JP2008255467A - Plasma cvd apparatus and film deposition method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To satisfactorily perform film deposition in a DC plasma CVD apparatus. <P>SOLUTION: A ring nozzle 22 having a plurality of ejection ports at equal intervals on an inner circumference is arranged in positions higher than the highest point of the positive column PC formed between an anode 11a and a cathode 13 within a chamber 10, and lower than the upper end face of the cathode 13, and reaction gases are horizontally ejected from the ring nozzle 22. Also, the reaction gases are exhausted from exhaust pipelines 20 evenly arranged on the surrounding of a stage 11 mounted with an anode 11a. As a result, the reaction gases are equally supplied to the front face of the substrate 10 and the film deposition can be satisfactorily performed. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a plasma CVD apparatus and a film forming method.

  In a CVD apparatus that deposits a film on a substrate by chemical vapor deposition (CVD), a matrix gas and a reaction gas, which is a raw material gas, are introduced into a reaction tank, and the pumping speed is balanced. This keeps the pressure in the reaction tank constant. In the plasma CVD apparatus that generates plasma, the gas temperature locally becomes high, so that turbulent gas flow occurs in the reaction vessel.

It is desirable that the gas containing the reaction gas flows slowly and uniformly toward the substrate surface on which the film grown by the reaction of the gas is deposited. If the flow is too fast, it causes uneven film formation, and the reaction gas It is known that the growth rate of the film is slowed if the vector in the moving direction is not directed to the substrate.
For example, Patent Documents 1 and 2 and Non-Patent Document 1 include conventional plasma CVD apparatuses aimed at eliminating unevenness of film formation and maintaining the growth rate.

Japanese Patent No. 2628404 JP-A-1-94615 Yoshiyuki Abe et al., “DIAMOND SYNTHESIS BY HIGH GRAVITY D.C. PLASMA CVD (HGCVD) WITH ACTIVE CONTROL OF THE SUBSTRATE TEMPERATURE”, Acta Astronautica (UK), 2001, Vol. 48, No. 2-3, p.121-127

  In the plasma CVD apparatus of Patent Document 1, a reaction gas is supplied from a direction parallel or inclined to the surface of the substrate, a matrix gas is supplied from a direction substantially perpendicular to the surface of the substrate, and the reaction gas is pressed by the matrix gas. Thus, the flow direction of the reaction gas is changed to spray the reaction gas onto the substrate surface.

  However, the plasma CVD apparatus of Patent Document 1 is a thermal plasma CVD apparatus that generates thermal plasma by heating a susceptor with a heater, and the electrode arrangement does not have to be a problem. However, when an electrode is disposed at a position facing the substrate as in a DC plasma CVD apparatus, the electrode becomes an obstacle, and it is difficult to create a uniform gas flow in a direction perpendicular to the substrate. .

  The plasma CVD apparatus of Patent Document 2 directly injects gas from a nozzle provided on a cathode (cathode) facing the substrate. Thereby, the reaction gas from the cathode to the substrate can flow.

  However, in this structure, when the plasma is generated, the active species due to the reactive gas are present at a high density in the nozzle portion of the cathode that becomes high temperature. For this reason, there is a problem in that deposits gradually accumulate in the nozzles opened in the cathode, thereby obstructing gas ejection. Further, if the deposit grows from the vicinity of the nozzle and becomes a protrusion, the electric field concentrates on the protrusion, and there is a risk that the plasma may shift to arc discharge or spark discharge. Furthermore, since a gas whose temperature is lowered due to room temperature or expansion is blown toward the plasma, there is a risk that the positive column is partially contracted to cause uneven film formation.

  In the plasma CVD apparatus of Non-Patent Document 1, a gas introduction port is provided in the upper part of the reaction tank, a gas exhaust port is provided below, and a gas flow from the cathode to the anode through the plasma is generated.

FIG. 31 is a diagram for explaining the flow of gas in the reaction tank of the plasma CVD apparatus of Non-Patent Document 1, in which FIG. 31 (a) shows the structure of the reaction tank, and FIG. The direction and flow rate of gas flow are indicated by arrows.
In the plasma CVD apparatus of Non-Patent Document 1, as shown in FIG. 31A, the position of the gas inlet GI and the gas outlet GO are on the opposite side across the central axis of the reaction vessel. Therefore, the gas toward the anode (Anode) is dominant near the lower part of the cathode (Cathode), but as shown in FIG. 3 (b), the convection gas on the gas inlet GI side and the convection on the gas outlet GO side. There is a temperature difference between the gas and the gas. The local pressure of the gas is also different.

  In the DC plasma CVD apparatus, the partial pressure state of each component in the active species as the film forming material differs depending on the gas temperature in the plasma, and if the temperature increases, the partial pressure value of the active species having a high chemical potential can be obtained. It becomes higher than the partial pressure value of the active species having a relatively low chemical potential. If the temperature in the reaction tank is different, the temperature of the gas in the plasma is uneven, so that the partial pressure of each active species is uneven depending on the location, and there is a risk that the film formation becomes uneven.

  As described above, the plasma CVD apparatus of Patent Document 1 is a thermal plasma CVD apparatus that generates thermal plasma by heating a susceptor with a heater, and an electrode is disposed at a position facing the substrate, like the DC plasma CVD apparatus. In this case, it has been difficult to create a uniform gas flow with respect to the substrate.

In addition, the plasma CVD apparatus of Patent Document 2 is not technically satisfactory because there is a possibility that the film CVD may be hindered and there is a risk of uneven film formation.
Further, the plasma CVD apparatus of Non-Patent Document 1 has incomplete uniformity of the gas supplied to the substrate.

  The present invention is an invention made in view of such a situation, and even when there is an electrode at a position facing the substrate, it is possible to supply the reaction gas almost uniformly to the substrate surface and to form a film well. An object is to provide a plasma CVD apparatus and a film forming method.

In order to achieve the above object, a plasma CVD apparatus according to the first aspect of the present invention comprises:
A first electrode disposed in the reaction vessel and on which the substrate is placed;
A second electrode facing the first electrode above the first electrode and generating plasma between the first electrode;
A region where plasma is generated between the first electrode and the second electrode and disposed between the first electrode and the second electrode in the reaction vessel. A first gas introduction nozzle formed with a plurality of jets arranged to surround
It is characterized by providing.

  Note that the first gas introduction nozzle may include a source gas in which active species are formed by the plasma.

  Further, the first gas introduction nozzle may include a source gas and a matrix gas in which active species are formed by the plasma.

  Moreover, it is preferable that the first gas introduction nozzle jets gas in the lateral direction from the plurality of jet nozzles toward the central axis of the first electrode.

  The first gas introduction nozzle is preferably arranged so as to surround the first electrode.

  Moreover, it is preferable that the plurality of jet nozzles of the first gas introduction nozzle are arranged at equal intervals.

  In addition, it is preferable that the plurality of jet nozzles of the first gas introduction nozzle have the same distance from the central axis of the first electrode.

  In addition, each set of jet nozzles composed of two of the plurality of jet nozzles of the first gas introduction nozzle may be disposed so as to face each other around the central axis of the first electrode. preferable.

  Moreover, it is preferable that the height of the jet port of the first gas introduction nozzle is higher than the highest point of the region where the positive column of the plasma is generated.

  The first gas introduction nozzle may be ring-shaped, or may be pipes facing each other along the side of the second electrode in the reaction vessel.

  Moreover, you may provide the 2nd gas introduction nozzle which ejects matrix gas toward the gas ejected from the said 1st gas introduction nozzle from the said 2nd electrode.

In addition, it is preferable to include a plurality of discharge conduits that are disposed below the first electrode and discharge gas from the reaction vessel.
In particular, the plurality of discharge conduits are preferably arranged so as to surround the first electrode.

  The second electrode is composed of a plurality of electrodes, and the voltage or current between each electrode of the second electrode and the first electrode may be individually set to an arbitrary value. Good.

  In this case, the plurality of electrodes includes a central electrode facing the central portion of the first electrode and a peripheral electrode facing the peripheral portion of the first electrode, and at the time of rising, the predetermined processing is performed. At the start, the voltage or current value between the central electrode and the first electrode may be set higher than the voltage or current value between the peripheral electrode and the first electrode.

The plurality of electrodes includes the central electrode facing a central portion of the first electrode and a peripheral electrode facing a peripheral portion of the first electrode, and the central electrode and the first electrode After a positive column is formed between the electrodes, the voltage or current value between the central electrode and the first electrode is less than the voltage or current value between the peripheral electrode and the first electrode. May be.
Moreover, it is preferable that an insulator is disposed between the plurality of electrodes.

  In order to achieve the above object, a film forming method according to a second aspect of the present invention generates a plasma by applying a voltage between a first electrode on which a substrate is placed and a second electrode. The reaction gas is ejected from a plurality of ejection ports arranged so as to surround the region.

  According to the present invention, good film formation can be achieved.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[First Embodiment]
FIG. 1 is a configuration diagram showing an outline of a plasma CVD apparatus according to the first embodiment of the present invention.

This DC plasma CVD apparatus is an apparatus that forms a film on the surface of a substrate 1 to be processed, and includes a chamber 10 that is a reaction tank. The chamber 10 blocks the substrate 1 from the outside air.
A cylindrical steel stage 11 is disposed in the chamber 10, and an anode 11 a made of, for example, molybdenum or graphite having a high thermal melting point and a high melting point is placed on the stage 11. Yes. The diameter of the anode 11a is, for example, 80 mm and the thickness is 20 mm. The substrate 1 is rectangular and is fixed to the upper mounting surface of the anode 11a. The stage 11 is set to rotate about the axis 11x together with the anode 11a.

  The stage 11 below the anode 11a is provided with a closed space 11b, and a cooling member 12 is disposed in the space 11b. The cooling member 12 is provided to cool the substrate 1 as necessary, and has a structure in which the cooling member 12 is movable up and down as indicated by an arrow by a moving mechanism (not shown). The cooling member 12 is formed of a metal having high thermal conductivity such as copper, and inside thereof, a cooling medium such as cooled water or a cooled aqueous solution of calcium chloride passes from the pipe 12a to the flow path 12b in the cooling member 12. It circulates so as to be discharged from the pipe 12c, and cools the entire cooling member 12.

For this reason, when the cooling member 12 moves upward, the upper surface 1 of the cooling member 12 contacts the lower surface of the stage 11, and the contacted stage 11 cools the upper anode 11 a, and the anode 11 a becomes the substrate 1. The structure that takes away the heat of. The cooling medium discharged from the pipe 12c is cooled by a cooling device (not shown) and circulated so as to be sent out again to the pipe 12a. The upper surface of the cooling member 12 is preferably slightly larger than the substrate 1 in order to cool the substrate 1 evenly in the surface direction.
In addition, a space 11b provided below the anode 11a is partitioned by the stage 11, and is filled with gas or opened to the atmosphere.

  A disc-shaped cathode 13 is disposed above the anode 11a. The cathode 13 is supported by the cathode support 14, and the cathode 13 and the anode 11a face each other. The cathode 13 is made of molybdenum or graphite having a high melting point, and has a diameter of 80 mm and a thickness of 20 mm, for example. The cathode support 14 is made of a heat-resistant oxide such as quartz glass or alumina, a heat-resistant nitride such as aluminum nitride or silicon nitride, or a heat-resistant carbide such as silicon carbide. The distance between the cathode 13 and the anode 11a is, for example, 50 mm.

