JP2000178744A - Film forming equipment - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To supply a raw material gas into plasma without waste, and to maintain thermal energy of a plasma jet,
A plasma jet having a high active species concentration acts on the substrate to improve the film formation rate. A film forming apparatus (11) includes a substrate support in a film forming chamber (1).
(2) is disposed, and a plasma generating section is disposed opposite to the substrate support (2). In the plasma generating section, arc discharge is performed between the discharge anode (3) and the discharge anode (4) to convert the carrier gas supplied from the carrier gas introduction hole (5a) into plasma, and the discharge anode (3) A plasma jet (P) is jetted from the opening (3b) formed in the substrate toward the substrate (S). A source gas introduction pipe (6) is provided below the opening (3b), and the source gas is supplied toward the plasma jet (P). Further, a closed space (7) having an outlet (7c) is provided immediately above the substrate support table (2) adjacent to the opening (3b), and the raw material gas escaping from the plasma jet is again discharged into the plasma jet (P). ).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a film forming apparatus for forming a functional thin film of amorphous silicon, polycrystalline silicon, diamond, DLC (diamond-like carbon), CBN or the like on the surface of a substrate by a plasma jet. More specifically, the present invention relates to a film forming apparatus capable of forming the thin film at high speed by arc discharge.

[0002]

2. Description of the Related Art As an apparatus for forming a functional thin film, for example,
Japanese Patent Publication No. 4-77710 discloses a vapor phase synthesis apparatus for diamond using a DC arc discharge thermal plasma jet. In the gas phase synthesis apparatus disclosed in the publication, a rod-shaped cathode is disposed around the axis of an anode having a bottomed cylindrical shape having a circular opening formed at the bottom, and a DC voltage is applied between the cathode and the anode. To discharge the arc. At this time,
A mixed gas of a carrier gas and a raw material gas is supplied between the anode and the cathode. Is formed with a thin film.

As described above, since the raw material gas is hard to be converted into plasma, the raw material gas is mixed with a carrier gas such as hydrogen and supplied between the anode and the cathode to promote the conversion of the raw material gas into plasma. However, since it is difficult to convert all of the supplied source gases into plasma, the source gas concentration in the plasma jet is low, and the deposition rate is also low.

For this reason, in another gas phase synthesis apparatus disclosed in the publication, only a carrier gas is supplied between the anode and the cathode to generate plasma, and the plasma is directed toward the plasma jet ejected from the opening of the anode. The source gas is blown from the source gas supply pipe. Thus, by supplying the raw material gas to the plasma jet, the raw material gas is converted into plasma with high efficiency.

However, since the plasma jet ejected from the opening has a high gas pressure and is ejected with a strong force, a part of the raw material gas blown from the periphery of the plasma jet is pushed back by the force of the plasma jet. I will be. Therefore, not all the source gases can be blown into the plasma jet, and some of the source gases are diffused into the processing chamber without being turned into plasma. As described above, even when the raw material gas is supplied to the plasma jet, not all of the raw material gas can be efficiently turned into plasma, and the film formation rate cannot be increased.

Therefore, in a diamond manufacturing apparatus disclosed in, for example, Japanese Patent Application Laid-Open No. 2-248397, a rod-shaped cathode is arranged at the center of the axis of a bottomed cylindrical anode having an opening at the center of the inclined bottom. An arc is discharged between the anode and the cathode to convert the carrier gas into plasma. Further, in the manufacturing apparatus disclosed in the publication, the anode is disposed at the center of the axis of a nozzle body having a bottomed cylindrical shape having an opening at the center of the inclined bottom similarly to the anode and having a diameter larger than that of the anode. are doing. A source gas supply passage is formed between the nozzle body and the anode. Therefore, the raw material gas blows out from the slit-shaped outlet of the opening of the anode and the opening of the nozzle body, and immediately after the plasma jet blows out from the opening of the anode, the raw material gas flows from the entire circumference toward the plasma jet. Supplied.

As described above, in the diamond manufacturing apparatus disclosed in the publication, the raw material gas is supplied from the slit-shaped outlet disposed immediately below the opening of the anode in a direction orthogonal to the entire circumference of the plasma jet. Because of the supply, the source gas can be blown into the plasma jet more efficiently than in the past.

