Detection method, image generation method, processing method, detection device, and processing device

Abstract

To be able to measure the inside of an object in air without submerging the object in water, and to not require a complex optical system such as a laser interferometer. [Solution] The processing method is a processing method for processing an object, and includes an elastic wave generating step 1002 for generating elastic waves from the back side of a second wafer of the object toward the front side of the second wafer, a measurement light irradiation step 1003 for irradiating a laser beam of a wavelength that is transparent to the object as measurement light toward the propagation region of the elastic wave, a signal light detection step 1004 for detecting signal light that is light reflected by the elastic wave from the laser beam that is measurement light after the measurement light irradiation step 1003, and a processing step 1008 for processing the object.

Description

[Technical Field]

[0001] The present invention relates to a detection method, an image generation method, a processing method, a detection device and a processing device. [Background technology]

[0002] It is known that an ultrasonic imaging device performs ultrasonic measurements while scanning an ultrasonic transmitting / receiving sensor along the surface of an object such as a semiconductor or integrated circuit placed underwater, thereby examining defects such as peeling and voids contained inside the object (see, for example, Patent Document 1).

[0003] The method described in Patent Document 1 requires the object to be submerged in water, and cannot be used in cases where the quality of the object deteriorates due to submersion in water.

[0004] Therefore, an ultrasonic measuring device has been proposed that can measure the inside of an object in the air without submerging the object in water (see, for example, Patent Document 2).

[0005] In the method described in Patent Document 2, ultrasonic waves are generated inside the object, and after propagating through the object, they are reflected or scattered by internal defects and then propagated back to the surface, where they are measured by a detection device such as a laser interferometer. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2021-143922 [Patent Document 2] Japanese Patent Application Publication No. 2022-174434 Summary of the Invention [Problem to be solved by the invention]

[0007] However, the method of Patent Document 2 requires the detection of minute surface vibrations caused by the propagation of ultrasonic waves to the surface, which requires a complex optical system such as a laser interferometer, resulting in a problem of the device becoming large and expensive.

[0008] The present invention has been made in consideration of such problems, and aims to propose a new measuring device that can measure the inside of an object in air without submerging the object in water, and that does not require a complex optical system such as a laser interferometer. [Means for solving the problem]

[0009] In order to solve the above-mentioned problems and achieve the object, the detection method of the present invention is a detection method for detecting the state of the inside of an object or the other side opposite to the one side from one side of the object, and is characterized by comprising an elastic wave generation step of generating elastic waves from the one side of the object toward the other side, a measurement light irradiation step of irradiating a laser beam of a wavelength that is transparent to the object as measurement light toward the elastic wave, and a signal light detection step of detecting signal light, which is light that is reflected by the elastic wave from the measurement light irradiation step, after the measurement light irradiation step.

[0010] In the detection method, the signal light detection step may detect the signal light generated during a period of time that is within a predetermined range from when the elastic wave was generated in the elastic wave generation step.

[0011] The detection method may further comprise a comparison step of comparing the frequency or wavelength of the signal light with that of the reference light, which is the measurement light that does not pass through the elastic wave.

[0012] In the detection method, the signal light detecting step may detect the signal light having a wavelength different from that of the measurement light.

[0013] In the detection method, the elastic wave generating step may generate the elastic wave by irradiating the one surface side of the object with a laser beam.

[0014] The image generation method of the present invention is an image generation method for generating an image of the inside of an object or the other side opposite to the one side from one side of the object, and is characterized by comprising an elastic wave generation step of generating elastic waves from the one side of the object toward the other side, a measurement light irradiation step of irradiating a laser beam of a wavelength that is transparent to the object as measurement light toward the elastic waves, a signal light detection step of detecting signal light, which is light that is reflected by the elastic wave from the measurement light after the measurement light irradiation step, and an image generation step of generating the image based on the intensity of the signal light.

[0015] The processing method of the present invention is a processing method for processing a workpiece, and is characterized by comprising an elastic wave generating step of generating elastic waves from one side of the workpiece toward the other side thereof, a measurement light irradiation step of irradiating a laser beam of a wavelength that is transparent to the workpiece as measurement light toward the propagation region of the elastic wave, a signal light detection step of detecting signal light, which is light that is reflected by the elastic wave from the measurement light after the measurement light irradiation step, and a processing step of processing the workpiece.

[0016] The detection device of the present invention is a detection device that detects the state of the inside of an object or the other side opposite to one side from one side of the object, and is characterized by comprising an elastic wave generating unit that generates elastic waves from one side of the object toward the other side, a measurement light irradiation unit that irradiates a laser beam of a wavelength that is transparent to the object toward the elastic wave as measurement light, and a signal light detection unit that detects signal light that is light reflected by the elastic wave from the measurement light.

[0017] The processing device of the present invention is a processing device for processing a workpiece, and comprises a holding unit for holding the workpiece, a processing unit for processing the workpiece, and a detection device for detecting the state of the inside of the workpiece or the other side opposite to the one side from one side of the workpiece, wherein the detection device comprises an elastic wave generating unit for generating elastic waves from the one side of the workpiece toward the other side, a measurement light irradiation unit for irradiating a laser beam of a wavelength that is transparent to the workpiece toward the elastic wave as measurement light, and a signal light detection unit for detecting signal light which is light reflected by the elastic wave from the measurement light. [Effects of the Invention]

[0018] The present invention has the advantage that it is possible to measure the inside of an object in air without submerging the object in water, and that a complex optical system such as a laser interferometer is not required. [Brief explanation of the drawings]

[0019] [Figure 1] FIG. 1 is a perspective view showing an example of the configuration of a processing apparatus according to the first embodiment. [Figure 2] FIG. 2 is a perspective view schematically showing an object to be processed by the processing apparatus shown in FIG. [Figure 3] FIG. 3 is a perspective view showing a schematic exploded view of the object shown in FIG. [Figure 4] FIG. 4 is a schematic diagram, partly in cross section, showing the configuration of a detection device of the processing apparatus shown in FIG. [Figure 5] FIG. 5 is a flowchart showing the flow of the processing method according to the first embodiment. [Figure 6] FIG. 6 is a side view, partially in cross section, schematically showing the elastic wave generating step and the measurement light irradiating step of the processing method shown in FIG. [Figure 7] FIG. 7 is another side view, partially in cross section, schematically illustrating the elastic wave generating step and the measurement light irradiating step of the processing method shown in FIG. [Figure 8]FIG. 8 is a side view, partly in section, schematically showing the signal light detection step of the processing method shown in FIG. [Figure 9] FIG. 9 is another side view, partly in section, schematically illustrating the signal light detection step of the processing method shown in FIG. [Figure 10] FIG. 10 is a diagram schematically illustrating the configuration of a detection device of the processing apparatus according to the second embodiment. [Figure 11] FIG. 11 is a cross-sectional view schematically showing an object to be processed by the processing apparatus and processing method according to the first modification. [Figure 12] FIG. 12 is a side view schematically showing processing steps of a processing method according to the second modification. DETAILED DESCRIPTION OF THE INVENTION

[0020] Modes (embodiments) for carrying out the present invention will be described in detail with reference to the drawings. The present invention is not limited to the contents described in the following embodiments. Furthermore, the components described below include those that can be easily imagined by a person skilled in the art and those that are substantially the same. Furthermore, the configurations described below can be combined as appropriate. Furthermore, various omissions, substitutions, or modifications of the configuration can be made within the scope of the gist of the present invention.

