JP2013008727A - Driving device for passive element and substrate heating device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a driving device for a passive element having satisfactory responsiveness and small power loss, and a substrate heating device using the driving device.SOLUTION: In a driving device, a DC power supply section 41 has an intermediate terminal 412 having intermediate potential between a high-voltage terminal 411 and a low-voltage terminal 413. In a parallel circuit of a passive element 21 and a voltage smoothing capacitor 312, one end is connected between the high-voltage terminal 411 and the intermediate terminal 413, and the other end is connected to the intermediate terminal 412 via a flywheel element 311 and a snubber circuit 313. A current detecting section 315 and a switching section 314 are connected in series between a connecting point of the flywheel element 311 and the snubber circuit 313 and the low-voltage terminal 413. An intermediate voltage between the high-voltage terminal 411 and the intermediate terminal 412 is set to a value smaller than a threshold voltage at which a passive element 21 is turned ON, and a current control section 32 controls the switching section 314 such that the passive element 21 is turned ON by a DC voltage added to the intermediate voltage.

Description

  The present invention relates to a technique for adjusting the output of a passive element such as an LED (Light Emitting Diode) by pulse width modulation (PWM).

  In the manufacture of semiconductor devices, there are various heat treatments for heating a semiconductor wafer (hereinafter referred to as a wafer) that is a substrate. Among them, a device using an LED (light emitting diode) that can increase and decrease the temperature at a high speed and emit a wavelength corresponding to the absorption wavelength of silicon, which is the material of the wafer, has been proposed.

  The applicant has developed a heat source using an LED array configured by connecting, for example, 100 to 200 LEDs in series in an annealing apparatus (substrate heating apparatus) that performs an annealing process after ion implantation. . In this technology, a plurality of LED arrays are provided in the heating section, which is a heat source, and by adjusting the amount of power supplied to each LED array, the amount of LED light is adjusted to achieve temperature rise and fall at the desired timing. (Patent Document 1)

Here, as one of the methods for adjusting the output of the LED, there is a method of adjusting the light emission amount by controlling the amount of power supplied to the LED, which is a passive element, by a pulse width modulation (hereinafter referred to as PWM) method. On the other hand, the LED has a voltage-current characteristic in which a current corresponding to the voltage starts flowing when a voltage equal to or higher than the threshold voltage (V _f ) is applied, but an LED array in which 100 or more LEDs are connected in series. In some cases, the threshold voltage value at which current begins to flow may increase to several hundred volts.

  Since the LED array having a large threshold voltage becomes a non-linear control system to which a simple Ohm's law cannot be applied, PWM control for adjusting the average output by repeatedly supplying and stopping power in a short time is performed on the LED array. When applied to an array, the controllability in the temperature rising / falling operation is degraded. In addition, a switching element (FET: Field Effect Transistor) having a high withstand voltage that can withstand the operation of turning on / off high voltage power including a threshold voltage is required, resulting in an increase in switching loss.

  Here, in Patent Document 2, in an LED illumination device including a transistor (semiconductor switch element) that switches an LED for illumination, it is detected whether the LED is in a non-energized state, and according to the state. A technique is described in which controllability when dimming to low illuminance is improved and power loss is reduced by adjusting the power input to the LED. However, this technique is a technique for improving the decrease in responsiveness and power loss caused by switching control of transistors, and a technique for solving the problems caused by the voltage-current characteristics of the LED array described above is described. Absent.

JP 2009-253242 A: Paragraphs 0032 to 0034, 0044, FIGS. JP 2009-266855 A: claim 1, paragraphs 0021-0024, FIGS.

  The present invention has been made under such a background, and an object of the present invention is to provide a drive device for a passive element with good response and low power loss, and a substrate heating device using the drive device.

