TWI734817B - Measuring device - Google Patents

Abstract

[Problem] The problem of the present invention is to provide a simple and low-cost measuring device. [Solution] According to the present invention, a measuring device can be provided, which is a measuring device for measuring the thickness or height of a plate, and is composed of at least the following: a pulsed broadband light source, which emits a pulsed light against the plate Light in the penetrating wavelength region; fiber Bragg grating, which transmits the pulsed light emitted by the pulsed broadband light source and splits the pulsed light into different wavelengths and makes it retrograde according to the transmission distance; optical fiber transmission equipment, equipped In the fiber Bragg grating, the retrograde pulse light is split and transmitted to the optical fiber; the measuring terminal is provided with the end portion of the optical fiber divided into 2 and arranged on one of the end faces to generate the first return retrograde to the optical fiber The light mirror and the objective lens arranged on the other end surface and condensing the pulsed light on the plate; the light splitting device, the first return light and the pulsed light reflected on the upper surface of the plate The pulsed light that penetrates the plate and is reflected on the lower surface interferes with the second return light that travels retrograde to the optical fiber to split; the splitting interference waveform generation device is used to split the first return light and the second that are split by the light splitting device The wavelength is obtained from the time difference of 1 pulse of the return light, and the light intensity of each wavelength is detected to generate the spectral interference waveform of 1 pulse; and the calculation device, the spectral interference waveform generated by the spectral interference waveform generating device is waveform Analyze to calculate the thickness or height of the plate.

Description

Measuring device

FIELD OF THE INVENTION The present invention relates to a measuring device for measuring the thickness or height of a plate.

BACKGROUND OF THE INVENTION A wafer formed on the front surface of a plurality of devices such as IC, LSI, etc., divided by predetermined lines, is ground by a grinding device to form a predetermined thickness, and then processed by a dicing device and laser. The device is divided into individual devices and used in electrical equipment such as mobile phones and personal computers.

The technology that has been proposed is: the grinding device is equipped with a work chuck table for holding wafers, and a grinding device. The grinding device is rotatably arranged with a grinding wheel. The grinding grindstone on the backside of the wafer held on the work chuck is arranged in a ring shape, and the grinding device is equipped with a detection device that detects the thickness of the wafer in a non-contact manner by using a spectral interference waveform, thereby The wafer is ground to a desired thickness (see, for example, Patent Document 1). Prior Art Documents Patent Documents

Patent Document 1: Japanese Patent Laid-Open No. 2011-143488

SUMMARY OF THE INVENTION The problem to be solved by the invention. However, in the technique described in Patent Document 1 mentioned above, when the thickness or height is to be detected, the reflected light from the upper surface and the lower surface of the workpiece must be divided. By setting the reflected light into a collimation lens (collimation lens) of parallel light and a diffraction grating to diffract the interference of the two reflected lights, and further transmit the diffraction signal corresponding to each wavelength through the condenser lens to The linear image sensor detects the light intensity in each wavelength of the reflected light detected by the linear image sensor or the like to obtain the spectral interference waveform. From this, it can be seen that there are problems in that more devices are mounted to measure thickness and height, the structure is complicated, and the entire device becomes expensive.

The present invention is an invention made in view of the above-mentioned facts, and its main technical subject is to provide a simple and low-cost measuring device. Means to solve the problem

In order to solve the above-mentioned main technical problems, according to the present invention, a measuring device can be provided, which is a measuring device for measuring the thickness or height of a plate, and is composed of at least the following: a pulsed broadband light source, using a pulsed light method It emits light in the wavelength region that is penetrative to the plate; fiber Bragg grating, which transmits the pulsed light emitted by the pulsed broadband light source, and according to the transmission distance, splits the pulsed light into different wavelengths and makes it retrograde; optical fiber The transmission device is arranged on the fiber Bragg grating and splits the retrograde pulse light to the optical fiber; the measuring terminal is provided with the end portion of the optical fiber divided into 2 and arranged on one of the end faces to generate the retrograde pulse light. The first returning light mirror of the optical fiber, and the objective lens arranged on the other end surface and condensing the pulsed light on the plate; the optical splitting device, the pulsed light reflected on the upper surface of the plate and the penetrating lens The pulsed light reflected on the lower surface of the plate-like object interferes with the second return light that travels retrograde to the optical fiber to split; the split light interference waveform generation device is used to split the first return light and the second return light that are split by the light splitting device The wavelength is obtained from the time difference of one pulse of light, and the light intensity of each wavelength is detected to generate a spectral interference waveform of one pulse; and a calculation device to analyze the waveform of the spectral interference waveform generated by the spectral interference waveform generating device To calculate the thickness or height of the plate. Invention effect