[0021] [Embodiment 1] A processing apparatus according to a first embodiment of the present invention will be described with reference to the drawings. Fig. 1 is a perspective view showing an example of the configuration of the processing apparatus according to the first embodiment. Fig. 2 is a perspective view schematically showing an object to be processed by the processing apparatus shown in Fig. 1. Fig. 3 is a perspective view schematically showing an exploded view of the object shown in Fig. 2.

[0022] (Object) The processing apparatus 1 shown in Fig. 1 according to the first embodiment is a laser processing apparatus that performs laser processing (corresponding to processing) on ​​an object 200 (corresponding to an object to be processed). The object 200 that is the processing target of the processing apparatus 1 according to the first embodiment is a stacked wafer formed by stacking a first wafer 201 and a second wafer 202, as shown in Figs. 2 and 3. In the first embodiment, the wafers 201 and 202 have substantially the same configuration, and therefore the same parts are denoted by the same reference numerals and description thereof will be omitted.

[0023] The wafers 201 and 202 are wafers such as disk-shaped semiconductor wafers with substrates made of silicon, GaAs, InP, GaN, SiC, or the like. As shown in Fig. 3, the wafers 201 and 202 have a surface 205 divided into regions in a lattice pattern by a plurality of intersecting planned division lines 206, and devices 207 are formed in each of the regions. The devices 207 are, for example, integrated circuits such as ICs (Integrated Circuits) or LSIs (Large Scale Integrations), or semiconductor memories (storage devices).

[0024] In the first embodiment, the object 200 is bonded such that the front surface 205 of the first wafer 201 and the front surface 205 of the second wafer 202 are bonded together. As a result, the device 207 formed on the first wafer 201 and the device 207 formed on the second wafer 202 are connected to each other.

[0025] In the present invention, the method for bonding the first wafer 201 and the second wafer 202 can be selected as appropriate. Specifically, the first wafer 201 and the second wafer 202 are bonded to each other by direct bonding or indirect bonding at their surfaces 205. For example, in embodiment 1, an adhesive is applied to the surface 205 side of the first wafer 201 or the surface 205 side of the second wafer 202, and the surface 205 of the first wafer 201 and the surface 205 of the second wafer 202 are bonded together via the adhesive.

[0026] For this reason, the target 200, which is a stacked wafer, has a bonding layer 203 made of an adhesive formed between surfaces 205 of the wafers 201 and 202. In addition, in the first embodiment, the target 200 is formed such that the wafers 201 and 202 are formed to have the same shape, and the devices 207 of the wafers 201 and 202 are stacked and bonded to each other.

[0027] Furthermore, in the present invention, there are no limitations on the material, shape, structure, size, etc. of the wafers 201, 202. The wafers 201, 202 may be substrates of any size and shape made of glass, ceramics, resin, metal, etc. Furthermore, there are no limitations on the type, number, shape, structure, size, arrangement, etc. of the devices 15 formed on the first wafer 201. Furthermore, in the present invention, a plurality of devices 207 may be formed on the surface 205 of the second wafer 202.

[0028] In the first embodiment, the object 200 is subjected to laser processing by adhering the center of a disk-shaped tape 210 having a larger diameter than the object 200 to a back surface 208 on the back side of the front surface 205 of a first wafer 201, and by adhering a ring-shaped frame 211 having an inner diameter larger than the outer diameter of the object 200 to the outer edge of the tape 210. Note that in the first embodiment, the back surface 208 on the back side of the front surface 205 of the second wafer 202 of the object 200 corresponds to one side of the object 200, and the front surface 205 of the second wafer 202 corresponds to the other side opposite to the one side (also referred to as the back side).

[0029] (Processing device) Next, we will explain the processing device 1. The processing device 1 is a laser processing device that irradiates a laser beam 21 onto an object 200 to form a modified layer along a planned dividing line 206 inside at least one of the substrates of wafers 201 and 202 of the object 200. As shown in FIG. 1 , the processing device 1 includes a holding unit 10, a moving unit 30, a laser beam irradiation unit 20, a detection device 50, and a controller 100.

[0030] The holding unit 10 is disk-shaped, and has a flat holding surface 11 formed of porous ceramic or the like along the horizontal direction for holding the object 200. The holding unit 10 is also provided so as to be movable by a moving unit 30 between a processing area below the laser beam irradiation unit 20 and a carry-in / out area spaced from below the laser beam irradiation unit 20 where the object 200 is carried in and out.

[0031] The holding unit 10 is connected to a vacuum suction source (not shown), and is sucked by the vacuum suction source to suck and hold the object 200 placed on the holding surface 11. In the first embodiment, the holding unit 10 sucks and holds the back surface 208 of the first wafer 201 of the object 200 via a tape 210 attached to the back surface 208 of the first wafer 201 of the object 200.

[0032] The moving unit 30 moves the holding unit 10 and the laser beam irradiation unit 20 relatively. The moving unit 30 includes a Y-axis moving unit 31, which is an indexing feed unit that moves the holding unit 10 in the Y-axis direction parallel to the horizontal direction, an X-axis moving unit 32, which is a processing feed unit that moves the holding unit 10 in the X-axis direction parallel to the horizontal direction and perpendicular to the Y-axis direction, and a rotational moving unit 33 that rotates the holding unit 10 around an axis parallel to the Z-axis direction that is perpendicular to both the X-axis and Y-axis directions and parallel to the vertical direction.

[0033] The Y-axis movement unit 31 is installed on the apparatus main body 2, and moves the moving plate 3 on which the X-axis movement unit 32 is installed in the Y-axis direction, thereby moving the holding unit 10 in the Y-axis direction. The X-axis movement unit 32 is installed on the moving plate 3, and moves the second moving plate 4 on which the rotational movement unit 33 is installed in the X-axis direction, thereby moving the holding unit 10 in the X-axis direction. The rotational movement unit 33 is installed on the second moving plate 4, and supports the holding unit 10, thereby rotating the holding unit 10 around its axis.

[0034] The Y-axis moving unit 31 moves the moving plate 3, the X-axis moving unit 32, the second moving plate 4, the rotational moving unit 33, and the holding unit 10 in the Y-axis direction. The X-axis moving unit 32 moves the second moving plate 4, the rotational moving unit 33, and the holding unit 10 in the X-axis direction.

