JPH069488Y2 - Airtight seal cooling device at the end of the reaction tube - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field to which the Invention belongs) The present invention is a low pressure CVD (chemical vapor deposition) apparatus used for forming a thin film on a semiconductor substrate (hereinafter referred to as a wafer), and a reaction tube of a diffusion apparatus. The present invention relates to a cooling device for airtight seals at both ends.

(Prior Art) For example, a reaction tube used for producing a thin film on a wafer in a low pressure CVD apparatus needs to be hermetically sealed at both ends in order to reduce the pressure inside the reaction tube. However, since the reaction tube is kept at a high temperature by a heater outside the reaction tube, a heat-resistant rubber packing is used as a sealing material. Since this rubber packing has no durability unless it is cooled, it is necessary to cool the periphery of the rubber. However, since the material of the reaction tube that becomes high temperature is quartz or SiC (silicon carbide), the reaction tube itself must be cooled. I can't. For this reason, the housing (generally made of metal) where the rubber packing is pressed against the reaction tube is water-cooled, but the part in contact with the reaction tube becomes hot due to poor heat conduction in the rubber packing, and the rubber packing deteriorates. There is a problem that a leak occurs or the amount of gas released from the rubber itself increases, which adversely affects the quality of the thin film on the wafer.

(Specific purpose of the invention) As described above, by reducing the deterioration of the rubber packing, which is not preferable for forming the thin film, it is possible to expect improvement of the quality of the thin film and improvement of the life of the device.

(Structure and operation of device) The drawing is a sectional view showing an example of the structure of a low pressure CVD apparatus embodying the present invention. Referring to the symbols in the figure, 1 is a transparent quartz reaction tube, 2 to 5 are rubber packing housings, 6
Is a heater for heating, 7 is a rubber packing, 8 and 9 are radiant heat shields made of metal embedded in 3 and 5, respectively, 10 is a thin film forming gas inlet, 11 and 12 are coupling screws, and 13 to Reference numeral 16 is a water cooling cavity, and 17 is a connection port to a decompression pump (exhaust pump). As an example of dimensions, the inner diameter of the reaction tube 1 is 150 to 200 mm.
φ, the length L ₂ of the heater 6 is 1800 mm, the reaction tube length L ₁ is 2000
It is about mm. It should be noted that 2 to 5, 7, 8 and 9 are naturally ring-shaped.

In the low pressure CVD apparatus, the inside of the reaction tube 1 is depressurized, a silicon wafer is put into the reaction tube, and the rubber packing housing 2 to
5 and the rubber packing 7 are used to make both ends of the reaction tube airtight, and the housing 3 side 17 is evacuated by a decompression pump, and a thin film forming gas (process gas) is introduced into the reaction tube from the gas introduction port 10 on the housing 5 side. It is a device for forming various thin films on the wafer by flowing into the substrate.

To explain in more detail with reference to the drawings, radiant heat shields 8 and 9 are provided inside the reaction tube 1 in contact with the rubber packing 7 at both ends of the reaction tube 1, and these ring-shaped heat shields 8 and 9 are provided. The inside of each is made hollow, and each is connected to the hollow portions of the ring-shaped rubber packing housings 3 and 5 as shown. A cavity is also provided inside the rubber packing housing 2. Cooling water is circulated and discharged through cooling water supply ports and discharge ports (not shown) in all of these cavities for cooling, but the rubber packing 7 that is in direct contact with the reaction tube is a rubber packing housing. Not only is it cooled by 2 to 5, but also the radiation heat from the heater 6 is blocked by the radiation heat shields 8 and 9 made of metal, so that deterioration due to heat is significantly reduced. The ring-shaped rubber packing housings 3 and 5 also serve as a lid of the reaction tube 1.

Next, the heating of the rubber packing will be further described. The rubber packing is made of heat resistant rubber such as silicone rubber or fluororubber, and the heat resistant temperature of these is 200 to 250 ° C. Although the ratio of direct heating by heat conduction from the reaction tube 1 to radiant heating is not quantitatively known, the surface temperature of the reaction tube seal part is about 250 ° C by thermocouple measurement in the structure that does not block radiation. is there. For this reason, at present, the O-ring is replaced every time the reaction tube is cleaned, but it is expected that the implementation of the present invention lowers the surface temperature of the reaction tube sealing portion and significantly extends the replacement period of the rubber packing.

(Effect of the Invention) Since the deterioration of the rubber packing is reduced by the implementation of the present invention, the amount of gas leaked from the leak and the rubber itself is reduced,
Since the contamination inside the reaction tube is reduced, the quality of various thin films formed on the wafer is improved, and the effect of improving the performance of the semiconductor device and the life of the manufacturing apparatus can be obtained.

[Brief description of drawings]

The drawing is a cross-sectional view showing a configuration example of a low pressure CVD apparatus embodying the present invention. 1 ... Reaction tube, 2-5 ... Rubber packing housing, 6 ... Heater, 7 ... Rubber packing, 8, 9 ... Radiant heat blocking part, 10 ... Gas inlet, 11, 12 ... Screw, 13 to 16 …… Cavity for water cooling, 17 …… Connection port to pressure reducing pump.

Claims (1)

[Scope of utility model registration request] 1. A cooling device for a ring-shaped rubber packing, which is used for airtight seal portions at both ends of a reaction tube which is heated from the outside and reduced in pressure, and which is in contact with the ring-shaped rubber packing. Inside the reaction tube, which is close to the inner wall of the reaction tube, has a metal radiant heat blocking ring having a water cooling cavity for water cooling inside, and the above ring-shaped rubber packing is pressed against the outer wall of the reaction tube and the inside of the reaction tube is water cooled. A ring-shaped first rubber packing housing having a water cavity, and a water-cooling water-flowing cavity which is integrated with the radiant heat blocking ring and is connected to the cavity. A reaction comprising a second outermost rubber packing housing which is not in contact with a reaction tube provided with a communication port to the pressure reducing pump or a process gas inlet port, respectively. End of the hermetically sealed portion cooling device.