JPS6394635A - Device for manufacturing semiconductor - Google Patents

Abstract

PURPOSE:To reduce contamination of a semiconductor substrate with reaction- produced substances by a method wherein an exhaust pipe is attached to the open end of a reaction tube, the other end of the tube is closed, the soaking space of a heating furnace is allowed to extend along the reaction tube as far as the vicinity of the open end, and an exhaust port is provided. CONSTITUTION:A reaction gas is let in through a reaction gas intake port 10 provided at the lower side of a reaction tube 8 and is discharged at the upper end 8a of a U-shape constituting a soaking space. Change in temperature is small in this region and a film formed here by reaction is uniform in its quality and, therefore, its possibility of peeling off the tube wall is low. In the vicinity of an exhaust port 9b remote from an exhaust pipe leadout port 9a, temperature is lower and variable. In this region, the film formed by reaction is uneven in its quality and, therefore, is easier to peel off the tube wall. In a device of this invention, such a region is remote from the exhaust pipe leadout port 9a, and is located at place completely isolated from a semiconductor substrate insertion opening (the open end of the reaction tube 8). It follows therefore that the possibility is quite low of adhesion to a semiconductor substrate 3 of reaction produced substances.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a semiconductor device manufacturing apparatus that performs chemical reaction treatments such as thermal oxidation, diffusion, and vapor phase growth (hereinafter simply referred to as semiconductor manufacturing apparatus). It is related to.

[Conventional technology]

In processing steps such as thermal oxidation, diffusion, and vapor phase growth in the manufacturing process of semiconductor devices such as LSI, a semiconductor substrate is inserted into a heated reaction tube, and a predetermined reaction gas is introduced to perform the processing. In the case of the conventional apparatus shown in FIG. 5 (an example of a vertical type), the reaction products deposited on the inner wall of the reaction tube near the exhaust gas outlet 10 are in an unstable state where they are likely to peel off, and the semiconductor substrate There was a problem in that it adhered to and contaminated semiconductor substrates when they were taken in and out. Recently, as shown in Fig. 6, attempts have been made to solve the above problem by making the reaction tube double and separating the inlet/outlet and outlet 10 for the semiconductor substrate 3, but in this case, a double reaction tube is used. This has the disadvantage that the device is complicated and expensive.

Furthermore, the work of removing and cleaning such a complicated and large-sized reaction tube was an extremely difficult work.

[Problems to be solved by the present invention]

SUMMARY OF THE INVENTION An object of the present invention is to eliminate the above-mentioned conventional drawbacks, and to provide a simple and inexpensive semiconductor fabrication device that causes less contamination of semiconductor substrates by reaction products.

[Means for Solving the Problems and Their Effects] In order to achieve the above object, in the semiconductor manufacturing apparatus of the present invention, an exhaust pipe is provided at the closed end of the reaction tube whose lower end is open and whose upper end is closed. The exhaust pipe is routed in the soaking space of the heating furnace to the vicinity of the open end along the reaction tube, and an exhaust port is provided there. In this way, the reaction gas is introduced from the reaction gas inlet provided at the lower end of the reaction tube, makes a U-turn in the soaking space, and is exhausted. The reaction gas is
Although it is discharged from the upper end side where the temperature is relatively high (forming a soaking space), there is little temperature change in this region and a reaction product with a uniform film quality is formed, so it is less likely to peel off than from the pipe wall.

On the other hand, near the exhaust port, which is far away from the outlet, the temperature decreases and temperature changes occur, resulting in the formation of a reaction product with non-uniform film quality, which tends to cause peeling from the pipe wall. In the structure of the invention, this part is far away from the exhaust pipe outlet and completely separated from the semiconductor substrate insertion port (open end of the reaction tube), so the possibility of adhesion to the semiconductor substrate is extremely low. In this way, according to the present invention, a simple and inexpensive single tube can be used to obtain the same effect as when a double tube is used (FIG. 6).Furthermore, as shown in FIGS. Place the generation electrode in the reaction tube 8.
Plasma cleaning can be performed without removing the reaction tube by inserting it into a sheath (for example, a quartz tube) installed on the outer peripheral wall of the reaction tube and applying a high-frequency voltage (however, at this time, the inside of the reaction tube is in a vacuum). The pressure must be reduced by evacuation). By using the sheath in this way, it is possible to prevent leakage between the electrodes and between the electrode and the heater, and at the same time, it is possible to reliably bring the electrode into close contact with the reaction tube. Furthermore, by introducing an inert gas such as nitrogen through a thin tube or the like from one end of the sheath, oxidative consumption of the electrode material (for example, isotropic carbon coated with SiC) can be prevented.

〔Example〕

Embodiments of the present invention will be described in detail below with reference to the drawings.