[0035] The Y-axis moving unit 31 and the X-axis moving unit 32 each include a well-known ball screw rotatably mounted about its axis, a well-known motor for rotating the ball screw about its axis, and a well-known guide rail for supporting the moving plates 3 and 4 movably in the Y-axis direction or the X-axis direction. The rotational moving unit 33 includes a well-known motor for rotating the holding unit 10 about its axis.

[0036] 1, the laser beam irradiation unit 20 is partially provided at the tip of a support column 6 whose base end is fixed to an erect wall 5 erected from the end of the device body 2 in the Y-axis direction. The laser beam irradiation unit 20 is a processing unit that irradiates a laser beam 21 onto an object 200 held by the holding unit 10 to perform laser processing (corresponding to processing).

[0037] In embodiment 1, the laser beam irradiation unit 20 includes a laser oscillator 22 that emits a laser beam 21 having a wavelength that is transparent to the object 200, a focusing lens 23 (corresponding to a focusing device) that focuses the laser beam 21 inside the object 200 held by the holding unit 10, and a reflecting mirror 24 that reflects the laser beam 21 emitted by the laser oscillator 22 toward the focusing lens 23.

[0038] In the first embodiment, the laser beam irradiation unit 20 sets a focal point of a laser beam 21, which is transparent to the object 200, inside the substrate of at least one of the wafers 201 and 202 of the object 200, and irradiates the laser beam 21 along the planned dividing line 206 to form a modified layer inside at least one of the wafers 201 and 202 of the object 200. The modified layer refers to a region where the density, refractive index, mechanical strength, and other physical properties are different from those of the surrounding area, and examples of the modified layer include a melt-processed region, a cracked region, a dielectric breakdown region, a refractive index change region, and a region where these regions are mixed. The modified layer also has lower mechanical strength and the like than other parts of the wafers 201 and 202 of the object 200.

[0039] (Detection device) Next, the detection device 50 will be described. FIG. 4 is a diagram schematically illustrating, in partial cross section, the configuration of the detection device of the processing apparatus shown in FIG. 1. The detection device 50 is a device that detects the state of the inside of the object 200 or the state of the front surface 205 side of the second wafer 202 opposite to the back surface 208 side from the back surface 208 side of the second wafer 202 of the object 200. In the first embodiment, the detection device 50 detects defects 204 such as voids between the second wafer 202 and the first wafer 201 of the object 200, i.e., defects 204 in the bonding layer 203, and detects the positions of devices 207 and planned dividing lines 206 on the wafers 201 and 202 to acquire images for performing alignment between the object 200 and the laser beam irradiation unit 20, etc.

[0040] The detection device 50 is installed at the tip of the support column 6, and is arranged in a position aligned in the X-axis direction with the condenser lens 23 of the laser beam irradiation unit 20. As shown in Fig. 4, the detection device 50 includes an elastic wave generating unit 51, a measurement light irradiation unit 60, and a signal light detection unit 70. Note that the object 200 shown in Fig. 4 shows a cross section of the bonding layer 203 and the side surfaces of the wafers 201 and 202.

[0041] The elastic wave generating unit 51 generates an elastic wave 220 inside the object 200 held in the holding unit 10 from the back surface 208 toward the front surface 205 of the second wafer 202 of the object 200. In the first embodiment, as shown in FIG. 4 , the elastic wave generating unit 51 irradiates a predetermined location on the back surface 208 of the second wafer 202 of the object 200 held in the holding unit 10 with a laser beam 52 having a wavelength that generates an elastic wave 220 at least inside the second wafer 202 of the object 200. The optical axis of the laser beam 52 irradiated by the elastic wave generating unit 51 onto the object 200 is inclined with respect to both the back surface 208 of the second wafer 202 of the object 200 and the Z-axis direction perpendicular to the back surface 208. Note that in the present invention, the laser beam 52 may be irradiated coaxially with the measurement light 61 without tilting the optical axis of the laser beam 52 irradiated by the elastic wave generating unit 51 onto the object 200.

[0042] 4, i.e., between the back surface 208 and the front surface 205 of the second wafer 202. In the first embodiment, the acoustic impedance of the device 207 is different from that of the planned dividing line 206. Therefore, in the first embodiment, the acoustic impedance of the device 207 is different from that of the planned dividing line 206. Therefore, in the first embodiment, the acoustic impedance of the device 207 is different from that of the planned dividing line 206. In the first embodiment, the acoustic impedance of the device 207 is different from that of the planned dividing line 206. In the second embodiment, the acoustic impedance of the device 207 is different from that of the planned dividing line 206. In the first embodiment, the acoustic impedance of the device 207 is different from that of the planned dividing line 206. In the second embodiment, the acoustic impedance of the device 207 is different from that of the planned dividing line 206. In the second embodiment, the acoustic impedance of the device 207 is different from that of the planned dividing line 206. In the second embodiment, the acoustic impedance of the device 207 is different from that of the planned dividing line 206. In the first embodiment, the acoustic impedance of the device 207 is different from that of the planned dividing line 206. In this case, when the acoustic impedance of the device 207 is different from that of the planned dividing line 206, the acoustic wave 220 reflected by the device 207 has a different intensity from that of the planned dividing line 206. In the second embodiment, the acoustic impedance of the device 207 is different ... For the same reason, the intensity of the elastic waves 220 reflected from defects 204 such as voids also differs, and generally, the elastic waves 220 reflected from defects 204 such as voids have a greater intensity than the elastic waves 220 reflected from the device 207 and the elastic waves 220 reflected from the planned division line 206.

[0043] The measurement light irradiation unit 60 irradiates a laser beam 62 having a wavelength that is transparent to the object 200 as measurement light 61 toward an elastic wave 220 generated inside the second wafer 202 of the object 200. As shown in Fig. 4, the measurement light irradiation unit 60 includes a laser diode 63 that emits a laser beam 62 having a wavelength that is transparent to the second wafer 202 of the object 200 as measurement light 61, photocouplers 64 and 65, and an irradiation head 66 that irradiates the laser beam 62 as measurement light 61 toward the back surface 208 of the second wafer 202 of the object 200 held by the holding unit 10.

[0044] The photocouplers 64 and 65 are disposed between the laser diode 63 and the irradiation head 66. The photocoupler 64 closer to the laser diode 63 branches the laser beam 62, which is the measurement light 61 emitted by the laser diode 63, and emits the branched laser beam 62 toward the irradiation head 66 and the signal light detection unit 70.