The measuring device of the present invention is constructed as described above, and in particular, is constructed as follows: a pulsed broadband light source, which emits light in a wavelength region that is penetrating to a plate in a pulsed light method; and a fiber Bragg grating, which transmits The pulsed light emitted by the pulse broadband light source splits the pulsed light into different wavelengths and makes it retrograde according to the transmission distance; the optical fiber transmission equipment is installed in the fiber Bragg grating and transmits the retrograde pulsed light by branching To the optical fiber; the measurement terminal is equipped with a mirror that divides the end of the optical fiber into 2 and arranges it on one of the end faces and generates the first return light retrograde to the optical fiber, and is arranged on the other end face and pulses light The objective lens that focuses the light on the plate; the light branching device interferes with the pulsed light reflected on the upper surface of the plate and the pulsed light reflected on the lower surface of the plate, and travels retrograde to the optical fiber. The second return light is branched; the spectroscopic interference waveform generation device finds the wavelength from the time difference of one pulse of the first return light and the second return light branched by the optical branching device, and detects the light intensity of each wavelength, To generate a spectral interference waveform of 1 pulse; and a calculation device, which analyzes the spectral interference waveform generated by the spectral interference waveform generation device to calculate the thickness or height of the plate, so that the thickness can be measured with a simple configuration Deviation, and can provide low-cost measuring devices.

Modes for Carrying Out the Invention Hereinafter, the measuring device of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 shows an overall perspective view of a grinding device 1 equipped with a measuring device of the present invention, and a wafer 10 as a plate whose thickness and height are measured by the measuring device of the present invention. The grinding device 1 as shown in the figure is provided with a device casing denoted by the reference numeral 2 as a whole. The device casing 2 has a main portion 21 having a substantially rectangular parallelepiped shape, and a vertical wall 22 provided at the rear end portion (the upper right end in FIG. 1) of the main portion 21 and extending upward. On the front surface of the upright wall 22, a grinding unit 3 as a grinding device is installed so as to be movable in the up and down direction.

The grinding unit 3 includes a moving base 31 and a spindle unit 4 installed on the moving base 31. The movable base 31 is configured to be slidably engaged with a pair of guide rails arranged on the upright wall 22. On the front surface of the moving base 31 slidably mounted on the guide rail of one of the upright walls 22 in this way, the spindle unit 4 as a grinding device can be mounted through a support portion protruding forward.

The spindle unit 4 includes a spindle housing 41, a rotating spindle 42 rotatably arranged on the spindle housing 41, and a servo motor 43 as a driving source for driving and rotating the rotating spindle 42. The rotating spindle 42 rotatably supported on the spindle housing 41 is arranged with one end (lower end in FIG. 1) protruding from the lower end of the spindle housing 41, and a wheel is provided on the lower end. Mounting seat 44. In addition, a grinding wheel 5 is mounted on the lower surface of this wheel mounting seat 44. Here, the lower surface of the grinding wheel 5 is provided with a grinding grindstone 51 composed of a plurality of grinding wheel segments.

The illustrated grinding device 1 includes a grinding unit feed mechanism 6 that moves the grinding unit 3 in the vertical direction (a direction perpendicular to the holding surface of the work clamp table described later) along the pair of guide rails. . This grinding unit feed mechanism 6 is provided with a male screw 61 arranged on the front side of the upright wall 22 and extending substantially vertically, and a pulse motor 62 as a driving source for rotationally driving the male screw 61, and is equipped with The bearing member of the male screw 61 which is not shown in the figure on the back of the movable base 31 is constituted by the bearing member and the like. When the pulse motor 62 rotates forward, the moving base 31 (that is, the grinding unit 3) will fall (even if it moves forward), and when the pulse motor 62 is reversed, the moving base 31 (that is, the grinding unit 3) will rise. (Also even if it retreats).

