JP2016015429A - Flange for plasma cavity, plasma cavity, and plasma cvd apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a flange for a plasma cavity capable of effectively introducing phosphorus (P) in a material gas into a diamond film, a plasma cavity, and a plasma CVD apparatus.SOLUTION: The flange for a plasma cavity of a substantially disc shape whose outer peripheral side face part is of a micro wave reflection shape is provided with a gas exhaust region of a ring shape in a plan view so as to surround a substrate arrangement region. In the gas exhaust region, 6 or more holes of a circular shape in a plan view are provided. Diameters of the holes are equal to or less than 6 mm, and are provided in point symmetry to a substrate center point. Intervals between the centers of the neighboring holes are equal to or larger than 5.5 mm.

Description

The present invention relates to a flange for a plasma cavity, a plasma cavity, and a plasma CVD apparatus.

  In recent years, diamond has attracted attention as a material for various electronic devices such as transistors, deep ultraviolet light emitting / receiving elements, and electron emitters. In particular, it is attracting attention as a power semiconductor material because it is stable at high voltage.

It has been studied to prepare a p-type or n-type diamond semiconductor by doping impurities into diamond. For example, there are reports of p-type diamond semiconductors (Patent Documents 1 to 3) and n-type diamond semiconductors (Patent Documents 4 to 6). By combining p-type and n-type diamond semiconductors, a pn device or a pin device made of only diamond can be produced.

Usually, plasma CVD is used to produce n-type or p-type diamond by controlling the doping amount of n-type or p-type impurities when vapor-depositing diamond.
In this method, it is easy to dope a p-type impurity such as boron (B) into diamond, but it is difficult to dope an n-type impurity such as phosphorus (P) into diamond.

Phosphorus (P) in the raw material gas that could not be doped adhered to the inner wall surface of the chamber of the apparatus and contaminated the chamber. This contamination deteriorated the purity of the diamond semiconductor and deteriorated the semiconductor characteristics. Therefore, a cleaning process for completely removing the dirt on the inner wall surface of the chamber was required, which deteriorated the production process.

As for the plasma CVD apparatus, a high energy injection method using a low or medium current type injection apparatus and an apparatus corresponding thereto are disclosed. Although it is a structure provided with a plasma cavity and a fixed flange, the said subject cannot be solved even with this structure (patent document 7).

JP 2013-67541 A JP 2011-225440 A JP 2006-173313 A JP 2013-67541 A JP 2011-225440 A JP2011-176360A Japanese National Patent Publication No. 8-511658

An object of the present invention is to provide a flange for a plasma cavity, a plasma cavity, and a plasma CVD apparatus that can introduce phosphorus (P) in a source gas into a diamond film with high efficiency.

In view of the above circumstances, the present inventor paid attention to the gas flow in the plasma cavity by trial and error, and the flange on which the substrate is disposed, which is disposed below the plasma cavity. A ring-shaped gas discharge region is formed so as to surround the central substrate arrangement region as closely as possible, and a plurality of circular holes in plan view are formed in the gas discharge region, so that the plasma cavity is directed toward the substrate from above. When the ejected gas hits the surface of the substrate, it is quickly discharged from the hole to the outside of the plasma cavity, and when diamond is formed on the substrate, phosphorus (P) in the source gas efficiently enters the film. In addition, since the interval between the center points of adjacent holes is at least 5.5 mm or more, the rigidity of the flange is ensured, and the substrate Since the film can be kept stable and the uniformity of the film can be improved, phosphorus (P) in the source gas can be efficiently doped into diamond, and an n-type diamond layer with reduced resistance can be obtained. The present invention has been completed by finding that it can be formed to produce a highly efficient diamond semiconductor electronic device.
The present invention has the following configuration.

(1) A substantially disc-shaped flange for a plasma cavity, the outer peripheral side surface portion of which is a microwave reflecting shape in which two disc members are arranged to face each other through a space portion. A circular area in plan view with the center in plan view of the member as the substrate center point is a substrate arrangement area, and a gas discharge area in a ring shape in plan view is provided so as to surround the substrate arrangement area. 6 or more circular holes in plan view are provided in the region, the diameter of the hole is 6 mm or less, provided symmetrically with respect to the center point of the substrate, and adjacent holes The plasma cavity flange is characterized in that the distance between the center points is at least 5.5 mm.

(2) The plasma cavity flange according to (1), wherein a plurality of holes are provided so that the center of the hole is positioned on a concentric circle of 22 mm or more and 24 mm or less from the center of the disk plane.
(3) The plasma according to (1) or (2), wherein a plurality of holes are provided so that the hole center is located on a concentric circle of 19 mm or more and 20 mm or less from the center of the disk plane. Flange for cavity.
(4) In any one of (1) to (3), a plurality of holes are provided so that the center of the hole is located on a concentric circle not less than 27 mm and not more than 29 mm from the center of the disk plane. The flange for a plasma cavity as described.

(5) A plasma cavity having a cylindrical container, wherein an opening on one end side of the cylindrical container is blocked by a quartz window plate, and an injection port is provided in the vicinity of the opening. (1) to (1) to (1) to (1) to the opening on the other end side so that one surface of one disk member is perpendicular to the axial direction of the cylindrical container and the outer peripheral side surface is separated from the inner wall of the cylindrical container. 4) A plasma cavity, wherein the plasma cavity flange according to any one of 4) is disposed.