A passive element driving apparatus according to the present invention includes a DC power supply unit having an intermediate terminal that is an intermediate potential between a high voltage terminal and a low voltage terminal;
A parallel circuit comprising a passive element and a voltage smoothing capacitor, one end of which is connected to the high voltage terminal;
A flywheel element connected to the other end of the parallel circuit;
A snubber circuit connected between the flywheel element and the intermediate terminal;
A series circuit composed of a current detection unit and a switching unit, connected between the connection point of the flywheel element and the snubber circuit and the low voltage terminal,
A current control unit that controls switching of the switching unit based on a deviation between a current command value and a current detection value detected by the current detection unit;
The intermediate voltage between the high voltage terminal and the intermediate terminal is set to a value smaller than a threshold voltage at which the passive element is turned on,
The passive element is turned on by adding a DC voltage controlled by a switching action of the switching unit to the intermediate voltage.

The passive element drive device may have the following characteristics.
(A) The passive element is a series circuit of a plurality of LEDs.
(B) The switching unit and the snubber circuit are switching elements, and synchronous rectification is performed to reverse the on / off state of the switching element of the switching unit and the switching element of the snubber circuit.

Further, a substrate heating apparatus according to another invention includes a processing container for storing a substrate,
A heating unit provided with a passive element for heating the substrate in the processing container by releasing energy corresponding to the supplied power;
A drive device for any one of the passive elements described above,
The substrate is heated by turning on the passive element by the driving device.

  The present invention applies an intermediate voltage smaller than a threshold voltage at which the passive element is turned on to the passive element, and further adds a DC voltage controlled by the switching action of the switching unit to the intermediate element. The current flows through the terminal and is turned on. As a result, since the change width of the voltage added using the switching unit is reduced, the switching loss accompanying the on / off operation can be reduced. In addition, since the pressure resistance required for the switching unit is reduced, it is possible to reduce the size of the equipment constituting the switching unit, and to reduce power loss in the unit.

It is a vertical side view of the annealing apparatus to which the LED driver concerning embodiment is applied. It is a top view which shows the heating part of the said annealing apparatus. It is explanatory drawing which shows the connection state of LED in the said LED array. It is explanatory drawing which shows the voltage-current characteristic of a LED array. It is explanatory drawing which shows the transient response of a voltage and an electric current when carrying out PWM control of the LED array. It is a circuit diagram which shows the 1st structural example of the drive device of a LED array. It is a circuit diagram which shows the 2nd structural example of the drive device of a LED array. It is a circuit diagram which shows the structure of the drive device concerning a comparative example. It is explanatory drawing which shows the time-dependent change of the temperature of switching FET. It is explanatory drawing which shows the power consumption efficiency according to a drive device. It is explanatory drawing which shows the power loss according to a drive device.

  A configuration example of an annealing apparatus 1 that is a substrate heating apparatus to which an LED array driving apparatus according to an embodiment of the present invention is applied and that anneals a wafer W having impurities implanted on the surface will be briefly described.

  The annealing apparatus 1 includes a processing container 11 formed in a flat cylindrical shape, and a cooling member 12a fitted in the opening so as to close the circular openings formed on the upper surface side and the lower surface side of the processing container 11. , 12b form a processing space 10 in which an annealing process is performed.

  On the side wall surface of the processing container 11, a loading / unloading port 111 for loading / unloading the wafer W and a gate valve 112 for opening / closing the loading / unloading port 111 are provided. A gas supply line 113 for supplying an inert gas such as nitrogen gas or argon gas into the processing space 10 is connected to the ceiling surface of the processing container 11, while the processing container 11 is connected to the bottom surface side of the processing container 11. An exhaust line 114 for exhausting the space 10 is connected. The exhaust line 114 is connected to an unillustrated exhaust means, and the pressure of the processing space 10 during the annealing process is maintained at a predetermined pressure within a range of 100 to 10,000 Pa, for example.

  In the processing space 10, for example, three support arms 13 (only two are shown in FIG. 1) provided with support pins 131 that support the wafer W from the lower surface side are provided. The wafer W can be held via these support pins 131. Each support arm 13 can be moved up and down by a lift mechanism (not shown), and the wafer W is transferred by crossing the support pins 131 in the vertical direction with an external wafer transfer mechanism, or a height position for holding the wafer W. Can be adjusted.

