JPS6012995B2 - Method and apparatus for coating a graphite carbon plate with a densified silicon carbide film - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method and apparatus for coating a graphite carbon plate with a densified silicon carbide film, and more particularly, for coating a semiconductor wafer in a semiconductor vapor phase growth apparatus. The present invention relates to a method and apparatus for manufacturing the heating plate used.

Conventionally, in order to form such a heating plate, a graphite carbon plate was placed in a reactor and the inside of the reactor was heated to 130 mm.
A silicon carbide film is formed by vapor phase growth on the graphite carbon slope by heating to a high temperature of 0 qo or more, and the silicon carbide film thus formed is further heated to a high temperature of 1300 qo or more.
A method of making the silicon carbide film densified by heat treatment at higher temperatures was being explored.

The reason why the silicon carbide film is made so dense is that if there are pinholes in it, the contaminant gas contained in the graphite carbon as the base will pass through those pinholes, as described above. It can enter various grown films formed in the reactor of a semiconductor vapor phase growth apparatus on semiconductor wafers that have been heated on a heating slope, thereby deteriorating the quality of those grown films. Because it will be. By the way, in recent years, large wafers with a diameter of about 76.2 to 101.6 inches (3 to 4 inches) have been used, and it is possible to print a desired number of such large wafers. In order to achieve this, the heating plate mentioned above must also be made correspondingly large.

However, in order to form such a large heating plate, if a high temperature of 1,300 degrees Celsius or more is used as in the conventional method described above, a heating power source with a very large capacity is required. As a result, the reactor also became larger, and if the diameter of the heating plate increased by 50 mm, the reactor would have to be extremely large, making it virtually difficult to manufacture. Even if it were possible, such a furnace would be very expensive and the resulting heating plate would also be expensive. This is because the conventional method described above uses a high temperature of 1300 oo or more. Accordingly, the present invention provides a method for depositing a silicon carbide film on a graphite carbon plate at a relatively low temperature without using such high temperatures, and densifying the film at a low temperature. The object of the present invention is to provide a method and apparatus that can avoid all the problems found in the conventional methods. Embodiments of the invention will now be described with reference to the drawings, which schematically show an embodiment of an apparatus according to the invention with which the method of the invention can be carried out.

In the drawings, 1 is a reaction chamber wall defining a reaction chamber 2,
The reaction chamber wall 1 is placed on a base 3 and constitutes a cylindrical body open at the upper end. Reaction chamber wall 1
A reaction chamber bell jar 4, which can be opened and closed by any suitable elevating mechanism (not shown), is mounted on the upper end surface. It's like it's sealed. Reference numeral 5 denotes a reaction gas injection nozzle that is thrust into the reaction chamber 2 from the base 3, and this injection nozzle 5 has a double-tube structure in a portion below its injection hole; The outer tubular body 6 is configured to support a graphite carbon plate 7, which will be described later, in a horizontal plane perpendicular to the ruts of the injection nozzles 5 within the reaction chamber 2, as shown in the figure.

Furthermore, the lower end part 1 of the double pipe structure has an injection nozzle 5.
and a motor 8 for rotating the outer tubular body 6 and the outer tubular body 6 together.
are connected via a suitable gear mechanism 9 and rotating shaft 8a. Reference numeral 11 denotes a resistance heater provided on the base 3 in the reaction chamber 2 and around the injection nozzle 5.

At the lower end of the injection nozzle 5 extending downward through the rotating shaft 10, a reactant gas supply source 12a and a C ratio supply source 12b, for example, a SiH4 (or a mixed gas of SIC14 and Ar (or He)) supply source 12b are provided. and an inert gas supply V source 12c, such as N2, are connected via suitable valves 13 to direct the reactant gas to the injection nozzle 5.
When the injection nozzle 5 rotates, the liquid is radially injected into the reaction chamber 2 from the injection hole at the upper end of the reaction chamber 2 as shown by the arrows. In addition, the base 3 is provided with exhaust holes 14a and 14b in the reaction chamber 2, and the intake side of a pump 17 is connected to these exhaust holes 14a and 14b via a lotus pipe 15 and a valve 16. The exhaust side of the pump 17 is connected to the lotus pipe 15 via a valve 18. Furthermore, in the embodiment, a plate-shaped lower electrode 19a is provided above the resistance heater 11 in the reaction chamber 2, and is positioned in a horizontal plane perpendicular to the axis of the injection nozzle 5. Above 19a and at a position higher than the upper end of the injection nozzle 5, a plate-shaped upper electrode 19b is similarly attached to the inner surface of the bell jar 4 in parallel and spaced relationship with the lower electrode 19a.

