JP2010212277A - Film forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To form a semiconductor film excellent in crystallinity. <P>SOLUTION: A film forming apparatus includes a processing chamber 10, and a first electrode 21 and a second electrode 25 which are disposed opposing to each other in the inside of the processing chamber 10. A recess portion 22 having a gas inlet port 23 in the inside is provided on the second electrode 25 side of the first electrode 21. The recess portion 22 has a hollow discharging portion 22h configured to improve the electron density in a plasma state of a material gas introduced from the gas inlet port 23, and a buffer portion 22b for promoting a reaction of the material gas dissociated in the hollow discharging portion 22h and supplying the material gas to the inside of the processing chamber 10. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a film forming apparatus.

  The plasma CVD (Chemical Vapor Deposition) method is known as a method for forming a semiconductor film or the like using plasma, and is used for manufacturing integrated circuits, liquid crystal display panels, organic electroluminescence elements, solar cells, and the like. Yes.

  A plasma CVD apparatus for forming a film by using this plasma CVD method includes a cathode electrode and an anode electrode arranged so as to face each other inside a processing chamber. For example, the anode electrode is provided in a substrate holder disposed on the upper wall portion of the processing chamber, and a substrate to be processed such as a glass substrate is mounted on the surface on the cathode electrode side by the substrate holder. In the cathode electrode, a plurality of gas inlets for introducing a source gas for film formation into the processing chamber are formed on the anode electrode side.

  In this plasma CVD apparatus, a substrate to be processed is mounted on an anode electrode, and the inside of the processing chamber is decompressed with a vacuum pump or the like, and a source gas is introduced into the processing chamber from each gas inlet, and a cathode electrode and an anode electrode By applying a voltage between the two, a plasma state of the source gas is generated as a glow discharge phenomenon by dielectric breakdown of the generated electric field. Thus, dissociation of the source gas (gas molecules) is promoted and radicals are generated in the cathode sheath portion where the relatively strong electric field is formed in the vicinity of the cathode electrode and in the vicinity thereof. The radicals generated in this way diffuse to the substrate to be processed and deposit on the surface of the substrate, thereby forming a thin film.

  As this plasma CVD apparatus, for example, in Patent Document 1, a plurality of gas blowing holes larger in diameter than the respective gas inlets are provided on the upper side of the cathode electrode so as to communicate with the respective gas inlets. An apparatus is disclosed in which the diameter is set to an appropriate size in relation to the distance of the plasma sheath formed near the inner surface of each hole. According to this, it is described that a more stable plasma can be generated and a thin film having a uniform film thickness and film quality can be formed at a high speed.

JP 2001-155997 A

  By the way, as a means for improving the performance of a thin film transistor formed using a plasma CVD apparatus, a microcrystalline silicon film having a higher carrier mobility than an amorphous silicon film (a state in which a crystalline component and an amorphous component are mixed) For example, the semiconductor layer may be formed of a crystalline silicon film such as a silicon film.

  However, in the above-described plasma CVD apparatus, since radicals generated by dissociation of the source gas are likely to diffuse into the processing chamber, the reaction between radicals is difficult to promote so that crystal components are generated, and the crystal CVD has sufficient crystallinity. It is difficult to form a silicon film.

  The present invention has been made in view of such various points, and an object thereof is to form a semiconductor film having good crystallinity.

  In order to achieve the above object, according to the present invention, a hollow discharge portion in which the concave portion provided in the first electrode is configured to increase the electron density in the plasma state of the raw material gas introduced from the gas introduction port; And a buffer section for promoting the reaction of the source gas dissociated in the hollow discharge section and supplying it to the inside of the processing chamber.

  Specifically, a film forming apparatus according to the present invention includes a processing chamber, and a first electrode and a second electrode disposed so as to face each other inside the processing chamber, and the second electrode of the first electrode. A gas inlet for introducing a raw material gas into the inside of the processing chamber is provided on the electrode side, and the raw material gas is brought into a plasma state by applying a voltage between the first electrode and the second electrode, A film forming apparatus for forming a semiconductor film on a substrate to be processed by exposing the substrate to be processed to the plasma source gas, wherein the first electrode is provided with a recess having the gas introduction port therein. And the concave portion promotes a reaction between the hollow discharge portion configured to increase the electron density in the plasma state of the source gas introduced from the gas inlet and the source gas dissociated in the hollow discharge portion. Let the inside of the processing chamber Characterized in that it has a buffer for supplying.

  According to the above configuration, the first electrode is provided with a recess having a gas inlet therein, and the recess is configured to increase the electron density in the plasma state of the source gas introduced from the gas inlet. And a buffer part for promoting the reaction of the source gas dissociated in the hollow discharge part and supplying it to the inside of the processing chamber. As a result, when a source gas is introduced from the gas inlet and a voltage is applied between the first electrode and the second electrode, a hollow discharge occurs in the hollow discharge portion, and in the hollow discharge portion and in the vicinity of the opening. Since the electron density in the plasma source gas is increased, dissociation of the source gas (gas molecules) is promoted to generate high-density radicals. In the buffer portion, the dispersion of the raw material gas is suppressed, whereby the reaction frequency between radicals in the raw material gas generated in the hollow discharge portion is increased, and the generation of the crystal component is promoted. Therefore, a semiconductor film with favorable crystallinity is formed on the substrate to be processed.

  In this specification, the hollow discharge is generated in a hollow portion such as a recess or a through hole provided in the electrode, and the electron density (plasma density) in the plasma state of the source gas is increased in the vicinity of the hollow portion and the opening. It is a discharge phenomenon.

  The gas inlet is formed at the bottom of the recess, the hollow discharge portion is formed in a cylindrical shape with a relatively small inner diameter on the bottom side of the recess, and the buffer portion communicates with the hollow discharge portion. Thus, it is preferable that it is formed in a cylindrical shape with a relatively large inner diameter on the opening side of the recess.

  According to this configuration, since the hollow discharge part is formed in a cylindrical shape, the electron density in the source gas is increased by the hollow discharge in the hollow discharge part compared to the case where the hollow discharge part is formed in a groove shape or the like. The dissociation rate of the raw material gas is further increased. Since the buffer portion is formed in a cylindrical shape, the dispersion of the raw material gas in the buffer portion is further suppressed as compared with the case where the buffer portion is formed in a groove shape or the like. The frequency of reaction between radicals further increases, and the generation of crystal components is favorably promoted.

  Further, the product value of the pressure of the source gas and the inner diameter of the hollow discharge portion is in a range of 0.2 Pa · m to 1.0 Pa · m, and the depth of the hollow discharge portion is It is preferably in the range of 2 to 3 times the inner diameter of the discharge part.

  If the product of the pressure of the raw material gas and the inner diameter of the hollow discharge part is less than 0.2 Pa · m or larger than 1.0 Pa · m, the hollow discharge part is unlikely to generate a hollow discharge, and the raw material gas It is difficult to increase the electron density in the plasma state. Also, if the depth of the hollow discharge part is less than twice the inner diameter of the hollow discharge part, the internal area of the hollow discharge part is relatively small, so the dissociation rate of the source gas in this hollow discharge part Is relatively low. On the other hand, when the depth of the hollow discharge part is larger than three times the inner diameter of the hollow discharge part, the depth of the hollow discharge part is less than three times the inner diameter of the hollow discharge part. It is difficult to increase the gas dissociation rate.

