JP2002121668A - Thermal cvd apparatus for forming graphite nanofiber thin film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To constitute a thermal CVD apparatus for forming graphite nanofiber thin film so that a growth speed of the thin film is increased and a thin film having uniform film thickness distribution is formed regardless of a size and an external shape of a substrate to be treated. SOLUTION: An apparatus is provided with a mixed gas supply system 18 to introduce a mixed gas of a carbon containing gas and a hydrogen gas into a vacuum chamber. A mixed gas heating means 21 to heat the mixed gas introduced in the chamber to a prescribed temperature is arranged to the mixed gas supply system. Further, introduction of the mixed gas in the vacuum chamber is conducted through a gas injection nozzle means 19 which is arranged at a lower side than a height position of a substrate S to be treated and encircles the substrate S to be treated near its outer periphery. In this case, the nozzle means has a gas passage in its inside, and plural gas injection ports communicating to the gas passage are arrayed at its upper face.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a CVD apparatus for forming a graphite nanofiber thin film on a substrate.

[0002]

2. Description of the Related Art A graphite nanofiber thin film is formed on a component requiring an electroluminescent element as a substitute for a flat panel display (field emission display) or an electron tube of a CRT, for example. To form a graphite nanofiber thin film, for example, thermal CVD (Chemical vapor d)
An eposition apparatus is used, and such a thermal CVD apparatus is known from Japanese Patent Application No. 2000-89468.

[0003] The thermal CVD apparatus is provided with a vacuum chamber (film forming chamber) which can form a vacuum atmosphere. Inside the vacuum chamber, there is provided a substrate holder on which a substrate made of glass or Si, on which a thin film of Fe or Co is formed, is mounted. In addition, an infrared transmission window made of heat-resistant glass such as quartz glass is provided on the upper wall surface of the vacuum chamber so as to face the substrate to be processed mounted on the substrate holder, and a heating means is provided outside the transmission window. An infrared lamp is provided. Furthermore, a mixed gas supply system for introducing a mixed gas of, for example, carbon monoxide gas and hydrogen gas into the vacuum chamber is connected to the vacuum chamber. Then, while the substrate to be processed is heated by the infrared lamp, 1 is provided on the side wall of the vacuum chamber.
A graphite nanofiber thin film is grown on the substrate by introducing a mixed gas at normal temperature into the vacuum chamber from the gas inlet at the location.

[0004]

The mixed gas introduced into the vacuum chamber has a predetermined temperature (for example, 40 ° C.).
(0 ° C.) or more. For this reason, in the above-mentioned apparatus, although the arrangement position of the gas introduction port which can be provided in the vacuum chamber side wall is appropriately designed, it is difficult to control the film thickness distribution of the graphite nanofiber thin film by introducing such a mixed gas. It is.
In this case, it is conceivable to provide a plurality of gas inlets on the side wall of the vacuum chamber and to introduce a mixed gas into the vacuum chamber from these gas inlets.
Regardless of a substantially square substrate having a size of about 200 mm or a circular substrate having a diameter of about 200 mm, for example, a film thickness distribution of a graphite nanofiber thin film with respect to a large substrate having a size of 1 mx 1 m or a rectangular substrate having a size of A4. It is difficult to appropriately design the arrangement position of the gas inlet so that the gas distribution becomes uniform. In the above-described apparatus, the mixed gas at room temperature is introduced into the vacuum chamber. However, in this case, it takes time for the mixed gas that has reached the substrate to be processed to rise to its reaction temperature (about 450 ° C.). There is a problem that the growth rate of the graphite nanofiber is slow.

In view of the above problems, it is an object of the present invention to achieve a high growth rate of a graphite nanofiber thin film, and furthermore, to obtain a graphite nanofiber having a uniform thickness distribution regardless of the size and outer shape of a substrate to be processed. An object of the present invention is to provide a thermal CVD apparatus capable of forming a nanofiber thin film.

[0006]

In order to solve this problem, a CVD apparatus according to the present invention includes a mixed gas supply system for introducing a mixed gas of a carbon-containing gas and a hydrogen gas into a vacuum chamber. A thermal CVD apparatus that forms a graphite nanofiber thin film on a substrate to be processed by introducing a mixed gas from a mixed gas supply system connected to a gas source outside the vacuum chamber while heating the substrate to be processed,
A gas injection nozzle connected to a mixed gas supply system provided so as to introduce the mixed gas in the vacuum chamber below the height position of the substrate to be processed and to surround the substrate to be processed in the vicinity of the outer periphery thereof The gas ejection nozzle means has a gas flow path therein, and a plurality of gas injection ports communicating with the gas flow path are arranged on the upper surface thereof,
A mixed gas heating means for heating a mixed gas introduced into the vacuum chamber to a predetermined temperature is provided at a position located outside the vacuum chamber of the gas supply system.

