JPH05144757A - Apparatus and method for heat treatment - Google Patents

Abstract

PURPOSE:To provide an apparatus and a method for heat treatment which uniformly and quickly heat semiconductor substrates widely distributed in a reaction chamber. CONSTITUTION:Infrared ray lamps 1, 2, 3...20 in a reaction chamber 38 are divided into two groups, a center side group and an outer side group. These groups are defined so that the border does not come above any semiconductor substrate 31. Temperature is controlled group by group, and the electric power supply per unit time is offset group by group as well. The individual infrared ray lamps have their radiation intensity adjusted.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device heat treatment apparatus and heat treatment method.

[0002]

2. Description of the Related Art A semiconductor device is subjected to heat treatment in manufacturing steps such as formation of a thermal oxide film, diffusion of impurities, and formation of a CVD film. In this heat treatment, a plurality of semiconductor substrates are placed on a disk-shaped sample table to perform lamp heating or resistance heating, and lamp heating has an advantage that the temperature rising / falling rate is extremely higher than that of resistance heating. However, in the apparatus using lamp heating, the temperature distribution in the reaction chamber is difficult to be uniform, and in particular, a temperature difference is likely to occur between the center side and the peripheral side of the disk-shaped sample table. That is, since the sample table has a certain amount of heat capacity, the center side is hard to be heated and hard to cool. On the contrary, the peripheral side is easily heated and easily cooled. Therefore, if temperature control is performed on the center side and the peripheral side under the same conditions, a temperature difference occurs between the center side and the peripheral side, and even if the sample stage is rotated, the positional relationship between the center side and the peripheral side does not change. ,
There is a problem that the semiconductor substrate mounted on the sample table is unevenly heated on the center side and the peripheral side of the sample table.

As a measure for solving the above-mentioned drawbacks, a proposal has been made by Japanese Patent Laid-Open No. 62-93378, and FIG. 1 is a schematic vertical sectional view of a heating device used in an epitaxial growth process. A gas inlet 42 and a gas outlet 43 are formed on the side wall of the reaction chamber 41, respectively. A rotatable sample table 45 on which a semiconductor substrate 44 to be heat-treated is placed is arranged in the reaction chamber 41, and a plurality of rod-shaped infrared lamps 46a, 46a ... Are equidistantly arranged above the sample table 45. They are installed side by side.

An infrared lamp 46 is provided below the sample table 45.
A plurality of rod-shaped infrared rays 46b are arranged in parallel at equal intervals in a direction orthogonal to a, 46a.
46b can be divided into groups, and the radiation intensity of the infrared lamp can be made different for each group. This proposal attempts to make the temperature inside the reaction chamber uniform by adjusting the radiation intensity of a plurality of infrared lamps according to the temperature distribution inside the reaction chamber.

[0005]

In lamp heating, the semiconductor substrate is heated by direct absorption of infrared rays emitted from the lamp and heat absorption from the sample stage. From this fact, as described above, when heating is performed by making the radiation intensity different for each group of a plurality of infrared lamps, a temperature difference occurs due to the difference in the lamp radiation intensity of the heated object corresponding to the boundary of each lamp group. Therefore, for example, when this boundary is located on the semiconductor substrate, there is a problem that a defect such as a slip due to a temperature difference occurs. The present invention has been made in view of such circumstances, and a heat treatment for uniformly and quickly heating a wide area in the reaction chamber without affecting the semiconductor substrate due to the difference in radiation intensity generated at the boundary. It is an object to provide an apparatus and a heat treatment method.

[0006]

In the heat treatment apparatus according to the present invention, a plurality of semiconductor substrates are placed on a sample table provided inside an infrared permeable reaction tube, and an infrared lamp is provided from outside the reaction tube. And a second control circuit for controlling an infrared lamp group that heats the peripheral side of the sample table. A temperature detector that detects the temperature on the center side of the sample stage and feeds back the detected value to the first control circuit; and detects the temperature on the peripheral side of the sample stage and outputs the detected value to the second control circuit. And a temperature detector that feeds back to the temperature detector.

In the heat treatment method according to the present invention, a plurality of semiconductor substrates are placed on a rotatable sample stage disposed inside an infrared permeable reaction tube, and heat treatment is performed from the outside of the reaction tube by an infrared lamp. In the method, the infrared lamp is divided into an infrared lamp group that heats the center side of the sample table and an infrared lamp group that heats the peripheral side of the sample table, the boundary of which is located outside the semiconductor substrate.
The radiant intensity of each infrared lamp group is controlled independently.

