JP2023142412A - light irradiation device - Google Patents

Abstract

To provide a light irradiation device that can stably irradiate with illumination light having a desired wavelength in a desired amount of light.SOLUTION: A light irradiation device 70 installed in an observation device for observing a semiconductor wafer W includes: a light bulb 701 having a filament; a power source 704 that supplies power to the light bulb 701; a housing 710 that accommodates the light bulb 701; an output port 711 provided in the housing 710 and transmitting light emitted from the light bulb 701; relative distance adjustment means 703 for changing the relative distance between the light bulb 701 and the output port 711; and light amount control means 707 for controlling the amount of light emitted from the output port 711. When the amount of light is changed, the light amount control means 707 changes the relative distance using the relative distance adjustment means 703 while keeping the voltage of the power supplied from the power source 704 constant.SELECTED DRAWING: Figure 3

Description

The present invention relates to a light irradiation device using a light bulb having a filament, and particularly to a light irradiation device suitably included in an observation device for observing semiconductor wafers.

Usually, a light irradiation device is employed as a light source in a microscope or a processing device. A light irradiation device using a light bulb with a filament (filament lamp) is used when a wide band of light is required or when a band of light that cannot be obtained with an LED (Light Emitting Diode) lamp is required.

In this type of light irradiation device, the amount of light is controlled by controlling the voltage applied to the light bulb so that an image with appropriate brightness can be obtained. At this time, since the illuminance of the bulb changes non-linearly with respect to the voltage, the voltage is adjusted to set the desired amount of light.

For example, the light amount control device for a filament lamp described in Patent Document 1 includes a current detection sensor connected in series to a filament lamp having a characteristic that a change in light amount of the lamp is approximately proportional to the square of power consumption, and a terminal of the filament lamp. A multiplication circuit that generates a voltage proportional to the product of the output voltage of the voltage and current detection sensor, a square root circuit that generates a voltage proportional to the square root of the control voltage, and a comparison between the output voltage of the multiplication circuit and the output voltage of the square root circuit. The apparatus includes an error amplifier circuit that minimizes errors, and a constant voltage power supply that is connected to the output terminal of the error amplifier circuit and supplies power to the filament lamp.

Thereby, the light amount control device described in Patent Document 1 can change the light amount of the filament lamp almost linearly with respect to the voltage applied by the constant voltage power supply device.

Japanese Patent Application Publication No. 2004-030927

A light amount control device that changes the voltage applied to a filament lamp in order to control the amount of light changes the spectral distribution of the light from the filament lamp in response to changes in voltage, making it possible to obtain light with a desired wavelength at a desired amount of light. It may be difficult to stably control the

In view of these circumstances, an object of the present invention is to provide a light irradiation device that can stably irradiate illumination light having a desired wavelength with a desired amount of light.

In order to achieve the object of the present invention, a light irradiation device according to a first aspect of the present invention is a light irradiation device provided in an observation device for observing a semiconductor wafer, which includes a light bulb having a filament, and a light bulb having a filament. A power source for supplying electric power, a housing for accommodating the light bulb, an exit port provided in the housing for transmitting light emitted from the light bulb, and a relative distance adjustment means for changing the relative distance between the light bulb and the exit port. , a light amount control means for controlling the amount of light emitted from the light exit; when changing the amount of light, the light amount control means maintains the voltage of the power supplied from the power source constant; The relative distance is changed by the relative distance adjustment means.

According to this aspect, the light intensity is adjusted by changing the relative distance between the light bulb and the exit port while the voltage applied to the light bulb is kept constant. This eliminates the need for a complicated circuit to adjust the voltage of the power supplied to the device. Furthermore, since the amount of light can be adjusted while keeping the voltage of the electric power supplied to the light bulb constant, changes in the spectral distribution of the light from the light bulb due to changes in voltage are suppressed. In turn, it becomes possible to irradiate illumination light having a desired wavelength with a desired amount of light.

According to a second aspect of the present invention, the light irradiation device according to the first aspect further includes a shutter that blocks light and a shutter drive means that drives the shutter, and when the amount of light is set to zero, the amount of light is The control means causes the shutter drive means to move the shutter onto the optical path between the light bulb and the light exit with the light bulb turned on.