The main part 21 of the housing 2 is provided with a work chuck mechanism 7 as a holding device for holding a plate-like object (wafer 10) as a workpiece. The work chuck mechanism 7 includes a work chuck 71, a cover member 72 covering the periphery of the work chuck 71, and telescopic devices 73 and 74 arranged in front of and behind the cover member 72. The work chuck 71 is configured to suck and hold the wafer 10 on its upper surface (holding surface) by operating a suction device not shown in the figure. In addition, the work chuck table 71 is rotatably constructed by a rotating drive device not shown in the figure, and can be placed on the workpiece shown in FIG. 1 by the work chuck table moving device not shown in the figure. It moves between the zone 70a and the grinding zone 70b facing the grinding wheel 5 (in the X-axis direction indicated by the arrow X).

Furthermore, the above-mentioned servo motor 43, pulse motor 62, and work clamp table moving equipment not shown in the figure, etc. are controlled by the control equipment 20 described later. In addition, in the embodiment shown in the figure, the wafer 10 is formed with a notch (notch) indicating the crystal orientation on the outer periphery, and a protective tape 12 as a protective member is attached to the front surface of the wafer 10, and the protective tape 12 side is held On the upper surface (holding surface) of the work chuck table 71.

The grinding device 1 shown in the figure is provided with a measuring device 8 for measuring the thickness and height of the wafer 10 held by the work chuck 71. This measuring device 8 is equipped with a measuring housing 80, and as shown in the figure, is arranged on the upper surface of the main part 21 of the rectangular parallelepiped shape of the device housing 2 so that the work clamp 71 is placed in the area where the workpiece is placed. The side of the path between 70a and the grinding area 70b, and when the work chuck 71 is moved between the workpiece placement area 70a and the grinding area 70b, it can be measured from above and held on the work chuck 71 on the wafer 10 configuration. On the lower surface of the measuring housing 80, the measuring terminal 81 is set to view the work clamp table 71 positioned directly below, and it can reciprocate in the direction indicated by the arrow Y in the figure (the Y-axis direction) Mode composition. The measuring device 8 will be described in more detail with reference to FIG. 2.

The measurement device 8 in the illustrated embodiment is provided with a broadband light source (hereinafter referred to as "pulse broadband light source 82"), and the oscillation generation includes a predetermined wavelength (for example, wavelength 1100nm~1900nm) pulse light; fiber transmission device 83a, for the pulse light LB1 from the pulse broadband light source 82 to enter; fiber bragg grating (fiber bragg grating) 83, pulse light LB1 through the fiber transmission device 83a and enter; fiber f2 , The retrograde light reflected by the fiber Bragg grating 83 is branched and transmitted by the optical fiber transmission device 83a; the optical fiber f3 is connected to the optical fiber f2; the measuring terminal 81 is provided with the end portion of the optical fiber f3 divided into two optical paths. The mirror 81c is arranged on the end face of the optical fiber f4 forming one of the optical paths and generates the first return light retrograde to the optical fiber f4, and is arranged on the end face of the other optical path (fiber f3) whose branch is 2 and transmits The light to the optical fiber f3 is condensed on the objective lens 81a of the wafer 10; the light splitting device 84 responds to the reflected light reflected on the upper surface of the wafer 10 with the light LB2 irradiated from the objective lens 81a It interferes with the reflected light that penetrates the wafer 10 and is reflected on the lower surface of the wafer 10, and is retrograde to the second return light of the optical fiber f3 and the first return light to branch; the light receiving element 85 detects The light intensity of the first return light branched by the light branching device 84 and the return light that interferes with the second return light and travels on the optical fiber f5; and the control device 20 specifies the light receiving element 85 from the time difference of 1 pulse The wavelength of the returned light of the received light is thereby detected for the light intensity of each wavelength, and the light intensity of each wavelength detected by the light receiving element 85 is input and stored. In addition, the control device 20 is provided with a spectroscopic interference waveform generation device and a calculation device. The spectroscopic interference waveform generation device generates a spectroscopic interference waveform of one pulse based on the wavelength specified by the time difference and the detected light intensity. The calculation device performs waveform analysis on the spectroscopic interference waveform generated by the spectroscopic interference waveform generation device to calculate the thickness of the wafer 10 and the heights of the front and back surfaces of the wafer 10. Furthermore, the pulse broadband light source 82 can be selected from LED, LD, SLD (Super Luminescent Diode), ASE (Amplified Spontaneous Emission), SC (Super Continuum), halogen A light source and the like are irradiated with, for example, a repetition frequency of 10 kHz (pulse interval = 100 μs) and a pulse width of 10 ns.