[0045] The photocoupler 65 closer to the irradiation head 66 emits a laser beam 62, which is one of the measurement beams 61 branched by the photocoupler 64, toward the irradiation head 66. The photocoupler 65 closer to the irradiation head 66 emits signal beam 67, which is light (laser beam) reflected by an elastic wave 220 generated inside the second wafer 202 of the object 200 of the laser beam 62, which is the measurement beam 61, toward the signal beam detection unit 70.

[0046] The signal light 67 is light generated when the laser beam 62, which is the measurement light 61, is reflected by the elastic wave 220. The intensity of the signal light 67 increases as the intensity (amplitude) of the elastic wave 220 increases.

[0047] The irradiation head 66 faces the holding surface 11 of the holding unit 10 positioned in the processing area in the Z-axis direction perpendicular to the holding surface 11. The irradiation head 66 irradiates a laser beam 62, which is measurement light 61, along the Z-axis direction at the same position on the back surface 208 of the second wafer 202 of the object 200 held on the holding surface 11 of the holding unit 10 positioned in the processing area where the elastic wave generating unit 51 irradiates with the laser beam 52. The irradiation head 66 receives signal light 67, which is light (laser beam) reflected by elastic waves 220 generated inside the second wafer 202 of the object 200 of the laser beam 62, which is measurement light 61, and emits it toward the photocoupler 65.

[0048] The optical axis of the laser beam 62 that the irradiation head 66, i.e., the measurement light irradiation unit 60 irradiates onto the object 200 as the measurement light 61, is parallel to the Z-axis direction that is perpendicular to the back surface 208 of the second wafer 202 of the object 200.

[0049] In the first embodiment, the measuring light irradiation unit 60 described above irradiates a laser beam 62, which is the measuring light 61, onto the same position of the object 200 held by the holding unit 10 as the position at which the elastic wave generating unit 51 irradiates the laser beam 52. In the first embodiment, the measuring light irradiation unit 60 irradiates the object 200 with the laser beam 62, which is the measuring light 61, at the same time that the elastic wave generating unit 51 irradiates the object 200 with the laser beam 52.

[0050] The signal light detection unit 70 detects signal light 67, which is light that is formed when the laser beam 62, which is the measurement light 61, is reflected by an elastic wave 220 generated inside the second wafer 202 of the object 200. In the first embodiment, the signal light detection unit 70 includes a photocoupler 71 and a differential amplification photodetector 72.

[0051] The photocoupler 71 receives the laser beam 62, which is the other measuring light 61 branched by the photocoupler 64, and the signal light 67 from the photocoupler 65. The photocoupler 71 outputs the laser beam 62, which is the measuring light 61, and the signal light 67 to the differential amplification photodetector 72.

[0052] When the measurement light 61 is reflected by the moving elastic wave 220, a phenomenon called Doppler shift occurs, in which the frequency of the reflected light (signal light 67) changes depending on the relative speed between the measurement light 61 and the elastic wave 220. Therefore, the measurement light 61, the signal light 67 reflected by the elastic wave 220 moving in the direction from the front surface 205 to the back surface 208 (after being reflected at the interface), and the signal light 67 reflected by the elastic wave 220 moving in the direction from the back surface 208 to the front surface 205 have different frequencies. When the above phenomenon occurs, the differential amplification photodetector 72 causes interference between the laser beam 62, which is the incident measurement light 61, and the signal light 67, thereby generating an optical beat (also called a waviness), and detects the intensity of the signal light 67 reflected by the elastic wave 220, which is reflected at the interface between the wafer 202 and the bonding layer 203 and travels back and forth in the thickness direction, in the direction from the front surface 205 to the back surface 208 of the second wafer 202, and outputs the detected intensity of the signal light 67 to the controller 100. When the thickness of the second wafer 202 is L and the speed of sound within the second wafer 202 is v, the differential amplification photodetector 72 detects the intensity of the signal light 67 reflected by the elastic wave 220 within a predetermined time before and after time t that satisfies the following equation 1:

[0053]

number

[0054] The differential amplification photodetector 72 detects the intensity of the signal light 67 reflected by the elastic wave 220 within a predetermined time before and after the time t that satisfies Equation 1, thereby detecting the intensity of the signal light 67 reflected by the elastic wave 220 that is reflected at the interface between the wafer 202 and the bonding layer 203 and travels from the front surface 205 to the back surface 208 of the wafer 202, among the elastic waves 220 that travel back and forth in the thickness direction. Note that the time t is the elapsed time after the elastic wave generating unit 51 and the measurement light irradiating unit 60 irradiate the laser beams 52 and 62.

[0055] In this way, the differential amplification photodetector 72 detects the intensity of the signal light 67 reflected by the elastic wave 220 within a predetermined time before and after the time t that satisfies Equation 1, thereby detecting the signal light 67 generated during a period in which the elapsed time from when the elastic wave generating unit 51 generated the elastic wave 220 inside the second wafer 202 of the object 200 is within a predetermined range. Furthermore, the differential amplification photodetector 72 causes interference between the laser beam 62, which is the incident measurement light 61, and the signal light 67, thereby generating an optical beat (also called a swell), and detects the intensity of the signal light 67 reflected by the elastic wave 220, thereby comparing the frequency or wavelength of the signal light 67 with that of the laser beam 62 (corresponding to reference light), which is the measurement light 61 that does not pass through the elastic wave 220, i.e., is not reflected by the elastic wave 220.

[0056] In the first embodiment, the wavelength λ of the laser beam 62, which is the measurement light 61 irradiated by the measurement light irradiating unit 60 of the detection device 50, the elastic wave frequency Λ of the elastic wave 220 generated inside the second wafer 202 of the object 200, and the frequency f of the laser beam 52 irradiated by the elastic wave generating unit 51 satisfy the following formulas 2 and 3, where N is a natural number and θ is the angle between the optical axis of the laser beam 62, which is the measurement light 61, and the back surface 208 of the second wafer 202 of the object 200. Thus, the laser beam 52, which generates the elastic wave 220 generated inside the second wafer 202 of the object 200, and the laser beam 62, which is the measurement light 61, satisfy the Bragg condition. Note that v in the following formula 3 is the speed of sound inside the second wafer 202 of the object 200.

[0057]

number

[0058]

number

[0059] In the first embodiment, when N=1, the angle θ is 90 degrees, and the second wafer 202 is made of silicon, the internal sound speed v is 9620 m / sec. Therefore, when the wavelength λ of the laser beam 62, which is the measurement light 61, is 1100 nm, the frequency f of the laser beam 52 irradiated by the elastic wave generating unit 51 is 17.5 GHz.