[0008]

However, a part of the source gas is still repelled by the plasma jet, which has a high gas pressure and is strong, or slips through the opening of the nozzle body and diffuses into the film forming chamber. As a result, all the supplied source gas cannot be turned into plasma, and the source gas is wasted. Further, the thermal energy of the plasma jet blown out from the opening of the nozzle body to the wide space of the film forming chamber escapes to the outside of the plasma jet by radiation until it reaches the substrate. As a result, the activity of the entire plasma jet decreases, and the concentration of active species effective for film formation in the plasma jet when the plasma jet reaches the substrate decreases, so that the film formation speed also decreases.

The present invention has been made in order to solve such a conventional problem. All of the supplied source gases are turned into plasma, so that the source gases can be efficiently contributed to the film formation by eliminating waste of the source gases. It is an object of the present invention to maintain the thermal energy of a plasma jet, allow a plasma jet having a high concentration of active species to act on a substrate, and improve the film formation rate.

[0010]

In order to achieve the above object, the present invention provides a film forming chamber having a substrate support, and an opening directed to the substrate support in the film formation chamber. ,
A film forming apparatus comprising: a plasma generating unit that converts a carrier gas into plasma by arc discharge; and a raw material gas inlet that introduces a raw material gas into a plasma jet generated by the plasma generating unit. A film forming apparatus having an outlet at a position immediately above the outlet, and a closed space for mixing the plasma jet and the source gas formed between the outlet and the opening. And

According to the film forming apparatus, the carrier gas is turned into plasma by the arc discharge in the plasma generating section, and the converted carrier gas is ejected from the opening of the plasma generating section as a plasma jet.
A raw material gas is supplied into the plasma jet to convert the raw material gas into plasma, which is used as an active species that contributes to film formation on the substrate.

When the source gas is supplied to the plasma jet ejected from the opening, since the plasma jet has a high gas pressure and a strong jetting force, a part of the source gas supplied to the plasma jet is generated by the plasma jet. It will be pushed back without being taken into the jet. However, in the film forming apparatus of the present invention, an outlet is provided at a position immediately above the substrate support, and a closed space is formed between the outlet and the opening. The source gas stops in the closed space without diffusing into the film forming chamber, and is again supplied to the plasma jet. Therefore, almost all of the supplied source gas can be taken into the plasma jet, and the source gas can be converted into plasma without waste and contribute to film formation.

Further, the plasma jet ejected from the opening is surrounded by a sealed space up to a position immediately above the substrate support table, thereby suppressing thermal energy of the plasma jet from escaping to the outside of the plasma jet by radiation. Can be. Therefore, the activity of the plasma jet can be maintained at a high level until it reaches the substrate surface, and the active species effective for film formation can be maintained at a high concentration. In order to maintain the thermal energy of the plasma jet in a higher state, it is preferable that the closed space is formed using a material having high heat insulation.

It is preferable that a cross-sectional dimension of the outlet in the closed space is set smaller than a diameter of the plasma jet. By setting the size of the outlet smaller than the diameter of the plasma jet in this way, it is possible to effectively prevent the raw material gas once taken into the plasma jet from escaping to the outside of the plasma jet again. It is possible to keep the active species of the source gas at a high concentration in the plasma jet until the substrate reaches the substrate.

It is preferable that the closed space is partitioned in a direction crossing the plasma jet by at least one partition having a single plasma passage hole.
In this way, by dividing the closed space by the partition walls and forming a plurality of smaller closed regions, the source gas pushed back from the plasma jet can be supplied to the plasma jet again more efficiently.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The embodiments of the present invention will be specifically described below with reference to preferred embodiments. FIG. 1 is a longitudinal sectional view schematically showing a film forming apparatus 11 according to a first embodiment of the present invention. The film forming apparatus 11 has a film forming chamber 1, and the film forming chamber 1 is evacuated from an exhaust port 1a so as to be in a vacuum. Further, a substrate support 2 is provided on the floor 1 b of the film forming chamber 1, and a substrate S is mounted on the surface of the substrate support 2. Note that a temperature control mechanism for maintaining the substrate S at a predetermined temperature is provided inside the substrate support 2.

Further, the substrate support 2 is provided in the film forming chamber 1.
A discharge anode 3 and a discharge cathode 4, which are plasma generation units, are arranged on an upper wall 1c facing the fin. The discharge anode 3 is formed of a conductive bottomed cylinder having an opening 3b at the bottom 3a, and a rod-shaped discharge cathode 4 is disposed at the center of the axis. The upper portions of the discharge anode 3 and the discharge cathode 4 are closed by an insulating member 5 having a carrier gas introduction hole 5a.

