JP2005353636A - Plasma processing apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve utilization efficiency of radicals generating in a plasma area and the accuracy of plasma processing and to enhance utilization efficiency of energy required for plasma processing. <P>SOLUTION: The plasma processing apparatus is provided with a processing chamber wherein a substrate 4 to be processed, a gas inlet 6 to introduce a gas into the inside of the chamber, and a plasma discharge generator 15 to form a plasma area in an area away from the substrate 4 by generating plasma discharge within the chamber, and it is used to apply plasma processing to the substrate 4. The plasma discharge generator 15 is provided with an electrode structure to generate an electric field parallel to the substrate 4 uniformly in the plasma area. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention provides a plasma processing apparatus that forms a plasma region in a region separated from a substrate to be processed by a predetermined distance.

  Conventionally, as a film formation method by a chemical vapor deposition method (Chemical Vapor Deposition, CVD method), a plasma CVD method in which a material gas is generated by applying high-frequency or low-frequency power to activate the material gas, A thermal CVD method in which a material gas is thermally decomposed by thermal energy is known.

  In particular, since the plasma CVD method is excellent in its simplicity and operability, it can be used for the manufacture of electronic devices such as integrated circuits, liquid crystal displays, organic electroluminescence elements, and solar cells, and the formation of semiconductor films, insulating films, and the like. Etc. are suitably used.

  A general plasma process apparatus for performing plasma processing such as the plasma CVD method will be described with reference to FIG. FIG. 8 is a cross-sectional view schematically showing a so-called parallel plate type plasma processing apparatus (see, for example, Patent Document 1).

  The plasma processing apparatus 100 includes a processing chamber 105 that is a vacuum container, and a pair of electrodes 102a and 102b that are provided inside the processing chamber 105 and are opposed to each other while being electrically insulated from each other.

  The pair of electrodes 102a and 102b includes a cathode electrode 102a that is an electrode to which a voltage (electrical energy) is applied and an anode electrode 102b that is an electrode at a ground potential. The cathode electrode 102a and the anode electrode 102b are each formed of a conductive plate and arranged in parallel to each other.

  As shown in FIG. 8, the anode electrode 102 b is provided on a substrate holder 109 fixed to the bottom wall surface in the processing chamber 105, for example. On the substrate holder 109, the substrate to be processed 104, which is a target for film formation, is mounted via the anode electrode 102b. The substrate to be processed 104 is made of, for example, silicon or glass.

  On the other hand, the cathode electrode 102 a is fixed to the upper wall surface in the processing chamber 105 through a plate-like dielectric portion 117 and a chamber-like gas retention portion 107. A gas supply unit 113 provided outside the processing chamber 105 is connected to the gas retention unit 107. The cathode electrode 102 a and the dielectric portion 117 are formed with a gas inlet 106 for vertically introducing a material gas into the processing chamber 105 so as to penetrate vertically. Thus, the gas supplied from the gas supply unit 113 is introduced into the space region between the cathode electrode 102a and the anode electrode 102b through the gas retention unit 107 and the gas introduction port 106. Further, a gas exhaust unit 110 is connected to the processing chamber 105 so that the gas after the plasma processing is exhausted to the outside of the processing chamber 105.

  The cathode electrode 102a is connected to the high frequency power supply 101, while the anode electrode 102b is connected to the ground potential. The high frequency power supply 101 is configured to generate a high frequency voltage of 13.56 MHz, for example. Then, by applying a high frequency voltage between the cathode electrode 102a and the anode electrode 102b, an electric field is generated in the space region between the cathode electrode 102a and the anode electrode 102b, and a dielectric breakdown phenomenon between these electrodes 102a and 102b. As a result, plasma, which is a glow discharge phenomenon, is generated.

  With the above configuration, in the plasma processing apparatus 100, by introducing a material gas into the plasma region 111 formed in the processing chamber 105, the material gas is decomposed and dissociated in the plasma region 111 to generate radicals. The radicals generated in the plasma region 111 are diffused to the substrate to be processed 104 and deposited on the surface of the substrate to be processed 104 to form, for example, a semiconductor film or an insulating film.

  However, in the parallel plate type plasma processing apparatus, since the plasma region 111 is formed in the vicinity of the substrate to be processed 104, the substrate to be processed 104 is exposed to the plasma and can be bombarded with ions in the plasma. Unavoidable. As a result, the quality of the film formed on the substrate to be processed 104 may be deteriorated by the ion bombardment.

  Therefore, a so-called remote plasma processing apparatus is known in which the plasma region 111 is formed in a region separated from the substrate to be processed 104 by a predetermined distance (see, for example, Patent Document 2). Here, a general remote plasma processing apparatus 200 will be described with reference to FIG. 9 which is a schematic sectional view. The same parts as those in FIG. 8 are denoted by the same reference numerals, and detailed description thereof is omitted.

