JPH01248626A - Device for heat treatment of wafer - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Summary] A wafer heat treatment apparatus with a new configuration heat-treats a semiconductor wafer at a high temperature. It is equipped with a heating section that heats the wafer to a certain temperature, and a temperature decreasing section that lowers the temperature from the predetermined high temperature to a predetermined low temperature at a predetermined rate. It is characterized in that the wafers are sent one by one from the heating section to the temperature lowering section, and the temperature is lowered at a predetermined rate to a predetermined low temperature in the temperature lowering section.

[Industrial application field]

The present invention relates to a wafer heat treatment apparatus having a novel configuration for heat treating semiconductor wafers at high temperatures.

Since the crystal quality of semiconductor wafers (hereinafter referred to as wafers) has a great influence on semiconductor devices such as ICs and LSIs, homogenization of the crystals is an important issue.

[Prior art and problems to be solved by the invention] As is well known, wafers are created by slicing a silicon single crystal ingot created by a pulling method (Czochralski method), etc. The inclusion of trace amounts of impurities is unavoidable, and in particular, the inclusion of oxygen (02), carbon (C), etc. is an unavoidable problem. Therefore, crystal defects occur in wafers formed by slicing due to the influence of impurities, making it difficult to eliminate all defects.
Intrinsic gettering (intrinsic gettering) to create a nude zone (a layer with no crystal defects)
c getting). Oxygen is rather required for this intrinsic gettering effect, and in order to uniformly form a defect-free layer on the surface, it is desirable that the amount of oxygen is precipitated and distributed uniformly over the entire wafer.

Conventionally, heat treatment has been performed to uniformize the crystal quality of wafers, such as the amount of oxygen precipitated, and to erase the thermal history, but this heat treatment is a high temperature treatment of 1200 ° C or more. The high-temperature heat treatment is a batch processing method in which dozens of wafers are made into 10 lots (lot H group) and the 10 wafers are heat-treated at once by being inserted into an apparatus such as a resistance heating furnace. However, in this batch processing method, the following problems occur because the temperature of all 10-foot wafers is raised and lowered at once inside or outside the furnace.

That is, it is extremely difficult to uniformly raise or lower the temperature of all wafers at a uniform temperature, and in particular, it is nearly impossible to uniformly raise or lower the temperature at a uniform temperature in a heat treatment apparatus that experiences large temperature changes. Furthermore, there are large variations in temperature distribution within a single wafer, resulting in non-uniformity in the amount of oxygen precipitated, and slip lines are likely to occur.

By the way, the inventors have discovered that the quality of silicon wafers does not depend only on the high or low heat treatment temperature, but that the rate of cooling from the heat treatment temperature significantly affects the crystal quality, and in particular, the rate of temperature decrease has a large effect on controlling the amount of oxygen precipitated. I figured out what was going on (
(See Japanese Patent Application No. 62-295527).

Based on the results, the present invention proposes a wafer heat treatment method for the purpose of uniformizing the crystal quality such as the amount of oxygen precipitated within the wafer.

[Means to solve the problem]

Its purpose is to include a heating section that heats to a predetermined high temperature and a temperature decreasing section that lowers the temperature from the predetermined high temperature to a predetermined low temperature at a predetermined rate.The heating section holds a plurality of wafers and performs heat treatment. This is achieved by a wafer heat treatment apparatus configured to send the wafers one by one from the heating section to the temperature lowering section, where the temperature is lowered at a predetermined rate to a predetermined low temperature.

[For production]

That is, in the present invention, in order to uniformize the temperature distribution within one wafer and lower the temperature uniformly, a large number of wafers are taken out one by one from the heating section where they are being heat-treated to the cooling section, and the wafers are heated at a predetermined temperature in the cooling section. The temperature is lowered to a predetermined low temperature at a rapid rate. Then,
By controlling the temperature decreasing rate, it is possible to obtain a wafer with uniform crystal quality, such as a constant amount of precipitated oxygen.

〔Example〕

Hereinafter, embodiments will be described in detail with reference to the drawings.

FIG. 1 shows a wafer heat treatment apparatus according to the present invention, and the entire heat treatment apparatus consists of a pretreatment chamber 1. High temperature heating chamber 2. It consists of a post-processing chamber (cooling chamber) 3, and a resistance heating element 4 is disposed in contact with the outer wall of the high-temperature heating chamber 2 to heat it to a high temperature.