  On the other hand, as in the above configuration, the product of the pressure of the source gas and the inner diameter of the hollow discharge portion is in the range of 0.2 Pa · m to 1.0 Pa · m, and the depth of the hollow discharge portion is Is in the range of not less than 2 times and not more than 3 times the inner diameter of the hollow discharge part, hollow discharge is reliably generated in the hollow discharge part, and the electron density in the plasma state of the source gas is favorably increased, The dissociation rate of the source gas is sufficiently increased.

  The depth of the buffer portion is preferably in the range of 2 to 3 times the inner diameter of the buffer portion.

  If the depth of the buffer portion is less than twice the inner diameter of the buffer portion, the distance (depth) at which the diffusion of the source gas is suppressed relative to the region (inner diameter) where the source gas spreads in the buffer portion. Is relatively short, it is difficult to sufficiently promote the reaction of the raw material gas. On the other hand, when the depth of the buffer portion is larger than three times the inner diameter of the buffer portion, the reaction of the raw material gas is smaller than when the depth of the buffer portion is not more than three times the inner diameter of the buffer portion. Hard to be promoted.

  In contrast, as described above, when the depth of the buffer portion is in the range of 2 to 3 times the inner diameter of the buffer portion, the reaction of the source gas is sufficiently promoted in the buffer portion. The

  The first electrode may be a cathode electrode, and the second electrode may be an anode electrode.

  Even in this configuration, the hollow cathode discharge, which is a hollow discharge at the cathode electrode, is generated in the hollow discharge portion, so that the electron density in the raw material gas in the plasma state is increased in the hollow discharge portion and in the vicinity of the opening thereof, and thus in the raw material gas. In the buffer portion, the frequency of reaction between radicals in the raw material gas is increased and the generation of crystal components is promoted, so that the effects of the present invention are specifically demonstrated.

  You may have a board | substrate holding means which hold | maintains the said to-be-processed substrate in the state contacted with the said 2nd board | substrate between the said 1st electrode and the said 2nd electrode.

  According to this configuration, it is possible to form a semiconductor film with good crystallinity on the substrate to be processed due to the effects of the present invention.

  Further, the substrate holding means for holding the substrate to be processed is provided so as to face the first electrode through the second electrode, and the substrate to be processed held by the substrate holding means is provided on the second electrode. A through hole for flowing the source gas may be formed on the side.

  Also with this configuration, it is possible to form a semiconductor film with favorable crystallinity on the substrate to be processed due to the effects of the present invention. When a semiconductor film is formed on the substrate to be processed while the substrate to be processed is held on the second substrate between the first electrode and the second electrode, ions in the source gas in the plasma state are not covered. The film is accelerated by the sheath portion of the second electrode formed on the surface of the processing substrate, and the film formation surface of the processing substrate is damaged by ion bombardment. Therefore, ion bombardment on the film formation surface of the substrate to be processed is suppressed, and a high-quality semiconductor film can be formed.

  The through-hole preferably has a hollow discharge portion configured to increase the electron density in the plasma state of the source gas.

  According to this configuration, when a voltage is applied between the first electrode and the second electrode, a hollow discharge is generated in the hollow discharge portion of the through hole, so that in the hollow discharge portion of the through hole and in the vicinity of the opening thereof, Since the electron density in the plasma state of the source gas is increased and the dissociation of the unreacted source gas (gas molecules) is promoted to further generate radicals, the deposition rate on the substrate to be processed is increased.

  The hollow discharge portion of the through hole is formed in a cylindrical shape, and the product value of the pressure of the source gas and the inner diameter of the hollow discharge portion of the through hole is in a range of 0.2 Pa · m to 1.0 Pa · m. The length of the hollow discharge portion of the through hole is preferably in the range of 2 to 3 times the inner diameter of the hollow discharge portion.

  If the value of the product of the pressure of the source gas and the inner diameter of the hollow discharge portion of the through hole is less than 0.2 Pa · m or greater than 1.0 Pa · m, then hollow discharge occurs in the hollow discharge portion of the through hole. It is difficult to generate and the electron density in the plasma state of the source gas is difficult to increase. In addition, if the length of the hollow discharge portion of the through hole is less than twice the inner diameter of the hollow discharge portion, the dissociation rate of the source gas is relatively low. On the other hand, when the length of the hollow discharge portion of the through hole is larger than three times the inner diameter of the hollow discharge portion, the depth of the hollow discharge portion of the through hole is not more than three times the inner diameter of the hollow discharge portion. Compared to the case, it is difficult to increase the dissociation rate of the source gas.

  On the other hand, as in the above configuration, the product of the pressure of the source gas and the inner diameter of the hollow discharge portion of the through hole is in the range of 0.2 Pa · m to 1.0 Pa · m, and the through hole When the length of the hollow discharge part is in the range of 2 to 3 times the inner diameter of the hollow discharge part, the hollow discharge is reliably generated in the hollow discharge part of the through hole, and the plasma state of the source gas The electron density in is improved satisfactorily, and the dissociation rate of the source gas is sufficiently increased.

  Further, the through hole has a buffer part for promoting the reaction of the source gas on at least one of the first electrode side and the opposite side of the first electrode in the hollow discharge part of the through hole. It is preferable.

  According to this configuration, when the through hole has a buffer part on the first electrode side of the hollow discharge part, the reaction frequency of radicals generated in the vicinity of the opening on the first electrode side of the hollow discharge part in the buffer part. And the generation of crystal components is further promoted. In addition, when the through hole has a buffer part on the opposite side of the first electrode of the hollow discharge part, the dispersion of the source gas is suppressed in the buffer part, and the radicals generated via the hollow discharge part The frequency of reaction increases and the production of crystal components is further promoted. Therefore, the crystallinity of the semiconductor film to be formed is further improved.

  And it is preferable that the said through-hole has the said buffer part in the said 1st electrode side in the hollow discharge part of this through-hole, and the opposite side to this 1st electrode.

  According to this configuration, since the buffer part is provided on both the first electrode side and the opposite side of the first electrode in the hollow discharge part, the radicals generated by dissociation of the source gas (gas molecule) Since the reaction frequency increases as much as possible, the crystallinity of the deposited semiconductor film is further improved.

  According to the present invention, the concave portion provided in the first electrode is dissociated between the hollow discharge portion configured to increase the electron density in the plasma state of the raw material gas introduced from the gas introduction port, and the hollow discharge portion. In addition, since it has a buffer portion for promoting the reaction of the source gas and supplying it to the inside of the processing chamber, a semiconductor film with good crystallinity can be formed.