  A flow path through which a cooling medium flows may be formed inside the cathode 13. When the cooling medium flows, overheating of the cathode 13 can be suppressed. As the cooling medium, water introduced from the outside of the chamber 10, a calcium chloride aqueous solution, or the like is preferable.

  An insulator 15 for suppressing arc generation is disposed in the vicinity of the outer peripheral surface of the anode 11a. The insulator 15 is made of at least one of a heat-resistant oxide such as quartz glass and alumina, a heat-resistant nitride such as aluminum nitride and silicon nitride, and a heat-resistant carbide such as silicon carbide.

  The insulator 15 has a ring shape and is supported at the same height as the anode 11a by a support 16 standing on the bottom of the chamber 10, and surrounds the outer periphery of the anode 11a on the inner peripheral side thereof. The outer diameter of the insulator 15 is at least 1.2 times the outermost diameter of the cathode 13.

  Since the insulator 15 suppresses the occurrence of abnormal discharge (arc discharge, spark discharge) between the cathode 13 and the anode 11a, the insulator 15 is placed facing the cathode 13 along the outer peripheral side surface of the anode 11a. Yes. The insulator 15 may hide the side surface of the anode 11 a from the cathode 13.

  A window 17 is formed on the side surface of the chamber 10 so that the inside of the chamber 10 can be observed. The window 17 is fitted with heat-resistant glass to ensure airtightness in the chamber 10. A radiation thermometer 18 that measures the temperature of the substrate 1 through, for example, the glass of the window 17 is disposed outside the chamber 10.

  In this DC plasma CVD apparatus, a source system (not shown) for introducing a source gas containing a reaction gas through a gas tube 19 and a gas are exhausted from the chamber 10 through a plurality of exhaust pipes 20 to form a chamber. 10 is provided with an exhaust system (not shown) that adjusts the atmospheric pressure in 10 and a voltage setting unit 21.

  The gas tube 19 is inserted into the chamber 10 through a hole provided in the chamber 10, and at least a part of the gas tube 19 in the reaction tank is made of an insulator such as fluororesin or silicon rubber. Yes. The space between the hole of the chamber and the outer periphery of the gas tube 19 is sealed with a sealing material to ensure the airtightness in the chamber 10. In the chamber 10, the gas tube 19 is connected to a ring nozzle 22 which is a gas introduction nozzle. The ring nozzle 22 is preferably a perfect circle, but may be a regular polygon.

FIG. 2 is an explanatory diagram of the ring nozzle 22 and the exhaust pipe 20.
The ring nozzle 22 has a ring shape as a whole and is hollow so that the source gas flows. On the ring-shaped inner peripheral surface side of the ring nozzle 22, a plurality of jet nozzles 22a having the same diameter are arranged at equal intervals. The plurality of jet nozzles 22a have the same distance from the axis 11x, which is the central axis of the anode 11a, and the individual jet nozzles 22a are such that the jet nozzles 22a face each other at opposite positions with the axis 11x as the center. It is provided symmetrically. Thus, as will be described later, the plurality of jet ports 22a are formed so as to surround a region where plasma is generated, and the source gas is jetted uniformly from the jet port 22a toward the shaft 11x.

The ring nozzle 22 is supported by an insulating nozzle support 23 attached to the cathode support 14. The jet nozzle 22a of the ring nozzle 22 is higher than the height of the anode 11a at a position below the lowermost portion of the cathode support 14 (the uppermost portion of the side surface exposed from the cathode support 14 of the cathode 13), and the anode 11a It is set at a position higher than the highest point of the positive column PC formed between the cathode 13. If the ring nozzle 22 is supported within this range, the source gas is likely to enter between the cathode 13 and the anode 11a, and the gas temperature in the positive column PC is prevented from being locally cooled by the ejection of the source gas. be able to.
The inner diameter of the ring nozzle 22 is larger than the outer diameter of the cathode 13 and the outer diameter of the anode 11a. The center of the ring nozzle 22 is on the axis 11x of the anode 11a. The angles sandwiching each jet port 22a from the center of the anode 11a are substantially uniform.
The four exhaust pipe lines 20 respectively penetrate through the four holes opened at equal intervals so as to surround the stage 11 or the anode 11a around the shaft 11x on the bottom surface of the chamber 10. A space between the hole and the outer periphery of the exhaust pipe 20 is sealed with a sealing material.

  The voltage setting unit 21 is a control device that sets a voltage or a current value between the anode 11a and the cathode 13, and includes a variable power source 21b. The voltage setting unit 21 is connected to the anode 11a and the cathode 13 by lead wires. Each lead wire passes through a hole provided in the chamber 10, and is connected to the cathode 13 and the anode 11a, respectively. The hole of the chamber 10 through which the lead wire is passed is sealed with a sealing material.

  The voltage setting unit 21 includes a control unit 21a. The control unit 21a is connected to the radiation thermometer 18 through a lead wire, and is connected to the variable power source 21b through a lead wire. When activated, the controller 21a refers to the temperature of the substrate 1 measured by the radiation thermometer 18, and the voltage or current between the anode 11a and the cathode 13 so that the temperature of the substrate 1 becomes a predetermined value. Adjust the value.

Next, a film forming process for forming a film on the substrate 1 using the DC plasma CVD apparatus of FIG. 1 will be described.
In this film formation process, an electron emission film made of carbon nanowalls is formed on the surface of the substrate 1.
The carbon nanowall is formed by connecting a plurality of petal-like (fan-like) carbon flakes that form a curved surface and are connected to each other in a random direction. Each carbon flake is composed of several to several tens of graphene sheets with a lattice spacing of 0.34 nm.
In the film forming process, first, for example, a nickel plate is cut out as the substrate 1, and degreasing and ultrasonic cleaning are sufficiently performed with ethanol or acetone. Next, when the surface of the substrate 1 is formed of metal, the surface of the substrate 1 is covered very thinly with a large number of insulating fine particles having a high melting point and a small diameter, such as diamond fine particles and aluminum oxide fine particles. This is because when the surface of the substrate 1 is made of metal, active species of the source gas diffuse into the substrate 1, and deposits due to the active species are difficult to deposit on the surface of the substrate 1. However, by covering the surface of the substrate 1 with a large number of insulating fine particles, deposits can be deposited from the surface of the insulating fine particles without substantially blocking the electric field between the anode 11a and the cathode 13.
The substrate 1 is placed on the anode 11a.

  When the placement of the substrate 1 is completed, the inside of the chamber 10 is then depressurized using an exhaust system, and subsequently, a compound containing carbon in the composition of hydrogen gas, methane and the like from the gas tube 19 as a source gas Of reaction gas (carbon-containing compound). The source gas is ejected from the ejection port 22 a of the ring nozzle 22.

  The reaction gas containing carbon in the composition of the raw material gas is desirably in the range of 3 vol% to 30 vol% of the whole. For example, the flow rate of methane is 50 SCCM, the flow rate of hydrogen is 500 SCCM, and the total pressure is 0.05 to 1.5 atm, preferably 0.07 to 0.1 atm. Further, the anode 11a is rotated together with the substrate 1 at 1 rpm with the axis 11x as an axis, a DC power supply is applied between the anode 11a and the cathode 13 so that the temperature variation on the substrate 1 is within 5%, and plasma is generated. The plasma state and the temperature of the substrate 1 are controlled.

  At the time of film formation of the carbon nanowall, film formation is performed for a predetermined time at a temperature of 900 ° C. to 1100 ° C. where the carbon nanowall of the substrate 1 is formed. This temperature is measured by a radiation thermometer 18. At this time, the cooling member 12 is sufficiently separated from the anode 11a so as not to affect the temperature of the anode 11a. The radiation thermometer 18 is set to obtain the temperature only from the heat radiation on the surface on the substrate 1 side by subtracting the plasma radiation of the DC plasma CVD apparatus.

In the process of forming the carbon nanowall, for example, when the film quality of the electron emission film is changed and a diamond layer containing a large number of diamond fine particles is laminated on the carbon nanowall, the cooling member 12 is raised to the anode 11a. Make contact. Thereby, the temperature of the board | substrate 1 can be cooled dramatically and a diamond layer can be laminated | stacked. Accompanying the growth of the diamond layer, sp ² -bonded carbon having a rod-like shape in which a part of the carbon nanowall is deformed and having a core clogged therein is grown from the gap between the diamond layers. This rod-like carbon extends so as to protrude from the surface of the diamond layer, and is easy to concentrate on the electric field due to the structure, and becomes a site for emitting electrons.

  At the end of film formation, the application of voltage between the anode 11a and the cathode 13 is stopped, and then the supply of the source gas is stopped, and nitrogen gas is supplied into the chamber 10 as a purge gas and the inside of the chamber 10 is supplied. After making the nitrogen atmosphere, the substrate 1 is taken out in a state of returning to room temperature.

The direct-current plasma CVD apparatus according to this embodiment has the following advantages (1) to (6).
(1) The ring nozzle 22 is disposed in the chamber 10, and the source gas is ejected horizontally from the ejection port 22 a of the ring nozzle 22 toward the shaft 11 x, that is, inwardly in the lateral direction. Exhaust from. Since the jet ports 22a are arranged at equal intervals in the ring nozzle 22 and the exhaust pipe lines 20 are arranged at equal intervals around the stage 11, the flow of the source gas is evenly symmetric about the axis 11x in the chamber 10. It has become. Further, since the cathode 13 and the cathode support 14 do not obstruct the flow of the source gas, the cathode 13 and the cathode support 14 efficiently flow up to just below the center of the cathode 13 having the axis 11x, and the source gas is even from the end on the substrate 1 to the center. , The density of active species generated from the source gas in the positive column PC becomes uniform, and the film can be formed evenly on the surface of the substrate 1.

Here, the result of investigating the influence of the difference in the flow method of the raw material gas will be described.
FIG. 3A and FIG. 3B are diagrams for explaining the configuration of a DC plasma CVD apparatus used for a comparative experiment. FIG. 3A is a view showing the gas shower nozzle 25, and FIG. 3B is a view showing the configuration of the DC plasma CVD apparatus.
FIG. 4A is a diagram showing a state of glow generated at the cathode in the DC plasma CVD apparatus shown in FIG. 3B, and FIG. 4B is a DC plasma CVD apparatus according to the first embodiment. In FIG. 1, it is a figure which shows the state of the glow which generate | occur | produces in a cathode.

  In this experiment, a part of the DC plasma CVD apparatus of FIG. 1 is arranged so that the flow of the source gas is not symmetric with respect to the axis 11x, and the cathode 13 is sterically hindered between the anode 11a and the nozzle. It has changed so that. For example, as shown in FIG. 3B, the ring nozzle 22 and the nozzle support 23 are removed from the chamber 10, and the gas tube 19 is connected to a gas shower nozzle 25 disposed above the cathode support 14 of the chamber 10. The gas is jetted downward from the gas shower nozzle 25 in the form of a shower, leaving only one of the plurality of exhaust pipes 20 and plugging other exhaust pipes 20 with, for example, plugs 24. Exhaust from the exhaust line 20 with the plug 24 is prevented. Other configurations are the same as those of the DC plasma CVD apparatus of FIG. In addition, in order to show the effect of the position of the inlet and outlet of the source gas with respect to the movement of the source gas that is a fluid, the DC plasma CVD apparatus of the comparative experiment also has the insulator 15 in the same manner as the DC plasma CVD apparatus of this embodiment. Provided.