(6) A film forming chamber having an opening, a lid plate that closes the opening, a gas introduction pipe attached to the lid plate, one surface of the lid plate and the axial direction of the cylindrical container are perpendicular to each other, A quartz window plate is fitted to the lid plate and attached to the lid plate, the plasma cavity according to (5), a microwave introduction tube having one end connected to the quartz window plate, and the microwave introduction tube A plasma CVD apparatus, comprising: a microwave generator connected to an end side; and a gas exhaust pipe attached in the vicinity of the opposite side of the opening of the film forming chamber.

The flange for a plasma cavity according to the present invention is a substantially disk-shaped flange for a plasma cavity, and has an outer peripheral side surface formed into a microwave reflection shape in which two disk members are arranged facing each other through a space portion. A planar view circular region having the center of the planar view of one disk member as a substrate center point is a substrate placement region, and a ring-shaped gas discharge region in plan view is provided so as to surround the substrate placement region. 6 or more circular holes in plan view are provided in the gas discharge region, the diameter of the holes is 6 mm or less, and is provided point-symmetrically with respect to the substrate center point; And since it is the structure by which the center point space | interval of the adjacent hole part is made into at least 5.5 mm or more, the phosphorus (P) in source gas can be introduce | transduced in a diamond film with high efficiency.

The plasma cavity of the present invention is a plasma cavity having a cylindrical container, the opening on one end side of the cylindrical container is blocked by a quartz window plate, and an injection port is provided in the vicinity of the opening, In the opening on the other end side of the cylindrical container, the outer peripheral side surface part is spaced apart from the inner wall of the cylindrical container so that one surface of one disk member is perpendicular to the axial direction of the cylindrical container. Therefore, the phosphorus (P) in the raw material gas can be introduced into the diamond film with high efficiency.

The plasma CVD apparatus of the present invention includes a film forming chamber having an opening, a lid plate that closes the opening, a gas introduction pipe attached to the lid plate, one surface of the lid plate, and an axial direction of the cylindrical container The quartz cavity is fitted to the lid plate, the plasma cavity is attached to the lid plate, the microwave introduction tube having one end connected to the quartz window plate, and the microwave introduction Since the microwave generator connected to the other end of the tube and the gas exhaust pipe attached in the vicinity of the opposite side of the opening of the film forming chamber, phosphorus (P) in the source gas is increased. It can be efficiently introduced into the diamond film.

It is the schematic which shows an example of the plasma CVD apparatus which is embodiment of this invention, Comprising: It is the whole schematic diagram (a) and the internal structure figure (b) of a cover plate. It is the schematic which shows an example of the plasma cavity which is embodiment of this invention. It is the schematic which shows an example of the flange for plasma cavities which is embodiment of this invention, Comprising: It is a top view (a) and a side view (b). It is explanatory drawing which shows an example of the flow of the source gas in a plasma cavity, Comprising: When the flange for plasma cavities which is embodiment of this invention is used (a), and the case where a conventional flange is used (b) . It is the schematic which shows another example of the flange for plasma cavities which is embodiment of this invention. It is the schematic which shows another example of the flange for plasma cavities which is embodiment of this invention. It is the schematic which shows another example of the flange for plasma cavities which is embodiment of this invention. It is the schematic which shows another example of the flange for plasma cavities which is embodiment of this invention. It is the schematic which shows another example of the flange for plasma cavities which is embodiment of this invention. It is the schematic which shows another example of the flange for plasma cavities which is embodiment of this invention. It is a top view of the produced stage (choke flange) of Example 1. FIG. It is a graph which shows the SIMS measurement result of the obtained diamond thin film. 6 is a plan view of a stage of Example 2. FIG. It is a graph which shows the SIMS measurement result of the obtained diamond thin film. It is a graph showing a PH ₃ concentration relationship of the phosphorus-doped diamond phosphorus concentration and the raw material gas in the film. 6 is a plan view of a stage (choke flange) of Comparative Example 1. FIG. It is a graph which shows the SIMS measurement result of the obtained diamond thin film. It is a graph which shows the relationship between the row number of a through-hole, and phosphorus (P) taking-in efficiency.

(Plasma CVD equipment)
First, a plasma CVD apparatus according to an embodiment of the present invention will be described.
FIG. 1 is a schematic diagram illustrating an example of a plasma CVD apparatus according to an embodiment of the present invention, which is an overall schematic diagram (a) and an internal structure diagram (b) of a cover plate.
A plasma CVD apparatus 1 according to an embodiment of the present invention is an end launch microwave plasma CVD apparatus.
As shown in FIG. 1A, a plasma CVD apparatus 1 according to an embodiment of the present invention includes a film forming chamber 28 provided with an opening 28a, a cover plate 18 that closes the opening 28a, and a cover plate 18. The attached gas introduction pipe (Gas inlet) 17, the one surface of the cover plate 18 and the axial direction of the cylindrical container 30 are perpendicular to each other, and a quartz window plate (Quartz window) 36 is fitted to the cover plate 18 and attached to the cover plate 18. A plasma cavity 29, a microwave introduction tube 15 connected at one end to the quartz window plate 36, a microwave generator 11 connected to the other end of the microwave introduction tube 15, and A gas exhaust pipe attached in the vicinity of the opposite side of the opening of the film forming chamber.