It is sectional drawing which shows the plasma CVD apparatus of Embodiment 1 roughly. FIG. 3 is a perspective view schematically showing a plasma discharge generating part of the first embodiment. 3 is a plan view schematically showing a part of the cathode electrode of Embodiment 1. FIG. 2 is a cross-sectional view schematically showing a part of the cathode electrode of Embodiment 1. FIG. 6 is a plan view schematically showing a part of a cathode electrode of Comparative Example 1. FIG. 4 is a cross-sectional view schematically showing a part of a cathode electrode of Comparative Example 1. FIG. 6 is a plan view schematically showing a part of a cathode electrode of Comparative Example 2. FIG. 6 is a cross-sectional view schematically showing a part of a cathode electrode of Comparative Example 2. FIG. It is a graph which shows the component ratio of each silicon film formed into a film by the plasma CVD apparatus of an Example. 6 is a graph showing the component ratio of each silicon film formed by the plasma CVD apparatus of Comparative Example 1. FIG. 6 is a graph showing the component ratio of each silicon film formed by the plasma CVD apparatus of Comparative Example 2. FIG. It is a graph which shows the ratio of the Si-H coupling | bonding with respect to the Si-H2 coupling | bonding of each silicon film formed with the plasma CVD apparatus of the Example and the comparative examples 1 and _2. FIG. It is a graph which shows the volume resistivity of each silicon film formed into a film by the plasma CVD apparatus of an Example and Comparative Examples 1 and 2. FIG. It is sectional drawing which shows the plasma CVD apparatus of Embodiment 2 roughly. It is a perspective view which shows the plasma discharge generation | occurrence | production part of Embodiment 2 roughly. 6 is a cross-sectional view schematically showing a part of an anode electrode according to Embodiment 2. FIG. It is sectional drawing which shows roughly a part of anode electrode of the plasma CVD apparatus of Embodiment 3. It is sectional drawing which shows schematically a part of anode electrode of the plasma CVD apparatus of other embodiment. It is sectional drawing which shows schematically a part of anode electrode of the plasma CVD apparatus of other embodiment.

  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 embodiments.

Embodiment 1 of the Invention
1 to 4 show Embodiment 1 of a film forming apparatus according to the present invention. FIG. 1 is a cross-sectional view schematically showing a plasma CVD apparatus 1 of the present embodiment. FIG. 2 is a perspective view schematically showing the plasma discharge generator 20 of the plasma CVD apparatus 1. FIG. 3 is a plan view schematically showing a part of the cathode electrode 21 of the plasma discharge generator 20. FIG. 4 is a cross-sectional view schematically showing a part of the cathode electrode 21.

  As shown in FIG. 1, a plasma CVD (Chemical Vapor Deposition) apparatus 1 that is a film forming apparatus of the present embodiment includes a processing chamber 10 in which a processing target substrate 5 such as a glass substrate is disposed, and a processing chamber 10. A plasma discharge generator 20 provided inside is provided, and a thin film is formed by performing plasma processing on the substrate 5 to be processed.

  As shown in FIGS. 1 and 2, the plasma discharge generation unit 20 includes a cathode electrode 21 that is a first electrode and an anode electrode 25 that is a second electrode that are disposed in the processing chamber 10 so as to face each other in the vertical direction. And a pair of plate-like electrodes. The plasma discharge generation unit 20 is applied with a voltage between the cathode electrode 21 and the anode electrode 25, so that a source gas for film formation (hereinafter simply referred to as a gas) as a glow discharge phenomenon due to dielectric breakdown of the generated electric field. ) To generate a plasma state.

  As shown in FIG. 1, the anode electrode 25 is provided in a substrate holder 11 that is a substrate holding means fixed to the upper wall portion in the processing chamber 10. The substrate holder 11 is configured to hold the substrate 5 to be processed between the cathode electrode 21 and the anode electrode 25 by holding the substrate 5 to be mounted on the lower surface of the anode electrode 25. Has been. Further, the substrate holder 11 is provided with a heater (not shown) for heating the substrate to be processed 5 on the back side (upper side in the drawing) so that the substrate to be processed 5 is heated when the film forming process is performed. It is configured.

  The cathode electrode 21 is disposed below the anode electrode 25, and is provided on a chamber-like gas retention part 16 provided in the processing chamber 10 via a plate-like dielectric part 17. The dielectric portion 17 is made of aluminum oxide or the like, and is provided to electrically separate the cathode electrode 21 and the gas retention portion 16.

  As shown in FIGS. 2 and 3, the cathode electrode 21 is provided with a plurality of recesses 22 arranged in a staggered pattern on the anode electrode 25 side. As shown in FIG. 3, each of these recesses 22 is formed in a circular shape in plan view, and a gas inlet 23 that penetrates the cathode electrode 21 in the thickness direction is formed at the bottom. As shown in FIG. 1, each of these gas inlets 23 is formed so as to penetrate the dielectric portion 17 together with the cathode electrode 21, and to communicate the inside of each recess 22 and the gas retention portion 16.

  Then, as shown in FIG. 4, each recess 22 is dissociated by a hollow discharge part 22h configured to increase the electron density in the plasma state of the gas introduced from the gas inlet 23, and the hollow discharge part 22h. And a buffer portion 22b for promoting the reaction of the gas and supplying the gas into the processing chamber 10.

  Each hollow discharge portion 22 h is formed in a cylindrical shape with a relatively small inner diameter on the bottom side of each recess 22, and has a concave shape that expands from the upper opening portion of the gas inlet 23 toward the opening side of each recess 22. The gas inlet 23 communicates with the bottom 22t. Each of these hollow discharge portions 22h is configured to generate a hollow cathode discharge, which is a hollow discharge at the cathode electrode 21, when a voltage is applied between the cathode electrode 21 and the anode electrode 25. The electron density in the plasma state of the gas is increased in the hollow discharge portion 22h and in the vicinity of the openings. The inner diameter a1 and the depth b1 of each hollow discharge portion 22h are defined by the pressure of the gas introduced into the processing chamber 10.

  If the value of the product of the pressure of the introduced gas and the inner diameter a1 of each hollow discharge portion 22h is less than 0.2 Pa · m or greater than 1.0 Pa · m, each hollow discharge portion 22h has a hollow cathode. It is difficult for discharge to occur, and the electron density in the plasma state of the gas is difficult to increase. Further, if the depth b1 of each hollow discharge portion 22h is less than twice the inner diameter a1 of each hollow discharge portion 22h, the internal area of each hollow discharge portion 22h is relatively small, so that the gas dissociation The rate is relatively low. On the other hand, when the depth b1 of each hollow discharge part 22h is larger than three times the inner diameter a1 of each hollow discharge part 22h, the depth b1 of each hollow discharge part 22h is the inner diameter a1 of each hollow discharge part 22h. The gas dissociation rate is unlikely to increase as compared to the case of 3 times or less.

  Therefore, each hollow discharge portion 22h has a product value of the pressure of the introduced gas and its inner diameter a1 in the range of 0.2 Pa · m to 1.0 Pa · m, and the depth b1 thereof is It is formed so as to be in the range of 2 to 3 times the inner diameter a1.

  Each buffer part 22b is formed in a cylindrical shape with a relatively large inner diameter relative to the hollow discharge part 22h on the opening side of each concave part 22 so as to communicate with the hollow discharge part 22h, and an upper opening part of each hollow discharge part 22h. Are formed so as to extend with the same diameter after being expanded toward the opening side of each recess 22. The depth b2 of each buffer portion 22b is defined by the size of the inner diameter a2 of the same diameter portion of each buffer portion 22b.

  If the depth b2 of each buffer portion 22b is less than twice the inner diameter a2 of each buffer portion 22b, gas diffusion to the region (inner diameter a2) where the gas spreads in each buffer portion 22b. Since the distance (depth b2) in which the gas is suppressed is relatively short, the gas reaction is hardly promoted sufficiently. On the other hand, when the depth b2 of each buffer portion 22b is larger than three times the inner diameter a2 of each buffer portion 22b, the depth b2 of each buffer portion 22b is not more than three times the inner diameter a2 of each buffer portion 22b. Compared with the case where it is, it is hard to promote reaction of gas.

