JPS62108532A - Heat treatment method for semiconductor wafer - Google Patents

Abstract

PURPOSE:To prevent the leakage of currents and the dispersion of the activation of an impurity by evacuating the inside of a reaction pipe into which a semiconductor wafer is arranged, injecting an inert gas into the reaction pipe and thermally treating the semiconductor wafer at a fixed temperature in an inert gas atmosphere. CONSTITUTION:A wafer 19 is placed onto a susceptor 18, and inserted into a vacuum spare chamber 8. In this case, a valve 12 for exhaust and a valve 16 for adjusting the injection of an inert gas are closed, valves 13, 15 for exhaust are opened, the diffusion pump 11 side is opened in a valve 14 for exhaust,and the inside of a heat treatment chamber 7 is brought to a vacuum state. The valve 13 is closed and the vacuum spare chamber 8 side of the valve 14 is opened, the valve 12 is opened when the inside of the vacuum spare chamber 8 reaches the sufficient degree of vacuum, and the susceptor 18 is moved to the heat treatment chamber 7. Regular exhaust is conducted, the valve 15 is closed and the valve 16 is opened at the desired degree of vacuum, the inert gas is injected into the heat treatment chamber 7, and the wafer 19 is irradiated by the beams and heat of tungsten halogen lamps 20 after the pressure of the chamber 7 reaches a predetermined pressure, thus thermally treating the wafer. Accordingly, the wafer having excellent characteristics in which there are hardly the leakage of currents on the surface and the dispersion of activation is obtained.

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to a method of heat treatment of semiconductor wafers.

(Prior Art) Generally, heat treatment of wafers in the manufacturing process of semiconductor devices involves activation after implantation of impurity ions.

This is an important process for sintering the aluminum electrode, improving the characteristics of the interface between silicon and silicon oxide, and removing strain.

Conventionally, the heat treatment method generally used a heat treatment apparatus using, for example, a halogen lamp as a heat generation source, as shown in FIG. That is, FIG. 2 shows a schematic configuration diagram showing an example of a heat treatment apparatus for wafers called a lamp annealing apparatus. Opening 5 into which the susceptor 4 is inserted or taken out. This structure also includes a halogen lamp 6 for heating the wafer 3.

In such a conventional heat treatment apparatus, an inert gas such as nitrogen gas is constantly injected into a reaction tube 1 from an injection port 2 at a flow rate of several Q per minute, and a susceptor 4 on which a wafer 3 is placed is passed through an opening 5. The susceptor 4 is inserted and heated with a halogen lamp 6, and when the treatment is completed, the susceptor 4 is pulled out from the opening 5 and the wafer 3 is taken out.

(Problems to be Solved by the Invention) In the conventional heat treatment method using the above-mentioned apparatus, when setting the wafer 3 in the reaction tube 1 using the susceptor 4,
Contaminants in the atmosphere easily enter the reaction tube 1 through the opening 5, and similarly, contaminants in the atmosphere are sent into the reaction tube 1 while remaining attached to the wafer 3. Therefore, when the ion-implanted wafer 3 is activated by heat treatment, the impurities in the above-mentioned contaminants will also be activated, and semiconductor devices manufactured using the wafer 3 will be affected by current leaks,
This has the disadvantage of causing variations in the activation of necessary impurities.

(Means for Solving the Problems) As described above, in view of the drawbacks of the conventional wafer heat treatment method, the present invention provides a process in which the inside of the reaction tube in which the wafer is placed is evacuated and replaced with an inert gas. By simultaneously performing heat treatment on the wafer, the aforementioned drawbacks are eliminated.

(Function) In the heat treatment method of the present invention according to the method described above, after placing the wafer in the reaction tube, the inside is evacuated, so that air pollutants present inside the reaction tube and on the wafer surface are removed. Therefore, the drawbacks caused by conventional heat treatments as described above are eliminated.

(Example) The present invention will be explained below by way of an example using the drawings. FIG. 1 is a schematic configuration diagram of a heat treatment apparatus showing an embodiment of the present invention, which includes a reaction tube, a vacuum evacuation device for evacuating the inside thereof, an inert gas injection device, and a heating device for automatically controlling heat treatment. , and an automatic susceptor insertion device.