  Concave portions 121 are formed on the lower surface or upper surface of the cooling members 12 a and 12 b facing the upper and lower surfaces of the wafer W held by the support arm 13. A heating unit 2 serving as a heat source for the annealing process is formed in the recess 121, and an LED module 22 including a large number of LEDs 21 that are passive elements of the present embodiment is disposed in the heating unit 2. .

  As shown in FIG. 2, the LED module 22 of this example has a configuration in which a large number of LEDs 21 are arranged on the plate surface of a hexagonal support substrate 221 (the description of the LEDs 21 is omitted in FIG. 2). The plurality of LED modules 22 are arranged in the recesses 121 of the cooling members 12a and 12b so that the upper and lower surfaces of the wafer W are uniformly heated.

  Each LED module 22 has several series lines of about 100 to 200 LEDs 21. The wavelength of light emitted from these LEDs 21 is, for example, in the range of ultraviolet light to near infrared light, and preferably in the range of 0.36 to 1.0 μm. Examples of the material that emits light in the range of 0.36 to 1.0 μm include compound semiconductors based on GaN, GaAs, GaP, and the like. Among these, the LED 21 made of a GaAs-based material having a radiation wavelength in the vicinity of 850 to 970 nm, which has a high absorption rate particularly in a silicon wafer W used as a heating target, is more preferable.

  The LED module 22 is attached to the cooling members 12a and 12b so that the back surface side of the support substrate 221 is in contact with the cooling surfaces of the cooling members 12a and 12b. In addition, a light transmission plate 122 made of, for example, quartz is attached to the recesses 121 of the cooling members 12a and 12b so as to cover the LED module 22 from the surface side facing the wafer W. Therefore, the light emitted from the LED array 23 of the LED module 22 passes through the light transmission plate 122 and reaches the wafer W.

  Further, the space surrounded by the recesses 121 of the cooling members 12a and 12b and the light transmission plate 122 is a reduced-pressure atmosphere like the processing space 10, and the pressure difference between the upper and lower surfaces of each light transmission plate 122 is reduced. It is small. Thereby, it is possible to make the light transmission plate 122 thinner than in the case where the inside of the recess 121 is at atmospheric pressure, and light absorption in the light transmission plate 122 is suppressed.

  A cooling medium flow path 123 is formed in the cooling members 12a and 12b with which the support substrate 221 of the LED module 22 comes into contact. The cooling members 12a and 12b can be cooled to 0 ° C. or lower, for example, about −50 ° C. by flowing through the flow path 123. In FIG. 1, 124 is a refrigerant supply line, and 125 is a refrigerant discharge line.

The electrical configuration of the LED module 22 provided in the annealing apparatus 1 whose schematic configuration has been described above, the DC power supply 41 that supplies power to the LED module 22, and the LED driver 31 is described with reference to FIGS. explain.
Each LED module 22 shown in FIGS. 1 and 2 is provided with an LED array 23 composed of a series circuit in which 100 to 200 LEDs 21 are connected in series, as shown in FIG. 3, for example. Each LED module 22 may be provided with a plurality of LED arrays 23, and these LED arrays 23 may be connected in parallel to a DC power supply unit 41 and an LED driver 31 described below. Since the operation of the DC power supply unit 41 and the LED driver 31 does not change except that is changed, a case where one LED array 23 is driven will be described below.

As shown in FIG. 4, in the LED array 23 in which a large number of LEDs 21 are connected in series, the threshold voltage V _f of the entire LED array 23 until the current starts to flow is several hundred volts (in FIG. 4). In the example, 270V). Therefore, in the output control using PWM before applying the present invention, the voltage including this threshold voltage is turned on / off to the LED array 23.