  From this, each buffer part 22b is formed so that the depth b2 is in the range of not less than twice and not more than three times the inner diameter a2.

  Further, as shown in FIG. 1, a high-frequency power source 12 that supplies power to the plasma discharge generation unit 20, a gas supply unit 13 that supplies gas into the processing chamber 10, and the processing chamber 10 are provided outside the processing chamber 10. A gas discharge part 14 for discharging the gas inside is provided.

  The high frequency power supply 12 is configured to generate a high frequency voltage having a frequency of 13.56 MHz or the like, and is connected to the cathode electrode 21. On the other hand, the anode electrode 25 is grounded. The high frequency power supply 12 may be configured to generate a high frequency voltage of 40 MHz, 100 MHz or higher, for example.

  The gas supply unit 13 includes a gas cylinder or the like, and is connected to the gas retention unit 16 through a gas supply pipe 18. As the gas discharge part 14, a mechanical booster pump, a rotary pump, etc. are used, for example. The plasma CVD apparatus 1 is configured to be able to introduce a gas into the processing chamber 10 so as to have a pressure of, for example, about 10 to 3000 Pa. After supplying the gas from the gas supply unit 13 to the gas retention unit 16 once, The gas is supplied to the space between the cathode electrode 21 and the anode electrode 25 via each gas inlet 23 and the recess 22.

-Film formation method-
Next, a method for forming a film on the substrate 5 to be processed using the plasma CVD apparatus 1 will be described. In this embodiment, a case where a microcrystalline silicon film is formed will be described as an example.

First, the substrate 5 to be processed is carried into the processing chamber 10 using a transfer robot or the like, held on the substrate holder 11 and mounted on the surface of the anode electrode 25. Next, the inside of the processing chamber 10 is decompressed by driving the gas discharge unit 14. Thereafter, the gas is introduced into the processing chamber 10 by driving the gas supply unit 13 while the gas discharge unit 14 is driven. As the gas, for example, monosilane gas (SiH ₄ ) and hydrogen gas (H ₂ ) are used. As indicated by an arrow 6 in FIG. 1, the gas is once supplied from the gas supply unit 13 to the gas retention unit 16 and then introduced into the processing chamber 10 from each gas introduction port 23 through each recess 22. The When the high-frequency power source 12 is driven together with the introduction of the gas and a high-frequency voltage is applied between the cathode electrode 21 and the anode electrode 25, the plasma state 7 of the gas is generated as a glow discharge phenomenon due to dielectric breakdown of the generated electric field. Let

  At this time, in the cathode electrode 21, hollow cathode discharge is generated in the hollow discharge portion 22h of each concave portion 22, and the electron density in the gas 7 in the plasma state is increased in each hollow discharge portion 22h and in the vicinity of the openings. As a result, dissociation of the gas (gas molecules) 7 is promoted, and high-density radicals are generated. And in each buffer part 22b, the dispersion | distribution of the gas 7 containing the high density radical produced | generated in each hollow discharge part 22h is suppressed, the reaction frequency of the radicals in the gas 7 increases, and a crystal | crystallization component Generation is promoted. Here, the arrow 8 in FIG. 1 shows the flow of the gas 7 containing a crystal component. When the gas 7 containing radicals and crystal components generated in this way flows to the substrate 5 to be processed and the substrate 5 is exposed to the gas 7, unreacted radicals and crystal components are deposited on the surface of the substrate. Thus, a microcrystalline silicon film is formed.

  After the film formation on the substrate 5 to be processed is finished, the driving of the high-frequency power source 12 and the gas supply unit 13 is stopped, and the gas in the processing chamber 10 is discharged by continuing to drive the gas discharge unit 14. Then, using the transfer robot or the like, the substrate 5 to be processed is removed from the substrate holder 11 and carried out of the processing chamber 10. Thus, the film forming process on the substrate to be processed 5 is completed.

-Example-
Next, an example in which a film forming process of a microcrystalline silicon film is actually performed using the plasma CVD apparatus 1 of the present embodiment will be described.

  In the plasma CVD apparatus 1 of the present embodiment, the cathode electrode 21 has a thickness of 15.0 mm. The recesses 22 are provided adjacent to each other at a pitch of 2.9 mm. In each of these recesses 22, the hollow discharge portion 22h has an inner diameter a1 of 1.2 mm and a depth b1 of 2.5 mm, and the buffer portion 22b has an inner diameter a2 of 2.2 mm and a depth b2 of 6.0 mm. ing. Each gas inlet 23 has an inner diameter of 0.5 mm and a length of 6.5 mm. Further, as the high-frequency power source 12, a power source having a frequency of 40 MHz was used, and a pulse discharge was generated in the plasma discharge generator 20 to perform the film forming process. A glass substrate was applied to the substrate 5 to be processed.

  In the film forming process of the present embodiment, monosilane gas and hydrogen gas are introduced into the processing chamber 10 so as to have a pressure of 740 Pa while maintaining the temperature in the processing chamber 10 at 250 ° C. A film was formed. In this example, the ratio of the monosilane gas flow rate to the hydrogen gas flow rate was changed, and the silicon film was formed with each gas having a different ratio between the monosilane gas and the hydrogen gas. Specifically, by changing the flow rate of monosilane gas while keeping the flow rate of hydrogen gas constant at 300 sccm (standard cubic centimeter per mitute), the ratio of these gases is expressed as “R = flow rate of hydrogen gas / flow rate of monosilane gas”. The guided R was changed to take values of 250, 227, 208, 192, 178, 156, and 147. Here, “sccm” is a flow rate in cubic centimeters flowing every minute at 0 ° C.

  Moreover, as a comparative example, the plasma CVD apparatus of comparative example 1 that does not have a buffer portion in each recess 101 of the cathode electrode 100 and the plasma CVD apparatus of comparative example 2 that does not have each recess in the cathode electrode 200, respectively. In the same manner as in the example, a silicon film was formed on the glass substrate 5. The plasma CVD apparatuses of Comparative Examples 1 and 2 are the same as the plasma CVD apparatus 1 of the embodiment except for the cathode electrode. Cathode electrodes 100 and 200 in the plasma CVD apparatus of Comparative Examples 1 and 2 are shown in FIGS.

  In the plasma CVD apparatus of Comparative Example 1, the cathode electrode 100 has a thickness of 9.5 mm. As shown in FIGS. 5 and 6, the cathode electrode 100 is provided with a plurality of recesses 101 arranged in a staggered pattern on the anode electrode side of the cathode electrode 100, and the cathode electrode 100 penetrates the bottom of each recess 101. A gas inlet 102 is formed. Each recess 101 is provided adjacent to each other at a pitch of 1.9 mm, and is composed of a bottom portion 101t and a hollow discharge portion 101h. The bottom portion 101t and the hollow discharge portion 101h are formed in the same manner as the bottom portion 22t and the hollow discharge portion 22h of the cathode electrode 21 of the embodiment, and the hollow discharge portion 101h communicates with the gas inlet 102 via the bottom portion 101t. Each hollow discharge portion 101h has an inner diameter x of 1.2 mm and a length y of 2.5 mm. Each gas inlet 102 has an inner diameter of 0.5 mm and a length of 6.5 mm. In the plasma CVD apparatus of Comparative Example 1, the ratio of monosilane gas to hydrogen gas was changed so that the above R values were 250, 208, 178, and 156, and silicon films were formed with the respective ratio gases.

