JP2674811B2 - Growth film forming furnace for semiconductor devices - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Outline] A furnace for forming a growth film on a wafer in the process of manufacturing a semiconductor device, which aims to prevent generation of particles due to cooling of a growth gas, is provided at an end portion of a furnace tube. A series of annular manifolds are connected and the joint surface between the furnace tube and the manifold is sealed with an O-ring interposed. A water passage for returning cooling water is provided near the O-ring of the manifold, and the opening of the manifold is capped. In a growth film forming furnace in which a furnace tube is heated with a lid, a cap is provided with a protrusion near the inner peripheral surface of the manifold and an end of the furnace tube, and a growth gas guide hole for communicating the inside and outside of the furnace tube and guiding a growth gas. The manifold is provided with an inert gas supply hole for supplying an inert gas in the gap between the manifold, the cap and the end of the furnace tube.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a furnace for forming a growth film on a wafer in a semiconductor device manufacturing process.

In the growth film forming furnace, the furnace tube containing the growth gas and the wafer is heated to form the growth film on the wafer, but in order to improve the yield of the wafer, generation of particles in the wafer atmosphere is prevented. There is a need to.

[Prior Art] In a conventional low pressure CVD furnace, which is one type of growth film forming furnace, an annular front manifold 22 is provided at the front end of a furnace tube 21 integrally formed of quartz as shown in FIG. A rear manifold 23 is also provided at the rear end. Then, the growth gas is supplied into the furnace pipe 21 from a gas supply pipe 24 connected to the front manifold 22, and an intake pump (not shown) is connected to an exhaust pipe 25 connected to the rear manifold 23. The inside of the furnace tube 21 is decompressed, and waste gas can be discharged to the outside of the furnace tube 21. The opening of the front manifold 22 can be opened / closed by a cap 26 moved by an opening / closing device (not shown). The cap 26 is closed while the wafer is housed in the furnace tube 21, and the gas is supplied from the gas supply tube 24. When the furnace tube 21 is heated by the heating device 27 while supplying gas, a growth film is formed on the wafer in the furnace tube 21.

In the above-described low pressure CVD furnace, as shown in FIG. 5, an O-ring 28 is interposed at the joint surface between the front manifold 22, the furnace tube 21 and the cap 26 to maintain airtightness. A water channel 29 is formed around the O-ring 28 of the front manifold 22, and the O-ring 28 is formed by the cooling water 30 circulating in the water channel 29.
O-ring 28 due to the high heat transmitted from the furnace tube 21
To prevent damage.

[Problems to be Solved by the Invention] However, in the decompression CVD furnace as described above, the vicinity of the water passage 29 on the inner peripheral surface of the front manifold 22 is cooled by the cooling water 30 which is returned to the water passage 29 of the front manifold 22. The growth gas supplied from the gas supply pipe 24 into the front manifold 22 is cooled, and a powdery product adheres to the inner peripheral surface of the water channel 29 in the vicinity thereof. For example, in a CVD furnace for growing a film of Si3N4, NH4Cl white powder adheres to the inner surface of the front manifold 22 as a product. Then, there is a problem that the product is scattered into the furnace tube 21 and becomes a particle.

On the other hand, a low pressure CVD furnace has been proposed in which a gas supply hole is provided in the furnace tube to supply growth gas, and in such a structure, the product does not adhere to the inner peripheral surface of the manifold.
The above problems do not occur. However, providing the gas supply hole in the furnace tube increases the manufacturing cost of the furnace tube, reduces the strength of the furnace tube, and is likely to cause cracks, and the connecting portion between the gas supply hole and the gas supply tube is A connecting member formed of Teflon or the like is used, but it is located near the furnace tube and is exposed to high heat to change it, which makes it difficult to ensure airtightness. Furthermore, in order to prevent interference between the gas supply pipe and the heating device, it is necessary to lengthen the furnace pipe, and as a result, it is necessary to increase the transfer stroke of the wafer transfer device for loading and unloading the wafer into the furnace pipe, There is also a problem that the entire device becomes large.