According to this aspect, it is possible to reduce the frequency of turning on and off the light bulb during observation using the observation device, for example. Furthermore, it is possible to reduce the time required for soft start to suppress the rush current that occurs when lighting the electric lamp. Further, by reducing the frequency of turning on and off the light bulb, shortening of the life of the light bulb can also be suppressed.

According to the third aspect of the present invention, the light irradiation device according to the first or second aspect further includes a bandpass filter that limits the wavelength band of the light between the light bulb and the exit port.

According to this aspect, the bandpass filter makes it possible to selectively transmit light in a wavelength band suitable for observation among the broadband light emitted from the light bulb, and block light in other bands. .

According to the fourth aspect of the present invention, in the light irradiation device according to the third aspect, the relative distance adjusting means changes the relative distance while keeping the positional relationship between the light bulb and the bandpass filter constant.

According to this aspect, by keeping the positional relationship between the light bulb and the bandpass filter constant, it is possible to suppress changes in the transmission characteristics of the bandpass filter due to temperature fluctuations of the bandpass filter. Furthermore, since the wavelength of the light emitted from the light irradiation device can be stabilized, it becomes possible to stably adjust the brightness of the observed image.

According to the present invention, the amount of illumination light can be changed while the voltage applied to the bulb is kept constant, so that illumination light having a desired wavelength can be stably irradiated with a desired amount of light. becomes possible.

1 is a schematic diagram of the external appearance of a laser processing device having an observation device to which a light irradiation device according to the present invention is applied. 1 is an example of a plan view of a wafer. It is a functional block diagram of a light irradiation device. It is a graph showing an example of the spectral distribution of light from a light bulb. It is a graph which shows an example of the characteristic of a bandpass filter. FIG. 3 is an explanatory diagram of the principle of light amount adjustment. 3 is a graph showing an example of the sensitivity of an InGaAs sensor.

Preferred embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a schematic diagram of the appearance of a laser processing apparatus having an observation device to which a light irradiation device according to the present embodiment is applied. FIG. 1 shows an X direction, a Y direction, and a Z direction. The X direction and the Y direction intersect with each other. For example, the X direction and the Y direction are orthogonal to each other. The Z direction intersects the X direction and the Y direction. For example, the Z direction is perpendicular to the X and Y directions. Below, the length in the X direction and the Y direction may be referred to as thickness or width. The length in the Z direction may also be referred to as thickness, depth, and height. Further, in the Z direction, the direction toward the tip of the arrow in the Z direction is sometimes referred to as an upward direction, the upper side, or the top, and the direction opposite to the upward direction is sometimes referred to as the downward direction, the lower side, or the bottom.

As shown in FIG. 1, the laser processing apparatus 10 includes a base 12, an XYZθ stage 14, a suction stage 16, a processing unit 18, a monitor 20, and a control device 22.

The base 12 has a horizontal surface, and an XYZθ stage 14 is provided on the base 12. The XYZθ stage 14 is provided on the base 12 so as to be movable in the XYZ directions and rotatable in the θ direction. This XYZθ stage 14 is moved in the XYZ directions and rotated in the θ direction by a moving mechanism (not shown) including an actuator, a motor, and the like.

The suction stage 16 is provided on the XYZθ stage 14 and holds the flat wafer W by suction. FIG. 2 is a plan view of the wafer W. As shown in FIG. 2, the wafer W is divided into a plurality of regions by a plurality of streets CH (also referred to as dividing lines) arranged in a grid, and each of the divided regions has various devices constituting semiconductor chips. 4 is formed. In this embodiment, a case will be described in which a wafer W is used as the workpiece, but the present invention is not limited to this, and for example, a glass substrate, a piezoelectric ceramic substrate, a glass substrate, etc. can also be applied. can.

The wafer W is placed on the suction stage 16 with a backgrind tape (hereinafter referred to as BG tape) having an adhesive material attached to the surface on which devices are formed (device surface), and the back surface facing upward. The thickness of the wafer W is not particularly limited, but is, for example, 700 μm or more or 700 μm to 800 μm.

Note that the wafer W may be placed on the suction stage 16 with a dicing tape having an adhesive material attached to one surface thereof and integrated with the frame via the dicing tape.

By moving the XYZθ stage 14 in the XYZθ directions by a moving mechanism (not shown), the processing unit 18 is moved relative to the wafer W on the suction stage 16 in the XYZθ directions. Thereby, the laser processing apparatus 10 forms a laser processing region inside the wafer W along the street CH.