  In the plasma CVD apparatus of Comparative Example 2, the cathode electrode 200 has a thickness of 9.5 mm. As shown in FIGS. 7 and 8, the cathode electrode 200 is provided with a plurality of gas introduction ports 201 penetrating the cathode electrode 200 in a staggered manner. Each gas inlet 201 is provided adjacent to each other at a pitch of 1.9 mm, and has an inner diameter of 0.5 mm. In the plasma CVD apparatus of Comparative Example 2, the ratio of monosilane gas to hydrogen gas was changed so that the R had the values of 250, 208, and 178, and silicon films were formed with the respective ratio gases.

  And about each silicon film formed into a film using the plasma CVD apparatus of these Examples and comparative examples 1 and 2, component analysis, analysis of the formation state of a silicon network, and measurement of volume resistivity were performed, and these The crystallinity of each silicon film was evaluated.

<Component analysis>
Spectral waveforms obtained by measurement by Raman spectroscopy were peak-separated, and the ratio of the amorphous component, nanocluster component, nanocrystal component, and microcrystal component in each silicon film was determined from the waveform area ratio of these components.

  The component ratio of each silicon film is shown in FIGS. 9 to 11 show the component ratio of each silicon film on the vertical axis and the ratio (R) of monosilane gas to hydrogen gas on the horizontal axis. FIG. 9 is a graph showing the component ratio of a silicon film formed using the plasma CVD apparatus 1 of the example. FIG. 10 is a graph showing the component ratio of a silicon film formed using the plasma CVD apparatus of Comparative Example 1. FIG. 11 is a graph showing the component ratio of a silicon film formed using the plasma CVD apparatus of Comparative Example 2.

  For each silicon film formed by the plasma CVD apparatus of Comparative Example 1, as shown in FIG. 10, the microcrystal components are all below 35%. As for the silicon film formed by the plasma CVD apparatus of Comparative Example 2, as shown in FIG. 11, although the R value of the silicon film having a value of 250 exceeds 40%, the other R Is less than 40% of the microcrystal component of each silicon film having values of 208 and 178.

  On the other hand, in the silicon film formed by the plasma CVD apparatus 1 of the example, as shown in FIG. 9, the R value of 178, 156, 147 is 40% of the microcrystal component of each silicon film. However, the R value of 250, 227, 208, and 192 in each silicon film exceeds 40%. Therefore, according to the plasma CVD apparatus 1 of the example, compared with the case where the silicon film is formed using the plasma CVD apparatus of Comparative Examples 1 and 2, the ratio (R) of monosilane gas to hydrogen gas is wider. It was found that a microcrystalline silicon film having a large amount of microcrystal components can be formed over a long period of time.

<Analysis of silicon network formation>
Spectral waveforms obtained by measurement by Raman spectroscopy were peak-separated, and the ratio of Si—H bonds to Si—H ₂ bonds in each silicon film was determined from the waveform area ratio. For calculating the waveform area ratio, the waveform area of the Si-H bond has a Raman shift peak in the vicinity of 2000 cm ⁻¹ , and the Si—H ₂ bond has a waveform of the Raman shift peak in the vicinity of 2100 cm ^−1. Each area was used.

  The analysis of the silicon network formation state was performed on each silicon film having the above R values of 156, 178, 208, and 250 for the silicon film formed by the plasma CVD apparatus 1 of the example. In addition, for silicon films formed by the plasma CVD apparatus of Comparative Example 1, each of the above R films has a value of 178, 208, 250, and for all silicon films formed by the plasma CVD apparatus of Comparative Example 2, Each analysis was performed on the silicon film.

FIG. 12 shows the ratio of Si—H bonds to Si—H ₂ bonds in each silicon film. 12, the ratio of Si-H bonds and _{Si-H 2} bonds shown on the vertical axis as "Si-H bond / _{Si-H 2} bonds", in the plasma CVD apparatus of the embodiment and Comparative Examples 1 and 2 is a graph illustrating, as arranged in this order in the horizontal direction the ratio of Si-H bonds and Si-H ₂ bonds for the formed silicon film.

As shown in FIG. 12, the silicon film formed by the plasma CVD apparatus 1 of the example is more Si-Si than the silicon film formed by the plasma CVD apparatus of Comparative Example 2 with respect to the silicon film in which R has a value of 178. Although the ratio of Si—H bonds to —H ₂ bonds is slightly lower, the other silicon films having the above R values of 208 and 250 are formed by the plasma CVD apparatus of Comparative Examples 1 and 2. The ratio of Si—H bonds to Si—H ₂ bonds is higher than that of the silicon film, that is, the ratio in which three of the four bonds of silicon are bonded to other silicon is high. Therefore, according to the plasma CVD apparatus 1 of the example, compared with the case where the silicon film is formed using the plasma CVD apparatus of Comparative Examples 1 and 2, the ratio (R) of monosilane gas to hydrogen gas is wider. It was found that a microcrystalline silicon film having many silicon bonds can be formed.

<Measurement of volume resistivity>
The volume resistivity of each silicon film was measured with a high resistivity meter. The volume resistivity was measured for each silicon film having the above R values of 147, 156, 178, 192, 208, 250 for the silicon film formed by the plasma CVD apparatus 1 of the example. In addition, for silicon films formed by the plasma CVD apparatus of Comparative Example 1, each of the above R films has a value of 178, 208, 250, and for all silicon films formed by the plasma CVD apparatus of Comparative Example 2, Each measurement was performed on the silicon film.

  The volume resistivity of each silicon film is shown in FIG. FIG. 13 shows the volume resistivity of each silicon film on the vertical axis, and the volume resistivity of the silicon films formed by the plasma CVD apparatuses of the example and comparative examples 1 and 2 are arranged in order in the horizontal axis direction. FIG.

As shown in FIG. 13, each silicon film formed by the plasma CVD apparatus of Comparative Example 1 has a volume resistivity higher than 1.0 × 10 ⁶ Ω · cm, and the plasma of Comparative Example 2 Each silicon film formed by the CVD apparatus has a volume resistivity higher than 1.0 × 10 ⁷ Ω · cm. On the other hand, in the silicon film formed by the plasma CVD apparatus 1 of the example, the volume resistivity of each silicon film in which R takes values of 178, 192, 208, 250 is 1.0 × 10 ⁶ Ω · The volume resistivity is lower than that of each of the silicon films of Comparative Examples 1 and 2 that have the same R value, and is particularly smaller than that of the silicon film formed by the plasma CVD apparatus of Comparative Example 2. The volume resistivity is extremely low. From this, according to the plasma CVD apparatus 1 of the example, it is possible to form a microcrystalline silicon film having a lower volume resistivity than when a silicon film is formed using the plasma CVD apparatuses of comparative examples 1 and 2. I understood.

  As described above, according to the plasma CVD apparatus 1 of the embodiment, a crystal containing a large amount of microcrystal components over a wide range of the ratio (R) of monosilane gas and hydrogen gas, and having a large volume of silicon-to-silicon bonds and a low volume resistivity. It has been found that there is an advantageous effect that a microcrystalline silicon film having good properties can be formed.

