JP2012226893A - Flash light discharge lamp lighting device, light irradiator, and method of hardening photo-curing material by using flash light discharge lamp lighting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress generation of distortion on a wafer at a light irradiation step of a semiconductor wafer and the like, and thereby to improve a yield in semiconductor chip manufacturing.SOLUTION: A flash light discharge lamp lighting device lights a flash light discharge lamp to harden a photo-curing material added to a substrate. The flash light discharge lamp lighting device has: a step-up charging circuit comprising a step-up circuit stepping up an input voltage and a power storage circuit charging an output of the step-up circuit; an initiation circuit performing dielectric breakdown of the flash light discharge lamp to introduce an energy from the power storage circuit to the flash light discharge lamp; and a controller controlling the step-up charging circuit and the initiation circuit to make the flash light discharge lamp perform successive lighting of a plurality of times. The controller is configured to apply an actual irradiation mode where the power storage circuit is charged with a relatively high energy to perform lighting after a weak irradiation mode where the power storage circuit is charged with a relatively low energy to perform lighting, in the successive lighting.

Description

  The present invention relates to a flash discharge lamp lighting device, a light irradiator, and a method of curing a photocurable material using the same, and relates to, for example, a flash discharge lamp lighting device used in a light irradiation process of a semiconductor wafer substrate in a semiconductor manufacturing process.

  Conventionally, in a semiconductor manufacturing process, in a process of separating a semiconductor wafer substrate called dicing into individual semiconductor chips, an ultraviolet curable tape (hereinafter referred to as “tape”) or a semiconductor wafer substrate to be attached to the semiconductor wafer substrate before the separation. An ultraviolet lamp has been used as a light source for ultraviolet irradiation for curing an ultraviolet curable coating (hereinafter referred to as “paint”) to be applied.

  However, considering the deformation of the semiconductor wafer substrate due to the radiant heat from the UV lamp and the irradiation time, a flash discharge lamp typified by a xenon lamp that can irradiate flash discharge light instead of the ultraviolet lamp in recent years. Has been adopted. This is because, compared to ultraviolet lamps, flash discharge lamps emit less heat when lit and can radiate high-intensity radiant light in a short time, so that tape or paint can be cured efficiently. is there.

  Patent Document 1 discloses a lighting device for lighting this flash discharge lamp. The lighting device charges the storage capacitor with a high voltage, and in a state where the charged high voltage is applied to the flash discharge lamp, by applying a high voltage pulse of several tens kV to the trigger wire close to the outside of the discharge lamp, The lamp is dielectrically broken, and the electric charge of the storage capacitor is discharged at once as the lamp current. The flash discharge lamp is usually an annular lamp corresponding to a circular semiconductor wafer, and the semiconductor wafer is illuminated almost uniformly by the flash discharge lamp.

Japanese Patent No. 4140279

  In recent years, it has been desired to increase the size (larger diameter) of a semiconductor wafer for the purpose of improving the efficiency of semiconductor manufacturing, and a φ450 mm wafer has been adopted instead of the conventional φ300 mm wafer. Since the area of the semiconductor wafer becomes large, light having a large energy may be irradiated by discharge. However, it has been found that the distortion of the wafer caused by light irradiation, which has hardly been a problem with a φ300 mm wafer, appears at a level that cannot be ignored in a φ450 mm wafer.

  When the tape or paint is cured in the above light irradiation step, the tape or paint shrinks slightly in the course of curing. As a result of this shrinkage, the chip in the semiconductor wafer is distorted. This is hardly a problem for a chip near the center of a circular semiconductor wafer, but the effect of shrinkage increases from the center toward the outside, and chip distortion becomes a problem. Therefore, this distortion hardly poses a problem in the case of a φ300 mm wafer, but in the case of a φ450 mm wafer, the influence is particularly large in a chip existing on the outer peripheral portion. If the amount of strain is large, the semiconductor chip becomes defective, which causes a problem that the yield in manufacturing the semiconductor chip is lowered.

  Therefore, an object of the present invention is to suppress generation of strain on a substrate due to contraction of the tape or paint when the tape or paint applied to the substrate to be irradiated is cured. In particular, it is an object to suppress the generation of strain on the wafer in the light irradiation process of the semiconductor wafer, thereby improving the yield in semiconductor chip manufacturing.

