JPH02143526A - Deposited film formation furnace of semiconductor device - Google Patents

Abstract

PURPOSE:To prevent any particle production from occurring due to cooled down deposited gas by a method wherein protrusions approaching to the inner periphery of manifolds and furnace tube end as well as a depositing gas guide holes communicating with the inside and the outside of the furnace tube are provided on caps. CONSTITUTION:A front manifold 2a is junctioned with a front flange 1a provided on the front end of a furnace tube 1 in a horizontal pressure reduced CVD furnace while the junction part is sealed with O-rings 3. Then, the front end opening of the manifold 2a is opened and closed by a front cap 8a on whose central part a protrusion 9a to be inserted into the manifold 2a is formed. In such a constitution, wafers are contained in the furnace tube 1 while depositing gas is fed from guide holes 10a to the furnace tube 1 to heat the wafers for forming deposited films on the wafers. At this time, the manifold 2a is fed with nitrogen gas from an inert gas feeding hole 6 so fill up the gap between the cap 8a, the manifold 2a and the furnace tube 1 with the nitrogen gas. Within the rear manifold 2b, similar procedures are followed. Consequently, the depositing gas can be prevented from permeating into the part near the O-ring 8 to prevent any product from sticking on the manifolds 2a, 2b.

Description

[Detailed Description of the Invention] [Summary] Regarding a furnace for forming a grown film on a wafer in the manufacturing process of semiconductor devices, the purpose of this invention is to prevent the generation of particles due to cooling of the growth gas, and to prevent the generation of particles at the end of the furnace tube. Annular manifolds are arranged in series, and an O-ring is interposed between the joint surface of the furnace tube and the manifold to seal the manifold, a water channel is provided near the O-ring of the manifold to circulate cooling water, and the opening of the manifold is closed with a cap. In a growth film forming furnace that heats a furnace tube by closing it, the cap is provided with a protrusion close to the inner peripheral surface of the manifold and the end of the furnace tube, and also has a growth gas guide hole that communicates between the inside and outside of the furnace tube and guides the growth gas. The manifold is provided with an inert gas supply hole for supplying inert gas to the gap between the manifold, the cap, and the end of the furnace tube.

[Industrial Field of Application] This invention relates to a furnace for forming a grown film on a wafer in the process of manufacturing semiconductor devices.

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

[Prior Art] Conventionally, in a low-pressure CVD furnace, which is a type of growth film forming furnace, as shown in FIG. 4, an annular front manifold 22 is provided at the front end of a furnace tube 21 formed integrally with quartz. A rear manifold 23 is also provided at the rear end. Growth gas is supplied into the furnace tube 21 from a gas supply pipe 24 connected to the front manifold 22, and a suction pump (not shown) is connected to an exhaust pipe 25 connected to the rear manifold 23. The pressure inside the furnace tube 21 is reduced and waste gas can be discharged outside the furnace tube 21. The opening of the front manifold 22 can be opened and closed by a cap 26 moved by an opening/closing device (not shown), and when the cap 26 is closed with the wafer accommodated in the furnace tube 21, the gas is grown from the gas supply tube 24. When the furnace tube 21 is heated by the heating device 27 while supplying gas, a grown film is formed on the wafer inside the furnace tube 21.

In the above-described low-pressure CVD furnace, as shown in FIG. 5, an O-ring 28 is interposed between the front manifold 22, the furnace tube 21, and the cap 26 to maintain airtightness. Two water channels are formed around the O-ring 28 of the front manifold 22, and cooling water 30 circulates in the water channels 29.
This cools the O-ring 28, thereby preventing damage to the O-ring 28 due to the high heat transmitted from the furnace tube 21.

[Problems to be Solved by the Invention] However, in the above-described low-pressure CVD furnace, the vicinity of water #129 on the inner peripheral surface of the front manifold 22 is cooled by the cooling water 30 that is circulated into the water channel 29 of the front manifold 22. The growth gas supplied from the gas supply pipe 24 into the front manifold 22 is cooled, and powdered products adhere to the inner circumferential surface near the water channel 29.

For example, in a CVD furnace for growing a Si3N4 film, white powder of NH4C1 adheres to the inner peripheral surface of the front manifold 22 as a product. Then, there is a problem that the products scatter into the furnace tube 21 and become particles.