-Effect of Embodiment 1-
Therefore, according to the first embodiment, the cathode electrode 21 is provided with the plurality of recesses 22 having the gas introduction ports 23 therein, and each of these recesses 22 has an electron density in the plasma state of the gas introduced from the gas introduction ports 23. A hollow discharge portion 22h configured to increase the pressure and a buffer portion 22b for promoting the reaction of the gas dissociated by the hollow discharge portion 22h and supplying the gas into the processing chamber 10 When a voltage is applied between the cathode electrode 21 and the anode electrode 25, a hollow cathode discharge is generated in the hollow discharge portion 22h of each recess 22, and a plasma state is generated in each hollow discharge portion 22h and in the vicinity of the openings. Since the electron density in the gas is increased, the dissociation of the gas (gas molecules) is promoted and high-density radicals are generated. And in each buffer part 22b, dispersion | distribution of gas is suppressed, the reaction frequency of the radicals in the gas produced | generated by the hollow discharge part 22h increases, and the production | generation of a crystal component can be accelerated | stimulated. Therefore, a semiconductor film with favorable crystallinity can be formed over the substrate to be processed.

  Furthermore, since each hollow discharge part 22h is formed in a cylindrical shape, the electron density in the gas is increased by hollow discharge in each hollow discharge part 22h as compared with the case where each hollow discharge part is formed in a groove shape or the like. The gas dissociation rate can be further increased. And since each buffer part 22b is formed in a cylinder shape, compared with the case where each buffer part is formed in a groove shape or the like, it is possible to further suppress gas dispersion in each buffer part 22h. It is possible to further increase the frequency of reaction between the radicals therein, and to favorably promote the generation of crystal components.

  Each hollow discharge portion 22h has a product value of the pressure of the introduced gas and its inner diameter a1 in the range of 0.2 Pa · m to 1.0 Pa · m, and the depth b1 is the inner diameter. Since it is formed so as to be in the range of not less than 2 times and not more than 3 times a1, a hollow cathode discharge is surely generated in each hollow discharge portion 22h, and the electron density in the plasma state of the gas can be increased satisfactorily. The gas dissociation rate can be sufficiently increased.

  Moreover, since each buffer part 22b has the depth b2 in the range of 2 times or more and 3 times or less of the inner diameter a2, the reaction of gas can be sufficiently promoted in each buffer part 22b.

<< Embodiment 2 of the Invention >>
14 to 16 show Embodiment 2 of the film forming apparatus according to the present invention. In the following embodiments, the same parts as those in FIGS. 1 to 4 are denoted by the same reference numerals, and detailed description thereof is omitted. FIG. 14 is a cross-sectional view schematically showing the plasma CVD apparatus 2 of the present embodiment. FIG. 15 is a perspective view schematically showing the plasma discharge generator 20 of the present embodiment. FIG. 16 is a cross-sectional view schematically showing a part of the anode electrode 25 of the present embodiment.

  In the first embodiment, the plasma CVD apparatus 1 that performs the film forming process with the substrate 5 mounted on the surface of the anode electrode 25 between the cathode electrode 21 and the anode electrode 25 by the substrate holder 11 has been described. The plasma CVD apparatus 2 of the present embodiment is configured to perform a film forming process with the substrate to be processed 5 held in the processing chamber 10 so as to face the cathode electrode 21 with the anode electrode 25 interposed therebetween.

  As shown in FIG. 14, the plasma CVD apparatus 2 of the present embodiment includes a processing chamber 10 and a plasma discharge generation unit 20, and similarly to the first embodiment, a high-frequency power source 12, a gas supply unit 13, a gas discharge unit 14, and A gas retention part 16 is provided.

  A substrate support 30 as a substrate holding means is provided at the bottom of the processing chamber 10 so that the substrate 5 to be processed is placed on the substrate support 30 and held by an electrostatic chuck or the like. It is configured. The substrate support 30 is provided with a heater (not shown) for heating the substrate 5 to be processed on the back side (lower side in the drawing), and heats the substrate 5 during film formation. It is configured as follows.

  As shown in FIGS. 14 and 15, the plasma discharge generator 20 is provided on the upper wall side of the processing chamber 10 so as to face the substrate support 30, and is opposed to each other as in the first embodiment. A plate-like cathode electrode 21 and an anode electrode 25 are provided. The cathode electrode 21 is provided below the gas retention part 16 via the dielectric part 17, and the anode electrode 25 is provided between the cathode electrode 21 and the substrate support 30.

  The cathode electrode 21 is formed in the same manner as in the first embodiment. That is, a plurality of recesses 22 are provided on the anode electrode 25 side of the cathode electrode 21 in a zigzag manner and have gas introduction ports 23 at the bottom, and each of these recesses 22 has a gas introduced from the gas introduction port 23. A hollow discharge part 22h configured to increase the electron density in the plasma state, and a buffer part 22b for promoting the reaction of the gas dissociated by the hollow discharge part 22h and supplying the gas into the processing chamber 10 are provided. ing.

  As shown in FIG. 15, the anode electrode 25 is formed with a plurality of through holes 26 arranged in a staggered pattern for flowing gas toward the substrate support base 30. Each through-hole 26 is formed in a cylindrical shape and extends with the same diameter as shown in FIG. Each through hole 26 is configured to generate a hollow anode discharge that is a hollow discharge at the anode electrode 25 when a voltage is applied between the cathode electrode 21 and the anode electrode 25. The electron density in the plasma state of the gas is increased in each through hole 26 and in the vicinity of the openings. The inner diameter c and the length d of each through hole 26 are defined by the pressure of the gas introduced into the processing chamber 10.

  If the value of the product of the pressure of the introduced gas and the inner diameter c of each through hole 26 is less than 0.2 Pa · m or greater than 1.0 Pa · m, a hollow anode discharge is generated in each through hole 26. It is difficult to generate and the electron density in the plasma state of the gas is difficult to increase. Further, if the length d of each through hole 26 is less than twice the inner diameter c of each through hole 26, the internal area of each through hole 26 is relatively small, so the gas dissociation rates are compared. Low. On the other hand, when the length d of each through hole 26 is larger than three times the inner diameter c of each through hole 26, the length d of each through hole 26 is three times or less the inner diameter c of each through hole 26. Compared to the case, it is difficult to increase the gas dissociation rate.

  From this, each through hole 26 has a product value of the pressure of the introduced gas and its inner diameter c in the range of 0.2 Pa · m to 1.0 Pa · m, and its length d is the inner diameter. It is formed so as to be in the range of 2 to 3 times c.

-Film formation method-
Next, a method for forming a film on the substrate 5 to be processed using the plasma CVD apparatus 2 will be described. Also in this embodiment, the case where a microcrystalline silicon film is formed will be described as an example.

First, using the transfer robot or the like, the substrate 5 to be processed is carried into the processing chamber 10 and placed on the substrate support 30 to be held. Next, as in the first embodiment, after reducing the pressure inside the processing chamber 10, monosilane gas (SiH ₄ ) and hydrogen gas (H ₂ ) are introduced into the processing chamber 10, and the cathode electrode 21 and the anode electrode 25 are connected to each other. A plasma state 7 of gas is generated by applying a high-frequency voltage between them.

  At this time, in the cathode electrode 21, as in the first embodiment, a hollow cathode discharge is generated in the hollow discharge portion 22h of each recess 22, and in the gas 7 in the plasma state in each hollow discharge portion 22h and in the vicinity of the opening. The electron density is increased. As a result, dissociation of the gas 7 is promoted and high-density radicals are generated. And in each buffer part 22b, the dispersion | distribution of the gas 7 containing the high density radical produced | generated in each hollow discharge part 22h is suppressed, the reaction frequency of the radicals in the gas 7 increases, and a crystal | crystallization component Generation is promoted.

