JP2005136022A - Substrate processing apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a substrate processing apparatus capable of performing constant temperature control with high accuracy both when the temperature is rising and settled without enhancing the regulation revolving power of a DA converter. <P>SOLUTION: In the substrate processing apparatus comprising a means for heating a substrate by receiving power supply, a means for measuring the temperature of the substrate, a power regulator for regulating power being supplied to the heating means, and a control means for delivering a control signal to the power regulator based on a temperature measurement signal from the temperature measuring means, a plurality of power regulators are provided in parallel. Furthermore, at least one integrator which is fewer than the power regulators is provided and at least one of the plurality of power regulators is provided with a control signal from the control means through the integrator. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a substrate processing apparatus, and in particular, in the heat source control system, when there is a large difference in required power at the time of temperature rise and temperature stabilization, large power can be supplied at the time of temperature rise and fine at temperature stabilization. The present invention relates to a substrate processing apparatus that enables easy control.

  As an example of a conventional substrate processing apparatus, an RTP (Rapid Thermal Process) apparatus, which is one of heat treatment apparatuses used in a semiconductor manufacturing process, will be described as an example. As a feature of the RTP apparatus, a lamp is used as a heat source, and the wafer can be rapidly heated (for example, heated at 1000 ° C. for several tens of seconds) in a short time. The temperature control system measures the temperature of the wafer and feedback-controls a lamp as a heating means using a power regulator (SCR).

  FIG. 8 is a diagram illustrating an example of the control block. As shown in the figure, the wafer 1 is supported by a quartz susceptor 3 in a heat treatment chamber 2 and is heated by receiving an infrared ray 4 a by a lamp 4. The temperature of the wafer 1 is detected by a temperature measuring element 5 such as a thermocouple or an optical thermometer, converted into a temperature signal by a temperature measuring device 6, and fed back to a PID controller 7a of the controller 7. The PID controller 7a performs feedback control of the power from the power source 9 supplied to the lamp 4 by adjusting the SCR 8 so that the set value 7b matches the measured temperature.

  In the above configuration, the heat treatment chamber 2 is provided with various components made of quartz or the like, in addition to the susceptor 3. When the heat treatment process is performed, the infrared rays emitted from the lamp 4 are irradiated not only on the wafer 1 but also on the peripheral components. Therefore, when the wafer 1 is to be heated, the peripheral parts are also heated at the same time. By the way, the RTP apparatus is characterized in that rapid heating can be performed. When the temperature rises, it is necessary to supply a large amount of energy to the wafer 1 in a short time, and it is necessary to flow a large current through the lamp 4. For this reason, a large-capacity SCR 8 is used. At the time of temperature rise, high accuracy in power control is not required.

  However, when the temperature is stable, highly accurate temperature control with a small deviation from the set value 7b is required. In order to increase the accuracy of temperature control, it is necessary to finely control the lamp power (current), and accordingly, it is necessary to finely adjust (control) the SCR 8. When the accuracy of temperature control is obtained, the output resolution of the controller 7 becomes a problem. As a control signal to the SCR 8, a control signal such as 4 to 20 mA, 0 to 5 V or the like is usually used. As shown in FIG. 9, this control signal is output by DA-converting the result of PID calculation by the controller 7 by a DA (digital-analog) converter 7c. The DA conversion resolution of the controller 7 is determined by the performance of the DA converter 7c. Here, as an example, the conventional problem will be described on the assumption that the resolution of the DA converter 7c is 1/4000 and an SCR having a maximum current of 60A is used for rapid temperature rise.

  Since the control signal to the SCR 8 cannot be controlled below the resolution of the DA converter, in this case, 60A / 4000 = 0.15A. That is, in this control system, the maximum current can be controlled in units of 60 A / 0.015 A. However, in actuality, since the temperature of the wafer 1 changes only with a slight change in the lamp output, there is a demand for control with a system of 0.006 A or less of 0.01% or less.

  In the PID calculation, even if the calculation is fine up to 0.01%, the control accuracy becomes rough due to the limit of the DA converter 7c. As a result, there is a problem that temperature hunting does not fit when the temperature is stable.

Therefore, it is conceivable to use a small-capacity SCR with a maximum current of 24 A or less (0.006 A or less × 4000 resolution) in order to control with a resolution of 0.006 A or less, but this does not satisfy the temperature increase rate in terms of performance. .
In the above, an accuracy of 0.006 A unit is required as an example, but in order to further improve temperature controllability, control of 0.001 A unit or the like is also required.