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 with such a configuration, products do not adhere to the inner peripheral surface of the manifold.
The above problem does not occur. However, providing a gas supply hole in the furnace tube not only increases the manufacturing cost of the furnace tube, but also reduces the strength of the furnace tube, making it more likely to crack. A connecting member made of Teflon or the like is used, but since it is located near the furnace tube, it is exposed to high heat and deforms, making 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 tube, and as a result, it is necessary to increase the transport stroke of the wafer transport device that carries wafers into and out of the furnace tube. There is also the problem that the entire device becomes larger.

An object of the present invention is to provide a grown film forming furnace that can prevent the generation of particles due to cooling of the growth gas without adopting a structure in which a growth gas supply hole is provided in the furnace tube.

[Means for Solving the Problems] FIG. 1 is a diagram illustrating the principle of the present invention. That is, furnace tube 1
An 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 a water channel 4 for circulating cooling water 5 is provided near the O-ring 3 of the manifold 2. The furnace tube 1 is heated by closing the opening of the manifold 2 with a cap 8. The cap 8 is provided with a protrusion 9 that is close to the inner peripheral surface of the manifold 2 and the end of the furnace tube 1, and is also provided with a growth gas guide hole 10 that communicates between the inside and outside of the furnace tube 1 and guides the growth gas. 2 has an inert gas supply hole 6 for supplying inert gas into the gap between the manifold 2, the cap 8, and the end of the furnace tube 1.
is provided.

[Function] The growth gas is passed 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 inward and outward and cooled by the cooling water 5, is filled with inert gas to prevent the growth gas from entering.

[Embodiment 2] A first embodiment in which the present invention is embodied in a horizontal reduced pressure CVD furnace will be described below with reference to FIG. 2. A front flange 1a is provided at the front end of the furnace tube 1; 1a
A front manifold 2a is joined to the front manifold 2a. The joint portion 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 within the water channel 4. Also,
The inner diameter of the front manifold 2a is formed to be slightly larger than the inner diameter of the furnace tube 1.

A large number of inert gas supply holes 6 are formed around the entire circumference of the front manifold 2a, communicating the inside and outside of the front manifold 2a, and an inert gas such as nitrogen gas is supplied from the outside through a supply pipe 7.
Supplied at a flow rate of scc+.

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 and 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 opening of the front manifold 2a is closed with this front cap 8a, the protrusion 9a
The tip 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 surface of the front manifold 2a via the O-ring 3 cooled with cooling water 5 in the same manner as described above.

Two growth gas supply holes 10 are formed in the front cap 8a and pass through the protrusion 9a.
A supply pipe 11 is connected to.

Then, with the opening of the front manifold 2a closed by the front cap 8a, the supply pipe 11 and the growth gas guide hole 10 are closed.
Growth gas is supplied into the furnace tube 1 through a.

A rear manifold 2b is attached to the rear flange 1b at the rear end of the furnace tube 1.
are joined via an O-ring 3, and the O-ring 3 has the same structure as the front manifold 2a and is cooled by cooling water 5. An exhaust pipe 12 is connected to the rear end surface of the rear manifold 2b, and a pump (not shown) connected to the exhaust pipe 12 reduces the pressure inside the furnace tube 1.
The waste gas inside is now vented.

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

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

Now, in the reduced pressure CVD furnace configured as described above, the front cap 8a is closed with the wafer housed in the furnace tube 1, and when heating is performed while supplying growth gas into the furnace tube 1 from the growth gas guide hole 10a, A grown film is formed on the wafer. At this time, nitrogen gas is supplied from the inert gas supply hole 6 to the front manifold 2a, and the nitrogen gas flows into the reduced pressure furnace tube 1. As a result, the front cap 8a, the front manifold 2a, and the furnace tube Since the gap between the O ring 1 and the O ring 3 is always filled with nitrogen gas, the growth gas never enters this gap. Therefore, the growth gas is not cooled by the cooling water 5 near the O ring 3, and the Since it is possible to prevent the products from adhering to the inner peripheral surface of the part manifold 2a, it is possible to prevent the generation of particles due to the scattering of the products.

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

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

[Effects of the Invention] As detailed above, the present invention provides a grown film forming furnace that can prevent the generation of particles due to cooling of the growth gas without adopting a configuration in which a growth gas supply hole is provided in the furnace tube. It can exhibit excellent effects.

[Brief explanation of the drawing]

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

Claims (1)

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