An object of the present invention is to provide a growth film forming furnace capable of preventing the generation of particles due to cooling of the growth gas without adopting the structure of providing the growth gas supply hole in the furnace tube.

[Means for Solving the Problems] FIG. 1 is an explanatory view of the principle of the present invention. That is, the annular manifold 2 is connected to the end of the furnace tube 1, and the joint surface between the furnace tube 1 and the manifold 2 is sealed with an O-ring 3, and the cooling water 5 is provided in the vicinity of the O-ring 3 of the manifold 2. A water channel 4 for reflux is provided, and the opening of the manifold 2 is closed with a cap 8 to heat the furnace tube 1. The cap 8 is provided with a protrusion 9 close to the inner peripheral surface of the manifold 2 and the end of the furnace tube 1, and a growth gas guide hole 10 for communicating the inside and outside of the furnace tube 1 to guide the growth gas. Indicated at 2 is an inert gas supply hole 6 for supplying an inert gas into the gap between the manifold 2, the cap 8 and the end of the furnace tube 1.
Is provided.

[Operation] The growth gas flows from the growth gas guide hole 10 of the cap 8 to the furnace tube 1
The vicinity of the inner peripheral surface of the manifold 2 which is guided inside and outside and cooled by the cooling water 5 is filled with an inert gas, and the invasion of the growth gas is blocked.

[Embodiment] The first embodiment in which the present invention is embodied in a horizontal decompression CVD furnace will be described below with reference to FIG. 2. A front flange 1a is provided at the front end of a furnace tube 1, and the front flange 1a is provided. A front manifold 2a is joined to 1a. The joint is sealed with an O-ring 3, and a water channel 4 is formed in the front manifold 2 so as to cover the O-ring 3, and cooling water 5 is circulated in the water channel 4. The inner diameter of the front manifold 2a is slightly larger than the inner diameter of the furnace tube 1.

A large number of inert gas supply holes 6 communicating between the inside and the outside of the front manifold 2a are formed along the entire circumference thereof, and an inert gas, for example, nitrogen gas is supplied from the outside through a supply pipe 7 to about 10 SCCM.
Is supplied at a flow rate of.

The front end opening of the front manifold 2a is opened and closed by a front cap 8a made of quartz, and the front cap 8a is opened and closed by an opening / closing device (not shown). That is, a protrusion 9a that can be inserted into the front manifold 2a is formed in the center of the front cap 8a, and when the front cap 2a closes the opening of the front manifold 2a, the tip of the protrusion 9a is formed. Is close to the front end of the furnace tube 1, and the periphery of the front cap 8a is joined to the front end of the front manifold 2a via the O-ring 3 cooled by the cooling water 5 as described above.

Two growth gas supply holes 10 are formed in the front cap 8a so as to penetrate the protrusions 9a, and a supply pipe 11 is connected to the growth gas supply holes 10. Then, the growth gas is supplied into the furnace tube 1 through the supply pipe 11 and the growth gas guide hole 10a in a state where the front manifold 2a opening is closed by the front cap 8a.

A rear manifold 2b is joined to a rear flange 1b of the rear end of the furnace tube 1 through an O-ring 3, and the O-ring 3 is cooled by cooling water 5 in the same configuration as the front manifold 2a. The exhaust pipe is attached to the rear end face of the rear manifold 2b.
The inside of the furnace pipe 1 is decompressed by a pump (not shown) connected to the exhaust pipe 12, and the waste gas inside the furnace pipe 1 is discharged.

A tubular rear cap 8b is disposed in the rear manifold 2b, and a tip portion of the rear cap 8b projects into the exhaust pipe 12 to form a growth gas guide hole 10b, and a gap between the exhaust pipe 12 and an inner peripheral surface thereof. Is sealed with an O-ring 3. Further, a projection 9b is formed at the base end of the rear cap 8b to form a slight gap between the rear manifold 2b and the rear end of the furnace tube 1.