  With the DC plasma CVD apparatus changed as shown in FIG. 3B and the DC plasma CVD apparatus shown in FIG. The source gas is hydrogen, the gas flow rate is 500 sccm, the gas pressure is 30 torr, and the current flowing through the cathode 13 is 2A.

  In the DC plasma CVD apparatus modified as shown in FIG. 3B, the source gas ejected from the gas shower nozzle 25 is drawn toward one exhaust pipe 20 where the plug 24 is not provided. As indicated by the arrows in FIG. 3 (a), the gas does not flow radially, and further, the gas does not flow symmetrically with respect to the axis 11x below the cathode 13, as shown by the two-dot chain line in FIG. 3 (b). The flow of the source gas concentrates toward the exhaust pipe 20 without the plug 24. Moreover, since the cathode 13 becomes a steric hindrance to the flow of the source gas, it is difficult to reach the axis 11x at the center of the anode 11a by going around the cathode 13, and the surface of the substrate 1 has an active species density reached. In-plane variation occurs. Such variation becomes more prominent as the cathode 13 and the anode 11a become larger as the substrate 1 becomes larger.

  Therefore, in the DC plasma CVD apparatus of FIG. 3B, the shape of the cathode glow generated at the cathode 13 is inclined as shown in FIG. 4A. If the shape of the cathode glow generated at the cathode 13 is tilted, this indicates that the temperature distribution is also tilted, so that there is a risk that film formation on the substrate 1 will vary. On the other hand, in the DC plasma CVD apparatus shown in FIG. 1, the glow generated in the cathode 13 is not inclined as shown in FIG. Therefore, uniform film formation on the substrate 1 is possible.

  (2) Since the gas tube 19 is composed of an insulator, the ring nozzle 22 is supported by an insulating nozzle support 23, and the ring nozzle 22 is insulated from the power source and the ground, it is unnecessary from the cathode 13 or the anode 11a. There is no occurrence of arc discharge.

  (3) Since the inner diameter of the ring-shaped ring nozzle 22 is larger than the outer diameter of the cathode 13 and the anode 11a, the ring nozzle 22 overlaps the positive column PC having a high density of active species between the cathode 13 and the anode 11a. Therefore, the temperature rise in the portion of the jet nozzle 22a of the ring nozzle 22 due to plasma is small, and the generation of deposits at the jet nozzle 22a is suppressed.

  (4) Since the height of the jet port 22a of the ring nozzle 22 is higher than the highest point of the positive column PC, the gas temperature of the positive column PC is partially changed from the side by the low temperature gas jetted from the jet port 22a. And the symmetry of the shape of the positive column PC is not disturbed.

  (5) The insulator 15 prevents the occurrence of arc discharge that hinders uniform film formation from the cathode 13 toward the outer periphery of the anode 11a.

  (6) Since the ring nozzle 22 is arranged at the same or lower position as the electrode surface of the cathode 13 and the source gas discharged from the ring nozzle 22 in the lateral direction is drawn to the lower exhaust pipe line 20, Highly reactive active species generated in the positive column PC can be prevented from coming into contact with the cathode 13 by diffusion. Therefore, it is possible to prevent deposition due to active species on the cathode 13 which causes arc discharge and spark.

[Second Embodiment]
FIGS. 5A and 5B are configuration diagrams of a DC plasma CVD apparatus according to the second embodiment of the present invention. Elements common to those in FIG. Yes.

  In this DC plasma CVD apparatus, the cathode 13 of the DC plasma CVD apparatus of FIG. 1 is changed to a cathode 27 and the voltage setting unit 21 is changed to a voltage setting unit 28.

  The cathode 27 includes a central electrode 27a facing the central portion of the anode 11a, a disk-shaped central electrode 27a facing the central portion of the anode 11a, and a ring shape surrounding the outer periphery of the central electrode 27a (FIG. 5B). And a peripheral electrode 27b concentric with the central electrode 27a and facing the peripheral part of the anode 11a, and an insulating part such as ceramic filled between the central electrode 27a and the peripheral electrode 27b without a gap. 27c.

  When the insulating portion 27c is not interposed between the central electrode 27a and the peripheral electrode 27b, the side wall of the central electrode 27a facing each other as well as the substrate 1 must be provided unless the distance between the central electrode 27a and the peripheral electrode 27b is sufficiently long. The electric field strength at the side wall of the peripheral electrode 27b becomes weak, and a portion not covered with the cathode glow is generated. Since there is little ion bombardment in this portion, deposits are easily deposited. Such deposits cause arc discharge and spark discharge. For this reason, by interposing the insulating portion 27c, the film is prevented from being deposited on the sidewalls of the central electrode 27a and the peripheral electrode 27b facing each other.

The voltage setting unit 28 includes a control unit 28a and variable power supplies 28b and 28c.
The control unit 28a is connected to the radiation thermometer 18 by a lead wire. The control unit 28a controls the variable power supplies 28b and 28c, and has a function of individually setting the voltage or current between the anode 11a and the central electrode 27a and the voltage or current between the anode 11a and the peripheral electrode 27b. have. Other configurations are the same as those of the DC plasma CVD apparatus of FIG.

  In the case of forming a film on the substrate 1 using the DC plasma CVD apparatus of FIG. 5, the substrate 1 is rotated at 1 rpm when the plasma is started up, and the voltage controller 28 controls between the anode 11a and the central electrode 27a. Is set larger than the potential difference between the anode 11a and the peripheral electrode 27b, and the voltage between the cathode 27 and the anode 11a is set. By applying such a voltage, a small positive column PC is generated between the anode 11a and the central electrode 27a. Thus, it is possible to prevent the occurrence of arc discharge that frequently occurs when a large positive column is generated from the beginning.

  After the stable positive column PC is formed on the upper portion of the central portion of the substrate 1 by applying voltage or current in this way, the control unit 28a has a voltage or current value between the anode 11a and the central electrode 27a. A voltage or current is applied so as to be less than the voltage between the anode 11a and the peripheral electrode 27b or less than the current value, thereby the temperature between the anode 11a and the central electrode 27a, the anode 11a and the peripheral electrode 27b. The substrate 1 is subjected to film formation by approximating or substantially matching the temperature between the two.

  As described above, in the present embodiment, the cathode 27 is constituted by the central electrode 27a and the peripheral electrode 27b, and the voltage or current value between the anode 11a and the central electrode 27a, and between the anode 11a and the peripheral electrode 27b. The voltage or current can be set independently. When the plasma is started up, the voltage between the anode 11a and the central electrode 27a is set higher than the voltage between the anode 11a and the peripheral electrode 27b. Thus, the positive column PC can be formed by shortening the distance between the anode 11a and the cathode 27. The voltage applied to the anode 11a and the cathode 27 may be low, and the occurrence frequency of arc discharge and spark discharge can be suppressed.

  In addition, the current flowing to the peripheral electrode 27b is reduced with respect to the current flowing to the central electrode 27a to generate the positive column PC concentrated at the center of the substrate 1, and then the power applied to the peripheral electrode 27b is increased. Thus, by increasing the current flowing through the peripheral electrode 27b, local arc discharge that occurs at the initial stage of film formation can be prevented, and then the positive column PC can be grown to a required size.

[Third Embodiment]
FIG. 6 is a configuration diagram of a DC plasma CVD apparatus according to the third embodiment of the present invention. Elements common to those in FIG. 1 are denoted by common reference numerals.

The DC plasma CVD apparatus includes a chamber 30 that is a reaction tank. The chamber 30 blocks the substrate 1 from the outside air.
A cylindrical steel stage 11 is disposed in the chamber 30, and an anode 11 a made of, for example, molybdenum or graphite having a good disk-like heat conductivity and a high melting point is placed on the stage 11. . The substrate 1 is rectangular and is fixed to the upper mounting surface of the anode 11a. The stage 11 is set to rotate about the axis 11x together with the anode 11a.

  The stage 11 below the anode 11a is provided with a closed space 11b, and a cooling member 12 is disposed in the space 11b. The cooling member 12 is provided to cool the substrate 1 as necessary, and has a structure in which the cooling member 12 is movable up and down as indicated by an arrow by a moving mechanism (not shown). The cooling member 12 is formed of a metal having high thermal conductivity such as copper, and inside thereof, a cooling medium such as cooled water or a cooled aqueous solution of calcium chloride passes from the pipe 12a to the flow path 12b in the cooling member 12. It circulates so as to be discharged from the pipe 12c, and cools the entire cooling member 12.

  For this reason, when the cooling member 12 moves upward, the upper surface 1 of the cooling member 12 contacts the lower surface of the stage 11, and the contacted stage 11 cools the upper anode 11 a, and the anode 11 a becomes the substrate 1. The structure that takes away the heat of. The cooling medium discharged from the pipe 12c is cooled by a cooling device (not shown) and circulated so as to be sent out again to the pipe 12a.

  A disc-shaped cathode 13 is disposed above the anode 11a. The cathode 13 is supported by the cathode support 14, and the cathode 13 and the anode 11a face each other. The cathode 13 is made of molybdenum or graphite having a high melting point. The cathode support 14 is made of a heat-resistant oxide such as quartz glass or alumina, a heat-resistant nitride such as aluminum nitride or silicon nitride, or a heat-resistant carbide such as silicon carbide.

  A flow path through which a cooling medium flows may be formed inside the cathode 13. When the cooling medium flows, overheating of the cathode 13 can be suppressed.

  An insulator 15 for suppressing arc generation is disposed in the vicinity of the outer peripheral surface of the anode 11a. The insulator 15 is made of at least one of a heat-resistant oxide such as quartz glass and alumina, a heat-resistant nitride such as aluminum nitride and silicon nitride, and a heat-resistant carbide such as silicon carbide.

The insulator 15 has a ring shape, and is supported at the same height as the anode 11a by a support 16 standing on the bottom of the chamber 30, and surrounds the outer periphery of the anode 11a on the inner peripheral side thereof. The outer diameter of the insulator 15 is at least 1.2 times the outermost diameter of the cathode 13.
The insulator 15 suppresses the occurrence of abnormal discharge (arc discharge, spark discharge) between the cathode 13 and the anode 11a, and is placed on the surface facing the cathode 13 along the outer peripheral side surface of the anode 11a. Then, the side surface of the anode 11 a may be hidden from the cathode 13.

  A window 17 is formed on the side surface of the chamber 30 so that the inside of the chamber 30 can be observed. The window 17 is fitted with heat-resistant glass to ensure airtightness in the chamber 30. A radiation thermometer 18 that measures the temperature of the substrate 1 through, for example, the glass of the window 17 is disposed outside the chamber 30.

  In this DC plasma CVD apparatus, a reactive gas system (not shown) for introducing a reactive gas as a raw material of active species through a gas tube 31 and a raw material system for introducing a matrix gas (carrier gas) through a gas tube 32 are used. (Not shown), an exhaust system (not shown) for adjusting the atmospheric pressure in the chamber 30 by discharging gas from the chamber 30 through the plurality of exhaust pipes 20, and a voltage setting unit 21.

  The gas tube 31 is made of an insulator and passes through a hole provided in the chamber 30. The space between the hole and the outer periphery of the gas tube 31 is sealed with a sealing material, and the airtightness in the chamber 30 is ensured. Inside the chamber 30, the gas tube 31 is connected to a ring nozzle 33.