The discharge anode 3 and the discharge cathode 4 are connected to a DC power supply DC. When a DC voltage is applied to the electrodes 3 and 4, an arc discharge occurs between the electrodes 3 and 4. The arc discharge causes the carrier gas introduction hole 5
The carrier gas introduced from a is turned into plasma, and a plasma jet P is ejected from an opening 3 b formed in the discharge anode 3.

Below the discharge anode 3 in the film forming chamber 1, a source gas introduction pipe 6 is arranged in a direction perpendicular to the direction of jetting of the plasma jet P. Introductory pipe 6
The raw material gas outlet 6a is opened toward a position directly below the opening 3b formed in the discharge anode 3, and
The raw material gas is supplied to the plasma jet P ejected from b in a direction perpendicular to the plasma jet P, and the raw material gas is turned into plasma. In the illustrated embodiment, the number of the source gas introducing pipes 6 is one, but a plurality of the source gas introducing pipes 6 may be arranged radially from the center of the plasma jet P. Further, the source gas introduction pipe 6 is connected to the plasma jet P in accordance with the gas pressure of the plasma jet P and the force of the jet.
The jetting direction of the plasma jet P may be changed in an appropriate manner, or the plasma jet P may be supplied in the circumferential direction without being orthogonal to the plasma jet P.

Further, according to the present invention, the opening 3b from which the plasma jet P is jetted and the substrate support 2
A closed space 7 having an outlet 7c at a position immediately above the substrate support 2 is formed between the plasma jet P and the source gas. The closed space 7
It is composed of a cylindrical peripheral wall 7a and a bottom wall 7b having an outlet 7c. The upper end of the peripheral wall 7a is directly attached to the discharge anode 3 while being fitted to the bottom 3a of the discharge anode 3. Therefore, the peripheral wall 7a and the bottom wall 7b of the closed space 7
Are electrically connected to the discharge anode 3 and have the same potential.

The cross section of the outlet 7c of the closed space 7 is set smaller than the diameter of the plasma jet P.
The peripheral wall 7a and the bottom wall 7b forming the closed space 7 are made of a material having a low thermal conductivity, a high heat insulating property and a high melting point, such as tungsten, tantalum, carbon, and molybdenum.

When a source gas is supplied from the source gas introducing pipe 6 to the plasma jet P blown out from the opening 3b formed in the discharge anode 3, a part of the source gas is taken into the plasma jet P, but a part thereof is taken into the plasma jet P. Is pushed back out of the plasma jet P by the gas pressure of the plasma jet P without being taken into the plasma jet P. The raw material gas thus escaped from the plasma jet P diffuses into the closed space 7, but as shown by arrows in FIG. 1, the raw material gas is dispersed by the peripheral wall 7a and the bottom wall 7b in the closed space. The light is reflected and collides again with the plasma jet P, and is taken into the plasma jet P. Therefore, almost all of the supplied source gas can be taken into the plasma jet P, and the source gas can be converted into plasma without waste and contribute to film formation.

Further, since the size of the outlet 7c of the closed space 7 is set smaller than the diameter of the plasma jet P, the raw material gas once taken into the plasma jet P is once again discharged to the outside of the plasma jet P. Without stopping, the plasma jet P can be stopped in the plasma jet P until it reaches the substrate.

As described above, since the film forming apparatus of the present invention has the closed space 7, it is possible to efficiently supply the source gas escaping to the outside of the plasma jet P to the plasma jet P again, In addition, since the source gas once taken into the plasma jet P can be stopped in the plasma jet P without escaping, the concentration of the source gas in the plasma jet P increases, and the film forming speed improves. .

Further, the plasma jet P blown out from the opening 3b is surrounded by a narrow space such as the closed space 7, and the peripheral wall 7 forming the closed space 7 is formed.
By using a material having a high heat insulating property for a and the bottom metal 7b, it is possible to suppress the thermal energy of the plasma jet P from escaping to the outside due to radiation. Therefore, the activity can be maintained in a high state until the plasma jet P reaches the substrate surface, and the concentration of active species effective for film formation can be maintained at a high concentration. Therefore, the film forming speed is further improved, and the conventional closed space 7 is improved.
The speed is more than twice as fast as that of a film forming apparatus having no.