The film forming chamber 28 has a hollow portion 28c communicating with the opening 28a. A plasma cavity 29 is held in the cavity 28c.
A load lock chamber 19 is connected to the cavity 28 c of the film forming chamber 28 via a gate valve 25.

With the gate valve 25 closed, the inside is evacuated by a turbo molecular pump (not shown) connected to the gas exhaust pipe, so that the inside can be depressurized to about 2 × 10 ¹⁰ Torr. . The load lock chamber 19 can also be reduced in pressure to about 2 × 10 ¹⁰ Torr by a turbo molecular pump (not shown) through another exhaust pipe (Exhaust) 26.

A substrate holder 33 is installed on the plasma cavity flange 31, and a substrate 34 can be disposed on the substrate holder 33.

A horizontal movement rod (Transfer rod) 27 that is movable in the horizontal direction is attached to the load lock chamber 19.
Further, the plasma cavity flange 31 is supported by a vertical moving rod 32 that is movable in a vertical direction (Liner motion).

The gate valve 25 is opened in a state where the plasma cavity flange 31 is lowered by the vertical moving rod 32, and the substrate attached to the horizontal moving rod 27 is moved in the horizontal direction to the substrate holder 33 on the plasma cavity flange 31. Can be installed. Thereafter, the substrate can be placed at a predetermined position in the plasma cavity by pulling back the horizontal moving rod 27, closing the gate valve, and raising the vertical moving rod 32.

As shown in FIG. 1B, the gas introduction pipe 17 is connected to a ring-shaped pipe 17c provided with eight injection ports 37. Eight source gas injection ports 37 directed in the substrate direction are provided so as to be point symmetric at equal intervals. Thereby, source gas can be injected toward a substrate direction. The injected source gas passes through the plasma cavity 29 and is exhausted to the outside through the gas exhaust pipe 23 from the cavity 28 c of the film forming chamber 28.

The source gas passes through the gas introduction pipe 17 and enters the ring-shaped pipe 17c. The ring-shaped tube 17c is completely built in the cover plate 18 along the circumference of the cover plate 18. From this ring-shaped tube 17c, eight introduction lines are further extended to the inner wall of the cavity cylinder 30 to form eight injection ports 37 on the inner wall of the cavity.

The microwave introduction tube 15 is provided with a TE-TM mode converter. The microwave generated by the microwave generator 11 is controlled by the tuner 12 and moves in the microwave introduction tube 15 to convert the TE mode of the microwave into the TM mode, and passes through the quartz window 36. And introduced into the plasma cavity 29. Thereby, plasma 35 can be generated in the plasma cavity 29.

A radiation thermometer (Radiation thermometer) 14 can observe the state of the plasma 35 in the plasma cavity 29 via the prism 13 and the quartz window 36.

(Plasma cavity)
Next, the plasma cavity which is an embodiment of the present invention will be described.
FIG. 2 is a schematic view showing an example of a plasma cavity according to an embodiment of the present invention.
As shown in FIG. 2, the plasma cavity 29 according to the embodiment of the present invention is a plasma cavity having a cylindrical container 30, and an opening on one end side of the cylindrical container 30 is blocked by a quartz window plate 36. An injection port 37 is provided in the vicinity of the opening, so that one surface of one disk member is perpendicular to the axial direction of the cylindrical container 30 in the opening on the other end side of the cylindrical container 30 and A plasma cavity flange 31 is arranged with the outer peripheral side face away from the inner wall of the cylindrical container 30.

(Plasma cavity flange)
First, a plasma cavity flange according to an embodiment of the present invention will be described.
Drawing 3 is a schematic diagram showing an example of a flange for plasma cavities which is an embodiment of the present invention, and is a top view (a) and a side view (b).
As shown in FIG.3 (b), the flange 31 for plasma cavities which is embodiment of this invention is a flange for plasma cavities of a substantially disc shape. The outer peripheral side surface portion 41 has a microwave reflection shape in which two disk members 41a and 41b are arranged to face each other through a space portion. The plasma cavity flange 31 is supported by a vertical moving rod 32 and is movable up and down.

As shown in FIG. 3A, a planar view circular region having the center in plan view of one disk member 41 a as the substrate center point O is a substrate placement region 43, and surrounds the substrate placement region 43. A gas discharge region 44 having a ring shape in plan view is provided. A substrate holder 33 is installed in the substrate placement region 43.

Six or more circular holes 45 in plan view are provided in the gas discharge region 44.
The diameter of the hole 45 is 6 mm or less. Thereby, the microwave can be confined in the plasma cavity. If it exceeds 6 mm, the microwave may not be confined.

The hole 45 is provided point-symmetrically with respect to the substrate center point O. Thereby, it is possible to make isotropic flow of the gas discharged to the outside in front of the substrate and to uniformly dope phosphorus (P) in the plane. When not subject to a point object, the in-plane distribution of P may be non-uniform.

Further, the center point interval d45 between the adjacent holes 45 is at least 7.5 mm or more. Thereby, the rigidity of the flange can be ensured, the substrate can be kept stable, and the uniformity of the film can be improved.
For example, 16 hole portions 45 are provided at equal intervals of 22.5 ° so that the center of the hole portion is located on a concentric circle of 19 mm or more and 20 mm or less from the center of the disk plane.