  As one solution to this problem, there is a method in which the resolution of the DA converter 7c is reduced to 1/10000 or more. However, in the solution in which the resolution of the DA converter 7c is increased, the control accuracy is further improved. There is a possibility of not being able to follow when required. In addition, it is conceivable that the large-capacity SCR is switched and used as the SCR for temperature rising, and the small-capacity SCR is switched and used as the SCR for temperature stabilization. In this method, the control system is suddenly switched during PID control. There is a problem that disturbance of control occurs.

  The present invention provides a substrate processing apparatus capable of performing constant and highly accurate temperature control both at the time of temperature increase and at the time of temperature stabilization without increasing the adjustment resolution of the DA converter and without decreasing the temperature increase rate. The purpose is that.

  In order to solve the above-described problems, a substrate processing apparatus according to the present invention includes a heating unit that heats a substrate by receiving power supply, a temperature measurement unit that measures the temperature of the substrate, and power supplied to the heating unit. In a substrate processing apparatus, comprising: a power regulator (SCR) provided for adjusting the power; and a control means (controller) for outputting a control signal to the power regulator based on a temperature measurement signal from the temperature measurement means. A plurality of the power regulators are provided in parallel, and at least one integrator less than the number of the power regulators is provided, and at least one of the plurality of power regulators is controlled by the integrator. The control signal from the means is input.

  In the embodiment, the SCR has one SCR (small capacity SCR) for accurately controlling the temperature when the temperature is stable. The SCR has at least one SCR (large capacity SCR) for biasing the small capacity SCR. Further, the controller as the control means is connected to the same number of DA converters that perform output as the SCR.

  Further, the integrator is provided only on the input side of the large-capacity SCR. Further, a differentiator can be provided. In this case, the differentiator can be provided only on the input side of the large-capacity SCR. Further, the integrator and the differentiator can be provided in parallel. Furthermore, the integrator can be provided with a dead zone. The heating means is provided in one or one set (one zone) on the output side of the small-capacity SCR and the large-capacity SCR, and is controlled by the combined power of the small-capacity SCR and the large-capacity SCR. .

  As described above in detail, according to the present invention, it is possible to perform temperature control with a constant and high accuracy at the time of temperature increase and at the time of temperature stabilization without increasing the adjustment resolution of the DA converter, without decreasing the temperature increase rate. The substrate processing apparatus which can be provided can be provided.

  Embodiments of the present invention will be described below with reference to the drawings.

<Embodiment 1>
FIG. 1 is a functional block diagram showing a temperature control configuration of the substrate processing apparatus according to the first embodiment. The overall configuration of the substrate processing apparatus is the same as that shown in FIG. 8, and a description thereof is omitted here.

  In the first embodiment, the SCR 8-1 that directly inputs the PID calculation output via the DA converter 7c-1 is provided, the integrator 11 that integrates the PID calculation output is provided, and the output of the integrator 11 is DA converted. An SCR 8-2 to be input via the device 7c-2 is provided. That is, two SCRs 8-1 and 8-2 having a maximum current of 20 A are used as SCRs for controlling the lamp current. The manipulated variable (MV) of the PID calculation result is DA converted and output to the SCR 8-1. At the same time, the PID calculation result (MV) is input to the integrator 11. The output MV (I) of the integrator 11 is DA converted and output to the SCR2. The supply current (power) to the lamp is a combined current (power) of SCR1 + SCR2.

The operation will be described below.
First, an SCR with a maximum current of 20 A is used to ensure control accuracy when the temperature is stable. The maximum capacity of the SCR is determined based on a capacity and a standard that can ensure control accuracy. On the other hand, with one SCR with a maximum current of 20A, even if an attempt is made to output a PID calculation result of 100% or more at the time of temperature rise, there is a problem that the lamp current cannot actually flow at the limit of the SCR, and this satisfies the temperature rise performance. I can't. Therefore, by providing the SCR 8-2 in parallel with the SCR 8-1 and outputting the output MV (I) of the integrator 11 to the SCR 8-2, the two SCRs 8-1, 8 are raised during the temperature rise. −2 is set to an output state close to the maximum, and when the temperature is stable, it can be finely controlled by one SCR 8-1. Thus, by efficiently using the two sets of SCRs, the temperature rise performance and the accuracy of temperature stability control are satisfied.