Hereinafter, another embodiment of the present invention will be described. In the following embodiments, the same components as those of the film forming apparatus 11 according to the above-described first embodiment are denoted by the same reference numerals, and detailed description thereof will be omitted.

FIG. 2 is a longitudinal sectional view schematically showing a part of a film forming apparatus 12 according to a second embodiment of the present invention. In the film forming apparatus 12 according to the present embodiment, the peripheral wall 7 forming the closed space 7 'is used.
a ′ has a tapered shape whose diameter gradually decreases from the upper end to the lower end. In this way, by making the peripheral wall 7a 'tapered, the source gas that escaped from the plasma jet P is positively guided again toward the plasma jet P, and the source gas is smoothly taken into the plasma jet P. And the film formation speed is also improved.

FIG. 3 is a longitudinal sectional view schematically showing a part of a film forming apparatus 13 according to a third embodiment of the present invention. In the film forming apparatus 13 according to the present embodiment, a bottomed cylindrical body 8 having a circular opening 8a formed at the bottom is attached to the upper wall 1c of the film forming chamber 1. At the axial center of the bottomed cylinder 8, the discharge anode 3 is arranged with a slight gap 8b. The upper end of the bottomed cylindrical body 8 is tightly fitted and fixed to the upper outer wall surface of the discharge anode 3 in a state in which a raw material gas introduction hole 8c is partially formed. The source gas introduced from the source gas introduction hole 8c is supplied to the entire outer periphery of the plasma jet P ejected from the opening 3b formed in the discharge anode 3 through the gap 8b.

Further, a closed space 7 is provided at the lower end of the bottomed cylindrical body 8. The peripheral wall 7a constituting the closed space 7 is directly attached to the bottomed cylindrical body 8 in a state of being fitted to the bottom. Therefore, the peripheral wall 7a and the bottom wall 7b constituting the closed space 7 are also
The closed space 7, the bottomed cylindrical body 8, and the discharge anode 3 are all at the same potential.

In the film forming apparatus 13 of the third embodiment, a cylindrical body 8 having a bottom is disposed outside the discharge anode 3 and the discharge anode 3 is provided.
The raw material gas can be supplied from all around to the plasma jet P ejected from the opening 3b formed in
More source gas can be efficiently taken into the plasma jet P. However, even in this embodiment, a part of the supplied raw material gas is pushed back by the plasma jet P having a high gas pressure, and is not taken into the plasma jet P. Escapes to the closed space 7 from the opening 8a. The raw material gas that escaped to the closed space 7 is, as shown by an arrow in FIG.
The light is reflected by the peripheral wall 7a and the like constituting the closed space 7 and supplied to the plasma jet P again, and is taken into the plasma jet P.

FIG. 4 is a longitudinal sectional view schematically showing a part of a film forming apparatus 14 according to a fourth embodiment of the present invention. In the film forming apparatus 14 according to the present embodiment, a bottomed cylindrical body 8 is disposed outside the discharge anode 3 with a gap 8b, and a raw material gas is introduced from a raw material gas introduction hole 8c formed on the bottomed cylindrical body 8. Introduce gas. The raw material gas is supplied to the entire outer periphery of the plasma jet P ejected from the opening 3b of the discharge anode 3 through the gap 8b. Further, in the film forming apparatus 14, a raw material gas introduction pipe 6 is arranged below the bottomed cylindrical body 8 in a direction orthogonal to the direction of jetting the plasma jet P, and an opening 8a of the bottomed cylindrical body 8 is provided. The raw material gas is further supplied to the plasma jet P ejected from the nozzle.

As described above, by supplying the source gas in two stages, more source gas can be supplied to the plasma jet P, and the concentration of the active species contributing to film formation in the plasma jet P can be increased. Can be increased. Therefore, the film forming speed is also remarkably improved.

FIG. 5 is a longitudinal sectional view schematically showing a part of a film forming apparatus 15 according to a fifth embodiment of the present invention. Also in the film forming apparatus 15 according to the present embodiment, a closed space 7 ″ is disposed between the opening 3b of the discharge anode 3 and the substrate support 2. The closed space 7 ″ is the first embodiment described above. As in the example, a cylindrical peripheral wall 7a constituting the same space 7 ″ is attached at its upper end to the bottom 3a of the discharge anode 3, and the lower end of the peripheral wall 7a is closed by a bottom wall 7b having an outlet 7c. Have been.