With the above configuration, microwaves can be confined efficiently. Further, phosphorus (P) in the source gas can be efficiently taken into the film. Further, the rigidity of the flange can be secured, the substrate 34 can be kept stable, and the uniformity of the diamond film can be improved.

FIG. 4 is an explanatory view showing an example of the flow of the source gas in the plasma cavity. When the flange for plasma cavity according to the embodiment of the present invention is used (a) and when the conventional flange is used ( b).
The source gas G ejected from the plurality of ejection ports 37 of the plasma cavity 29 reacts with the plasma 35 and is deposited on the substrate 34 to form a diamond film. At this time, the raw material gas G not involved in the reaction is efficiently discharged from the hole 45 provided in the flange 31 for the plasma cavity. By controlling the flow of the source gas G in this way, it is possible to efficiently take in impurities and form a diamond thin film. Note that the source gas G is slightly discharged also from the gap between the outer peripheral side surfaces of the plasma cavity flange 31, but the flow of the source gas G is hardly affected.

For comparison, the flow of the source gas G when using a conventional flange in which no hole is formed will be described. The source gas G is ejected in the direction of the substrate 34, but after reacting with the plasma 35, the source gas G flows in the direction of the wall surface and is discharged only from the gaps on the outer peripheral side surface of the flange. For this reason, the source gas G cannot be efficiently flowed over the substrate 34, the substrate growth is slowed, and the impurity incorporation efficiency is also lowered.

FIG. 5 is a schematic view showing another example of a flange for a plasma cavity which is an embodiment of the present invention.
A plurality of holes are provided so that the hole center is located on a concentric circle of 22 mm or more and 24 mm or less from the center of the disk plane.
A gas discharge region 54 having a ring shape in plan view is provided so as to surround the substrate arrangement region 53, and microwaves are confined efficiently by a configuration in which six or more hole portions 55 having a circular shape in plan view are provided in the gas discharge region 54. be able to. Further, phosphorus (P) in the source gas can be efficiently taken into the film.
Further, the center point interval d55 between the adjacent holes 55 is at least 8.9 mm. The rigidity of the flange can be secured, the substrate can be kept stable, and the uniformity of the diamond film can be improved.

FIG. 6 is a schematic view showing another example of a flange for a plasma cavity which is an embodiment of the present invention.
A plurality of holes are provided so that the hole center is also located on a concentric circle of 27 mm or more and 29 mm or less from the center of the disk plane.
A gas discharge region 64 having a ring shape in plan view is provided so as to surround the substrate arrangement region 63, and microwaves are efficiently confined by a configuration in which six or more hole portions 65 having a circular shape in plan view are provided in the gas discharge region 64. be able to. Further, phosphorus (P) in the source gas can be efficiently taken into the film.
Further, the center point interval d65 between the adjacent holes 65 is at least 10.9 mm. The rigidity of the flange can be secured, the substrate can be kept stable, and the uniformity of the diamond film can be improved.

FIG. 7 is a schematic view showing another example of a flange for a plasma cavity which is an embodiment of the present invention.
A plurality of holes are provided so that the hole center is located on a concentric circle of 19 mm or more and 20 mm or less from the center of the disk plane, and the hole center is located on a concentric circle of 22 mm or more and 24 mm or less from the center of the disk plane. A plurality of holes are provided as described above.
A gas discharge region 74 having a ring shape in plan view is provided so as to surround the substrate arrangement region 73, and the microwave is efficiently confined by a configuration in which six or more hole portions 75 having a circular shape in plan view are provided in the gas discharge region 74. be able to.
Further, the center point interval d75 between the adjacent holes 75 is at least 5.5 mm or more. Phosphorus (P) in the source gas can be efficiently taken into the film. Further, the rigidity of the flange can be secured, the substrate can be kept stable, and the uniformity of the diamond film can be improved.

FIG. 8 is a schematic view showing another example of a flange for a plasma cavity which is an embodiment of the present invention.
A plurality of holes are provided so that the hole center is located on a concentric circle of 19 mm or more and 20 mm or less from the center of the disk plane, and the hole center is located on a concentric circle of 27 mm or more and 29 mm or less from the center of the disk plane. A plurality of holes are provided as described above.
A gas discharge region 84 having a ring shape in plan view is provided so as to surround the substrate arrangement region 83, and the microwave is efficiently confined by a configuration in which six or more holes 85 having a circular shape in plan view are provided in the gas discharge region 84. be able to.
Further, the center point interval d85 between the adjacent holes 85 is at least 7.5 mm or more. Phosphorus (P) in the source gas can be efficiently taken into the film. Further, the rigidity of the flange can be secured, the substrate can be kept stable, and the uniformity of the diamond film can be improved.

FIG. 9 is a schematic view showing another example of a flange for a plasma cavity which is an embodiment of the present invention.
A plurality of holes are provided so that the hole center is located on a concentric circle of 22 mm or more and 24 mm or less from the center of the disk plane, and the hole center is located on a concentric circle of 27 mm or more and 29 mm or less from the center of the disk plane. A plurality of holes are provided as described above.
A gas discharge region 94 having a ring shape in plan view is provided so as to surround the substrate arrangement region 93, and the microwave is efficiently confined by a configuration in which six or more hole portions 95 having a circular shape in plan view are provided in the gas discharge region 94. be able to.
Further, the center point interval d95 between the adjacent holes 95 is at least 7.0 mm or more. Phosphorus (P) in the source gas can be efficiently taken into the film. Further, the rigidity of the flange can be secured, the substrate can be kept stable, and the uniformity of the diamond film can be improved.