  The remote plasma process apparatus 200 is different from the parallel plate type plasma process apparatus 100 in that an anode electrode 102b is disposed between the substrate to be processed 104 and the cathode electrode 102a. That is, the anode electrode 102 b is not provided between the substrate to be processed 104 and the substrate holder 109. The anode electrode 102b is configured by a mesh-like conductive plate.

  Thus, the plasma region 111 is formed in a region that is separated from the substrate to be processed 104 by a predetermined distance and between the anode electrode 102b and the cathode electrode 102a. The radicals generated by the decomposition and dissociation of the material gas in the plasma region 111 pass through the mesh holes 122 of the anode electrode 102b and diffuse. As a result, the deposition process is performed by the deposition of radicals on the substrate 104 to be processed.

  Therefore, in the remote plasma processing apparatus 200, the plasma region 111 is separated from the substrate to be processed 104 by a predetermined distance, so that the substrate to be processed 104 during film formation is not easily affected by ions in the plasma. That is, the film quality can be improved.

  However, radicals generated in the plasma region 111 of the remote plasma processing apparatus 200 cannot pass through portions other than the mesh hole 122 on the surface of the anode electrode 102b. In other words, a part of radicals toward the substrate to be processed 104 is shielded by the anode electrode 102b.

  That is, in the remote plasma process apparatus 200, all of the generated radicals cannot be used for film formation, and there is a problem that the utilization efficiency of the material gas is lowered. Further, the pattern of the mesh hole 122 of the anode electrode 102b is projected as an unnecessary pattern on the film surface, which may cause deterioration in film quality.

  Therefore, instead of providing the mesh-like anode electrode 102b, the cathode electrode 102a and the anode electrode 102b are alternately arranged along the substrate surface of the substrate 104 to be processed as shown in FIG. Is known (see, for example, Patent Document 3).

  That is, in this remote plasma processing apparatus 300, the cathode electrode 102a and the anode electrode 102b are arranged in a stripe shape, and a gas inlet 106 is formed between the adjacent electrodes 102a and 102b. Thus, a plasma region 111 is formed between the cathode electrode 102a and the anode electrode 102b, and radicals generated in the plasma region 111 are deposited on the substrate 104 to be processed.

Therefore, according to the remote plasma process apparatus 300, since the mesh-like anode electrode 102b is not provided between the plasma region 111 and the substrate to be processed 104, the utilization efficiency of the material gas can be improved, and the film quality of the mesh pattern can be improved. It becomes possible to prevent deterioration.
JP-A-5-166728 JP-A-5-21393 JP-A-11-144892

  However, in the plasma process apparatus 300 of Patent Document 3, the distance between the cathode electrode 102 a and the anode electrode 102 b changes in the normal direction of the substrate 104 to be processed. Therefore, the intensity distribution of the electric field formed between the cathode electrode 102a and the anode electrode 102b changes in the normal direction of the substrate 104 to be processed.

  For example, in the electrode structure shown in FIG. 10, the interval between the adjacent cathode electrode 102a and anode electrode 102b is from the upper side to the lower side (that is, from the gas inlet 106 side to the substrate to be processed 104 side), Since it gradually increases, the electric field strength in the plasma region decreases from the top to the bottom.

  As a result, since the intensity distribution of the electric field in the plasma region 111 becomes non-uniform, the intensity distribution of the plasma generated in the plasma region 111 also becomes non-uniform. There is a problem that energy cannot be given. That is, in the plasma process apparatus 300 of Patent Document 3 described above, it is inevitable that the energy use efficiency required for plasma processing is reduced.

  The present invention has been made in view of these points, and the object of the present invention is to improve the efficiency of use of radicals generated in the plasma region and the accuracy of plasma processing, and the efficiency of use of energy required for plasma processing. Is to try to improve.

  In order to achieve the above object, a plasma processing apparatus according to the present invention includes a processing chamber in which a substrate to be processed is disposed, a gas inlet for introducing gas into the processing chamber, A plasma process apparatus for generating a plasma region in a region away from the substrate to be processed by generating a plasma discharge therein, and performing plasma processing on the substrate to be processed, wherein the plasma The discharge generator includes an electrode structure that uniformly generates an electric field in a direction parallel to the substrate to be processed in the plasma region.

  The plasma discharge generator includes an anode electrode in which a plurality of holes having a circular cross section extending in a normal direction of the substrate to be processed are formed, and a columnar cathode electrode provided at an axial center position of each hole, It is preferable to provide.

