Interference signal measuring device

Abstract

This invention provides an interference signal measuring device that can perform measurement of the machining quality of a workpiece's processed portion using a white light interferometer in a short amount of time. [Solution] The apparatus comprises a machining head (blades 22A, 22B) for machining a workpiece (W), a relative movement mechanism (49) for moving the machining head relative to a table, a white light interferometer (24) that emits white light toward the workpiece and detects interference signals between the white light reflected by the workpiece and the white light reflected by a reference plane, a scanning control unit (85) that drives the relative movement mechanism to scan the machining head and the white light interferometer together in a direction perpendicular to the table, thereby changing the optical path length of the white light reflected by the workpiece, an interference signal acquisition unit (81) that intermittently acquires interference signals from the white light interferometer during scanning, and an estimation unit (82) that estimates the position of the white light interferometer based on the interference signals acquired by the interference signal acquisition unit.

Description

Technical Field

[0001] The present invention relates to a workpiece processing apparatus for processing a workpiece and a control method for the workpiece processing apparatus.

Background Art

[0002] There is known a dicing apparatus (workpiece processing apparatus) that cuts a workpiece such as a wafer with a disk-shaped blade that is rotated at high speed by a spindle. Further, as a dicing apparatus, a twin spindle dicer having two spindles to which blades are attached is known. And, as a method of cutting or severing a workpiece by this twin spindle dicer, a meeting cutting method and a step cut method are known.

[0003] The meeting cutting method is a method of cutting two streets at once with two blades. Further, the step cut method is a method of cutting a wafer along a street by cutting a groove having a predetermined depth along the street with a first blade and then cutting the bottom of the groove with a second blade.

[0004] Since the blade of such a dicing apparatus wears due to use, chipping may occur on the cutting surface of the workpiece by the blade. Further, due to the influence of thermal deformation of the blade, the position of a groove (kerf) formed in the workpiece by the blade may deviate from the center of the street. For this reason, in the dicing apparatus, a kerf check of the blade is performed at a preset timing.

[0005] For example, in the dicing apparatuses described in Patent Document 1 and Patent Document 2, a groove formed in a workpiece by a blade is photographed with a camera (a microscope for alignment or the like), and the kerf position, kerf width, and presence or absence of chipping of the groove are measured based on the photographed image of this camera.

[0006] Furthermore, the laser processing machines described in Patent Documents 3 and 4 are equipped with a white light interferometer that emits white light toward the workpiece and detects the interference signal between the white light reflected from the workpiece and the white light reflected from the reference plane. This laser processing machine vertically scans the white light interferometer in the Z-axis direction and acquires interference signals output from each pixel of the white light interferometer (a pixel of the image sensor that captures the interference signal) at each position in the Z-axis direction. Based on the detection results, which detect the Z-axis position of the white light interferometer where the intensity of the interference signal peaks for each pixel, this laser processing machine generates a three-dimensional image of the workpiece to verify the processing state of the workpiece. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] Japanese Patent Publication No. 2011-165826 [Patent Document 2] Japanese Patent Publication No. 2001-129822 [Patent Document 3] Japanese Patent Publication No. 2015-099026 [Patent Document 4] Japanese Patent Publication No. 2015-38438 [Overview of the project] [Problems that the invention aims to solve]

[0008] Incidentally, in the dicing apparatuses described in Patent Documents 1 and 2 above, the grooves are photographed using a microscope. However, since the images of the grooves are two-dimensional images of the grooves viewed from the top surface of the workpiece, it is not possible to detect the groove depth and cross-sectional shape based on the images of the grooves. Furthermore, when the step-cut cutting method described above is performed with this dicing apparatus, the grooves formed by the second blade overlap with the grooves formed by the first blade. For this reason, it is difficult to confirm the machining quality (kerf position and kerf width, etc.) of the grooves formed by the second blade based on the microscope images.

[0009] Therefore, a step kerf check is known in which an uncut portion of the workpiece is cut with a first blade, and another uncut portion of the workpiece is cut with a second blade, and the kerf check of each blade is performed based on images taken with a camera of the two grooves formed by each blade. (See Patent Document 2 above.) In this case, the machining quality of the groove formed by the second blade can be confirmed based on the images taken with a microscope.

[0010] However, this method requires the second blade to cut the uncut areas of the workpiece, but since the second blade is thinner than the first blade, cutting the uncut areas with the second blade places a greater load on it. Also, because the processing conditions of the workpiece by the second blade differ between step cutting and kerf checking, for example, the second blade may twist during kerf checking, potentially forming a groove in a different position than during step cutting. In other words, there is a possibility that grooves will not be formed in the same position during step cutting and kerf checking, and as a result, it may not be possible to accurately measure the processing quality of the grooves during step cutting.

[0011] On the other hand, in the laser processing machines described in Patent Documents 3 and 4, the white light interferometer is scanned vertically in the Z-axis direction, and the groove depth and cross-sectional shape are measured based on the interference signals output from the white light interferometer at each position in the Z-axis direction. Therefore, the problems described in Patent Documents 1 and 2 do not occur.

[0012] However, when detecting the Z-axis position of the white light interferometer where the intensity of the interference signal peaks (hereinafter referred to as the peak position) for each pixel of the white light interferometer by vertical scanning, as described in Patent Documents 3 and 4, it is necessary to acquire the interference signal from the white light interferometer at a high sampling rate (fine pitch) that can reliably detect the peak position for each pixel. Furthermore, when measuring the cross-sectional shape of a groove using a white light interferometer, it is necessary to increase the vertical scanning movement range (amount of movement) compared to when measuring the surface roughness of various objects in general. For this reason, detecting the interference signal at the high sampling rate described above results in the problem that measuring the cross-sectional shape of the groove takes an extremely long time.

[0013] This invention has been made in view of these circumstances, and aims to provide a workpiece processing apparatus and a control method for the workpiece processing apparatus that can perform measurement of the processing quality of the processed part of a workpiece using a white light interferometer in a short amount of time. [Means for solving the problem]

[0014] A workpiece processing apparatus for achieving the object of the present invention comprises: a table for holding a flat workpiece; a processing head for processing the workpiece held on the table; a relative movement mechanism for moving the processing head relative to the table; a white light interferometer provided integrally with the processing head, which emits white light toward a workpiece formed on the workpiece and detects interference signals between the white light reflected by the workpiece and the white light reflected by a reference plane for each pixel; a scanning control unit that drives the relative movement mechanism to perform a step scan of the processing head and the white light interferometer in a direction perpendicular to the table; an interference signal acquisition unit that acquires an interference signal for each pixel from the white light interferometer at each step of the step scan; and an estimation unit that estimates the position of the white light interferometer where the intensity of the interference signal peaks, based on the interference signals for each pixel acquired by the interference signal acquisition unit at each step.

[0015] With this workpiece processing device, the position of the white interferometer where the intensity of the interference signal peaks can be estimated for each pixel based on the interference signal acquired from the white interferometer for each pixel at each step of the step scan. Therefore, it is not necessary to vertically scan the white interferometer at a high sampling rate (fine pitch).

[0016] In another aspect of the present invention, the workpiece processing apparatus has a scanning control unit that has a function to adjust the step width of the step scan. This allows the step width (number of steps) to be adjusted according to the type of workpiece, etc.