The processing unit 18 includes a laser optical system 25 and an observation optical system 30. This processing unit 18 is arranged at a position above the suction stage 16 in the Z direction (a position facing the wafer W), and is controlled by a control device 22 .

The laser optical system 25 irradiates the streets CH on the wafer W with laser light L. This laser optical system 25 includes a laser light source 26 (laser oscillator), a collimating lens 27, a half mirror 28, and a condensing lens 29 (condensing lens).

The laser light source 26 emits processing laser light L (for example, pulsed laser light) for forming a laser processing region inside the wafer W toward the collimating lens 27 under the control of the control device 22 . The conditions for the laser beam L are, for example, that the light source is a semiconductor laser pumped Nd:YAG (Neodym: Yttrium Aluminum Garnet) laser, the wavelength is 1.1 μm, the cross-sectional area of the laser beam spot is 3.14×10 ⁻⁸ cm ² , The oscillation form is a Q-switch pulse, the repetition frequency is 80kHz to 200kHz, the pulse width is 180ns to 370ns, and the output is 8W.

The collimator lens 27 converts the laser beam L incident from the laser light source 26 into a parallel beam, and then emits the laser beam L toward the half mirror 28 .

The half mirror 28 is arranged on the optical axis of the condenser lens 29 and reflects a part of the laser beam L incident from the collimator lens 27 toward the condenser lens 29 . Further, the half mirror 28 transmits a part of the illumination light IL, which will be described later, that has entered from the half mirror 33, which will be described later, and outputs it toward the condenser lens 29, and the reflected light of the illumination light IL that has entered from the condenser lens 29. A part of the light passes through and is emitted toward the half mirror 33.

The condensing lens 29 condenses the laser beam L and/or the illumination light IL incident from the half mirror 28 onto the wafer W.

The observation optical system 30 is provided coaxially with the laser optical system 25. The observation optical system 30 aligns the wafer W before laser processing, and observes processing points (modified regions) formed within the wafer W after laser processing.

The observation optical system 30 includes a collimating lens 32, a half mirror 33, a condensing lens 34, an observation device 35, a light irradiation device 70, and the like. Furthermore, the observation optical system 30 shares a half mirror 28 and a condensing lens 29 with the laser optical system 25.

The light irradiation device 70 irradiates the collimator lens 32 with illumination light IL. The configuration of the light irradiation device 70 will be described later. The collimating lens 32 converts the illumination light IL incident from the light irradiation device 70 into a parallel light beam, and then emits the illumination light IL toward the half mirror 33 .

The half mirror 33 is arranged on the optical axis of the condenser lens 29 and reflects a part of the illumination light IL incident from the collimator lens 32 toward the half mirror 28 . Thereby, the illumination light IL is focused onto the surface of the wafer W via the half mirror 28 and the condensing lens 29. Further, the half mirror 33 transmits a part of the reflected light of the illumination light IL that has entered from the wafer W via the condenser lens 29 and the half mirror 28 and outputs the reflected light toward the condenser lens 34 .

The condenser lens 34 condenses the reflected light of the illumination light IL incident from the half mirror 33 onto the observation device 35 .

The observation device 35 is a so-called digital camera. Examples of the imaging device included in the observation device 35 include a CCD (Charged Coupled Device), a CMOS (Complementary Metal Oxide Semiconductor), and an InGaAs (Indium Gallium Arsenide) sensor. Note that the image sensor is not limited to this example, and any type of image sensor can be appropriately selected and used depending on the type of illumination light IL, the type of wafer W to be observed, the observation site, etc. .

The observation device 35 images the reflected light of the illumination light IL focused by the condenser lens 34 and outputs an observation image (captured image data) of each part of the wafer W to the control device 22 . The control device 22 displays on the monitor 20 an input/output screen regarding observation images and laser processing.

The control device 22 centrally controls the operation of each part of the laser processing apparatus 10 such as a moving mechanism (not shown), a laser optical system 25, and an observation optical system 30, and performs alignment of the processing unit 18, laser processing, Obtaining an observation image of the wafer W, etc. is performed.

The control device 22 is configured by an arithmetic device such as a personal computer, and includes an arithmetic circuit including various processors, memories, and the like. Various types of processors include, for example, CPUs (Central Processing Units), GPUs (Graphics Processing Units), ASICs (Application Specific Integrated Circuits), and programmable logic devices.Furthermore, programmable logic devices include, for example, SPLDs (Simple Programmable Logic Devices). ), CPLD (Complex Programmable Logic Device), and FPGA (Field Programmable Gate Arrays).The various functions of the control device 22 may be realized by one processor, or by multiple processors of the same or different types. It may be realized by a processor.