The fiber Bragg grating 83 is formed with diffraction gratings k1 to k17. When the diffraction gratings k1 to k17 are incident on the optical fiber f1 constituting the fiber Bragg grating 83, light having a wide-band spectrum will only reflect a specific aspect of the incident light. The wavelength component of the wavelength, and all other wavelengths are penetrated. In this embodiment, the length of the optical fiber f1 is approximately 8 km, and the diffraction gratings k1 to k17 are sequentially arranged every 500 m from the incident position. As shown in the figure, the diffraction grating k1 closest to the incident position only reflects light with a wavelength of 1100 nm, while light with other wavelength components will pass through. In addition, the next diffraction grating k2 only reflects light with a wavelength component of 1150 nm and transmits light with other wavelength components. In this way, the remaining diffraction gratings k3 to k17 will sequentially reflect light with wavelength components of 1200 nm, 1250 nm, ... 1900 nm set at every 50 nm.

In addition, the fiber transmission device 83a that functions to split the light reflected on the fiber Bragg grating 83, and the optical splitting device 84 that splits the return light reflected on the wafer 10 can be implemented by, for example, a polarization maintaining fiber coupler or a polarization maintaining fiber circulator. Choose any one of, single-mode fiber coupler, etc. appropriately. In addition, as the light receiving element 85 that detects light intensity, a generally well-known photodetector, line image sensor, or the like can be used.

The control device 20 is composed of a computer, and is equipped with a central processing unit (CPU) that performs arithmetic processing in accordance with a control program, a read-only memory (ROM) that saves the control program, etc., and is used to temporarily save the detected detection value, Read and write random access memory (RAM), input interface, and output interface for calculation results, etc. (illustrations for details are omitted). The control device 20 of this embodiment is to control each drive part of the grinding device 1, and has the following functions: generating a spectroscopic interference waveform generating device that generates a spectroscopic interference waveform as described above, and generating the spectroscopic interference waveform generating device The program of the calculation device for calculating the thickness and height of the wafer 10 is stored in a read-only memory (ROM), and the pulsed broadband light source 82 is driven, and the detection value of the light receiving element 85 is stored in random access. A memory (RAM) is used to calculate the thickness and height of the wafer 10. The grinding device 1 and the measuring device 8 of the present embodiment are configured substantially as described above, and their functions will be described below with reference to FIGS. 2 and 3.

The measurement of the thickness and height of the wafer 10 by the measuring device 8 of the present invention is performed by, for example, grinding the wafer 10 that has been placed on the work chuck 71 with the grinding device 1, and then making it from the grinding The area 70b moves in the direction of the workpiece placement area 70a, and is performed while passing directly below the measurement terminal 81. As mentioned above, the pulse broadband light source 82 is used to irradiate a pulse with a pulse width of 10ns containing a predetermined wavelength (1100nm~1900nm) component that is transparent to the wafer 10 at a repetitive frequency of 10kHz (irradiation interval=100μs). Light. The pulse light LB1 irradiated from the pulse broadband light source 82 passes through the optical fiber transmission device 83 arranged on the fiber Bragg grating 83 and enters the optical fiber f1.

The pulsed light that has entered the fiber f1 is light with a wavelength component of 1100~1900nm, and in the diffraction grating k1 closest to the incident position of the fiber f1, only the light with a wavelength component of 1100nm will be shown by the arrow in the figure The ground reflects and goes retrograde to the optical fiber f1, and the light of other wavelength components will penetrate. The light reflected by the diffraction grating k1 and retrograde to the optical fiber f1 diverges to the optical fiber f2 in the optical fiber transmission device 83a. The light branched to the optical fiber f2 is transmitted to the optical fiber f3 via the optical branching device 84, and travels at the front end of the optical fiber f3 in the optical fiber f4 that forms one of the two optical paths. The light that has traveled on the optical fiber f4 is reflected by the mirror 81c formed on the end surface of the optical fiber f4, and travels backward on the optical fiber f4 to form the first returning light. Also, at the same time, the light traveling in the other optical path (fiber f3) that has branched into two at the front end of the optical fiber f3 passes through the objective lens 81a of the measuring terminal 81 and irradiates the crystal positioned directly below. The measurement position of circle 10. The light of 1100 nm wavelength irradiated on the predetermined measurement position of the wafer 10 is reflected on the upper surface and the lower surface of the wafer 10, and the two reflected lights interfere with each other and form a second returning light retrograde to the optical fiber f3. The first returning light and the second returning light interfere with each other to become one returning light and travel retrograde to the optical fiber f3. The light branching device 84 branches to the optical fiber f5 to reach the light receiving element 85. As a result, it is possible to detect the light intensity of the returned light at the wavelength of 1100 nm in the time t1 when one pulse light is incident on the optical fiber f1. This light intensity is associated with the time t1 and the position of the X coordinate in the X axis direction and the Y coordinate in the Y axis direction of the illuminated wafer 10 and stored in the random access memory (RAM) of the control device 20. In the storage area.