As shown in FIG. 2, MV (I) integrates the deviation of MV-50% with 50% as a reference value (note that FIG. 2 shows the relationship between outputs to two SCRs. , Does not indicate actual measurements). By outputting this MV (I) to the SCR 8-2, the SCR 8-1 is biased. As a result, the PID calculation result MV becomes smaller and can be operated within the control range of the PID controller 7a. Therefore, temperature control can be performed without reducing control accuracy. That is, as shown in FIG. 3, the output range of the control system can be controlled in units of maximum current of 40 A / 0.005 A.
The output of the integrator 11 is set to zero as a lower limit, and the integrator 11 is configured so as not to output a negative value.

<Embodiment 2>
FIG. 4 is a functional block diagram showing a temperature control configuration of the substrate processing apparatus according to the second embodiment. In the second embodiment, a case will be described in which a higher lamp current (electric power) is required than when the first embodiment is used at the time of temperature rise, and higher accuracy is required when the temperature is stable.

  In the present embodiment, an SCR 8-3 having a maximum current of 10A and an SCR 8-4 having a maximum current of 60A are used. Further, the integrator for calculating the output to the SCR 8-4 is the integrator 12 with a dead zone in order to prevent the phase advance and the control from becoming unstable. As shown in FIG. 5, the integrator with dead band 12 has an upper limit value and a lower limit value set from the outside. When MV <lower limit value, [lower limit value-MV] is satisfied, and MV> upper limit value is satisfied. At time, [MV-upper limit value] is integrated and the result is MV (I). The integrator may perform an integration operation with a coefficient such as an I constant of PID calculation. For example, the integration is performed so that the I constant is zero in the dead zone and the I constant is a predetermined value outside the dead zone. You may make it perform operation | movement.

  The operation will be described below with reference to FIGS. 5 and 6. When a large amount of electric power is required at the time of temperature rise, MV is integrated from the point where MV exceeds the dead band upper limit, and MV (I) is increased, and SCR8− 3 is biased. Since this MV (I) is connected to the SCR of 60A, the MV (I) can behave 6 times larger than that of the SCR 8-3. At the time of temperature rise requiring a large amount of power, the output of the SCR 8-4 increases and a large lamp current can flow.

  Next, when the temperature becomes stable, the MV decreases from the point where the dead zone lower limit is exceeded, the output of the SCR 8-4 decreases, and finally only the SCR 8-3 is controlled. As a result, the resolution of the SCR 8-3 can be controlled. In other words, the output range of the control system can be controlled in units of the maximum current of 70 A / 0.0025 A.

<Third embodiment>
FIG. 7 is a functional block diagram showing a temperature control configuration of the substrate processing apparatus according to the third embodiment.
In the third embodiment, in addition to the configuration shown in the second embodiment, a differentiator 14 for differentiating the output of the MV is further provided, and this output value is added to the output of the integrator 13 with the dead band to thereby convert the DA converter 7c- 2 is entered.

  In this configuration, in order to improve the response to changes in MV, by adding a differential value of MV, the supply power is increased more quickly and the temperature increase rate is improved. That is, when the MV changes greatly, the reaction is slow only with the integration amount, but by providing the differentiator 13, the output of the SCR 8-4 can change quickly according to the change amount of MV when the MV changes greatly. become.

It is a functional block diagram which shows the structure by Embodiment 1 of this invention. It is a figure which shows the relationship between MV and MV (I). FIG. 3 is a diagram illustrating an operation of the first embodiment. 6 is a functional block diagram illustrating a configuration of a second embodiment. FIG. It is a figure which shows operation | movement of an integrator with a dead zone. FIG. 10 is a diagram illustrating the operation of the second embodiment. FIG. 10 is a functional block diagram illustrating a third embodiment. It is a functional block diagram which shows the control system in the conventional substrate processing apparatus. It is a block diagram which shows the function of a controller.

Explanation of symbols

  1 wafer, 2 heat treatment chamber, 4 lamps, 5 temperature measuring element, 6 temperature measuring device, 7 controller, 7a PID controller, 7c, 7c-1, 7c-2, DA converter, 8, 8-1, 8- 2,8-3,8-4 SCR, 9 power supply, 11 integrator, 12 dead zone integrator, 13 differentiator.

Claims (1)

Heating means for heating the substrate in response to power supply, temperature measuring means for measuring the temperature of the substrate, a power regulator provided for adjusting the power supplied to the heating means, and the temperature measuring means A substrate processing apparatus comprising control means for outputting a control signal to the power regulator based on a temperature measurement signal from
A plurality of power regulators are provided in parallel, and at least one integrator less than the number of power regulators is provided, and at least one of the plurality of power regulators is connected to the control means via the integrator. A substrate processing apparatus, wherein a control signal from is input.

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