FIG. 10 is a schematic view showing still another example of the plasma cavity flange according to the embodiment of the present invention.
A plurality of holes are provided so that the hole center is located on a concentric circle of 19 mm or more and 20 mm or less from the center of the disk plane, and the center of the hole is positioned on a concentric circle of 22 mm or more and 24 mm or less from the center of the disk plane. The plurality of hole portions are provided, and the plurality of hole portions are provided so that the center of the hole portion is located on a concentric circle of 27 mm or more and 29 mm or less from the center of the disk plane.
A gas discharge region 104 having a ring shape in plan view is provided so as to surround the substrate arrangement region 103, and the microwave is efficiently confined by a configuration in which six or more hole portions 105 having a circular shape in plan view are provided in the gas discharge region 104. be able to.
Further, the center point interval d105 between adjacent hole portions 105 is at least 5.5 mm or more. Phosphorus (P) in the source gas can be efficiently taken into the film. Further, the rigidity of the flange can be secured, the substrate can be kept stable, and the uniformity of the diamond film can be improved.

The plasma cavity flanges 31, 51, 61, 71, 81, 91, 101 according to the embodiment of the present invention are substantially disk-shaped flanges for plasma cavities, and the outer peripheral side surface 41 has two disks. The members 41a and 41b have a microwave reflection shape arranged facing each other through a space portion, and a planar view circular region having the center of the planar view of one disk member 41a as a substrate center point is a substrate placement region 43, 53, 63, 73, 83, 93, 103, and gas discharge areas 44, 54, 64, 74, 84, 94, 104 in a ring shape in plan view are provided so as to surround the substrate arrangement area. 6 or more circular holes 45, 55, 65, 75, 85, 95, 105 in plan view are provided in the gas discharge region, and the diameter of the holes is 6 mm or less, and the substrate center point Symmetric with respect to O And the center point distances d45, d55, d65, d75, d85, d95, and d105 between adjacent holes are at least 5.5 mm or more, so the flow of gas passing through the substrate surface is reduced. It can be controlled to increase, and phosphorus (P) in the source gas can be introduced into the diamond film with high efficiency.

The plasma cavity flanges 51, 71, 91, 101 according to the embodiment of the present invention are provided with a plurality of holes so that the hole centers are located concentrically between 22 mm and 24 mm from the center of the disk plane. Due to the configuration, phosphorus (P) in the source gas can be introduced into the diamond film with high efficiency.

The plasma cavity flanges 31, 71, 81, 101 according to the embodiment of the present invention are provided with a plurality of holes so that the hole centers are also located on concentric circles of 19 mm or more and 20 mm or less from the center of the disk plane. Therefore, phosphorus (P) in the source gas can be introduced into the diamond film with high efficiency.

The plasma cavity flanges 61, 81, 91, 101 according to the embodiment of the present invention are provided with a plurality of holes so that the hole center is also located on a concentric circle of 27 mm to 29 mm from the center of the disk plane. Therefore, phosphorus (P) in the source gas can be introduced into the diamond film with high efficiency.

The plasma cavity 29 according to the embodiment of the present invention is a plasma cavity having a cylindrical container 30, and an opening on one end side of the cylindrical container is blocked by a quartz window plate 36, and is injected near the opening. An opening 37 is provided, and an opening on the other end side of the cylindrical container is provided so that one surface of one disk member 41a is perpendicular to the axial direction of the cylindrical container and from the inner wall of the cylindrical container Since the plasma cavity flange 31 described above is disposed with the outer peripheral side surface portion 41 spaced apart, it can be controlled to increase the flow of gas passing through the substrate surface, and phosphorus (P) in the source gas can be controlled. Can be introduced into the diamond film with high efficiency.

A plasma CVD apparatus 1 according to an embodiment of the present invention includes a film forming chamber 28 provided with an opening 28a, a cover plate 18 that closes the opening, a gas introduction pipe 17 attached to the cover plate, and the cover plate. A microwave window 36 is fitted with a quartz window plate 36 fitted to the lid plate, and one end side of the quartz window plate is connected to the quartz window plate. Since the microwave generator 11 connected to the other end of the microwave introduction tube and the gas exhaust pipe 23 attached in the vicinity of the opposite side of the opening of the film forming chamber, The flow of gas passing through the substrate surface can be controlled to increase, and phosphorus (P) in the source gas can be introduced into the diamond film with high efficiency.

The flange for a plasma cavity, the plasma cavity, and the plasma CVD apparatus according to the embodiment of the present invention are not limited to the above embodiment, and can be implemented with various modifications within the scope of the technical idea of the present invention. it can. Specific examples of this embodiment are shown in the following examples. However, the present invention is not limited to these examples.

(Example 1)
<Stage (choke flange) production>
First, the stage (choke flange) of Example 1 was produced. At a position on a concentric circle of 23 mm from the center of the disk plane of the stage (choke flange), a through hole having a diameter of 6 mm is set to be a point object at the center point so that the through hole: gap area ratio = 1: 1. 16 were opened to produce the stage (choke flange) of Example 1. The gap area is the area of the gap in plan view between the outer peripheral side surface portion and the cylindrical inner wall.
FIG. 11 is a plan view of the produced stage (choke flange) of Example 1. FIG.