[0060] As described above, in the first embodiment, the wavelength λ of the laser beam 62 serving as the measurement light 61, the sound speed v within the second wafer 202, which is irradiated with the laser beam 52 of the object 200 and generates an elastic wave 220 therein, and the frequency f of the laser beam 52 irradiated by the elastic wave generating unit 51 satisfy the following formula 4. In the first embodiment, the wavelength λ of the laser beam 62 serving as the measurement light 61, the sound speed v within the second wafer 202, which is irradiated with the laser beam 52 of the object 200 and generates an elastic wave 220 therein, and the frequency f of the laser beam 52 irradiated by the elastic wave generating unit 51 satisfy the following formula 4, so that the elastic wave 220 and the laser beam 62 serving as the measurement light 61 satisfy the Bragg condition, and the intensity (amplitude) of the signal light 67 is made larger than when the Bragg condition is not satisfied.

[0061]

number

[0062] However, in the present invention, it is desirable that the wavelength λ of the laser beam 62, which is the measurement light 61, the speed of sound v within the second wafer 202, which is irradiated with the laser beam 52 of the object 200 and generates an elastic wave 220 therein, and the frequency f of the laser beam 52 irradiated by the elastic wave generating unit 51, are set so that they satisfy the following equation 5:

[0063]

number

[0064] When the difference between the wavelength λ of the laser beam 62 serving as the measurement light 61 and twice the value obtained by dividing the sound speed v by the frequency f exceeds 10% of the wavelength λ of the laser beam 62 serving as the measurement light 61, the intensity (amplitude) of the signal light 67 cannot be set to an intensity (amplitude) that can detect defects 204 such as voids between the second wafer 202 and the first wafer 201 of the object 200, i.e., defects 204 in the bonding layer 203. When the difference between the wavelength λ of the laser beam 62 serving as the measurement light 61 and twice the value obtained by dividing the sound speed v by the frequency f is 10% or less of the wavelength λ of the laser beam 62 serving as the measurement light 61, the intensity (amplitude) of the signal light 67 can be set to an intensity (amplitude) that can detect defects 204 such as voids between the second wafer 202 and the first wafer 201 of the object 200, i.e., defects 204 in the bonding layer 203. In any case, in the present invention, the wavelength λ of the laser beam 62, which is the measurement light 61, and the frequency f of the laser beam 52 irradiated by the elastic wave generating unit 51 are appropriately selected according to the intensity of the signal light 67 required for measurement.

[0065] The controller 100 controls each component of the processing device 1 to cause the processing device 1 to perform a processing operation on the target object 200. The controller 100 is a computer having an arithmetic processing device with a microprocessor such as a CPU (central processing unit), a storage device with memory such as a ROM (read only memory) or RAM (random access memory), and an input / output interface device. The arithmetic processing device of the controller 100 performs arithmetic processing in accordance with a computer program stored in the storage device, and outputs control signals for controlling the processing device 1 to each component of the processing device 1 via the input / output interface device.

[0066] The controller 100 is connected to a display unit (not shown) configured with a liquid crystal display device or the like that displays the status and images of the machining operation, an input unit (not shown) that the operator uses to register processing conditions, and an alarm unit that notifies the operator. The input unit is configured with at least one of a touch panel provided on the display unit and an external input device such as a keyboard. The alarm unit emits at least one of sound and light to notify the operator.

[0067] (Processing method) Next, a processing method according to embodiment 1 will be described. Fig. 5 is a flowchart showing the flow of the processing method according to embodiment 1. The processing method according to embodiment 1 is a method of performing laser processing on the object 200 using the processing device 1 having the above-described configuration. In other words, the processing method is also a method in which the processing device 1 having the above-described configuration forms a modified layer along the planned dividing line 206 inside at least one of the wafers 201, 202 of the object 200.

[0068] As shown in FIG. 5, the processing method according to the first embodiment includes a holding step 1001, an elastic wave generating step 1002, a measurement light irradiating step 1003, a signal light detecting step 1004, a signal light processing step 1006, and a processing step 1008.

[0069] (holding step) The holding step 1001 is a step of holding the object 200 in the holding unit 10. In the first embodiment, in the holding step 1001, the processing conditions are registered in the controller 100 by an operator or the like, and the back surface 208 side of the first wafer 201 of the object 200 is placed on the holding surface 11 of the holding unit 10 via the tape 210 in the air. In the first embodiment, in the holding step 1001, when the controller 100 receives an instruction to start a processing operation from an operator or the like, the controller 100 suction-holds the back surface 208 side of the first wafer 201 of the object 200 on the holding surface 11 of the holding unit 10 via the tape 210 in the air.

[0070] (Elastic wave generation step and measurement light irradiation step) Fig. 6 is a side view, partially in cross section, schematically illustrating the elastic wave generating step and the measurement light irradiating step of the processing method shown in Fig. 5. Fig. 7 is another side view, partially in cross section, schematically illustrating the elastic wave generating step and the measurement light irradiating step of the processing method shown in Fig. 5. Note that the object 200 shown in Figs. 6 and 7 shows a cross section of the bonding layer 203 and the side surfaces of the wafers 201 and 202.

[0071] The elastic wave generating step 1002 is a step of generating an elastic wave 220 from the back surface 208 side of the second wafer 202 of the object 200 toward the front surface 205 side of the second wafer 202. The measurement light irradiating step 1003 is a step of irradiating a laser beam 62 having a wavelength that is transparent to the object 200 as measurement light 61 toward the propagation region of the elastic wave 220 (a position overlapping with the elastic wave 220 in the thickness direction).

[0072] In the first embodiment, the elastic wave generating step 1002 and the measurement light irradiating step 1003 are started simultaneously. In the first embodiment, in the elastic wave generating step 1002 and the measurement light irradiating step 1003, the processing device 1 has the controller 100 control the moving unit 30 to move the holding unit 10 toward the processing area and position the detection device 50 directly above the position where the laser beams 52, 62 are first irradiated on the back surface 208 of the second wafer 202 of the target object 200, as determined by the processing conditions.

[0073] In embodiment 1, in the elastic wave generating step 1002 and the measurement light irradiating step 1003, the processing device 1 has the controller 100 position the detection device 50 and simultaneously start irradiating the laser beams 52 and 62 to the position on the back surface 208 of the second wafer 202 of the object 200 where the laser beams 52 and 62 are to be initially irradiated, as shown in FIG. 6, and as shown in FIG. 7, stop irradiating the laser beam 52 after a predetermined time has elapsed since the start of irradiation, and stop irradiating the laser beam 62 after a second predetermined time that is longer than the predetermined time and time t from the start of irradiation.

[0074] 6 and 7, in the elastic wave generating step 1002, an elastic wave 220 is generated inside the second wafer 202 of the object 200 at a position that overlaps in the Z-axis direction with the position irradiated with the laser beam 52 on the second wafer 202 of the object 200 held in the holding unit 10. Thus, in the elastic wave generating step 1002 in the first embodiment, the laser beam 52 is irradiated onto the back surface 208 side of the second wafer 202 of the object 200, thereby generating an elastic wave 220 inside the second wafer 202 of the object 200.