According to the present invention, the temperature of the mixed gas introduced into the vacuum chamber can be raised by the gas heating means provided in the mixed gas supply system, and the mixed gas reaching the substrate to be processed can reach the reaction temperature. Since the temperature rises quickly, the growth rate of the graphite nanofiber thin film can be increased. On the other hand, the mixed gas which has been ejected upward from a plurality of gas ejection ports arranged in a row on the upper surface of the gas ejection nozzle means provided so as to surround the substrate to be processed in the vicinity of the outer periphery thereof, Spread evenly over the entire
Then, the substrate descends uniformly downward and reaches uniformly over the entire substrate to be processed. Therefore, even if the substrate to be processed has a relatively large dimension or a rectangular outer shape, A graphite nanofiber thin film having a uniform film thickness distribution can be formed on the substrate to be processed irrespective of the size and outer shape of the substrate to be processed.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIGS. 1 and 2, for example, a thermal CVD apparatus 1 for forming a graphite nanofiber thin film on an A4-size rectangular substrate to be processed S comprises a load lock chamber 11 and a film forming apparatus. A chamber 12 is provided, and the load lock chamber 11 and the film formation chamber 12 are connected via a gate valve 13. The load lock chamber 11 is a substrate S to be processed made of glass, Si, or the like, in which a metal thin film such as Fe or Co is formed on a film forming surface, and is exposed to a vacuum atmosphere.
It plays a role of removing moisture and the like on the surface of the substrate S to be processed. For this reason, the vacuum pump 111
Are connected, and a vacuum gauge 112 for monitoring the degree of vacuum is provided. The load lock chamber 11 has a substrate holder 16 on which the substrate S to be processed is mounted.
A transfer arm 15 for transferring the image is provided. The transfer arm 15 includes a first arm 152 fixed to an upper end of a rotary shaft 151 having a servomotor (not shown),
A second arm 153 pivotally supported at the other end of the arm 152,
A third arm 154 pivotally supported by the other end of the second arm 153 and having a fork-shaped support portion for supporting the substrate holder 16 on which the substrate S to be processed can be mounted from below. Then, the second and third arms 153, 15
By rotating the transfer arm 4, the transfer arm 15 can be extended and contracted. In addition, the rotary shaft 151 can be moved up and down with a short stroke for delivery of the substrate holder 16 on which the substrate S to be processed is mounted. The substrate S to be processed mounted on the substrate holder 16 is housed in the load lock chamber 11 from the outside by the transfer arm 15 and is subjected to a predetermined degree of vacuum (for example, 0.01 Torr).
After evacuation to about r), the gate valve 13 is opened, and the substrate S to be processed is transported together with the substrate holder 16 to the film forming chamber 12 evacuated to a predetermined degree of vacuum (for example, about 0.01 Torr). Then, the transfer arm 15 is returned to the load lock chamber 11 again, and the gate valve 13 is closed.

On the bottom surface of the film forming chamber 12, three columns 121 for mounting a substrate holder 16 on which a substrate S to be processed transferred by the transfer arm 15 is mounted correspond to the area of the substrate holder 16. Are arranged so as to form a substantially triangular shape. Of the columns 121, the column located on the side of the load lock chamber 11 is located in the gap between the fork-shaped support portions of the third arm 154 and serves as a guide for the transport arm 15. In the present embodiment,
Although the substrate holder 16 was transported,
The substrate holder 16 is fixed on the support 121 inside,
The substrate S to be processed may be transported.

An infrared transmission window 122 made of heat-resistant glass such as quartz glass is provided on the upper wall surface of the film forming chamber 12 so as to face the substrate S to be processed mounted on the substrate holder 16. Outside the transmission window 122, a plurality of infrared lamps 17, which are heating means having a predetermined arrangement, are arranged, and heat the substrate to be processed S uniformly over its entire surface. Similarly to the load lock chamber 11, the film forming chamber 12 is provided with a vacuum pump 123 so that a vacuum atmosphere can be formed, and a vacuum gauge 124 for monitoring the degree of vacuum is provided. Has been established. In addition, a pipe bypassing the vacuum pump 123 is connected to the valve 12.
3c is provided.