Further, the closed space 7 "of the present embodiment is divided at the center thereof in the direction transverse to the plasma jet P by a partition 7d having a single plasma passage hole 7e at the center. A region is formed.
A source gas introduction pipe 6 is provided in each of the sealed areas toward the plasma jet P, and the source gas is introduced in each area.

As described above, the closed space 7 "is divided into smaller closed spaces by the partition walls 7d.
The raw material gas that has been pushed back without being taken in by the plasma jet P is immediately thereafter the partition wall 7d or the peripheral wall 7a.
Will be in contact with. For this reason, the source gas has a small decrease in momentum when blown from the introduction pipe 6 and is again supplied to the plasma jet P with a relatively strong momentum, and the amount of the source gas taken into the plasma jet P increases. I do.

In the present embodiment, since the source gas introduction pipes 6 are arranged in the upper and lower mixing regions, respectively, and the source gas is supplied in two stages, it is possible to further increase the concentration of the source gas in the plasma jet P. Although it is possible, the source gas introducing pipe 6 arranged in the lower mixing area can be eliminated.

FIG. 6 is a longitudinal sectional view schematically showing a part of a film forming apparatus 16 according to a sixth embodiment of the present invention. The film forming apparatus 16 has a closed space 7 in the film forming apparatus 12 according to the second embodiment in which a bottomed cylindrical body 8 is arranged outside the discharge anode 3 and a raw material gas is supplied from the entire outer periphery of the plasma jet P.
Is changed to the closed space 7 ″ partitioned by the partition 7d in the fifth embodiment described above. In the film forming apparatus 16, the upper and lower portions of the sealed space 7 ″ partitioned by the partition 7d are also provided. It is also possible to arrange the source gas introduction pipes 6 in the closed areas, respectively, and supply the source gas in three stages.

Further, the film forming apparatus 15 of the fifth embodiment and the sixth
In the film forming apparatus 16 of the embodiment, the closed space 7 ″ is partitioned into two upper and lower sealed areas by one partition wall 7d.
It is also possible to further partition in multiple steps by a plurality of partition walls 7d.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view schematically showing a film forming apparatus according to a first embodiment of the present invention.

FIG. 2 is a longitudinal sectional view schematically showing a film forming apparatus according to a second embodiment of the present invention.

FIG. 3 is a longitudinal sectional view schematically showing a film forming apparatus according to a third embodiment of the present invention.

FIG. 4 is a longitudinal sectional view schematically showing a film forming apparatus according to a fourth embodiment of the present invention.

FIG. 5 is a longitudinal sectional view schematically showing a film forming apparatus according to a fifth embodiment of the present invention.

FIG. 6 is a longitudinal sectional view schematically showing a film forming apparatus according to a sixth embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Film-forming chamber 1a Exhaust port 1b Floor 1c Upper wall 2 Substrate support 3 Discharge anode 3a Bottom 3b Opening 4 Discharge cathode 5 Insulating member 5a Carrier gas inlet 6 Source gas inlet 6a Source gas outlet 7,7 ', 7 "Enclosed space 7a, 7a' Peripheral wall 7b Bottom wall 7c Exit 7d Partition wall 7e Plasma passage hole 8 Bottomed cylindrical body 8a Opening 8b Gap 8c Source gas introduction hole 11-16 Film forming apparatus S substrate P Plasma jet DC DC power supply

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4K030 AA16 BA28 BA29 BA30 BA39 EA06 FA01 KA30 5F045 DP03 EB03 EH05 EH08 EH18 EH19

Claims (3)

[Claims] A film forming chamber having a substrate support, an opening facing the substrate support in the film formation chamber, and a plasma generating unit for converting a carrier gas into plasma by arc discharge;
A film forming apparatus comprising: a source gas inlet for introducing a source gas into a plasma jet generated by the plasma generating unit; and an outlet at a position immediately above the substrate support, wherein the outlet and the opening Wherein a closed space for mixing the plasma jet and the source gas is formed between them. 2. The film forming apparatus according to claim 1, wherein a cross-sectional dimension of the outlet in the closed space is set smaller than a diameter of the plasma jet. 3. The sealed space is defined by one or more partitions each having a single plasma passage hole in a direction transverse to the plasma jet.
A film forming apparatus as described in the above.