  A first aspect of the present invention is a flash discharge lamp lighting device for lighting a flash discharge lamp in order to cure a photocurable material attached to a substrate. The flash discharge lamp lighting device includes a booster circuit that boosts an input voltage and a booster charge circuit that includes a power storage circuit that charges the output of the booster circuit. The flash discharge lamp is dielectrically broken to input energy from the power storage circuit to the flash discharge lamp. And a control unit for controlling the boosting charging circuit and the starting circuit to cause the flash discharge lamp to perform a series of lightings a plurality of times. The control unit has a relatively low energy in the series of lightings. After the weak irradiation mode in which the power storage circuit is charged and turned on, the main irradiation mode in which the storage circuit is charged with the relatively high energy and turned on is applied.

  The second aspect of the present invention is a light irradiator including the flash discharge lamp lighting device and the flash discharge lamp according to the first aspect.

  A third aspect of the present invention is a method for curing a photo-curing material applied to a substrate, comprising a boosting circuit that boosts an input voltage and a boosting charging circuit comprising a storage circuit that charges the output of the boosting circuit, and a flash discharge lamp. A starting circuit for causing dielectric breakdown to input energy from the power storage circuit to the flash discharge lamp, and a control unit for controlling the boosting charging circuit and the starting circuit for causing the flash discharge lamp to perform a series of lighting operations a plurality of times. A flash discharge lamp lighting device is used. This method includes a weak irradiation stage in which a relatively low energy is charged in a storage circuit in a series of lighting, and a main irradiation stage in which a relatively high energy is charged in the storage circuit after the weak irradiation stage and is lit. Is provided.

  In the first and third aspects, the boosted value by the booster circuit in the weak irradiation mode (weak irradiation stage) may be lower than the boosted value in the main irradiation mode (main irradiation stage). In addition, the power storage circuit is configured with a plurality of power storage elements and a switch for switching the connection state of the plurality of power storage elements so that the combined capacity of the power storage elements in the weak irradiation mode is smaller than the combined capacity in the main irradiation mode. Good. Furthermore, between the weak irradiation mode and the main irradiation mode, an intermediate irradiation mode in which the energy storage circuit is charged with an energy higher than the energy charged in the weak irradiation mode and lower than the energy charged in the main irradiation mode ( An intermediate irradiation stage) may be applied.

It is a figure which shows the flash discharge lamp lighting device used in the 1st and 2nd Example of this invention. It is a figure which shows a flash discharge lamp. It is a figure which shows the light irradiation device of this invention. It is a figure which shows the flash discharge lamp lighting device by the 3rd Example of this invention.

  FIG. 1 is a diagram of a flash discharge lamp lighting device (hereinafter referred to as a “lighting device”) used in the first and second embodiments of the present invention. The lighting device includes a rectifier (11, 12) that rectifies and smoothes the AC power supply 10, a booster circuit (13-18, 25) that boosts the output of the rectifier, and a storage circuit (19-22) that charges the output of the booster circuit. ), A start-up circuit (26, 27) for causing the flash discharge lamp 24 to break down and supplying energy from the power storage circuit to the flash discharge lamp 24, and a series of multiple times to the flash discharge lamp 24. A control unit 30 is provided for controlling the boosting charging circuit and the starting circuit for lighting. It should be noted that it is convenient for each circuit element to belong to which circuit, and the present invention is not bound thereto.

  In FIG. 1, the input power supply is a single-phase power supply, but may be a three-phase power supply. Further, although the rectifying unit is illustrated with the rectifying circuit 11 and the smoothing capacitor 12, it may be configured with a boost chopper circuit or the like. Note that when a DC power source is connected as an input power source, the rectifying unit may not be provided. In the case where the rectifying unit is configured by a boost chopper circuit, the boost function of the boost circuit may be provided on the boost chopper circuit side.