  In general, an LED driver using PWM control is provided with a current smoothing coil, and the current is turned on / off behind a voltage on / off operation as shown in FIG. At this time, the switching loss in the LED array 23 is the product of the current value and the voltage value during the period when the current rises and the voltage drops, and the current value and the voltage value during the period when the current falls and the voltage rises. It is represented by the product of

  For this reason, if the voltage value applied by switching becomes high, the said switching loss will also become large. In addition, when a high voltage is applied, an FET or the like having a high withstand voltage is required as a switching element. However, since such an FET has a high on-resistance, a loss of power consumption also increases. In addition to this, an FET with high withstand voltage has a long ON / OFF switching time and a long period during which the switching loss shown in FIG. 5 is caused. Therefore, the switching loss also increases in this respect.

  Therefore, the DC power supply unit 41 and the LED driver 31 of the present embodiment always apply an intermediate voltage smaller than the threshold voltage shown in FIG. 4 to the LED 21, and add a voltage for PWM control to the intermediate voltage. Thus, the LED 21 is turned on. Hereinafter, the configuration of the DC power supply unit 41, the LED driver 31, and the current control unit 32 will be described with reference to FIG. The DC power supply unit 41, the LED driver 31, and the current control unit 32 constitute a drive device for the LED array 23 (LED 21) according to the present embodiment.

  As shown in FIG. 6, the DC power supply unit 41 of this example includes a high voltage terminal 411, a low voltage terminal 413, and an intermediate terminal 412 that is an intermediate potential between these terminals. The DC power supply unit 41 includes, for example, a known rectifier circuit that converts an alternating current supplied from a three-phase power supply into a direct current by PWM rectification. On the other hand, the LED array 23 forms a parallel circuit with a current smoothing capacitor 312, and the parallel circuit is connected to the high voltage terminal 411 of the DC power supply unit 41 at one end side in the forward direction and the upstream side of the LED 21. .

On the other hand, the other end side (forward direction, downstream side of the LED 21) of the parallel circuit is connected to the intermediate terminal 412 of the DC power supply unit 41 via a flywheel coil 311 for current smoothing and a snubber diode 313 forming a snubber circuit. ing. The potential difference (intermediate voltage) between the high voltage terminal 411 and the intermediate terminal 412 is a value smaller than the threshold voltage (voltage that turns on when the current starts to flow through the LED array 23) _Vf shown in FIG. It is set to 200V. This intermediate voltage is constantly applied to the parallel circuit (LED array 23 and capacitor 312). By setting the intermediate voltage to a value of, for example, 60 to 95%, more preferably 80 to 95% of the threshold value, the output control of the LED array 23 can be alleviated and the switching loss can be reduced. Get higher.

  In addition, a series circuit including a Hall IC 315 forming a current detection unit and a switching FET 314 serving as a switching unit between a connection point of the flywheel coil 311 and the snubber diode 313 and a low voltage terminal 413 of the DC power supply unit 41. Is provided. For example, a DC voltage of 200 V is applied between the low voltage terminal 413 and the intermediate terminal 412. Reference numerals 42 and 43 shown in FIG. 6 are voltage smoothing capacitors on the DC power supply 41 side.

  When the switching FET 314 is turned off, a circuit of the high voltage terminal 411 → the LED array 23 → the flywheel coil 311 → the snubber diode 313 → the intermediate terminal 412 is formed, and only the intermediate voltage is applied to the LED array 23. On the other hand, when the switching FET 314 is turned on, a circuit of the high voltage terminal 411 → the LED array 23 → the flywheel coil 311 → the switching FET 314 → the low voltage terminal 413 is formed. The voltage is added. Then, by changing the on / off interval of the switching FET 314, the voltage applied to the LED 21 can be controlled by changing the average voltage added to the intermediate voltage.

  The current value flowing toward the low voltage terminal 413 is detected by the Hall IC 315 and output as a voltage value corresponding to the current value, and then amplified by the differential amplifier 316 and converted into a balanced signal. The V / F converter 317 converts the voltage value into a frequency signal and then differentially outputs it to the current control unit 32 via the line driver 318.