[0017] In another aspect of the present invention, the scanning range of the step scan is divided into multiple scanning ranges according to the part of the workpiece, and the scanning control unit adjusts the step width of the step scan for each scanning range based on the step width determined for each scanning range. As a result, the step scan of the white light interferometer can be performed at a high sampling rate in parts that are important for measuring the processing quality of the workpiece, and at a low sampling rate in parts that do not significantly affect the measurement of processing quality. As a result, the processing quality of the workpiece can be measured quickly and accurately.

[0018] In another embodiment of the present invention, a workpiece processing apparatus is provided, which includes a processing quality measurement unit that measures the processing quality of the workpiece based on the estimation result of the estimation unit. By performing a step scan of the white light interferometer, the processing quality of the workpiece's processing portion using the white light interferometer can be measured in a short time.

[0019] In another aspect of the present invention, a workpiece processing apparatus comprises a processing control unit that drives a processing head and a relative movement mechanism to form a workpiece on the workpiece using the processing head, and a measurement control unit that operates a white light interferometer and a scanning control unit at a position where white light can be irradiated onto the workpiece, wherein a processing quality measurement unit measures at least one of the processing position and processing shape of the workpiece as processing quality. This allows for measurement of the processing quality of the workpiece formed by the processing head in a short amount of time.

[0020] In a workpiece processing apparatus according to another aspect of the present invention, the measurement control unit drives the relative movement mechanism based on a known position of the processed portion formed by the processing head, and relatively moves the white interferometer to a position where the processed portion can be irradiated with white light. As a result, the position adjustment of the white interferometer with respect to the processed portion can be quickly executed without searching for the processed portion.

[0021] In a workpiece processing apparatus according to another aspect of the present invention, a correction value determination unit that determines a correction value for correcting at least one of the processing position and the processing shape of the processed portion based on the measurement result of the processing quality measurement unit is provided, and the processing control unit drives the processing head and the relative movement mechanism based on the correction value determined by the correction value determination unit to form the processed portion on the workpiece. As a result, the processing accuracy of the processed portion can be further improved.

[0022] In a workpiece processing apparatus according to another aspect of the present invention, the processing head cuts the workpiece with a rotating disk-shaped blade.

[0023] In a workpiece processing apparatus according to another aspect of the present invention, the processing head cuts the workpiece with a rotating disk-shaped blade, the processing quality measurement unit measures the cross-sectional shape of the processed portion as the processing quality, and a blade shape measurement unit that measures the tip shape of the blade based on the measurement result of the cross-sectional shape by the processing quality measurement unit is provided. As a result, the measurement of the tip shape of the blade can be executed in a short time.

[0024] A control method for a workpiece processing apparatus for achieving the object of the present invention includes a scanning control step of relatively step-scanning a white interferometer that emits white light toward a processed portion formed on a flat workpiece held on a table and detects an interference signal between the white light reflected by the processed portion and the white light reflected by a reference surface pixel by pixel along a direction perpendicular to the table integrally with a processing head for processing the workpiece, an interference signal acquisition step of acquiring an interference signal for each pixel from the white interferometer for each step of the step-scanning, and an estimation step of estimating, for each pixel, a position of the white interferometer where the intensity of the interference signal peaks based on the interference signal for each pixel acquired for each step in the interference signal acquisition step.

[0025] In a control method for a workpiece processing apparatus according to another aspect of the present invention, there is a processing quality measurement step of measuring the processing quality of the processed portion based on the estimation result in the estimation step.

Advantages of the Invention

[0026] The present invention can execute measurement of the processing quality of a processed portion of a workpiece using a white interferometer in a short time.

Brief Description of the Drawings

[0027] [Figure 1] It is a perspective view of a dicing apparatus according to the first embodiment. [Figure 2] It is an external perspective view of the processing portion. [Figure 3] It is an enlarged front view of the white interferometer shown in FIG. 2. [Figure 4] It is a cross-sectional view of the white interferometer. [Figure 5] It is a functional block diagram of an overall control unit of the dicing apparatus according to the first embodiment. [Figure 6] It is an explanatory diagram for explaining the meeting cutting method. [Figure 7] It is an explanatory diagram for explaining the step cut method. [Figure 8] It is a cross-sectional view of a part of a workpiece cut by the step cut method. [Figure 9]This is an explanatory diagram illustrating the step scanning motion in the Z-axis direction of a white light interferometer. [Figure 10] This is an explanatory diagram illustrating the process of estimating the peak position of a white light interferometer by the estimation unit. [Figure 11] This is an explanatory diagram illustrating the measurement of the three-dimensional shape of a groove by the processing quality measurement unit. [Figure 12] This is an explanatory diagram illustrating the shape measurement of the cross-sectional shape of the groove along the Y-axis direction by the processing quality measurement unit. [Figure 13] This is an explanatory diagram illustrating an example of kerf checking of grooves formed by a step-cut method, that is, measuring the machining position of the grooves within the workpiece. [Figure 14] This flowchart shows the flow of the cutting process of a workpiece using the dicing apparatus of the first embodiment, particularly the flow of the measurement process for the machining quality (machining position) of the grooves. [Figure 15] This is an explanatory diagram illustrating the cutting process of a workpiece using a dicing apparatus of the second embodiment and the back surface grinding of a workpiece using a grinding (polishing) apparatus (not shown). [Figure 16] This is an explanatory diagram illustrating the shape measurement of the cross-sectional shape of a half-cut groove along the Y-axis direction by the processing quality measurement unit of the second embodiment. [Figure 17] This is a functional block diagram of the central control unit of the dicing apparatus according to the third embodiment. [Figure 18] This is an explanatory diagram illustrating the shape measurement of the cross-sectional shape of a half-cut groove by the processing quality measurement unit of the third embodiment. [Figure 19] This flowchart shows the flow of the blade tip shape measurement process using the dicing apparatus of the third embodiment. [Figure 20] This is an explanatory diagram illustrating the step scanning of a white light interferometer using a dicing apparatus according to the fourth embodiment. [Figure 21] This is an enlarged view of the groove in Figure 20 and is a diagram illustrating the position of the reference focal point of the measurement light for each step of the step scanning in the fourth embodiment. [Modes for carrying out the invention]

[0028] [First Embodiment] Figure 1 is a perspective view of the dicing apparatus 10 according to the first embodiment. Note that the XYZ axes in the figure are mutually orthogonal axes, with the XY axes being parallel to the horizontal direction and the Z axis being perpendicular to the horizontal direction.

[0029] The dicing apparatus 10 corresponds to the workpiece processing apparatus of the present invention and cuts a flat workpiece W such as a semiconductor wafer. This dicing apparatus 10 includes a load port 12, a transport mechanism 14, a processing section 16, and a cleaning section 18.

[0030] A cassette containing numerous workpieces W mounted on a frame F is placed on the load port 12. The transport mechanism 14 transports the workpieces W. The processing unit 16 performs dicing of the workpieces W. The cleaning unit 18 spin-cleans the diced workpieces W. Inside the housing 10A of the dicing device 10, there is a control unit 60 (see Figure 5) that controls the operation of each part of the dicing device 10. The control unit 60 may be located outside the housing 10A.