Both electrodes 19a and 19b are connected to a high frequency oscillator 20 of, for example, 500 W, provided outside the reaction chamber 2Z, via conductors 21a and 21b, respectively.
In this case, it is preferable that the lower electrode 19a provided directly above the resistance heater 11 is provided with a barrier hole Z as indicated by 19' over its entire length, for example.
In this way, heat transfer from the resistance heater 1 to the graphite carbon plate 7 can be made more efficient. Further, the upper electrode 19b is provided with, for example, about 2 parts, which are extended in the radial direction with respect to the graphite carboxylate plate 7.
A slit 19 having a width similar to that of the side and an appropriate length is provided. Furthermore, the laser beam 22 is transmitted through the window 4b and slit 19b' formed in the belljar 4.
A laser beam light source 22 capable of irradiating the upper surface of the graphite carbon plate 7 with a laser beam light source 22 is mounted on the bell jar 4 outside the reaction chamber 2. This laser beam light source 22 is constructed so that the laser beam emitted therefrom can be caused to reciprocate and scan the upper surface of the graphite carbon plate 7 in the radial direction and over its radial length. The method of the present invention can be carried out by way of example using an apparatus having the configuration described above, and an example of the method of the present invention will now be described.

In the method of the present invention, as shown in the figure, a graphite carbon plate 7 is placed on the above-mentioned outer tubular body 6, and after the bell jar 4 is sealed, the inside of the reaction chamber 2 is pumped, for example, by 5× Reduce pressure to 10- orr. In that case, the graphite carbon plate 7 is heated by the resistance heater 11 to a relatively low temperature of about 300 to 500°C. In this state, while being evacuated by the pump 17, the reaction gas from the reaction gas supply sources 12a and 12b is injected into the reaction chamber 2 as shown by the arrow through the injection nozzle 5 rotated by the motor 8, and at the same time, the high frequency oscillator For example, a high frequency of about 13.58 M is applied between the lower electrode 19a and the upper electrode 19b from 20, thereby generating plasma between both electrodes, and the plasma is used to cause the injection into the reaction chamber 2 from the injection nozzle 5 as described above. The injected reactive gas, eg, SiH4 or SIC14, and CH4 gas are ionized, and a silicon carbide film (not shown) is deposited over the entire top and surrounding surfaces of graphite carbon plate 7. In this case, as mentioned above, the graphite carbon plate 7 is
The silicon carbide film forming reaction is promoted by heating to a temperature of about 0 to 500°C. Thus, by rotating the graphite carbon plate 7 as described above during the reaction, the silicon carbide film is deposited with a substantially uniform thickness over the entire upper surface of the graphite carbon plate 7. Next, after completing the formation of the silicon carbide film in this way, the supply of reaction gas to the reaction chamber 2 is stopped, the pump 17 is stopped, and this time N2
N2 gas is supplied from the gas supply source 12c into the reaction chamber 2 to return the inside of the reaction chamber 2 to normal pressure, for example about 76 orr.

Next, the silicon carbide film on the graphite carbon plate 7, which is being rotated and cooled as described above, is
A laser beam source 22 irradiates the graphite carbon plate 7 with a reciprocating laser beam through the window 4b of the bell jar 4 and the slit 19b' provided in the upper electrode 19b and in the radial direction of the graphite carbon plate 7. When the laser beam is irradiated in this way, the surface of the silicon carbide film on the graphite carbon plate 7 is melted and crystallized, and as a result, the silicon carbide film becomes densified and virtually no pinholes are formed. It becomes something that does not exist. After completing the so-called annealing process for the silicon carbide film deposited on the upper surface of the graphite carbon plate 7, the laser beam irradiation is stopped and the graphite carbon plate 7 is turned over to form the outer tubular shape described above. It is reattached to the body 6 in the same manner as described above, and the other surface of the graphite carbon plate 7 is heated at a relatively low temperature of about 300 to 500 °C in exactly the same manner as described above. A silicon carbide film is deposited, and the silicon carbide film is subjected to an IJ treatment using a laser beam. In order to further complete the heating plate formed by coating the graphite carbide plate 7 with a densified silicon carbide film, Si, It is only necessary to deposit a film of Si4N4 or Si02, and it is readily apparent that the deposition of such an additional film can also be realized by the method of the present invention using the apparatus shown in the drawings. Probably. As understood from the above explanation, according to the present invention, unlike the conventional method,
At most 300 qo or more without using high temperatures of 300 qo or more
Since the silicon carbide film can be deposited at a relatively low temperature of ~500°C, contamination of impurities can be minimized compared to conventional methods that involve high-temperature treatment, and it is also possible to deposit graphite films at relatively low temperatures. Since the silicon carbide film deposited on the carbon plate is densified by irradiation without any heat treatment, pinholes are virtually completely eliminated. This results in densification.

In addition, as mentioned above, since relatively low temperatures are used, the required heating power supply capacity is small, and the furnace capacity is also small, which makes the manufacturing cost of the furnace unnecessarily high. This will no longer happen. Furthermore,
In the present invention, a graphite carbon plate is rotatably arranged in a reaction chamber, and a silicon carbide film is formed and laser beam irradiation is performed while rotating this graphite carbon plate. In this process, the silicon carbide film is densified by scanning the laser beam in the radial direction of the rotating graphite carbon plate, so that the silicon carbide film can be made to have a uniform thickness and uniform densification. Various excellent benefits can be obtained, such as those that can be obtained with

[Brief explanation of drawings]

The drawing is a schematic illustration of an apparatus according to an embodiment of the invention. In the drawing, 2 is a reaction chamber, 4 is a bell jar, 4b is a window,
5 is an injection nozzle, 6 is an outer tubular body, 7 is a graphite carbon plate mounted on it, 11 is a resistance heater,
12a and 12b are a combined reactive gas supply source, 12c is an inert gas supply source, 17 is an exhaust pump, 19a and 19b are electrodes for plasma formation, 19a' is a through hole, 19b' is a slit, 20 is a high frequency oscillator, 22 is the laser beam source, 2
2a indicates the laser beam.

Claims (1)

[Scope of Claims] 1. A graphite carbon plate is rotatably arranged in a reduced pressure reaction chamber, and the graphite carbon plate is heated to a predetermined relatively low temperature, and then the graphite carbon plate is heated to a predetermined relatively low temperature. While rotating the reaction chamber, a reaction gas for forming a silicon carbide film is introduced into the reaction chamber from outside the reaction chamber, and a plasma is generated in the space in the reaction chamber where the graphite carbon plate is present. A silicon carbide film is formed on the graphite carbon plate by acting on the reaction gas, and then an inert gas is introduced into the reaction chamber to bring the inside of the reaction chamber to approximately normal pressure. While rotating the graphite carbon plate, the silicon carbide film formed on the graphite carbon plate is irradiated with a laser beam while scanning in the radial direction of the graphite carbon plate to densify the silicon carbide film. A method of coating a graphite carbon plate with a densified silicon carbide film. 2. A reaction chamber having a bell gear that can be opened and closed, a means for reducing the pressure inside the reaction chamber, a rotatable tubular injection nozzle means provided in the reaction chamber, and a device configured to rotate integrally with the tubular injection nozzle means. and retaining means adapted to hold the graphite carbon plate in a substantially concentric relation to the tubular injection nozzle means in a horizontal plane substantially perpendicular to the axis of the tubular injection nozzle means; In an apparatus comprising a resistance heating means provided in a room around the injection nozzle means, and means for selectively supplying a reaction gas and an inert gas into the reaction chamber, graphite in the reaction chamber is provided. a pair of plate-shaped electrodes for forming plasma in a space where the carbon plate is arranged; a high-frequency oscillator connected to the pair of plate-shaped electrodes; 1. An apparatus for coating a graphite carbon plate with a densified silicon carbide film, comprising a laser beam irradiation means capable of irradiating a laser beam while scanning the plate. 3. In the device according to claim 2, said 1
A device for coating a graphite carbon plate with a densified silicon carbide film, in which one of the pair of plate-shaped electrodes is provided with a slit that allows scanning irradiation with the laser beam. 4. In the device according to claim 2 or 3, the other of the plate electrodes is provided with an opening for efficiently transmitting heat from the resistance heater means to the graphite carbon plate. A device that coats a graphite carbon plate with pores formed with a dense silicon carbide film.