  The booster circuit is composed of a booster inverter circuit including a full bridge circuit (13-16) for AC-converting the output of the rectifier. In the full bridge circuit, when the boost control circuit 25 receives a charge start command from the control unit 30, the transistors 13 and 16 and the transistors 14 and 15 are alternately turned on / off at a high frequency of about 50 kHz. By this switching operation, the DC input from the rectifying unit is AC converted. The AC output of the full bridge circuit is current-limited by the inductor 17 and input to the primary winding of the step-up transformer 18, and a voltage boosted according to the turn ratio of the step-up transformer 18 is generated in the secondary winding. The voltage generated in the secondary winding of the step-up transformer 18 is rectified by the diode bridge 19-21, and this is charged in the storage capacitor (storage element) 22. The charging voltage during the charging operation increases at a charging rate determined by the inductance on the primary winding side of the inductor 17 and the step-up transformer 18, the switching pulse width or switching frequency of the full bridge circuit, and the capacity of the storage capacitor. When the charging detection means (not shown) (for example, the voltage detection circuit of the storage capacitor 22) detects that the charging voltage value has increased to a predetermined voltage value, the boost control circuit 25 stops the operation of the charging inverter circuit. The charging completion signal is returned to the control unit 30. The predetermined voltage value is, for example, about 2000 to 3000 Vdc.

  After receiving the charge completion signal, the control unit 30 outputs a lighting command to the boost control circuit 25 at a predetermined timing. The boost control circuit 25 outputs a start signal to the igniter circuit 26 in response to the lighting command. When the igniter circuit 26 receives the start signal, the igniter circuit 26 causes the external trigger 27 to generate a high voltage pulse voltage of 10 k to 20 kV.

  When the flash discharge lamp 24 is broken down by a high-pressure pulse from the external trigger 27, the energy charged in the storage capacitor 22 is supplied to the flash discharge lamp 24 while being limited by the discharge current peak control inductor 23. Thereby, the flash discharge lamp 24 is turned on once. This operation from charging to lighting is repeated at a set timing, and a series of lighting is performed a plurality of times.

  In the present invention, the control unit 30 charges the storage circuit with a relatively high energy after the weak irradiation mode in which the storage circuit is charged with a relatively low energy in a series of lightings a plurality of times. It is configured to apply the main irradiation mode.

  When lighting of the flash discharge lamp 24 is detected by a lighting detection unit (not shown), the boost control circuit 25 returns a lighting confirmation signal to the control unit 30. When the flash discharge lamp 24 is stigmatized, the boost control circuit 25 returns a stigma signal to the control unit 30. However, the transmission of the lighting confirmation signal and the astigmatism signal is not an essential operation in the present invention.

  The control unit 30 includes a computer such as a microcomputer or a personal computer, and includes a CPU 31, a memory 32, and, in some cases, an input / output interface 33. As described above, the control unit 30 is configured to turn on the flash discharge lamp 24 at a predetermined timing. Therefore, the predetermined timing may be programmed in the memory 32, read from a removable storage medium, or read from a communication device via a transmission medium. . When the control unit 30 is a personal computer, a user may be able to input a desired timing via the input / output interface 33 according to the manufacturing process. In FIG. 1, the control unit 30 and the boost control circuit 25 are connected by wire, but may be connected by wireless communication.

  FIG. 2 shows a specific configuration of the flash discharge lamp 24 and the external trigger 27 of FIG. A flash discharge lamp (hereinafter referred to as “lamp”) includes a quartz arc tube 101, an anode 102 disposed inside one end of the quartz arc tube 101, a cathode 103 disposed inside the other end of the quartz arc tube 101, and a quartz arc tube. A seal portion 104 that seals both ends of 101, a trigger wire 105 (external trigger) disposed in proximity to the quartz arc tube, and an electrode core rod 106 connected to the anode 102 and the cathode 103, respectively. The anode 102 is made of tungsten, and the cathode 103 is obtained by welding a sintered electrode to the tip of a tungsten electrode. The sintered electrode is made by doping tungsten with barium oxide BaO or aluminum oxide AL203 and baking it.

  FIG. 3 shows the light irradiator of the present invention, with the upper part being a top view and the lower part being a side view. The light irradiator includes an irradiator 301 containing a lamp, a lamp 324 (corresponding to the flash discharge lamp 24 in FIG. 1), a reflector 302, and a duct 303. A substrate 304 such as a semiconductor wafer to be irradiated is disposed to face the lamp 324 and the reflecting mirror 302. Further, it is preferable that the wiring between the trigger wire attached to the lamp 324 and the igniter circuit 26 is short so that the high-pressure pulse from the igniter circuit 26 is not attenuated. Therefore, the igniter circuit 26 is provided in the irradiator 301. The reflector 302 is for efficiently reflecting the discharge light from the lamp to the object to be irradiated, and the duct 303 is a duct for intake or exhaust for cooling (air cooling) the lamp.