[0075] 6 and 7, in the measurement light irradiation step 1003, the laser beam 62, which is the measurement light 61 irradiated from the irradiation head 66, is reflected by the elastic wave 220 and received by the irradiation head 66 as signal light 67. Also, in the measurement light irradiation step 1003, the signal light 67 and the laser beam 62, which is the other measurement light 61 branched by the photocoupler 64, are received by the differential amplification photodetector 72 of the signal light detection unit 70.

[0076] (Signal light detection step) Fig. 8 is a side view, partially in cross section, schematically illustrating the signal light detection step of the processing method shown in Fig. 5. Fig. 9 is another side view, partially in cross section, schematically illustrating the signal light detection step of the processing method shown in Fig. 5. Note that the object 200 shown in Figs. 8 and 9 shows a cross section of the bonding layer 203 and the side surfaces of the wafers 201 and 202. The signal light detection step 1004 is a step of detecting the signal light 67, which is light resulting from reflection of the laser beam 62, which is the measurement light 61, by the elastic wave 220, after the measurement light irradiation step 1003.

[0077] In the first embodiment, in the signal light detection step 1004, the differential amplification photodetector 72 of the signal light detection unit 70 of the processing device 1 causes interference between the laser beam 62, which is the measurement light 61 incident from the photocoupler 71, and the signal light 67, thereby generating an optical beat (also called a waviness), and detects the intensity of the signal light 67 reflected by the elastic wave 220 that moves back and forth in the thickness direction and is reflected at the interface between the wafer 202 and the bonding layer 203 and moves from the position shown in Fig. 8 to the position shown in Fig. 9, i.e., from the front surface 205 to the back surface 208 of the wafer 202, and outputs the detected intensity of the signal light 67 to the controller 100. Thus, the signal light detection step 1004 is a comparison step in which the frequency or wavelength of the signal light 67 is compared with that of the laser beam 62 (corresponding to the reference light), which is the measurement light 61 that does not pass through the elastic wave 220.

[0078] Furthermore, in the first embodiment, in the signal light detecting step 1004, the differential amplification photodetector 72 of the signal light detecting unit 70 of the processing device 1 detects the intensity of the signal light 67 reflected by the elastic wave 220 within a predetermined time before and after the time t that satisfies the above-described formula 1. Thus, in the signal light detecting step 1004, the signal light 67 generated during a period in which the elapsed time from the generation of the elastic wave 220 in the elastic wave generating step 1002 is within a predetermined range is detected.

[0079] Furthermore, in the signal light detection step 1004, the differential amplification photodetector 72 detects the intensity of the signal light 67 reflected by the elastic waves 220 that travel back and forth in the thickness direction and are reflected at the interface between the wafer 202 and the bonding layer 203 and move in a direction from the front surface 205 toward the back surface 208 of the second wafer 202, thereby detecting the state of the inside of the second wafer 202 of the object 200 or the front surface 205 side opposite to the back surface 208 side from the back surface 208 side of the second wafer 202 of the object 200. As described above, in the first embodiment, the elastic wave generation step 1002, the measurement light irradiation step 1003, and the signal light detection step 1004 constitute a detection method for detecting the state of the inside of the second wafer 202 of the object 200 or the front surface 205 side opposite to the back surface 208 side from the back surface 208 side of the second wafer 202 of the object 200.

[0080] After the signal light detection step 1004, the processing device 1 determines whether the controller 100 has detected the intensity of the signal light 67 over the entire surface of the back surface 208 of the second wafer 202 of the object 200 at a predetermined distance determined by the processing conditions (step 1005). If the processing device 1 determines that the controller 100 has not detected the intensity of the signal light 67 over the entire surface of the back surface 208 of the second wafer 202 of the object 200 (step 1005: No), the processing device 1 returns to the elastic wave generation step 1002 and the measurement light irradiation step 1003.

[0081] In the returned elastic wave generating step 1002 and the measurement light irradiating step 1003, the processing device 1 has the controller 100 control the moving unit 30 to relatively move the object 200 held by the holding unit 10 and the detection device 50 in the horizontal direction by the aforementioned predetermined distance, and then irradiates the laser beams 52, 62 onto the back surface 208 of the second wafer 202 of the object 200 as before. In the signal light detecting step 1004 after the returned elastic wave generating step 1002 and the measurement light irradiating step 1003, the processing device 1 has the differential amplification photodetector 72 of the signal light detecting unit 70 detect the intensity of the signal light 67 as before, and output the detection result to the controller 100.

[0082] When the controller 100 determines that the intensity of the signal light 67 has been detected over the entire surface of the back surface 208 of the second wafer 202 of the object 200 (step 1005: Yes), the processing device 1 proceeds to signal light processing step 1006.

[0083] (Signal light processing step) The signal light processing step 1006 is a step of processing the signal light 67 detected in the signal light detection step 1004. In the first embodiment, in the signal light processing step 1006, the controller 100 of the processing device 1 generates an image of the front surface 205 side of the second wafer 202 based on the intensity of the signal light 67 at a predetermined distance. Note that in the first embodiment, in the signal light processing step 1006, the controller 100 of the processing device 1 generates an image of different aspects depending on the intensity of the signal light 67. For example, an image is generated in which each position where the intensity of the signal light 67 is detected is brightened as the intensity of the signal light 67 increases, or a predetermined color is made darker as the intensity of the signal light 67 increases.

[0084] Since the intensity of the signal light 67 differs between the devices 207 and the planned dividing lines 206, the generated image makes it possible to detect the positions of the devices 207 and the planned dividing lines 206 of the second wafer 202. Thus, in the first embodiment, the signal light processing step 1006 is an image generating step of generating an image based on the intensity of the signal light 67. In the first embodiment, by generating an image based on the intensity of the signal light 67 in the signal light processing step 1006, the elastic wave generating step 1002, the measurement light irradiating step 1003, the signal light detecting step 1004, and the signal light processing step 1006 constitute an image generating method of generating an image of the inside of the second wafer 202 of the object 200 or the front surface 205 side opposite to the back surface 208 side of the second wafer 202 of the object 200 from the back surface 208 side of the second wafer 202.

[0085] In the first embodiment, in the signal light processing step 1006, the controller 100 of the processing device 1 determines whether or not any of the intensities of the signal light 67 at a predetermined distance is equal to or greater than a predetermined intensity, and determines whether or not there is an abnormality on the surface 205 of the second wafer 202 (step 1007). Note that the predetermined intensity is the value of the intensity of the signal light 67 when there is a defect 204 such as a void in the bonding layer 203.

