Flash irradiation device

Abstract

The invention provides a flash irradiation device which can suppress output reduction when flash irradiation is repeatedly performed and has higher energy efficiency than before when a flash lamp is turned on. The flash irradiation device includes: a flash lamp including a first terminal and a second terminal; a capacitor including a first electrode and a second electrode; a first switching element that controls a connection state between the flash lamp and the capacitor; a second switching element arranged in parallel with the first switching element and controlling a connection state between the flash lamp and the capacitor; and a control unit for controlling the first and second switching elements, the control unit executing: a first control for applying a voltage to the flash lamp by repeatedly performing on-off control of the second switching element at a high speed when the first switching element is in an off state; and a second control in which the first switching element is turned on during execution of the first control, and main discharge is generated on the basis of the residual voltage of the capacitor.

Description

Technical Field

[0001] This invention relates to a flash illumination device. Background Technology

[0002] Previously, heat treatment in manufacturing processes such as semiconductor wafer heat treatment and printable electronics involved flash irradiation. In recent years, in particular, with the miniaturization of semiconductor processes, instantaneous heat treatment methods using flash irradiation devices have attracted attention as a way to simultaneously suppress the diffusion of implanted impurities due to prolonged heating and to activate them.

[0003] However, in a flash unit, a portion of the glass material constituting the light-emitting tube evaporates during the flash, or the oxygen contained in the glass material is released, sometimes resulting in a white haze on the inner wall of the light-emitting tube. This white haze tends to become more pronounced with repeated flashes, causing a decrease in the flash output.

[0004] Therefore, the applicant has developed a flash lamp lighting device, as shown in Patent Document 1 below. In Patent Document 1, from the viewpoint of suppressing the whitening of the inner wall of the light-emitting tube caused by repeated flash irradiation, a lamp lighting device is disclosed that can perform flash irradiation in a state where a pre-ignition discharge is formed near the tube axis of the light-emitting tube.

[0005] Existing technical documents Patent documents Patent Document 1: Japanese Patent Application Publication No. 2009-164080 Summary of the Invention

[0006] The technical problem that the invention aims to solve Figure 12 This is a schematic diagram illustrating the circuit configuration of the lamp-lighting device in Patent Document 1. (See diagram for example.) Figure 12 As shown, the lamp lighting device 100 includes a flash lamp 70, a capacitor 80, an inductor 81, a resistor 82, a switching element 83, a trigger electrode 90, and a trigger circuit 91.

[0007] in addition, Figure 13 It is a schematic representation Figure 12 A diagram illustrating the configuration of a 70mm flash unit. Figure 13 The document also describes the XYZ coordinate system, which defines the vertically upward direction as the Z direction and the plane orthogonal to the Z direction as the XY plane. For example... Figure 12 and Figure 13As shown, the flash lamp 70 has a light-emitting tube 71 encapsulated with discharge gas and a pair of electrodes (72, 73) disposed within the light-emitting tube 71. Terminal 70a on the electrode 72 side is electrically connected to electrode 80a of capacitor 80 via inductor 81. Additionally, terminal 70b on the electrode 73 side is electrically connected to electrode 80b of capacitor 80 via switching element 83 (see reference). Figure 12 ).

[0008] The switching element 83 can switch between on and off states via a control circuit (not shown), and the control terminal 70b is electrically connected to the electrode 80b.

[0009] When the resistor 82 is configured in parallel with respect to the switching element 83, it is electrically connected to the terminal 70b of the flash lamp 70, the node N10 connected to the switching element 83, and the electrode 80b of the capacitor 80.

[0010] The trigger circuit 91 is a circuit that applies a voltage to the trigger electrode 90 to induce an insulation breakdown within the light-emitting tube 71 of the flash lamp 70. The trigger electrode 90 is, for example, made of a tungsten metal rod, with a pair of electrodes (72, 73) extending in opposing directions. Figure 13 As shown, the trigger electrode 90 is positioned vertically below the flash lamp 70.

[0011] Figure 14 It means Figure 12 The timing diagram of the operation of the lamp lighting device 100. Figure 14 The charging voltage V of capacitor 80 is shown in the figure. c The current I input to the flash lamp 70 F And the timing of the on / off control of the switching element 83. For example... Figure 14 As shown, capacitor 80 is being charged to the desired charging voltage V by a power source (not shown). 10 The state is as follows. Then, at time t10, trigger circuit 91 is driven.

[0012] If the trigger circuit 91 is driven and a voltage is applied to the trigger electrode 90 (timing t10), the discharge gas inside the light-emitting diode 71 becomes ionized, resulting in insulation breakdown between a pair of electrodes (72, 73). Consequently, a discharge S10 is formed on the inner wall of the light-emitting diode 71 on the side closest to the trigger electrode 90 (see reference). Figure 13 At this moment, the switching element 83 is in the open state, therefore the current I input from the capacitor 80 to the flash lamp 70... F Limited by resistor 82 (current I) 10 Thus, discharge S10 is maintained by a small limiting current limited by resistor 82. For example, the resistance value of resistor 82 is set to about 10kΩ.

[0013] Discharge S10 is maintained with a weak limiting current, thus, through thermal convection within the light-emitting diode 71, it moves upward in the vertical direction over time (see reference). Figure 13 That is, after the discharge S10 is formed near the inner wall of the light-emitting tube 71, it moves in a manner close to the tube axis of the light-emitting tube 71.

[0014] Then, at timing t20 when the discharge S10 approaches the axis of the LED 71, the switching element 83 is switched to the ON state. Consequently, based on the residual charging voltage in the capacitor 80, a large current (current I) is instantaneously input into the flash lamp 70. 11 The main discharge of the flash lamp 70 is performed. The discharge S10 formed between a pair of electrodes (72, 73) before the main discharge is performed is sometimes referred to as the "pre-fire discharge".

[0015] By performing the main discharge of the flash lamp 70 when the discharge S10 is close to the tube axis of the light-emitting tube 71, the generation of the main discharge near the inner wall of the light-emitting tube 71 can be suppressed, and the generation of white cloudiness on the inner wall of the light-emitting tube 71 is less likely. By suppressing the generation of white cloudiness in the light-emitting tube 71, the output reduction of the flash lamp 70 during repeated flash irradiation can be suppressed, thereby extending the lifespan of the flash lamp 70.