Continuing the description based on FIG. 2, after the pulsed light LB1 enters the optical fiber f1 through the optical fiber transmission device 83a at time t1, the pulsed light passing through the diffraction grating k1 has a time difference and reaches the next diffraction grating k2. The diffraction grating k2 only reflects light with a wavelength component of 1150 nm, and light with other wavelength components will pass through. The 1150nm light reflected by the diffraction grating k2 as indicated by the arrow and retrograde to the optical fiber f1 is the same as the above-mentioned 1100nm light. The objective lens 81a is irradiated to the measurement position of the wafer 10 positioned directly below, and irradiated to the mirror 81c. The light reflected by the mirror 81c is retrograde to the optical fiber f4 to form the first return light. The light that has reached the wafer 10 is reflected on the upper and lower surfaces of the wafer 10 positioned directly below the measurement terminal 81a , And the two reflected lights interfere with each other to form the second returning light retrograde to the optical fiber f3. The first returning light and the second returning light interfere with each other to form one returning light and travel retrograde to the optical fiber f3, and branch at the light branching device 84 to travel on the optical fiber f5 and reach the light receiving element 85. The returning light with a wavelength of 1150 nm is reflected on the next diffraction grating k2 arranged at a position traveling 500 m from the diffraction grating k1 on the optical fiber f1, so it has It reaches the light receiving element 85 with a predetermined time difference (time t2). In this way, the light intensity of the returning light with a wavelength of 1150 nm reflected on the upper surface and the lower surface of the wafer 10 can be specified by the time t2 specified by the time difference. This light intensity is related to the specific wavelength according to time t2, and the position of the X coordinate in the X axis direction and the Y coordinate in the Y axis direction of the illuminated wafer 10 and stored in the random access memory of the control device 20 (RAM) in any storage area.

Hereinafter, similarly, among the diffraction gratings k3 to k17 on the fiber f1 of the fiber Bragg grating 83, different wavelength components (1200nm, 1250nm,...1900nm) can be set for each diffraction grating with a predetermined time difference. The light is sequentially reflected and irradiated to the mirror 81c and the wafer 10, and the first return light reflected by the mirror 81c and the second return light reflected on the upper and lower surfaces of the wafer 10 interfere with each other. Light, and the light intensity is sequentially detected by the light receiving element 85. In addition, the light intensity, the wavelength specified at the time t3 to t17, and the position of the X coordinate in the X axis direction and the Y coordinate in the Y axis direction of the irradiated wafer 10 are associated and stored in the control device 20. Random access memory (RAM) in any storage area. Furthermore, the difference in the reflection time of the light of each wavelength component generated by the fiber Bragg grating 83 is very short compared to the pulse interval. Before one pulse light is irradiated and the next pulse light is irradiated, all the wavelength components are The detection of the light intensity of the return light (1100~1900nm) ends.

As mentioned above, on the control device 20, the wavelength specified by the time difference after the pulse broadband light source 82 starts to irradiate one pulse light, the light intensity detected by the light receiving element 85, and the measured coordinate position can be associated and stored. And according to the predetermined coordinate position of each wafer 10, the spectral interference waveform as shown in FIG. 3(a) is generated. FIG. 3(a) shows that the horizontal axis is the wavelength (λ) of the returning light, and the vertical axis is the light intensity for each wavelength detected by the light receiving element 85. Hereinafter, an example in which the thickness of the wafer 10 is calculated based on the waveform analysis performed by the control device 20 based on the above-mentioned spectral interference waveform will be described.

