JPH07200077A - Heat treatment device - Google Patents

Abstract

PURPOSE:To provide a temperature controller capable of achieving uniform and highly accurate temperature control at all times. CONSTITUTION:This device is provided with a rotatable susceptor on which a substrate to be treated is to be mounted, a heating means 5 provided with plural heating parts for heating the substrate to be treated mounted on the susceptor to a desired temperature, a temperature measuring means 6 provided with plural temperature measuring parts for measuring the temperatures at plural points near the substrate to be treated, an affecting degree measuring means for measuring the affecting degrees of the respective heating parts to the respective temperature measuring parts and a control means for feeding back the measured results of the temperature measuring means, considering the output of the affecting degree measuring means and controlling the respective heating parts so as to let measured values obtained from the respective temperature measuring parts of the temperature measuring means be a target value.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat treatment apparatus, and more particularly to temperature control thereof.

[0002]

2. Description of the Related Art When a temperature of a substrate to be processed is controlled in a heat treatment apparatus for the substrate to be processed, if the temperature distribution is not uniform, crystal defects may be generated on the substrate to be processed.
Further, in the chemical vapor deposition process, the in-plane distribution may be deteriorated due to the different deposition rate. Further, in the atmosphere of the substrate to be processed, a complicated interference system is formed due to gas flow, heat conduction, rotation of the susceptor, and the like. Therefore, when controlling the temperature of the substrate to be processed in the heat treatment apparatus for the substrate to be processed, it is necessary to make the temperature distribution uniform and prevent crystal defects from occurring on the substrate to be processed.

Conventionally, in order to make the temperature of the substrate to be processed uniform, a susceptor 3 for mounting the substrate 2 to be processed is shown in FIGS. 8 and 9 as a single-wafer type device and a batch type device, respectively.
A plurality of temperature measuring units 6 (here, center,
(right, left, front, rear) are installed, and control is performed so that these temperatures become equal. In this heating section, there is a heating section in which a plurality of heating means are arranged as shown in FIG. 7 in consideration of influences of gas flow, heat conduction, rotation of a susceptor, and the like. Here, transparent quartz, S
A reactor 1 made of US or the like, a circular susceptor 3 placed inside the reactor 1 for mounting the wafer 2, a motor 4 for rotating the susceptor 3, and a plurality of divided heaters 2 for heating the wafer 2. The heating unit 5 and the temperature measuring unit 6 for introducing gas into the reaction furnace and including a plurality of temperature measuring means provided in a plurality of regions on the susceptor are provided, and the control amount calculating unit 10 measures the temperature. The heating unit 5 according to the measurement value of the unit 6
The heating means is controlled by feedback (FIG. 10).

[0004]

However, in this method, the amount of heat given to the temperature measuring section on the susceptor by the heating section controlled by each feedback (FB) loop is as shown in FIG.
As shown in Fig. 3, since there is a crisp region and a discontinuous surface occurs between each region, a steep temperature gradient is likely to occur on the substrate to be processed, crystal defects may occur, and the deposition rate in the chemical vapor deposition process may be increased. However, the in-plane distribution may deteriorate.

Further, in the atmosphere of the substrate to be processed, a complicated interference system is generated due to gas flow, heat conduction, rotation of the susceptor, and the size of the substrate to be processed is variable. In some cases, there is a problem that the performance changes depending on the size of the reaction chamber including the substrate to be processed and the susceptor, and the installation positions of the heating unit and the temperature measuring unit.

Therefore, the present invention has been made in view of the above circumstances, and an object of the present invention is to provide a heat treatment apparatus for a substrate to be processed which can always achieve more uniform and highly accurate temperature control.

[0007]

Therefore, in the present invention, a rotatable susceptor for mounting a substrate to be processed and a plurality of heating units for heating the substrate to be processed mounted on the susceptor to a desired temperature are provided. And a temperature measuring unit having a plurality of temperature measuring units for measuring temperatures at a plurality of points in the vicinity of the substrate to be processed, and a degree of influence of each heating unit on each temperature measuring unit is measured. The measurement value obtained from each temperature measuring unit of the temperature measuring unit becomes the target value while feeding back the measurement result of the influence measuring unit and the measurement result of the temperature measuring unit and considering the output of the influence measuring unit. like,
And a control means for controlling each heating unit.

[0008]

According to the above construction, the influence of the measured value PV of the temperature measuring means from the adjacent heating portion is taken into consideration due to the influence of the gas flow, heat conduction, rotation of the susceptor, etc. in the arrangement atmosphere of the substrate to be processed. Since the temperature of each heating unit is controlled, it is possible to prevent a temperature gradient from occurring and to make the temperature distribution uniform, so that crystal defects may occur on the substrate to be processed, or chemical defects may occur. It is possible to prevent nonuniformity of the deposition rate in the deposition process.

Further, since the degree of influence changes depending on the ambient temperature and the set temperature, the control accuracy is further improved by updating the influence successively.

[0010]

Embodiments of the present invention will now be described in detail with reference to the drawings.

FIG. 1 is a diagram showing a control circuit in a CVD apparatus according to an embodiment of the present invention, and FIG. 2 is a diagram showing a control rate of each heating means.

As shown in FIG. 7, this CVD apparatus comprises a reaction furnace 1 made of transparent quartz, SUS, etc., and a circular susceptor 3 placed inside the reaction furnace 1 for mounting a wafer 2 thereon.
And the motor 4 for rotating the susceptor 3 and the reactor 1
20 blocks of heating means 5 _j (j = 1
~ 20) (here, 10 halogen lamps each at the top and bottom, a total of 20 halogen lamps) and a heating unit 5 for introducing gas into the reaction furnace and at five temperatures provided in five regions on the susceptor. The temperature measuring unit 6 including a measuring unit is provided, and the heating unit 5 _j (j = 1 to 20) of the heating unit 5 is controlled according to the measured value of the temperature measuring unit 6. In order to consider the influence of the command value of the adjacent block in the process, the control amount computing unit 9 calculates the control amount according to the command of the load unit 8 controlled by the load adjusting unit 7, and the uniform temperature control is performed. It is characterized by having done. The temperature measuring unit 100 is composed of a radiation thermometer and measures from the back surface of the susceptor.

The load adjusting unit 7 is an ambient temperature adjusting unit 7.
01, an influence degree measuring unit 702, an influence degree measuring command unit 703 that gives an instruction to measure the influence degree, and a load learning unit 704.

The command value to the load section 8 is given by the following equation.

[0015] Here, MV 'is a command value to the heating unit, MV is a control amount obtained by the control amount calculation unit and the load learning unit, W is a control rate of each heating unit, and j is a heating unit number. Further, g is a minute value that is set in order to make the amount of heat applied to the substrate to be processed a continuous surface, so that the command value in the heating unit is influenced by the command values in the heating units on both sides. Further, the function f is a function for converting xj into 0 to 1, and there are a piecewise linear function, a logistic function, and the like. Here, the logistic function is used.

[0016] Furthermore, the degree of influence of each heating unit on each temperature measuring unit is ef
Let f _jk be the value at each temperature measurement unit and PV k Becomes Here, k is the number of the temperature measuring unit.

Next, the operation of this device will be described.

As shown in the flow chart in FIG. 3, the ambient temperature controller 701 regulates the ambient temperature. First, the ambient temperature is set to, for example, 1000 ± 100 ° C. (step 101). After this, the degree of influence is measured (step 102) and the load is adjusted (step 10).
3), the control is completed (step 104).

First, the adjustment of the ambient temperature will be described. This step is performed because the degree of influence varies depending on the range in which the temperature control is performed. First, as shown in the flow chart of FIG. 4, the ambient temperature control unit 701 regulates the ambient temperature. (Step 201).

Then, the first switch A operates downward and the second switch B operates upward, so that the inputs from the control amount calculation unit 9 and the load unit 8 are cut off (step 202).

Then, the fourth switch D operates upward,
The input from the influence degree measurement command unit 703 is cut off (step 203).

Then, it is judged whether or not the measured value by the temperature measuring unit has reached the vicinity of the set temperature (step 204). If it is judged that the measured value has reached, the adjustment is terminated and the temperature has been reached. If it is determined that there is no such change, the command value to each heating unit is changed, and the adjustment is continued until the command value is reached. In addition, the command value to each heating part shall be an equivalent value here.

When the adjustment of the ambient temperature is completed in this way, the degree of influence is measured.

First, as shown in FIG. 5, a command value for influence measurement is set in the influence measurement command section 703 (step 3).
01).

The third switch C moves to the leftmost position (step 302).

Then, the fourth switch D is operated downward (step 303), and the influence degree measurement instruction value is input from the influence degree measurement instruction section to the first heating section.

In this state, the amount of change in the measured value at each temperature measuring unit is stored in the influence degree measuring unit (step 30).
4). When this storage operation is completed, the third switch C is shifted to the right by one and the heating unit number is updated (step 3
05). In this way, the degree of influence of each heating unit on each temperature measuring unit is sequentially measured. Then, it is judged whether or not the heating unit number has reached 20 (step 306), and if it has not reached 20, the process returns to step 305. When the measurement is completed in this way, the measured amount of change is normalized to 0 to 1 and these are stored as the degree of influence (step 307). This change amount is due to the influence of the temperature change of each heating unit on each temperature measuring unit.

Next, the adjustment of the load W will be described with reference to FIG.

First, when the first switch A operates downward (step 401), the input from the load learning unit 704 is given to the load unit 8. Then, the second switch B operates downward (step 402), and the command value from the load section in each heating section is input to the control amount calculation section 9.

Then, n is set to 0 (step 40
3), PV ^* is a desired value for the measured value PV, and M
As Vj (0) and PVk ^* (0) (step 404), iterative learning by the steepest descent method as shown below is performed (step 405).

[0031] Here, ε is a constant for updating W, and is assumed to be a sufficiently small positive number. When E becomes sufficiently small (step 406), n is incremented (step 407) and learning is performed.

Then, it is judged whether or not n is larger than 5 (step 408), and when it exceeds 5, the first switch A operates upward (step 409) and the normal temperature control is started.

FIG. 2 shows the control rate of the heating portion in each FB by this learning. In this way, the amount of heat given to the temperature measuring part on the susceptor by the heating part controlled by each FB forms a continuous region.

In this way, continuous and uniform temperature control can be performed.

Using this apparatus, the silicon wafer 2 is placed on the susceptor 3, and the silicon wafer 2 is inserted through the gas introduction port.
A reactive gas is introduced toward the wafer and the temperature of the back surface of the susceptor is measured with a radiation thermometer. Based on this measured value, the light quantity of the heating means (upper and lower 10 infrared lamps, 20 in total) is controlled The temperature is adjusted with high precision.

Here, the wafer temperature is set to 850 to 1200 ° C.

Next, an epitaxial growth method using this epitaxial growth apparatus will be described.

First, the silicon wafer 2 is placed on the susceptor 3, and the susceptor 3 is rotated by the rotating means (motor) 4 via the rotating shaft.

Then, nitrogen gas is supplied from the gas inlet to purge the inside of the reaction furnace 1 with N ₂ .

[0040] Subsequently, the supply hydrogen H ₂ gas from the gas inlet to the reactor 1 was purged with H _2, H ₂ atmosphere epitaxial growth temperature of the wafer by infrared lamp 5 in (9
00 to 1050 ° C.).

When the growth temperature is reached through the process of uniform temperature control according to the method of the present invention, SiH ₄ heated to the same temperature and diluted with H ₂ is supplied from the gas inlet. Then, this gas flows along the surface of the wafer 2 whose temperature is uniformly controlled to form a silicon epitaxial growth film on the surface of the wafer.

The epitaxially grown film thus obtained is uniform and has extremely good crystallinity. That is, the susceptor and the wafer are heated to almost the same temperature, the gas reaches the wafer surface with a desired concentration distribution, and when the wafer 2 is rotated, a uniform growth rate can be obtained over the entire surface of the wafer 2. .

Although the CVD apparatus has been described in the above embodiment, it can be applied to other thin film deposition apparatus such as sputtering, etching apparatus such as reactive ion etching, or wafer heating control in a diffusion furnace. There is no end.

Further, although the heating using the infrared lamp has been described in the above embodiment, the present invention is not limited to this.
It is also applicable to resistance heating, high frequency heating, etc.

[0045]

As described above, according to the present invention, highly accurate and uniform temperature control can be performed.

[Brief description of drawings]

FIG. 1 is a diagram showing a control circuit according to an embodiment of the present invention.

FIG. 2 is a diagram showing the control rate of each heating unit in each FB.

FIG. 3 is a flowchart showing an outline of the overall operation of the control circuit of the embodiment of the present invention.

FIG. 4 is a flowchart showing an atmospheric temperature adjusting process.

FIG. 5 is a flow chart showing an impact degree measuring process.

FIG. 6 is a flowchart showing a load adjusting process.

FIG. 7 is a diagram showing a device configuration of an embodiment of the present invention.

FIG. 8 is a diagram showing a temperature measuring unit of the present invention.

FIG. 9 is a diagram showing a temperature measuring unit of the present invention.

FIG. 10 is a diagram showing a control circuit of a conventional example.

FIG. 11 is a diagram showing the control rate of each heating unit in each FB of the conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Reactor 2 Wafer 3 Susceptor 4 Motor 5 Heating means 6 Temperature measuring part 7 Load adjusting part 8 Load part 9 Controlled amount calculating part 701 Atmosphere temperature adjusting part 702 Influence measure part 703 Influence measure command part 704 Load learning part

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Tsuyoshi Yamada 197-17-105 Minami Toyota, Hiratsuka City, Kanagawa Prefecture (72) Inventor Shinji Marutani 726-5-401 Yamashita, Hiratsuka City, Kanagawa Prefecture

Claims (1)

[Claims] 1. A rotatable susceptor on which a substrate to be processed is mounted, a heating unit including a plurality of heating units for heating the substrate to be processed mounted on the susceptor to a desired temperature, Temperature measuring means having a plurality of temperature measuring parts for measuring temperatures at a plurality of points in the vicinity of the processing substrate, and from the measurement result of the temperature measuring means, measure the degree of influence of each heating part on each temperature measuring part. Influence degree measuring means to determine the load according to the output of the influence degree measuring means, calculate the control amount from these loads for each heating section, the measurement obtained from each temperature measuring section of the temperature measuring means A heat treatment apparatus comprising: a control unit that feedback-controls each heating unit so that the value becomes a target value.