[0016] In the configuration of Patent Document 1, in order to make the discharge S10 float by thermal convection, the current input to the flash lamp 70 needs to be set to a weak limiting current. Regarding this, according to the present invention, through in-depth research, it has been found that when the pre-ignition current is set to a weak limiting current, it is difficult to improve the energy efficiency of the flash lamp when performing flash illumination after the pre-ignition discharge. That is, there is room for improvement in suppressing the generation of white residue in the light-emitting diode while simultaneously improving the energy efficiency of the flash lamp during illumination.

[0017] In view of the above, the object of the present invention is to provide a flash irradiation device that can suppress the output reduction during repeated flash irradiation and has higher energy efficiency than before when the flash lamp is lit.

[0018] Technical solutions for solving technical problems The flash illumination device of the present invention is characterized by comprising: A flashlight, comprising a first terminal and a second terminal, discharges by applying a voltage between the first terminal and the second terminal; A capacitor includes a first electrode that can be electrically connected to the first terminal and a second electrode that can be electrically connected to the second terminal; A first switching element controls the electrical connection between the flash lamp and the capacitor; A second switching element, configured in parallel with respect to the first switching element, controls the electrical connection between the flash lamp and the capacitor; and The control unit controls the on / off switching of the first and second switching elements. The control unit performs the first control and the second control. The first control involves simultaneously keeping the first switching element in an open state while rapidly and repeatedly switching the second switching element on and off, thus applying voltage from the capacitor in a charging state to the flash lamp. The second control involves switching the first switching element to the ON state during the execution of the first control, and applying the residual voltage of the capacitor remaining after the first control to the flash lamp, thereby generating the main discharge.

[0019] The inventors have discovered that by repeatedly switching the second switching element on and off at high speed, the discharge expansion formed within the flash lamp can create a discharge located away from the inner wall of the light-emitting tube. In other words, by performing the first control before performing the second control, the generation of a main discharge near the inner wall of the light-emitting tube can be suppressed. This suppresses the reduction in flash lamp output during repeated flashes.

[0020] Furthermore, through in-depth research by the inventors, it has been discovered that by utilizing the first control to expand the discharge, the energy efficiency of the flash lamp during illumination can be improved compared to the past.

[0021] More specifically, by executing the first control, the ionization of the discharge gas within the light-emitting diode is promoted. After executing the first control, the second control is executed, thereby efficiently generating the main discharge. This is described in detail in the "Detailed Description" section.

[0022] The aforementioned flash illumination device can also be, An inductor is configured in parallel with respect to the first switching element and in series with respect to the second switching element.

[0023] From the viewpoint of minimizing the energy consumed by the capacitor in the first control, it is preferable that the off-time of the second switching element in the first control is longer than its on-time. This configuration is preferred because it allows for adjustment of the current supplied to the flash lamp in the first control via an inductor, and the off-time of the second switching element is easy to design.

[0024] In the aforementioned flash illumination device, it can also be configured such that... The control unit executes the second control after performing the first control for a period of 40ms to 100ms.

[0025] Although the details will be described later, based on the above configuration, it is preferable to generate a main discharge when a stable discharge is formed inside the flash lamp.

[0026] Furthermore, in the aforementioned flash illumination device, it is also possible to have: The control unit is configured to perform the second control after a predetermined time has elapsed since the start of the first control. The specified time is the time during which the discharge diameter of the discharge formed in the first control is more than half the diameter of the light-emitting tube of the flash lamp.

[0027] In the aforementioned flash illumination device, it could also be that... After the second control begins, the control unit disconnects the second switching element to stop the first control.

[0028] Alternatively, the aforementioned flash illumination device may also include: A trigger electrode, configured along the axis of the light-emitting diode of the flash unit, assists in starting the flash unit; and A support unit that supports the object being illuminated by the flash emitted by the flash lamp. The trigger electrode is positioned on the outside of the space between the light-emitting tube and the object being irradiated.

[0029] In apparatuses that illuminate objects such as semiconductor wafers with flash, auxiliary heating mechanisms such as halogen heaters and LEDs are sometimes positioned below the vertical direction of the object being illuminated, typically with the flash lamp mounted above the object in the vertical direction. Here, as exemplified in Patent Document 1, in a configuration where heat convection causes a discharge formed within the flash lamp to rise and move it away from the inner wall of the light-emitting diode, the trigger electrode needs to be positioned below the vertical direction of the light-emitting diode. In this case, the trigger electrode is positioned within the space between the light-emitting diode and the object being illuminated, thus partially blocking the flash emitted by the flash lamp. As a result, it is difficult to uniformly illuminate the object with flash.

[0030] In contrast, in the above configuration, by executing the first control, the discharge expansion formed within the flash lamp can be positioned on the inner wall of the light-emitting tube, away from the flash lamp. That is, in the configuration where the discharge formation position is away from the inner wall of the light-emitting tube by the first control, the location of the trigger electrode is not limited to below the vertical direction of the light-emitting tube. According to the above configuration, the trigger electrode is preferably positioned outside the space between the light-emitting tube of the flash lamp and the object being illuminated, so the flash is not blocked by the trigger electrode. For example, the trigger electrode can also be positioned above the vertical direction of the light-emitting tube.

[0031] Invention Effects According to the present invention, a flash illumination device is provided that can suppress the output reduction during repeated flash illumination and has higher energy efficiency when the flash lamp is lit than before. Attached Figure Description

[0032] Figure 1 This is a diagram illustrating the configuration of one embodiment of the flash irradiation device of the present invention.

[0033] Figure 2 This is a cross-sectional view showing an example of the configuration of a flash unit.

[0034] Figure 3 This is a block diagram illustrating an example of the structure of the control unit.

[0035] Figure 4 This is a timing diagram illustrating an example of the operation of a flash illumination device.

[0036] Figure 5 This is a diagram that schematically illustrates the discharge process inside a light-emitting diode.

[0037] Figure 6 This is an example of a scene where a flash of light is shone on an object.

[0038] Figure 7 This is a diagram showing the configuration of the flash illumination device used to verify Comparative Example 1.