  In the present invention, the series of multiple lighting operations includes a weak irradiation stage in which preliminary weak irradiation is performed and a main irradiation stage in which subsequent full-scale curing is brought about. In the weak irradiation stage, the wafer is irradiated to some extent with low irradiation energy so that distortion does not easily occur in the subsequent main irradiation stage, and in the final main irradiation stage, energy necessary for curing the photo-curing material is obtained. throw into. This first weak irradiation can suppress the wafer distortion in the tape or paint curing process, and the distortion should not be a problem even in the vicinity of the outer periphery of a large diameter φ450 mm semiconductor wafer. it can.

In the following embodiments, the following is assumed.
In the light irradiator, a φ450 mm wafer is used, and a tape or paint (hereinafter referred to as “photo-curing material”) is applied on the chip of the wafer.
In order to completely cure the tape affixed to the φ450 mm wafer, the integrated energy value (integrated value or cumulative value of discharge energy from the storage capacitor) when the lamp 324 is turned on needs to be 15000 J or more.
Further, as a tact time of a normal semiconductor manufacturing process, the time that can be spent for lamp lighting is about 10 seconds (the wafer is transported and waited for about 20 seconds thereafter), and about 30 shots in about 10 seconds. The flash is turned on. The lamp lighting cycle PPS (Pulse Per Second) is generally 5 PPS to 10 PPS, although it depends on the charging capability of the power source. Therefore, it is preferable that the tact time and the lamp lighting cycle conform to the above ranges so that a significant change from a general manufacturing method is not required.

Example 1.
In this embodiment, the capacity of the storage capacitor 22 is set to 80 μF, and the charging voltage of the storage capacitor 22 when the lamp is lit can be changed in four stages, 2100 Vdc, 2400 Vdc, 2700 Vdc, and 3000 Vdc, during a series of lighting operations. In this embodiment, only two stages are used). Specifically, the boost control circuit 25 controls the voltage charged in the storage capacitor 22 by controlling the switching pulse width or switching frequency of the full bridge circuit according to the command value from the control unit 30. Table 1 shows the discharge energy E per lighting for each charging voltage. Discharge energy E is the capacitance of the storage capacitor 22 C, when the charging voltage was is V, is calculated by C × V ^2/2. The lamp lighting cycle was set to 5 PPS in consideration of the charging capability of the lighting device.

  As described above, the series of multiple lighting operations includes a weak irradiation stage in which preliminary weak irradiation is performed and a main irradiation stage in which subsequent full-scale curing is performed. In the weak irradiation stage, the wafer is first irradiated with a low irradiation energy so that distortion does not easily occur in the subsequent main irradiation stage. Thereafter, energy necessary for curing the photo-curing material is input at the main irradiation stage. Specifically, in the weak irradiation stage, lighting is performed five times with a charging voltage of 2100 Vdc. Thereafter, in the main irradiation stage, lighting is performed 40 times with a charging voltage of 3000 Vdc. The accumulated (cumulative) energy for the 45 times of lighting is 176 J × 5 + 360 J × 40 = 15280 J. Thereby, 15000J required for hardening of photocuring material is ensured, suppressing the distortion at the time of hardening. Also, the lamp lighting time is 1 second (5 times) +8 seconds (40 times) = 9 seconds, which is a time (10 seconds or less) in which there is no problem in the light irradiation process.