The optical path length from the upper end of the optical fiber f3 positioned at the measurement terminal 81 to the mirror 81c is set to (L1), and the distance from the upper end of the optical fiber f3 to the upper surface of the wafer 10 held on the work chuck 71 The optical path length is set to (L2), the optical path length from the upper end of the optical fiber f3 to the lower surface of the wafer 10 held on the work clamp table 71 is set to (L3), and the optical path length (L1) and the optical path length The difference of (L2) is set to the first optical path length difference (d1=L1-L2), and the difference between the optical path length (L1) and the optical path length (L3) is set to the second optical path length difference (d2=L1-L3) , Set the difference between the optical path length (L3) and the optical path length (L2) as the third optical path length difference (d3=L3-L2). In addition, the optical path length (L1) itself is a length that does not change, and the length is set assuming the distance from the upper end of the optical fiber f3 to the upper surface of the work clamp table 71.

Next, the control device 20 performs waveform analysis based on the spectral interference waveform generated for each predetermined position of the wafer 10 as shown in FIG. 3(a) described above. Although this waveform analysis can be performed based on, for example, the Fourier transform theory and the wavelet transform theory, in the embodiments described below, it is aimed at using the Fourier transform shown in the following mathematical formula 1, mathematical formula 2, and mathematical formula 3. Examples of formulas to illustrate.

[Math 1]

[Math 2]

[Math 3]

In the above formula, λ is the wavelength, and d is the first optical path length difference (d1=L1-L2), the second optical path length difference (d2=L1-L3), and the third optical path length difference (d3=L3-L2) ), W(λn) is the window function. The above mathematical formula 1 is to obtain the optical path length difference (d) where the wave period is closest (high correlation) in the comparison between the theoretical waveform of cos and the above-mentioned spectral interference waveform (I(λn)), that is, the spectral The optical path length difference (d) for the higher correlation coefficient between the interference waveform and the theoretical waveform function. In addition, the above formula 2 is to obtain the first optical path length difference (d1=L1- L2), the second optical path length difference (d2=L1-L3), and the third optical path length difference (d3=L3-L2). 1 optical path length difference (d1=L1-L2), second optical path length difference (d2=L1-L3), and third optical path length difference (d3=L3-L2). In addition, the above-mentioned formula 3 is the average value of the result of formula 1 and the result of formula 2 obtained.

The control device 20 is capable of performing operations based on the above-mentioned Mathematical Formula 1, Mathematical Formula 2, and Mathematical Formula 3, and can obtain FIG. 3 (b ) Shows the waveform of the signal strength. In Figure 3(b), the horizontal axis is the display optical path length difference (d), and the vertical axis is the display signal intensity. In the example shown in FIG. 3(b), the signal intensity is displayed at a position (s1) where the optical path length difference (d) is 500 μm, a position (s2) at 330 μm, and a position (s3) at 180 μm. That is, the signal intensity s1 at the position where the optical path length difference (d) is 500 μm is the position of the first optical path length difference (d1=L1-L2), and it represents the wafer positioned above on the work chuck 71 The height of the back surface 10b of 11 from the upper surface of the work clamp table 71. In addition, the signal intensity s2 at the position where the optical path length difference (d) is 300 μm is the position of the second optical path length difference (d2=L1-L3), and represents the wafer 11 positioned below on the work chuck 71 The height of the front surface 10a from the upper surface of the work clamp table 71. In addition, the signal intensity s3 at the position where the optical path length difference (d) is 150 μm is the position of the third optical path length difference (d3=L3-L2), and represents the thickness of the wafer 10. In addition, the coordinates (X coordinate, Y coordinate) of the measurement position specified by the position in the X-axis direction relative to the measurement terminal 87 and the work clamp table 71 and the position of the objective lens 88 positioned in the Y-axis direction The height and thickness of the wafer 10 are stored in the random access memory (RAM) of the control device 20.

In this embodiment, the drive mechanism 81b holding the measuring terminal 81 is configured to be reciprocating in the direction indicated by the arrow Y1, and the measuring terminal 81 is positioned relative to the The wafer 10 directly below the measuring device 8 moves in the Y-axis direction, and the work chuck 71 is moved in the X-axis direction, while performing the above-mentioned thickness measurement on the entire surface of the wafer 10.