[0086] In the first embodiment, in the signal light processing step 1006, if the controller 100 determines that any of the intensities of the signal light 67 at a predetermined distance is equal to or greater than a predetermined intensity, the processing device 1 determines that there is an abnormality in the surface 205 of the second wafer 202 (step 1007: Yes), activates the alarm unit to notify the operator, and ends the processing method. In the first embodiment, in the signal light processing step 1006, if the controller 100 determines that there is no of the intensities of the signal light 67 at a predetermined distance is equal to or greater than a predetermined intensity, the processing device 1 determines that there is no abnormality in the surface 205 of the second wafer 202 (step 1007: No), and proceeds to processing step 1008.

[0087] (Processing Steps) Processing step 1008 is a step of processing the object 200. In the first embodiment, in processing step 1008, the processing device 1 causes the controller 100 to detect the planned division line 206 from the image generated in the signal light processing step 1006, and controls the moving unit 30 to perform alignment of the object 200 with the laser beam irradiation unit 20.

[0088] In embodiment 1, in processing step 1008, the processing device 1 has the controller 100 control the laser beam irradiation unit 20 and the moving unit 30 to relatively move the focusing lens 23 of the laser beam irradiation unit 20 and the holding unit 10 along the planned division line 206, thereby positioning the focusing point of the laser beam 21 inside the object 200 and irradiating the laser beam 21.

[0089] In embodiment 1, in processing step 1008, the laser beam 21 has a wavelength that is transparent to the object 200, so that a modified layer is formed inside the object 200 along the planned dividing lines 206. In embodiment 1, in processing step 1008, the processing device 1 forms a modified layer inside at least one of the first wafer 201 and the second wafer 202 of the object 200 along all of the planned dividing lines 206. In embodiment 1, in processing step 1008, the processing device 1 ends the processing method when it has formed a modified layer inside at least one of the first wafer 201 and the second wafer 202 of the object 200 along all of the planned dividing lines 206.

[0090] As described above, the processing device 1 and processing method according to the first embodiment hold the object 200 in the air, generate an elastic wave 220 inside the second wafer 202 of the object 200, irradiate the laser beam 62, which is the measurement light 61, toward the elastic wave 220, and detect the signal light 67, which is the light reflected by the elastic wave 220 from the laser beam 62, which is the measurement light 61.

[0091] For this reason, the processing apparatus 1 and processing method according to the first embodiment do not need to measure minute vibrations of the back surface 208 of the second wafer 202 that occur when the elastic wave 220 propagates to the back surface 208, and therefore do not require a complex optical system such as a laser interferometer.

[0092] As a result, the processing device 1 and processing method according to embodiment 1 have the advantage of being able to measure the inside of the object 200 in the air without submerging the object 200 in water, and does not require a complex optical system such as a laser interferometer.

[0093] Furthermore, in the processing device 1 and processing method according to embodiment 1, the wavelength λ of the laser beam 62, which is the measurement light 61 irradiated by the measurement light irradiation unit 60 of the detection device 50, and the frequency f of the laser beam 52 irradiated by the elastic wave generating unit 51 satisfy the above-mentioned equations 4 and 5, and the elastic wave 220 generated inside the second wafer 202 of the object 200 and the laser beam 62, which is the measurement light 61, satisfy the Bragg condition.

[0094] For this reason, the processing device 1 and processing method according to embodiment 1 can increase the intensity (amplitude) of the elastic wave 220 and the intensity of the signal light 67 compared to when the laser beams 52, 62 do not satisfy the Bragg condition, even when the object 200 is held in air.

[0095] [Embodiment 2] A processing apparatus and a processing method according to embodiment 2 will be described with reference to the drawings. Fig. 10 is a diagram schematically showing the configuration of a detection device of the processing apparatus according to embodiment 2. In Fig. 10, the same parts as those in embodiment 1 are denoted by the same reference numerals, and their description will be omitted.

[0096] As shown in FIG. 10, the processing device 1 of embodiment 2 has the same configuration as embodiment 1, except that the measurement light irradiation unit 60 of the detection device 50 does not have a photocoupler 65, and the signal light detection unit 70 of the detection device 50 has a filter 73 instead of a photocoupler 71 and a photodetector 74 instead of a differential amplification photodetector 72.

[0097] When a Doppler shift occurs and the frequencies of the measurement light 61 and the signal light 67 change, the wavelengths also change. Therefore, in the signal light detection unit 70 of the processing device 1 according to the second embodiment, the filter 73 transmits the signal light 67, which is reflected by the acoustic wave 220 reflected at the interface between the wafer 202 and the bonding layer 203 and travels back and forth in the thickness direction from the photocoupler 65, and which is reflected by the acoustic wave 220 in the direction from the front surface 205 to the back surface 208 of the second wafer 202, and blocks light other than the signal light 67, which is reflected by the acoustic wave 220 reflected at the interface between the wafer 202 and the bonding layer 203 and travels back and forth in the thickness direction from the front surface 205 to the back surface 208 of the second wafer 202. That is, The filter 73 transmits light of the same wavelength as the signal light 67 that is reflected at the interface between the wafer 202 and the bonding layer 203 and reflected by the elastic wave 220 in the direction from the front surface 205 to the back surface 208 of the second wafer 202, and blocks light of a different wavelength from the signal light 67 that is reflected at the interface between the wafer 202 and the bonding layer 203 and reflected by the elastic wave 220 in the direction from the front surface 205 to the back surface 208 of the second wafer 202.

[0098] In the signal light detection unit 70 of the processing apparatus 1 according to the second embodiment, the photodetector 74 detects the intensity of the signal light 67 that has passed through the filter 73, reflected at the interface between the wafer 202 and the bonding layer 203, and reflected by the elastic waves 220 traveling in a direction from the front surface 205 to the back surface 208 of the second wafer 202, and outputs the detected intensity of the signal light 67 to the controller 100. Thus, in the second embodiment, in the signal light detection step 1004, the wavelength of the laser beam 62, which is the measurement light 61, changes due to the Doppler effect when reflected by the reciprocating elastic waves 220. Therefore, the signal light detection unit 70 detects the signal light 67 that has a different wavelength from the measurement light 61 and that has been reflected by the elastic waves 220 traveling in a direction from the front surface 205 to the back surface 208 of the second wafer 202.

[0099] As in the first embodiment, the processing device 1 and processing method according to the second embodiment hold the object 200 in the air, generate elastic waves 220 inside the second wafer 202 of the object 200, irradiate a laser beam 62, which is the measurement light 61, toward the elastic waves 220, and detect signal light 67, which is light reflected by the elastic waves 220 from the laser beam 62, which is the measurement light 61. This has the effect of making it possible to measure the inside of the object 200 in the air without submerging the object 200 in water, and eliminating the need for a complex optical system such as a laser interferometer.

[0100] [Modification] Next, processing apparatuses and processing methods according to modified examples will be described. Fig. 11 is a cross-sectional view schematically showing an object to be processed by the processing apparatus and processing method according to modified example 1. Fig. 12 is a side view schematically showing processing steps of the processing method according to modified example 2. In Figs. 11 and 12, the same parts as those in embodiments 1 and 2 are designated by the same reference numerals and will be described accordingly.