  The ring nozzle 33 is the same as the ring nozzle 22 shown in FIG. 2, and on the ring-shaped inner peripheral surface side of the ring nozzle 33, a plurality of jet nozzles 33 a having the same diameter are arranged at equal intervals. The distance between the jet port 22a and the axis 11x, which is the central axis of the anode 11a, is also equal. The individual outlets 33a are provided point-symmetrically so that the outlets 33a face each other at opposite positions with the axis 11x as the center, and the source gas is uniformly jetted from the outlets 33a toward the axis 11x.

  The ring nozzle 33 is supported by an insulating nozzle support 23 attached to the cathode support 14. The height at which the ring nozzle 33 is supported is equal to or lower than the lowermost part of the cathode support 14 (the uppermost part of the side surface of the cathode 13 exposed from the cathode support 14), and the anode 11a and the cathode 13 are supported. Is set to be higher than the highest point of the positive column PC formed between the two. When the ring nozzle 33 is supported in this range, the reaction gas easily enters between the cathode 13 and the anode 11a, and the sunlight generated by locally cooling the gas temperature in the positive column PC by jetting the reaction gas. The disturbance of symmetry of the column PC can be suppressed.

  The inner diameter of the ring nozzle 33 is larger than the outer diameter of the cathode 13 and the outer diameter of the anode 11a. The center of the ring nozzle 33 is on the axis 11x of the anode 11a. The angles sandwiching each ejection port 33a from the center of the anode 11a are substantially uniform.

  The four exhaust ducts 20 respectively penetrate through the bottom surface of the chamber 30 through four holes that are opened at equal intervals so as to surround the stage 11 around the axis 11x. A space between the hole and the outer periphery of the exhaust pipe 20 is sealed with a sealing material.

  The voltage setting unit 21 is a control device that sets a voltage or a current value between the anode 11a and the cathode 13, and includes a variable power source 21b. The voltage setting unit 21 is connected to the anode 11a and the cathode 13 by lead wires. Each lead wire passes through a hole provided in the chamber 30 and is connected to the cathode 13 and the anode 11a, respectively. The hole of the chamber 30 through which the lead wire is passed is sealed with a sealing material.

  The voltage setting unit 21 includes a control unit 21a. The control unit 21a is connected to the radiation thermometer 18 through a lead wire, and is connected to the variable power source 21b through a lead wire. When activated, the controller 21a refers to the temperature of the substrate 1 measured by the radiation thermometer 18, and the voltage or current between the anode 11a and the cathode 13 so that the temperature of the substrate 1 becomes a predetermined value. Adjust the value.

The gas tube 32 is made of an insulator and passes through a hole provided in the chamber 30. The space between the hole and the outer periphery of the gas tube 32 is sealed with a sealing material, and the airtightness in the chamber 30 is ensured. Inside the chamber 30, the gas tube 32 is connected to a gas shower nozzle 34.
The gas shower nozzle 34 is arranged above the cathode support 14 that supports the cathode 13 and above the ring nozzle 33, and a plurality of jet nozzles having the same diameter are formed concentrically or radially around the axis 11x. Has been. Further, the individual outlets are provided point-symmetrically so that the outlets face each other at opposite positions around the axis 11x, and the matrix gas is jetted downward in a shower shape.

  The basic operation when forming a film using the DC plasma CVD apparatus of the present embodiment is the same as that when the DC plasma CVD apparatus of the first embodiment is used. However, in the case of the direct current plasma CVD apparatus of this embodiment, the matrix gas and the reactive gas are independently introduced, the reactive gas is ejected from the ring nozzle 33 in the inner lateral direction, and the matrix gas is ejected from the gas shower nozzle 34 downward. Is done. The matrix gas changes the flow vector of the reaction gas ejected in the lateral direction so as to flow toward the substrate 1 obliquely downward toward the substrate 1.

Here, a verification experiment on the height of the ring nozzle 33 will be described.
FIG. 7 is a diagram showing an outline of the verification experiment.
In this verification experiment, the diameter of the anode 11a and the cathode 13 is 160 mm, the thickness of each is 15 mm, the distance between the anode 11a and the cathode 13 is 60 mm, the inner diameter of the ring nozzle 33 is 305 mm, and the tube diameter is 0.25. The distance between the lower surface of the gas shower nozzle 34 and the lower surface of the cathode 13 is 260 mm, hydrogen of the matrix gas discharged from the gas shower nozzle 34 is 600 sccm, and argon of the matrix gas is 48 sccm. The reaction gas methane discharged from the 33 outlets 33a is 60 sccm, the gas pressure is 60 Torr, the current between the cathode 13 and the anode 11a is 16 A, and the substrate 1 is a square having a side of 75 mm and a thickness of 0.7 mm. Using a silicon substrate, the film formation time is 2 hours, and the ring nozzle 33 By changing the is, film formation was carried out. As shown in FIG. 7, when the position of the jet nozzle 33a of the ring nozzle 33 is 10 mm below the lower surface of the cathode 13, the position is high, and when the nozzle 33a is 10 mm above the upper surface of the anode 11a. Let it be low.

8 and 9 are diagrams for explaining the results of the verification experiment. In this verification experiment, the distance L1 between the observation point A, which is the center of the substrate 1 shown in FIG. 8 and located on the axis 11x, and an end face of the substrate 1 is 10 mm, and two adjacent to the end face. The growth of the carbon nanowall was observed at an observation point B where the distance L2 from the end face was 37.5 mm.
In addition, growth of carbon nanowalls was observed on the substrate 1 both when the reaction gas was released from the position high and when the reaction gas was released from the position low.
The upper left view and the upper right view of FIG. 9 show an observation point A and an observation point B, respectively, when plasma CVD is performed for 2 hours when the position of the jet outlet 33a of the ring nozzle 33 that jets the reaction gas is at the position high. 2 is a tomographic SEM image showing the growth of carbon nanowalls in FIG. The lower left diagram and the lower right diagram in FIG. 9 show an observation point A and an observation point B when the plasma CVD is performed for 2 hours when the position of the ejection port 33a of the ring nozzle 33 that ejects the reactive gas is at the position low. 2 is a tomographic SEM image showing the growth of carbon nanowalls in FIG.
As shown in the upper left diagram and the upper right diagram in FIG. 9, when the reactive gas was released only from the position high, there was not much difference in the growth degree of the carbon nanowall between the observation point A and the observation point B. On the other hand, as shown in the lower left diagram and the lower right diagram in FIG. 9, when the reactive gas is released only from the position low, a difference is observed, and the observation point B is more carbon than the observation point A. Nanowalls were growing greatly. This is because, in the case of the position low, the reaction gas ejected from the ring nozzle 33 is too low to reach the observation point A as compared with the case of the position high, and in the plasma outside the center portion. This is considered to be caused by the fact that the temperature difference between the central part and the peripheral part in the plasma becomes large in order to cool the temperature of the peripheral part. The decrease in the gas temperature in the plasma near the outer periphery of the substrate 1 leads to an increase in the density of active species having a relatively low chemical potential, resulting in uneven film formation.

  On the other hand, in the case of the position high, since the reaction gas is dispersed at a wide angle with respect to the positive column PC, it is relatively easy to reach the observation point A, and the low temperature reaction gas is locally only at the periphery of the positive column PC. Therefore, the temperature gradient in the gas is small and film formation unevenness does not occur.

Next, an experiment for observing the film formation state by changing the diameter of the ejection port 33a will be described.
The position of the ring nozzle 33 is set to the position high shown in FIG. 7, and the diameter of the ejection port 33a is changed to 0.5 mm, 1.0 mm, and 1.5 mm to change the emissivity on the surface of the substrate. Was measured. In the case where a graphite structure aggregate such as carbon nanowall is formed on a silicon substrate, the emissivity generally tends to increase as the film thickness increases. The gas moving speed immediately after ejection when the diameter of the ejection port 33a is 0.5 mm is 500 cm / s, and the gas moving speed immediately after ejection when the diameter of the ejection port 33a is 1.0 mm is 125 cm / s. When the diameter of the ejection port 33a is 1.5 mm, the gas moving speed immediately after ejection is 55 cm / s, and the flow rates of the reaction gas per unit time are made equal.

10 (a), 10 (b), and 10 (c) show plasma CVD apparatuses in which the diameter of the outlet 33a of the ring nozzle 33 at the position high is 0.5 mm, 1.0 mm, and 1.5 mm, respectively. 9 is an SEM cross-sectional image showing a film formation state at observation point A (substrate center) shown in FIG. 8 when performing plasma CVD treatment for 2 hours. FIG. 11 is a diagram showing the emissivity on the substrate 1 when the diameter of the ejection port 33a is 0.5 mm, 1.0 mm, and 1.5 mm.
When confirmed by a tomographic SEM observation, there is no significant difference in the growth of the carbon nanowalls in the vertical direction of the substrate at the observation points A and B when the diameter of the ejection port 33a is 0.5 mm, and the ejection port 33a. No significant difference is observed in the vertical growth of the carbon nanowalls at the observation points A and B when the diameter of the nozzle 33a is 1.0 mm, and the observation points A and B when the diameter of the ejection port 33a is 1.5 mm. There was no significant difference in the growth of carbon nanowalls in each of B in the vertical direction of the substrate. However, as shown in FIG. 10 (a), FIG. 10 (b), and FIG. 10 (c), when the nozzle diameter is 0.5 mm (φ0.5), and 1.0 mm (φ1.0) When the tomographic SEM images at the observation point A are compared in FIG. 10 in the case of 1.5 mm (φ1.5), the growth of the carbon nanowall in the substrate vertical direction in the case of φ1.0 and φ1.5 is It can be seen that it is larger than the case of φ0.5.

  As is clear from FIG. 11, the change in the emissivity of the substrate is almost unchanged at φ0.5 and φ1.0, reaching a plateau after 1 hour and 30 minutes, but φ1.5 is the radiation accompanying the growth of carbon nanowalls. There was a tendency for the rate increase to be delayed. Such an increase in emissivity depends on the density of the graphite component constituting the carbon nanowall on the substrate surface.

  Further, it is known that the growth of carbon nanowalls grows faster in the vertical direction of the substrate as the amount of active species that comes perpendicular to the substrate 1 increases. At φ0.5, the emissivity reaches a plateau quickly, and the height of the carbon nanowall is lower than that at φ1.0 and φ1.5, so the ratio of the lateral growth rate is φ1.0, φ1.5. It is thought that it is larger than the case. This is because the flow of active species produced by the plasma at φ0.5 has a larger lateral velocity component than the other two cases, the methane gas ejection speed is too high, and passes through the positive column PC of the plasma. This suggests that the gas flow is slightly disturbed.

In the case of φ1.5, the height of the carbon nanowall in the substrate vertical direction when the film formation time is 2 hours is the vertical direction of the carbon nanowall of φ0.5 and φ1.0 when the film formation time is 2 hours. Although the speed until the emissivity reaches a plateau is slower than in the other two cases, and the growth of the carbon nanowall in the substrate vertical direction is almost equal to φ1.0, Although the growth rate component in the direction is about the same as φ1.0, the deposition rate of the entire graphite component is slower than φ0.5 and φ1.0, and the lateral growth rate of the carbon nanowall becomes slower accordingly. Suggests that This is considered to be because the reaction gas ejection speed is slow, so that the convection of the reaction gas is less disturbed, but the amount of the reaction gas reaching the center of the plasma is less than that of φ0.5 and φ1.0. It is done.
That is, at the observation point A, the carbon nanowall formed with φ0.5 has a higher density of carbon nanowalls per unit area of the substrate than the carbon nanowall formed with φ1.5. Slow growth in direction. On the other hand, carbon nanowalls formed with a diameter of φ1.5 grow faster in the vertical direction of the substrate than carbon nanowalls formed with a diameter of φ0.5, but the density of carbon nanowalls per unit area of the substrate is sufficient. Slow until it gets higher. However, carbon nanowalls formed with a diameter of φ1.5 grow to a sufficient density after 2 hours of film formation.