  The frequency signal received by the line driver 321 in the current control unit 32 is counted by the microcomputer 322 and converted into a detected value of the current flowing through the line detected by the Hall IC 315. The microcomputer 322 compares a current command value from the device control unit 5 described later with a current detection value, and sends a control signal to the FET driver 319 to increase or decrease the pulse width for turning on the switching FET 314 in a direction to eliminate the deviation. Output toward. This control signal transmission / reception is also differentially output via the line drivers 321 and 318.

  The FET driver 319 changes the duty ratio of the time during which the switching FET 314 is turned on based on the control signal from the microcomputer 322, and changes the average DC voltage added to the above-described intermediate power.

  In this example, the capacitor 312, flywheel coil 311, snubber diode 313, Hall IC 315, switching FET 314, differential amplifier 316, V / F converter 317, line driver 318, FET driver 319 among the electrical configurations shown in FIG. Are provided on a common substrate to constitute the LED driver 31. As shown in FIG. 1, the LED driver 31 is provided between each LED module 22 of the heating unit 2 and a DC power supply unit 41 that supplies power to the LED module 22.

  On the other hand, the current control unit 32 including the line driver 321 that transmits and receives signals to and from the microcomputer 322 and the LED driver 31 illustrated in FIG. 6 is separate from the LED driver 31 and is separated from the LED driver 31. In position (FIG. 1). The current control unit 32 can acquire a current detection value and output a control signal of the switching FET 314 with a plurality of, for example, four LED drivers 31, and as a result, a plurality of LED modules. 22 output controls can be performed. The current control unit 32 constitutes a current control unit of the drive device according to the embodiment. In FIG. 1, a plurality of current control units 32 are shown collectively.

  As described above, from the LED driver 31, the current value is converted into a frequency signal and output, and the current signal is calculated after time integration of the frequency signal by the microcomputer 322 on the current control unit 32 side. This configuration is resistant to noise generated by the on / off operation of the switching FET 314. In addition, by performing signal transmission / reception between the LED driver 31 and the current control unit 32 in a differential manner, even when the current control unit 32 is disposed at a position away from the LED driver 31, highly reliable signal transmission / reception is possible. it can. As a result, the DC power supply unit 41 can be disposed in the immediate vicinity of the LED driver 31 to shorten the power transmission distance and supply power with a small number of wires. On the other hand, since only signal transmission is performed with the current control unit 32, it is only necessary to connect to the LED driver 31 using a thin signal line even from a distant position. Has improved.

  The annealing apparatus 1 having the configuration described above includes an apparatus control unit 5 that performs overall control of the entire apparatus. The apparatus control unit 5 is composed of a computer having a CPU and a storage unit (not shown). A program in which a group of steps (commands) for control related to processing time and the like is assembled is recorded. This program is stored in a storage medium such as a hard disk, a compact disk, a magnetic optical disk, or a memory card, and installed in the computer therefrom.

  In particular, when adjusting the output of the LED array 23 using the current control unit 32 and the LED driver 31, the apparatus control unit 5 detects a temperature detection value from a temperature detection unit (not shown) that detects the temperature of the wafer W arranged in the processing space 10. A function for outputting the power command value to each current control unit 32 so as to adjust the output of the LED array 23 in a direction to eliminate the deviation by comparing the set temperature of the annealing process with the temperature detection value. I have.