[0039] Figure 8 This is a graph representing the output characteristics of the flash irradiation device of Embodiment 1.

[0040] Figure 9 It is a graph representing the evaluation results of the flash unit's lifespan.

[0041] Figure 10 This is a timing diagram illustrating another example of the operation of a flash illumination device.

[0042] Figure 11 It is an imitation Figure 1 A diagram showing an example of the configuration of a flash illumination device.

[0043] Figure 12 This is a schematic diagram illustrating the circuit configuration of the lamp lighting device of Patent Document 1.

[0044] Figure 13 It is a schematic representation Figure 12 A diagram showing the composition of a flash unit.

[0045] Figure 14 It means Figure 12 The timing diagram of the operation of the lamp lighting device.

[0046] Explanation of reference numerals in the attached figures 1: Flash illumination device 2: Flash 2a: First terminal 2b: Second terminal 4: Capacitor 4a: First electrode 4b: Second electrode 6: Inductor 11: First switching element 12: Second switching element 15: Control Department 15a: First conduction control unit 15b: Second conduction control unit 15c: Start-up control unit 20: LED 21, 22: Electrodes 25: Trigger electrode 26: Trigger circuit 30, 31, 32: Diodes 40: Support unit. Detailed Implementation

[0047] Hereinafter, the configuration of the flash irradiation device of the present invention will be described with reference to the accompanying drawings. Furthermore, all the following drawings are schematic illustrations, and the size ratios and numbers shown in the drawings may not necessarily correspond to the actual size ratios and numbers.

[0048] Figure 1 This is a diagram illustrating the configuration of one embodiment of the flash illumination device of the present invention. (See diagram for example.) Figure 1 As shown, the flash illumination device 1 includes a flash lamp 2, a capacitor 4, an inductor 6, a first switching element 11, a second switching element 12, and a control unit 15.

[0049] Figure 2 This is a cross-sectional view showing an example of the configuration of flash unit 2. Figure 2 The document also describes an XYZ coordinate system, which defines the direction parallel to the tube axis A1 of the light-emitting tube 20 as the X direction and the plane orthogonal to the X direction as the YZ plane. This coordinate system will be used with appropriate reference in the following description. In this embodiment, the Z direction corresponds to the vertically upward direction.

[0050] Furthermore, in the following explanation, when indicating direction, positive and negative directions will be distinguished, such as "+X direction" and "-X direction" using positive and negative symbols. However, when indicating direction without distinguishing positive and negative directions, it will only be described as "X direction". That is, in this specification, the use of "X direction" includes both "+X direction" and "-X direction". This also applies to the Y and Z directions.

[0051] like Figure 2 As shown, the flash lamp 2 includes: a light-emitting tube 20, which is filled with a discharge gas such as xenon; an anode 21; a cathode 22; a first terminal 2a, which is composed of a lead wire connected to the anode 21 side; and a second terminal 2b, which is composed of a lead wire connected to the cathode 22 side. The anode 21 and the cathode 22 are arranged separately from each other in the X direction, that is, in the direction of the tube axis A1 of the light-emitting tube 20.

[0052] In addition, such as Figure 2 As shown, the flash lamp 2 has a trigger electrode 25 disposed near the outer peripheral surface of the light-emitting diode 20. As an example, the trigger electrode 25 is made of a tungsten metal rod and is disposed such that it extends in the direction of the tube axis A1 of the light-emitting diode 20. In this embodiment, the trigger electrode 25 is disposed on the +Z side of the flash lamp 2, that is, above it in the vertical direction. Figure 1 As shown, the trigger electrode 25 is configured to apply a trigger voltage by being driven by the trigger circuit 26.

[0053] The light-emitting tube 20 is made of glass material such as quartz glass. As an example, the length of the light-emitting tube 20 in the X direction is 200 mm or more and 500 mm or less, and the thickness of the light-emitting tube 20 is 0.8 mm or more and 3 mm or less. In addition, the outer diameter of the light-emitting tube 20 is 10 mm or more and 30 mm or less.

[0054] Although the illustration is omitted, the number of flash lamps 2 in the flash illumination device 1 is not limited.

[0055] The anode 21 and cathode 22 are made of, for example, a metallic material such as tungsten and are disposed within the light-emitting tube 20. More specifically, the cathode 22 may also be made of tungsten containing a substance (also called an "emitter") that has the effect of reducing the work function. Examples of such emitters include barium aluminate, lanthanum oxide, and thorium oxide.

[0056] like Figure 1 As shown, capacitor 4 has a first electrode 4a that can be electrically connected to a first terminal 2a of flash lamp 2 and a second electrode 4b that can be electrically connected to a second terminal 2b of flash lamp 2. The first electrode 4a and the second electrode 4b can be connected to a power source (not shown), and capacitor 4 is configured to be charged by the power source.

[0057] like Figure 1 As shown, the first switching element 11 is disposed between node N1, which is connected to the second electrode 4b of the capacitor 4, and node N2, which is connected to the second terminal 2b of the flash lamp 2. The first switching element 11 controls the electrical connection between the second terminal 2b of the flash lamp 2 and the second electrode 4b of the capacitor 4. Additionally, as... Figure 1 As shown, a diode 30 is connected between the first switching element 11 and node N1.

[0058] like Figure 1 As shown, the second switching element 12 connects nodes N1 and N2 in a parallel configuration relative to the first switching element 11. The second switching element 12 controls the electrical connection between the second terminal 2b of the flash lamp 2 and the second electrode 4b of the capacitor 4. In this embodiment, an inductor 6 is connected between the second switching element 12 and node N2. Furthermore, similar to the first switching element 11, a diode 31 is connected between the second switching element 12 and node N1.

[0059] For example, the first switching element 11 and the second switching element 12 are composed of IGBTs (Insulated Gate Bipolar Transistors), and the control unit 15 controls the voltage applied to the control terminal to switch between the on and off states. The configuration of the control unit 15 will be described later.

[0060] Furthermore, whether the first switching element 11 and the second switching element 12 are composed of IGBTs is arbitrary. The first switching element 11 and the second switching element 12 can be configured arbitrarily as long as they can change the electrical connection state according to the control signal from the control unit 15.