  Further, in the anode electrode 25, a hollow anode discharge is generated in each through hole 26, and the electron density in the plasma state gas is increased also in each through hole 26 and in the vicinity of the openings. Thereby, dissociation of the unreacted gas 7 is promoted, and radicals are further generated. When the gas 7 containing radicals and crystal components generated in this way flows to the substrate 1 to be processed and the substrate 1 is exposed to the gas 7, unreacted radicals and crystal components are deposited on the surface of the substrate. Thus, a microcrystalline silicon film is formed.

  After film formation on the substrate 1 to be processed, as in the first embodiment, the driving of the high-frequency power source 12 and the gas supply unit 13 is stopped, the gas in the processing chamber 10 is discharged, and film formation is performed. The processed substrate 5 to be processed is carried out of the processing chamber 10. Thus, the film forming process on the substrate to be processed 5 is completed.

-Effect of Embodiment 2-
Therefore, also in the second embodiment, the cathode electrode 21 is provided with a plurality of recesses 22 having the gas introduction ports 23 therein, and each of the recesses 22 has a hollow discharge portion 22h and a buffer portion 22b. A highly reliable semiconductor film can be formed on the substrate 5 to be processed.

  By the way, when a semiconductor film is formed on the substrate to be processed 5 while the substrate to be processed 5 is held on the anode electrode 25 between the cathode electrode 21 and the anode electrode 25, ions in the source gas in the plasma state Is accelerated by the anode sheath portion formed on the surface of the substrate 5 to be processed, and the film forming surface of the substrate 5 is easily damaged by ion bombardment. On the other hand, in the second embodiment, the substrate to be processed 5 is held by the substrate support 30 provided to face the cathode electrode 21 with the anode electrode 25 interposed therebetween. Part is not formed. Thereby, ion bombardment to the film formation surface of the substrate 5 to be processed can be suppressed, and a high-quality semiconductor film can be formed.

  Further, each through hole 26 formed in the anode electrode 25 is configured to generate a hollow anode discharge, and each through hole 26 has a product value of the pressure of the introduced gas and its inner diameter c. The length d is in the range of not less than 0.2 Pa · m and not more than 1.0 Pa · m, and the length d is in the range of not less than 2 times and not more than 3 times the inner diameter c. As a result, when a voltage is applied between the cathode electrode 21 and the anode electrode 25, a hollow anode discharge is reliably generated in each through hole 26, and gas plasma is generated in each of the through holes 26 and in the vicinity of the openings. The electron density in the state increases, dissociation of unreacted gas (gas molecules) is sufficiently promoted, and radicals are further generated. Thereby, the film-forming speed | rate to the to-be-processed substrate 5 can be raised.

<< Embodiment 3 of the Invention >>
FIG. 17 shows Embodiment 3 of the film forming apparatus according to the present invention. FIG. 17 is a cross-sectional view schematically showing a part of the anode electrode 25 of the present embodiment.

  In the second embodiment, the through holes 26 of the anode electrode 25 are hollow discharge portions extending with the same diameter. However, in this embodiment, each through hole 26 is subjected to a hollow anode discharge as shown in FIG. A hollow discharge portion 26h configured to generate, and a pair of buffer portions 26b provided on the cathode electrode 21 side and the substrate support base 30 side of the hollow discharge portion 26h to promote a gas reaction. Yes.

  In the plasma CVD apparatus according to this embodiment, each through-hole 25 of the anode electrode 25 is formed in a cylindrical shape as in the second embodiment. Each hollow discharge portion 26 h is formed in a cylindrical shape with a relatively small inner diameter in the central portion of each through hole 26. Each hollow discharge portion 26h has an inner diameter c1 and a length d1 defined by the pressure of the gas introduced into the processing chamber 10 as in the case of the through hole 26 of the second embodiment, and the gas pressure and the inner diameter c1 The product value is in the range of 0.2 Pa · m to 1.0 Pa · m, and the length d1 is in the range of 2 to 3 times the inner diameter c1.

  Each buffer portion 26b is formed in a cylindrical shape with a relatively large inner diameter relative to the hollow discharge portion 26h on the cathode electrode 21 side and the substrate support base 30 side of the hollow discharge portion 26h in each through hole 26. Each buffer part 26b is formed in the same shape as the buffer part 22b in each concave part 22 of the cathode electrode 21. And each buffer part 26b is the length d2 prescribed | regulated by the internal diameter c2 of the same diameter part similarly to the buffer part 22b in each recessed part 22 of the cathode electrode 21, and is 2 times or more and 3 times or less of the internal diameter c2. It is formed to be in range.

  The configuration other than the anode electrode 25 in the plasma CVD apparatus of the present embodiment is the same as that of the plasma CVD apparatus 2 of the second embodiment. The film forming method using the plasma CVD apparatus of the present embodiment is the same as that of the plasma CVD apparatus 2 of the second embodiment.

-Effect of Embodiment 3-
Therefore, according to the third embodiment, similarly to the second embodiment, a semiconductor film with good crystallinity can be formed on the substrate 5 to be processed, and the deposition rate on the substrate 5 can be increased.

  In addition, since the through-hole 26 has the buffer portion 26b on both the cathode electrode 21 side and the substrate support base 30 side in the hollow discharge portion 26h, the hollow discharge portion In the buffer part 26b on the cathode electrode 21 side of 26h, the reaction frequency between radicals generated in the vicinity of the opening on the cathode electrode 21 side of the hollow discharge part 26h increases, and the generation of crystal components can be further promoted. And in the buffer part 26b by the side of the substrate support 30 of the hollow discharge part 26h, dispersion | distribution of the gas which flows into the substrate support stand 30 side is suppressed, and the reaction frequency of the radicals produced | generated via the hollow discharge part 26h increases. Further, the generation of crystal components can be further promoted. Thereby, the crystallinity of the semiconductor film formed on the substrate to be processed 5 can be further enhanced.

<< Other Embodiments >>
In the first embodiment, the cathode electrode 21 is disposed below the anode electrode 25 and the substrate 5 is mounted on the surface of the anode electrode 25 between the cathode electrode 21 and the anode electrode 25 by the substrate holder 11. As described above, the present invention is not limited to this, and the anode electrode 25 may be disposed below the cathode electrode 21, and the substrate 5 to be processed may be held on the anode electrode 25. In the case of this configuration, for example, the gas supply unit 13 is connected to the upper side of the processing chamber 10 in FIG. 1, and the gas discharge unit 14 is connected to the lower side of the processing chamber 10 in FIG. In addition, the cathode electrode 21 and the anode electrode 25 may be disposed so as to face each other in the width direction of the processing chamber 10 (left and right direction in FIG. 1).

  In the first embodiment, the hollow discharge portion 22h of each recess 22 has a product value of the gas pressure and the inner diameter a1 in the range of 0.2 Pa · m to 1.0 Pa · m, The depth b1 is formed so as to be in the range of not less than 2 times and not more than 3 times the inner diameter a1, but the present invention is not limited to this, and each hollow discharge portion 22h has a gas pressure and its inner diameter a1. May be formed such that the product value is less than 0.2 Pa · m or greater than 1.0 Pa · m, and the depth b1 is less than twice or more than three times the inner diameter a1. It may be formed as follows.