<Preparation of phosphorus-doped n-type diamond CVD thin film>
A phosphorus-doped n-type diamond CVD thin film was prepared as follows.
First, the stage of Example 1 was placed under the plasma cavity inside the chamber of the unique end launch type microwave plasma CVD apparatus shown in the embodiment of the present invention.
Next, the inside of the chamber was evacuated by a turbo molecular pump, and the pressure was reduced to about 2 × 10 ¹⁰ Torr.
Next, the stage of Example 1 was lowered by the vertical movement bar.
Next, the gate valve was opened, and the Ib type diamond {111} substrate placed in the load lock chamber was set on the substrate placement portion of the stage (choke flange) with a horizontal moving rod.
Next, the stage of Example 1 was raised and the substrate was placed at a predetermined position in the plasma cavity.

Next, from a port having a diameter of 2 mm, which is isotropically disposed at eight locations on the plasma cavity, the raw material gas is at a pressure of 100 Torr, the methane concentration CH ₄ / H ₂ is 0.05%, and the H ₂ dilution PH ₃ (dilution) The rate PH ₃ / H ₂ concentration ratio 100 ppm) was used, the phosphorus concentration in the source gas (PH ₃ / CH ₄ concentration ratio) was set to 100 ppm, and the source gas was introduced and discharged from the lower part.

Next, microwaves were emitted to generate plasma in the plasma cavity, and the microwave output was adjusted so that the substrate temperature was 915 to 930 ° C., and a phosphorus-doped diamond thin film was synthesized on the substrate surface.

FIG. 12 is a graph showing the SIMS measurement results of the obtained diamond thin film. From FIG. 12, the phosphorus (P) concentration in diamond was 8 × 10 ¹⁶ cm ⁻³ .
Since gas was discharged not only through the gap between the inner wall of the choke flange and the cavity, but also through the through-hole, the efficiency of taking in phosphorus (P) in the raw material gas was 0.47%.

(Example 2)
<Stage (choke flange) production>
Next, the stage (choke flange) of Example 2 was produced.
First, 16 through-holes having a diameter of 6 mm were formed at positions on a concentric circle 23 mm from the center of the disk plane of the stage (choke flange) so as to be pointed at the center point of the substrate.
Next, 16 through-holes with a diameter of 4 mm were formed at positions on a concentric circle of 19.25 mm from the center of the disk so as to be pointed at the center point of the substrate.
Next, 16 through-holes with a diameter of 6 mm were formed at positions on a concentric circle of 23 mm from the center of the disk so as to be pointed at the center point of the substrate.
The total area of the through holes: gap area ratio = 2: 1.
Thus, the stage (choke flange) of Example 2 was produced.
FIG. 13 is a plan view of the stage of the second embodiment.

<Preparation of phosphorus-doped n-type diamond CVD thin film>
Next, a phosphorus-doped n-type diamond CVD thin film was synthesized in the same manner as in Example 1 except that the stage of Example 2 was used.

FIG. 14 is a graph showing SIMS measurement results of the obtained diamond thin film. From FIG. 14, the phosphorus (P) concentration in the diamond was 8.5 × 10 ¹⁷ cm ⁻³ .
Since the gas was discharged not only through the gap between the choke flange and the inner wall of the cavity, but also through the through hole, the efficiency of taking in phosphorus (P) in the raw material gas was 5%.

(Example 2-2)
Next, a phosphorus-doped n-type diamond CVD thin film was synthesized in the same manner as in Example 2 except that the PH ₃ concentration in CH ₄ gas was 400 ppm. From the SIMS measurement, the phosphorus (P) concentration in the diamond thin film was 2.3 × 10 ¹⁸ cm ⁻³ . The efficiency of taking in phosphorus (P) in the raw material gas was 3.27%.

(Example 2-3)
Next, a phosphorus-doped n-type diamond CVD thin film was synthesized in the same manner as in Example 2 except that the PH ₃ concentration in CH ₄ gas was 400 ppm. From the SIMS measurement, the phosphorus (P) concentration in the diamond thin film was 7.1 × 10 ¹⁸ cm ⁻³ . The efficiency of taking in phosphorus (P) in the raw material gas was 10.1%.

(Example 2-4)
Next, a phosphorus-doped n-type diamond CVD thin film was synthesized in the same manner as in Example 2 except that the PH ₃ concentration in the CH ₄ gas was 1000 ppm. From the SIMS measurement, the phosphorus (P) concentration in the diamond thin film was 1.1 × 10 ¹⁹ cm ⁻³ . The efficiency of taking in phosphorus (P) in the raw material gas was 6.25%.

(Example 2-5)
Next, a phosphorus-doped n-type diamond CVD thin film was synthesized in the same manner as in Example 2 except that the PH ₃ concentration in the CH ₄ gas was 1000 ppm. From the SIMS measurement, the phosphorus (P) concentration in the diamond thin film was 1.4 × 10 ¹⁹ cm ⁻³ . The efficiency of taking in phosphorus (P) in the raw material gas was 7.95%.

