JPH04280625A - Gas control device for load lock chamber of vertical type difusion cvd device - Google Patents

Abstract

PURPOSE:To reduce the quantity of nitrogen gas used by a method wherein the atmospheric gas in a load lock chamber is circulated by opening an ON-OFF valve when oxygen concentration exceeds the prescribed value and the ON-OFF valve is closed when the oxygen concentration is lower than the prescribed value. CONSTITUTION:ON-OFF valves 8 and 9 are opened, nitrogen gas is allowed to flow, and the interior of a load lock chamber 2 is replaced with nitrogen gas. When the set valve of the oxygen concentration in the load lock chamber 2 becomes 1ppm or lower, for example, in the above-mentioned replacement process, the ON-OFF valves 8 and 9 are closed, the sealed-in nitrogen gas is circulated to bypass pipe 10 by driving a circulation pump 11. Besides, the opening and closing of the ON-OFF valves 8 and 9 is controlled in such a manner that the pressure in the load lock chamber 2 will be a little higher than the atmospheric pressure taking into consideration of the leak from the load lock chamber 2 and the ON-OFF valves 8 and 9. As a result, the quantity of nitrogen gas consumed can be reduced.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in gas control in a load lock chamber provided in a vertical diffusion CVD apparatus, which is one type of semiconductor manufacturing apparatus.

0002

[Prior Art] A vertical diffusion CVD apparatus has an airtight reaction chamber made of a vertically installed quartz tube, a heater surrounding the reaction chamber, and a heater connected below the reaction chamber. An airtight load lock chamber provided, a wafer loading mechanism, a wafer transfer mechanism provided inside the load lock chamber,
It is composed of a boat or the like that is placed on the wafer loading mechanism and wafers are loaded in multiple stages.

[0003] Wafer processing is carried out by loading the wafers carried into the load lock chamber into the boat by the wafer transfer mechanism, loading the boat into the reaction chamber by the wafer loading mechanism, and placing the wafer in a high temperature reaction gas atmosphere. When the wafers are processed, the wafer loading mechanism pulls out the boat into the load lock chamber, and the wafer transfer mechanism takes out the wafers from the boat.

[0004] In the series of wafer processing described above, the load lock chamber must be kept clean with nitrogen gas (atmosphere gas) in order to prevent oxidation of the wafers or to prevent contamination by particles.

A conventional gas control method for a load lock chamber is shown in FIG.

A nitrogen gas supply pipe 3 and an exhaust pipe 4 are connected to a load lock chamber 2 provided below the reaction chamber 1, and vacuum on-off valves 5 and 6 are provided in the gas supply pipe 3 and exhaust pipe 4. The exhaust pipe 4 is also provided with a vacuum pump 7. In this conventional device, the load lock chamber 2 is evacuated by the vacuum pump 7 with the vacuum shut-off valve 5 closed, and then filled with nitrogen gas to bring it to atmospheric pressure in a nitrogen gas atmosphere. After filling with nitrogen gas, seal the load lock chamber.

In addition, in the device shown in FIG. 3, the load lock chamber 2 is not evacuated, but nitrogen gas is continued to flow from the beginning, and the nitrogen gas is replaced with nitrogen gas, and the nitrogen gas is continued to flow even after the replacement to maintain cleanliness. .

[0008]

However, in the conventional device shown in FIG. 2, atmospheric pressure is applied to the load-lock chamber when the load-lock chamber is evacuated, so the load-lock chamber must be made sturdy and has a large weight. As the size increases, the production cost also increases.

Furthermore, the conventional device shown in FIG. 3 has the advantage of being able to reduce the weight of the load-lock chamber and of immediately exhausting particles generated in the load-lock chamber. This required high running costs. In view of the above circumstances, the present invention aims to reduce the weight of the load lock chamber and to significantly reduce the amount of nitrogen gas used.

0010

[Means for Solving the Problems] The present invention connects an atmospheric gas supply pipe and an exhaust pipe to a load lock chamber connected to a lower part of a reaction chamber, and provides an on-off valve in the supply pipe and the exhaust pipe, A bypass pipe having a circulation pump and a filter connects the on-off valve downstream of the supply pipe and the on-off valve upstream of the exhaust pipe, and an oxygen concentration detector for detecting oxygen concentration is provided in the load lock chamber, and the oxygen concentration is detected. The device is characterized in that it is configured to open and close the on-off valve and drive the circulation pump based on the detection results of the meter.