To facilitate understanding, FIG. 5 shows a conventional vertical apparatus using a single reaction tube, and FIG. 6 shows a conventional vertical apparatus using double tubes.

FIG. 1 shows an embodiment of the present invention. In the figure, an exhaust pipe outlet 9a is provided at the closed upper end 8a of the reaction tube, and the exhaust pipe 9 is routed along the reaction tube 8 in the soaking space of the heating furnace 1 to near the open lower end 8b. and exhaust port 9b there.
will be established.

In this way, the reaction gas is introduced from the reaction gas inlet 10 provided at the lower end of the reaction tube, makes a U-turn in the soaking space, and is exhausted. The reaction gas g is discharged from the upper end side 8a, which has a relatively high temperature and forms a soaking space, but there is little temperature change in this region (because a uniform film-like reaction product is formed, It is difficult to peel off.On the other hand,
Near the exhaust port 9b, which is further away from the outlet 9a, the temperature decreases and temperature changes occur, resulting in the formation of a reaction product with non-uniform film quality, which makes peeling from the tube wall more likely. In the structure of the invention, this part is far away from the exhaust pipe outlet 9a and is located far from the semiconductor substrate insertion port (
Since the location is completely separated from the open end of the reaction tube, there is very little possibility that it will adhere to the semiconductor substrate 3. The exhaust pipe 9 disposed along the reaction tube is fixed to the reaction tube 8 by fusion or the like for stability. Although the above embodiments have been shown for a vertical furnace, they can also be applied to a horizontal furnace. FIGS. 1 and 2 show examples of the arrangement of electrodes 11 for plasma cleaning of reaction tubes. These electrodes are housed in a sheath 12 and connected to a high frequency power source 13 to which a high frequency voltage is applied. At this time, if the pressure inside the reaction tube 8 is sufficiently reduced, plasma is generated and the inside of the reaction tube is cleaned.

In the connection example shown in FIG. 2, voltages of opposite polarity are applied to adjacent electrodes, and therefore plasma is generated between the adjacent electrodes, which is convenient for cleaning the inner wall of the reaction tube.

In the above embodiments, rod-shaped electrodes are shown, but plate-shaped electrodes or net-shaped electrodes are also applicable.

Furthermore, when exhausting from several locations in order to obtain an optimal flow of reaction gas, exhaust pipes can be taken out as shown in FIG. 3 (fluorescent tube type) or FIG. 4 (quadruped type).

[Brief explanation of the drawing]

1 to 4 show an embodiment to which the present invention is applied. Fig. 1 is a vertical cross-sectional view showing an embodiment in which the present invention is applied to a vertical furnace, Fig. 2 is a top plan view showing an example of connection when a plasma electrode is provided, and Fig. 3 is a reaction tube. An example is shown in which a fluorescent tube-like exhaust pipe outlet is attached to the upper end, and FIG. 4 is an example in which a quadruped-like outlet is attached. FIG. 5 shows an example in which a conventional single reaction tube is used, and FIG. 6 shows an example in which a conventional double reaction tube is used. 1... Heating furnace IA... Furnace body 1B... Heater 2... Semiconductor substrate holder 3... Semiconductor substrate 4... Support stand 5... Support shaft 6. ... Rotation drive mechanism 7 ... Vacuum flange 8 ... Reaction tube 8a ... Closed reaction tube upper end 8b ... Open reaction tube lower end 9 ... Exhaust pipe 9a ...Exhaust pipe outlet 9b...Exhaust pipe gas discharge port 10...Gas inlet port 11...Plasma electrode 12...Sheath 13...High frequency power source g...Reaction Gas flow OR...0 ring Figure 3 4th Patent Office Commissioner Kunio Ogawa 1. Indication of the case 1986 Patent Application No. 239088 3, Person making the amendment Relationship with the case Patent applicant Address Postal code 214 6-20-3 Nagao, Tama-ku, Kawasaki City, Kanagawa Prefecture Name 5, Drawing subject to amendment 6 , the details of the amendment are as per the attached sheet.

Claims (1)

[Scope of Claims] 1) A semiconductor manufacturing device comprising a reaction tube having a reaction gas inlet and an outlet, and a heating furnace covering the reaction tube, one end of which is open and the other end of which is closed. An exhaust pipe is provided at the closed end of the reaction tube, and the exhaust pipe is routed along the reaction tube in the soaking space of the heating furnace to near the open end, and an exhaust port is provided. A semiconductor manufacturing device characterized by being provided with. 2) The semiconductor manufacturing apparatus according to claim 1, wherein an electrode for generating plasma is disposed on the outer peripheral wall of the reaction tube for self-cleaning of the reaction tube and the exhaust pipe.