[0061] Diode 30 is connected to a first switching element 11 on its anode side to suppress reverse current flowing into the first switching element 11 due to back electromotive force. Similarly, diode 31 is connected to a second switching element 12 on its anode side to suppress reverse current flowing into the second switching element 12. Furthermore, the present invention is not limited to the presence or absence of diodes (30, 31).

[0062] One terminal of inductor 6 is connected to the second switching element 12 at node N3, and the other terminal is connected to node N2. That is, as shown... Figure 1 As shown, inductor 6 is configured in parallel with respect to the first switching element 11 and in series with respect to the second switching element 12. When the second switching element 12 is turned on, inductor 6 adjusts the time constant of the current supplied to the flash lamp 2. That is, it adjusts the rise and fall rates of the current supplied from capacitor 4 to flash lamp 2.

[0063] Furthermore, in this embodiment, the flash illumination device 1 includes a diode 32 (see reference) that connects node N3 to node N4, which is connected to the first terminal 2a of the flash lamp 2. Figure 1 The anode of diode 32 is located on the node N3 side, and the cathode is located on the node N4 side. As will be described later, from the viewpoint of suppressing the reverse current flowing into the second switching element 12 due to the back electromotive force of inductor 6 when performing the on / off control of the second switching element 12, the flash irradiation device 1 preferably includes diode 32. In addition, by including diode 32, it is preferable to easily protect the circuit, for example, when a high voltage of 1000V or more is applied.

[0064] like Figure 1 As shown, the control unit 15 is connected to the first switching element 11, the second switching element 12, and the trigger circuit 26. More specifically, the control unit 15 is connected to the gate terminals of the first switching element 11 and the second switching element 12. The control unit 15 is a control unit capable of sending control signals to the first switching element 11 and the second switching element 12, and is configured, for example, to include a processor such as a CPU and a memory for storing information.

[0065] Figure 3 This is a block diagram illustrating an example of the configuration of the control unit 15. For example... Figure 3 As shown, the control unit 15 includes: a first conduction control unit 15a, which controls the on and off states of the first switching element 11; a second conduction control unit 15b, which controls the on and off states of the second switching element 12; and a start control unit 15c, which controls the drive state of the trigger circuit 26. Additionally, as shown in reference... Figure 11 As will be described later, the first conduction control unit 15a and the second conduction control unit 15b can also be configured separately.

[0066] Next, the operation of the flash illumination device 1 will be explained. Figure 4 This is a timing diagram illustrating an example of the operation of the flash illumination device 1. Figure 4 The diagram shows the charging voltage Vc of capacitor 4 and the current I input to flash lamp 2. F The timing of the on / off control of the first switching element 11 and the second switching element 12.

[0067] First, capacitor 4 is charged by applying a voltage to a power source (not shown). Figure 4 In the process, capacitor 4 is charged to the desired charging voltage V1.

[0068] Next, at time t1, the trigger circuit 26 is driven by the start control unit 15c. Simultaneously, the second switching element 12 is turned on. This applies a trigger voltage to the flash lamp 2 from the trigger electrode 25. When the trigger voltage is applied, the gas inside the light-emitting diode 20 becomes ionized, causing insulation breakdown and generating a discharge between the anode 21 and the cathode 22. Then, through this discharge, current begins to flow through the path where the second switching element 12 is located (see reference...). Figure 1 The current flows to flash unit 2. Additionally, in Figure 4 In this configuration, the second switching element 12 and the trigger circuit 26 are simultaneously turned on, but this is arbitrary. For example, the second switching element 12 can also be turned on at a timed interval before the trigger circuit 26 is driven.

[0069] like Figure 4As shown, after the timing t1 drives the trigger circuit 26, the control unit 15 repeatedly performs high-speed switching control of the on and off states of the second switching element 12.

[0070] exist Figure 4 The diagram schematically illustrates the on-time x1 when the second switching element 12 is in the on state and the off-time x2 when the second switching element 12 is in the off state. As an example, the control unit 15 is configured to control the current I flowing in the flash lamp 2. F Become the specified current value I off At the moment when the second switching element 12 is turned off, the current I... F Become the specified current value I on The control unit 15 is configured to turn on the second switching element 12 at specific times. For example, the control unit 15 has a storage unit (not shown) that performs on / off control of the second switching element 12 based on information stored in the storage unit. Alternatively, the control unit 15 may also perform on / off control of the second switching element 12 based on a predetermined on time x1 and off time x2.

[0071] The rate at which the current flows through the flash lamp 2 rises and falls can be adjusted, for example, by the design of the inductor 6.

[0072] The inventors have discovered that by repeatedly switching the second switching element 12 on and off to supply current to the flash lamp 2, the discharge expansion formed between the anode 21 and the cathode 22 can cause the discharge to form at a position farther from the inner wall of the light-emitting tube 20 than when it is started, more specifically, near the tube axis A1 of the light-emitting tube 20.

[0073] Figure 5 This is a schematic diagram illustrating the discharge within the LED 20. (For example...) Figure 5 As shown, by applying a trigger voltage, insulation breakdown occurs within the LED 20, thereby forming a discharge S1 near the inner wall 20a of the LED 20 on the side closest to the trigger electrode 25. Afterwards, the second switching element 12 is repeatedly switched on and off to supply current to the flash lamp 2, thus achieving the desired effect. Figure 5 As shown, discharge S1 grows and expands, increasing its discharge diameter r1. Furthermore, due to the expansion of discharge S1 controlled by the on / off state of the second switching element 12, it forms at a position farther from the inner wall 20a of the light-emitting diode 20 (discharge S2) compared to the initial state. Figure 5 In the diagram, the position of discharge S1 immediately after activation is represented by a dashed line, while the position of discharge S2 after expansion is represented by a solid line.

[0074] Thus, the control unit 15's high-speed switching of the on and off states of the second switching element 12 corresponds to "first control".

[0075] like Figure 4 As shown, after a predetermined time Tx elapsed since the start of the on / off control of the second switching element 12 (first control), the control unit 15 sets the first switching element 11 to the on state at a time t2. As a result, based on the charging voltage remaining in the capacitor 4, a large current is instantaneously input to the flash lamp 2, performing the main discharge of the flash lamp 2. As an example, the control unit 15 sets the first switching element 11 to the on state based on information stored in an arbitrary storage unit (not shown).