  For this reason, in the case of the present embodiment, it is desirable that the moving speed of the reaction gas immediately after being ejected from the ring nozzle 33 is about 125 cm / s (φ1.0 nozzle) for uniform growth of carbon nanowalls. Although slightly inferior in uniformity, if good electron emission characteristics are obtained, the reaction gas moving speed is about 55 cm / s (φ1.5 nozzle) to about 125 cm / s (φ1.0 nozzle). It is desirable.

The direct-current plasma CVD apparatus of the present embodiment described above has the same effects as those of the first embodiment, and further has the advantage shown in the following (7).
(7) In general, it is known that the concentration of the reaction gas with respect to the matrix gas affects the film quality in CVD, but it is generated spontaneously by simply introducing a mixed gas in which the reaction gas and the matrix gas are mixed at a predetermined concentration. In the method of transporting the mixed gas to the substrate by convection, a part of the newly introduced mixed gas is exhausted from the exhaust port 20 before sufficiently reaching the substrate 1 depending on the convection. May be thinner than the concentration in the introduced mixed gas. Further, if the concentration of the reaction gas in the mixed gas is increased to compensate for this, deposition due to the reaction gas tends to occur on the cathode 13 and the cathode support 14 that supports the cathode 13, and this shifts the plasma to arc discharge or spark discharge. Cause. On the other hand, the direct current plasma CVD apparatus of this embodiment introduces the matrix gas and the reactive gas independently, makes the ejection position of the reactive gas relatively high with respect to the substrate 1, and further raises the matrix gas to a higher position. Since the ejection position is provided, the flow of the reaction gas can be operated toward the substrate 1 by the downforce of the matrix gas, and the amount of the reaction gas discharged unnecessarily can be reduced. Further, since the matrix gas ejection position is above the cathode 13 and the cathode support 14 that supports the matrix gas, and the reactive gas ejection position is below the lower surface of the cathode 13, the matrix gas reaches the exhaust pipe 20. Therefore, the reaction gas is prevented from flowing back toward the cathode 13 against the direction of the flow of the matrix gas, and the components of the reaction gas are applied to the cathode 13 and the cathode support 14 that supports the reaction gas. Can be prevented.

[Fourth Embodiment]
FIGS. 12A and 12B are configuration diagrams of a DC plasma CVD apparatus according to the fourth embodiment of the present invention, and are common to the DC plasma CVD apparatus according to the third embodiment in FIG. Common elements are denoted by common reference numerals.
In this DC plasma CVD apparatus, the cathode 13 of the DC plasma CVD apparatus of FIG. 6 is changed to a cathode 35 and the voltage setting unit 21 is changed to a voltage setting unit 36.

  The cathode 35 has a central electrode 35a facing the central portion of the anode 11a, and a ring shape (FIG. 12B) surrounding the outer periphery of the central electrode 35a. The cathode 35 is concentric with the central electrode 35a. A peripheral electrode 35b facing the peripheral part, and an insulating part 35c made of ceramic or the like filled without a gap between the central electrode 35a and the peripheral electrode 35b are provided.

  When the insulating portion 35c is not interposed between the central electrode 35a and the peripheral electrode 35b, the distance between the central electrode 35a and the peripheral electrode 35b is not long enough. A film grown by active species is deposited on the side wall of the electrode 35b. For this reason, by interposing the insulating portion 35c, the film is prevented from being deposited on the sidewalls of the central electrode 35a and the peripheral electrode 35b facing each other.

The voltage setting unit 36 includes a control unit 36a and variable power supplies 36b and 36c.
The control unit 36a is connected to the radiation thermometer 18 by a lead wire. The control unit 36a has a function of controlling the variable power sources 36b and 36c and individually setting the voltage or current between the anode 11a and the central electrode 35a and the voltage or current between the anode 11a and the peripheral electrode 35b. have. Other configurations are the same as those of the DC plasma CVD apparatus of FIG.

  When the DC plasma CVD apparatus of FIG. 12 is used to form a film on the substrate 1, the substrate 1 is rotated at 1 rpm when the plasma is started, and is controlled between the anode 11 a and the central electrode 35 a by the control of the voltage control unit 36. Is set higher than the voltage between the anode 11a and the peripheral electrode 35b, and the voltage between the cathode 35 and the anode 11a is set. By applying such a voltage, it is possible to generate a positive column PC of plasma between the anode 11a and the central electrode 35a, and to prevent arc generation at the initial stage of film formation.

  As described above, after the stable positive column PC is formed on the upper portion of the central portion of the substrate 1 by the application of voltage or current, the control unit 19a has a voltage or current value between the anode 11a and the central electrode 35a. A voltage or current is applied so as to be less than the voltage between the anode 11a and the peripheral electrode 35b or less than the current value, whereby the temperature between the anode 11a and the central electrode 35a, and the anode 11a and the peripheral electrode 35b. The substrate 1 is subjected to film formation by approximating or substantially matching the temperature between the two.

  As described above, in the present embodiment, the cathode 35 is constituted by the central electrode 35a and the peripheral electrode 35b, and the voltage or current value between the anode 11a and the central electrode 35a, and between the anode 11a and the peripheral electrode 35b. The voltage or current can be set independently. When the plasma is started up, the voltage between the anode 11a and the central electrode 35a is set higher than the voltage between the anode 11a and the peripheral electrode 35b. Thereby, the positive column PC can be formed by shortening the distance between the anode 11a and the cathode 35. The voltage applied to the anode 11a and the cathode 35 may be low, and the occurrence frequency of arc discharge and spark discharge can be suppressed.

  In addition, the current flowing to the peripheral electrode 35b is reduced with respect to the current flowing to the central electrode 35a to generate the positive column PC concentrated at the center of the substrate 1, and then the power applied to the peripheral electrode 35b is increased. By increasing the current flowing through the peripheral electrode 35b, local arc discharge occurring at the initial stage of film formation can be prevented, and then the positive column PC can be grown to a required size.

[Fifth Embodiment]
FIG. 13 is a configuration diagram showing a DC plasma CVD apparatus according to the fifth embodiment of the present invention.
14 is a schematic view showing the cathode, source gas nozzle, and exhaust pipe line of the DC plasma CVD apparatus of FIG. 13 from above.
FIG. 15 is a schematic cross-sectional view of the DC plasma CVD apparatus of FIG. 13 as viewed from the side.

This DC plasma CVD apparatus is an apparatus for forming a film on the surface of a substrate 1 to be processed, and includes a chamber 50 that is a reaction tank. The chamber 50 blocks the substrate 1 from the outside air.
In the chamber 50, a rectangular parallelepiped steel stage 51 is disposed, and an anode 51a made of, for example, molybdenum or graphite having a high heat conductivity and a high melting point is placed on the stage 51. Yes. The substrate 1 is fixed to the upper placement surface of the anode 51a. The substrate 1 may be rectangular or a plurality of square substrates 1 may be arranged on the anode 51a.

  A closed space 51b is provided in the stage 51 below the anode 51a, and a cooling member 52 is disposed in the space 51b. The cooling member 52 is provided to cool the substrate 1 as necessary, and has a structure in which the cooling member 52 is movable up and down as indicated by an arrow by a moving mechanism (not shown). The cooling member 52 is formed of a metal having high thermal conductivity such as copper, and inside thereof, a cooling medium such as cooled water or a cooled aqueous solution of calcium chloride passes from the pipe line 52a to the flow path 52b in the cooling member 52. The refrigerant is circulated so as to be discharged from the pipe 52c, and the entire cooling member 52 is cooled.

  For this reason, when the cooling member 52 moves upward, the upper surface of the cooling member 52 comes into contact with the lower surface of the stage 51, the contacted stage 51 cools the anode 51 a on the upper side, and the anode 51 a becomes the substrate 1. It has a structure that takes heat away. The upper surface of the cooling member 52 has a rectangular shape, and cools the entire length direction of the stage 51.

The cooling medium discharged from the pipe 52c is cooled by a cooling device (not shown) and circulated so as to be sent out again to the pipe 52a.
In addition, a space 51b provided below the anode 51a is partitioned by the stage 51, and is filled with gas or opened to the atmosphere.

A rectangular plate-like cathode 53 is disposed above the anode 51a. The cathode 53 is supported by a cathode support 54, and the cathode 53 and the anode 51a face each other. The cathode 53 is made of molybdenum or graphite having a high melting point.
The cathode support 54 is made of a heat-resistant oxide such as quartz glass or alumina, a heat-resistant nitride such as aluminum nitride or silicon nitride, or a heat-resistant carbide such as silicon carbide.

  Inside the cathode 53, a flow path through which a cooling medium flows may be formed. When the cooling medium flows, overheating of the cathode 53 can be suppressed. As the cooling medium, water introduced from the outside of the chamber 50, an aqueous calcium chloride solution, or the like is preferable.

  An insulator 15 for suppressing arc generation is disposed in the vicinity of the outer peripheral surface of the anode 11a. The insulator 15 is made of at least one of a heat-resistant oxide such as quartz glass and alumina, a heat-resistant nitride such as aluminum nitride and silicon nitride, and a heat-resistant carbide such as silicon carbide.

The insulator 55 has an annular shape and is supported at the same height as the anode 51a by a support 56 standing on the bottom of the chamber 50, and surrounds the outer periphery of the anode 51a close to the inner periphery thereof.
The insulator 55 suppresses the occurrence of abnormal discharge (arc discharge, spark discharge) between the cathode 53 and the anode 51a, and is placed facing the cathode 53 along the outer peripheral side surface of the anode 51a. ing. The insulator 55 may hide the side surface of the anode 51 a from the cathode 53.

  A window 57 is formed on the side surface of the chamber 50 so that the inside of the chamber 50 can be observed. The window 57 is fitted with heat-resistant glass to ensure airtightness in the chamber 50. A radiation thermometer 58 that measures the temperature of the substrate 1 through, for example, the glass of the window 57 is disposed outside the chamber 50.

  In this DC plasma CVD apparatus, a source system (not shown) for introducing a source gas containing a reaction gas through a gas tube 59 and a gas are discharged from the chamber 50 through a plurality of exhaust pipes 60. 50 is provided with an exhaust system (not shown) for adjusting the atmospheric pressure in 50 and a voltage setting unit 61.

  The gas tube 59 is inserted into the chamber 10 through a hole provided in the chamber 50, and at least a part of the gas tube 59 in the reaction tank is made of an insulator such as fluororesin or silicon rubber. Yes. The space between the hole and the outer periphery of the gas tube 59 is sealed with a sealing material, and the airtightness in the chamber 50 is ensured. In the chamber 50, the gas tube 59 is connected to a nozzle 62 which is a gas introduction nozzle.