[0031] The unprocessed (uncut) workpiece W stored in the cassette placed on the load port 12 is transported to the processing section 16 by the transport mechanism 14, where it is cut or grooved to separate into individual chips. The processed workpiece W from the processing section 16 is then transported to the cleaning section 18 by the transport mechanism 14, where it is cleaned, and then transported back to the load port 12 by the transport mechanism 14 and stored in the cassette.

[0032] Figure 2 is an external perspective view of the processing unit 16. As shown in Figure 2 and Figure 1 described above, the processing unit 16 is the twin spindle dicer described above and comprises a pair of blades 21A, 21B, a blade cover (not shown), a pair of spindles 22A, 22B, a microscope 23, a white light interferometer 24, and a table 31.

[0033] Blades 21A and 21B are formed in a disc shape. The tip shape of blades 21A and 21B, that is, the cross-sectional shape of the outer circumference (cutting edge) of the blades along the radial direction of blades 21A and 21B, is rectangular (other shapes such as V-shape are also acceptable). Blades 21A and 21B are arranged opposite each other in the Y-axis direction and are held on spindles 22A and 22B so as to be rotatable around blade rotation axes parallel to the Y-axis direction.

[0034] The spindles 22A and 22B have built-in high-frequency motors that rotate the blades 21A and 21B at high speed around the blade rotation axis. As a result, the workpiece W is cut from its front side by the blades 21A and 21B. Therefore, the blade 21A and spindle 22A, and the blade 21B and spindle 22B, respectively, correspond to the machining heads of the present invention.

[0035] A groove 25A (see Figures 6 and 7), corresponding to the workpiece portion of the present invention, is formed in the workpiece W by cutting with blade 21A. In addition, a groove 25B (see Figures 6 and 7), corresponding to the workpiece portion of the present invention, is formed in the workpiece W by cutting with blade 21B.

[0036] The microscope 23 is mounted on the Z carriage 44 integrally with the spindle 22A and is held by the Y carriage 43 and Z carriage 44 so as to be movable in the YZ axis direction integrally with the spindle 22A. The microscope 23 is an imaging device having an imaging optical system and an image sensor (for example, a COMS (Complementary Metal Oxide Semiconductor) camera), although it is not shown in the figure. The microscope 23 may be composed of a high-magnification microscope and a low-magnification microscope with different imaging magnifications. The microscope 23 photographs the front surface of the workpiece W during the cutting process of the workpiece W. The image of the workpiece W taken by the microscope 23 is used for alignment between the workpiece W and the blades 21A and 21B.

[0037] Figure 3 is an enlarged front view of the white light interferometer 24 shown in Figure 2. As shown in Figure 3 and Figure 2 described above, the white light interferometer 24 is mounted on the Z carriage 44 integrally with the spindle 22B and is held so as to be movable in the YZ axis direction by the Y carriage 43 and the Z carriage 44. The white light interferometer 24 is used to measure the machining quality of grooves 25A and 25B (see Figures 6 and 7) formed in the workpiece W by the blades 21A and 21B. Furthermore, when measuring this machining quality, the white light interferometer 24 is vertically scanned in the Z axis direction perpendicular to the table 31 (workpiece W) via the Z carriage 44, more specifically, it is step-scanned.

[0038] The table 31 has a workpiece holding surface 31a formed in a porous manner, and this workpiece holding surface 31a holds the workpiece W by suction from its back side. The table 31 is held so as to be movable in the X-axis direction by the X carriage 36 described later, and is also held so as to be rotatable about the rotation axis CA by the rotation unit 37 described later.

[0039] The machining section 16 is provided with an X-base 32, an X-guide 34, an X-drive unit 35, an X-carriage 36, and a rotary unit 37. The X-base 32 has a flat plate shape extending in the X-axis direction, and the X-guide 34 is provided on its upper surface in the Z-axis direction. The X-guide 34 has a shape extending in the X-axis direction and guides the X-carriage 36 along the X-axis direction. The X-drive unit 35 uses an actuator such as a linear motor to move (drive) the X-carriage 36 in the X-axis direction along the X-guide 34.

[0040] The rotating unit 37 is provided on the upper surface of the X carriage 36. A table 31 is also provided on the upper surface of the rotating unit 37. The rotating unit 37 is rotationally driven by a rotation drive unit 38 (see Figure 5), which consists of a motor and gears. As a result, the rotating unit 37 rotates the table 31 in the θ direction about its rotation axis CA.

[0041] The workpiece W, transported from the load port 12 by the transport mechanism 14, is held by the table 31 through suction, and moves and rotates together with the table 31.

[0042] The machining section 16 is also provided with a Y-base 41, a Y-guide 42, a pair of Y-carriages 43, and a pair of Z-carriages 44. The Y-base 41 has a gate-like shape that straddles the X-base 32 in the Y-axis direction. A Y-guide 42 is provided on the X-axis side of the Y-base 41. The Y-guide 42 has a shape that extends in the Y-axis direction and guides the pair of Y-carriages 43 along the Y-axis direction. The pair of Y-carriages 43 are driven independently along the Y-guide 42 by a Y-drive unit 46 (see Figure 5), which is an actuator composed of, for example, a stepping motor and a ball screw.

[0043] Each of the pair of Y carriages 43 is provided with a Z carriage 44 that is movable in the Z-axis direction via a Z drive unit 48 (see Figure 5) which is composed of an actuator such as a stepping motor. One of the Z carriages 44 is equipped with a spindle 22A and a microscope 23, and the other Z carriage 44 is equipped with a spindle 22B and a white light interferometer 24.

[0044] By driving the X carriage 36, the rotating unit 37, each Y carriage 43, and each Z carriage 44, the blades 21A, 21B, the microscope 23, and the white light interferometer 24 can be moved relative to the table 31 and the workpiece W in the XYZ axis direction and the θ direction.

[0045] Figure 4 is a cross-sectional view of the white light interferometer 24. As shown in Figure 4, the white light interferometer 24 is a so-called Mirau-type white light interferometer and comprises a housing 50, a white light source 51, a first beam splitter 52, an objective lens 53, a glass plate 54, a second beam splitter 55, and an imaging unit 56.

[0046] The housing 50 houses the first beam splitter 52, the objective lens 53, the glass plate 54, and the second beam splitter 55. Within the housing 50, the second beam splitter 55, the glass plate 54, the objective lens 53, and the first beam splitter 52 are arranged from the lower side to the upper side in the Z-axis direction. A white light source 51 is mounted on the side of the housing 50 and on the side of the first beam splitter 52. Furthermore, an imaging unit 56 is mounted on the top surface of the housing 50 and above the first beam splitter 52.

[0047] The white light source 51 emits white light L1 (light mixed with light from various wavelength ranges of visible light) toward the first beam splitter 52 while the white light interferometer 24 is scanned in one step (or multiple steps). The first beam splitter 52 reflects a portion of the white light L1 incident from the white light source 51 toward the objective lens 53. The first beam splitter 52 also transmits a portion of the interference signal L4 incident from the objective lens 53 and emits this portion toward the imaging unit 56.

[0048] The objective lens 53 focuses the white light L1 incident from the first beam splitter 52 onto the focal point P of the workpiece W. The diameter of the focal point P (focused spot) is not particularly limited.