The operation of the annealing apparatus 1 having the above configuration will be described. The gate valve 112 of the processing container 11 is opened, and an external wafer transfer mechanism is entered from the loading / unloading port 111 to load the wafer W into the processing space 10. When the wafer W is placed on the support pins 131, the wafer transfer mechanism is retracted and the holding height of the wafer W is adjusted. Subsequently, the gate valve 112 is closed to make the inside of the processing container 11 sealed, and the inside of the processing container 11 is exhausted from the exhaust line 114, while an inert gas is introduced from the gas supply line 113, and the inside of the processing container 11 (processing The pressure in the space 10) is adjusted to a predetermined pressure within a range of 100 to 10,000 Pa, for example.
On the other hand, in the cooling members 12a and 12b, the refrigerant is passed through the refrigerant flow path 123, and the LED 21 of the LED module 22 is cooled to a temperature of 0 ° C. or lower, preferably −50 ° C. or lower.

  Then, power supply from each DC power supply unit 41 is started, and the LED driver 31 is operated to adjust the output of the LED array 23. At this time, as described with reference to FIGS. 4 and 6, an intermediate voltage (for example, 200 V) is constantly applied to the LED array 23 between the high voltage terminal 411 and the intermediate terminal 412. Based on the power command value from the microcomputer 322, the DC voltage between the intermediate terminal 412 and the low voltage terminal 413 is adjusted by PWM and added to the intermediate voltage, so that the LED array 23 is turned on and the output is adjusted. Is done.

At this time, the voltage controlled by the PWM (PWM control voltage shown in FIG. 4) is smaller than the voltage when the intermediate voltage is not applied (the sum of the intermediate voltage and the PWM control voltage shown in FIG. 4). Nonlinearity at the time of output adjustment of the LED array 23 is suppressed, and controllability is improved. Further, as a result of the voltage switching at the switching FET 314 being reduced, the voltage value (voltage value V _DS shown in FIG. 5) turned on / off by the PWM is reduced, and the switching loss can be reduced.

  Further, since the voltage value turned on / off by the switching FET 314 is reduced, the withstand voltage required for the switching FET 314 can be lowered. As a result, an FET having a low on-resistance and a short switching time can be adopted, and switching loss can be reduced from this viewpoint.

  The output of the LED array 23 is adjusted by such drive control, and the light emitted from the LED modules 22 provided in the upper and lower heating units 2 passes through the light transmission plate 122 and reaches the wafer W, and the wafer It is absorbed by W and raises its temperature. As a result, the wafer W is heated up to a target temperature (for example, 1100 ° C.) in a short time of about 1 to 10 seconds, and is implanted in the previous process by maintaining the temperature for a short time of about 1 to 10 seconds. A process of combining impurities such as boron and phosphorus with silicon is performed.

When the preset time has elapsed, the power supply to the LED array 23 is stopped, and the emission of light from the LEDs 21 is stopped, whereby the heating of the wafer W is stopped. The wafer W is rapidly cooled by the inert gas flowing in the processing space 10, and the annealing process is completed. After cooling the wafer W, the exhaust from the exhaust line 114 is stopped, the inside of the processing space 10 is returned to the atmospheric pressure, the wafer W is unloaded in an operation reverse to that during loading, and a series of operations is completed.
On the other hand, the LED module 22 that is in contact with the cooling members 12a and 12b is cooled by the refrigerant flowing in the refrigerant flow path 123, and waits until the next wafer W is carried in while suppressing a decrease in the amount of light emission accompanying the temperature rise. .

  According to the driving device (DC power supply unit 41, LED driver 31, current control unit 32) of the LED array 23 according to the present embodiment, there are the following effects. An intermediate voltage smaller than a threshold voltage at which the LED 21 of the LED array 23 is turned on is applied to the LED 21, and a DC voltage PWM-controlled by the switching action of the switching FET 314 is added to the intermediate voltage to add current to the LED 21. Flows and the output is adjusted. As a result, the change width of the voltage added by the PWM control using the switching FET 314 is smaller than that in the case where the intermediate voltage is not applied, so that the switching loss accompanying the on / off operation can be reduced. In addition, since the withstand voltage required for the switching FET 314 is reduced, the switching FET 314 can be downsized, and power loss in the part can be reduced.