Next, the configuration of the light irradiation device 70 will be explained using FIG. 3. FIG. 3 is a functional block diagram of the light irradiation device 70. Note that FIG. 3 shows, as an example, a light irradiation device 70 that irradiates light through a connector 720 and an optical fiber 730. However, this example is not intended to limit the connection mode between the observation device 35 and the light irradiation device 70.

As shown in FIG. 3, the light irradiation device 70 includes a light bulb 701, a bandpass filter 702, a relative distance adjustment section (relative distance adjustment means) 703, a power supply 704, a shutter 705, a shutter drive section (shutter drive means) 706, a light amount It includes a control unit (light amount control means) 707, a housing 710, and an exit port 711. A light bulb 701, a bandpass filter 702, and a shutter 705 are provided inside a housing 710. The light emitting port 711 is a through hole formed in the casing 710, and the light from the light bulb 701 is emitted from the light emitting port 711 to the outside of the casing 710 as illumination light IL.

The light bulb 701 emits light using power supplied from a power source 704. The light bulb 701 is a so-called filament lamp having a filament. More specifically, for example, the light bulb 701 is a xenon arc lamp, a tungsten lamp, or a halogen lamp. When the observation device 35 is applied to the laser processing device 10, the light bulb 701 is particularly preferably a halogen lamp.

For example, during laser processing, the wafer W may be held on the XYZθ stage 14 so that the back surface (the surface opposite to the device surface) of the wafer W faces upward and faces the processing unit 18. In this case, when aligning the wafer W before laser processing or observing processing points (modified regions) formed in the wafer W after laser processing, the illumination light IL passes through the substrate and It is necessary to observe the inside of W.

Hereinafter, using FIG. 4, a light bulb 701 that can transmit through the substrate and allow good observation of the wafer W when the substrate of the wafer W is made of silicon will be described. FIG. 4 is a graph showing an example of the spectral distribution near the wavelength of light from the light bulb 701. In FIG. 4, the horizontal axis indicates the wavelength of light, and the unit is μm. The vertical axis shows the relative intensity of light. In addition, the solid line shows an example of the spectral distribution of a general halogen lamp, and the broken line shows a halogen lamp (Hisil 1500 manufactured by Kahoku Lighting Solutions Co., Ltd.) that has been improved so that the center wavelength is shifted to the infrared region compared to a general halogen lamp. ) shows an example of the spectral distribution of

When observing the wafer W through a silicon substrate, a light bulb 701 that can generate light with relatively high intensity in the infrared wavelength band is preferably used as shown in FIG. Note that this example is not intended to limit the light bulb 701. Naturally, the light bulb 701 can be appropriately selected depending on the material of the wafer W and the region to be observed.

Returning to FIG. 3, the bandpass filter 702 is provided near the light bulb 701 on the optical path between the light bulb 701 and the exit port 711. For example, when light from a light bulb 701 having a broadband spectral distribution as shown in FIG. 4 is used for observation, the observed image tends to be not very good. Therefore, in order to obtain a clearer observation image, the bandpass filter 702 selectively transmits light in a wavelength band suitable for observation among the broadband light emitted from the light bulb 701, and allows light in other bands to pass through. cut off.

For example, in the laser processing apparatus 10 shown in FIG. 1, when alignment is performed before processing with the wafer W held on the suction stage 16 with the surface (device surface) of the wafer W facing downward, and when alignment is performed before processing, the wafer When observing a laser processing region formed inside W, preferably, the bandpass filter 702 selectively transmits light in a specific wavelength band that can be transmitted through the substrate of the wafer W.