[0008]

In the heat treatment apparatus and method of the present invention, the infrared lamp group for heating the center side of the sample stage and the infrared lamp group for heating the peripheral side of the sample stage are divided into two groups. Since the infrared lamp group control circuits are fed back to the respective infrared lamp group control circuits to independently control the radiant intensity of the infrared lamp groups, the sample table can be heated so that the temperature distribution becomes uniform. Therefore, the heat absorbed from the sample table by the semiconductor substrate mounted on the sample table becomes uniform in the plane of the semiconductor substrate. Furthermore, since the boundaries of the infrared lamp groups are arranged so as not to be located on the semiconductor substrate, there is no temperature difference within the semiconductor substrate surface even if the radiation intensity of the infrared lamps differs between the lamp groups, The semiconductor substrate can be heated so that the temperature distribution becomes uniform.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be specifically described below with reference to the drawings showing the embodiments thereof. 2 and 3 are a schematic plan view and a schematic vertical sectional view, respectively, of the heat treatment apparatus according to the present invention used in the Si epitaxial growth step. The reaction chamber 38 is surrounded by an infrared permeable quartz reaction tube on its upper and lower surfaces and side walls, and has gas inlets and outlets on opposite sides. The sample stage 32 arranged in the reaction chamber 38 is made of disk-shaped carbon coated with SiC and has a rotating shaft.
It is supported by 39 and can rotate in the horizontal plane.

Outside the reaction tube 40 above the sample table 32, rod-shaped infrared lamps 1, 2, 3 ... 20, 20 orthogonal to the gas flow.
Books are arranged, and rod-shaped infrared lamps 21, 22 ... 25, and 5 and 26, 27 ... 30, 5 lamps are provided on the outer side of the reaction tube 40 below the sample table 32 in parallel with the flow of gas. It is located on both sides. Further, a temperature measuring block 37 for detecting the temperature of the peripheral portion of the sample table is arranged in the vicinity of the sample table 32. The temperature measuring block 37 is made of the same material as the sample table 32 or a material having similar thermal characteristics, and its thickness is almost the same as that of the sample table. By inserting the thermocouple 36 into the block 37 and measuring the temperature, the temperature corresponding to the temperature of the peripheral portion of the sample table can be detected. The temperature measuring block 37 may be provided over a half circumference of the outer circumference of the sample table, or may be shorter than that. Further, a thermocouple 33 is fixed to the center of the sample table 32 through the rotary shaft 39.

A reflecting mirror 40 is installed on the upper side of the infrared lamps 1, 20 ... And on the lower side of the infrared lamps 21, 22 ,. Four Si substrates 31 to be processed are placed on the sample table 32 in an equal arrangement. The reflecting mirror 40 has a concave cross section so as to surround each infrared lamp, and is configured so that the infrared rays reflected by the reflecting plate are condensed in front of each concave surface. Therefore, as described above, when the infrared lamp is divided into a group that heats the center side of the sample table and a group that heats the edge side, the upper surface of the sample table 32 corresponding to the boundary portion is divided into the center side and the peripheral side. A temperature difference is likely to occur. It is necessary to divide the infrared lamps 1, 2, 3, ... 20 above the reaction chamber 38 into groups so that the positions where this temperature difference occurs are not located on the four Si substrates. For this reason, the boundary is between the heated objects irradiated by the infrared lamps 4 and 5, and between the heated objects irradiated by 16,17. , 2, 3, 4, 17, 18, 19, 20 can be divided into B groups.

FIG. 4 is a schematic circuit diagram of the temperature controller.
In the figure, 47 is a temperature programmer that stores the power supply amount (heat pattern) per unit time, is connected to the PID feedback unit 49 via the PID feedback unit 48 and the regulator 50, and the PID feedback units 48 and 49 are 16 are respectively connected to the infrared lamps of the A group 5, 6, 7 ... 16, the B groups 1, 2, 3, 4, 17, 18, 19, 20 and the infrared lamps below the sample table.

According to the heat pattern stored in the temperature programmer 47, the PID feedback unit 48
The group lamps 5, 6, 7 ... 16 are turned on. The thermocouple 33 that detects the temperature on the center side of the sample table uses the detected value as the PID.
By feeding back to the feedback unit 48, the radiant intensity of the lamps 5, 6, 7, ...
The heat pattern from the temperature programmer 47, which is instructed to the PID feedback unit 49 in order to reduce the temperature difference between the center side and the peripheral side of the sample table 32 as much as possible to make the temperature uniform,
The offset is provided by the regulator 50.

The PID feedback unit 49 lights the lamps 1, 2, 3, 4, 17, 18, 19, 20 of the B group in accordance with the heat pattern provided with this offset. The thermocouple 36 that detects the temperature on the peripheral side of the sample table feeds back the detected value to the PID feedback unit 49, and the lamps 1, 2, 3, 4, 17, 18, 18 of the B group.
The radiant intensity of the lamps 19, 20 and the lamp below the sample table are adjusted. In addition, the infrared lamps 1, 2, 3, ...
51 is connected, and the radiation intensity can be adjusted for each infrared lamp.