[0076] Thus, the control unit 15 switches the first switching element 11 to the on state after the first control to generate the main discharge, which corresponds to the "second control".

[0077] For reference Figure 5 As described above, by executing the first control, discharge S2 is formed at a position away from the inner wall 20a. In this state, executing the second control can suppress the generation of main discharge near the inner wall 20a, making the inner wall 20a less prone to clouding. Therefore, it is possible to suppress the decrease in output of the flash lamp 2 during repeated flash irradiation.

[0078] Furthermore, by simultaneously controlling the on / off state of the second switching element 12 at high speed while supplying current, the discharge S2 expands, thereby improving the energy efficiency of the flash lamp 2 when it is lit. This will be described in detail in section "Verification 2".

[0079] like Figure 4 As shown, after the first switching element 11 is set to the on state (second control), the control unit 15 keeps the second switching element 12 in the off state and stops the first control.

[0080] Alternatively, the second switch element 12 can be set to the off state simultaneously with the first switch element 11 being set to the on state. However, it is conceivable that even if the control unit 15 simultaneously sends control signals to both the first switch element 11 and the second switch element 12, the timing of the first switch element 11 becoming the on state and the timing of the second switch element 12 becoming the off state will deviate. In this case, the discharge S2 may be reduced from the time the second switch element 12 becomes the off state until the first switch element 11 becomes the on state. Therefore, it is preferable to stop the first control after the second control begins.

[0081] As a result of repeatedly switching on and off in the second switching element 12, a smaller current flows compared to the first switching element 11. Therefore, the rated current of the second switching element 12 can also be smaller than the rated current of the first switching element 11. For example, the rated current of the second switching element 12 can be set to a range of 1A or more and 100A or less. Furthermore, the rated current of the first switching element 11 can also be set to a range of 1000A or more and 5000A or less.

[0082] As described above, by controlling the on / off state of the second switching element 12 (first control), a discharge S2 is formed near the tube axis A1 of the light-emitting diode 20. In this state, the second control is executed, thereby enabling the main discharge of the flash lamp 2 to be generated starting from the discharge S2. As a result, the generation of the main discharge near the inner wall 20a of the light-emitting diode 20 is suppressed, and the whitening of the inner wall 20a is less likely to occur, thus extending the lifespan of the flash lamp 2.

[0083] That is, according to this embodiment, as referred to Figures 12-14 Similar to the discharge between electrodes being floated up by thermal convection, a discharge S2 can be formed near the tube axis A1 of the light-emitting diode 20. Furthermore, in Figure 12 In the example, in order to make the discharge S10 float, the trigger electrode needs to be positioned below the vertical direction (-Z side) of the light-emitting diode 71. In contrast, in this embodiment, the discharge S2 expands by controlling the on / off state of the second switching element 12, so the position of the trigger electrode 25 is not limited.

[0084] Figure 6 This is an example of a scene where a flash of light is shone on an object. Figure 6 The attached diagram corresponds to the view of flashlight 2 when viewed along the X direction. (See attached diagram.) Figure 6 As shown, the flash illumination device 1 has a support unit 40 on the -Z side (vertical direction, below) of the flash lamp 2 to support the object to be illuminated, W1. The object to be illuminated, W1, is, for example, a semiconductor wafer such as a silicon substrate. As an example, the support unit 40 is configured to support the object to be illuminated, W1, by a negative pressure generated by a suction mechanism (not shown). The configuration of the support unit 40 is arbitrary as long as it can support the object to be illuminated, W1, in a state where the main surface of the object to be illuminated is parallel to the XY plane. For example, the support unit 40 may also have multiple pin-shaped protrusions that support the object to be illuminated, W1.

[0085] When illuminating the object W1 with a flash, such as Figure 6As shown, typically, the flash lamp 2 is mounted above the object W1 in the vertical direction (+Z side). Here, assuming the trigger electrode is positioned below the flash lamp 2 in the vertical direction (-Z side), a portion of the flash emitted by the flash lamp 2 is blocked by the trigger electrode, resulting in difficulty in uniformly illuminating the object W1. In contrast, in this embodiment, the trigger electrode 25 is positioned above the light-emitting diode 20 in the vertical direction (+Z side), so the flash is not blocked by the trigger electrode 25, which is preferable.

[0086] In view of the above, the trigger electrode 25 is preferably disposed in the space P1 between the light-emitting tube 20 and the irradiated object W1 (see reference). Figure 6 The trigger electrode 25 is positioned on the outside of the flash lamp 20. This allows for the suppression of a portion of the flash emitted by the flash lamp 2 from being blocked by the trigger electrode 25. More preferably, the trigger electrode 25 is positioned on the opposite side of the object W1 to be illuminated, with respect to the light-emitting tube 20.

[0087] [Verification 1] It has been confirmed that the lifespan of the flash lamp 2 can be extended by repeatedly switching the second switching element 12 on and off before the main discharge is executed, and therefore will be explained below.

[0088] (Example 1) Prepare for reference Figure 1 The aforementioned flash illumination device, after repeatedly switching the second switching element 12 on and off at high speed (first control), executes the second control to generate the main discharge of the flash lamp 2 (see also...). Figure 4 ).

[0089] In this verification, the operation of charging capacitor 4 to the specified charging voltage and then generating the main discharge of flash 2 was repeated approximately 100,000 times to confirm the shift in the output of flash 2. The detailed conditions are shown below.

[0090] The capacitor's capacitance is 200μF. In the first control, the current value I that makes the second switching element 12 open is... off 9A In the first control, the current value I that makes the second switching element 12 turn on is... on 6A The time Tx from the start of the first control to the execution of the second control is 80ms. The inner diameter of the LED 20 in flash unit 2 is 10mm. Xenon discharge gas (sealing pressure: 60 kPa) The distance between anode 21 and cathode 22 is 400mm. (Comparative Example 1) Figure 7This diagram shows the configuration of the flash illumination device used to verify Comparative Example 1. Figure 7 In the middle, to and Figure 1 Common elements are labeled with common reference numerals. In the flash illumination device 60, as shown... Figure 7 As shown, a resistor 50 is disposed between node N3 and the second switching element 12. Furthermore, in Comparative Example 1, while the first switching element 11 is in the off state and the second switching element 12 is in the on state, the trigger circuit 26 is driven to supply a limiting current limited by the resistor 50 to the flash lamp 2.