Using FIG. 5, as an example, when the substrate of the wafer W is made of silicon, a band that selectively transmits light having a wavelength that can pass through the substrate of the wafer W and allow good observation of the wafer W is shown. The transmission characteristics of the pass filter 702 will be explained. FIG. 5 is an example of a graph showing the transmission characteristics of the bandpass filter 702 (TS OD 4.0 25nm bandpass filter manufactured by Edmund Optics Co., Ltd., 1300nm 50nm, product code #87-841). In FIG. 5, the horizontal axis indicates the wavelength of light, and the unit is μm. The vertical axis indicates transmittance, and the unit is %. The bandpass filter 702 shown in FIG. 5 transmits infrared wavelength light having a center wavelength of 1.3 μm and a half width of 25 nm, and blocks other light. Thereby, light having characteristics suitable for observation can be emitted from the light irradiation device 70 as the illumination light IL. Naturally, the bandpass filter 702 can be appropriately selected depending on the spectral characteristics of the light bulb 701, the material of the wafer W, and the observation region.

Returning to FIG. 3, the relative distance adjustment section 703 includes a drive section (not shown) including a motor and a transmission mechanism. The relative distance adjustment section 703 adjusts the relative distance between the light bulb 701 and the emission aperture 711 by moving at least one of the light bulb 701 and the emission aperture 711 based on control by the light amount control section 707 . Here, when adjusting the relative distance between the light bulb 701 and the emission port 711, it is preferable that the relative distance adjustment section 703 does not change the positional relationship between the light bulb 701 and the bandpass filter 702 (described later). .

A shutter 705 blocks the light that has passed through the bandpass filter 702. The shutter drive unit 706 includes a drive unit (not shown) including a motor and a transmission mechanism. Based on the control by the light amount control unit 707, the shutter driving unit 706 moves the shutter 705 between an insertion position where the shutter 705 is inserted on the optical path between the light bulb 701 and the exit port 711 and a retracted position where the shutter 705 is retracted from the optical path. , selectively moves the shutter 705 forward and backward. The insertion position of the shutter 705 is preferably on the optical path between the light bulb 701 and the exit port 711, and near the exit port 711.

The illumination light IL emitted from the exit port 711 is irradiated toward the collimator lens 32 (see FIG. 1) via the connector 720 and the optical fiber 730. A user uses the observation device 35 to observe the wafer W irradiated with the illumination light IL. For example, when adjusting the brightness of the observed image, the user inputs an instruction to adjust the amount of illumination light IL to the light amount control section 707 via an input/output section (not shown).

The light amount control unit 707 performs control to adjust the light amount of the illumination light IL based on instructions output from the input/output unit. Specifically, the light amount control unit 707 performs control to adjust the light amount of the illumination light IL by changing the relative distance between the light bulb 701 and the exit port 711 using the relative distance adjustment unit 703. Further, the light amount control unit 707 controls the light amount of the illumination light IL to be 0 (zero) by moving the shutter 705 to the insertion position using the shutter drive unit 706. The principle of adjusting the amount of light by the light irradiation device 70 will be described in detail later.

Like the control device 22, the light amount control unit 707 is configured by a calculation device such as a personal computer, and includes a calculation circuit configured from various processors, memories, and the like. Since the example of the processor is as described above, the explanation will be omitted. Further, the light amount control unit 707 may be provided within the control device 22 or may be provided separately from the control device 22.

The light irradiation device 70 may further include a half mirror (not shown) provided near the emission port 711 and an illuminance sensor 712. The half mirror guides a portion of the illumination light IL emitted from the exit port 711 to the illuminance sensor 712 . The illuminance sensor 712 measures the amount of illumination light IL incident from the half mirror, and outputs (feeds back) the measurement result of the amount of light to the light amount controller 707 . The light amount control unit 707 can monitor whether the light amount is adjusted in accordance with the instruction output from the input/output unit based on the measurement result of the light amount.

Since the amount of illumination light IL emitted from the light irradiation device 70 is inversely proportional to the square of the relative distance between the light bulb 701 and the exit port 711, it tends to be difficult to linearly control the amount of light. However, by feeding back the measurement result of the light amount of the illumination light IL to the light amount control section 707, the light amount control section 707 can control the light amount more reliably.

Hereinafter, the principle of light amount adjustment by the light irradiation device 70 will be explained using FIG. 6. Reference numerals 6A to 6C in FIG. 6 indicate the positional relationships among the light bulb 701, bandpass filter 702, and shutter 705 in the casing 710 of the light irradiation device 70, respectively. 6A in FIG. 6 indicates a positional relationship when the amount of illumination light IL is large, 6B indicates a positional relationship when the amount of illumination light IL is small, and 6C indicates a positional relationship when the amount of illumination light IL is 0 (zero). ) shows the positional relationship in the case.