  The plasma discharge generator includes a cathode electrode in which a plurality of holes having a circular cross section extending in a normal direction of the substrate to be processed are formed, and a columnar anode electrode provided at an axial center position of each hole, It is good also as a structure provided with.

  It is preferable that the cathode electrode and the anode electrode are integrally formed through an insulating layer.

  The plasma discharge generator includes stripe-shaped anode electrodes and cathode electrodes that extend in a direction parallel to the substrate to be processed, and generates plasma discharge between the anode electrode and the cathode electrode. It may be configured as follows.

  It is preferable that an extension portion made of an insulating material is provided at an end portion of the anode electrode and the cathode electrode on the substrate to be processed side.

  The plasma processing apparatus according to the present invention generates a plasma discharge in a processing chamber in which a substrate to be processed is disposed, a gas introduction port for introducing a gas into the processing chamber, and the processing chamber. A plasma discharge generating unit for forming a plasma region in a region away from the substrate to be processed, and performing plasma processing on the substrate to be processed, wherein the plasma discharge generating unit includes: An electrode and a second electrode that is arranged in parallel to the substrate to be processed with respect to the first electrode and generates a plasma discharge between the first electrode and the first electrode. The distance between the two electrodes is defined to be a constant size in the normal direction of the substrate to be processed.

  The first electrode is an anode electrode in which a plurality of holes having a circular cross section extending in the normal direction of the substrate to be processed are formed, and the second electrode is provided at an axial center position of each hole. A columnar cathode electrode is preferred.

  The first electrode is a cathode electrode in which a plurality of holes having a circular cross section extending in the normal direction of the substrate to be processed are formed, and the second electrode is provided at an axial center position of each hole. It is good also as a structure which is a cylindrical anode electrode.

  It is preferable that the cathode electrode and the anode electrode are integrally formed through an insulating layer.

  The plasma discharge generator includes stripe-shaped anode electrodes and cathode electrodes that extend in a direction parallel to the substrate to be processed, and generates plasma discharge between the anode electrode and the cathode electrode. It may be configured as follows.

  It is preferable that an extension portion made of an insulating material is provided at an end portion of the anode electrode and the cathode electrode on the substrate to be processed side.

-Action-
Next, the operation of the present invention will be described.

  According to the plasma processing apparatus of the present invention, when plasma processing is performed on a substrate to be processed, the substrate to be processed is first placed inside the processing chamber. Thereafter, a gas is introduced into the processing chamber via a gas inlet, and a plasma discharge is generated from the plasma discharge generator. A plasma region where plasma discharge is generated is formed in a region away from the substrate to be processed. In the plasma region, the gas is decomposed and dissociated to generate radicals, and the radicals are subjected to plasma treatment by the radicals.

  At this time, since the plasma region is formed away from the substrate to be processed, ions in the plasma are difficult to reach the substrate to be processed. That is, since the substrate to be processed is not easily subjected to ion bombardment, it is possible to improve the accuracy of plasma processing on the substrate to be processed.

  Furthermore, when the plasma discharge generating part has an electrode structure that uniformly generates an electric field parallel to the substrate to be processed in the plasma region, the plasma discharge is uniformly generated in the plasma region. As a result, it is possible to uniformly apply plasma energy to the gas in the plasma region. Therefore, the utilization efficiency of energy required for plasma processing is improved.

  On the other hand, even when the plasma discharge generator has the first electrode and the second electrode, and the distance between the first electrode and the second electrode is constant over the normal direction of the substrate to be processed, the substrate to be processed is also provided. An electric field parallel to is uniformly generated in the plasma region. As a result, the plasma discharge is uniformly generated in the plasma region, so that the energy use efficiency required for the plasma treatment is improved as in the case described above.

  In addition, by forming one of the cathode electrode and the anode electrode into a hole having a circular cross section and the other as a cylindrical electrode provided at the axial center position of the hole, the distance between the cathode electrode and the anode electrode is It becomes uniform in the direction parallel to the substrate to be processed (that is, the radial direction of the hole). Therefore, an electric field in a direction parallel to the substrate to be processed is uniformly generated in the plasma region between the cathode electrode and the anode electrode. As a result, a uniform plasma discharge is generated in the plasma region in the same direction as the electric field. Further, even when the cathode electrode and the anode electrode are formed in a stripe shape, a uniform plasma discharge is generated in the plasma region between the cathode electrode and the anode electrode in a direction parallel to the substrate to be processed.

  Further, by providing an extension made of an insulating material at the end of the substrate to be processed with respect to the striped cathode electrode and the anode electrode, the end of each electrode is covered with the extension and the plasma discharge is performed. Does not occur. That is, since only the electrode surfaces of the electrodes facing each other contribute to the plasma discharge, the plasma discharge generated in the plasma region can be made more uniform.