[0091] In Comparative Example 1, the trigger electrode 25 is disposed below the light-emitting diode 20 in the vertical direction. That is, Comparative Example 1 is configured such that the discharge formed by applying the trigger voltage is maintained by limiting the current, while the discharge is made to float by thermal convection. The difference between Comparative Example 1 and Example 1 is that after the trigger circuit is driven, the first control that repeatedly controls the on and off of the second switching element 12 is not executed; instead, the main discharge is executed after the aforementioned limiting current is supplied for a predetermined time.

[0092] The limiting current is approximately 0.1A, and the main discharge is performed at a timed interval, with the discharge formed between a pair of electrodes approaching the axis of the LED 20. The supply time of the limiting current is 80ms.

[0093] Then, the operation from charging capacitor 4 to generating the main discharge of flash lamp 2 is repeated approximately 100,000 times to confirm the progression of flash lamp 2 output. For safety, in Comparative Example 1, the residual voltage at the moment of execution of the main discharge of capacitor 4 is equal to the residual voltage at the moment of execution of the main discharge (time t2) in Example 1.

[0094] [Result of Verification 1] Figure 8 This is a graph representing the output characteristics of the flash irradiation device of Embodiment 1. Figure 8 In the diagram, the vertical axis represents the current supplied to the flash unit, and the horizontal axis represents the elapsed time since the trigger voltage was applied. Additionally, in... Figure 8 The diagram schematically illustrates timing t2 when the first switching element 11 is set to the ON state after the pre-ignition discharge is performed. According to... Figure 8 It is understandable that after the first switching element 11 is turned on, a large current is instantly input to the flash lamp 2 to perform the main discharge.

[0095] When flash-irradiating an object W1, such as a semiconductor wafer, it is preferable to shorten the flash irradiation time of the flash lamp 2 from the viewpoint of suppressing impurity diffusion. Specifically, the flash irradiation time is preferably 1 second or less, and more preferably 100 msec or less. The flash irradiation time can also be set as the half-width of a graph representing the current value relative to the elapsed time. (Refer to...) Figure 8It is known that the flash irradiation time is approximately 0.14 msec, and the flash irradiation device 1 is suitable for flash irradiation of semiconductor wafers and the like.

[0096] Figure 9 This is a graph representing the evaluation results of the lifespan of flash unit 2. In Figure 9 In the diagram, the vertical axis represents the flash sustain rate, and the horizontal axis represents the number of flashes fired. The flash sustain rate is the maximum current I during each firing. max Compared to the maximum current I during initial lighting max The proportion.

[0097] like Figure 9 As shown, in Comparative Example 1, the output maintenance rate after 100,000 illuminations is approximately 90%, demonstrating good lifespan characteristics. In Comparative Example 1, the main discharge is performed at a timed interval, with the discharge formed between a pair of electrodes approaching the tube axis of the LED 20. This demonstrates that the generation of the main discharge near the inner wall of the LED 20 is suppressed, thus preventing the reduction in flash lamp output caused by cloudiness on that inner wall.

[0098] In addition, such as Figure 9 As shown, in Example 1, the output maintenance rate after 100,000 cycles is approximately 90%, exhibiting the same good lifespan characteristics as Comparative Example 1. (See reference...) Figure 5 The discharge S2 is formed at a location away from the inner wall 20a of the light-emitting diode 20 by repeatedly switching the second switching element 12 on and off (first control). That is, it is believed that by executing the second control to generate the main discharge after executing the first control, the generation of the main discharge near the inner wall 20a is suppressed, and as a result, the output reduction of the flash lamp is suppressed in the same way as in Comparative Example 1. This verification demonstrates that by generating the main discharge after repeatedly switching the second switching element 12 on and off, the output reduction of the flash lamp during repeated main discharges can be suppressed.

[0099] [Verification 2] Next, the effect of the first control, which repeatedly controls the on / off state of the second switching element 12, on the energy efficiency of the flash lamp was verified, and therefore the following description is based on the embodiment.

[0100] (Example 2) In Example 1 of the above verification 1, the time Tx from the start of the first control to the execution of the second control is changed to 5 msec. In this verification, the charging voltage of the capacitor at the moment of execution of the second control is approximately 3600V. Then, the output O of the flash lamp during the main discharge is measured using a calorimeter (OPHIR L30A-SH-V1). p The energy efficiency O of the flash lamp is obtained according to the following equation (1). EIn equation (1) below, U corresponds to the charging energy of the capacitor at time t2. Additionally, the output O... p The measurement was performed 5 times, and the average value was used.

[0101] O E =O p / U...(1) (Example 3) Except that the time Tx is changed to 45 msec, it is performed under the same conditions as in Example 2.

[0102] (Example 4) Except that the time Tx is changed to 80 msec, it is performed under the same conditions as in Example 2.

[0103] (Comparative Example 2) Under the same conditions as Comparative Example 1 of Verification 1 above, the main discharge of the flash lamp was performed after the discharge formed between a pair of electrodes was maintained by limiting the current and then floated up by thermal convection. The charging voltage of the capacitor at the moment of execution of the main discharge was adjusted to 3600V, and the energy efficiency of the flash lamp was O. E The measurement method is the same as in Example 2.

[0104] [Result of Verification 2] The energy efficiency O of each embodiment is shown in Table 1 below. E The results of the comparison are shown in Table 1, with energy efficiency O of Comparative Example 2 shown for each embodiment. E The relative value is based on the baseline.

[0105] [Table 1] According to Table 1, it can be understood that the energy efficiency of Example 2 is greater than that of Comparative Example 2. Furthermore, this is also true for Examples 3 and 4. Although the charging voltage of the capacitor is the same at the time of the main discharge execution, the discharge expansion is controlled by the on / off state of the second switching element 12, thereby improving the energy efficiency of the flash lamp compared to the discharge being floated by thermal convection. Regarding this, the inventors speculate as follows: In order to float the discharge by thermal convection, compared to setting the current supplied to the flash lamp during discharge to a weak limiting current, by repeatedly supplying a current of approximately several amperes, the discharge gas is ionized within the light-emitting tube 20. As a result, the energy required for ionization in the main discharge during flash irradiation is reduced, and the luminous efficiency in the main discharge is improved. In other words, it can be said that it is difficult to improve the energy efficiency of the flash lamp when a pre-ignition discharge is formed with a weak limiting current.