Further, the mixed gas supply system 1 is
8 are connected. The mixed gas supply system 18 includes a valve 181a, a gas flow controller 181b, a pressure controller 18
1c and a carbon-containing gas supply system 181 connected in series with a carbon-containing gas cylinder 181e such as carbon monoxide via a valve via a valve 181d, a valve 182a to a gas flow regulator 182b, a pressure regulator 182c, and a valve 182d. And a hydrogen gas supply system 182 connected in series to the hydrogen gas cylinder 182e via a gas pipe. Further, the carbon-containing gas supply system 181 and the hydrogen gas supply system 182 are connected to the valves 181a and 182a and the film forming chamber 12
And a mixed gas consisting of a carbon-containing gas and a hydrogen gas is introduced into the film forming chamber 12. Here, the reason why the hydrogen gas is used in addition to the carbon-containing gas to form the graphite nanofiber thin film is because of dilution and catalytic action in the gas phase reaction.

When a mixed gas is introduced into the film forming chamber 12 through a mixed gas supply system 18, the mixed gas is located above the substrate S to be processed as in a conventional thermal CVD apparatus. If a mixed gas is introduced from one gas inlet provided on the side wall, it is difficult to make the film thickness distribution of the graphite nanofiber thin film uniform on a relatively large substrate or a rectangular substrate. Therefore, in the present embodiment, the introduction of the mixed gas is performed below the height position of the substrate S to be processed, and the gas injection nozzle means 19 provided so as to surround the substrate S near the outer periphery thereof. It was decided to do it through.

Referring to FIGS. 2 and 3, the annular gas injection nozzle means 19 has a mixed gas flow path 191 therein, and a plurality of gas injection paths communicating with the gas flow path 191 on its upper surface. The mouths 192 are arranged. On the upper surface of the gas injection nozzle means 19, a mixed gas supply unit 193 having a joint communicating with the gas flow path 191 is opened, and one end of a gas pipe of the mixed gas supply system 18 is connected to the joint. . Here, when the gas injection nozzle means 19 is formed as described above, the gas injection nozzle means 19 itself can be heated together with the substrate S to be processed by the infrared lamp 17. Then, when the surface temperature of the gas injection nozzle means 19 becomes higher than a predetermined temperature, a graphite nanofiber thin film can grow thereon. Since the growth of the graphite nanofiber film causes contamination, it is necessary to frequently clean or replace the gas injection nozzle means 19. For this reason, in the present embodiment, the gas injection nozzle means 19 is formed from copper, which is a metal material having high thermal conductivity, and is arranged in surface contact with the bottom surface of the film forming chamber 12 which can be cooled. In the present embodiment, the gas injection nozzle means 1
Although the ring 9 is annular, any shape can be used as long as the mixed gas can be uniformly injected into the film forming chamber 12. The height of the column 121 on which the substrate holder 16 is placed is ejected upward from the gas injection port 192 of the gas injection nozzle means 19 corresponding to the position of the gas injection nozzle means 19. The size is set so that the mixed gas reaches the substrate S without being heated to a predetermined temperature or higher by the infrared lamp 17.

Incidentally, the mixed gas introduced into the film forming chamber 12 needs to reach the substrate without being heated to a predetermined reaction temperature (450 ° C.) or higher. On the other hand, in order to increase the growth rate of the graphite nanofibers, it is necessary to immediately dissociate the carbon-containing gas of the mixed gas that has reached the target substrate S. For this reason, it is desirable to raise the temperature of the mixed gas introduced into the film formation chamber 12 to a temperature at which the mixed gas immediately reacts upon reaching the substrate S to be processed. Therefore, in the present embodiment, the mixed gas heating unit 2 that heats the mixed gas is provided at a position where the carbon-containing gas supply system 181 and the hydrogen gas supply system 182 in the mixed gas supply system 18 merge.
1 was interposed.

Referring to FIG. 4, mixed gas heating means 21
Has a gas passage 211 through which a mixed gas flows. In the gas passage 211, a plurality of resistance heating coils 212 are provided, and by controlling a current to the resistance heating coil 212, the gas passage is formed. It is configured such that the mixed gas flowing through 211 can be heated to a predetermined temperature. In the present embodiment, the resistance heating coil 212 is provided in the gas passage. However, there is no particular limitation as long as it can heat the mixed gas. For example, an infrared lamp is provided outside along the gas passage. The gas mixture may be heated to a predetermined temperature by the infrared lamp.

Next, a process for forming a graphite nanofiber thin film using the above apparatus will be described.