  According to the present invention, since the plasma region is separated from the substrate to be processed, the accuracy of the plasma processing on the substrate to be processed can be improved. Further, since it is not necessary to provide a mesh electrode between the substrate to be processed and the plasma region as in the prior art, all radicals generated in the plasma region can be used for the plasma processing. In other words, radical utilization efficiency can be increased.

  Furthermore, since plasma discharge can be generated uniformly in the plasma region, plasma energy can be uniformly applied to the gas in the plasma region. That is, the utilization efficiency of energy required for plasma processing can be improved.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The present invention is not limited to the following embodiment.

Embodiment 1 of the Invention
1 to 3 show a plasma CVD apparatus 1 which is an embodiment of a plasma processing apparatus according to the present invention. FIG. 1 is a perspective view showing a part of the plasma CVD apparatus 1 in a cutaway view, and FIG. 2 is a cross-sectional view of the plasma CVD apparatus. FIG. 3 is a partially enlarged view of FIG.

  As shown in FIG. 2, the plasma CVD apparatus 1 includes a processing chamber (vacuum container) 5 in which a substrate 4 to be processed is disposed, and a gas introduction for introducing a gas (also referred to as a material gas) into the processing chamber 5. A port 6 and a plasma discharge generator 15 provided inside the processing chamber 5 are provided, and are configured to perform plasma processing on the substrate to be processed.

  The substrate to be processed 4 is made of, for example, silicon or glass. Typically, as shown in FIG. 2, a substrate holder 9 is fixed to the bottom wall surface inside the processing chamber 5. The substrate 4 to be processed is mounted on the substrate holder 9.

  The plasma discharge generation unit 15 is configured to form a plasma region 11 in a region away from the substrate 4 to be processed inside the processing chamber 5 by generating plasma discharge. The plasma discharge generating unit 15 is fixed to the upper wall surface in the processing chamber 5 via the plate-like dielectric layer 17 and the chamber-like gas retaining portion 7. A gas supply unit 13 provided outside the processing chamber 5 is connected to the gas retention unit 7.

  Further, the processing chamber 5 is provided with a gas discharge unit 10 for discharging the gas inside the processing chamber 5. For example, a mechanical booster pump or a rotary pump is preferably used as the gas discharge unit 10.

  Here, the structure of the plasma discharge generator 15 will be described in detail. As shown in FIG. 3, the plasma discharge generator 15 has an electrode structure that uniformly generates an electric field E in a direction parallel to the substrate 4 to be processed in the plasma region 11. That is, as shown in FIG. 1 and FIG. 2, the plasma discharge generator 15 includes a cathode electrode 2a that is a first electrode, an anode electrode 2b that is a second electrode, and a cathode electrode 2a and an anode electrode 2b. The insulating layer 16 (or dielectric layer) interposed is interposed. The insulating layer 16 is made of alumina, for example.

  The cathode electrode 2a is connected to a high frequency power supply 31, while the anode electrode 2b is connected to a ground potential. The high frequency power supply 31 is configured to generate a high frequency voltage of 13.56 MHz, for example. Then, by applying a high frequency voltage between the cathode electrode 2a and the cathode electrode 2b, an electric field E is generated in the space region (plasma region 11) between the cathode electrode 2a and the anode electrode 2b, and each of these electrodes 2a , 2b generates plasma which is a glow discharge phenomenon.

  That is, as shown in FIG. 1, the anode electrode 2b is formed of a conductive plate, and the front surface of the insulating layer 16 (hereinafter, the upper side in FIG. 1 and the lower side in FIGS. 2 and 3 are referred to as “front side”. The lower side in FIG. 1 and the upper side in FIGS. 2 and 3 are “rear side”. A plurality of holes 20 having a circular cross section extending in the normal direction of the substrate 4 to be processed are formed in the anode electrode 2 b and the insulating layer 16. The holes 20 are arranged in a matrix when viewed from the normal direction of the substrate 4 to be processed, and are formed so as to penetrate the anode electrode 2b and the insulating layer 16 in the front-rear direction.

  As shown in FIG. 1, the cathode electrode 2a is composed of a plate-shaped flat plate portion 21 laminated on the rear surface of the insulating layer 16, and a columnar protruding portion 22 protruding from the flat plate portion 21 and extending to the front side. Yes. The protrusions 22 are provided at the axial center positions of the respective holes 20. The length of the protrusion 22 is the same as the length of the hole 20 (that is, the thickness in the stacking direction of the anode electrode 2b and the insulating layer 16). Thus, the cathode electrode 2a and the anode electrode 2b are integrally formed via the insulating layer 16 to constitute the plasma discharge generator 15.