By controlling with such a circuit,
The lamps in each group are supplied with power according to the heat pattern stored in the temperature programmer 47. that time,
The radiant intensity according to the difference from the set temperature is independently selected for each of the center side and the peripheral side of the object to be heated. The temperature under that condition is detected, and the detected value is fed back to uniformly heat the object to be heated to a desired temperature. Into the reaction chamber 38 thus heated, the source gas SiHCl ₃ , the additive gases PH ₃ and B ₂ H ₆ were introduced, and the epitaxial growth was performed at the reaction temperature of 1050 to 1140 ° C. Reaction chamber with gas introduction 38
Infrared lamps 1, 2, 3 ...
It can be adjusted by a span adjuster 51 connected to each of the 30.

FIG. 5 shows the film thickness distribution of the epitaxial film of the wafer formed by growing PH ₃ at 1140 ° C. as described above. From this distribution, it can be said that the variation in film thickness is approximately ± 1.2%. This indicates that the uniformity of the epitaxial film formed in the above-described embodiment is remarkably improved because the variation in the epitaxial growth film thickness due to the conventional lamp heating is approximately ± 3% in the good quality wafer. There is.

The resistivity distribution of the formed wafer was ± 1%. This represents an improvement in the uniformity of the wafer formed in the example because the resistivity distribution of the wafer epitaxially grown by the conventional lamp heating is about ± 3% for a good quality wafer. Furthermore, defects such as slips did not occur on the formed wafer.

Further, since the heat pattern offset is given between the infrared lamp groups on the center side and the peripheral side of the sample table, the objects to be heated of the respective lamp groups are changed according to the difference between the set temperature depending on the heat pattern. Since it is possible to supply power, further adjust the radiation intensity for each infrared lamp, and to supply power according to the difference between the locally different temperature of the object to be heated and the set temperature, Also, it becomes possible to perform uniform heating more quickly.
Although the infrared lamps below the sample table are not grouped into the center side and the peripheral side in the above-mentioned embodiment, when the heat capacity of the sample table is small or the sample table is thin, the sample table is not The lower infrared lamps are also grouped into the center side and the peripheral side, and the same control as that of the infrared lamps on the upper side of the sample table can be performed to obtain the same effect.

[0019]

As described above, in the heat treatment apparatus and the heat treatment method of the present invention, each group divided so that its boundary is not located on the semiconductor substrate which is the object to be heated,
Since the radiation intensity of the infrared lamp can be feedback-controlled, it is possible to uniformly and quickly heat the reaction chamber over a wide range. By performing such heating,
The present invention has excellent effects such as suppressing the occurrence of defects in a semiconductor substrate and manufacturing a uniform and high-quality semiconductor device.

[Brief description of drawings]

FIG. 1 is a schematic vertical cross-sectional view of a heating device proposed in JP-A-62-93378.

FIG. 2 is a schematic plan view of a heat treatment apparatus according to the present invention.

FIG. 3 is a schematic vertical sectional view of a heat treatment apparatus according to the present invention.

FIG. 4 is a schematic circuit diagram of a temperature controller according to the present invention.

FIG. 5 is a graph showing a film thickness distribution of an epitaxial film on a wafer formed according to an example.

[Explanation of symbols]

 1,2 ... 30 Infrared lamp 31 Semiconductor substrate 32 Sample stage 33,36 Thermocouple 38 Reaction chamber 47 Temperature programmer 48,49 PID feedback unit 50,51 Regulator

Claims (2)

[Claims] 1. A heat treatment apparatus in which a plurality of semiconductor substrates are placed on a sample table provided inside an infrared permeable reaction tube, and the semiconductor substrates are heated from outside the reaction tube by an infrared lamp. A first control circuit for heating and controlling the infrared lamp group for heating the center side of the sample stage, a second control circuit for heating and controlling the infrared lamp group for heating the peripheral side of the sample stage, and a second control circuit for controlling the center side of the sample stage A temperature detector that detects the temperature and feeds back the detected value to the first control circuit, and a temperature detector that detects the temperature on the peripheral side of the sample stage and feeds the detected value back to the second control circuit. A heat treatment apparatus comprising. 2. A method in which a plurality of semiconductor substrates are placed on a rotatable sample stage provided inside an infrared permeable reaction tube, and heat treatment is performed from the outside of the reaction tube by an infrared lamp. The lamp is divided into an infrared lamp group that heats the center side of the sample stage and an infrared lamp group that heats the peripheral side of the sample stage, with their boundaries positioned outside the semiconductor substrate, and the temperature of each group is adjusted. A heat treatment method characterized by independent control.