According to the measuring device 8 in the illustrated embodiment, the thickness of the wafer 10 can be easily obtained with a simple configuration, and it is detected based on the spectroscopic interference waveform obtained by the difference in the optical path length of the reflected light caused by the reflection. The thickness and height of the wafer 10 during the processing of the wafer 10, therefore, the thickness and height of the wafer 11 can be accurately measured without being affected by changes in the thickness of the protective tape 12 attached to the front surface of the wafer 10 high.

The measuring device 8 is configured as described above. Hereinafter, the procedure for grinding the wafer 10 to a predetermined thickness using the grinding device 1 provided with the measuring device 8 will be described.

The wafer 10 with the protective tape 12 attached to the front side is placed on the work chuck table 71 of the workpiece placement area 70a in the grinding apparatus 1 shown in FIG. 1 by placing the protective tape 12 side The suction device, which is not shown in the action diagram, is sucked and held on the work clamp table 71. Therefore, the wafer 10 held on the work chuck table 71 becomes the back surface 10b on the upper side.

Next, the control device 20 will actuate a moving device not shown in the work chuck table 71 holding the wafer 10, move the work chuck table 71 to be positioned to the grinding area 70b, and grind a plurality of grinding wheels 5 The outer peripheral edge of the grinding stone 51 is positioned to pass through the rotation center of the work chuck 71.

In this way, the grinding wheel 5 and the wafer 10 held on the work chuck table 71 are set to a predetermined positional relationship, and the control device 20 drives a rotation driving device not shown in the figure to rotate at a rotation speed of, for example, 300 rpm The work clamp table 71 is rotated, and the aforementioned servo motor 43 is driven to rotate the grinding wheel 5 at a rotation speed of, for example, 6000 rpm. Then, grinding water is supplied to the wafer 10, and the pulse motor 62 of the grinding unit feed mechanism 6 is driven forward to lower the grinding wheel 5 (grinding feed), and the plural grinding stones 51 The predetermined pressure is pressed against the surface to be ground, which is the upper surface (back surface 10b) of the wafer 10. As a result, the ground surface of the wafer 10 can be ground (grinding step).

After the grinding step is completed, the work chuck 71 holding the ground wafer 10 can be moved toward the workpiece placement area 70a located forward in the X-axis direction, and the wafer 10 can be positioned at The measuring device 8 is directly below the measuring terminal 81, and the measuring device 8 is actuated as described above to obtain the spectral interference waveform corresponding to each coordinate position on the wafer 10 and the waveform analysis equipment is executed to measure and store the wafer 10 The thickness and height. By performing such a measurement for each predetermined position of the wafer 10, and storing the thickness and height of the surface of the wafer 10, and confirming the thickness and height of the entire surface of the wafer 10 after grinding, the grinding can be determined The step is good, and re-grinding is implemented as needed, and the grinding step is implemented until it reaches a predetermined thickness.

In addition, in the above-mentioned embodiment, although the measurement by the measuring device 8 is performed on the entire surface of the wafer for which the grinding step has been completed is described, it is not limited to this. For example, the The installation position of the measuring housing 80 of the measuring device 8 is set in the vicinity of the grinding area 70b shown in FIG. 1. With such a configuration, it is also possible to make the wafer 10 held on the work chuck mechanism 7 of the grinding device 1 receive the action of the grinding wheel 5 and be ground, and it can be compared with the exposed wafer 10 When facing, move the measuring terminal 85 so that it is submerged in the grinding water supplied during grinding and positioned to measure the thickness of the wafer 10 being ground, and it can be achieved by The thickness of 10 is fed back to the control device 20 to efficiently grind to the desired thickness and height.

In addition, the measuring device 8 constructed according to the present invention does not need to be arranged in the grinding device 1 as in this embodiment, and may be constructed as a single device independent of the grinding device 1. In addition, it can also be combined with another processing device different from the grinding device 1. For example, it can also be applied to irradiate a laser beam on a predetermined dividing line of a wafer formed on the front surface divided by the predetermined dividing line of a plurality of devices. On a laser processing device that performs the processing that becomes the starting point of the division and divides it into individual devices. More specifically, a laser processing method in which the condensing point of the laser light having a wavelength penetrating the wafer is positioned inside the planned dividing line and irradiated, and a modified layer is formed inside along the planned dividing line It is known that with the measuring device of the present invention, it is also possible to measure the surface height of the wafer along the predetermined dividing line, and to control the position of the condensing point of the laser light according to the measured height of the wafer surface. By doing this, the position of the condensing point during laser processing can be positioned at a desired depth inside the wafer, and the division can be performed well.

