energy) supplied to the cathode electrodes 17a and 17b and the connection state of the high-frequency power sources 52a and 52b are as follows.

[Example 1]
The cathode electrode 17a is connected to the high frequency power source 52a (frequency 13.56 MHz), the cathode electrode 17b is connected to the high frequency power source 52b (frequency 27.12 MHz), and the input power is 400 W for both power sources, A plasma region 10b was formed.

[Example 2]
The cathode electrode 17a is connected to the high frequency power source 52b (frequency 27.12 MHz), the cathode electrode 17b is connected to the high frequency power source 52a (frequency 13.56 MHz), and the input power is 400 W for both power sources. A plasma region 10b was formed.

Example 3
The cathode electrode 17a is connected to a high-frequency power source 52a (frequency 13.56 MHz), the cathode electrode 17b is connected to a high-frequency power source 52b (frequency 27.12 MHz), and the input power is 400 W for both power sources. And the plasma area | region 10b was formed.

Example 4
The cathode electrode 17a is connected to the high-frequency power source 52b (frequency 27.12 MHz), the cathode electrode 17b is connected to the high-frequency power source 52b (frequency 27.12 MHz), and the input power is 400 W for both power sources. And a plasma region 10b were formed.

Example 5
The cathode electrode 17a was connected to the high frequency power source 52a (frequency 27.12 MHz), the cathode electrode 17b was connected to the high frequency power source 52b (frequency 27.12 MHz), and the plasma region 10a and the plasma region 10b were formed. At this time, the input power to the cathode electrodes 17a and 17b was 200 W and 400 W, respectively.

[Comparative example]
Except for using the parallel plate type plasma CVD apparatus shown in FIG. 5, the film forming process was performed under the same conditions as in the example. The cathode electrode 117 was connected to the high frequency power source 152 (frequency 13.56 MHz), and the plasma region 110 was formed. At this time, the input power to the cathode electrode 17 was 400 W, respectively. Note that the distance between the film formation substrate 102 and the cathode electrode 117 and the distance between the cathode electrode 117 and the anode electrode 113 were both set to 30 mm.

[Evaluation of Examples and Comparative Examples]
Table 1 shows the result of comparing the silicon nitride films (SiNx films) formed by the respective examples and comparative examples.

  Table 1 shows the film formation rate, the withstand voltage, the hydrogen bond concentration in the film (the sum of the N—H bond and the Si—H bond), and the NH bond concentration in the film for the above Examples 1 to 5 and the comparative example. This is a summary of the evaluation results.

  The hydrogen bond concentration and the NH bond concentration were identified from the bond amount of silicon and hydrogen and the bond amount of nitrogen and hydrogen by Fourier transform infrared spectroscopy (FTIR). That is, a nitride film was deposited on a silicon substrate, irradiated with infrared laser light, and the interference waveform was subjected to Fourier transform processing, whereby the absorption of infrared light by the film was measured as a spectrum.

In addition, as for the withstand voltage, for example, a nitride film is deposited on a silicon substrate, and an electric field is applied up to 500 V in the film thickness direction. At this time, mercury is brought into contact with the film surface, and a voltage is applied through the mercury. The dielectric strength is defined as the dielectric strength when the electric current is 1 μA / cm ² when a voltage is applied.

  The film formation rate was calculated by dividing the film thickness of the nitride film formed on the silicon substrate by the film formation time.

  From the above evaluation results, there was no significant difference in the film formation rate even when Examples 1 to 5 were compared, but in each Example, the film formation rate was higher than that of the comparative example.

  In addition, when the withstand voltage is compared, it can be seen that the comparative example is remarkably low at 3.2 MV / cm as compared with Examples 1-5. In the comparative example, since the film formation substrate is exposed to the plasma region, it is considered that the thin film is greatly damaged by the collision of ions accelerated in the plasma. On the other hand, in each Example in which the film formation substrate 2 is not exposed to the plasma regions 10a and 10b, the withstand voltage shows a high value of 6.0 MV / cm or more.