  In the first embodiment, the buffer portion 22b is formed so that the depth b2 thereof is in the range of not less than 2 times and not more than 3 times the inner diameter a2. However, the present invention is not limited to this, and the buffer portion 22b The portion 22b may be formed such that the depth b2 is less than twice or greater than three times the inner diameter a2.

  In the second embodiment, each through hole 26 of the anode electrode 25 has a product value of the gas pressure and its inner diameter c in the range of 0.2 Pa · m to 1.0 Pa · m, and its length. Although d is formed so as to be in the range of not less than 2 times and not more than 3 times the inner diameter c, the present invention is not limited to this, and each through hole 26 has a product of the gas pressure and its inner diameter c. May be formed to be less than 0.2 Pa · m or greater than 1.0 Pa · m, and the length d may be less than 2 times or greater than 3 times the inner diameter c. May be. Further, each through hole 26 may not be configured to generate a hollow anode discharge.

  In the second embodiment, the plate-like anode electrode 25 is provided with the plurality of through holes 26 for flowing gas toward the substrate support base 30. However, the present invention is not limited to this, and the anode electrode 25 may be formed in a mesh shape so that gas flows from the mesh gap to the substrate support base 30 side.

  In the third embodiment, each through hole 26 of the anode electrode 25 has the buffer portions 26b on both sides of the hollow discharge portion 26h on the cathode electrode 21 and substrate support base 30 side. However, the present invention is not limited to this, As shown in FIG. 18, the through-hole 26 may have a buffer part 26b only on the cathode electrode 21 side of the hollow discharge part 26h. Even in such a configuration, in each buffer portion 26b, the reaction frequency between radicals generated in the vicinity of the opening on the cathode electrode 21 side of each hollow discharge portion 26h increases, and the generation of crystal components can be further promoted. The crystallinity of the deposited semiconductor film can be further increased. Further, as shown in FIG. 19, each through hole 26 may have a buffer part 26b only on the substrate support base 30 side of the hollow discharge part 26h. Even in such a configuration, in each buffer portion 26b, since the dispersion of the gas flowing toward the substrate support base 30 side is suppressed and the generation of crystal components can be further promoted, the crystallinity of the semiconductor film to be formed can be further increased. It becomes possible to increase.

  In each of the above embodiments, the plurality of recesses 22 of the cathode electrode 21 are arranged in a staggered manner and are each formed in a circular shape in plan view, but the present invention is not limited to this, and the plurality of recesses 22 They may be arranged in a matrix, etc., may be formed in other shapes such as an ellipse or a rectangle in plan view, and may be formed to extend in a groove shape. That is, each hollow discharge part 22h and the buffer part 22b may also be formed in other shapes such as a rectangular cylinder.

  In the second and third embodiments, the plurality of through holes 26 of the anode electrode 25 are also arranged in a zigzag shape and formed in a cylindrical shape. However, the present invention is not limited to this, and a plurality of through holes 26 are provided. The through holes 26 may also be arranged in a matrix or the like, may be formed in other shapes such as a rectangular tube shape, or may be formed in a slit shape. In the third embodiment, the hollow discharge portion 26h and the buffer portion 26b of each through hole 25 may be formed in other shapes such as a rectangular cylinder.

  In each of the above embodiments, the plasma CVD apparatuses 1 and 2 have been described by taking the case of forming a microcrystalline silicon film as an example. However, the present invention is not limited to this, and a silicon germanium (SiGe) film or zinc selenide is used. The present invention can also be applied to a film forming apparatus for forming another semiconductor film such as a (ZnSe) film.

  As described above, the present invention is useful for a film forming apparatus, and is particularly suitable for a film forming apparatus in which it is desired to form a semiconductor film with good crystallinity.

1, 2 Plasma CVD equipment (film deposition equipment)
5 Substrate 10 Processing chamber 11 Substrate holder (substrate holding means)
21 Cathode electrode (first electrode)
22 Concave portion 22 h Hollow discharge portion 22 b Buffer portion 23 Gas inlet 25 Anode electrode (second electrode)
26 Through-hole 26h Hollow discharge part 26b Buffer part 30 Board | substrate support stand (board | substrate holding means)

Claims (11)

A processing chamber;
A first electrode and a second electrode disposed to face each other inside the processing chamber;
A gas inlet for introducing a source gas into the processing chamber is provided on the second electrode side of the first electrode,
By applying a voltage between the first electrode and the second electrode, the source gas is brought into a plasma state, and the substrate to be processed is exposed to the source gas in the plasma state to form a semiconductor film on the substrate to be processed. A film forming apparatus for forming a film,
The first electrode is provided with a recess having the gas inlet therein.
The concave portion promotes the reaction between the hollow discharge portion configured to increase the electron density in the plasma state of the source gas introduced from the gas inlet and the source gas dissociated in the hollow discharge portion. And a buffer section for supplying the inside of the processing chamber. The film forming apparatus according to claim 1,
The gas inlet is formed at the bottom of the recess,
The hollow discharge portion is formed in a cylindrical shape with a relatively small inner diameter on the bottom side of the recess,
The film forming apparatus, wherein the buffer section is formed in a cylindrical shape with a relatively large inner diameter on the opening side of the recess so as to communicate with the hollow discharge section. The film forming apparatus according to claim 2,
The value of the product of the pressure of the source gas and the inner diameter of the hollow discharge portion is in the range of 0.2 Pa · m to 1.0 Pa · m,
The depth of the hollow discharge part is in the range of 2 to 3 times the inner diameter of the hollow discharge part. In the film-forming apparatus of Claim 2 or 3,
The depth of the buffer section is in the range of 2 to 3 times the inner diameter of the buffer section. In the film-forming apparatus as described in any one of Claims 1-4,
The first electrode is a cathode electrode;
The film forming apparatus, wherein the second electrode is an anode electrode. In the film-forming apparatus of Claim 5,
A film forming apparatus comprising substrate holding means for holding the substrate to be processed in a state of being in contact with the second electrode between the first electrode and the second electrode. In the film-forming apparatus as described in any one of Claims 1-5,
Substrate holding means for holding the substrate to be processed so as to face the first electrode through the second electrode;
The film forming apparatus, wherein the second electrode is formed with a through-hole for flowing the source gas on the substrate to be processed held by the substrate holding means. In the film-forming apparatus of Claim 7,
The film forming apparatus, wherein the through-hole has a hollow discharge portion configured to increase an electron density in a plasma state of the source gas. The film forming apparatus according to claim 8.
The hollow discharge portion of the through hole is formed in a cylindrical shape,
The value of the product of the pressure of the source gas and the inner diameter of the hollow discharge portion of the through hole is in the range of 0.2 Pa · m to 1.0 Pa · m,
The length of the hollow discharge part of the said through-hole exists in the range of 2 to 3 times the internal diameter of this hollow discharge part, The film-forming apparatus characterized by the above-mentioned. In the film-forming apparatus of Claim 8 or 9,
The through hole has a buffer portion for promoting the reaction of the source gas on at least one of the first electrode side and the opposite side of the first electrode in the hollow discharge portion of the through hole. A characteristic film forming apparatus. In the film-forming apparatus of Claim 10,
The film formation apparatus, wherein the through hole has the buffer section on the first electrode side and the opposite side of the first electrode in a hollow discharge section of the through hole.

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