  In other words, as shown in FIG. 2, the plasma discharge generator 15 is provided in parallel with the cathode electrode 2a and in the direction parallel to the substrate 4 to be processed with respect to the cathode electrode 2a. And an anode electrode 2b for generating discharge.

  That is, the cathode electrodes 2a and the anode electrodes 2b are provided alternately at equal intervals as shown in FIG. The distance between the outer peripheral surface of the protruding portion 22 and the inner peripheral surface of the hole portion 20 is a constant size over the axial direction of the hole portion 20. In other words, the distance between the cathode electrode 2 a and the anode electrode 2 b is defined to be a constant size over the normal direction of the substrate 4 to be processed. As a result, the distance between the cathode electrode 2a and the anode electrode 2b is maintained at a constant distance inside the hole portion 20, so that the electric field E in the radial direction of the hole portion 20 is uniformly generated. .

  Further, as shown in FIG. 3, the distance between the plasma discharge generator 15 and the substrate to be processed 4 (that is, the distance between the cathode electrode 2a or the anode electrode 2b and the substrate to be processed 4) is D1, and the adjacent cathode electrode 2a. The distance between the anode electrode 2b and the anode electrode 2b is D2, the height of the anode electrode 2b is D3, and the height of the insulating layer 16 is D4. At this time, the distance D1 is larger than the distance D2 (D1> D2). Furthermore, the distance D4 is larger than the distance D2 (D4> D2).

  Assuming that D1 ≦ D2 and D4 ≦ D2, plasma discharge occurs between the tip of the protrusion 22 of the cathode electrode 2a and the substrate 4 to be processed, so that the substrate 4 to be processed is exposed to the plasma space. And may be damaged by ion bombardment. Therefore, as described above, each distance preferably satisfies the relationship of D1> D2 and D4> D2. The distance D3 is not particularly limited, but by defining D3 to be large, the plasma region 11 can be expanded to promote dissociation of the material gas.

  In the flat plate portion 21 of the cathode electrode 2a, a gas inlet 6 is formed around the proximal end portion of the protruding portion 22, as shown in FIG. For example, two gas inlets 6 are formed for each of the flat plate portions 21 constituting the bottom of the hole portion 20. The gas inlet 6 is formed through the flat plate portion 21 and the dielectric layer 17 in the front-rear direction, and communicates the plasma region 11 between the cathode electrode 2 a and the anode electrode 2 b and the gas retention portion 7. It is like that.

  The dielectric layer 17 is made of alumina or the like and is provided to prevent the occurrence of plasma discharge on the rear side of the cathode electrode 2a. That is, if the dielectric layer 17 is not provided, a plasma discharge is generated on the rear side of the cathode electrode 2 a, so that the material gas is decomposed before reaching the plasma region 11. Therefore, by providing the dielectric layer 17, the material gas can be reliably decomposed in the plasma region 11.

  In this way, the gas supplied from the gas supply unit 13 is temporarily retained in the gas retention unit 7 and then introduced into the plasma region 11 through the gas introduction port 6.

  Further, as shown in FIG. 4, the plurality of holes 20 may be arranged in a staggered manner. As a result, the holes 20 can be formed at a high density in the plasma discharge generator 15, so that the amount of decomposition of the material gas can be increased and the plasma processing speed can be improved. Further, as shown in FIG. 4, for example, four gas inlets 6 may be formed in each hole 20. Thereby, the decomposition efficiency of the material gas can be increased.

-Film formation method-
Next, a method for performing a film forming process on the substrate 4 to be processed by the plasma CVD apparatus 1 of the present embodiment will be described.

The inside of the processing chamber 5 is usually depressurized to a pressure of about 1 × 10 ⁻³ to 1 × 10 ⁻⁴ Pa, for example. The substrate 4 to be processed is loaded into the processing chamber 5 via a load lock chamber (not shown) blocked by, for example, a gate valve. The substrate 4 to be processed is transferred onto the substrate holder 9 and attached to the substrate holder 9. Then, the gas discharge part 10 is driven and the inside of the processing chamber 5 is again brought to a pressure of about 1 × 10 ⁻³ to 1 × 10 ⁻⁴ Pa.

  Thereafter, the gas supply unit 13 is driven to introduce the material gas into the processing chamber 5, and the high frequency power supply 31 is driven to form the plasma region 11 in the processing chamber 5. The plasma region 11 is formed at a predetermined distance D1 from the substrate 4 to be processed.

  The material gas is once supplied from the gas supply unit 13 to the gas retention unit 7, and then flows out from each gas introduction port 6 into the hole 20 of the plasma discharge generation unit 15. At this time, since the plasma region 11 is formed in the hole 20, the material gas is decomposed and dissociated in the plasma region 11 to generate radicals. Film formation is performed by depositing the radicals on the substrate 4 to be processed.

