JPH0311621A - Heat treatment apparatus for semiconductor wafer - Google Patents

Abstract

PURPOSE:To prevent ambient gas from mixing in and to enable execution of a reaction at a prescribed temperature and in a prescribed time by lowering a reaction tube so as to cover semiconductor wafers and by putting the inside of the reaction tube in a hermetically-closed vacuum state before the semiconductor wafers are heated. CONSTITUTION:A reaction tube 5 is inserted into a heater 6 by a mechanism 7 for driving the reaction tube vertically, and thereby it is moved vertically so that it covers a boat 2. By a lowering operation of the mechanism 7, besides, the reaction tube covers semiconductor wafers 1 and the boat 2 and the inside of the reaction tube 5 is put in a hermetically-closed state. Thereafter the inside of the reaction tube 5 is put in a vacuum state by operating a vacuum pump 12, the reaction tube is inserted into the heater 6, the semiconductor wafers 1 and the boat 2 are heated with an inactive gas made to flow into the reaction tube 5, the inactive gas is replaced by a reaction gas and heat treatment is executed. Since a reaction is conducted only in the heater in this way, ambient gas is prevented from mixing in and the heat treatment can be performed at a prescribed temperature and in a prescribed time.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a semiconductor wafer heat treatment apparatus used in a semiconductor manufacturing process.

[Conventional technology]

2. Description of the Related Art In semiconductor manufacturing processes, there is a step in which a semiconductor wafer is inserted into a reaction tube maintained at a high temperature, and a reaction gas is flowed into the reaction tube to perform heat treatment.

Conventionally, this type of vertical heat treatment apparatus has the following configuration and operating functions. That is, the reaction tube is placed in a heater and heated to a high temperature, and an inert gas is flowed into the reaction tube.

Next, a boat containing semiconductor wafers horizontally and in parallel is inserted into the reaction tube. After insertion, the gas in the reaction tube is switched from an inert gas to a reaction gas, and the semiconductor wafer is heat-treated. After a predetermined processing time has elapsed, the reactive gas is switched again to an inert gas, and the boat containing the semiconductor wafers is taken out.

A conventional heat treatment apparatus will be explained using figures. FIG. 3 is a cross-sectional view showing an outline of its configuration.

Semiconductor wafers] are housed horizontally and in parallel in the boat 1-2, the boat 2 is mounted on a heat insulating cap 3, and the heat insulating cap 3 is connected to a vertical drive mechanism section 4. Reaction tube 5
is fixed inside the heater 6.

The gas pipe 13 is connected inside the heater 6 to the head of the reaction tube 5 along the side surface of the reaction tube 5, and the inert gas and reaction gas are switched in the gas unit 10, and the pressure and flow rate are adjusted. The gas flows into the reaction tube 5 through the gas pipe 13. An exhaust pipe 14 is connected to the reaction tube 5, and the gas inside the reaction tube 5 is exhausted through the exhaust pipe 14.

Here, the boat 2, the heat insulating cap 3, the reaction tube 5, and the waste pipe 13 are generally made of high-purity quartz or the like in order to prevent impurity diffusion at high temperatures.

Semiconductor wafers 1 are housed at regular intervals in grooves cut into ports 2, and boat 2 is mounted on a heat insulating cap 3. The inside of the reaction tube 5 is heated to a high temperature by the heater 6, and the inert dregs whose pressure and flow rate are adjusted by the dregs unit 10 flows into the reaction tube 5 through the dregs pipe 1B, and is filled with inert gas. There is.

Next, the semiconductor wafer 1, boat 2, and insulation cap 3 are
The bow 1 is inserted into the reaction tube 5 by the upward movement of the horizontal portion 4 of the vertical drive machine, and is heated to a high temperature. After insertion, the reaction mass or reaction tube 5 whose pressure and flow rate are adjusted in the mass unit 10
heat treatment is carried out. After a predetermined period of time has elapsed, the gas is switched to inert gas again in the gas unit 10, and the reaction gas is discharged to the outside of the reaction tube 5 through the exhaust pipe 14. The semiconductor wafer 1, boat 2, and insulation cap 3 are
The hole L is lowered by the lowering operation of the vertical drive mechanism 4, and after lowering, it is cooled to room temperature and the heat treatment is completed.

[Problem to be solved by the invention]

In the conventional semiconductor wafer heat treatment apparatus described above, the semiconductor wafer is not isolated from the surrounding atmosphere when it is inserted into the reaction tube, so the surrounding atmosphere is drawn into the reaction tube, and the semiconductor wafer being heated and the reaction gas in the surrounding atmosphere are mixed. reaction, resulting in heat treatment that is difficult to control.

In addition, the structure has a large temperature change from the reaction tube opening to the inside of the reaction tube, and since semiconductor wafers are vulnerable to sudden temperature changes, it is necessary to slow down the bottom operation of the boat. There is a problem that the thermal history is significantly different.

Furthermore, since the high-temperature semiconductor wafer is exposed to the surrounding atmosphere when the semiconductor wafer is taken out of the reaction tube, there is a drawback that the semiconductor wafer reacts with the reaction gas in the surrounding atmosphere.

In conventional heat treatment apparatuses, as a countermeasure to the above-mentioned problems, the flow rate of inert scum is increased when carrying in semiconductor wafers and ports, but this has the problem of worsening the temperature distribution within the reaction tube.

In addition, as another countermeasure, the inside of the reaction tube is kept at a low temperature, the semiconductor wafer is inserted, and after the insertion is completed, the semiconductor wafer is heated, and after the specified temperature is reached, the inert gas is switched to the reactive gas, and after a certain processing time has passed, the semiconductor wafer is inserted again into the low temperature state. Although the semiconductor wafer is transported out of the wafer in the same state, there is a problem in that the heat treatment time is extremely long.

[Means to solve the problem]

The present invention provides a semiconductor wafer heat processing apparatus equipped with a boat vertical drive mechanism that carries a boat containing semiconductor wafers up and down, and inserts and unloads the boat into a vertical reaction tube.
A semiconductor wafer heat treatment apparatus provided with a reaction tube vertical drive mechanism that moves the reaction tube up and down to take it in and out of a heater, and a vacuum pump that lowers the reaction tube, seals the hoard and semiconductor wafer, and evacuates the inside of the reaction tube. It is.

〔Example〕

Next, the present invention will be explained with reference to the drawings.

FIG. 1 is a sectional view showing the configuration of an embodiment of the present invention.

The semiconductor wafers 1 are stored horizontally and parallelly in the bowls 1 to 2, the boats 2 are mounted on a heat insulating cap 3, and the heat insulating cap 3 is connected to a lower drive mechanism 4 in the hoard.

The heat insulating cap 3 is connected to an injector 8 that guides gas to the upper part of the bows 1 and 2, a gas pipe that guides waste to the injector 8, and an exhaust pipe 1]. A waste unit 10 is connected to the waste pipe 9 for switching gas and adjusting flow rate and pressure. A vacuum pump 12 is connected to the exhaust pipe 1.

Gas piping 9 and exhaust piping] 0 is designed to expand and contract at the lower part of the insulation cap 3 because the insulation cap 3 moves up and down. The reaction tube 5 is inserted into the heater 6 by a reaction tube vertical drive mechanism 7, and is moved up and down to cover the boat 2.

FIGS. 2(a), 2(b), and 2(C) are operational diagrams of an embodiment of the present invention.

As shown in Figure (a), the reaction tube 5 is pushed up by the reaction tube vertical drive mechanism 7 and housed in the heater 6. The heat insulating cap 3 is lowered by the boat vertical drive mechanism 4, and the semiconductor wafers 1 are placed on the boat 2 in an orderly manner at equal intervals.
The boat 2 is mounted on a heat insulating cap 3.

Next, as shown in Figure (b'), the reaction tube 5 covers the semiconductor wafer 1 and the boat 2 by the downward movement of the reaction tube vertical drive mechanism section 7, and the inside of the reaction tube 5 becomes sealed. Thereafter, the vacuum pump 12 is operated to bring the inside of the reaction tube 5 into a vacuum state.

Next, as shown in Figure (c), the reaction tube vertical drive mechanism section 7
The reaction tube 5 is inserted into the heater 6 while the inside thereof is kept in a vacuum state by the interlocking upward movement of the boat vertical drive mechanism section 4. Then, an inert gas flows into the reaction tube 5 through the gas pipe 9, and the semiconductor wafer 1- and hoard 2 are heated.

Next, the inert gas is switched to a reactive gas and heat treatment is performed. After a predetermined period of time has elapsed, the vacuum pump 12 is operated again to create a vacuum inside the reaction tube 5, and the reaction tube vertical drive mechanism 7 and the boat vertical drive mechanism 4 move down in conjunction with each other, opposite to the time of insertion, and the reaction begins. Inert gas is introduced into the tube 5 for cooling.

Finally, only the reaction tube 5 is inserted into the heater 6 by the upward movement of the reaction tube vertical drive mechanism 7, and the semiconductor wafer 1 and the board 1-2 are taken out from the heat insulating cap 3.

〔Effect of the invention〕

As explained above, in the present invention, before heating the semiconductor wafer, the reaction tube is lowered to cover the semiconductor wafer and the inside of the reaction tube is brought into a sealed vacuum state, thereby eliminating the mixing of the surrounding atmosphere when heating the semiconductor wafer and causing the reaction to occur. is carried out only during the specified temperature time in the heater.

In addition, since there is no problem of contamination with the surrounding atmosphere, the speed at which semiconductor wafers are inserted into and taken out of the heater can be increased.
The difference in thermal history between the upper and lower parts of the boat can be reduced.

As described above, the reaction is carried out only within the heater, making it possible to perform heat treatment that reduces the difference in thermal history between the upper and lower parts of the boat, thereby making it possible to heat-treat semiconductor wafers of high quality and without variation.

[Brief Description of the Drawings] Fig. 1 is a sectional view showing an embodiment of the present invention, Fig. 2(a)
, (b) and (c) are operational diagrams thereof, and FIG. 3 is a sectional view showing a conventional heat treatment apparatus. DESCRIPTION OF SYMBOLS 1...Semiconductor wafer, 2...Boat, 3...Insulating cap, 4...Boat vertical drive mechanism section, 5...Reaction tube, 6...Heater, 7...Reaction tube vertical drive Mechanism section, 8... Injector, 9... Gas piping, 10...
- Gas unit, 11... Exhaust piping, 12... Vacuum pump, 13... Gas piping, 14... Exhaust piping.

Claims (1)

[Claims] In a semiconductor wafer heat treatment apparatus equipped with a boat vertical drive mechanism that carries a boat containing semiconductor wafers and moves the boat up and down to insert and take out the boat into and out of a vertical reaction tube, a reaction tube that moves the reaction tube up and down to take it in and out of a heater. 1. A semiconductor wafer heat treatment apparatus, comprising: a vertical drive mechanism; and a vacuum pump that lowers the reaction tube, seals the boat and the semiconductor wafer, and evacuates the inside of the reaction tube.