  Here, the configuration of the driving device of the LED array 23 is not limited to the example shown in FIG. If an operation of constantly applying an intermediate voltage smaller than the threshold voltage of the LED array 23 and adding a DC voltage controlled by PWM to the intermediate voltage to turn on the LED array 23 is obtained, the configuration Can be changed as appropriate. For example, FIG. 7 shows an example in which a snubber FET 313 a is provided as a switching element in a snubber circuit provided between the high voltage terminal 411 and the intermediate terminal 412. 7, the same components as those shown in FIG. 6 are denoted by the same reference numerals as those in FIG.

  When the snubber FET 313a constitutes a snubber circuit, the FET driver 319 has a synchronous rectification function. When the switching FET 314 as a switching element is in an on state, the snubber FET 313a is in an off state, and when the switching FET 314 is in an off state. Switching control is performed to turn on the snubber FET 313a. Here, the switching elements constituting the switching unit and the snubber circuit are not limited to the case of being constituted by FETs (switching FETs 314 and snubber FETs 313a), and for example, bipolar transistors may be used.

  Further, the passive element drive device (the DC power supply unit 41, the LED driver 31, and the current control unit 32) shown in FIG. 6 and FIG. 7 is not limited to the application to drive control of the LED array 23 (LED 21). Absent. For example, the magnetron is known to exhibit the same voltage-current characteristics as the example shown in FIG. 4, and the present invention can improve the controllability and reduce the switching loss even in the drive control. it can. For example, the present invention can be applied to a substrate heating apparatus in which the magnetron is provided in a heating unit for irradiating a coating liquid containing moisture applied to the wafer W with microwaves and heating the coating liquid. In this case, the “passive element” described in the claims includes a passive device that is driven by being supplied with electric power.

(Experiment 1)
Electric power was supplied to the LED array 23 using the driving device of the present invention that adds a DC voltage adjusted by PWM to the intermediate voltage and a driving device that does not apply the intermediate voltage, and the temperature change of the switching FET 314 was examined.

A. Experimental conditions
(Example 1-1)
A driving device (a DC power supply unit 41, an LED driver 31, and a current control unit 32) using a snubber diode 313 as the snubber circuit shown in FIG. 6 is used to supply the LED array 23 with an average voltage of 160V and 400mA, and a switching FET 314. The temperature change of was measured. The intermediate voltage was 200 V, the PWM control voltage was 200 V, the pulse period of PWM control was 10 μm seconds, and the duty ratio (PWM%) was 80%. The withstand voltage capability of the switching FET 314 is 300V.
(Example 1-2)
Using the driving device using the snubber FET 313a as the snubber circuit shown in FIG. 7, power was supplied to the LED array 23 under the same conditions as in Example 1-1, and the temperature change of the switching FET 314 was measured. The withstand voltage capability of the switching FET 314 is 300V.
(Comparative Example 1-1)
Using a drive device that does not apply an intermediate voltage shown in FIG. 8, power was supplied to the LED array 23 under the same conditions as in Example 1-1, and the temperature change of the switching FET 314 was measured. In the driving apparatus of FIG. 8, the snubber circuit is a capacitor 312 and a shunt resistor 315a is used for current detection. The withstand voltage capability of the switching FET 314 is 600V.
(Comparative Example 1-2)
The temperature of the switching FET 314 was measured under the same conditions as in (Comparative Example 1-1) except that the snubber FET 313a was used as the snubber circuit. The withstand voltage capability of the switching FET 314 is 300V.

B. Experimental result
FIG. 9 shows changes with time in the temperature of the switching FET 314 in each example and comparative example. In FIG. 9, Example 1-1 is indicated by a broken line, Example 1-2 is indicated by a solid line, Comparative Example 1-1 is indicated by a two-dot chain line, and Comparative Example 1-2 is indicated by a one-dot chain line.