After the film formation is finished, the driving of the gas supply unit 13 and the high frequency power supply 31 is stopped. Subsequently, the gas discharge unit 10 is driven to exhaust the gas in the processing chamber 5. Thereafter, the internal pressure of the processing chamber 5 is returned to about 1 × 10 ⁻³ to 1 × 10 ⁻⁴ Pa again, and the substrate 4 to be processed is carried out to the outside through the gate valve and the load lock chamber. To do. Thus, the film forming process is completed.

(Example)
Next, an example in which a film forming process of a silicon nitride film (SiNx) is actually performed by the plasma CVD apparatus 1 of the present embodiment will be described together with a comparative example. In this example, the film was formed by the plasma CVD apparatus 1 shown in FIG.

  A 5-inch silicon substrate is applied to the substrate 4 to be processed, and ammonia gas at a flow rate of 50 sccm is supplied from the gas supply unit 13 into the processing chamber 5 while maintaining the pressure in the processing chamber 5 at 120 Pa. Subsequently, monosilane gas having a flow rate of 10 sccm is introduced into the processing chamber 5 from the gas supply unit 13.

  Further, the high frequency power supply 31 is driven to generate plasma discharge in the plasma region 11 as described above. At this time, the distance D1 between the plasma discharge generator 15 and the substrate 4 to be processed was 20 mm, and the distance D2 between the adjacent cathode electrode 2a and anode electrode 2b was 10 mm. Furthermore, the height D3 of the anode electrode 2b was 20 mm, and the height D4 of the insulating layer 16 was 15 mm.

  The evaluation results of the film formed under the above conditions are shown in the upper part of Table 1.

There were three evaluation items: film forming speed, withstand voltage, and film thickness distribution. Here, the deposition rate was calculated by dividing the thickness of the nitride film formed on the silicon substrate by the time required for deposition. The breakdown voltage is defined as follows. That is, for example, a nitride film is deposited on a silicon substrate, and a voltage of up to 500 V is applied in the thickness direction of the film. At this time, a voltage is applied through mercury brought into contact with the film surface. A voltage when the current becomes 1 μA / cm ² is defined as a withstand voltage. The film thickness distribution is defined as the ratio of the maximum value and the minimum value to the average value of the in-plane film thickness of the film formation substrate.

  In this example, the film formation rate was 62.8 nm / min, the withstand voltage was 7.21 MV / cm, and the film thickness distribution was ± 2.9%.

  Next, as Comparative Example 1, a film forming experiment using a parallel plate type plasma CVD apparatus as shown in FIG. Each condition such as gas type and pressure was the same as in the above example. However, the distance between the cathode electrode 102a and the anode electrode 102b was 30 mm. The evaluation result of the film formed under these conditions is shown in the middle of Table 1.

  In Comparative Example 1, the film formation rate was 62.5 nm / min, the withstand voltage was 4.43 MV / cm, and the film thickness distribution was ± 1.9%.

  Next, as Comparative Example 2, a film forming experiment using a remote plasma CVD apparatus as shown in FIG. Each condition such as gas type and pressure was the same as in the above example. However, the distance between the cathode electrode 102a and the anode electrode 102b was 20 mm, and the distance between the anode electrode 102b and the substrate to be processed 104 was 20 mm. That is, the anode electrode 102 b is disposed at an intermediate position between the cathode electrode 102 a and the substrate to be processed 104. The evaluation result of the film formed under these conditions is shown in the lower part of Table 1.

  In Comparative Example 2, the film formation rate was 56.1 nm / min, the withstand voltage was 7.18 MV / cm, and the film thickness distribution was ± 7.2%.

  From Table 1, it can be confirmed that the film forming rate was almost the same as that of Comparative Example 1, but larger than that of Comparative Example 2. This is because, unlike the comparative example 2, the example has no obstacle (such as an anode electrode) in the gas flow path from the gas inlet to the substrate to be processed, so that radicals can efficiently reach the substrate to be processed. It is.

  With respect to the withstand voltage, the comparative example 1 is remarkably low, and the example and comparative example 2 show a high value of 7.0 MV / cm or more. This is because the substrate to be processed is exposed to the plasma space in the parallel plate structure of Comparative Example 1 and the film surface is damaged by ion bombardment, but these effects can be avoided in the remote plasma structure.

  Regarding the film thickness distribution, Examples and Comparative Example 1 were within ± 3%, but those of Example 3 were 7% or more. This is because the plasma product locally changes and the film thickness is reduced by the deposition of radical products on the anode electrode. On the other hand, in the example, since these factors are not present, the film thickness distribution is slightly higher than that of the parallel plate electrode, but is within 3%.