[0049] The glass plate 54 has a mirror 54a in its center that functions as a reference surface. The glass plate 54 (excluding the mirror 54a) transmits the white light L1 incident from the objective lens 53 directly and emits it towards the second beam splitter 55.

[0050] The second beam splitter 55 splits the white light L1 focused by the objective lens 53 into measurement light L2 and reference light L3. It transmits the measurement light L2 to the workpiece W and reflects the reference light L3 toward the mirror 54a. The measurement light L2 that irradiates the workpiece W is reflected by the workpiece W and incident on the second beam splitter 55. The reference light L3 reflected by the mirror 54a is incident on the second beam splitter 55 and a portion of it is reflected by the second beam splitter 55. This generates an interference signal L4 (interference light) between the measurement light L2 and the reference light L3. This interference signal L4 is incident on the imaging unit 56 via the glass plate 54, the objective lens 53, and the first beam splitter 52.

[0051] The optical path length of the reference light L3 is constant, but the optical path length of the measurement light L2 changes according to the vertical scanning of the white light interferometer 24. As is well known, when the difference in optical path lengths between the measurement light L2 and the reference light L3 is zero (including nearly zero), the interference between the measurement light L2 and the reference light L3 across all wavelength ranges of visible light reinforces each other, resulting in the maximum signal intensity of the interference signal L4 (see, for example, Japanese Patent Application Publication No. 2017-106860).

[0052] The imaging unit 56 is equipped with a two-dimensional image sensor of the CCD (Charge Coupled Device) or CMOS (Complementary Metal Oxide Semiconductor) type, in which multiple pixels (photodetectors) are arranged in a two-dimensional array in the XY axis direction. While the white light interferometer 24 is performing one vertical scan (or multiple scans), the imaging unit 56 captures the interference signal L4 incident from the first beam splitter 52 for each pixel, thereby detecting (acquiring) the interference signal L4 for each pixel and outputting the interference signal L4 for each pixel to the control unit 60 (see Figure 5).

[0053] [Functions of the General Control Unit] Figure 5 is a functional block diagram of the central control unit 60 of the dicing apparatus 10 according to the first embodiment. As shown in Figure 5, the central control unit 60 includes an arithmetic circuit composed of various processors and memory. The various processors include CPUs (Central Processing Units), GPUs (Graphics Processing Units), ASICs (Application Specific Integrated Circuits), and programmable logic devices [e.g., SPLDs (Simple Programmable Logic Devices), CPLDs (Complex Programmable Logic Devices), and FPGAs (Field Programmable Gate Arrays)]. The various functions of the central control unit 60 may be realized by a single processor, or by multiple processors of the same or different types.

[0054] In addition to the previously described spindles 22A, 22B, microscope 23, white light interferometer 24, X drive unit 35, rotation drive unit 38, Y drive unit 46, and Z drive unit 48, the control unit 60 is connected to an operation unit 62, a memory unit 64, a display unit 66, and the like.

[0055] The operation unit 62 uses a keyboard, mouse, control panel, and operation buttons to receive input from the operator for various operations. The storage unit 64 stores the control program for the dicing device 10 (not shown) and also stores measurement results from the processing quality measurement unit 83, which will be described later. The display unit 66 uses various known monitors, such as a liquid crystal display. This display unit 66 displays the measurement results from the processing quality measurement unit 83 and various setting screens for the dicing device 10.

[0056] The integrated control unit 60 functions as the blade drive control unit 70, movement control unit 72, imaging control unit 74, detection control unit 76, processing control unit 78, measurement control unit 80, interference signal acquisition unit 81, estimation unit 82, processing quality measurement unit 83, and correction value determination unit 84 by executing a control program (not shown) stored in the memory unit 64. Note that the "~unit" in the description of the integrated control unit 60 may also be described as a "~circuit," "~device," or "~equipment." In other words, the "~unit" may consist of firmware, software, hardware, or a combination thereof.

[0057] The blade drive control unit 70 controls the rotational drive of the blades 21A and 21B by the spindles 22A and 22B.

[0058] The movement control unit 72 drives a relative movement mechanism 49, which includes an X drive unit 35 (X carriage 36), a rotation drive unit 38 (rotation unit 37), a Y drive unit 46 (Y carriage 43), and a Z drive unit 48 (Z carriage 44), to move the blades 21A, 21B, the microscope 23, and the white light interferometer 24 relative to the table 31 and the workpiece W.

[0059] For example, before aligning the workpiece W with the blades 21A and 21B, the movement control unit 72 drives the relative movement mechanism 49 to adjust the position of the microscope 23 to a position where a predetermined alignment reference of the workpiece W can be photographed. The alignment reference here is a reference for the dicing device 10 to recognize the position of the street C (see Figure 6, etc., also called the planned division line) of the workpiece W, and for example, a recognition mark may be used.

[0060] Furthermore, when aligning the workpiece W with the blades 21A and 21B, the movement control unit 72 drives the relative movement mechanism 49 to align the blades 21A and 21B with the machining start position of the workpiece W.

[0061] Furthermore, when the workpiece W is being cut by the blades 21A and 21B, the movement control unit 72 drives the relative movement mechanism 49 to perform cutting feed of the workpiece W in the X direction, and index feed of the blades 21A and 21B in the Y direction and depth of cut feed in the Z direction.

[0062] Furthermore, when measuring the machining quality of grooves 25A and 25B (see Figures 6 and 7) formed in the workpiece W by blades 21A and 21B, the movement control unit 72, under the control of the measurement control unit 80 described later, drives the relative movement mechanism 49 to adjust the position of the white light interferometer 24 and also functions as a scanning control unit 85. This scanning control unit 85, under the control of the measurement control unit 80, performs step scanning of the white light interferometer 24 in the Z-axis direction.

[0063] The imaging control unit 74 controls the imaging of the workpiece W by the microscope 23. After the position adjustment of the microscope 23 as described above, the imaging control unit 74 causes the microscope 23 to take images of the workpiece W. As a result, the image of the workpiece W is output from the microscope 23 to the detection control unit 76.

[0064] The detection control unit 76 performs alignment detection by detecting the position of the workpiece W on street C (see Figures 6 and 7) based on the image of the workpiece W input from the microscope 23, using a known image recognition method to detect the alignment reference within the image. The detection control unit 76 then outputs the alignment detection result to the machining control unit 78.

[0065] Based on the alignment detection result from the detection control unit 76, the machining control unit 78 drives the spindles 22A, 22B and the relative movement mechanism 49 via the blade drive control unit 70 and the movement control unit 72 to perform cutting with blades 21A, 21B for each street C (see Figure 6) of the workpiece W. Here, since the dicing device 10 in this embodiment is a so-called twin-spindle dicer, the machining control unit 78 selectively executes, for example, a meeting cutting method and a step cutting method as the cutting method for the workpiece W. The selection of the cutting method is performed by the operation unit 62.

[0066] Figure 6 is an explanatory diagram illustrating the meeting cutting method. As shown in Figure 6, in the meeting cutting method, blades 21A and 21B of the same shape (same thickness) are mounted on spindles 22A and 22B. Based on the alignment detection result by the detection control unit 76, the machining control unit 78 drives the spindles 22A and 22B and the relative movement mechanism 49 via the blade drive control unit 70 and the movement control unit 72 to repeatedly perform simultaneous machining for each of the two streets C.