As shown by reference numeral 6A, when increasing the light intensity of the illumination light IL, the light irradiation device 70 moves the light bulb 701 using the relative distance adjustment unit 703 while keeping the voltage of the power supplied from the power source 704 constant. By doing so, the relative distance between the light bulb 701 and the emission aperture 711 is reduced. The amount of illumination light IL that passes through the exit port 711 is inversely proportional to the square of the distance between the light bulb 701 and the exit port 711, so by reducing the relative distance between the light bulb 701 and the exit port 711, the amount of illumination light IL can be reduced. can be increased.

On the other hand, as shown by reference numeral 6B, when reducing the light intensity of the illumination light IL, the light irradiation device 70 adjusts the light bulb by using the relative distance adjustment unit 703 while keeping the voltage of the power supplied from the power source 704 constant. By moving 701, the relative distance between light bulb 701 and emission aperture 711 is increased. This reduces the amount of illumination light IL. In this way, the light amount control unit 707 adjusts the amount of light by changing the relative distance between the light bulb 701 and the exit port 711 while keeping the voltage of the power supplied from the power source 704 constant.

In the conventional light irradiation device, the voltage of the power supplied to the light bulb 701 is changed in order to adjust the amount of light. At this time, since the amount of light changes non-linearly with respect to the voltage, a complicated circuit is required to adjust the voltage to set the desired amount of light. On the other hand, in the light irradiation device 70 of the present embodiment, the amount of light is adjusted by changing the relative distance between the light bulb 701 and the exit port 711 while keeping the voltage applied to the light bulb 701 constant. Such a complicated circuit becomes unnecessary.

Furthermore, in the conventional light irradiation device, since the voltage of the electric power supplied to the light bulb 701 is changed, the spectral distribution of the light from the light bulb 701 changes according to the change in voltage, so that illumination light having a desired wavelength can be emitted. , it is difficult to stably control the amount of light to obtain the desired amount of light. On the other hand, in the light irradiation device 70 of this embodiment, the light intensity of the illumination light IL can be adjusted while keeping the voltage of the power supplied to the light bulb 701 constant. Changes in the spectral distribution of light are suppressed. Therefore, in the light irradiation device 70, it is possible to perform more stable control than before so that illumination light having a desired wavelength and a desired amount of light can be obtained.

By the way, in halogen lamps, the life of the light bulb is extended due to the halogen cycle in which metal particles evaporated from the filament, which becomes hot when the lamp is lit, return to the filament. However, when a halogen lamp is used as a light bulb, conventional light irradiation devices reduce the voltage when reducing the amount of light, so this halogen cycle tends to be less likely to occur when the amount of light is low. In other words, when the amount of light is low, the metal particles evaporated from the filament do not return to the filament and are deposited on the glass surface of the light bulb 701, causing the filament to gradually become thinner, resulting in a problem that the life of the light bulb 701 is shortened.

On the other hand, in the light irradiation device 70 of the present embodiment, the amount of light can be adjusted while keeping the voltage applied to the light bulb 701 constant, so the halogen cycle can be maintained in a good condition. It becomes possible to suppress shortening of life. Note that, from the viewpoint of the lifespan of the light bulb 701, the voltage supplied to the light bulb 701 is preferably a voltage that allows the halogen cycle of the light bulb 701 to stably develop, for example.

Here, in the light irradiation device 70 of this embodiment, as shown by reference numerals 6A and 6B, when changing the relative distance between the light bulb 701 and the exit port 711 in order to adjust the amount of light, the light bulb 701 and the bandpass It is desirable to keep the positional relationship with the filter 702 constant. More specifically, for example, when configuring the relative distance adjustment section 703 to move the light bulb 701 in order to change the relative distance between the light bulb 701 and the light emitting port 711, the relative distance adjustment section 703 is configured to move the light bulb 701 together with the light bulb 701. The bandpass filter 702 is moved to . By keeping the positional relationship between the light bulb 701 and the bandpass filter 702 constant, fluctuations in the transmission characteristics of the bandpass filter 702 are suppressed, and the wavelength of the illumination light IL emitted from the light irradiation device 70 is stabilized. can be done. Thereby, the brightness of the observation image of the observation device 35 can be stably adjusted.