  Therefore, according to the first embodiment, since the plasma region 11 is formed away from the substrate 4 to be processed, ions in the plasma are difficult to reach the substrate 4 to be processed. In other words, since the substrate to be processed 4 is less susceptible to ion bombardment, the accuracy of the plasma processing on the substrate to be processed 4 can be improved. Furthermore, since no member that obstructs the flow of the material gas is provided in the plasma region 11, radicals generated in the plasma region can be used for plasma processing such as film formation without waste. That is, the utilization efficiency of radicals generated in the plasma region can be increased.

  In addition, since the plasma discharge generating unit 15 has an electrode structure that uniformly generates the electric field E parallel to the substrate 4 to be processed in the plasma region 11, the plasma discharge is uniformly generated in the plasma region 11. be able to. As a result, since it is possible to uniformly apply plasma energy to the material gas in the plasma region 11, it is possible to improve the utilization efficiency of energy required for plasma processing.

  Particularly, since the hole 20 having a circular cross section is formed in the anode electrode 2b and the columnar cathode electrode 2a is provided at the axial center of the hole 20, the distance between the cathode electrode 2a and the anode electrode 2b is set as follows. It can be made uniform in the direction parallel to the substrate 4 (that is, the radial direction of the hole 20). Thereby, the electric field E in the direction parallel to the substrate to be processed 4 can be uniformly generated in the plasma region 11 between the cathode electrode 2a and the anode electrode 2b. As a result, a uniform plasma discharge can be generated in the same direction as the electric field.

<< Embodiment 2 of the Invention >>
5 and 6 show a plasma CVD apparatus 1 which is an embodiment of a plasma process apparatus according to the present invention. The same parts as those in FIG. 2 are denoted by the same reference numerals, and detailed description thereof is omitted.

  In this embodiment, the plasma discharge generator 15 includes anode electrodes 2b and cathode electrodes 2a that extend in stripes in a direction parallel to the substrate 4 and are alternately arranged.

  That is, as shown in FIG. 6 which is a plan view, the cathode electrode 2a and the anode electrode 2b are provided on the front surface of the dielectric layer 17 arranged in parallel to the substrate 4 to be processed, and are respectively comb-like electrodes. It is comprised by. And the comb-tooth part of the cathode electrode 2a and the comb-tooth part of the anode electrode 2b are arrange | positioned so that it may be combined and arranged in equal intervals. Thus, a plasma discharge is generated between the anode electrode 2b and the cathode electrode 2a.

  Also in the present embodiment, as in the first embodiment, the distance between the cathode electrode 2a and the anode electrode 2b is defined to be constant over the normal direction of the substrate 4 to be processed. That is, as shown in FIG. 5, the side surfaces of the cathode electrode 2a and the anode electrode 2b are formed in parallel to the normal direction of the substrate 4 to be processed. Furthermore, the side surface of the cathode electrode 2a is parallel to the side surface of the anode electrode 2b facing the side surface.

  As a result, the electric field E in the direction parallel to the substrate to be processed 4 is uniformly generated in the plasma region between each cathode electrode 2a and anode electrode 2b. Then, a plasma discharge is generated in the direction of the electric field E.

  Moreover, as shown in FIG. 7, it is preferable to provide the extension part 50 comprised with the insulating material in the edge part (namely, front side edge part) by the side of the to-be-processed substrate 4 in the anode electrode 2b and the cathode electrode 2a.

  That is, the side surfaces of the cathode electrode 2a and the anode electrode 2b are extended to the substrate 4 side (that is, the front side) by the side surfaces of the extension portion 50. As a result, the end surfaces of the cathode electrode 2a and the anode electrode 2b on the substrate 4 side to be processed are covered with the extension 50, so that it is possible not to contribute to the generation of plasma discharge. That is, since only the electrode surfaces (plasma discharge surfaces) facing each other of the cathode electrode 2a and the anode electrode 2b contribute to the plasma discharge, the plasma discharge generated in the plasma region 11 can be made more uniform.

<< Other Embodiments >>
In the first embodiment, the anode electrode 2b is an electrode having a plurality of holes 20, while the cathode electrode 2a is a cylindrical electrode provided at the axial center of the hole 20. It is not limited to. That is, the polarity of each electrode is reversed so that the cathode electrode 2a is an electrode having a plurality of holes 20, while the anode electrode 2b is a cylindrical electrode. Also by this, the same effect as the first embodiment can be obtained.

  In the first embodiment, the anode electrode 2b having a plurality of holes 20 and the end (front end) on the substrate 4 side of the cylindrical cathode electrode 2a are the same as those in the second embodiment. You may make it provide the extended part. This makes it possible to further uniformize the plasma discharge distribution on the front end portions of the cathode electrode 2a and the anode electrode 2b.