[0067] Simultaneous machining is a process in which two streets C are cut at once using two blades 21A and 21B of the same shape, simultaneously forming groove 25A with blade 21A and groove 25B with blade 21B. The grooves 25A and 25B formed by the meeting cutting method are so-called full-cut grooves with substantially the same shape. In the meeting cutting method, the cutting range of the workpiece W can be divided into two, and each range can be assigned to a different blade 21A and 21B, thereby shortening the machining time of the workpiece W.

[0068] Figure 7 is an explanatory diagram illustrating the step-cut method. Figure 8 is a cross-sectional view of a portion of the workpiece W cut using the step-cut method. As shown in Figures 7 and 8, the step-cut method is selected when the workpiece W is a laminate in which a low-dielectric constant insulating film (Low-k film) and a functional film that forms a circuit are laminated on the surface of a substrate such as silicon. In this step-cut method, blades 21A and 21B of different thicknesses (blades 21A and 21B of the same shape are also acceptable) are mounted on spindles 22A and 22B. Then, in the step-cut method, grooves 25A and 25B are formed for each street C by the blades 21A and 21B.

[0069] Specifically, the machining control unit 78 drives the spindles 22A, 22B and the relative movement mechanism 49 via the blade drive control unit 70 and the movement control unit 72, respectively, based on the alignment detection result from the detection control unit 76, and repeatedly executes the first machining process and the second machining process for each street C.

[0070] The first processing step involves cutting the street C with a wide blade 21A, for example, with a width of approximately 50 μm, to form a groove 25A (corresponding to the first groove of the present invention) of a predetermined depth along the street C. In the step-cut method, the groove 25A becomes a so-called half-cut groove. This removes the low-k film and the like on the street C.

[0071] The second machining process involves cutting the bottom of groove 25A with a narrow blade 21B, for example, with a width of approximately 30 μm, to form groove 25B. In the step-cut method, groove 25B becomes a so-called full-cut groove, which is narrower than groove 25A. This divides the workpiece W along the street C.

[0072] When measuring the machining quality of grooves 25A and 25B formed in the workpiece W by blades 21A and 21B, the measurement control unit 80 activates the movement control unit 72 (scanning control unit 85), the white light interferometer 24, and the interference signal acquisition unit 81.

[0073] When the step-cut method described above is selected, the measurement control unit 80 first drives the relative movement mechanism 49 via the movement control unit 72 to perform a position adjustment to move the white light interferometer 24 relative to the grooves 25A and 25B of the workpiece W along the same street C, so that the measurement light L2 can be irradiated onto them. Here, the positions of the grooves 25A and 25B formed in the workpiece W by the blades 21A and 21B are known. Therefore, the measurement control unit 80 drives the relative movement mechanism 49 to adjust the position of the white light interferometer 24 relative to the grooves 25A and 25B based on the known positions of the grooves 25A and 25B. This eliminates the need to search for the grooves 25A and 25B. However, if the grooves 25A and 25B are present within the irradiation range (spot) of the measurement light L2, for reasons such as the spot diameter of the measurement light L2 emitted from the white light interferometer 24 being sufficiently large, this position adjustment may be omitted.

[0074] Next, the measurement control unit 80 activates the scanning control unit 85 and the white light interferometer 24 to start step scanning of the white light interferometer 24 in the Z-axis direction.

[0075] Figure 9 is an explanatory diagram illustrating the step scanning of the white light interferometer 24 in the Z-axis direction. In Figure 9, to clarify each part, the relative sizes of the white light interferometer 24, grooves 25A and 25B, and step width d are ignored and some parts are exaggerated (the same applies to other figures). Also, the symbol FP in Figure 9 is the reference focal point P of the measurement light L2 where the difference in optical path length between the measurement light L2 and the reference light L3 is zero (including nearly zero), i.e., the reference focal point of the measurement light L2 where the signal intensity of the interference signal L4 is maximum.

[0076] As shown in Figure 9 (indicated by symbols IXA to IXD) and in Figure 5 described above, the scanning control unit 85, under the control of the measurement control unit 80, drives the relative movement mechanism 49 (Z drive unit 48) to perform a step scan of the white light interferometer 24 along the Z-axis direction.

[0077] Specifically, the scanning control unit 85 drives the relative movement mechanism 49 based on a predetermined scanning range and step width d (also called the number of samples or sampling rate) to repeatedly perform step movements that move the white light interferometer 24 in the Z-axis direction by a step width d within the scanning range. This allows the reference focal point FP of the measurement light L2 of the white light interferometer 24 to be step-scanned (step-moved) along the Z-axis direction. Note that there is a correlation between the step width d and the number of steps in the step scan, so determining the step width d also includes determining the number of steps.

[0078] Here, since the design values ​​for the machining shape (machining depth) of grooves 25A and 25B and the thickness of the workpiece W are known, the Z-axis positions (design values) of the front surface of the workpiece W and the bottom surfaces of grooves 25A and 25B are also known. Therefore, when performing a step scan with the white light interferometer 24, the scanning range and step width d (number of steps) of the step scan, which allows the reference focusing point FP to scan the range from the front surface of the workpiece W to the bottom surfaces of grooves 25A and 25B, can be determined in advance. The result of determining this scanning range and step width d is then set to the scanning control unit 85, for example, via the operation unit 62 or an external input interface (not shown). This allows the scanning control unit 85 to adjust the scanning range and step width d of the step scan.

[0079] At the same time, the measurement control unit 80 activates the white interferometer 24 at each step of the step scan (also called a sampling point or measurement point), that is, activates the white light source 51 and the imaging unit 56. As a result, at each step of the step scan, measurement light L2 is irradiated from the white interferometer 24 onto the grooves 25A and 25B, and the imaging unit 56 captures an interference signal L4 for each pixel and outputs the interference signal L4 to the interference signal acquisition unit 81. Alternatively, the irradiation of measurement light L2 and the capture of interference signal L4 by the white interferometer 24 may be performed continuously, and only the output of the interference signal L4 to the interference signal acquisition unit 81 may be performed intermittently at each step of the step scan.

[0080] Furthermore, if the aforementioned meeting cutting method is selected, the measurement control unit 80 controls the movement control unit 72, the scanning control unit 85, and the white light interferometer 24 to individually perform position adjustment of the white light interferometer 24, step scanning of the white light interferometer 24, and operation of the white light interferometer 24 for each step, for each groove 25A and 25B.

[0081] Returning to Figure 5, the interference signal acquisition unit 81 is connected to the imaging unit 56 of the white interferometer 24 via a communication interface (not shown). The interference signal acquisition unit 81 acquires the interference signal L4 (hereinafter abbreviated as interference signal group L5) for each pixel from the imaging unit 56 at each step of the step scan of the white interferometer 24. Hereafter, the interference signal L4 for each pixel of the imaging unit 56 acquired at each step will simply be abbreviated as "interference signal group L5".

[0082] When the aforementioned meeting cutting method is selected, the interference signal acquisition unit 81 acquires a group of interference signals L5 from the white light interferometer 24 for each groove 25A, 25B. When the aforementioned step cutting method is selected, the interference signal acquisition unit 81 acquires a group of interference signals L5 from the white light interferometer 24 corresponding to grooves 25A, 25B along the same street C. The interference signal acquisition unit 81 then outputs the group of interference signals L5 to the estimation unit 82.