[0106] According to this verification, it is shown that by repeatedly switching the second switching element 12 on and off at high speed, the discharge S2 expands, thereby improving the energy efficiency when the flash lamp is lit compared to the discharge between the electrodes being floated up by thermal convection.

[0107] [Verification 3] To further investigate, a comparison verification was conducted between Example 4 and Comparative Example 3 below. In this verification, in each case, the voltage drop from the charging voltage of capacitor 4 to the voltage at the execution time of the main discharge and the energy efficiency O were measured. E A comparison was made.

[0108] (Comparative Example 3) After driving the trigger circuit 26 by setting the first switching element 11 to the off state and the second switching element 12 to the on state, current is supplied to the flash lamp 2 while keeping the second switching element 12 in the on state during the period before the main discharge is performed. Otherwise, it is performed under the same conditions as in Embodiment 4.

[0109] [Result of Verification 3] In Example 4, the voltage drop from the charging voltage of capacitor 4 to the voltage at the execution time of the main discharge (3600V) is approximately 300V. In contrast, the voltage drop in Comparative Example 3 is approximately 450V. The energy efficiency O is calculated based on the above equation (1). E The results showed that the energy efficiency of both was O E To the same extent. That is, in Example 4, to obtain the same energy efficiency O E At the same time, compared with Comparative Example 3, it also suppressed the consumption of the charging voltage of capacitor 4.

[0110] That is, according to this verification, before performing the main discharge, when supplying current to the flash lamp 2 to cause the discharge expansion in the light-emitting tube 20, compared with keeping the second switching element 12 in the on state, by repeatedly controlling the on and off of the second switching element 12 at high speed, the consumption of the charging voltage of the capacitor 4 can be suppressed.

[0111] [Inspection] As shown in the results of Verification 1, Example 4 achieves the same good lifespan characteristics as Comparative Example 1. Example 4 improves the energy efficiency of the flash lamp while achieving good lifespan characteristics, resulting in excellent performance.

[0112] Furthermore, the inventors observed the discharge formed on the flash lamp 2 using a high-speed camera, and confirmed that at a time 0.5 ms elapsed from the start of the first control, the discharge between the electrodes was located near the inner wall 20a of the light-emitting tube 20. Figure 5The discharge S1 begins to expand after 10 ms, causing regional variation. Furthermore, it was confirmed that after approximately 40 ms, a stable discharge is formed at a position centered on the tube axis A1 of the light-emitting tube 20.

[0113] Therefore, it can be said that in Embodiment 3, where the time Tx from the start of the first control to the execution of the second control is 45 msec, good lifetime characteristics are obtained in the same way as in Embodiment 1. Furthermore, considering that the discharge formation area between the electrodes changes after approximately 10 msec, by executing the first control for about a few msec, it is expected to have the effect of moving the discharge away from the inner wall 20a. Therefore, it is speculated that the lifetime characteristics are also improved in Embodiment 2, where the time Tx is 5 msec.

[0114] Additionally, at a time 40 ms after the first control, the discharge diameter r1 between the electrodes (refer to...) Figure 5 The diameter of the discharge diameter r1 is about half of the inner diameter (10 mm) of the LED 20. Therefore, it is believed that when the time Tx is 45 msec or more, the discharge diameter r1 becomes larger, thereby further improving the energy efficiency (see Table 1).

[0115] As described above, based on the results of Verification 1 and Verification 2, it is shown that by generating the main discharge after repeatedly controlling the on / off state of the second switching element 12, the energy efficiency of the flash lamp can be improved while achieving good lifespan characteristics. Furthermore, based on the results of Verification 3, by employing a configuration that repeatedly controls the on / off state of the second switching element 12, the decrease in the charging voltage of the capacitor 4 during pre-discharge can be suppressed.

[0116] That is, according to the above embodiments, the output reduction during repeated flash illumination can be suppressed, and the energy efficiency of the flash lamp when lit can be improved compared with the past.

[0117] Furthermore, as described above, by setting the time Tx from the start of the first control to the execution of the second control to 40 msec or more, discharge S2 can be stably formed easily. Therefore, time Tx is preferably 40 msec or more. Moreover, by setting time Tx to 40 msec or more, energy efficiency can be significantly improved. E More preferably (refer to Table 1). Furthermore, if the time Tx is too long, the charging voltage of capacitor 4 is prone to decrease. Therefore, the time Tx is preferably set to 100 msec or less.

[0118] Furthermore, considering that the discharge within the LED 20 is prone to expansion before the main discharge is performed, in the first control, the current value I that switches the second switching element 12 to the ON state is... onPreferably, the current value is 3A or higher, and more preferably 5A or higher. Furthermore, from the same viewpoint, in the first control, the current value I that switches the second switching element 12 to the off state is... off Preferably, the current is 7A or higher, more preferably 9A or higher. Furthermore, in the current value I... off If the current is too large, it is assumed that the charging voltage of capacitor 4 will decrease earlier. Therefore, the current value I... off Preferably, the 10A or less is preferred, and more preferably, the 8A or less is preferred.

[0119] Furthermore, in the first control, from the viewpoint of easily suppressing the consumption of the charging voltage of capacitor 4, it is preferable that the off time x2 of the second switching element 12 is longer than the on time x1 (see also...). Figure 4 As an example, the ratio of the turn-on time x1 to the turn-off time x2 is 10% or less. Specifically, the turn-on time x1 is 5 μsec or more and 30 μsec or less. Furthermore, the turn-off time x2 is 50 μsec or more and 1000 μsec or less. Moreover, it is conceivable that if the turn-off time x2 is too long, the pre-ignition discharge will disappear. Therefore, the turn-off time x2 is preferably at least 500 μsec or less.