  As described above, the present invention is useful for a plasma processing apparatus that forms a plasma region in a region that is a predetermined distance away from the substrate to be processed. In particular, the utilization efficiency of radicals generated in the plasma region and the accuracy of plasma processing It is suitable for improving the utilization efficiency of energy required for plasma processing.

It is a perspective view which shows the plasma discharge generation | occurrence | production part of the plasma CVD apparatus of Embodiment 1. It is sectional drawing which shows the plasma CVD apparatus of Embodiment 1 typically. It is sectional drawing which expands and shows a plasma discharge generation | occurrence | production part. It is a top view which shows the other example of a plasma discharge generation part. It is sectional drawing which shows the plasma CVD apparatus of Embodiment 2 typically. It is a top view which shows a plasma discharge generation | occurrence | production part. It is sectional drawing which shows the other example of a plasma discharge generation part. It is sectional drawing which shows the conventional parallel plate type plasma process apparatus. It is sectional drawing which shows the conventional remote plasma process apparatus. It is sectional drawing which expands and shows the other example of the conventional remote plasma process apparatus.

Explanation of symbols

E Electric field 1 Plasma CVD equipment (plasma process equipment)
2a Cathode electrode (first electrode)
2b Anode electrode (second electrode)
4 Substrate 5 Process chamber 6 Gas inlet 11 Plasma region 15 Plasma discharge generating part 16 Insulating layer 20 Hole 50 Extension part

Claims (12)

A processing chamber in which a substrate to be processed is disposed;
A gas inlet for introducing gas into the processing chamber;
A plasma discharge generator that forms a plasma region in a region away from the substrate to be processed by generating a plasma discharge in the processing chamber;
A plasma processing apparatus for performing plasma processing on the substrate to be processed,
The plasma processing apparatus according to claim 1, wherein the plasma discharge generator includes an electrode structure that uniformly generates an electric field in a direction parallel to the substrate to be processed in the plasma region. In claim 1,
The plasma discharge generator includes an anode electrode having a plurality of holes with a circular cross section extending in the normal direction of the substrate to be processed, and a columnar cathode electrode provided at an axial center position of each hole, A plasma processing apparatus comprising: In claim 1,
The plasma discharge generator includes a cathode electrode in which a plurality of holes having a circular cross section extending in a normal direction of the substrate to be processed are formed, and a cylindrical anode electrode provided at an axial center position of each hole, A plasma processing apparatus comprising: In claim 2 or 3,
The plasma processing apparatus, wherein the cathode electrode and the anode electrode are integrally formed through an insulating layer. In claim 1,
The plasma discharge generation unit includes an anode electrode and a cathode electrode which are alternately arranged and extend in a stripe shape in a direction parallel to the substrate to be processed.
A plasma processing apparatus configured to generate plasma discharge between the anode electrode and the cathode electrode. In claim 5,
A plasma processing apparatus, wherein an extension portion made of an insulating material is provided at an end portion of the anode electrode and the cathode electrode on the substrate to be processed side. A processing chamber in which a substrate to be processed is disposed;
A gas inlet for introducing gas into the processing chamber;
A plasma discharge generator that forms a plasma region in a region away from the substrate to be processed by generating a plasma discharge in the processing chamber;
A plasma processing apparatus for performing plasma processing on the substrate to be processed,
The plasma discharge generation unit is provided in a direction parallel to the substrate to be processed with respect to the first electrode, and a second electrode that generates plasma discharge between the first electrode and the first electrode. With
The plasma process apparatus according to claim 1, wherein a distance between the first electrode and the second electrode is defined to be constant over a normal direction of the substrate to be processed. In claim 7,
The first electrode is an anode electrode in which a plurality of holes having a circular cross section extending in the normal direction of the substrate to be processed are formed,
The plasma processing apparatus, wherein the second electrode is a columnar cathode electrode provided at an axial center position of each hole. In claim 7,
The first electrode is a cathode electrode in which a plurality of holes having a circular cross section extending in the normal direction of the substrate to be processed are formed.
The plasma processing apparatus, wherein the second electrode is a cylindrical anode electrode provided at an axial center position of each hole. In claim 8 or 9,
The plasma processing apparatus, wherein the cathode electrode and the anode electrode are integrally formed through an insulating layer. In claim 7,
The plasma discharge generation unit includes an anode electrode and a cathode electrode which are alternately arranged and extend in a stripe shape in a direction parallel to the substrate to be processed.
A plasma processing apparatus configured to generate plasma discharge between the anode electrode and the cathode electrode. In claim 11,
A plasma processing apparatus, wherein an extension portion made of an insulating material is provided at an end portion of the anode electrode and the cathode electrode on the substrate to be processed side.

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