JPH03106018A - Pressure-reduced chemical vapor growth device - Google Patents

Abstract

PURPOSE:To suppress the amount of oxygen carried into a furnace when wafers are brought into the furnace and also to suppress the residence air between each wafer by a method when in inert gas is introduced from the side of the rear end of the furnace, and an inert gas substitution mechanisms are provided on both the immediately front part of the furnace and the part in the vicinity of the furnace inlet. CONSTITUTION:A furnace pressure control valve 7 is closed when a wafer is brought into a furnace, an inert gas introducing valve 8, which is used to prevent the penetration of the atmospheric air into the furnace, is opened and the inert gas is allowed to flow in the furnace toward its opening end. At the same time, inert gas is permitted to flow out toward the wafers in the furnace from the inert gas blowing-out part 9 located outside the furnace, and the atmospheric air between wafers is substituted with the inert gas to a certain extent. Besides, a double substitution mechanisms, with which inert gas is permitted to blow-out toward the exhaust part 12 in the furnace from the inert gas blow-out part 11 in the furnace and a little quantity of the air stagnated between each wafer is substituted with inert gas, is provided. As a result, the quantity of oxygen brought into the furnace when the wafers are placed into the furnace and the air stagnated between wafers can be suppressed.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a reduced-pressure chemical vapor deposition apparatus, in particular, to a reduced pressure chemical vapor deposition apparatus, in which a weno 1 is placed in the furnace at a raised temperature and the inside of the furnace is opened to the atmosphere, and then the inside of the furnace is opened to the atmosphere. This invention relates to a reduced pressure chemical vapor phase control device that performs a certain membrane treatment under reduced pressure.

[Conventional technology]

FIG. 2 shows a cross-sectional view of a conventional reduced pressure chemical vapor deposition apparatus.

In the figure, a large number of semiconductor wafers 6 to be processed are set in a wafer loading jig 5 with a cap 3 attached to the furnace core tube 1, and the furnace is loaded from the furnace mouth, and the furnace mouth is sealed with the cap 3. Then, a reaction gas is introduced from a reaction gas introduction pipe 4 provided in the cap 3, and a desired film is elongated on the surface of the wafer 6 by a chemical reaction of the reaction gas. In addition, when using a single wafer furnace, open the valve 8 of the inert gas introduction pipe installed at the rear end of the furnace opposite to the furnace mouth to create a flow of inert gas from the rear end of the furnace to the furnace mouth. This prevents air from entering the furnace. In the figure, 2 is a heater for raising the temperature inside the furnace, 7 is a valve for controlling the pressure inside the furnace, and 10 is an exhaust part.

[Problem to be solved by the invention]

In the conventional low-pressure chemical vapor deposition apparatus described above, charging is performed at a high temperature close to that of a certain film temperature and in an open atmosphere, so oxygen from the atmosphere enters the furnace and the wafer surface is heated. sometimes gradually oxidized.

Therefore, in order to prevent this oxidation, the cap 3 for sealing the furnace core tube is removed and opened, and at the same time, the inert gas introduction valve 8 is opened to introduce inert gas from the rear end of the furnace. Because the opening area of the furnace mouth was extremely large, it was not possible to sufficiently prevent air from entering. In addition, when entering the furnace, the wafer surface is perpendicular or nearly perpendicular to the axis of the furnace core tube, blocking the flow direction of the inert gas introduced from the rear end of the furnace, and the area near the furnace inner wall is somewhat unstable. Although the atmosphere is replaced with an active gas, there is a drawback that the air remains between each wafer and is brought into the furnace, resulting in oxidation of the wafer surface.

[Means to solve the problem]

In the reduced pressure chemical vapor deposition apparatus of the present invention, an inert gas blowout part and an exhaust part are provided in pairs near the opening of the furnace core tube so that the flow of the inert gas is approximately parallel to each wafer surface. Immediately before this, the stagnant atmosphere between each wafer is replaced with inert gas. Ru.

Furthermore, even if you do this, air will be drawn in at the same time when the inert gas is blown out, and a small amount of air will remain between each wafer. It has a double inert gas replacement structure with a Therefore, the oxygen remaining between each wafer, which was overlooked in the past, is also completely replaced with inert gas.

〔Example〕

Next, the present invention will be explained with reference to the drawings.

FIG. 1 is a sectional view of an embodiment of the present invention. In FIG. 1, a furnace core tube 1 is heated by a heater 2, and when a wafer 6 is placed in the furnace, a cap 3 moves upward together with a wafer loading jig 5 to seal the open end of the furnace core tube. During film growth, a reaction gas is introduced from the reaction gas inlet 4, and the furnace pressure is adjusted by the furnace pressure control valve 7. Here, when one wafer is in the furnace (ascending), the furnace pressure control valve 7
is closed, and an inert gas introduction valve 8 for preventing atmospheric air from entering the furnace opens, and the inert gas flows inside the furnace toward the open end along the arrow.

At the same time, inert gas is blown out from the outside inert gas blowing section 9 toward the wafers being placed in the furnace, and is exhausted from the outside exhaust section 10 installed on the extension line of the inert gas, which slightly entrains the atmosphere near the furnace mouth. However, the atmosphere between each wafer is replaced to some extent with an inert gas. Furthermore, inert gas is blown out in the same way from the inert gas blowing section 11 in the furnace, and the inert gas is evacuated at the in-furnace exhaust section 12 installed on the extension line of the inert gas, and the atmosphere slightly stagnant between each wafer is replaced with the inert gas. A double replacement mechanism is provided.

〔Effect of the invention〕

As explained above, the present invention introduces an inert gas from the rear end of the furnace and has a dual inert gas exchange mechanism in the area just before the furnace mouth and in the vicinity of the furnace mouth. It is possible to significantly reduce the amount of oxygen brought into the furnace at the time of processing, and the amount of air (especially oxygen) stagnant between each wafer is also suppressed, which has the effect of sufficiently suppressing oxidation of the wafer surface when entering the furnace. There is. Therefore, for example, when polycrystalline silicon is placed on a silicon wafer to establish electrical conduction between the two, silicon dioxide is formed between the silicon wafer surface and polycrystalline silicon due to the intrusion of oxygen during the furnace, and the electrical conduction between the two is established. This can solve the problem of preventing

[Brief explanation of drawings]

FIG. 1 is a sectional view of an embodiment of the present invention, and FIG. 2 is a sectional view of a conventional reduced pressure chemical vapor phase elongation apparatus. 1... Furnace core tube, 2... Heater, 3...
... Cap, 4 ... Reaction gas introduction part, 5
...Wafer loading jig, 6...Wafer 7...Furnace pressure control valve, 8...
... Valve for inert gas introduction, 9 ... Inert gas blowing part outside the furnace, 1o ... Exhaust part outside the furnace, 11
...Furnace inert gas blowing section, 12...
...Furnace exhaust section.

Claims (1)

[Claims] In a reduced pressure chemical vapor deposition apparatus using a furnace core tube, a double layer is used to replace the stagnant atmosphere between a large number of semiconductor wafers set in a loading jig and entered into the furnace core tube with inert gas. A reduced pressure chemical vapor deposition apparatus, characterized in that an inert gas blowing and exhaust mechanism is provided near the furnace mouth of the furnace core tube.