JPH03219200A - Exhaust device - Google Patents

Abstract

PURPOSE:To enable uniform exhaust and reduce the dispersion of characteristics in a wafer by providing the exhaust pipe of an exhaust device with a branch pipe, and constituting the branch pipe so as to open at the predetermine pressure of the exhaust. CONSTITUTION:A process gas is made to flow through one tube 10 among a plurality of process tubes 10, and no process gas is made to flow through other tubes 10, with a lid body 14 closed. In this state, the flowrate of the process gas flowing for the exhaust capacity of an exhaust fan 20, is small and, therefore, the inside of an exhaust tube 22 falls in a substantially negative pressure condition. As a result, the differential pressure acting on a movable valve 42 becomes larger than the weight thereof, and the valve 42 comes to be substantially afloat. Consequently, the atmosphere enters the exhaust tube 22 via a recessed part and pressure in the exhaust tube 22 is always maintained at the predetermined level. Desired pressure can be obtained via the change of the weight of the valve 42 per unit area.

Description

[Detailed description of the invention] [Purpose of the invention] (Industrial application field) The present invention relates to an exhaust system.

(Conventional technology) The pressure and flow rate inside the exhaust pipe are detected, and the
Japanese Unexamined Patent Publications No. 62-63421 and No. 6 disclose a method for uniformly exhausting the inside of the device by adjusting a flow rate control valve provided in the exhaust pipe.
There are No. 3-238281 and Japanese Unexamined Patent Publication No. 63-304620.

Furthermore, there is a method disclosed in Japanese Patent Application Laid-open No. 124226/1983 that makes the exhaust gas pressure from the device constant to the pressure at the height of the liquid column.

(Problem to be Solved by the Invention) The technology in the former document requires a complicated and expensive device configuration, and requires frequent maintenance in devices where products adhere to the exhaust system. There are points for improvement such as:

The latter technique has an improvement in that exhaust gas is not discharged through the liquid column provided in the exhaust system unless the inside of the device becomes positive pressure, and the flow of gas in the device is not uniform.

(Objective of the Invention) The present invention has been made in view of the above points, and an object of the present invention is to provide an exhaust device which has a simple configuration and which enables uniform exhaust gas, thereby causing no turbulence in the gas flow within the device.

(Summary of the Invention) The present invention provides an exhaust system having a mechanism for exhausting air through an exhaust pipe, in which a branch pipe is provided in the exhaust pipe, and the branch pipe is opened when the inside of the exhaust pipe is at a predetermined pressure state. It is composed of

(Function) This invention connects a tributary pipe to the exhaust pipe, and sets the structure of this tributary pipe so that when the inside of the exhaust pipe becomes less than a predetermined negative pressure, atmospheric air flows in. It is designed to automatically obtain a negative pressure state.

(Example) Hereinafter, an example in which the apparatus of the present invention is applied to a vertical heat treatment furnace will be specifically described with reference to the drawings.

The vertical process tube 10 is made of a heat-resistant material such as a quartz tube, and has one end connected to a process gas introduction pipe 12 and the other end connected to an exhaust pipe 22.

A cylindrical heater 16 is provided around the process tube 10,
For example, a resistance heating type heater is provided, and the process tube IO is heated to a predetermined heat treatment temperature, for example, 800 to 1200°C.
It can be set as appropriate within the range of .

A large number of wafers 18 are carried into the process tube 10 as objects to be processed, and these wafers are stored in an iF1 thermal wafer boat 17 made of, for example, quartz.

This boat 17 is placed on a mounting table 19 and housed in a predetermined position within the process tube 10.

The mounting table 19 is installed on the lid 14, and the lid 14 can be moved up and down by a lifting mechanism (not shown).
It is configured to carry out 8 loading/unloading operations.

Processing gas is supplied to the introduction pipe 12 via a mass flow controller 30.

In this embodiment, the exhaust of a plurality of process tubes 10 is driven by one exhaust fan 20 having a large exhaust capacity and disposed in a common exhaust pipe 23. This exhaust fan 20
A vacuum pump may also be used.

A characteristic feature of this embodiment is that a branch pipe 40 is disposed in the middle of each exhaust pipe 22 corresponding to a plurality of process tubes 10. Details of this tributary pipe 40 will be explained with reference to FIG. 2.

That is, an enormous recess 46 is provided at the end of the pipe 48 bent downward from the middle of the exhaust pipe 22, and the recess 4
An O-ring 44 made of an elastic member is disposed on the inner edge of 6.

Above the O-ring 44, a circular movable valve 42 with a concave center presses against the O-ring 44 with its own weight, establishing an airtight state comparable to that of a tributary pipe.

Next, the operation of the apparatus of the embodiment will be explained. One process tube 10 among the plurality of process tubes 10
Processing gas is flowing through the other process tube 10.
When the processing gas does not flow through the exhaust pipe z2 and the lid body 14 is closed, the flow rate of the processing gas flowing through the exhaust pipe z2 is small relative to the exhaust capacity of the exhaust fan 2o, so the pressure inside the exhaust pipe z2 becomes a large negative pressure state. Become.

As a result, the force of the differential pressure applied to the movable valve 42 becomes greater than the weight of the movable valve 42, and the movable valve 42 rises significantly and the recess 4
6, the atmosphere flows into the exhaust pipe 22, and the pressure inside the exhaust pipe 22 is always maintained at a predetermined pressure.

The desired pressure can be obtained by changing the weight per unit area of the movable valve 42, for example, the differential pressure with the atmosphere - ], Omm
If H20 is the desired pressure, 1 atm = I0000w
Based on the relationship aH201kg/c2If, the weight of the movable valve 42 should be 1 g/ci. The weight of the movable valve 42 can be adjusted by changing the material or thickness of the movable valve 42. When wafer oxidation or diffusion processing is performed, the differential pressure between the atmosphere and the inside of the exhaust pipe 22 where the wafer processing uniformity is good is -1 to -20 m+nH,
It was in the range of 0. Therefore, the pressure within the exhaust pipe 22 that is desirable for uniform exhaustion is within the above pressure range.

Next, when the lid 14 is opened in order to carry a wafer into another process tube 10, a large amount of air flows from the process tube 10 into the exhaust pipe 22, and the pressure inside the exhaust pipe 22 increases. At this time, tributary pipe 4, which had been wide open until now,
The opening degree of the movable valve 42 at 0 is narrowed and the desired pressure is stabilized. In this way, the opening degree of the movable valve 42 of the tributary pipe 40 changes depending on the pressure within the exhaust pipe 22, and operates so that a desired pressure is always maintained. Even when the flow rate of gas flowing through the process tube 10 is changed to change the process state, the movable valve 42 of the branch pipe 40 is operated in the same manner as described above, and the desired pressure is always maintained.

Therefore, it is possible to uniformly exhaust the process gas flowing through the process tube 10, thereby eliminating disturbances in the gas flow within the apparatus, and making it possible to process wafers with good surface-to-inner surface uniformity.

Note that the present invention is not limited to the above-mentioned embodiments, and various modifications can be made within the scope of the gist of the present invention.

The present invention is not necessarily applied to a case in which a common exhaust drive source is used for a plurality of process tubes 10, and even when the exhaust pipe 22 is provided exclusively for a single process tube 10, it can be applied to a process tube 10. The flow rate of the processing gas may be changed to change the state, or the performance of the exhaust fan 20 may change due to fluctuations in the power supply voltage, etc., so the present invention is useful for uniform exhaustion.

The automatically controlled exhaust system shown in the above literature generally has an improvement point in that it is difficult to adjust over a wide pressure range, but by using it in combination with the present invention, a significant improvement can be achieved. can.

Either the weight of the movable valve 42 can be adjusted so that the movable valve 42 of the tributary pipe 40 opens and closes at a desired pressure, or the movable valve 4
Pushing or pulling 2 with a spring is also useful in practicing the invention.

When the present invention is used in equipment such as oxidation furnaces and diffusion furnaces where corrosive gases such as HCff flow at high temperatures, the parts of the exhaust pipe 22 and branch pipes 40 that come into contact with the process gas are made of non-metallic material such as fluororesin. configurations are also useful in implementing the invention.

In addition, in order to finely adjust the pressure to the desired level, a valve is connected to the tributary pipe 40.
It is also useful to attach it to the exhaust pipe 22 between the flow pipe 40 and the process tube 10, or between the branch pipe 40 and the common exhaust pipe 23.

Furthermore, the present invention is not limited to heat treatment furnaces such as oxidation furnaces and diffusion furnaces.
It goes without saying that the invention may be applied to atmospheric pressure CVD equipment, spin quarter equipment, and other atmospheric pressure processing equipment.

It goes without saying that the present invention can be applied not only to vertical devices but also to horizontal devices such as horizontal heat treatment furnaces.

〔Effect of the invention〕

As explained above, according to the present invention, uniform exhaust gas can be achieved by always keeping the exhaust pressure of the exhaust pipe constant with a simple configuration, and variations in characteristics in rewafers can be reduced, which is a remarkable effect.

[Brief explanation of drawings]

FIG. 1 is an explanatory view of an embodiment in which the present invention is applied to a vertical heat treatment apparatus, and FIG. 2 is a schematic explanatory view showing an enlarged view of a tributary pipe provided in the middle of the exhaust pipe in FIG. 10... Process tube 12, gas introduction pipe 14, lid 16, heater 17, boat 18, wafer 19, mounting table 20, exhaust fan 22, exhaust pipe 23, common exhaust pipe 30, mass flow・Controller 40・・tributary pipe 42・・movable valve 44・・O ring 46 recess 48・piping Fig. 2

Claims (1)

[Claims] An exhaust device having a mechanism for exhausting air through an exhaust pipe, characterized in that the exhaust pipe is provided with a branch pipe, and the branch pipe is configured to open when the inside of the exhaust pipe is in a predetermined pressure state. Device.