[0083] Figure 10 is an explanatory diagram illustrating the estimation process of the peak position Z0 of the white light interferometer 24 by the estimation unit 82. In Figure 10, the horizontal axis represents the Z-axis position of the white light interferometer 24 during step scanning, and the vertical axis represents the signal intensity of the interference signal L4.

[0084] As shown in Figure 10 and Figure 5 described above, the estimation unit 82 estimates the peak position Z0 of the white interferometer 24 in the Z-axis direction where the intensity of the interference signal L4 peaks (maximum) for each pixel of the imaging unit 56, based on the interference signal group L5 input from the interference signal acquisition unit 81. In other words, the peak position Z0 is the position of the white interferometer 24 in the Z-axis direction where the difference in optical path length between the measurement light L2 and the reference light L3 is zero. Figure 10 illustrates the estimation of the peak position Z0 of the white interferometer 24 corresponding to any one pixel of the imaging unit 56 as an example.

[0085] First, the estimation unit 82 detects the signal intensity SG of the interference signal L4 for each step of the step scan (here, the 1st to 8th steps) corresponding to any one pixel of the imaging unit 56, based on the interference signal group L5.

[0086] Next, the estimation unit 82 calculates the peak intensity SGM of the signal intensity SG based on the signal intensity SG for each step of the step scan. As previously described, the signal intensity SG of the interference signal L4 is maximum (peak intensity SGM) when the difference in optical path length between the measurement light L2 and the reference light L3 is zero, and decreases as the absolute value of this optical path length difference increases from zero. For this reason, the estimation unit 82 can calculate the peak intensity SGM from the signal intensity SG for each step by using an estimation algorithm such as a known fitting process.

[0087] Then, the estimation unit 82 estimates the Z-axis position of the white interferometer 24 corresponding to this peak intensity SGM as the peak position Z0 of the white interferometer 24 corresponding to any one pixel as described above, based on the calculation result of the peak intensity SGM. By estimating the peak position Z0 of the white interferometer 24 based on the signal intensity SG for each step of the step scan in this way, the number of samples (sampling rate) of the step scan of the white interferometer 24 can be reduced.

[0088] Similarly, the estimation unit 82 estimates the peak position Z0 for each pixel of the imaging unit 56 and outputs the estimated peak position Z0 for each pixel to the machining quality measurement unit 83. If the previously described meeting cutting method is selected, the estimation unit 82 outputs the estimated peak position Z0 for each pixel obtained for each groove 25A, 25B to the machining quality measurement unit 83. If the previously described step cutting method is selected, the estimation unit 82 outputs the estimated peak position Z0 for each pixel corresponding to grooves 25A, 25B along the same street C to the machining quality measurement unit 83.

[0089] Returning to Figure 5, the machining quality measurement unit 83 performs a so-called kerf check to measure the machining quality (also called the machining state) of the grooves 25A and 25B formed in the workpiece W, based on the estimation result of the peak position Z0 for each pixel of the imaging unit 56 input from the estimation unit 82. In the first embodiment, the machining quality of the grooves 25A and 25B refers to the machining position of the grooves 25A and 25B, that is, the position in the Y-axis direction.

[0090] Figure 11 is an explanatory diagram illustrating the three-dimensional shape measurement of grooves 25A and 25B by the processing quality measurement unit 83. Figure 12 is an explanatory diagram illustrating the cross-sectional shape measurement of grooves 25A and 25B along the Y-axis direction by the processing quality measurement unit 83. In Figures 11 and 12, the shape measurement (kerf check) of grooves 25A and 25B formed by the step-cut method described in Figure 7, etc., is used as an example for explanation.

[0091] As shown in Figures 11, 12, and Figure 5 described above, the processing quality measurement unit 83 calculates the height of each pixel of the imaging unit 56, that is, the height in the Z-axis direction of the corresponding position on the workpiece W (inner surface of grooves 25A, 25B, and outer surface of workpiece W) corresponding to each pixel, based on the estimation result of the peak position Z0 for each pixel of the white light interferometer 24 (imaging unit 56). Since this method of calculating the height position is a known technique, a detailed explanation is omitted here. As a result, the processing quality measurement unit 83 can generate three-dimensional shape information 86 showing the three-dimensional shape of grooves 25A, 25B as shown in Figure 11. The processing quality measurement unit 83 can also generate cross-sectional shape information 88 showing the cross-sectional shape along the Y-axis direction of grooves 25A, 25B as shown in Figure 12.

[0092] Furthermore, the positional relationship between the workpiece W and the white light interferometer 24 is known based on the alignment detection result by the detection control unit 76. Therefore, the processing quality measurement unit 83 can simultaneously calculate the XY axis position coordinates of the corresponding positions on the workpiece W corresponding to each pixel of the imaging unit 56 (hereinafter referred to as workpiece corresponding position coordinates) based on the XY axis position coordinates of the white light interferometer 24 during step scanning. As a result, the processing positions of the grooves 25A and 25B within the workpiece W can be individually determined based on at least one of the three-dimensional shape information 86 and the cross-sectional shape information 88, and the workpiece corresponding position coordinates.

[0093] Figure 13 is an explanatory diagram illustrating an example of kerf checking of grooves 25A and 25B formed by a step-cut method, that is, measuring the machining position of grooves 25A and 25B within the workpiece W. As shown in Figure 13 and Figure 5 described above, the machining quality measurement unit 83 calculates the groove center position CL1 in the Y-axis direction of groove 25A within the workpiece W, and the groove center position CL2 in the Y-axis direction of groove 25B, based on at least one of the three-dimensional shape information 86 and the cross-sectional shape information 88 and the workpiece corresponding position coordinates. Groove center position CL1 corresponds to the machining position of groove 25A, and groove center position CL2 corresponds to the machining position of groove 25B.

[0094] The machining quality measurement unit 83 then outputs the measurement results of the machining position of groove 25A (groove center position CL1) and the machining position of groove 25B (groove center position CL2) to the correction value determination unit 84, the storage unit 64, and the display unit 66. As a result, the measurement results of the machining positions of grooves 25A and 25B are stored in the storage unit 64 and displayed in the display unit 66.

[0095] The correction value determination unit 84 determines a correction value Δy1 that corrects the machining position of groove 25A by blade 21A in the Y-axis direction, and a correction value Δy2 that corrects the machining position of groove 25B by blade 21B in the Y-axis direction.

[0096] Specifically, the correction value determination unit 84 has pre-set target values ​​for the machining positions of grooves 25A and 25B corresponding to the type of workpiece W, for example, the Y-axis position of street C within the workpiece W. Based on this, the correction value determination unit 84 determines the correction value Δy1 based on the measurement result of the machining position of groove 25A (groove center position CL1) by the machining quality measurement unit 83 and the target value of the machining position of groove 25A. The correction value determination unit 84 also determines the correction value Δy2 based on the measurement result of the machining position of groove 25B (groove center position CL2) by the machining quality measurement unit 83 and the target value of the machining position of groove 25B.