  According to the results shown in FIG. 9, the temperature rise width of the switching FET 314 in Examples 1-1 and 1-2 is smaller than the temperature rise width of the switching FET 314 in Comparative Examples 1-1 and 1-2. . It can be evaluated that this is because the voltage applied to the switching FET 314 is reduced and the switching loss is reduced due to the use of the switching FET 314 having a low withstand voltage. Further, comparing the case where the snubber diode 313 is used as the snubber circuit with the case where the snubber FET 313a is used, the temperature increase width of the switching FET 314 is smaller in the case where the snubber FET 313a is used in both the example and the comparative example.

(Experiment 2)
In the drive experiment of the LED array 23 in Example 1-1 and Comparative Example 1-1, the duty ratio (PWM%) of PWM was changed, and the power use efficiency and the power loss were calculated.

A. Experimental conditions (Example 2)
Using the drive device shown in FIG. 6, the PWM duty ratio was changed within the range of 0 to 100% under the same conditions as in Example 1-1.
(Comparative Example 2)
Using the drive device shown in FIG. 8, the PWM duty ratio was changed within the range of 0 to 100% under the same conditions as in (Comparative Example 1-1).

B. Experimental result
In the experimental results of Example 2 and Comparative Example 2, FIG. 10 shows a change in power use efficiency with respect to the duty ratio, and FIG. 11 shows a change in power loss. 10 and 11, the results of Example 2 are plotted with white circles, and the results of Comparative Example 2 are plotted with black circles.

  In the range where the duty ratio shown in FIG. 10 is about 0 to 30%, the power usage efficiency of Example 2 is smaller than that of Time Comparative Example 2, but in the range beyond this, Example 2 is more power efficient. The use efficiency is higher than that of Comparative Example 2. As shown in FIG. 11, there is no significant difference in power loss between Example 2 and Comparative Example 2 in the range where the duty ratio is low, but in the range where the duty ratio exceeds 60%, the driving shown in FIG. The difference in power loss between the device (Example 2) and the drive device (Comparative Example 2) shown in FIG. In the annealing apparatus 1 or the like that heats the wafer W to a high temperature in a short time, the PWM duty ratio tends to increase. Therefore, it can be said that the driving apparatus of the present embodiment is suitable for such processing.

W Wafer 1 Annealing device 21 LED
22 LED module 23 LED array 31 LED driver 311 Flywheel coil 312 Capacitor 313 Snubber diode 313a Snubber FET
314 Switching FET
315 Hall IC
319 FET driver 32 Current control unit 322 Microcomputer 41 DC power supply unit 411 High voltage terminal 412 Intermediate terminal 413 Low voltage terminal 5 Device control unit

Claims (4)

A direct current power supply unit having an intermediate terminal which is an intermediate potential between the high voltage terminal and the low voltage terminal;
A parallel circuit comprising a passive element and a voltage smoothing capacitor, one end of which is connected to the high voltage terminal;
A flywheel element connected to the other end of the parallel circuit;
A snubber circuit connected between the flywheel element and the intermediate terminal;
A series circuit composed of a current detection unit and a switching unit, connected between the connection point of the flywheel element and the snubber circuit and the low voltage terminal,
A current control unit that controls switching of the switching unit based on a deviation between a current command value and a current detection value detected by the current detection unit;
The intermediate voltage between the high voltage terminal and the intermediate terminal is set to a value smaller than a threshold voltage at which the passive element is turned on,
The passive element driving device according to claim 1, wherein a DC voltage controlled by a switching action of the switching unit is added to the intermediate voltage to be turned on.   2. The passive element driving apparatus according to claim 1, wherein the passive element is a series circuit of a plurality of LEDs.   The switching unit and the snubber circuit are switching elements, and synchronous rectification is performed to invert the ON / OFF state of the switching element of the switching unit and the switching element of the snubber circuit. Passive device drive device. A processing container for containing a substrate;
A heating unit provided with a passive element for heating the substrate in the processing container by releasing energy corresponding to the supplied power;
A passive element drive device according to any one of claims 1 to 3,
A substrate heating apparatus, wherein a substrate is heated by turning on a passive element by the driving device.

Images