[0101] The processing apparatus 1 and processing method according to Modification 1 are the same as those of Embodiment 1 or Embodiment 2, except that the object 200-1 (corresponding to the object to be processed) is different from those of Embodiment 1 and Embodiment 2. The object 200-1 to be processed by the processing apparatus 1 and processing method according to Modification 1 is a wafer such as a disk-shaped semiconductor wafer having a substrate made of silicon, GaAs, InP, GaN, SiC, or the like, as shown in Fig. 11 .

[0102] The object 200-1 to be processed by the processing device 1 and processing method according to the first modification has the center of a disk-shaped tape 210 having a diameter larger than that of the object 200 adhered to the surface 205, and a ring-shaped frame 211 having an inner diameter larger than the outer diameter of the object 200 adhered to the outer edge of the tape 210, and is then subjected to processing such as laser processing. The object 200-1 to be processed by the processing device 1 and processing method according to the first modification is subjected to processing such as laser processing by irradiating the back surface 208 side of the object 200 with laser beams 52, 62 and detecting the intensity of signal light 67, thereby detecting the condition of the surface 205 (for example, whether the surface 205 and the tape 210 are in close contact with each other, and whether there are any defects such as gaps between the surface 205 and the tape 210).

[0103] In the processing method according to the second modification, in processing step 1008, the target object 200 is ground (corresponding to processing) as shown in Fig. 12. In processing step 1008 of the processing method according to the second modification, the grinding device 80 shown in Fig. 12 suction-holds the back surface 208 of the first wafer 201 of the target object 200 onto the holding surface 82 of the holding table 81.

[0104] In variant example 2, in processing step 1008, as shown in FIG. 12, the grinding device 80 rotates the grinding wheel 83 around its axis using the spindle 85 and rotates the holding table 81 around its axis while supplying grinding water, and abuts the grinding wheel 84 against the back surface 208 of the second wafer 202 of the object 200 and moves it toward the holding table 81 at a predetermined feed speed, thereby grinding the entire back surface 208 of the second wafer 202 of the object 200 with the grinding wheel 84, thereby thinning the second wafer 202 of the object 200 to a predetermined thickness.

[0105] In the present invention, in the second modification, the target object 200-1 according to the first modification may be ground in the processing step 1008.

[0106] The processing device 1 and processing method according to the first and second variants, like those of the first and second embodiments, hold the object 200 in the air, generate elastic waves 220 inside the object 200, 200-1, irradiate the measurement light 61, which is a laser beam 62, toward the elastic waves 220, and detect signal light 67, which is light reflected by the elastic waves 220, with the laser beam 62, which is the measurement light 61. This has the effect of making it possible to measure the inside of the object 200, 200-1 in the air without submerging the object 200, 200-1 in water, and eliminating the need for a complex optical system such as a laser interferometer.

[0107] The present invention is not limited to the above-described embodiment, and can be implemented in various modifications without departing from the gist of the present invention. [Explanation of symbols]

[0108] 1 Processing equipment 10 Holding Unit 20 Laser beam irradiation unit (processing unit) 50 Detection Device 51 Elastic wave generating unit 52 Laser Beam 60 Measurement light irradiation unit 61 Measurement light 62 Laser beam (reference light) 67 Signal Light 70 Signal light detection unit 200, 200-1 Object (processing object) 205 Surface (other side) 208 Back side (one side) 220 Elastic Waves 1002 Elastic wave generation step (detection method, image generation method) 1003 Measurement light irradiation step (detection method, image generation method) 1004 Signal light detection step (comparison step, detection method, image generation method) 1006 Signal light processing step (image generation step, image generation method) 1008 Processing Steps

Claims

1. A detection method for detecting a state of the inside of an object or a state of another surface opposite to the one surface of the object from the one surface side, comprising: an elastic wave generating step of generating an elastic wave from the one surface side of the object toward the other surface side; a measurement light irradiation step of irradiating the elastic wave with a laser beam having a wavelength that is transparent to the object as measurement light; After the measurement light irradiation step, the detection method includes a signal light detection step of detecting signal light, which is light reflected by the elastic wave from the measurement light.

2. In the signal light detection step, 2. The detection method according to claim 1, wherein the signal light generated during a period of time that has elapsed since the elastic wave was generated in the elastic wave generating step is detected within a predetermined range.

3. 3. The detection method according to claim 1, further comprising a comparison step of comparing the frequency or wavelength of the signal light with that of a reference light, which is the measurement light that does not pass through the elastic wave.

4. In the signal light detection step, 3. The detection method according to claim 1, wherein the signal light having a wavelength different from that of the measurement light is detected.

5. 2. The detection method according to claim 1, wherein the elastic wave generating step generates the elastic wave by irradiating the one surface side of the object with a laser beam.

6. An image generation method for generating an image of the inside of an object or the other side opposite to one side of the object from one side of the object, comprising: an elastic wave generating step of generating an elastic wave from the one surface side of the object toward the other surface side; a measurement light irradiation step of irradiating the elastic wave with a laser beam having a wavelength that is transparent to the object as measurement light; a signal light detection step of detecting signal light, which is light reflected by the elastic wave from the measurement light after the measurement light irradiation step; and an image generating step of generating the image based on the intensity of the signal light.

7. A processing method for processing an object to be processed, comprising: an elastic wave generating step of generating elastic waves from one surface side of the object to be processed toward the other surface side; a measurement light irradiation step of irradiating a laser beam having a wavelength that is transparent to the object to be processed as measurement light toward a propagation region of the elastic wave; a signal light detection step of detecting signal light, which is light reflected by the elastic wave from the measurement light after the measurement light irradiation step; and a processing step of processing the object to be processed.

8. A detection device that detects the state of the inside of an object or the other surface opposite to the one surface side of the object from the one surface side of the object, an elastic wave generating unit that generates elastic waves from the one surface side of the object toward the other surface side; a measurement light irradiation unit that irradiates a laser beam having a wavelength that is transparent to the object as measurement light toward the elastic wave; a signal light detection unit that detects signal light, which is light reflected by the elastic wave as the measurement light.

9. A processing apparatus for processing a workpiece, a holding unit that holds the object to be processed; a processing unit for processing the object to be processed; a detection device for detecting the state of the inside of the object to be treated or the state of the other surface opposite to the one surface side of the object to be treated from the one surface side of the object to be treated, The detection device comprises: an elastic wave generating unit that generates elastic waves from the one surface side of the object to be treated toward the other surface side; a measurement light irradiation unit that irradiates a laser beam having a wavelength that is transparent to the object to be processed as measurement light toward the elastic wave; a signal light detection unit that detects signal light, which is light that is reflected by the elastic wave as the measurement light.

Images