[0011]

[Function] When the oxygen concentration is above a predetermined value, both on-off valves are opened to allow atmospheric gas to flow through. When the oxygen concentration is below a predetermined value, both on-off valves are closed and the circulation pump is driven to create an atmosphere in the load lock chamber. Circulate the gas.

0012

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

Components in FIGS. 1 and 2 that are the same as those shown in FIG.

An on-off valve 8 is provided in the supply pipe 3, and an on-off valve 9 is provided in the exhaust pipe 4.
is provided, and the supply pipe 3 and the exhaust pipe 9 are connected to a bypass pipe 1.
Connect with 0. The bypass pipe 10 is connected to the downstream side of the on-off valve 8 and the upstream side of the on-off valve 9. Further, the bypass pipe 10 is provided with a circulation pump 11 and a filter 12, and the load lock chamber 2 is provided with an oxygen concentration detector 13 and a pressure gauge 14. The oxygen concentration detector 13, pressure gauge 1
The detection results of step 4 are input to a control device 15, and the control device 15 operates the on-off valves 8 and 9 and the circulation pump 11 based on the detection results of the oxygen concentration detector 13.

The operation will be explained below.

First, the on-off valve 8 and the on-off valve 9 are opened and nitrogen gas is supplied to replace the inside of the load lock chamber 2 with nitrogen gas. During this replacement process, when the oxygen concentration inside the load lock chamber 2 becomes less than a set concentration, for example, 1 ppm, the on-off valves 8 and 9 are closed. The circulation pump 11
is driven to circulate the sealed nitrogen gas through the bypass pipe 10. In addition, in consideration of leakage from the load lock chamber 2, the on-off valve 8, and the on-off valve 9, the control device 15 is set so that the pressure inside the load lock chamber 2 is slightly higher than that of the atmosphere.
The opening and closing of the on-off valve 8 is controlled.

As described above, a wafer loading mechanism and a wafer transfer mechanism are provided inside the load lock chamber 2 to load and transfer wafers, but particles generated during these operations pass through the filter 12. It is removed during the distribution process.

When the oxygen concentration changes over time and exceeds the set value, the control device 15 controls the on-off valves 8,
The on-off valve 9 is opened, the circulation pump 11 is stopped, and nitrogen gas is allowed to flow until the oxygen concentration falls below the set value. The wafer is processed by repeating such control.

Note that the position of the filter is the same as that of the circulation pump 1.
The nitrogen gas may be circulated upstream or downstream of the circulation pump 11, and the enclosed nitrogen gas may be circulated continuously or intermittently by the circulation pump 11. Moreover, it is also possible to use various inert gases instead of nitrogen gas.

[0020]

[Effects of the Invention] As described above, according to the present invention, since vacuum is not drawn during nitrogen gas replacement, the load lock chamber can be made lightweight, and after nitrogen gas replacement, the oxygen concentration reaches a predetermined value or higher. Since nitrogen gas is passed only occasionally, the amount of nitrogen gas used is significantly reduced.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing one embodiment of the present invention.

FIG. 2 is an explanatory diagram of a conventional example.

FIG. 3 is an explanatory diagram of another conventional example.

[Explanation of symbols]

1 Reaction chamber 2 Load lock room 3 Supply pipe 4 Exhaust pipe 8 Open/close valve 9 Open/close valve 10 Bypass pipe 11 Circulation pump 12 Filter 13 Oxygen concentration detector

Claims (1)

[Claims] 1. An atmospheric gas supply pipe and an exhaust pipe are connected to a load lock chamber connected to the lower part of the reaction chamber, an on-off valve is provided in the supply pipe and the exhaust pipe, and a shut-off valve downstream of the supply pipe and an exhaust pipe are provided. The opening/closing valve of the exhaust pipe is connected to the upstream side of the opening/closing valve by a bypass pipe having a circulation pump and a filter, and an oxygen concentration detector for detecting oxygen concentration is provided in the load lock chamber, and the opening/closing is performed based on the detection result of the oxygen concentration detector. A load-lock chamber gas control device for a vertical diffusion CVD device, characterized in that it is configured to open and close a valve and drive a circulation pump.