Example 2
In this embodiment, the charging voltage is controlled more finely than in the first embodiment. In other words, a series of lighting operations from the weak irradiation stage where preliminary irradiation is performed, through the intermediate irradiation stage where irradiation is stronger than the weak irradiation stage and weaker than the main irradiation stage, to the main irradiation stage which brings about full-scale curing. The charging voltage is gradually increased. Other conditions are the same as those in the first embodiment. In the weak irradiation stage, the lighting is performed 5 times with a charging voltage of 2100 Vdc. Subsequently, in the intermediate irradiation stage, the lighting is performed 5 times with a charging voltage of 2400 Vdc, and then the lighting is performed 5 times with a charging voltage of 2700 Vdc. The charging voltage is set to 3000 Vdc and lighted 32 times. The accumulated (cumulative) energy for the lighting of 47 times in total is 176 J × 5 + 230 J × 5 + 292 J × 5 + 360 J × 32 = 151010J. Thereby, 15000J required for hardening of photocuring material is ensured, suppressing the distortion at the time of hardening. The lamp lighting time is also 1 second (5 times) + 1 second (5 times) + 1 second (5 times) + 6.4 seconds (32 times) = 9.4 seconds, and there is no problem in the light irradiation process (10 Seconds or less).

Example 3
In the first and second embodiments, the configuration in which the charging voltage value is changed using a single storage capacitor is shown, but in this embodiment, the storage capacitor has a variable storage capacity.
FIG. 4 shows a flash discharge lamp lighting device according to this embodiment. The difference from FIG. 1 is that a storage capacitor 28 and a switch 29 for switching its connection state are connected in parallel to the storage capacitor 22 in the storage circuit. In the present embodiment, in a series of lightings a plurality of times, the control unit 30 switches the switch 29 to increase the combined capacity of the power storage elements 22 and 28.

  Specifically, the capacitances of the storage capacitors 22 and 28 are 30 μF and 50 μF, respectively, so that the combined capacitance when the switch 29 is off is 30 μF, and the combined capacitance when the switch 29 is on is 80 μF. The charging voltage was set to 3000 Vdc. Thus, the discharge energy when the switch 29 is off is 135 J, and the discharge energy when it is on is 360 J. In this embodiment, the lamp lighting cycle is 5 PPS.

  In this embodiment, like the first embodiment, a series of lighting operations includes a weak irradiation stage in which preliminary weak irradiation is performed and a main irradiation stage in which subsequent full-scale curing is performed. Specifically, in the weak irradiation stage, the switch 29 is turned off and the discharge energy is set to 135 J, and lighting is performed five times. Thereafter, in the main irradiation stage, the switch 29 is turned on and the discharge energy is set to 360 J and lighting is performed 40 times. . The accumulated (cumulative) energy for the 45 lightings in total is 135 J × 5 + 360 J × 40 = 15075 J. Thereby, 15000J required for hardening of photocuring material is ensured, suppressing the distortion at the time of hardening. Also, the lamp lighting time is 1 second (5 times) +8 seconds (40 times) = 9 seconds, which is a time (10 seconds or less) in which there is no problem in the light irradiation process.

  In this embodiment, the configuration in which the storage capacity is changed in two stages is shown. However, it is also possible to provide a structure in which a larger number of sets of storage capacitors and switches are provided to increase the combined capacity of a plurality of storage capacitors in multiple stages. . Further, although a configuration in which a plurality of storage capacitors are connected in parallel is shown, a configuration in which a plurality of storage capacitors are connected in series and switches are connected in parallel to each capacitor is also possible.

  As described above, it is possible to suppress the generation of strain on the wafer by providing a step of performing weak irradiation with low energy before performing main irradiation with high energy in a series of lighting at a predetermined integrated energy. It was. As a result, even in the light irradiation process of a wafer having a large diameter such as a φ450 mm semiconductor wafer, distortion near the outer periphery does not become a problem, and the yield in semiconductor chip manufacturing can be improved.

In addition, although the said Example was shown as the most suitable example of this invention, the following is noted.
(1) In the embodiment, a circular annular lamp is used as the flash discharge lamp, but the shape is not limited to this. For example, a square annular lamp may be used, and the lamps arranged on the semicircular arc may be connected. An annular shape may be adopted, or a plurality of short straight tube lamps may be arranged in an annular shape to form an annular shape.

  (2) In the embodiment, a power supply unit of a full bridge + step-up transformer type is used, but a booster charging circuit having another configuration may be used as long as a high voltage can be charged. Further, although the storage capacitors 22 and 28 are shown as storage elements, other storage elements such as a battery and an electric double layer capacitor may be used instead of the storage capacitors.

