JPS6148583B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an externally heated plasma chemical vapor deposition apparatus and an externally heated chemical vapor deposition apparatus used for manufacturing semiconductor substrates and substrates as materials for solar cells. More specifically, silicon nitride (SiN), silicate glass (SiO ₂ ), or phosphosilicate glass (PSG) are used as interlayer insulating films and final protective films for semiconductor substrates, and amorphous silicon is used as a material for solar cells. When producing a thin film of amorphous silicon carbide (Si _x C _1-x ) on a substrate, the substrate to be processed is inserted into a reaction tube that has already been heated to the reaction temperature, and a chemical vapor is generated using a reaction gas. Plasma chemical vapor deposition in conjunction with phase growth or glow discharge has recently become popular due to its shortened operating time.

FIG. 1 shows the configuration of a conventionally commonly used apparatus, and the figure shows a plasma chemical vapor deposition apparatus. In the case of a chemical vapor deposition apparatus that does not use plasma, there is no electric circuit for introducing high-frequency power, and the other aspects are the same, so the following explanation will be given for the plasma chemical vapor deposition apparatus.

In the figure, reference numeral 1 denotes an annular heater surrounding a reaction tube 2, and the reaction tube 2 has one end that is wide open as an inlet/outlet for contents, and the other end is constricted and has an exhaust hole 2-1 opened therein. Reference numeral 3 denotes a boat made of heat-resistant insulator such as quartz, the bottom surface of which is shaped to match the lower side surface of the reaction tube, and the substrate holding electrode 4 on the top surface aligned with the surface perpendicular to the tube axis of the reaction tube. A plurality of sheets are held at substantially equal intervals.
Reference numeral 5 denotes a lid provided at the inlet/outlet for the contents of the reaction tube, and a connecting rod 5-1 connected to the boat is attached to the inner surface of the lid.
Two terminals 14 are provided through the lid to supply high frequency power to the substrate holding electrode. The substrate holding electrodes are connected alternately to every other substrate using lead wires 13 from inside these terminals to form groups of substrate holding electrodes facing each other. Reference numeral 6 denotes a reaction gas introduction ring provided between the contents inlet/outlet of the reaction tube and the lid, and a reaction gas introduction pipe 6-1 provided with a valve is provided. 7 is an exhaust pump that exhausts the reaction tube from the exhaust hole 2-1.

In order to perform chemical vapor deposition using such conventional equipment, the substrate is loaded onto the substrate holding electrode (or substrate holding plate) that stands upright on the boat at room temperature, and the substrate is already heated to the reaction temperature required for vapor phase growth. The substrate is then inserted into a reaction tube that has been heated to a temperature of 100.degree. C. and left until the substrate reaches a predetermined reaction temperature. However, in this state, the reaction tube is filled with air, and as the substrate temperature rises, the substrate surface becomes oxidized. For this reason, it has the disadvantage that it cannot be used for producing substrates that are easily oxidized or films that are easily oxidized.

In order to alleviate this drawback to some extent, a method has been attempted in which the air is exhausted immediately after inserting the board, without waiting for the temperature of the board to rise. In this case, most of the means of heat conduction through convection within the reaction tube are taken away, and since the heat capacity of not only the substrate but also the substrate holding electrode and boat is large, it takes until the temperature rises to a predetermined temperature and becomes stable. It takes a long time, and previously required more than 40 minutes.

After the temperature stabilizes as described above, the reaction gas is injected from the reaction gas introduction tube in 6-1 above, and while maintaining a predetermined degree of vacuum, plasma is generated between each electrode to form a film on the substrate. It is something. The only thing that is directly required in this process is the thin film generation process, and the shorter the time for other temperature stabilization and the time for the temperature to drop to room temperature after the formation is completed, the better.
This time was a major obstacle to improving productivity.

The present invention was made to solve these problems, and provides an externally heated plasma chemical vapor deposition apparatus and an externally heated reduced pressure chemical vapor deposition apparatus that can significantly improve productivity. . The case of using plasma will be explained in detail below with reference to the drawings. If plasma is not used, there is no relationship with high frequency power, and the other things are the same, so the explanation will be omitted.

FIG. 2 is a longitudinal sectional view of the reaction tube portion of the chemical vapor deposition apparatus of the present invention. In the figure, 15 is an external reaction tube, 12 is a lid provided at the entrance and exit for the contents of the external reaction tube, and inside this lid is an internal reaction tube with a tube axis that substantially matches the tube axis of the external reaction tube. A reaction gas inlet 12-1 and an inert gas inlet 12-2 are connected from the inside of the lid to the outside or the periphery at a position corresponding to the inner part of the internal reaction tube of the lid. In addition, two terminals 14 for high frequency power are provided to penetrate through both sides of the lid. Furthermore, a boat 16-1 made of a heat-resistant insulating material such as quartz is fixed to the lower surface of the tube wall so as to straddle approximately the center in the axial direction of the internal reaction tube. Substrate holding electrodes 4 having surfaces perpendicular to the tube axis are provided at substantially equal intervals. In addition, the internal reaction tube wall above the substrate holding electrode has a large opening, and a canopy 18 is used to hold the substrate.
It is closed except when entering and leaving 1. Further, the end of the inner reaction tube opposite to the lid 12 is formed into a narrow exhaust hole 16-2 with a reduced diameter and opens into the outer reaction tube. Legs 16-3 are provided on the lower side of the outer periphery of the inner reaction tube and can be held in contact with the outer reaction tube. These legs are not fixed legs, and may be rollers or other vehicles. Reference numeral 17 denotes a heater for heating an inert gas, and the inert gas outlet 17-1 of this heater and the inert gas inlet 12-2 are connected by a connecting pipe 19 having a valve. The outside of the reaction gas inlet 12-1 is connected to a reaction gas supply source through a connecting pipe 20 having a valve. In addition, an exhaust pump 7 is installed at the end of the external reaction tube opposite to the content inlet/outlet.
is connected.