[0097] The correction value determination unit 84 then outputs the determined correction values ​​Δy1 and Δy2 to the machining control unit 78 described above. Based on the correction values ​​Δy1 and Δy2 input from the correction value determination unit 84, the machining control unit 78 corrects the machining position (Y-axis position) of the grooves 25A and 25B that are formed in the new street C of the workpiece W by the blades 21A and 21B.

[0098] The method for measuring the machining position (machining quality) of grooves 25A and 25B formed by the meeting cutting method, and the method for determining the correction values ​​Δy1 and Δy2, are basically the same as those for the step cutting method described above. In this case, the machining quality measurement unit 83 measures the machining position (groove center position CL1 and CL2) for each groove 25A and 25B based on the estimation results of the estimation unit 82 for each groove 25A and 25B. The correction value determination unit 84 then determines the correction values ​​Δy1 and Δy2 based on the machining position for each groove 25A and 25B.

[0099] [Operation of the First Embodiment] Figure 14 is a flowchart showing the flow of the cutting process of a workpiece W by the dicing apparatus 10 of the first embodiment, which corresponds to the control method of the workpiece processing apparatus of the present invention, and in particular the flow of the measurement process of the processing quality (processing position) of grooves 25A and 25B.

[0100] As shown in Figure 14, when the workpiece W is held by suction on the table 31, the movement control unit 72, the image capture control unit 74, and the detection control unit 76 of the overall control unit 60 are activated. As a result, the movement control unit 72 drives the relative movement mechanism 49 to adjust the position of the microscope 23, and after this position adjustment, the microscope 23 captures an alignment reference of the workpiece W under the control of the image capture control unit 74, and furthermore, the detection control unit 76 performs alignment detection based on the image of the alignment reference captured by the microscope 23 (step S1).

[0101] Once alignment detection is complete, the movement control unit 72 drives the relative movement mechanism 49 based on the alignment detection results to align the street C of the workpiece with the blades 21A and 21B.

[0102] Next, the machining control unit 78 drives each spindle 22A, 22B and the relative movement mechanism 49 via the blade drive control unit 70 and the movement control unit 72 to cut the street C with blades 21A, 21B using a meeting cutting method (see Figure 6) or a step cutting method (see Figure 7) (process S2). This forms grooves 25A, 25B along the street C. Process S2 is then repeated until measurement of the machining quality (in this case, machining position) of grooves 25A, 25B is started (NO in process S3). Alternatively, after forming the first grooves 25A, 25B, the process may proceed immediately to process S4.

[0103] When measuring the machining quality of grooves 25A and 25B is initiated (YES in step S3), the measurement control unit 80 first drives the relative movement mechanism 49 via the movement control unit 72 based on the known positions of grooves 25A and 25B to adjust the position of the white light interferometer 24 relative to grooves 25A and 25B (step S4). This allows the white light interferometer 24 to be quickly positioned in a location that allows measurement light L2 to be irradiated onto grooves 25A and 25B and corresponds to the first step (first step) of the step scanning described above in the Z-axis direction.

[0104] Once the position adjustment of the white light interferometer 24 is complete, the measurement control unit 80 activates the scanning control unit 85 and the white light interferometer 24 to start step scanning of the white light interferometer 24 in the Z-axis direction (step S5, corresponding to the scanning control step of the present invention).

[0105] First, the measurement control unit 80 activates the white light interferometer 24 (step S5A). As a result, measurement light L2 is irradiated from the white light interferometer 24 onto the grooves 25A and 25B, and the interference signal L4 for each pixel is output from the imaging unit 56 to the interference signal acquisition unit 81. As a result, the interference signal acquisition unit 81 acquires the interference signal L4 for each pixel in the first step (first step) of the step scan (step S5B, corresponding to the interference signal acquisition step of the present invention).

[0106] Next, the scanning control unit 85 drives the relative movement mechanism 49 (Z drive unit 48) to perform a step movement in which the white interferometer 24 moves in the Z-axis direction by a step width d (NO in step S5C, step S5D). This adjusts the position of the white interferometer 24 to the second step of the step scan. Then, the measurement control unit 80 activates the white interferometer 24 again (step S5A), and the interference signal acquisition unit 81 acquires the interference signal L4 for each pixel in the second step (step S5B).

[0107] Similarly, the step movement of the white interferometer 24 is repeatedly performed within the scanning range of the step scan, and with each step, the operation of the white interferometer 24 and the acquisition of the interference signal L4 for each pixel of the imaging unit 56 by the interference signal acquisition unit 81 are repeatedly performed (processes S5A to S5D). As a result, the step scan of the white interferometer 24 is completed (YES in process S5C), the interference signal acquisition unit 81 acquires the interference signal group L5, and outputs this interference signal group L5 to the estimation unit 82.

[0108] Then, based on the interference signal group L5, the estimation unit 82 performs the following calculations for each pixel of the imaging unit 56, as described in Figure 10 above: calculation of the signal intensity SG for each step of the step scan, calculation of the peak intensity SGM, and estimation of the peak position Z0 (step S6, corresponding to the estimation step of the present invention). The estimation results of the peak position Z0 for each pixel are output from the estimation unit 82 to the processing quality measurement unit 83.

[0109] By estimating the peak position Z0 for each pixel of the imaging unit 56 in this way, it becomes unnecessary to perform vertical scanning of the white interferometer 24 at a high sampling rate (fine pitch) that would allow for reliable detection of the peak position Z0, as was done in the past. As a result, step scanning (low sampling rate vertical scanning) of the white interferometer 24 can be performed.

[0110] Next, the processing quality measurement unit 83 generates either three-dimensional shape information 86 or cross-sectional shape information 88 of the grooves 25A and 25B, as shown in Figures 11 and 12, based on the estimation result of the peak position Z0 for each pixel of the imaging unit 56 by the estimation unit 82. The processing quality measurement unit 83 also calculates the workpiece corresponding position coordinates as described above, based on the alignment detection result by the detection control unit 76 and the position coordinates of the white light interferometer 24 in the XY axis direction during vertical scanning.

[0111] Then, the machining quality measurement unit 83 calculates the machining position (groove center positions CL1, CL2) of grooves 25A and 25B as the machining quality of grooves 25A and 25B, as shown in Figure 13 described above, based on at least one of the three-dimensional shape information 86 and the cross-sectional shape information 88 and the workpiece corresponding position coordinates. This completes the measurement (kerf check) of the machining position of grooves 25A and 25B (step S7, corresponding to the machining quality measurement step of the present invention). The measurement results of the machining positions of grooves 25A and 25B are output from the machining quality measurement unit 83 to the correction value determination unit 84, the storage unit 64, and the display unit 66.

[0112] In this embodiment, the processing quality of grooves 25A and 25B is measured based on the estimation result of the peak position Z0 for each pixel of the imaging unit 56 by the estimation unit 82. For this reason, in this embodiment, the measurement accuracy of the processing quality of grooves 25A and 25B is inferior to that of vertical scanning of the white light interferometer 24 at a high sampling rate (fine pitch) as described in Patent Documents 3 and 4. However, the measurement accuracy of the processing quality of grooves 25A and 25B required by the dicing device 10 is on the order of 1 μm, which is lower than the measurement accuracy requirement for surface roughness measurement, which requires measurement accuracy on the order of nm. For this reason, even if step scanning of the white light interferometer 24 is performed, the measurement performance of the processing quality of grooves 25A and 25B does not decrease, and only the benefit of faster measurement due to step scanning (low sampling) is obtained.