Furthermore, according to the measuring device of the present invention, although the required thickness and height of the plate to be measured can be obtained, it is also possible to measure only any one of the thickness and height as required.

1‧‧‧Grinding device 10‧‧‧wafer 10a‧‧‧front 10b‧‧‧back 12‧‧‧protective tape 2‧‧‧device housing 20‧‧‧control equipment 21‧‧‧main part 22‧ ‧‧Vertical wall 3‧‧‧Grinding unit 31‧‧‧Mobile base 4‧‧‧Spindle unit 41‧‧‧Spindle housing 42‧‧‧Rotating spindle 43‧‧‧Servo motor 44‧‧‧Wheel mount 5‧‧‧Grinding wheel 51‧‧‧Grinding grinding stone Processing object placement area 70b‧‧‧Grinding area 71‧‧‧Working clamp table 72‧‧‧Cover member 73,74‧‧‧Telescopic device 8‧‧‧Thickness measuring device 80‧‧‧Measuring housing 81‧‧ ‧Measurement terminal 81a‧‧‧Object lens 81b‧‧‧Drive mechanism 81c‧‧‧Mirror 82‧‧‧Pulse broadband light source 83‧‧‧Fiber Bragg grating 83a‧‧‧Optical fiber transmission equipment 84‧‧‧Optical splitting equipment 85 ‧‧‧Light receiving element LB1‧‧‧Pulse light LB2‧‧‧Light f1~f5‧‧‧Optical fiber k1~k17‧‧‧Diffraction grating s1, s2, s3‧‧‧Signal intensity Y1‧‧‧Arrow X, Y ‧‧‧direction

Fig. 1 is a perspective view of a grinding device to which the measuring device constructed according to the present invention can be applied. Fig. 2 is an explanatory diagram for explaining the structure of a measuring device constructed according to the present invention. Figures 3(a) and (b) show an example of the spectral interference waveform generated by the measuring device shown in Figure 2, and the difference in optical path length and signal intensity obtained by waveform analysis of the spectral interference waveform. Diagram of an example.

10‧‧‧wafer

20‧‧‧Control equipment

71‧‧‧Working Clamping Table

80‧‧‧Measuring shell

81‧‧‧Determination terminal

81a‧‧‧Objective lens

81b‧‧‧Drive mechanism

81c‧‧‧Mirror

82‧‧‧Pulse broadband light source

83‧‧‧Fiber Bragg Grating

83a‧‧‧Fiber optic transmission equipment

84‧‧‧Optical branch equipment

85‧‧‧Light receiving element

LB1‧‧‧Pulse light

LB2‧‧‧Light

f1~f5‧‧‧Fiber

k1, k2, k3, k4, k5, k6, k7, k17‧‧‧ diffraction grating

Claims (1)

A measuring device is a measuring device for measuring the thickness or height of a plate, and is composed of at least the following: a pulsed broadband light source, which emits light in a wavelength region that is penetrating to the plate by means of pulsed light; an optical fiber; Bragg grating, which transmits the pulsed light emitted by the pulsed broadband light source, and according to the transmission distance, splits the pulsed light into different wavelengths and makes it retrograde; optical fiber transmission equipment is installed in the fiber Bragg grating and will have The retrograde pulsed light splits and is transmitted to the optical fiber; the measuring terminal is equipped with a mirror that divides the end of the optical fiber into 2 and arranges it on one of the end faces and generates the first return light retrograde to the optical fiber, and is arranged in The other end surface condenses the pulsed light on the object lens of the plate; the light splitting device is used for the first return light and the pulsed light reflected on the upper surface of the plate and penetrate the plate. The pulsed light reflected on the lower surface interferes with the second return light traveling retrograde to the optical fiber to split; the split light interference waveform generating device is composed of one pulse of the first return light and the second return light split by the optical splitting device The time difference of the pulsed light of each wavelength included in the light finds the wavelength, and detects the light intensity of each wavelength to generate a spectral interference waveform; and a calculation device to analyze the waveform of the spectral interference waveform generated by the spectral interference waveform generating device To calculate the thickness or height of the plate.

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