Hereinafter, the influence of temperature fluctuations on the bandpass filter 702 will be explained in more detail using FIG. 7. In the following description, it is assumed that the inside of the wafer W is observed using illumination light IL having an infrared wavelength. For example, when observing the inside of the wafer W using illumination light IL having a center wavelength of 1.3 μm and a half-width of 25 nm (see FIG. 5), the imaging device of the observation device 35 uses a near-infrared wavelength band. An InGaAs sensor having high sensitivity can be suitably used. FIG. 7 is a graph showing sensitivity changes in the near-infrared wavelength band of the InGaAs sensor. In FIG. 7, the horizontal axis indicates the wavelength of the illumination light IL, and the unit is μm. The vertical axis indicates the light receiving sensitivity of the InGaAs sensor, and the unit is A/W.

As shown in FIG. 7, the light-receiving sensitivity of the InGaAs sensor is not constant in the near-infrared wavelength band, and around the wavelength of 1.3 μm, the light-receiving sensitivity tends to increase as the wavelength increases. If the distance between the light bulb 701 and the bandpass filter 702 changes, the temperature of the bandpass filter 702 will also change. The transmission characteristics of the bandpass filter 702 tend to change depending on the temperature due to thermal expansion or contraction of the filter. Therefore, when the temperature of the bandpass filter 702 changes, the illumination light IL transmitted through the bandpass filter 702 changes. The wavelength of the light also tends to vary.

For example, in the case of the bandpass filter 702 having the characteristics shown in FIG. 5, when the temperature of the bandpass filter 702 increases, the wavelength of light transmitted through the bandpass filter 702 drifts toward longer wavelengths. Specifically, when the temperature of the bandpass filter 702 having the characteristics shown in FIG. 5 becomes 200° C. higher than the temperature during normal use, the center wavelength of the illumination light IL passing through the bandpass filter 702 becomes 1.3 μm. The length increases by approximately 0.01 μm from 1 to 1.31 μm (wavelength drift).

As shown in Figure 7, as the center wavelength changes, the light receiving sensitivity of the InGaAs sensor changes from about 0.67 A/W when the wavelength is 1.3 μm to about 0.67 A/W when the wavelength is about 1.31 μm. The light receiving sensitivity changes to approximately 0.69 A/W (sensitivity change). In this way, when the wavelength of the illumination light IL passing through the bandpass filter 702 changes, the brightness of the observed image of the observation device 35 changes due to a change in the light receiving sensitivity of the InGaAs sensor due to the change in wavelength. Even if the amount of light is adjusted, a problem may arise in that it is difficult to obtain an observed image with desired brightness.

In order to suppress such a problem, when changing the relative distance between the light bulb 701 and the exit port 711 to adjust the light intensity, by keeping the positional relationship between the light bulb 701 and the bandpass filter 702 constant, Fluctuations in the temperature of the bandpass filter 702 are suppressed, which in turn suppresses changes in the transmission characteristics of the bandpass filter 702. Thereby, it becomes possible to stably adjust the brightness of the observed image of the observation device 35.

Returning to FIG. 6, when the light intensity of the illumination light IL is set to 0 (zero), the light intensity control unit 707 causes the shutter drive unit 706 to move the shutter 705 between the light bulb 701 and the light emitting port 711, as shown by reference numeral 6C. Insert it onto the optical path. Since it is not necessary to turn off the light bulb 701 to make the light amount 0 (zero), the frequency of turning on and off the light bulb 701 during observation by the observation device 35 can be reduced. Furthermore, during observation using the observation device 35, it is possible to reduce the time required for so-called soft start for suppressing the rush current that occurs when turning on the illumination light IL. Further, by reducing the frequency of turning on and off the light bulb 701, shortening of the life of the light bulb 701 can also be suppressed.

<Others>
In the embodiment described above, the light irradiation device 70 and the observation device 35 are connected via the optical fiber 730, but instead of the optical fiber 730, a diaphragm may be provided near the exit port 711.

In the above embodiment, the laser processing apparatus 10 has been described as an example of a processing apparatus. Naturally, the light irradiation device 70 can also be applied to a blade dicing device or other processing devices.

In the above embodiment, the case where the inside of the wafer W is observed using infrared rays has been described as an example. Naturally, it is also possible to apply the light irradiation device 70 when observing the surface of the wafer W. In this case, it is possible to appropriately select a light bulb 701 and a bandpass filter 702 that have characteristics suitable for observation.

In the above embodiment, a case has been described in which the light irradiation device 70 is applied to the observation device 35 that observes the wafer W, but the observation target is not limited to the wafer W, as a matter of course.