Moreover, when the composition of the formed thin film is compared, in Examples 1 to 5, both the hydrogen concentration in the film and the NH bond concentration are higher than those in the comparative example. In Examples 1 to 5, the hydrogen concentration in the film related to the film quality improvement is higher than that of the comparative example and exceeds 7 × 10 ²¹ cm ⁻³ , which is said to provide relatively good characteristics. This is because, when the plasma regions 10a and 10b having different region areas are used, high plasma energy is generated in the plasma region 10b having a relatively large region area. That is, in the plasma region 10b, it is possible to dissociate the ammonia gas having a lower dissociation degree than the monosilane gas by applying plasma energy higher than that of the monosilane gas, and the dissociation of the ammonia gas is promoted.

  Thus, in each Example, the composition (film quality) of the thin film was improved as compared with the comparative example.

  The plasma process apparatus of the present invention can be used for manufacturing a thin film by a CVD method of a semiconductor film such as amorphous silicon or an insulating film in the electronic industry, and can be suitably used for an etching apparatus by dry etching.

It is sectional drawing which shows schematic structure of the plasma processing apparatus which concerns on one Embodiment of this invention. It is sectional drawing which shows the principal part structure of the plasma process apparatus of FIG. It is a figure which shows the principal part structure of the plasma process apparatus of FIG. 4 (a) to 4 (c) are cross-sectional views showing the main configuration of the vicinity of the cathode electrode and the anode electrode in the plasma process apparatus of FIG. It is sectional drawing which shows schematic structure of the conventional plasma CVD apparatus.

Explanation of symbols

2 Deposition substrate (substrate to be processed)
10a, 10b Plasma region 11a, 11b Gas inlet 13 Anode electrode (second electrode)
14 Insulator 15 Plasma generator 16, 16a, 16b Gas piping (gas introduction path)
17a cathode electrode (first electrode, the distance _{d 1} of the electrode)
17b cathode electrode (first electrode, the distance _{d 2} of the electrode)
18 Insulator 50 Vacuum container (processing chamber)
52a, 52b High-frequency power supply 54 Gas supply unit 57 Electrical energy supply unit (first energy supply unit, second energy supply unit)
G1, G2 Material gas (plasma processing gas)

Claims (10)

A processing chamber; a gas supply unit that supplies a plasma processing gas to the processing chamber; and a plasma generation unit that is provided at a position away from the substrate to be processed and generates plasma in the processing chamber. A plasma processing apparatus for performing plasma processing on a substrate to be processed,
The plasma processing apparatus, wherein the plasma generation unit has a plurality of plasma regions having different region areas. The plasma generation unit includes a first electrode that is insulated from each other, and a second electrode that is a counter electrode of the first electrode and is provided closer to the substrate to be processed than the first electrode.
The plasma processing apparatus according to claim 1, wherein the first electrode includes a plurality of electrodes that are insulated from each other and have different distances from the second electrode.   3. The plasma processing apparatus according to claim 2, wherein the plasma discharge surfaces of the first electrode and the second electrode are parts visible from the surface to be processed of the substrate to be processed.   The plasma processing apparatus according to claim 2, wherein the second electrode is disposed on an insulator provided between the first electrodes.   The plasma processing apparatus according to claim 2, wherein the first electrode has a plasma discharge surface having a concave cross section. In the first electrode, a plurality of electrodes satisfying the distance d ₁ > d ₂ from the second electrode is supplied with a larger electric energy than the electrode at the distance d _{1 to} the electrode at the distance d ₂ . The plasma processing apparatus according to claim 2, further comprising an energy supply unit.   The plasma processing apparatus according to claim 2, further comprising a second energy supply unit configured to supply the same electric energy to the first electrode.   The plasma process apparatus according to claim 6 or 7, wherein the electrical energy is selected from a frequency region of 100 kHz or more and 300 MHz or less.   The plasma processing apparatus according to claim 2, further comprising a gas introduction path that guides the plasma processing gas to the plasma generation unit independently for each type of the plasma processing gas. The plasma processing apparatus according to claim 9, wherein the gas introduction path guides the plasma processing gas to the first electrode side.

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