As the substrate S to be processed, a substrate obtained by depositing Fe with a thickness of 100 nm on a glass substrate by an EB evaporation method is used. The substrate S on which the substrate to be processed S on which Fe is deposited is mounted on the substrate holder 16 from the outside of the load lock chamber 11 and temporarily stored in the load lock chamber 11 by the transfer arm 15, and the vacuum pump 111 is started. The vacuum evacuation is performed to about 0.01 Torr while measuring with the vacuum gauge 112. At the same time, the film forming chamber is also equipped with a vacuum pump 12
3 and start measurement with the vacuum gauge 124
Evacuation is performed until the pressure becomes about rr. After the load lock chamber 11 and the film forming chamber 12 reach a predetermined degree of vacuum,
After a predetermined time has elapsed, the gate valve 13 is opened and the film forming chamber 1 is opened.
The substrate holder 16 on which the substrate S to be processed is mounted is placed on the second substrate holder support column 121. In this state, the main stoppers of the carbon monoxide gas cylinder 181e and the hydrogen gas cylinder 182e are opened, the pressure is adjusted to about 1 atm (absolute pressure) by the pressure regulators 181c and 182c, and the valves 181a and 181c are opened.
182a is opened, and a mixed gas of carbon monoxide gas and hydrogen gas (CO: CO:
H ₂ = 30: 70 gas ratio) was adjusted to about 1000 sccm, and the mixed gas heated to 350 ° C. via the gas heating means 21 was passed through the gas injection nozzle means 19 from below the substrate holder 16 to be processed. It was introduced into the film forming chamber 12 and gas replacement was performed. At this time, the vacuum pump 123 is stopped, and valves 123a and 123 provided before and after the vacuum pump 123 are provided.
b is closed, the valve 123c of the bypass pipe is opened, and the film forming chamber 12 is almost at atmospheric pressure (760 Torr).
r). In this case, the mixed gas was introduced while the substrate S to be processed was heated to 500 ° C. by energizing the infrared lamp 17.

After the pressure in the film forming chamber 12 became atmospheric pressure, a growth reaction of graphite nanofibers was performed on the substrate at 500 ° C. for 10 minutes by a thermal CVD method. When the carbon monoxide gas reaches the substrate to be processed S, the carbon monoxide is dissociated, and the F deposited on the substrate to be processed is removed.
The graphite nanofiber thin film was formed only on the e thin film. Here, the growth rate of the graphite nanofiber thin film by introducing a pre-heated mixed gas is almost four times that of growing the graphite nanofiber thin film by introducing a mixed gas at room temperature. Improved.

[Brief description of the drawings]

FIG. 1 is a diagram schematically showing a configuration of a thermal CVD apparatus of the present invention.

FIG. 2 is a sectional view taken along the line II-II in FIG.

FIG. 3 is a partial perspective view of the gas injection nozzle means.

FIG. 4 is an enlarged sectional view of a portion A in FIG. 1;

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Thermal CVD apparatus 12 Film-forming chamber 17 Infrared lamp 18 Mixed gas supply system 19 Gas injection nozzle means 21 Gas heating means S Substrate to be processed

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Harukuni Furuse 2500 Hagizono, Chigasaki-shi, Kanagawa Japan Vacuum Engineering Co., Ltd. F-term (reference) 4G046 CA01 CA02 CB03 CB08 CC06 CC09 4K030 AA14 AA17 BA27 BB12 BB14 CA06 CA17 EA05 EA06 FA10 HA04 JA02 KA22 KA24 4L037 CS04 FA02 PA03 PA06 PA19

Claims (1)

[Claims] A mixed gas supply system for introducing a mixed gas of a carbon-containing gas and a hydrogen gas into a vacuum chamber, wherein the mixed gas supply system is connected to a gas source outside the vacuum chamber while heating the substrate to be processed by a substrate heating means. A thermal CVD apparatus for forming a graphite nanofiber thin film on a substrate to be processed by introducing a mixed gas from a mixed gas supply system, wherein the introduction of the mixed gas in the vacuum chamber is lower than a height position of the substrate to be processed. This is performed through gas injection nozzle means connected to a mixed gas supply system provided so as to surround the substrate to be processed near its outer periphery, and the gas injection nozzle means has a gas flow path therein. In addition, a plurality of gas injection ports communicating with the gas flow path are arranged in a row on the upper surface thereof, and are introduced into the vacuum chamber at a position located outside the vacuum chamber of the gas supply system. If the gas thermal CVD apparatus, wherein a provided a mixed gas heating means for heating to a predetermined temperature.