<Effects of the invention>
As explained above, in the light irradiation device 70 of the present embodiment, the illumination light is emitted by changing the relative distance between the light bulb 701 and the exit port 711 while keeping the voltage applied to the light bulb 701 constant. Since the light amount of the IL is adjusted, a complicated circuit for adjusting the voltage of the power supplied to the light bulb 701 in order to adjust the light amount is not required. Furthermore, since the light intensity of the illumination light IL can be adjusted while keeping the voltage of the power supplied to the light bulb 701 constant, changes in the spectral distribution of the light from the light bulb 701 due to changes in voltage are suppressed. . Furthermore, it becomes possible to control the illumination light having the desired wavelength and the desired amount of light more stably than before.

In the light irradiation device 70 of this embodiment, when the light bulb 701 is a halogen lamp, the light intensity of the illumination light IL is adjusted while maintaining a constant voltage at which the halogen cycle of the light bulb 701 can stably develop. Thereby, shortening of the life of the light bulb 701 can be suppressed.

In the light irradiation device 70 of this embodiment, when changing the relative distance between the light bulb 701 and the light emitting port 711 in order to adjust the light intensity of the illumination light IL, the positional relationship between the light bulb 701 and the bandpass filter 702 is changed. Keep it constant. Thereby, changes in the transmission characteristics of the band-pass filter 702 due to temperature fluctuations of the band-pass filter 702 can be suppressed. Furthermore, since the wavelength of the illumination light IL emitted from the light irradiation device 70 can be stabilized, the brightness of the observed image of the observation device 35 can be stably adjusted.

In the light irradiation device 70 of this embodiment, when the light intensity of the illumination light IL is set to 0 (zero), the shutter 705 is inserted on the optical path between the light bulb 701 and the exit port 711. Thereby, the frequency of turning on and off the light bulb 701 during observation by the observation device 35 can be reduced. Furthermore, during observation using the observation device 35, it is possible to reduce the time required for soft start to suppress the rush current that occurs when lighting the light bulb 701. Further, by reducing the frequency of turning on and off the light bulb 701, shortening of the life of the light bulb 701 can also be suppressed.

Although the embodiments of the present invention have been described above, the present invention is not limited to the above examples, and it goes without saying that various improvements and modifications may be made without departing from the gist of the present invention. .

DESCRIPTION OF SYMBOLS 10... Laser processing device, 12... Base, 14... XYZθ stage, 16... Adsorption stage, 18... Processing unit, 20... Monitor, 22... Control device, 25... Laser optical system, 26... Laser light source, 27... Collimating lens, 28... Half mirror, 29... Condensing lens, 30... Observation optical system, 32... Collimating lens, 33... Half mirror, 34... Condensing lens, 35... Observation device, 70... Light irradiation device, 701... Light bulb, 702... Bandpass filter, 703... Relative distance adjustment unit, 704... Power supply, 705... Shutter, 706... Shutter drive unit, 707... Light amount control unit, 710... Housing, 711... Output port, 712... Illuminance sensor, 720... Connector, 730...Optical fiber, CH...Street, X, Y, Z...Axis direction, θ...Direction around Z axis, W...Wafer

Claims (4)

A light irradiation device provided in an observation device for observing a semiconductor wafer,
a light bulb having a filament;
a power source that supplies power to the light bulb;
a casing that houses the light bulb;
an output port provided in the housing and transmitting light emitted from the light bulb;
Relative distance adjustment means for changing the relative distance between the light bulb and the exit port;
light amount control means for controlling the amount of the light emitted from the exit port;
Equipped with
When changing the amount of light, the light amount control means changes the relative distance by the relative distance adjustment means while keeping the voltage of the electric power supplied from the power source constant.
Light irradiation device. a shutter that blocks the light;
shutter driving means for driving the shutter;
further comprising;
When setting the amount of light to zero, the light amount control means causes the shutter driving means to move the shutter onto an optical path between the light bulb and the exit port with the light bulb turned on.
The light irradiation device according to claim 1. Further comprising a bandpass filter that limits the wavelength band of the light between the light bulb and the exit port.
The light irradiation device according to claim 1 or 2. 4. The light irradiation device according to claim 3, wherein the relative distance adjusting means changes the relative distance while maintaining a constant positional relationship between the light bulb and the bandpass filter.

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