An inert gas supply hole 6 is formed in the rear manifold 2b so as to communicate the inside and outside thereof, and nitrogen gas is supplied from the outside through a supply pipe 7 similarly to the front manifold 2a.

Now, in the low pressure CVD furnace configured as described above, when the front cap 8a is closed in the state where the wafer is accommodated in the furnace tube 1 and heating is performed while supplying the growth gas into the furnace tube 1 from the growth gas guide hole 10a, A growth film is formed on the wafer. At this time,
In the front manifold 2a, nitrogen gas is supplied from the inert gas supply hole 6, and the nitrogen gas flows into the depressurized furnace tube 1. As a result, the gap between the front cap 8a, the front manifold 2a and the furnace tube 1 is always filled with nitrogen gas, so that the growth gas does not enter this gap. Therefore, the growth gas is not cooled by the cooling water 5 in the vicinity of the O-ring 3, and it is possible to prevent the product from adhering to the inner peripheral surface of the front manifold 2a. Occurrence can be prevented in advance.

On the other hand, in the rear manifold 2b as well, the nitrogen gas similarly supplied from the inert gas supply hole 6 passes through the gap between the rear manifold 2b, the rear cap 8b and the rear end of the furnace tube 1 and the rear cap.
Since it is discharged from the inside of 8b to the exhaust pipe 12, the growth gas is prevented from entering the vicinity of the O-ring 3, and as a result, the rear manifold is
Product adhesion to 2b is prevented.

FIG. 3 shows a second embodiment in which the present invention is embodied in a vertical furnace. Also in this embodiment, a lower manifold 2c and a lower cap 8c having the same structure as the front manifold 2a of the above embodiment are provided at the opening of the furnace tube 13, and the nitrogen gas supplied from the inert gas supply hole 6 causes It is possible to prevent the growth gas from entering the vicinity of the ring 3 and prevent the generation of products.

[Effects of the Invention] As described in detail above, the present invention provides a growth film forming furnace capable of preventing the generation of particles due to cooling of the growth gas without adopting the structure of providing the growth gas supply hole in the furnace tube. Can exert an excellent effect.

[Brief description of the drawings]

FIG. 1 is a diagram for explaining the principle of the present invention, FIG. 2 is a vertical sectional view showing an embodiment in which the invention is embodied in a horizontal furnace, and FIG. 3 is an embodiment in which the invention is embodied in a vertical furnace. Longitudinal section, 4th
FIG. 5 is a front view showing a conventional furnace, and FIG. 5 is a sectional view of a front manifold portion of the conventional furnace. In the figure, 1 is a furnace tube, 2 is a manifold, 3 is an O-ring, 4 is a water channel, 5 is cooling water, 6 is an inert gas supply hole, 8 is a cap, 9 is a protrusion, and 10 is a growth gas guide hole. is there.

Claims (1)

(57) [Claims] 1. An annular manifold (2) is connected to an end of a furnace tube (1), and an O-ring (3) is interposed between the furnace tube (1) and the manifold (2) to seal the joint. In the vicinity of the O-ring (3) of the manifold (2), a water channel (4) for circulating cooling water (5) is provided, and an opening of the manifold (2) is closed with a cap (8) to form a furnace tube (1). ), A cap (8) is provided with a protrusion (9) close to the inner peripheral surface of the manifold (2) and the end of the furnace tube (1) and communicates the inside and outside of the furnace tube (1). And a growth gas guide hole (10) for guiding the growth gas is provided, and an inert gas is supplied to the manifold (2) in the gap between the manifold (2) and the cap (8) and the end of the furnace tube (1). A growth film forming furnace for a semiconductor device, characterized in that an inert gas supply hole (6) is provided.