  The nozzle 62 has a portion 62A parallel to one long side of the anode 51a and the cathode 53 and a portion 62B parallel to one other long side of the anode 51a and the cathode 53. The entire nozzle 62 may have an annular shape, or the portions 62 </ b> A and 62 </ b> B may be branched from a connection point with the gas tube 59. The nozzle 62 is hollow so that the source gas flows. In the portions 62A and 62B of the nozzle 62, a plurality of jet ports 62a are formed at equal intervals in line symmetry with respect to the axis 53x that is the central axis along the longitudinal direction of the cathode 53 with the portions 62A and 62B. The source gas is ejected horizontally from the ejection port 62a toward the substrate 1, that is, inwardly in the lateral direction.

  The nozzle 62 is supported by an insulating nozzle support 63 attached to the cathode support 54. The height at which the nozzle 62 is supported is a position where the jet port 62a is below the lowermost portion of the cathode support 54 (the uppermost portion of the side surface exposed from the cathode support 54 of the cathode 53), and the anode 51a and the cathode 53 is set so as to be higher than the highest point of the positive column PC formed between the two. If the nozzle 62 is supported in this range, the source gas can easily enter between the cathode 53 and the anode 51a, and the temperature of the positive column PC can be prevented from being locally cooled by the ejection of the source gas. .

The interval between the portions 62A and 62B of the nozzle 62 is larger than the width (short direction) of the cathode 53, and the portions 62A and 62B of the nozzle 62 are further disposed on both sides of the cathode 53 in the long direction as shown in FIG. Located outside. The portions 62A and 62B are substantially equidistant from the longitudinal center line of the anode 11a.
The exhaust duct 60 passes through a plurality of holes opened at equal intervals so as to surround the stage 11 on the bottom surface of the chamber 50. A space between the hole and the outer periphery of the exhaust pipe 60 is sealed with a sealing material.

  The voltage setting unit 61 is a control device that sets the voltage or current value between the anode 51a and the cathode 53, and includes a control unit 61a and a variable power source 61b. The voltage setting unit 61, the anode 51a, and the cathode 53 are connected by lead wires. Each lead wire passes through a hole provided in the chamber 50. The hole of the chamber 50 through which the lead wire is passed is sealed with a sealing material.

  The control unit 61a of the voltage setting unit 61 is connected to the radiation thermometer 58 via a lead wire, and is connected to the variable power source 61b via a lead wire. When activated, the control unit 61a refers to the temperature of the substrate 1 measured by the radiation thermometer 58, and the voltage or current between the anode 51a and the cathode 53 so that the temperature of the substrate 1 becomes a predetermined value. Adjust the value.

Next, a film forming process for forming a film on the substrate 1 using the DC plasma CVD apparatus of FIG. 13 will be described.
In this film formation process, an electron emission film made of carbon nanowalls is formed on the surface of the substrate 1.
In the film forming process, first, for example, a nickel plate is cut out as the substrate 1, and degreasing and ultrasonic cleaning are sufficiently performed with ethanol or acetone.
The substrate 1 is placed on the anode 51a.

  When the placement of the substrate 1 is completed, the inside of the chamber 50 is then depressurized using an exhaust system, and subsequently, carbon gas is contained in the composition of hydrogen gas, methane, and the like from the gas tube 59 as a source gas. The reaction gas (carbon-containing compound) of the compound is led. The source gas is ejected from the ejection port 62 a of the nozzle 62.

  At the time of film formation of the carbon nanowall, film formation is performed for a predetermined time at a temperature of 900 ° C. to 1100 ° C. where the carbon nanowall of the substrate 1 is formed. This temperature is measured by a radiation thermometer 58. At this time, the cooling member 52 is sufficiently separated from the anode 51a so as not to affect the temperature of the anode 51a. The radiation thermometer 58 is set so as to obtain the temperature only from the heat radiation on the surface on the substrate 1 side by subtracting the plasma radiation of the DC plasma CVD apparatus.

In the process of forming the carbon nanowall, for example, when the film quality of the electron emission film is changed and a diamond layer containing a large number of diamond fine particles is laminated on the carbon nanowall, the cooling member 52 is raised to the anode 51a. Make contact. Thereby, the temperature of the board | substrate 1 can be cooled dramatically and a diamond layer can be laminated | stacked. Accompanying the growth of the diamond layer, sp ² bond carbon in which a part of the car carbon nanowall is deformed in a rod shape and the core is clogged is grown from the gap between the diamond layers. This rod-like carbon extends so as to protrude from the surface of the diamond layer, and is easy to concentrate on the electric field due to the structure, and becomes a site for emitting electrons.

  At the end of the film formation, the application of voltage between the anode 51a and the cathode 53 is stopped, and then the supply of the source gas is stopped, and nitrogen gas is supplied into the chamber 50 as a purge gas and the inside of the chamber 50 is supplied. After making the nitrogen atmosphere, the substrate 1 is taken out in a state of returning to room temperature.

In the DC plasma CVD apparatus according to the present embodiment as described above, the same effects as (1) to (6) of the first embodiment can be obtained, and further, the advantages shown in the following (8) and (9) are obtained. Have.
(8) If film formation is to be performed on the substrate 1 having a large area, it is necessary to increase the areas (outer diameters) of the anode 11a and the cathode 13 in the DC plasma CVD apparatus of the first embodiment. However, when the outer diameters of the anode 11a and the cathode 13 are increased, the reaction gas supplied to the center of the anode 11a may be insufficient, or a temperature difference that cannot be ignored between the outer peripheral side and the center portion may occur. For this reason, there is a risk of variations in film formation.

  On the other hand, in the DC plasma CVD apparatus according to the above-described embodiment, the anode 51a and the cathode 53 are rectangular, and the portions 62A and 62B of the nozzle 62 are arranged to move in the longitudinal direction. As a result, it is possible to supply a source gas that does not vary in the longitudinal direction, and suppress variations in film formation in the longitudinal direction. Therefore, if the lengths of the anode 51a and the cathode 53 in the short direction are appropriately set, film formation with reduced variation can be performed on the substrate 1 having a large area.

  (9) Since the anode 51a and the cathode 53 are rectangular, the square substrate 1 can be arranged side by side in the longitudinal direction of the anode 51a and the cathode 53, and film formation is simultaneously performed on a plurality of substrates 1 at a time. Suitable for mass production. In this case, since a plurality of substrates 1 are formed in the same lot, it is not necessary to consider the variation between lots if the required number of films are formed simultaneously.

[Sixth Embodiment]
FIG. 16A is a configuration diagram of a DC plasma CVD apparatus according to the sixth embodiment of the present invention, and FIG. 16B is a plan view of the cathode viewed from below.
FIG. 17 is a diagram showing the cathode, source gas nozzle, and exhaust pipe line of the DC plasma CVD apparatus of FIG.
FIG. 18 is a cross-sectional view of the DC plasma CVD apparatus of FIG.

  In this DC plasma CVD apparatus, the cathode 53 of the DC plasma CVD apparatus of the fifth embodiment shown in FIG. 13 is changed to a cathode 65, and the voltage setting unit 61 is changed to a voltage setting unit 66.

The cathode 65 has a central electrode 65a facing the central portion of the anode 51a, an annular shape (FIG. 16B) surrounding the outer periphery of the central electrode 65a, a peripheral electrode 65b facing the peripheral portion of the anode 51a, and a central electrode And an insulating portion 65c made of ceramic or the like filled with no gap between the peripheral electrode 65b and the peripheral electrode 65b.
When the insulating portion 65c is not interposed between the central electrode 65a and the peripheral electrode 65b, the side wall and the periphery of the opposing central electrode 65a as well as the substrate 1 are necessary unless the distance between the central electrode 65a and the peripheral electrode 65b is sufficiently long. A film grown by active species is deposited on the side wall of the electrode 65b. For this reason, by interposing the insulating portion 65c, it is possible to prevent the carbon film from being deposited on the side wall of the central electrode 65a and the side wall of the peripheral electrode 65b facing each other.

The voltage setting unit 66 includes a control unit 66a and variable power supplies 66b and 66c.
The controller 66a is connected to the radiation thermometer 58 with a lead wire. The controller 66a controls the variable power supplies 66b and 66c, and has a function of individually setting a voltage or current between the anode 51a and the central electrode 65a and a voltage or current between the anode 51a and the peripheral electrode 65b. have. The other structure is the same as that of the DC plasma CVD apparatus of FIG.

  When the DC plasma CVD apparatus of FIG. 16 is used to form a film on the substrate 1, the potential difference between the anode 51 a and the central electrode 65 a is controlled by the voltage controller 66 when the plasma is started up. The voltage between the cathode 65 and the anode 51a is set so as to be larger than the potential difference between the electrode 65b. By applying such a voltage, it is possible to generate a positive column PC of plasma between the anode 51a and the central electrode 65a, and to prevent generation of an arc at the initial stage of film formation.

  By applying voltage or current in this way, a stable positive column PC is formed on the upper part of the central portion of the substrate 1. Thereafter, the controller 66a applies the voltage or current so that the voltage or current value between the anode 51a and the central electrode 65a is less than the voltage or current value between the anode 51a and the peripheral electrode 65b. As a result, the temperature between the anode 51a and the central electrode 65a and the temperature between the anode 51a and the peripheral electrode 65b are approximated or substantially matched to form a film on the substrate 1.

  As described above, in the present embodiment, the cathode 65 is composed of the central electrode 65a and the peripheral electrode 65b, and the voltage or current value between the anode 51a and the central electrode 65a and between the anode 51a and the peripheral electrode 65b. The voltage or current can be set independently. When the plasma is started up, the voltage between the anode 51a and the central electrode 65a is set higher than the voltage between the anode 51a and the peripheral electrode 65b. Thereby, the positive column PC can be formed by shortening the distance between the anode 51a and the cathode 65. The voltage applied to the anode 51a and the cathode 65 may be low, and the occurrence frequency of arc discharge and spark discharge can be suppressed.

  In addition, the positive column PC concentrated at the long center of the substrate 1 is generated by reducing the current flowing to the peripheral electrode 65b with respect to the current flowing to the central electrode 65a, and then applied to the peripheral electrode 65b. By increasing the power to increase the current flowing through the peripheral electrode 65b, local arc discharge that occurs at the initial stage of film formation can be prevented, and then the positive column PC can be grown to a required size.

[Seventh Embodiment]
FIG. 19 is a configuration diagram of a DC plasma CVD apparatus according to the seventh embodiment of the present invention. Elements common to those in FIG. 13 are denoted by common reference numerals.
FIG. 20 is a diagram showing the cathode, the reaction gas nozzle, the matrix gas nozzle, and the exhaust pipe line of the DC plasma CVD apparatus of FIG. 19 from above.
FIG. 21 is a cross-sectional view of the DC plasma CVD apparatus of FIG. 19 viewed from the side.

This DC plasma CVD apparatus is an apparatus for forming a film on the surface of a substrate 1 to be processed, and includes a chamber 70 that is a reaction tank. The chamber 70 blocks the substrate 1 from the outside air.
A rectangular parallelepiped steel stage 51 is disposed in the chamber 70, and an anode 51 a made of, for example, molybdenum or graphite having a high thermal conductivity and a high melting point is placed on the stage 51. . The substrate 1 is fixed to the upper placement surface of the anode 51a. The substrate 1 may be rectangular or a plurality of square substrates 1 may be arranged on the anode 51a.

