JP2003086527A - Heat-treatment apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heat-treatment apparatus capable of shifting from open- loop control to feedback control with appropriate timing. SOLUTION: The heat-treatment apparatus shifts to feedback control when the following three conditions C1-C3 are satisfied in an open loop control section, namely the condition 1: a substrate temperature measurement value is equal to or higher than a first setting value (FB control start reference temperature), the condition C2: an elapse time from the start of heating is equal to or longer than a second setting time (timer value), the condition C3: a substrate temperature change rate measurement value is equal to or larger than a third setting value (reference temperature change rate) that is determined as a positive, specific value. Additionally, preferably the same value is used in the heat treatments of a plurality of substrates within the same lot as each setting 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 for heat treatment of a semiconductor substrate, a glass substrate for a liquid crystal display device, a glass substrate for a photomask, a substrate for an optical disk, etc. (hereinafter referred to as "substrate"), and more particularly to a heat treatment device. The present invention relates to a control technique for heat treatment of a device.

[0002]

2. Description of the Related Art Conventionally, in a substrate manufacturing process,
Various heat treatments are performed. As a heat treatment device for performing heat treatment on a substrate, for example, a light irradiation type heat treatment device for heating the substrate by light irradiation (so-called lamp annealing) is used.

When measuring the temperature of the substrate in such a light irradiation type heat treatment apparatus, a radiation thermometer (pyrometer) for non-contact temperature measurement is often used. This radiation thermometer measures the radiation intensity of light amplified by the multiple reflection effect between the substrate and the reflection plate, and determines the temperature from the radiation intensity (light amount).

Such a radiation thermometer has a measurement lower limit temperature (for example, 400 ° C.) in principle. The radiation thermometer cannot show an accurate temperature in a temperature range smaller than the lower limit measurement temperature. In such a low temperature state, the temperature measured by the radiation thermometer is different from the actual temperature, so it is not appropriate to perform feedback control using the temperature measured by the radiation thermometer.

Therefore, usually, in the initial stage of heating, open loop control (more specifically, constant power heating control for continuously applying a constant amount of heat to the substrate by supplying a constant power to the lamp) is performed, and thereafter, After shifting to the measurement temperature range of the radiation thermometer, feedback control using the temperature measurement value by the radiation thermometer is performed.

By the way, such a radiation thermometer is arranged on the opposite side of the lamp, which is the heating light source, with the substrate in-between, in the above heat treatment apparatus.
The substrate and the radiation thermometer are arranged in this order from the upper side. Thus, by placing the substrate between the lamp and the radiation thermometer, direct light from the lamp is prevented from entering the radiation thermometer.

However, it is known that the light absorption characteristics of the substrate have temperature dependence. Due to the temperature dependence of the light absorption characteristics, the substrate that was semitransparent at room temperature gradually becomes opaque as the temperature rises, and becomes about 600 ° C.
With the above, it becomes a gray body.

According to this temperature dependence, the temperature measured by the radiation thermometer shows a value different from the actual temperature. This will be described below.

An optical filter is provided on the entrance surface of this radiation thermometer, and a wavelength range (for example, about 0.8 μm to about 1.0) that overlaps with the basic absorption band of the substrate (silicon wafer) is provided.
The radiation intensity of the transmitted light is measured by selectively transmitting (μm) light, but usually, in order to increase the S / N ratio of the radiation thermometer, or due to manufacturing factors, etc. The transmission range of the optical filter is set relatively wide.

In this case, when the light emitted from the lamp irradiates a substrate having a relatively low temperature (for example, 600 ° C. or lower), the irradiating light transmits through the substrate and further through the optical filter. To do. Therefore, more light enters the probe (radiation intensity measuring unit) of the radiation thermometer. As a result, the temperature measured by the radiation thermometer rises due to the influence of the lamp direct light transmitted through this substrate. The measured value of the radiation temperature is larger than the actual temperature.

On the other hand, when the light emitted from the lamp irradiates a substrate having a relatively high temperature (for example, 600 ° C. or higher), the direct light is blocked by the substrate, and an appropriate amount of light is emitted by the radiation thermometer. Is incident on the probe (radiation intensity measurement unit) of. As a result, the measured value of the radiation temperature is close to the actual temperature (ideally, it matches).

More specifically, the situation of rapidly heating a substrate at room temperature with a lamp will be considered with reference to FIG. At first, the substrate W is semi-transparent and a large amount of light is incident on the radiation thermometer, so that the temperature measured by the radiation thermometer is higher than the actual substrate temperature. Along with this, the measured value TA of the radiation thermometer rises to the peak Pk.
After that, as the actual temperature of the substrate rises, the transmissivity characteristic of the substrate changes and the amount of transmitted light from the substrate decreases, so that the temperature measured value by the radiation thermometer falls once. Then, when the heating is further continued, the temperature measured value by the radiation thermometer changes from decreasing to increasing and then further increases in accordance with the actual temperature increase of the substrate.

[0013]

As described above, in the heat treatment in the heat treatment apparatus, the open loop control at the initial stage is changed to the feedback control at the next stage. Then, the transition from such open loop control to feedback control is performed during the period in which open loop control is being performed.
The elapsed time from the start of heating reaches the predetermined set value tm0, and the measured value by the radiation thermometer shows the predetermined set temperature Tm0.
It is performed when the temperature reaches F (hereinafter also referred to as “feedback control start reference temperature”) or higher. The timer set value tm0 is set by predicting the time until the temperature measured by the radiation thermometer exceeds the peak Pk (FIG. 6) and then rises again.

This is to ensure that the temperature measured by the radiation thermometer starts to rise again after it has exceeded the peak, and the radiation thermometer is conditioned again, on condition that the timer reaches a predetermined set value. It is ensured that the temperature has sufficiently risen by setting the condition that the measured temperature according to 1 reaches the feedback control start reference temperature. That is, the control performance in the feedback control is secured by starting the feedback control from the state where such conditions are satisfied.

However, assuming that the timer set value tm
If 0 is not set properly, the following problems occur.

First, when the timer set value tm0 is set as a value larger than an appropriate value, as shown in FIG. 7, the feedback control start reference temperature T at which the feedback control should be started during open loop control.
Even if the substrate temperature TW (or TA) exceeds F,
The feedback control cannot be started until the elapsed time from the start of heating reaches the timer set value tm0. Therefore, there is a problem in that the feedback control start time is delayed and the period in which the feedback control temperature is made to follow the target value SV is shortened. The substrate temperature TW represents the actual substrate temperature, and the temperature TA represents the temperature measured by the radiation thermometer.

On the other hand, when the timer set value tm0 is set to a value smaller than an appropriate value, there is a problem that a hunting phenomenon occurs after shifting to the feedback control. This hunting phenomenon is the following phenomenon.

As shown in FIG. 8, the timer set value tm0
Is set to a value smaller than an appropriate value, the substrate temperature TW has not risen so much at the time when the elapsed time from the start of heating reaches the timer set value tm0. The measured temperature TA may be equal to or higher than the feedback control start reference temperature TF, and the feedback control is started at this point. At this time, until the measured temperature TA once drops and then starts to rise again (in other words, until the actual substrate temperature TW rises), the deviation from the target value SV becomes large, so a large amount of power is supplied and heat is generated. It is given in excess.

In particular, when the timer setting value tm0 is not set to a value large enough to ensure that the temperature TA measured by the radiation thermometer exceeds the peak Pk and then starts to rise again, the timer setting value tm0 is extended for a longer time. A large amount of power is applied, and the substrate is rapidly heated. Then, when the substrate temperature suddenly rises due to the application of a large amount of electric power and exceeds the target value SV, the control output by the feedback control suddenly becomes smaller this time. Further, if the substrate temperature greatly drops in response to this, a slightly larger control output is given in order to raise the substrate temperature this time. As described above, a hunting phenomenon accompanied by a relatively large vibration occurs in the temperature control. Such a hunting phenomenon is not preferable for control.

As described above, if the timer set value tm0 is not properly set, the above problem occurs.

Further, it is more difficult to set the timer set value tm0 to an appropriate value and start the feedback control at an appropriate timing due to the following circumstances.

That is, when processing a plurality of substrates included in one lot, which is one processing unit, the temperature state in the heat treatment apparatus when heating the first (or third) substrate and the subsequent temperature This is a situation in which the temperature state in the heat treatment apparatus when heating the substrate (for example, the tenth substrate) is different. This is because the temperature of each part in the heat treatment apparatus at the start of heating gradually becomes higher as the heat treatment of the substrate is continuously repeated.

When the heat treatment is continuously performed on a plurality of substrates, if the heat treatment is performed at the same set value, the situation as shown in FIGS. 7 and 8 will occur. In consideration of such circumstances, the timer value is set to be relatively long when heating the first substrate, while the timer value is set to be relatively short when heating the tenth substrate. Required to do.

However, with respect to a plurality of substrates included in one lot, the timer set value (timer value) is set to an appropriate value in consideration of the difference in the thermal state of each substrate at the time of processing. There is a problem that it is difficult to start the feedback control at the timing.

Therefore, in view of the above problems, it is an object of the present invention to provide a heat treatment apparatus capable of shifting from open loop control to feedback control at an appropriate timing.

[0026]

In order to achieve the above-mentioned object, the invention of claim 1 is a heat treatment apparatus for heat-treating a substrate, which is a holding means for holding the substrate, and a substrate held by the holding means. A heating means for heating the substrate, a heating plate facing the substrate and arranged on the opposite side of the heating device with respect to the substrate, and a reflecting plate for reflecting heat radiation from the substrate; Radiation intensity measuring means arranged on the opposite side with respect to each other and receiving the heat radiation between the substrate and the reflecting plate to measure the radiation intensity, and the radiation intensity of the substrate based on the radiation intensity measured by the radiation intensity measuring means. Temperature calculating means for calculating a substrate temperature measurement value which is a temperature measurement value, and temperature change rate calculating means for calculating a substrate temperature change rate measurement value which is a measurement value of the substrate temperature change rate based on the substrate temperature measurement value. And the heating means Control means for controlling the heating operation according to the above, wherein the control means switches between an open loop control section for performing open loop control and a feedback control section for performing feedback control based on the substrate temperature measurement value in this order. When performing heating control on the substrate, in the open loop control section,
The substrate temperature measurement value is equal to or higher than a first set value, and
Open loop control provided that the elapsed time from the start of heating is equal to or greater than the second set value and the measured value of the substrate temperature change rate is equal to or greater than the third set value defined as a positive predetermined value. From the feedback control.

According to a second aspect of the present invention, in the heat treatment apparatus according to the first aspect of the present invention, the third set value is a positive value smaller than the target value of the substrate temperature change rate in the initial temperature rising stage of the feedback control section. It is characterized by being defined as a value.

According to a third aspect of the present invention, in the heat treatment apparatus according to the first aspect of the invention, the third set value is a positive value equal to or lower than a virtual maximum temperature rise rate due to a control output in an open loop control section. It is characterized by being defined.

According to a fourth aspect of the present invention, in the heat treatment apparatus according to the first aspect of the present invention, the third set value is set as a predetermined value of 5 ° C. or more per second and 20 ° C. or less per second. .

According to a fifth aspect of the present invention, in the heat treatment apparatus according to any one of the first to fourth aspects, as the third set value, the same value is set in the heat treatment of a plurality of substrates in the same lot. Is used.

According to a sixth aspect of the present invention, in the heat treatment apparatus according to any one of the first to fifth aspects, the second set value is set as a predetermined value of 2 seconds or more and 10 seconds or less. It is characterized by

According to a seventh aspect of the present invention, in the heat treatment apparatus according to any one of the first to fifth aspects, the second set value is equal to or longer than a time required to reach the peak temperature in the open loop control section. Further, it is characterized in that it is set as a predetermined value equal to or less than the time until the starting temperature of the feedback control is reached by the control output in the open loop control.

According to an eighth aspect of the present invention, in the heat treatment apparatus according to any one of the first to seventh aspects, as the second set value, the same value is set in the heat treatment of a plurality of substrates in the same lot. Is used.

According to a ninth aspect of the present invention, in the heat treatment apparatus according to any one of the first to eighth aspects, the first set value is the same value in the heat treatment of a plurality of substrates in the same lot. Is used.

[0035]

BEST MODE FOR CARRYING OUT THE INVENTION <1. Overall Structure of Heat Treatment Apparatus> FIG. 1 is a vertical sectional view showing an example of a heat treatment apparatus according to the present invention. The heat treatment apparatus 1 is a so-called lamp annealing apparatus, and mainly includes the furnace body 10, the lamp 20, and the quartz glass 3.
0, substrate holding / rotating unit 40, temperature measuring unit 50, control unit 6
0, a lamp power supply 80, and a motor driver 90. The furnace body 10 is a cylindrical furnace body having an upper portion as a reflector 110 and a lower portion as a housing 120, and a large number of cooling pipes 130 for cooling a refrigerant through the inside thereof are provided. Further, a substrate loading / unloading port E is provided on the side surface of the furnace body 10.
W is provided, and the substrate W is loaded and unloaded by an external transport device (not shown) during the heat treatment.

The lamps 20 correspond to "light sources" (or heat sources) and are provided in large numbers on the lower surface of the reflector 110 (only a part of the reference numeral is shown in FIG. 1). To do. The lamp 20 heats the substrate W held by the substrate holding / rotating unit 40 (described later). Here, a halogen lamp is used as the lamp 20.

The quartz glass 30 is provided below the lamp 20 and transmits radiant light due to its thermal radiation.

In the substrate holding / rotating section 40, a holding ring 410 for holding the peripheral portion of the substrate W over the entire circumference is supported by a cylindrical supporting leg 420, and the supporting leg 42 thereof.
A bearing 430 is provided at the lower end of 0 along the outer periphery thereof. The gear provided on the outer periphery of the bearing 430 is attached to the gear 44 of the rotation shaft of the substrate rotation motor 440.
1 are in mesh with each other, and the driving thereof causes the retaining ring 410.
Is rotatable about the vertical axis.

The temperature measuring unit 50 measures the radiant intensity (radiant energy) in consideration of multiple reflection of thermal radiation from the substrate W, and obtains the substrate temperature and the like based on the value (measured value) obtained by the measurement. , And sends those signals to the control unit 60.

The control unit 60 has a CPU and a memory therein, and sends a temperature control signal of the lamp 20 to the lamp power supply 80 and a drive signal to the motor driver 90 at a predetermined timing. The controller 60 controls the heating operation of the lamp 20 on the substrate W by sending a temperature control signal to the lamp 20.

The lamp power supply 80 receives a control command value S (specifically, a temperature control signal) from the control unit 60 and applies a voltage V corresponding thereto to the lamp 20.

The motor driver 90 receives a drive signal from the control unit 60 and supplies electric power corresponding to the drive signal to the substrate rotary motor 4
Supply to 40.

Further, the temperature measuring section 50 has a reflecting plate 510, a measuring unit 520 and a computing section 550. The reflection plate 510 is the substrate W held by the substrate holding / rotating unit 40.
Is arranged on the upper surface of the housing 120 so as to face the above and reflects heat radiation from the substrate W. The reflector 510 is arranged on the opposite side of the lamp 20 with the substrate W in between. Further, the reflecting plate 510 is provided with a cylindrical hole 510a penetrating therethrough. Furthermore, the hole 510
The measuring unit 520 is provided in the housing 120 below the a.
The casing 521 of the
The upper portion of 21 is in close contact with the inner surface of the hole 510a, and a cylindrical hollow portion CP is provided in the upper portion of the casing 521.

Further, the inner surface of the casing 521 has a reflectance improved by vapor-depositing a metal such as aluminum on the entire surface, and the inside of the casing 521 has the same cooling pipe 1 as that provided inside the housing 120.
30 are provided, and by these, the casing 521
It suppresses the internal temperature rise and improves the measurement accuracy of the substrate temperature.

A quartz glass plate 522 is provided at the upper end of the cavity CP, and an optical filter (hereinafter simply referred to as a filter) 523 is provided on the lower surface of the quartz glass plate 522.
Are closely attached. The filter 523 is formed by depositing a metal oxide such as T _i O ₂ on the entire lower surface of the quartz glass plate 522. The filter 523 has the property of transmitting only the radiation light in the wavelength range of a predetermined range near the measurement wavelength and reflecting the radiation light in the other wavelength bands almost completely. This allows
Since it is possible to minimize the penetration of radiated light into the casing 521 due to thermal radiation, it is difficult for the inside of the casing 521 and the probe 526 to be heated, and high measurement accuracy can be realized.

As described above, the substrate holding / rotating unit 40.
Since the supporting legs 420 of the
When holding the substrate W by the
A closed space is formed between and. Therefore, the heat radiation from the lamp 20 is prevented from directly or reflected by the inner surface of the housing 120 or the like and entering the hole 510a to reach the probe 526. This makes the measurement of the radiation intensity by the probe 526 accurate.

The probe 526 is arranged on the opposite side of the lamp 20 with the substrate W in between, and more specifically, it is provided inside the hole 510a. This probe 526 is configured by using a silicon photodiode as a measuring element, and radiates incident radiant light passing through the hole 510a into a voltage,
That is, it is converted into an electric signal representing the radiation intensity, and the calculation unit 55
0 (see FIG. 1). This probe 526 is a substrate W
Radiation intensity is measured by receiving heat radiation between the reflector 510 and the reflection plate 510. That is, in this embodiment, the probe 52
6 corresponds to the radiation intensity measuring means.

The calculation unit 550 has a CPU and a memory, and calculates the substrate temperature based on the radiation intensity of the substrate W detected by the probe 526.

By executing the processing program in the arithmetic unit 550, the functions of the temperature calculation unit TC and the temperature change rate calculation unit RC are realized by software. The temperature calculation unit TC has a function of calculating a substrate temperature measurement value that is a measurement value of the temperature of the substrate based on the radiation intensity measured by the probe 526 or the like, and the temperature change rate calculation unit RC includes the temperature calculation unit TC. It has a function of calculating a substrate temperature change rate measured value, which is a measured value of the temperature change rate of the substrate, based on the substrate temperature measured value calculated by.

By the way, in the heat treatment apparatus 1, when the rotary sector 524 is rotated by the motor 525 under the control of the motor driver 530, the transmitted and reflected states of radiated light due to thermal radiation alternate, and the effective reflectance differs. Toggle between two values. By utilizing this property, it is possible to measure the radiation intensity in multiple reflection and calculate the substrate temperature measurement value, which is the measurement value of the temperature of the substrate, based on the measured radiation intensity. Here, details such as the principle are omitted.

<2. Heating Operation of Heat Treatment Apparatus> Next, the heating operation of the heat treatment apparatus 1 will be described. The control of the heating operation is performed by the control unit 60.

FIG. 2 is a diagram showing changes over time in the target temperature of the substrate W and the temperature measured by the radiation thermometer of the substrate W in the heat treatment apparatus 1.

As shown in FIG. 2, this heating operation has an open loop control section A for performing open loop control and a feedback control section B for performing feedback control based on the measured value of the substrate temperature. Then, the open loop control section A and the feedback control section B are selectively switched and carried out in this order. Thereby, the heating control for the substrate W is performed.

At the start of heating, open loop control is performed. Specifically, as this open-loop control, constant-power heating is performed in which the lamp 20 is lit by using a constant power and a constant amount of heat is continuously applied. In this open loop control, for example, a constant value of a predetermined ratio (for example, 30% to 40%) of the rated maximum output of the lamp 20 is determined as the output value of the lamp 20 and heating is continued. This open loop control is performed until the next feedback control is performed. The transition condition from the open loop control to the feedback control will be described later in detail.

In the next feedback control section B, feedback control is performed in which the temperature of the substrate W follows the target value based on the measured temperature measured by the radiation thermometer. As this feedback control, P
ID calculation control or the like can be used.

In FIG. 2, the change with time of the target value in the feedback control section B is shown as a target curve SL. Note that, in FIG. 2, a change with time of the measured value of the temperature of the substrate W by the radiation thermometer is shown as a measured temperature curve ML.

Further, the target curve SL has an initial temperature raising stage B1 and a constant temperature holding stage B2.

Among them, the initial heating step B1 is a step of heating the substrate W to a constant temperature by rapid heating. Specifically, a temperature increase curve that rises from the temperature at the time of starting the feedback control to a constant temperature at a predetermined temperature increase rate (substrate temperature change rate) is set as the target curve SL.
The temperature rising rate in the initial temperature rising stage B1 is, for example, 20 ° C./second (20 ° C./second) to 150 ° C./second (1 / second).
50 ° C.), and a different value is set for each recipe that defines various conditions for each substrate W.

The constant temperature holding step B2 is a step of holding the temperature of the substrate W heated in the initial temperature rising step at a predetermined target temperature TH set for a predetermined period. Then, the heating is finished after the lapse of the certain period.

FIG. 3 is a flow chart showing the heating control including the transition operation from the open loop control to the feedback control. Each process will be described with reference to FIG.

As shown in FIG. 3, first, step S10.
At, the substrate (wafer) W is loaded into the heat treatment apparatus 1.

In the next step S20, the atmosphere gas inside the furnace body (chamber) 10 is replaced and the entrained outside air is purged.

Then, in step S30, open loop control, more specifically, constant power heating is started.

Then, in the open loop control section A (FIG. 2) in which this open loop control is performed, processing for checking the transition condition from the open loop control to the feedback control is performed (step S40). Specifically, (1) condition C1: the measured value of the substrate temperature is the first set value (hereinafter,
(Also referred to as "feedback control start reference temperature TF")
Above, (2) Condition C2: The elapsed time from the start of heating is equal to or more than the second set value (hereinafter, also referred to as "timer set value tm"), (3) Condition C3: Substrate temperature change rate It is checked whether or not all the three conditions, that the measured value is equal to or greater than the third set value (hereinafter, also referred to as “reference temperature change rate RT”), are met.
Then, when it is confirmed that all of these three conditions C1, C2, and C3 are met, the control shifts from open loop control to feedback control.

Here, as the first set value (feedback control start reference temperature), the same value may be used in the heat treatment of a plurality of substrates in the same lot which are subjected to the same treatment based on the same recipe. preferable. The same applies to the second set value (timer set value) tm and the third set value (reference temperature change rate) RT.
It is preferable that m and the third set value RT have the same value in the heat treatment of a plurality of substrates in the same lot. In this case, it is not necessary to set different values for each of the plurality of substrates in the same lot, which facilitates the setting.

As the first set value (feedback control start reference temperature) TF, a value larger than the measurement lower limit temperature TL (for example, 400 ° C.) of the radiation thermometer is set. The feedback control start reference temperature TF is set according to the recipe, and is set as an appropriate value such as 450 ° C. to 550 ° C., for example.

The second set value (timer set value) t
A predetermined value is set as m according to the recipe. The timer set value tm is defined as a predetermined value that is equal to or longer than the time until the peak temperature is reached in the open loop control section and equal to or less than the time until the feedback control start temperature is reached by the control output in the open loop control. Specifically, this timer set value tm
Can be set according to the recipe, for example, as a predetermined value of 2 seconds or more and 10 seconds or less.

Further, the third set value (reference temperature change rate)
A predetermined positive value is set as RT. Specific values are set according to the recipe. In addition, this reference temperature change rate RT
Is more preferably set as a predetermined value smaller than the target value of the substrate temperature change rate in the initial temperature raising step B1 of the feedback control section.

For example, the target value of the substrate temperature change rate in the initial temperature raising stage B1 of the feedback control section B is 20.
When it is set as ° C / sec, the reference temperature change rate RT can be set as 10 ° C / sec. Also,
When the target value of the substrate temperature change rate in the initial temperature raising stage B1 of the feedback control section is set to 50 ° C./second, the reference temperature change rate RT can be set to 30 ° C./second.

However, in any case, in order to allow the substrate temperature change rate to reach a predetermined reference temperature change rate RT during heating in the open loop control section A, the maximum temperature rise during constant power heating is performed. It is premised that the control output during constant power heating is set so that the rate exceeds each reference temperature change rate RT (10 ° C./sec or 30 ° C./sec). In other words, the reference temperature change rate RT is the maximum value of the temperature increase rate that is assumed to be achieved by the control output during constant power heating (in other words, the virtual maximum temperature increase due to the control output during constant power heating). Rate) will be set to a smaller value.

After that, these three conditions C1, C2,
When it is confirmed that all of C3 are complete, feedback control is started in step S50. Then, over a predetermined feedback control section B, feedback control based on the temperature measured by the radiation thermometer is performed, and the heating process is performed.

Here, the above three conditions C1, C2, C
The point that the transition can be performed at an appropriate timing by transitioning from the open loop control to the feedback control after confirming that all 3 have been completed will be described.

First, the feedback control start reference temperature T
F is the measurement lower limit temperature TL of the radiation thermometer (for example, 400
C.) is set to a predetermined value, and the feedback control is not started until the condition C1 that the substrate temperature measurement value is equal to or higher than the feedback control start reference temperature TF is satisfied, thereby reaching a predetermined temperature. After confirming that the feedback control is being performed, the feedback control can be started.

Further, the timer set value tm is set to a predetermined value (for example, about 2 seconds) longer than the time required to reach the peak temperature in the open loop control section,
By preventing the feedback control from being started until the condition C2 that the elapsed time from the start of heating is the timer set value tm or more is satisfied, it is possible to prevent the feedback control from being started in the initial heating stage before the peak Pk is reached. it can. Conversely, it is preferable that the timer set value tm is set as a value as small as possible among the values that are equal to or longer than the time required to reach the peak temperature in the open loop control section.

Furthermore, the third set value (reference temperature change rate)
RT is defined as at least a positive predetermined value,
If condition C3 is not complete, the other two conditions C
Even if 1 and C2 are complete, feedback control is not started. That is, when the measured value of the substrate temperature change rate is negative or zero, the feedback control is not started.

If the condition C3 is not taken into consideration, the feedback control will be started when the other conditions C1 and C2 are met. For example, as shown in FIG. 8 described above, the elapsed time from the start of heating is the timer set value tm.
When the temperature reaches the temperature, more specifically, the feedback control is started at the stage where the temperature TA measured by the radiation thermometer of the substrate W drops after exceeding the peak Pk. In this case, since there is a large difference between the measured temperature TA of the substrate W and the target temperature SV, the hunting phenomenon will occur as described above.

On the other hand, the condition C3 is also taken into consideration in this embodiment. That is, the feedback control is not started until the condition C3 is met, and the above three conditions C1,
After confirming that C2 and C3 have all been completed, the process proceeds to feedback control. Therefore, as shown in FIG.
When the measured temperature TA of the substrate W drops after exceeding the peak Pk, the feedback control is not started yet, and then the feedback control is started after the temperature TA starts to rise. That is, the feedback control is started after the actual temperature TW of the substrate W sufficiently rises. The substrate temperature TW represents the actual substrate temperature, and the temperature TA represents the temperature measured by the radiation thermometer.

Therefore, as described above, in the open loop control section A, even when the measured temperature TA of the substrate W by the radiation thermometer rises and then falls, it is appropriate to change from open loop control to feedback control. It is possible to determine the appropriate transition timing. Specifically, as described above, the feedback control is started after the actual temperature TW of the substrates W is sufficiently increased, so that the first one in the lot including the plurality of substrates W to be continuously processed is first. It is possible to effectively prevent the hunting phenomenon that tends to occur when the inside of the heat treatment apparatus is still cold, such as a sheet. In addition, when the heat treatment of the substrate is continuously repeated and the inside of the heat treatment apparatus is sufficiently warmed, for example, when heating the tenth substrate in the lot, the heat state is taken into consideration. Then, Fig. 5
As shown in, it is possible to shift to the feedback control at a relatively early time point after the timer set value tm has elapsed.

<3. Other> Reference temperature change rate RT
According to the recipe, it is preferable to set a relatively large value among predetermined values equal to or lower than the virtual maximum temperature increase rate by the control output during constant power heating. For example, the virtual maximum temperature rise rate due to the control output during constant power heating is 30 ° C.
In case of / sec, the reference temperature change rate RT can be set as 20 ° C / sec. In this case, the feedback control is not yet started at the time when the measured temperature TA of the substrate W drops after exceeding the peak Pk, and after that, the temperature TA starts to rise, and then a larger temperature rising rate (20 ° C./sec).
The feedback control will be started at the time of reaching. That is, since the feedback control can be started after the substrate temperature has risen sufficiently, the effect of preventing the occurrence of hunting is high.

Further, the reference temperature change rate RT is preferably set as a predetermined value of 5 ° C./second (5 ° C./second) or more and 20 ° C./second (20 ° C./second) or less. In this case, the virtual maximum heating rate in constant power heating is, for example, 20 ° C. /
Hunting can be effectively prevented as described above regardless of whether the temperature is in the range of seconds to 150 ° C./second. In particular, in the case of constant power heating, when the control output that makes the virtual maximum temperature rise rate 20 ° C./sec or less is not given (in other words, the virtual maximum temperature rise rate is always 20 ° C./second). In the case of being more than a second), such a value can be set as a general-purpose reference temperature change rate RT. In this case, not only can it be set as a parameter common to the heat treatment of the plurality of substrates W in the lot, but also the same value can be used for different recipes, so that the setting is easy.

[0081]

As described above, the claims 1 to 9 are as follows.
In the open loop control section, the substrate temperature measurement value is equal to or higher than the first set value, and
If the elapsed time from the start of heating is equal to or greater than the second set value and the measured value of the substrate temperature change rate is equal to or greater than the third set value defined as a positive predetermined value, the open loop control is performed. Since the control shifts to the feedback control, it is possible to shift from the open loop control to the feedback control at an appropriate timing.

In particular, according to the second aspect of the invention, the third set value is defined as a positive value smaller than the target value of the substrate temperature change rate in the initial temperature rising stage of the feedback control section. Therefore, it is possible to more reliably shift to the feedback control while preventing hunting.

Further, according to the third aspect of the invention, the third set value is determined as a positive value equal to or lower than the virtual maximum temperature increase rate by the control output in the open loop control section, so that it is more reliable. It is possible to shift to feedback control while preventing hunting.

Further, according to the invention of claim 5,
As the third set value, the same value is used in the heat treatment of a plurality of substrates in the same lot, so that the setting is easy.

According to the eighth aspect of the invention, since the same value is used as the second set value in the heat treatment of a plurality of substrates in the same lot, the setting is easy.

Further, according to the invention of claim 9,
As the first set value, the same value is used in the heat treatment of a plurality of substrates in the same lot, so that the setting is easy.

[Brief description of drawings]

FIG. 1 is a vertical sectional view showing a heat treatment apparatus 1 according to an embodiment of the present invention.

FIG. 2 is a diagram showing changes over time in the target temperature of the substrate W and the temperature measured by the radiation thermometer of the substrate W in the heat treatment apparatus 1.

FIG. 3 is a flowchart showing a heating control operation.

FIG. 4 is a diagram showing an example of a substrate temperature change in a heating operation.

FIG. 5 is a diagram showing another example of a change in substrate temperature during a heating operation.

FIG. 6 is a diagram illustrating a conventional technique.

FIG. 7 is a diagram illustrating a conventional technique.

FIG. 8 is a diagram illustrating a conventional technique.

[Explanation of symbols]

1 Heat treatment equipment 20 lamps 30 quartz glass 40 Substrate holding and rotating unit 50 Temperature measurement unit 510 reflector 520 Measuring unit 526 probe A open loop control section B Feedback control section B1 initial heating stage B2 constant temperature holding stage TC temperature calculator RC temperature change rate calculator TF Feedback control start reference temperature tm timer set value RT reference temperature change rate

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 4K056 AA09 CA18 FA01 FA12                 5H323 AA05 BB04 CA06 CB04 CB33                       CB42 CB44 DA01 FF01 GG15                       HH02 HH03 KK01 KK05 LL01                       LL02 LL19

Claims (9)

[Claims] 1. A heat treatment apparatus for heat-treating a substrate, comprising: holding means for holding the substrate; heating means for heating the substrate held by the holding means; and the heating means facing the substrate and the heating means. Located on the opposite side across the substrate, the reflector for reflecting the heat radiation from the substrate, and the heating means are placed on the opposite side across the substrate,
Radiation intensity measuring means for measuring radiation intensity by receiving thermal radiation between the substrate and the reflection plate, and a substrate temperature which is a measured value of the temperature of the substrate based on the radiation intensity measured by the radiation intensity measuring means. A temperature calculation means for calculating a measurement value; a temperature change rate calculation means for calculating a substrate temperature change rate measurement value which is a measurement value of the temperature change rate of the substrate based on the substrate temperature measurement value; and a heating operation by the heating means. And a control unit for controlling the open loop control section for performing open loop control, and a feedback control section for performing feedback control based on the substrate temperature measurement value in this order for the substrate. When performing heating control, in the open loop control section, the substrate temperature measurement value is equal to or higher than the first set value, and heating is started. Feedback from the open loop control on condition that the elapsed time is equal to or more than the second set value and the measured value of the substrate temperature change rate is equal to or more than the third set value defined as a positive predetermined value. A heat treatment apparatus characterized by shifting to control. 2. The heat treatment apparatus according to claim 1, wherein the third set value is defined as a positive value smaller than a target value of the substrate temperature change rate in the initial temperature rising stage of the feedback control section. A heat treatment apparatus characterized by the above. 3. The heat treatment apparatus according to claim 1, wherein the third set value is defined as a positive value equal to or lower than a virtual maximum temperature increase rate by a control output in an open loop control section. Characterizing heat treatment equipment. 4. The heat treatment apparatus according to claim 1, wherein the third set value is set as a predetermined value of 5 ° C. or more per second and 20 ° C. or less per second. 5. The heat treatment apparatus according to claim 1, wherein the same third set value is used in the heat treatment of a plurality of substrates in the same lot. Heat treatment equipment. 6. The heat treatment apparatus according to claim 1, wherein the second set value is set as a predetermined value of 2 seconds or more and 10 seconds or less. apparatus. 7. The heat treatment apparatus according to claim 1, wherein the second set value is at least a time until reaching a peak temperature in an open loop control section, and the open loop control is performed. The heat treatment apparatus is defined as a predetermined value that is equal to or less than the time until the feedback control start temperature is reached by the control output in. 8. The heat treatment apparatus according to claim 1, wherein the second set value uses the same value in the heat treatment of a plurality of substrates in the same lot. Heat treatment equipment. 9. The heat treatment apparatus according to claim 1, wherein the same first set value is used in the heat treatment of a plurality of substrates in the same lot. Heat treatment equipment.