[0120] In view of the above, the on / off control of the second switching element 12 is preferably executed at a high speed on the order of less than 1 msec.

[0121] (Modified example) The following describes a modified example of the flash illumination device 1.

[0122] <1> As described above, in the first control, it is preferable that the off-time x2 of the second switching element 12 is longer than the on-time x1. From the viewpoint that the off-time x2 can be easily adjusted, such as... Figure 1 As shown, the flash illumination device 1 preferably has an inductor 6 configured in parallel with respect to the first switching element 11 and in series with respect to the second switching element 12. However, in this invention, whether the flash illumination device 1 has an inductor 6 is arbitrary.

[0123] <2> The above describes the case where the first electrode 4a of capacitor 4 and the first terminal 2a of flash lamp 2 are connected without passing through circuit elements (see reference). Figure 1 However, from the viewpoint of adjusting the flash duration of the flash lamp 2, the flash device 1 may, for example, have an inductor connected in series with the flash lamp 2 between the first electrode 4a and the first terminal 2a.

[0124] <3> Figure 10 It is an imitation Figure 4A timing diagram illustrating another example of the operation of the flash illumination device 1. The above describes a situation where, after the first switching element 11 is set to the ON state, the second switching element 12 is kept in the OFF state, and the first control is stopped (see [reference]). Figure 4 However, as Figure 10 As shown, the first switch element 11 can also be set to the on state after the second switch element 12 is set to the off state.

[0125] exist Figure 10 Even after the second switching element 12 is set to the open state, the discharge S2 continues for at least until the open time x2 has elapsed. That is, the period from when the second switching element 12 is set to the open state until the open time x2 has elapsed can also be defined as the execution of the first control.

[0126] <4> For reference Figure 5 By performing the main discharge with the discharge S2 formed at a position away from the inner wall 20a of the light-emitting tube 20, the formation of turbidity in the inner wall 20a can be suppressed. Furthermore, before performing the main discharge, the discharge diameter r1 is increased, thereby ionizing the discharge gas within the light-emitting tube 20 and improving the energy efficiency when the flash lamp is lit. Specifically, it is preferable that the discharge diameter r1 of the discharge S2 is increased when the discharge S2 expands (refer to...). Figure 5 The main discharge is performed after the diameter of the light-emitting tube 20 becomes more than half of its inner diameter. Here, typically, given that the thickness of the light-emitting tube 20 is as small as 3 mm or less, the diameter of the light-emitting tube 20 when compared with the discharge diameter r1 can also be set as the outer diameter of the light-emitting tube 20.

[0127] The time required for the discharge diameter r1 of discharge S2 to become more than half the diameter of the light-emitting diode 20 can be predetermined, for example, by observing discharge S2 using a high-speed camera or the like. Therefore, the control unit 15 may have a storage unit such as a memory to store the time when the discharge diameter r1 becomes more than half the diameter of the light-emitting diode 20, and the control unit 15 may determine the time Tx from the start of the first control to the execution of the second control based on this time.

[0128] <5> Figure 11 It is an imitation Figure 1 The diagram shows an example of the configuration of the flash illumination device 1. In the above description, the control unit 15 includes a first conduction control unit 15a and a second conduction control unit 15b. However, as... Figure 11 As shown, in the flash illumination device 1, the first conduction control unit 15a and the second conduction control unit 15b can also be configured separately. The same applies to the activation control unit 15c.

[0129] <6> The above describes the configuration of the first switching element 11 and the second switching element 12 between node N1 and node N2. However, the configuration of the first switching element 11 and the second switching element 12 is not limited to the above, as long as the electrical connection between the flash lamp 2 and the capacitor 4 can be controlled. For example, the first switching element 11 and the second switching element 12 may also be configured between the first terminal 2a of the flash lamp 2 and the first electrode 4a of the capacitor 4. Furthermore, from the viewpoint of simplifying the design of the reference potential in the switching elements, it is preferable that the first switching element 11 and the second switching element 12 control the electrical connection between the second terminal 2b and the second electrode 4b located on the ground side (see reference). Figure 1 wait).

[0130] <7> The configuration of the flash irradiation device 1 of the present invention is not limited to the above-described embodiments.

Claims

1. A flash illumination device, characterized in that, have: A flashlight, comprising a first terminal and a second terminal, discharges by applying a voltage between the first terminal and the second terminal; A capacitor includes a first electrode that can be electrically connected to the first terminal and a second electrode that can be electrically connected to the second terminal; A first switching element controls the electrical connection between the flash lamp and the capacitor; The second switching element is configured in parallel with the first switching element to control the electrical connection between the flash lamp and the capacitor; as well as The control unit controls the on / off switching of the first and second switching elements. The control unit performs the first control and the second control. The first control involves simultaneously keeping the first switching element in an open state while rapidly and repeatedly switching the second switching element on and off, thus applying voltage from the capacitor in a charging state to the flash lamp. The second control involves switching the first switching element to the ON state during the execution of the first control, and applying the residual voltage of the capacitor remaining after the first control to the flash lamp, thereby generating the main discharge.

2. The flash illumination device according to claim 1, characterized in that, It includes an inductor, which is configured in parallel with respect to the first switching element and in series with respect to the second switching element.

3. The flash illumination device according to claim 1 or 2, characterized in that, The control unit is configured to execute the second control after the first control has been executed for a period of 40 ms or more and 100 ms or less.

4. The flash illumination device according to claim 2, characterized in that, In the first control, the off time of the second switching element is longer than the on time.

5. The flash illumination device according to claim 1 or 2, characterized in that, After the second control begins, the control unit disconnects the second switching element and stops the first control.

6. The flash illumination device according to claim 1 or 2, characterized in that, The control unit is configured to perform the second control after a predetermined time has elapsed since the start of the first control. The specified time is the time during which the discharge diameter of the discharge formed in the first control becomes more than half the diameter of the light-emitting tube of the flash lamp.

7. The flash illumination device according to claim 1 or 2, characterized in that, have: A trigger electrode, configured along the axis of the light-emitting diode of the flash unit, assists in starting the flash unit; and Support unit, which supports the object being illuminated by the flash emitted by the flash lamp. The trigger electrode is positioned on the outside of the space between the light-emitting tube and the object being irradiated.

Images