(Example 2-6)
Next, a phosphorus-doped n-type diamond CVD thin film was synthesized in the same manner as in Example 2 except that the PH ₃ concentration in CH ₄ gas was set to 4000 ppm. From the SIMS measurement, the phosphorus (P) concentration in the diamond thin film was 5.4 × 10 ¹⁹ cm ⁻³ . The efficiency of taking in phosphorus (P) in the raw material gas was 7.67%.

(Example 2-7)
Next, a phosphorus-doped n-type diamond CVD thin film was synthesized in the same manner as in Example 2 except that the PH ₃ concentration in CH ₄ gas was set to 4000 ppm. From the SIMS measurement, the phosphorus (P) concentration in the diamond thin film was 7.4 × 10 ¹⁹ cm ⁻³ . The efficiency of taking in phosphorus (P) in the raw material gas was 10.5%.

(Example 2-8)
Next, a phosphorus-doped n-type diamond CVD thin film was synthesized in the same manner as in Example 2 except that the PH ₃ concentration in CH ₄ gas was 100 ppm. From the SIMS measurement, the phosphorus (P) concentration in the diamond thin film was 5.5 × 10 ¹⁷ cm ⁻³ . The efficiency of taking in phosphorus (P) in the raw material gas was 3.13%.

(Example 2-9)
Next, a phosphorus-doped n-type diamond CVD thin film was synthesized in the same manner as in Example 2 except that the PH ₃ concentration in CH ₄ gas was 100 ppm. From the SIMS measurement, the phosphorus (P) concentration in the diamond thin film was 7 × 10 ¹⁷ cm ⁻³ . The efficiency of taking in phosphorus (P) in the raw material gas was 3.98%.

(Example 2-10)
Next, a phosphorus-doped n-type diamond CVD thin film was synthesized in the same manner as in Example 2 except that the PH ₃ concentration in the CH ₄ gas was 1000 ppm. From the SIMS measurement, the phosphorus (P) concentration in the diamond thin film was 5.8 × 10 ¹⁸ cm ⁻³ . The efficiency of taking in phosphorus (P) in the raw material gas was 3.3%.

(Example 2-11)
Next, a phosphorus-doped n-type diamond CVD thin film was synthesized in the same manner as in Example 2 except that the PH ₃ concentration in CH ₄ gas was 10,000 ppm. From the SIMS measurement, the phosphorus (P) concentration in the diamond thin film was 9 × 10 ¹⁹ cm ⁻³ . The efficiency of taking in phosphorus (P) in the raw material gas was 5.11%.

(Example 2-12)
Next, a phosphorus-doped n-type diamond CVD thin film was synthesized in the same manner as in Example 2 except that the PH ₃ concentration in CH ₄ gas was 10,000 ppm. From the SIMS measurement, the phosphorus (P) concentration in the diamond thin film was 6.5 × 10 ¹⁹ cm ⁻³ . The efficiency of taking in phosphorus (P) in the raw material gas was 3.69%.

(Example 2-13)
Next, a phosphorus-doped n-type diamond CVD thin film was synthesized in the same manner as in Example 2 except that the PH ₃ concentration in CH ₄ gas was 100 ppm. From the SIMS measurement, the phosphorus (P) concentration in the diamond thin film was 2 × 10 ¹⁷ cm ⁻³ . The efficiency of taking in phosphorus (P) in the raw material gas was 1.14%.

(Example 2-14)
Next, a phosphorus-doped n-type diamond CVD thin film was synthesized in the same manner as in Example 2 except that the PH ₃ concentration in CH ₄ gas was set to 4000 ppm. From the SIMS measurement, the phosphorus (P) concentration in the diamond thin film was 3.6 × 10 ¹⁹ cm ⁻³ . The efficiency of taking in phosphorus (P) in the raw material gas was 5.11%.

(Example 2-15)
Next, a phosphorus-doped n-type diamond CVD thin film was synthesized in the same manner as in Example 2 except that the PH ₃ concentration in the CH ₄ gas was 1000 ppm. From the SIMS measurement, the phosphorus (P) concentration in the diamond thin film was 8.8 × 10 ¹⁸ cm ⁻³ . The efficiency of taking in phosphorus (P) in the raw material gas was 5.18%.

FIG. 15 is a graph showing the relationship between the phosphorus concentration in the phosphorus-doped diamond thin film and the PH ₃ concentration in the source gas, summarizing (Example 2) and (Example 2-2) to (Example 2-15). is there. In the case of the through hole: gap area ratio = 2: 1, the phosphorus concentration in the diamond film increased almost proportionally as the PH ₃ concentration in the gas was changed from 100 ppm to 10,000 ppm.

(Comparative Example 1)
FIG. 16 is a plan view of the stage (choke flange) of Comparative Example 1. FIG.
A phosphorus-doped diamond thin film was synthesized in the same manner as in Example 1 except that a stage without a through hole (choke flange) (Comparative Example 1) was used.

FIG. 17 is a graph showing the SIMS measurement results of the obtained diamond thin film. From FIG. 17, the phosphorus (P) concentration in diamond was about 8 × 10 ¹⁵ cm ⁻³ .
Since the gas was discharged only through the gap between the inner walls of the choke flange and the cavity, the efficiency of taking in phosphorus (P) in the raw material gas was about 0.05%.