That is, 7 is a heat treatment chamber, 8 is a vacuum preparatory chamber, which constitute the reaction tube 9, and 10 is a rotary pump, a diffusion pump 11, and an exhaust valve 1 for regulating exhaust.
2 to 15 to form the vacuum evacuation device, and an inert gas injection control valve 16 to be injected into the heat treatment chamber 7;
and an inert gas supply device 17 to constitute the inert gas injection device. Further, a halogen lamp 20 for heating the wafer 19 placed on the susceptor 18
．． and a reflector plate 21 that reflects light and heat therefrom. The heating device includes a temperature control device 23 that automatically controls the temperature of the heat treatment chamber 7 using a thermocouple 22, and 24 is an automatic insertion device for the susceptor 18.

In the heat treatment apparatus used in the present invention configured as described above, first, with the wafer 19 placed on the susceptor 18, the exhaust valve 13 is opened and the susceptor 18 is inserted into the vacuum preliminary chamber 8. At this time, the exhaust valve 12 and the inert gas injection adjustment valve 16 are closed, and the exhaust valves 13 and 1 are closed.
5 is open, and the exhaust valve 14 is open on the left side (diffusion pump ll side) in the figure, and the inside of the heat treatment chamber 7 is in a vacuum state.

Next, by closing the exhaust valve 13 and opening the exhaust valve 14 on the left side in the figure (vacuum preliminary chamber 8 side),
Make the inside of the vacuum preparatory chamber 8 almost a vacuum, and when it reaches a sufficient degree of vacuum, open the exhaust valve 12 to remove the vacuum preparatory chamber 8.
The susceptor 18 inserted therein is moved to the heat treatment chamber 7. After that, the exhaust valve 12 is closed and the exhaust valve 14 is opened on the diffusion pump 11 side, and then the exhaust valve 15 is opened to perform full-scale exhaust, and when the desired degree of vacuum is reached, the exhaust valve 15 is opened. After closing the inert gas injection control valve 16, for example, nitrogen gas is injected into the heat treatment chamber 7 as an inert gas, and after the pressure reaches a predetermined level, the light and heat from the halogen lamp 20 is turned off. The wafer 19 is irradiated and heat treated.

After the above heat treatment is completed, inert gas injection control valve 1
6 is closed, the exhaust valve 12 is opened, and the exhaust valve 14 is opened on the vacuum preliminary chamber 8 side, and then the susceptor 18 is moved from the heat treatment chamber 7 to the vacuum preliminary chamber 8.
When those chambers reach the specified degree of vacuum, the exhaust valve 1
2 is closed so that the diffusion pump 11 side of the exhaust valve 14 is opened, then the exhaust valve 15 is opened, and then the exhaust valve 13 is opened to take out the susceptor 18 from the vacuum preliminary chamber 8 and remove the wafer. The heat treatment of step 19 is completed. Note that the automatic insertion device 24 is used to insert and remove the susceptor 18, and the thermocouple 22 operates as a temperature sensor, thereby operating the temperature adjustment device 23.

The method of the present invention has been described above, and the feature of the apparatus used is that it is equipped with a vacuum preparatory chamber 8 and is designed to shorten the time required to evacuate the heat treatment chamber 7 and increase the throughput. In the above embodiment, the halogen lamp 20 is used as the heating source, but the heating source is not limited to this, and heater heating, high frequency heating, etc. may also be used.

(Effects of the Invention) According to the present invention, an inert gas is introduced into the reaction tube which is kept in a vacuum state, and heat treatment is performed in that environment. Therefore, the heat treatment is performed without contamination entering the wafer surface. In a wafer that has been heat-treated by implanting ions, only the implanted impurity ions are activated, and therefore, a semiconductor device using a wafer that has been heat-treated by the method of the present invention is
It has good characteristics with almost no surface current leakage or activation variation.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram illustrating a wafer heat treatment apparatus used in the present invention, and FIG. 2 is a schematic diagram of a conventional wafer heat treatment apparatus. 7... Heat treatment chamber, 8... Vacuum preliminary chamber, 9...
Reaction tube, 10... rotary pump, 11... diffusion pump, 12 to 15... exhaust valve, 16...
Inert gas injection adjustment valve, 17... Inert gas supply device, 18... Susceptor, 19... Wafer, 20... Halogen lamp, 21... Reflector,
22...Thermocouple, 23...Temperature control device, 24...
・Automatic insertion device.

Claims (2)

[Claims] (1) In the heat treatment of semiconductor wafers, the inside of the reaction tube in which the semiconductor wafers are placed is evacuated, and then
A method for heat-treating a semiconductor wafer, comprising injecting an inert gas into the reaction tube and heat-treating the semiconductor wafer at a predetermined temperature in the inert gas atmosphere. (2) The method of heat treating a semiconductor wafer according to claim (1), wherein the heat treatment is carried out simultaneously with the injection of the inert gas.