  (3) In the embodiments, the configuration in which the charging voltage is variable and the configuration in which the storage capacity (charging capacity) is variable are individually shown. However, these may be combined to change both the charging voltage and the charging capacity. Moreover, although Example 1 and 2 showed the structure which increases a charging voltage in steps, it is good also as a structure which increases continuously.

  (4) The present invention can be applied not only to a semiconductor chip manufacturing process but also to an adhesive curing process in a DVD bonding process.

13-16. Transistors 17, 23. Inductor 18. Step-up transformer 19-21. Diode bridge 22, 28. Storage capacitor (storage element)
24. Flash discharge lamp 25. Boost control circuit 26. Igniter circuit 27. External trigger 29. Switch 30. Control unit 31. CPU
32. Memory 33. Input / output interface 101. Quartz arc tube 102. Anode 103. Cathode 104. Sealing part 105. Trigger wire 106. Electrode core rod 301. Irradiator 302. Reflector 303. Duct 304. Semiconductor wafer (substrate)
324. lamp

Claims (9)

A flash discharge lamp lighting device for lighting a flash discharge lamp to cure a photo-curing material attached to a substrate,
A step-up charging circuit comprising a step-up circuit for stepping up an input voltage and a storage circuit for charging the output of the step-up circuit;
A starting circuit for causing the flash discharge lamp to break down and causing the flash discharge lamp to input energy from the power storage circuit; and a step-up charging circuit for causing the flash discharge lamp to perform a series of lighting operations. A control unit for controlling the starting circuit;
In the series of lighting, the control unit is configured to perform a main irradiation mode in which the storage circuit is charged with a relatively high energy after the weak irradiation mode in which the storage circuit is charged with the relatively low energy to be turned on. A flash discharge lamp lighting device configured to be applied.   2. The flash discharge lamp lighting device according to claim 1, wherein the control unit controls the booster circuit so that a boosted value by the booster circuit in the weak irradiation mode is lower than a boosted value in the main irradiation mode. Flash discharge lamp lighting device. The flash discharge lamp lighting device according to claim 1, wherein the power storage circuit includes a plurality of power storage elements and a switch for switching a connection state of the plurality of power storage elements,
The flash discharge lamp lighting device, wherein the control unit controls the switch so that a combined capacity of the power storage elements in the weak irradiation mode is smaller than a combined capacity in the main irradiation mode.   2. The flash discharge lamp lighting device according to claim 1, wherein the control circuit has energy charged in the main irradiation mode higher than energy charged in the weak irradiation mode between the weak irradiation mode and the main irradiation mode. A flash discharge lamp lighting device configured to apply an intermediate irradiation mode in which lower energy is charged in the power storage circuit to be lit.   5. A flash discharge lamp lighting device according to any one of claims 1 to 4 and a light irradiator comprising the flash discharge lamp. A boosting circuit comprising a boosting circuit for boosting the input voltage and a storage circuit for charging the output of the boosting circuit, and a starting circuit for causing the flash discharge lamp to break down and supplying energy from the storage circuit to the flash discharge lamp And a light-curing material attached to the substrate using a flash discharge lamp lighting device having a control unit for controlling the boosting charging circuit and the starting circuit to cause the flash discharge lamp to perform a series of lightings a plurality of times. A method of curing
In the series of lighting,
A method comprising: a weak irradiation stage in which a relatively low energy is charged into the power storage circuit to be lit; and a main irradiation stage in which a relatively high energy is charged into the power storage circuit and is lit after the weak irradiation stage.   7. The method according to claim 6, wherein in the weak irradiation stage, the boosted value by the boosting circuit is controlled to be lower than the boosted value in the main irradiation stage. The method according to claim 6, wherein the power storage circuit includes a switch for switching the connection states of the plurality of power storage elements and the plurality of power storage elements,
In the weak irradiation stage, the combined capacity of the plurality of power storage elements is controlled to be smaller than the combined capacity in the main irradiation stage.   7. The method according to claim 6, wherein the control circuit further has an energy charged in the main irradiation stage higher than energy charged in the weak irradiation stage between the weak irradiation stage and the main irradiation stage. A method including an intermediate irradiation step of charging and irradiating the energy storage circuit with lower energy.

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