Next, based on the SIMS results of Comparative Example 1 and Examples 1 and 2-1, the relationship between the number of through-hole rows and phosphorus (P) uptake efficiency was summarized in a bar graph.
FIG. 18 is a graph showing the relationship between the number of rows of through holes and phosphorus (P) uptake efficiency.
Three rows showed high efficiency. That is, the higher the through hole: gap area ratio, the higher the efficiency.

(Test Example 1)
A simulation experiment of gas flow in the chamber was performed by the finite element method.
As a result of the simulation experiment, it was found that when the through hole exists in the choke flange, the gas flux in the portion reaching the substrate surface from the upper part of the cavity through the plasma region becomes large.

The gas flux from the upper part to the lower part is smoothed by the through hole by increasing the gas flux in the part that reaches the substrate surface through the plasma region, and the PH ₃ molecule is plasmad while suppressing the influence of convection due to the plasma heat. Can supply to the area. As a result, it was presumed that the vapor phase species containing the dopant was promoted to reach the substrate surface, and the efficiency of incorporating phosphorus atoms into the diamond film was improved.

The flange for a plasma cavity, the plasma cavity and the plasma CVD apparatus of the present invention can introduce phosphorus (P) in a source gas into a diamond film with high efficiency, so that it is used in the diamond semiconductor manufacturing industry, the power device manufacturing industry, etc. there is a possibility.

DESCRIPTION OF SYMBOLS 1 ... Plasma CVD apparatus, 11 ... Microwave generator, 12 ... Tuner, 13 ... Prism, 14 ... Radiation thermometer, 15 ... Microwave introduction pipe, 17 ... Gas introduction pipe, 17c ... Ring-shaped pipe, 18 ... Lid, 19 ... Load lock chamber, 23 ... Gas exhaust pipe, 25 ... Gate valve, 26 ... Gas exhaust pipe, 27 ... Horizontal moving rod, 28 ... Deposition chamber, 28a ... Opening, 28c ... Cavity, 29 DESCRIPTION OF SYMBOLS ... Plasma cavity, 30 ... Cylindrical container, 31 ... Flange for plasma cavity, 32 Vertical movement rod, 33 ... Substrate holder, 34 ... Substrate, 35 ... Plasma, 36 ... Quartz window part, 37 ... Injection port, 41 ... Outer peripheral side part , 41a ... disc member, 41b ... disc member, 43 ... substrate placement region, 44 ... gas discharge region, 45 ... hole, 51 ... outer peripheral side portion, 53 ... substrate placement region, 54 Gas discharge region, 55 ... hole, 61 ... outer peripheral side, 63 ... substrate placement region, 64 ... gas discharge region, 65 ... hole, 71 ... outer side surface, 73 ... substrate placement region, 74 ... gas discharge region, 75 ... Hole, 81 ... Outer peripheral side, 83 ... Substrate placement region, 84 ... Gas discharge region, 85 ... Hole, 91 ... Outer peripheral side, 93 ... Substrate placement region, 94 ... Gas discharge region, 95 ... Hole 101 ... Outer peripheral side surface, 103 ... Substrate arrangement region, 104 ... Gas discharge region, 105 ... Hole, G ... Source gas.

Claims (6)

A substantially disc-shaped flange for a plasma cavity,
The outer peripheral side surface has a microwave reflection shape in which two disk members are arranged to face each other via a space portion,
A planar view circular region having the center of the planar view of one disk member as the substrate center point is a substrate placement region,
A gas discharge region in a ring shape in plan view is provided so as to surround the substrate arrangement region,
6 or more circular holes in plan view are provided in the gas discharge region,
The hole has a diameter of 6 mm or less, is provided point-symmetrically with respect to the center point of the substrate, and the center point interval between adjacent holes is at least 5.5 mm or more. Flange for plasma cavity.   The flange for a plasma cavity according to claim 1, wherein a plurality of holes are provided so that the center of the hole is positioned on a concentric circle of 22 mm or more and 24 mm or less from the center of the disk plane.   The flange for a plasma cavity according to claim 1 or 2, wherein a plurality of holes are provided so that the center of the hole is also located on a concentric circle of 19 mm or more and 20 mm or less from the center of the disk plane.   The plasma according to any one of claims 1 to 3, wherein a plurality of holes are provided so that the center of the hole is positioned on a concentric circle of 27 mm or more and 29 mm or less from the center of the disk plane. Flange for cavity. A plasma cavity having a cylindrical container,
The opening on one end side of the cylindrical container is blocked with a quartz window plate,
An injection port is provided in the vicinity of the opening,
The opening on the other end side of the cylindrical container is such that one surface of one disk member is perpendicular to the axial direction of the cylindrical container, and the outer peripheral side surface is separated from the inner wall of the cylindrical container, Item 5. A plasma cavity, wherein the plasma cavity flange according to any one of Items 1 to 4 is disposed. A deposition chamber with an opening;
A lid plate that closes the opening;
A gas inlet pipe attached to the lid plate;
The plasma cavity according to claim 5, wherein one surface of the lid plate and the axial direction of the cylindrical container are perpendicular to each other, a quartz window plate is fitted to the lid plate, and the plasma cavity is attached to the lid plate.
A microwave introduction tube having one end connected to the quartz window plate;
A microwave generator connected to the other end of the microwave introduction tube;
A gas exhaust pipe attached in the vicinity of the opposite side of the opening of the film forming chamber;
A plasma CVD apparatus characterized by comprising: