JP2020122194A - Temperature control method for vapor deposition apparatus - Google Patents

Abstract

To provide a temperature control method for a vapor deposition apparatus, allowing for deposition of a high quality film having little variance.SOLUTION: The temperature control method for a vapor deposition apparatus 1 is provided in which a vapor phase raw material is supplied to a substrate W mounted on a substrate mount plate 5 while the substrate W is heated by a heater 6 with the temperature controlled using a thermocouple 7, and a thin film is thus deposited on the substrate W. The temperature control method includes the steps of: heating the heater 6 so that a temperature measured by the thermocouple 7 reaches a set temperature; measuring the temperature of the substrate mount plate 5 or the temperature of the substrate W mounted on the substrate mount plate 5 by an optical temperature sensor 9; calculating a difference between the set temperature and the temperature measured by the optical temperature sensor 9; adding a reference temperature difference to the difference to calculate a total correction value; and correcting the set temperature based upon the total correction value to perform the temperature control over the heater 6.SELECTED DRAWING: Figure 1

Description

The present invention relates to a temperature control method for a vapor phase growth apparatus.

Generally, a vapor phase growth apparatus rotatably provided in a film forming chamber, a substrate placing plate on which a substrate (wafer) is placed and provided on the susceptor, and a substrate placed through the substrate placing plate. And a heater for heating. In a vapor phase growth apparatus, a substrate placed on a substrate placing plate is heated by a heater, a vapor phase raw material is supplied to the substrate, and a thin film is deposited on the substrate to perform vapor phase growth.

By the way, in the vapor phase growth apparatus, it is important to set the surface temperature of the substrate to the same condition for each process in order to obtain the same quality (for example, refer to Patent Document 1 below). Therefore, the following two methods can be considered as the temperature control method.

One is a method in which a thermocouple is provided near the heater to measure the temperature, and feedback control is performed based on the measured value. The other is a method of measuring the substrate mounting plate temperature or the surface temperature of the substrate mounted on the substrate mounting plate with an optical temperature sensor and performing feedback control based on the measured value.

JP, 2014-194996, A

However, when performing feedback control by measuring with a thermocouple provided in the vicinity of the heater, there is a problem that the reproducibility for each process is not sufficient because the difference in the environment of the substrate cannot be reflected.

When operating the vapor phase growth apparatus, the surface temperature of the substrate is corrected by periodic temperature measurement. Specifically, the correction value is calculated so that the value of the temperature sensor that controls the heater (heating means) and the value of the temperature sensor that measures the surface temperature of the substrate approximately match, and the correction based on this correction value is performed. It is done by the control device. Further, the temperature condition of the film forming process is determined by the corrected temperature. However, in each process, the temperature further changes from the corrected value due to the environmental change in each process. Therefore, temperature correction for each process is desired.

When the surface temperature of the substrate is measured by an optical temperature sensor and feedback control is performed with respect to the temperature sensor that controls the heater (heating means), the substrate placed on the substrate mounting plate is constantly rotated by the rotation of the susceptor. You cannot measure the same point. Also, due to factors such as the strain of the substrate changing with temperature, stable measurement is difficult and the measured temperature changes significantly.

The present invention has been proposed in view of such conventional circumstances, and an object of the present invention is to provide a temperature control method for a vapor deposition apparatus capable of performing high-quality film formation with little variation. To do.

In order to achieve the above object, the present invention provides the following means.
[1] Gas phase for supplying a gas phase raw material to the substrate while heating the substrate mounted on the substrate mounting plate with a heater whose temperature is controlled using a thermocouple to deposit a thin film on the substrate A temperature control method for a growth apparatus, comprising:
Heating the heater so that the temperature measured by the thermocouple reaches a set temperature;
Measuring the temperature of the substrate mounting plate or the temperature of the substrate mounted on the substrate mounting plate by an optical temperature sensor,
Calculating a difference between the set temperature and the temperature measured by the optical temperature sensor;
Calculating a total correction value by adding a reference temperature difference to the difference;
A step of correcting the set temperature based on the comprehensive correction value and controlling the temperature of the heater.
[2] The temperature control method for a vapor phase growth apparatus according to [1], wherein the step of correcting the set temperature is performed a plurality of times during the same process.

As described above, according to the present invention, it is possible to provide a temperature control method for a vapor phase growth apparatus that enables high-quality film formation with less variation.

It is sectional drawing which shows the structure of the vapor phase growth apparatus which concerns on one Embodiment of this invention. It is a figure. 6 is a flowchart for explaining a method of determining a total correction value ΔT of the vapor phase growth apparatus shown in FIG. 1. 6 is a flowchart for explaining temperature control based on a total correction value ΔT of the vapor phase growth apparatus shown in FIG. 1.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
In the drawings used in the following description, in order to make each component easy to see, the scale of dimensions may be different depending on the component, and the dimensional ratio of each component may not be the same as the actual one. Absent.

(Vapor growth equipment)
First, as an embodiment of the present invention, a configuration of a vapor phase growth apparatus 1 shown in FIG. 1, for example, will be described. Note that FIG. 1 is a cross-sectional view showing the configuration of the vapor phase growth apparatus 1.

As shown in FIG. 1, the vapor phase growth apparatus 1 of the present embodiment rotates (revolves) through a substantially flat cylindrical film forming chamber 2 and a rotary shaft 3 penetrating the bottom surface of the film forming chamber 2. The disk-shaped susceptor 4, a plurality of substrate mounting plates 5 that are provided side by side in the circumferential direction (rotational direction) of the susceptor 4 and that rotate (rotate) while the substrate W is mounted, and the susceptor 4 A heater 6 arranged on the bottom surface side to heat the substrate W via the substrate mounting plate 5, a thermocouple 7 arranged near the heater 6 to measure the temperature of the heater 6, and an upper surface of the film forming chamber 2 An optical temperature sensor 9 for roughly measuring the temperature of the substrate mounting plate 5 or the temperature of the substrate W mounted on the substrate mounting plate 5 is provided via the light transmitting portion 8 provided.

The vapor phase growth apparatus 1 also includes a temperature setting unit 15 that sets the temperature of the heater 6, and a set temperature correction unit that performs temperature correction to the temperature set by the temperature setting unit 15 (hereinafter, referred to as “set temperature”). 10, a heater control unit 11 that controls the heating of the heater 6 based on the temperature measured by the thermocouple 7 so that the temperature is corrected, and the difference between the set temperature and the temperature measured by the optical temperature sensor 9. And a temperature correction value calculation unit 13 that corrects the set temperature based on the reference temperature difference in which the difference and a preset value are recorded in the recording unit 14.

In the vapor phase growth apparatus 1, while heating the substrate W placed on the substrate placing plate 5 by the heater 6, the vapor phase raw material is supplied to the substrate W to deposit a thin film on the substrate W, thereby performing the vapor phase growth. Is done.

(Temperature control method of vapor phase growth apparatus)
Next, a temperature control method of the vapor phase growth apparatus 1 to which the present invention is applied will be described with reference to FIG. Note that FIG. 2 is a flowchart for explaining a method of determining the total correction value ΔT of the vapor phase growth apparatus 1.

In the temperature control method for the vapor phase growth apparatus 1 according to the present embodiment, first, the total correction value ΔT is determined. Specifically, in step S1 shown in FIG. 2, the heating of the heater 6 is controlled by the heater control unit 11 so that the temperature measured by the thermocouple 7 becomes the set temperature T ₀ set by the temperature setting unit 15. To do.

Next, in step S2 shown in FIG. 2, the optical temperature sensor 9 measures the temperature of the substrate mounting plate 5 or the surface temperature of the substrate W mounted on the substrate mounting plate 5. Then, the measured value T ₁ of the temperature measured by the optical temperature sensor 9 is supplied to the difference calculation unit 12.

The temperature measurement by the optical temperature sensor 9 is always performed after the heating by the heater 6 is started. On the other hand, the measured value T _{1 of the} temperature supplied to the difference calculation unit 12 is not heated by the heater 6 after the heating by the heater 6 starts and the temperature measured by the thermocouple 7 reaches the set temperature T _0. It is a temperature measured after the control (stable control) for maintaining the set temperature T ₀ is started.

Next, in step S3 shown in FIG. 2, the difference calculator 12 calculates the difference between the set temperature T ₀ and the temperature (measured value T ₁ ) measured by the optical temperature sensor 9. That is, the difference calculator 12 calculates a difference value Δt (=T ₀ −T ₁ ) between the set temperature T ₀ and the measured value T _{1 of the} temperature measured by the optical temperature sensor 9. Then, the difference value Δt calculated by the difference calculation unit 12 is supplied to the temperature correction value calculation unit 13.

Next, in step S4 shown in FIG. 2, the temperature correction value calculation unit 13 calculates the total correction value ΔT (=Δt+StdΔ) by adding the previously stored reference temperature difference StdΔ to the difference (difference value Δt). To do.

Here, since the vapor phase growth apparatus 1 periodically performs temperature correction, the difference value Δt calculated in step S3 includes the reference temperature difference StdΔ used for correction in advance. In order to avoid the duplicated correction, it is necessary to delete this reference temperature difference. Therefore, the temperature correction value calculation unit 13 calculates the total correction value ΔT (=Δt+StdΔ) in consideration of the reference temperature difference StdΔ.

Next, temperature control based on the total correction value ΔT of the vapor phase growth apparatus 1 will be described with reference to FIG. It should be noted that FIG. 3 is a flowchart for explaining the temperature control based on the total correction value ΔT of the vapor phase growth apparatus 1.

The vapor phase growth has a film forming process in which the temperature is changed depending on the time axis from the time when the substrate W is carried in until the time when the substrate W is carried out. The basic environment of this one-time film forming process is regarded as the same. After unloading the substrate W, not only the conditions due to the newly loaded substrate W or the like are changed, but also the parts such as the heater 6 and the substrate mounting plate 5 in the film forming chamber 2 are replaced with new basics. Considered the environment.

Therefore, the set temperature for the dynamic temperature control in this one-time film forming process is set to "T100". Therefore, the set temperature T ₀ has the same value as the set temperature T100 at the time of temperature correction.

In the present invention, in one basic environment, after the total correction value ΔT at a certain set temperature T ₀ is determined, the correction for the set temperature T100 that is dynamically temperature controlled is executed. On the other hand, in one film forming process, a plurality of set temperatures T ₀ to be corrected may be provided, and the correction may be executed for each set temperature.

The present invention is characterized in that a correction value is determined at a typical control temperature in the basic environment and the correction value can be used during the same basic environment, that is, in one film forming process.

Specifically, first, in step S101 shown in FIG. 3, the set temperature correction unit 10 adds a total correction value ΔT to the set temperature T100 to calculate a corrected temperature T100′ by a correction execution command. However, if it is not necessary to perform the correction, T100' remains T100.

Next, in step S102 shown in FIG. 3, the set temperature correction unit 10 sets the corrected set temperature T100' to the set temperature T100.

Next, in step S103 shown in FIG. 3, the heater control unit 11 controls the heating of the heater 6 so that the temperature measured by the thermocouple 7 becomes the corrected set temperature T100'. By performing such control, the surface temperature of the substrate W measured by the optical temperature sensor 9 becomes T100.

This makes it possible to control the temperature of the substrate W with respect to the set temperature T100 with good reproducibility for each film forming process. Further, according to this control method, not only the change of the condition derived from the substrate W or the like but also the same basic condition when the parts such as the heater 6 and the substrate mounting plate 5 in the film forming chamber 2 are replaced. It is effective for improving temperature reproducibility in the environment.

Further, in the present embodiment, the steps of correcting the set temperature shown in FIGS. 2 and 3 described above may be performed a plurality of times during the same film forming process.

In this case, while the difference calculation unit 12 calculates the difference value Δt based on the temperature measurement value T ₁ constantly measured by the optical temperature sensor 9, when the difference value Δt exceeds a certain threshold value, the temperature The correction value calculation unit 13 obtains the total correction value ΔT, the set temperature correction unit 10 corrects the set temperature T100, and the heater control unit 11 controls the heating of the heater 6 based on the corrected set temperature T100′. May be.

On the other hand, the difference calculation unit 12 calculates the difference value Δt based on the temperature measurement value T ₁ that the optical temperature sensor 9 regularly measures, and the temperature correction value calculation unit 13 calculates the difference value Δt based on this difference value Δt. The total correction value ΔT may be calculated, the set temperature correction unit 10 may correct the set temperature T100, and the heater control unit 11 may control the heating of the heater 6 based on the corrected set temperature T100′.

As described above, in the temperature control method for the vapor phase growth apparatus 1 according to the present embodiment, the temperature control of the substrate W with respect to the set temperature T ₀ described above is performed with good reproducibility for each process, thereby achieving high quality with little variation. It is possible to form a film.

Hereinafter, the effects of the present invention will be made more apparent by examples. The present invention is not limited to the following examples, and can be implemented with appropriate changes without departing from the scope of the invention.

(Example)
In the embodiment, 10 wafers (substrates W) are mounted on the substrate mounting plate 5 by using the vapor phase growth apparatus 1, and a predetermined amount of nitrogen gas is allowed to flow into the film forming chamber 2 for setting. The temperature T ₀ was set to 1000° C., and heating by the heater 6 was performed. Then, after the temperature of the heater 6 measured by the thermocouple 7 reaches the set temperature T ₀ (1000° C.) for performing temperature correction, the surface temperature of the wafer is measured by the optical temperature sensor 9.

As a result, the average surface temperature of 10 wafers (measured value T ₁ ) was 1010°C. Therefore, the difference value Δt (=T ₀ −T ₁ ) between the set temperature T ₀ and the temperature (measured value T ₁ ) measured by the optical temperature sensor 9 was calculated to be −10° C.

At this time, the reference temperature difference StdΔ preset by the periodic temperature measurement was 3.4°C.

The measured value T ₁ (1010° C.) already includes the correction value of 3.4° C. Therefore, the total correction value ΔT (=Δt+StdΔ) obtained by adding the reference temperature difference StdΔ (3.4°C) to the difference value Δt (-10°C) described above is -6.6°C.

After the total correction value ΔT is determined, until the film formation is completed and the wafer is taken out, the total correction value ΔT (−6.6° C.) is used for the dynamic set temperature T100 in the vapor deposition process. Make a correction.

Subsequently, the set temperature T100 is changed according to the film forming process, and when the set temperature T100 is set to 750° C., the set temperature T100′ (=T100+ΔT) corrected in consideration of the total correction value ΔT is calculated.

Based on the total correction value ΔT, the temperature of the heater 6 was controlled by setting the corrected set temperature T100' to 743.4°C. After that, when the surface temperature of 10 wafers was measured by the optical temperature sensor 9, the average value of the corrected surface temperature of the wafer was 750° C.

After that, heating of the wafer was stopped, and after cooling to room temperature, all the wafers were exchanged for another newly prepared wafer. Then, such a process test was repeated 10 times. As a result, it was confirmed that the average value of the corrected surface temperature of the wafer in each process was within the range of 749°C to 751°C.

(Comparative example)
In the comparative example, using the vapor phase growth apparatus 1, 10 wafers (substrates W) are mounted on the substrate mounting plate 5, respectively, and a predetermined amount of nitrogen gas is allowed to flow into the film forming chamber 2 for setting. The temperature T ₀ was set to 750° C. and heating by the heater 6 was performed. Then, after the temperature of the heater 6 measured by the thermocouple 7 reached the set temperature T ₀ (750° C.), the surface temperature of the wafer was measured by the optical temperature sensor 9.

As a result, the average value of the surface temperatures of 10 wafers (measured value T ₁ ) was 748°C. After that, heating of the wafer was stopped, and after cooling to room temperature, all the wafers were exchanged for another newly prepared wafer. Then, such a process test was repeated 10 times. As a result, it was confirmed that the average value of the surface temperature of the wafer in each process was within the range of 747°C to 752°C.

From the above, it has been clarified that the temperature control of the wafer with respect to the set temperature can be performed with good reproducibility for each process in the example as compared with the comparative example.

DESCRIPTION OF SYMBOLS 1... Vapor growth apparatus 2... Film-forming chamber 4... Susceptor 5... Substrate installation plate 6... Heater 7... Thermocouple 9... Optical temperature sensor 10... Set temperature correction part 11... Heater control part 12... Difference calculation part 13... Temperature correction value calculation unit 14... Recording unit 15... Temperature setting unit W... Substrate

Claims (2)

A substrate mounted on a substrate mounting plate is heated by a heater whose temperature is controlled using a thermocouple, while supplying a vapor-phase raw material to the substrate to deposit a thin film on the substrate. A temperature control method,
Heating the heater so that the temperature measured by the thermocouple reaches a set temperature;
Measuring the temperature of the substrate mounting plate or the temperature of the substrate mounted on the substrate mounting plate by an optical temperature sensor,
Calculating a difference between the set temperature and the temperature measured by the optical temperature sensor;
Calculating a total correction value by adding a reference temperature difference to the difference;
A step of correcting the set temperature based on the comprehensive correction value and controlling the temperature of the heater. The temperature control method for a vapor phase growth apparatus according to claim 1, wherein the step of correcting the set temperature is performed a plurality of times during the same process.

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