Next, the operation of the apparatus of the present invention will be explained.

First, before loading the substrates, the heater 1 is energized to raise the external reaction tube to a predetermined reaction temperature. Next, unheated inert gas (generally nitrogen gas) is blown into the internal reaction tube pulled out from the external reaction tube through the inert gas inlet to replace the air inside. After that, remove the canopy 18 and
1 is loaded onto the substrate holding electrode, the opening is closed with a canopy, the inner reaction tube is inserted into the already heated outer reaction tube, the lid 12 is fixed to the outer reaction tube, and the inert gas heating heater 17 The inert gas being blown is also heated to a high temperature by energizing it.

When the substrate reaches a predetermined reaction temperature in this state, the blowing of the inert gas is stopped, and the reaction gas is introduced from the reaction gas inlet 12-1 while the exhaust pump 7 is operated. At this time, the atmospheric pressure inside the internal reaction tube (same as inside the external reaction tube) is maintained at a predetermined pressure by adjusting the displacement amount of the exhaust pump and the amount of introduced reaction gas. When this state is reached, terminal 14
High frequency power is applied to the substrate holding electrode to generate plasma and grow a thin film.

When the specified thin film growth is completed, the application of high-frequency power and the introduction of the reaction gas are stopped, and after replacing the reaction gas with unheated inert gas blown into the inert gas inlet, the exhaust pump is stopped, and the internal reaction tube is closed. It is pulled out from the external reaction tube and allowed to cool to room temperature. After that, just remove the canopy and take out the board.

The above procedure replaces the air with inert gas before the substrate reaches a high temperature, and since it is not exposed to air in the high temperature state immediately after film growth, the substrate and the thin film after growth are not oxidized. .

In addition, since high-temperature inert gas is blown into the external reactor after loading the substrate, heat transfer from the annular heater is also added due to the heat of this inert gas, radiant heat from the annular heater, and convection of the inert gas. So,
The substrate rapidly rises to a predetermined temperature.

According to the example, in the conventional external heating type, the exhaust air is exhausted immediately after inserting the substrate, so it takes 40 to 60 minutes to stabilize at the reaction temperature. In the apparatus of the present invention, this time of 5 minutes was sufficient.

Furthermore, depending on the type of reaction gas, it may be preferable to use a chemically stable material such as a molybdenum wire for the lead wire. However, molybdenum and the like are easily oxidized, making it difficult to use them in conventional devices, but in the device of the present invention, there is no air present when the temperature reaches high temperatures, so there is no problem in using them.

As described above, according to the apparatus of the present invention, the time required for preparatory work and post-processing work before and after thin film growth can be significantly shortened, making it possible to greatly contribute to shortening the overall process time, resulting in practical effects. is extremely large.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a conventional plasma chemical vapor deposition apparatus. FIG. 2 is a longitudinal sectional view of the reaction tube portion of the plasma chemical vapor deposition apparatus of the present invention. In the figure, 1 is an annular heater, 2 is a reaction tube, 4 is a substrate holding electrode, 5 is a lid, 15 is an external reaction tube, 12
16 is an inner reaction tube, 17 is an inert gas heater, and 18 is a canopy of the inner reaction tube.

Claims (1)

[Claims] 1. In an externally heated chemical vapor deposition apparatus for producing a semiconductor compound on the surface of a semiconductor substrate, one end is opened as an inlet/outlet for contents, and the other end is connected to an exhaust pump as an exhaust port. and an inner reaction tube that is fixed to the lid of the content inlet/outlet of the outer reaction tube and inserted into the outer reaction tube substantially coaxially with the outer reaction tube, and the inner reaction tube has an inner tube. A boat is provided fixedly attached to the bottom surface, a plurality of substrate holding plates having vertical surfaces substantially equally spaced on the boat, and a covered opening bored above the plurality of substrate holding plates. An inert gas inlet and a reaction gas inlet are provided in the lid of the content inlet and outlet of the outer reaction tube so as to penetrate into the inner reaction tube, and an inert gas inlet is provided outside the inert gas inlet. 1. A reaction tube for an externally heated chemical vapor deposition apparatus, comprising an active gas heater and an inert gas inlet pipe connecting the inert gas inlet and the inert gas heater. 2. In an externally heated chemical vapor deposition apparatus that generates a semiconductor compound on the surface of a semiconductor substrate, an external reaction tube has one end opened as an inlet and an inlet for contents, and the other end is connected to an exhaust pump as an exhaust port, and this external reaction tube. an inner reaction tube fixed to the lid of the content inlet/outlet of the tube and inserted into the outer reaction tube substantially coaxially with the outer reaction tube; a boat, and two terminals having vertical surfaces substantially equally spaced on the boat and provided through the lid, each of which is electrically connected to every other terminal separately by a lead wire. A plurality of substrate holding electrodes configured into two groups and an opening with a lid formed above the plurality of substrate holding electrodes are provided, and the lid of the contents entrance and exit of the external reaction tube is provided with a lid of the inner reaction tube. An inert gas inlet and a reactive gas inlet are provided so as to penetrate inside the inert gas inlet, and an inert gas heater is provided outside the inert gas inlet, and an inert gas inlet and an inert gas inlet are provided outside the inert gas inlet. A reaction tube for an externally heated chemical vapor deposition apparatus, characterized by comprising an inert gas introduction tube connecting between gas heating heaters.