  A closed space 51b is provided in the stage 51 below the anode 51a, and a cooling member 52 is disposed in the space 51b. The cooling member 52 is provided to cool the substrate 1 as necessary, and has a structure in which the cooling member 52 is movable up and down as indicated by an arrow by a moving mechanism (not shown). The cooling member 52 is formed of a metal having high thermal conductivity such as copper, and inside thereof, a cooling medium such as cooled water or a cooled aqueous solution of calcium chloride passes from the pipe line 52a to the flow path 52b in the cooling member 52. The refrigerant is circulated so as to be discharged from the pipe 52c, and the entire cooling member 52 is cooled.

  For this reason, when the cooling member 52 moves upward, the upper surface of the cooling member 52 comes into contact with the lower surface of the stage 51, the contacted stage 51 cools the anode 51 a on the upper side, and the anode 51 a becomes the substrate 1. It has a structure that takes heat away. The upper surface of the cooling member 52 has a rectangular shape, and cools the entire length direction of the stage 51.

The cooling medium discharged from the pipe 52c is cooled by a cooling device (not shown) and circulated so as to be sent out again to the pipe 52a.
In addition, a space 51b provided below the anode 51a is partitioned by the stage 51, and is filled with gas or opened to the atmosphere.

A rectangular plate-like cathode 53 is disposed above the anode 51a. The cathode 53 is supported by a cathode support 54, and the cathode 53 and the anode 51a face each other. The cathode 53 is made of molybdenum or graphite having a high melting point.
The cathode support 54 is made of a heat-resistant oxide such as quartz glass or alumina, a heat-resistant nitride such as aluminum nitride or silicon nitride, or a heat-resistant carbide such as silicon carbide.

  Inside the cathode 53, a flow path through which a cooling medium flows may be formed. When the cooling medium flows, overheating of the cathode 53 can be suppressed. As the cooling medium, water introduced from the outside of the chamber 70, an aqueous calcium chloride solution, or the like is preferable.

  In the vicinity of the outer peripheral surface of the anode 51a, an insulator 55 for suppressing the generation of an arc is disposed. The insulator 55 is made of at least one of a heat-resistant oxide such as quartz glass and alumina, a heat-resistant nitride such as aluminum nitride and silicon nitride, and a heat-resistant carbide such as silicon carbide.

The insulator 55 has an annular shape, and is supported at the same height as the anode 51a by a support 56 standing at the bottom of the chamber 70, and surrounds the outer periphery of the anode 51a close to the inner periphery thereof.
The insulator 55 suppresses the occurrence of abnormal discharge (arc discharge, spark discharge) between the cathode 53 and the anode 51a, and is placed facing the cathode 53 along the outer peripheral side surface of the anode 51a. ing. The insulator 55 may hide the side surface of the anode 51 a from the cathode 53.

  A window 57 is formed on the side surface of the chamber 70 so that the inside of the chamber 70 can be observed. The window 57 is fitted with heat-resistant glass to ensure airtightness in the chamber 70. A radiation thermometer 58 that measures the temperature of the substrate 1 through, for example, the glass of the window 57 is disposed outside the chamber 70.

  In this direct current plasma CVD apparatus, a reaction gas system (not shown) for introducing a reaction gas through a gas tube 71, a raw material system (not shown) for introducing a matrix gas through a gas tube 72, and a gas from the chamber 70 are used. Are exhausted through a plurality of exhaust pipes 60 to adjust the atmospheric pressure in the chamber 70, and a voltage setting unit 61 is provided.

  The gas tube 71 is inserted into the chamber 70 through a hole provided in the chamber 70, and at least part of the reaction tank is made of an insulator such as fluororesin or silicon rubber. The space between the hole and the outer periphery of the gas tube 71 is sealed with a sealing material, and the airtightness in the chamber 70 is ensured. In the chamber 70, the gas tube 71 is connected to a nozzle 73 which is a reactive gas introduction nozzle.

  The nozzle 73 has a portion 73A parallel to one long side of the anode 51a and the cathode 53, and a portion 73B parallel to one other long side of the anode 51a and the cathode 53. The entire nozzle 73 may be annular, or the portions 73 </ b> A and 73 </ b> B may be branched from a connection point with the gas tube 71. The nozzle 73 is hollow so that the reaction gas flows. In the portions 73A and 73B of the nozzle 73, a plurality of jet ports 73a are formed at equal intervals in line symmetry with the portions 73A and 73B, and the source gas is horizontally directed from the jet port 73a toward the substrate 1, that is, It is ejected inward and laterally.

  The nozzle 73 is supported by an insulating nozzle support 63 attached to the cathode support 54. The height at which the nozzle 73 is supported is a position where the jet port 73 a is below the lowermost portion of the cathode support 54 (the uppermost portion on the exposed side surface of the cathode 53), and between the anode 51 a and the cathode 53. It is set to be higher than the highest point of the possible positive column PC. When the nozzle 73 is supported in this range, the source gas can easily enter between the cathode 53 and the anode 51a, and the temperature of the positive column PC can be prevented from being locally cooled by the ejection of the source gas. .

The interval between the portions 73A and 73B of the nozzle 73 is larger than the width (short direction) of the cathode 53, and the portions 62A and 62B of the nozzle 62 are further disposed on both sides of the cathode 53 in the long direction as shown in FIG. Located outside. The portions 73A and 73B are substantially equidistant from the longitudinal center line of the anode 51a.
The exhaust duct 60 passes through a plurality of holes opened at equal intervals so as to surround the stage 71 on the bottom surface of the chamber 70. A space between the hole and the outer periphery of the exhaust pipe 60 is sealed with a sealing material.

  The voltage setting unit 61 is a control device that sets the voltage or current value between the anode 51a and the cathode 53, and includes a control unit 61a and a variable power source 61b. The voltage setting unit 61, the anode 51a, and the cathode 53 are connected by lead wires. Each lead wire passes through a hole provided in the chamber 70. The hole of the chamber 60 through which the lead wire is passed is sealed with a sealing material.

  The control unit 61a of the voltage setting unit 61 is connected to the radiation thermometer 58 via a lead wire, and is connected to the variable power source 61b via a lead wire. When activated, the control unit 61a refers to the temperature of the substrate 1 measured by the radiation thermometer 58, and the voltage or current between the anode 51a and the cathode 53 so that the temperature of the substrate 1 becomes a predetermined value. Adjust the value.

The gas tube 72 is made of an insulator and passes through a hole provided in the chamber 70. The space between the hole and the outer periphery of the gas tube 72 is sealed with a sealing material, and the airtightness in the chamber 70 is ensured. In the chamber 70, the gas tube 72 is connected to a gas shower nozzle 74 for matrix gas.
The gas shower nozzle 74 has substantially the same length as the cathode 53, is located above the cathode support 54 that supports the cathode 53 and above the nozzle 73, and extends along the longitudinal direction of the cathode 53. It is arranged so as to be parallel and line symmetric with respect to the axis 53x which is the central axis, and the matrix gas is jetted downward in a shower shape.

The basic operation when forming a film using the DC plasma CVD apparatus of the present embodiment is the same as that when the DC plasma CVD apparatus of the fifth embodiment is used. However, in the case of the DC plasma CVD apparatus of this embodiment, the matrix gas and the reactive gas are independently introduced, the reactive gas is ejected from the nozzle 73 in the inner lateral direction, and the matrix gas is ejected from the gas shower nozzle 74 downward. The The matrix gas changes the flow vector of the reaction gas ejected in the lateral direction so as to flow toward the substrate 1 obliquely downward toward the substrate 1.
The direct current plasma CVD apparatus of the present embodiment as described above can obtain the same effects as those of the fifth embodiment, and further has the advantage shown in the following (10).

  (10) In general, it is known that the concentration of the reaction gas with respect to the matrix gas affects the film quality in CVD, but it is generated spontaneously by simply introducing a mixed gas in which the reaction gas and the matrix gas are mixed at a predetermined concentration. In the method of transporting the mixed gas to the substrate by convection, a mixed gas that can be sufficiently formed on the substrate 1 by the newly introduced mixed gas is discharged from the exhaust port 60 before reaching the substrate 1 sufficiently. , There is a possibility of wasteful consumption of reaction gas. Further, if the concentration of the reaction gas in the mixed gas is increased to compensate for this, deposition due to the reaction gas tends to occur on the cathode 53 and the insulating cathode support 54 that supports the cathode 53. It becomes the cause which shifts to discharge. On the other hand, the direct current plasma CVD apparatus of this embodiment introduces the matrix gas and the reactive gas independently, makes the ejection position of the reactive gas relatively high with respect to the substrate 1, and further raises the matrix gas to a higher position. Since the ejection position is provided, the flow of the reaction gas can be controlled toward the substrate 1 by the down force of the matrix gas, the ejection position of the matrix gas is located above the cathode 53 and the insulating cathode support 54 that supports the cathode 53, and Since the ejection position of the reactive gas is set below the lower surface of the cathode 53, down force is applied until the matrix gas reaches the exhaust pipe 60, so that the reactive gas opposes the flow direction of the matrix gas. Therefore, it is possible to prevent the reaction gas components from adhering to the cathode 53 and the insulating structure 54 that supports the cathode 53.

[Eighth Embodiment]
22 (a) and 22 (b) are configuration diagrams of a DC plasma CVD apparatus according to the eighth embodiment of the present invention. Elements common to those in FIG. Yes.
FIG. 23 is a diagram showing the cathode, the reactive gas nozzle, the matrix gas nozzle, and the exhaust pipe line of the DC plasma CVD apparatus of FIG.
FIG. 24 is a cross-sectional view of the DC plasma CVD apparatus of FIG.

  In this DC plasma CVD apparatus, the cathode 53 of the DC plasma CVD apparatus according to the seventh embodiment shown in FIG. 19 is changed to a cathode 75 and the voltage setting unit 61 is changed to a voltage setting unit 76.

  The cathode 75 has a central electrode 75a facing the central portion of the anode 51a, an annular shape (FIG. 22B) surrounding the outer periphery of the central electrode 75a, a peripheral electrode 75b facing the peripheral portion of the anode 51a, and a central electrode And an insulating portion 75c made of ceramic or the like filled with no gap between 75a and the peripheral electrode 75b.

  When the insulating portion 75c is not interposed between the central electrode 75a and the peripheral electrode 75b, the distance between the central electrode 75a and the peripheral electrode 75b is not long enough. A film grown by active species is deposited on the side wall of the electrode 75b. For this reason, by interposing the insulating part 75c, it is possible to prevent the carbon film from being deposited on the sidewalls of the central electrode 75a and the peripheral electrode 75b facing each other.

The voltage setting unit 76 includes a control unit 66a and variable power sources 76b and 76c.
The controller 76a is connected to the radiation thermometer 58 with a lead wire. The control unit 76a has a function of controlling the variable power sources 76b and 76c and individually setting the voltage or current between the anode 51a and the central electrode 75a and the voltage or current between the anode 51a and the peripheral electrode 75b. have. Other configurations are the same as those of the DC plasma CVD apparatus of FIG.

  When a film is formed on the substrate 1 using the DC plasma CVD apparatus of FIG. 22, the voltage between the anode 51a and the central electrode 75a is controlled by the voltage control unit 76 at the time of starting the plasma. The voltage between the cathode 75 and the anode 51a is set so as to be higher than the voltage between the electrode 75b. By applying such a voltage, it is possible to generate a positive column PC of plasma between the anode 51a and the central electrode 75a, and to prevent generation of an arc at the initial stage of film formation.

  By applying voltage or current in this way, a stable positive column PC is formed on the upper part of the central portion of the substrate 1. Thereafter, the controller 76a applies the voltage or current so that the voltage or current value between the anode 51a and the central electrode 75a is less than the voltage or current value between the anode 51a and the peripheral electrode 75b. As a result, the temperature between the anode 51a and the central electrode 75a and the temperature between the anode 51a and the peripheral electrode 75b are approximated or substantially matched to form a film on the substrate 1.

  As described above, in the present embodiment, the cathode 75 includes the central electrode 75a and the peripheral electrode 75b, and the voltage or current value between the anode 51a and the central electrode 75a and between the anode 51a and the peripheral electrode 75b. The voltage or current can be set independently. When the plasma is started up, the voltage between the anode 51a and the central electrode 75a is set higher than the voltage between the anode 51a and the peripheral electrode 75b. Accordingly, the positive column PC can be formed by shortening the distance between the anode 51a and the cathode 75. The voltage applied to the anode 51a and the cathode 75 may be low, and the occurrence frequency of arc discharge and spark discharge can be suppressed.

  Further, the current flowing to the peripheral electrode 75b is reduced with respect to the current flowing to the central electrode 75a to generate the positive column PC concentrated at the long center of the substrate 1, and then applied to the peripheral electrode 75b. By increasing the power to increase the current flowing through the peripheral electrode 75b, local arc discharge that occurs at the initial stage of film formation can be prevented, and then the positive column PC can be grown to a required size.

In addition, this invention is not limited to the said embodiment, A various deformation | transformation is possible. Examples of such modifications include the following.
(A) The configuration of the cathodes 27 and 35 including a plurality of electrodes can be changed as appropriate depending on the size of the substrate 1 and the anode 11a to be processed. For example, the cathode 90 in FIG. 25 includes a central electrode 90a and a plurality of peripheral electrodes 27b. In this case, the voltage or current value between the plurality of peripheral electrodes 90b and the anode 11a may be set individually. An insulating portion 90c made of ceramic is filled between the center electrode 90a and the peripheral electrode 90b. In the cathodes 91 and 92 shown in FIGS. 26 and 27, a plurality of peripheral electrodes 91b and 92b are circular in the same size as the central electrodes 91a and 92a. In each of the cathodes 91 and 92, an insulating portion 14c made of ceramic is filled between the peripheral electrodes 91b and 92b and the central electrodes 91a and 92a.

  (B) The configuration of the cathodes 27 and 35 is such that the central electrodes 27a and 35a and the peripheral electrodes 27b and 35c are arranged concentrically. However, as in the cathode 93 shown in FIG. An electrode 93a, a ring-shaped first peripheral electrode 93b that surrounds and surrounds the outer periphery of the central electrode 93a, and a ring-shaped second peripheral electrode 93c that surrounds and surrounds the outer periphery of the first peripheral electrode 93b. Good.

(C) The cooling member 12 can also be modified.
FIG. 29A is a top view showing another modified example of the cooling member 12 of the DC plasma CVD apparatus, and FIG. 29B is a cooling member along the line AA in FIG. 12 is a schematic cross-sectional view of FIG. FIG. 30A is a top view of the cooling member 12 of FIG. 29, and FIG. 30B shows an operation at the time of cooling of the cooling member 12 along the line BB of FIG. 30A. FIG.
In the plasma CVD apparatus shown in FIGS. 29A and 29B, pipes 12a, 12b, and 12c through which the cooling medium supplied from the cooling apparatus 99 passes are formed in the cooling member 12. Further, a groove 12 </ b> C that communicates from the vent 12 </ b> B to the side surface 12 </ b> D of the cooling member 12 is formed on the upper surface 12 </ b> A of the cooling member 12. Therefore, as shown in FIG. 30B, even if the upper surface 12A of the cooling member 12 abuts on the stage 11, the cold air gas moves as indicated by the arrow through the flow path formed between the groove 12C and the stage. Therefore, it is possible to efficiently cool by venting. Further, the helium gas whose discharge flow rate is adjusted by the flow rate adjusting unit 95 is sent from the helium gas sealing unit 94 to the three-way valve 98. The nitrogen gas whose discharge flow rate is adjusted by the flow rate adjusting unit 97 is sent from the nitrogen gas sealing unit 96 to the three-way valve 98. When the three-way valve 98 is opened, the cooled helium gas and the cooled nitrogen gas are sprayed onto the contact surface of the stage 11 through the vent 12B, so that the substrate 1 can be cooled. Even if the cool air gas is not directly blown onto the contact surface of the stage 11, the same effect can be obtained only by filling the space 11 b partitioned by the stage 11 with the cool air gas.

1 is a configuration diagram illustrating a plasma CVD apparatus according to a first embodiment of the present invention. It is a top view which shows the ring nozzle and exhaust port in FIG. It is a figure explaining the structure of the DC plasma CVD apparatus utilized for the comparative experiment. It is a figure which shows the state of the glow which generate | occur | produces in a cathode. It is a block diagram of the direct-current plasma CVD apparatus which concerns on the 2nd Embodiment of this invention. It is a block diagram of the direct-current plasma CVD apparatus which concerns on the 3rd Embodiment of this invention. It is a figure which shows the outline | summary of a verification experiment. It is a figure explaining the result of verification experiment. It is a figure explaining the result of verification experiment. It is a figure which shows an experimental result. It is a figure which shows an experimental result. It is a block diagram which shows the DC plasma CVD apparatus which concerns on the 4th Embodiment of this invention. It is a block diagram which shows the direct-current plasma CVD apparatus which concerns on the 5th Embodiment of this invention. It is the figure which showed the cathode of the direct-current plasma CVD apparatus of FIG. It is sectional drawing which looked at the DC plasma CVD apparatus of FIG. 13 from the side. It is a block diagram of the DC plasma CVD apparatus which concerns on the 6th Embodiment of this invention. It is the figure which showed the cathode of the direct-current plasma CVD apparatus of Fig.16 (a), the source gas nozzle, and the exhaust pipe line from the upper direction. It is sectional drawing which looked at the direct-current plasma CVD apparatus of Fig.16 (a) from the side. It is a block diagram of the direct-current plasma CVD apparatus which concerns on the 7th Embodiment of this invention. It is the figure which showed the cathode, the reactive gas nozzle, the matrix gas nozzle, and the exhaust pipe line of the DC plasma CVD apparatus of FIG. 19 from the upper side. It is sectional drawing which looked at the DC plasma CVD apparatus of FIG. 19 from the side. It is a block diagram of the DC plasma CVD apparatus which concerns on the 8th Embodiment of this invention. It is the figure which showed the cathode of the DC plasma CVD apparatus of Fig.22 (a), the nozzle for reaction gas, the nozzle for matrix gas, and the exhaust pipe from the upper direction. It is sectional drawing which looked at the direct-current plasma CVD apparatus of Fig.22 (a) from the side. It is a figure which shows the modification of a cathode. It is a figure which shows the modification of a cathode. It is a figure which shows the modification of a cathode. It is a figure which shows the modification of a cathode. It is a figure which shows the modification of a cooling member. It is a figure which shows the modification of a cooling member. It is a figure for demonstrating the flow of the gas in the reaction tank of the conventional plasma CVD apparatus.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Substrate 10, 30, 50, 70 ... Chamber, 11, 51 ... Stage, 11a, 51a ... Anode, 12, 52 ... Cooling member, 13, 27, 53, 65 75, cathode, 14, 54 ... cathode support, 15, 55 ... insulator, 20, 60 ... exhaust pipe, 22, 33, 62 ... ring nozzle, 34,. 74 ... Gas shower nozzle

Claims (19)

A first electrode disposed in the reaction vessel and on which the substrate is placed;
A second electrode facing the first electrode above the first electrode and generating plasma between the first electrode;
A region where plasma is generated between the first electrode and the second electrode and disposed between the first electrode and the second electrode in the reaction vessel. A first gas introduction nozzle formed with a plurality of jets arranged to surround
A plasma CVD apparatus comprising:   2. The plasma CVD apparatus according to claim 1, wherein the first gas introduction nozzle introduces a gas containing a source gas in which active species are formed by the plasma.   3. The plasma CVD apparatus according to claim 1, wherein the first gas introduction nozzle introduces a gas including a raw material gas in which active species are formed by the plasma and a matrix gas. 4.   4. The gas discharge nozzle according to claim 1, wherein the first gas introduction nozzle jets a gas laterally from the plurality of jet nozzles toward a central axis of the first electrode. 5. Plasma CVD equipment.   5. The plasma CVD apparatus according to claim 1, wherein the first gas introduction nozzle is disposed so as to surround a periphery of the first electrode. 6.   The plasma CVD apparatus according to any one of claims 1 to 5, wherein the plurality of jet nozzles of the first gas introduction nozzle are arranged at equal intervals.   The plasma CVD apparatus according to any one of claims 1 to 6, wherein the plurality of jet nozzles of the first gas introduction nozzle have the same distance from the central axis of the first electrode. .   Each set of jets composed of two of the plurality of jets of the first gas introduction nozzle is disposed so as to face each other with the central axis of the first electrode as a center. The plasma CVD apparatus according to any one of claims 1 to 7.   The height of the jet outlet of the first gas introduction nozzle is at a position higher than the highest point of the region where the positive column of the plasma is generated. The plasma CVD apparatus as described.   The plasma CVD apparatus according to claim 1, wherein the first gas introduction nozzle has a ring shape.   The plasma according to any one of claims 1 to 10, wherein the first gas introduction nozzle is a tube facing each other along a side of the second electrode in the reaction vessel. CVD equipment.   12. The apparatus according to claim 1, further comprising a second gas introduction nozzle that ejects the matrix gas from above the second electrode toward the gas ejected from the first gas introduction nozzle. The plasma CVD apparatus according to the item.   The plasma CVD apparatus according to claim 1, further comprising: a plurality of discharge conduits that are disposed below the first electrode and discharge gas from the reaction vessel.   And a plurality of discharge conduits disposed under the first electrode and surrounding the periphery of the first electrode for discharging gas from the reaction vessel. 14. The plasma CVD apparatus according to any one of 1 to 13. The second electrode is composed of a plurality of electrodes,
15. The voltage or current between each electrode of the second electrode and the first electrode is individually set to an arbitrary value, respectively. Plasma CVD equipment. The plurality of electrodes includes a central electrode facing a central portion of the first electrode and a peripheral electrode facing a peripheral portion of the first electrode,
At the time of rising, the voltage or current value between the central electrode and the first electrode is set higher than the voltage or current value between the peripheral electrode and the first electrode.
The plasma CVD apparatus according to claim 15. The plurality of electrodes are composed of the central electrode facing the central portion of the first electrode and the peripheral electrode facing the peripheral portion of the first electrode,
After a positive column is formed between the central electrode and the first electrode, the voltage or current value between the central electrode and the first electrode is determined between the peripheral electrode and the first electrode. Be less than the voltage or current value between,
The plasma CVD apparatus according to claim 15 or 16, characterized in that   The plasma CVD apparatus according to claim 15, wherein an insulator is disposed between the plurality of electrodes.   A voltage is applied between the first electrode and the second electrode on which the substrate is placed, and the reactive gas is ejected from a plurality of ejection ports arranged so as to surround a region where plasma is generated. A film forming method.