Further, the post-processing chamber 3 is provided with an infrared lamp heater 5 that lowers the temperature of one wafer W while controlling the temperature lowering rate, and the inside of the apparatus is in a nitrogen gas atmosphere. A wafer stage 11 is arranged in each chamber, and a large number of wafers W are placed on the wafer stage 11.
．． Reference numeral 13 denotes a wafer handling device; the wafer handling device 12 transports the wafers W one by one from the pretreatment chamber l to the high temperature heating chamber 2, and the wafer handling device 13 transports the wafers W one by one from the high temperature heating chamber 2 Send it to the processing chamber 3. The wafer stage, wafer handler, etc. are made of transparent quartz, and the wafer W is mounted thereon while being held in contact with it at three or four points in a linear manner, and is moved in a linear manner. And, Sl, S2
．． S3. Both S4 and S5 are shutters for preventing heat dissipation, and are made of, for example, a tungsten plate.

Next, to explain the heat treatment method, an example of the heat treatment temperature profile is shown in FIG. The profile is to cool down to ℃ and then let it cool naturally.

First, the wafers W are sent one by one from the pretreatment chamber 1 to the high temperature heating chamber 2 using the wafer handling device 12, and at least one wafer W is transferred to the high temperature heating chamber 2 (heating section).
Hold for at least 5 minutes, up to 1 hour. Then, the wafer handling device 13 sends the wafers W one by one from the high-temperature heating chamber 2 to the infrared lamp heater section 5 (temperature lowering section) in the post-processing chamber 3, and the heater temperature is lowered at a cooling rate of 50°C/min. It is cooled down to 700° C. while being controlled, and when it reaches 700° C., it is further pulled out and allowed to naturally cool down to room temperature in the post-processing chamber 3.

On the other hand, in synchronization with the cooling withdrawal time of this one wafer,
The wafers W are fed one by one from the pretreatment chamber 1 to the high temperature heating chamber 2. It is also possible to automate these operations, and of course the opening and closing of the shutter is also performed automatically.

If such a wafer heat treatment equipment is used and the wafer is heat treated according to the above temperature profile, the entire surface of the wafer will be heated uniformly, and the wafer will be cooled while controlling the temperature uniformly, removing the thermal history of the wafer and eliminating oxygen precipitation. Control quantity.

The above example is an example in which the feeding of wafers is carried out one by one in synchronization with the sending out, but in this way, even if the heat capacity of the heating section (high-temperature heating chamber 2) is limited, a constant number of wafers is constantly fed. Since the wafer is held in the heating section, fluctuations in the heating temperature can be suppressed. However, if the heat capacity of the heating section is sufficiently large, a plurality of wafers or 10 wafers may be fed into the heating section at a time regardless of the wafer delivery.

The wafer heat processing apparatus according to the present invention can be said to be a mixed processing method of batch processing method and single wafer processing method, and one of its features is a heating section with a large heat capacity and a heating section with a small heat capacity (temperature control). This is because it has an easy-to-cool temperature section.

〔Effect of the invention〕

As is clear from the above description, according to the present invention, it is possible to control the amount of oxygen precipitated and to obtain a wafer with uniform crystal quality, which greatly contributes to improving the performance of semiconductor devices.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing a wafer heat treatment apparatus according to the present invention; FIG. 2 is a heat treatment temperature profile diagram. In the figure, W is wafer, 1 is a pretreatment chamber; 2 is a high temperature heating chamber (heating section); 3 is a post-processing chamber (cooling section), 4 is a resistance heating element; 5 is an infrared lamp heater, 11 is a wafer stage, 12 and 13 are wafer manipulators;

Claims (1)

[Claims] It is equipped with a heating part that heats to a predetermined high temperature and a temperature lowering part that lowers the temperature from the predetermined high temperature to a predetermined low temperature at a predetermined rate, and the heating part holds and heat-treats a plurality of wafers, A wafer heat processing apparatus characterized in that the wafers are then sent one by one from the heating section to the temperature lowering section, and the temperature is lowered at a predetermined rate to a predetermined low temperature in the temperature lowering section.