[0113] Furthermore, in this embodiment, the cross-sectional shape of grooves 25A and 25B can be obtained using the white light interferometer 24. Therefore, the processing position (processing quality) of grooves 25A and 25B can be measured without analyzing images of grooves 25A and 25B taken by the microscope 23, as in the conventional method. This makes it possible to accurately measure the processing position of groove 25B even when groove 25B is formed at the bottom of groove 25A, such as in a step-cut method, that is, when it is difficult to determine the processing position of groove 25B based on images taken by the microscope 23.

[0114] Furthermore, in this embodiment, a kerf check of the groove 25B formed by the actual step-cut method can be performed without performing the aforementioned step-kerf check, which involves forming the groove 25B with a narrow blade 21B on the uncut portion of the workpiece W. Therefore, the machining position of the groove 25B can be measured with high accuracy.

[0115] Once the measurement of the machining positions of grooves 25A and 25B (kerf check) is complete, the correction value determination unit 84 determines the correction values ​​Δy1 and Δy2 for the machining positions of grooves 25A and 25B based on the measurement results of the machining positions of grooves 25A and 25B (groove center positions CL1 and CL2) and the target values ​​of those machining positions (step S8). Next, the correction value determination unit 84 outputs the determination results of the correction values ​​Δy1 and Δy2 to the machining control unit 78.

[0116] Then, the machining control unit 78 drives the spindles 22A, 22B and the relative movement mechanism 49 via the blade drive control unit 70 and the movement control unit 72 based on the correction values ​​Δy1 and Δy2 to perform cutting of subsequent streets C using a meeting cutting method or a step cutting method (step S9). As a result, for each blade 21A, 21B, cutting can be performed at a position shifted by the correction values ​​Δy1 and Δy2 in the Y-axis direction from the target position (design position) of the subsequent streets C. As a result, grooves 25A and 25B can be formed with high precision along subsequent streets C.

[0117] [Effects of the First Embodiment] As described above, in the dicing apparatus 10 of the first embodiment, the white light interferometer 24 is scanned in step, and the peak position Z0 of the white light interferometer 24 is estimated for each pixel based on the interference signal group L5 acquired from the white light interferometer 24, thereby enabling the measurement of the processing quality of grooves 25A and 25B using the white light interferometer 24 to be performed in a short time. As previously stated, the benefit of increased speed due to step scanning (low sampling) is obtained without degrading the measurement performance of the processing quality of grooves 25A and 25B.

[0118] Furthermore, in the first embodiment, since the step scanning of the white light interferometer 24 can be performed using the relative movement mechanism 49 of the blade 21B (Z carriage 44 and Z drive unit 48), there is no need to provide a separate dedicated scanning mechanism, thus reducing costs. Moreover, in the first embodiment, by integrating the blade 21B and the white light interferometer 24 onto the Z carriage 44, the position adjustment of the white light interferometer 24 relative to the grooves 25A and 25B (workpieces) can be performed using a conventional alignment detection method.

[0119] [Second Embodiment] Figure 15 is an explanatory diagram illustrating the cutting process of a workpiece W by a dicing device 10 of the second embodiment and the back surface grinding of a workpiece W by a grinding (polishing) device (not shown). In the first embodiment described above, each street C is completely cut (separated) by the cutting process of the workpiece W by the dicing device 10. In contrast, as shown by the reference numeral XVA in Figure 15, in the cutting process of the workpiece W by the dicing device 10 of the second embodiment, the blades 21A and 21B do not completely cut each street C, but instead perform a so-called half-cut, leaving a certain amount of each street C uncut, thereby forming half-cut grooves 90A and 90B (corresponding to the workpiece portion). The half-cut groove 90A formed by blade 21A and the half-cut groove 90B formed by blade 21B are substantially the same shape.

[0120] Then, as shown by the symbol XVB in Figure 15, the back surface of the workpiece W is ground using a grinding device separate from the dicing device 10 to remove any remaining material, thereby completely cutting each street C as shown by the symbol XVC in Figure 15.

[0121] When the dicing device 10 performs a half-cut of each street C in this manner, if the machining depth (also called the cutting depth or cutting depth) of street C by blades 21A and 21B is insufficient, even if the back surface of the workpiece W is ground, the workpiece W cannot be cut, resulting in a cutting defect. Conversely, if street C is cut too deeply by blades 21A and 21B, the workpiece W will crack before the back surface is ground. Therefore, if the accuracy of the cutting depth of blades 21A and 21B is low, the yield will deteriorate, especially in the production of thin devices (machining of thin workpieces W).

[0122] Furthermore, the diameter of blades 21A and 21B changes due to wear, and their height in the Z-axis direction changes due to temperature changes. Therefore, high-precision control of the machining depth in the Z-axis direction of blades 21A and 21B for each street C (workpiece W) is important.

[0123] Therefore, in the dicing apparatus 10 of the second embodiment, the machining depths cz1 and cz2 (see Figure 16) of the half-cut grooves 90A and 90B formed in the workpiece W are measured using a white light interferometer 24. In the second embodiment, the machining widths cy1 and cy2 (see Figure 16) of the half-cut grooves 90A and 90B are also measured at the same time as the machining depths cz1 and cz2. Here, the machining widths cy1 and cy2 and machining depths cz1 and cz2 of the half-cut grooves 90A and 90B correspond to the machining quality (machined shape) of the workpiece in the present invention.

[0124] Since the dicing apparatus 10 of the second embodiment has basically the same configuration as the dicing apparatus 10 of the first embodiment, parts that are functionally or structurally identical to those of the first embodiment are denoted by the same reference numerals and their descriptions are omitted.

[0125] In the second embodiment, the machining control unit 78 drives each spindle 22A, 22B and the relative movement mechanism 49 via the blade drive control unit 70 and the movement control unit 72 to cut each street C of the workpiece W by simultaneous machining with blades 21A, 21B using a meeting cutting method. As a result, half-cut grooves 90A, 90B are formed for every two streets C.

[0126] In the second embodiment, the measurement control unit 80 and the scanning control unit 85 control the white interferometer 24 and the relative movement mechanism 49 to perform position adjustment of the white interferometer 24, step scanning of the white interferometer 24 and operation for each step for each half-cut groove 90A, 90B. As a result, for each half-cut groove 90A, 90B, the interference signal acquisition unit 81 of the second embodiment acquires the interference signal group L5 from the white interferometer 24, and the estimation unit 82 of the second embodiment estimates the peak position Z0 for each pixel of the imaging unit 56.

[0127] Figure 16 is an explanatory diagram illustrating the measurement of the cross-sectional shape of the half-cut grooves 90A and 90B along the Y-axis direction by the processing quality measurement unit 83 of the second embodiment. As shown in Figure 16, the processing quality measurement unit 83 of the second embodiment generates cross-sectional shape information 88 of the half-cut grooves 90A and 90B, respectively, based on the estimation result of the peak position Z0 for each pixel of the imaging unit 56 by the estimation unit 82, similar to the first embodiment.

[0128] Next, the machining quality measurement unit 83 calculates the machining width cy1 and machining depth cz1 of the half-cut groove 90A and 90B, as well as the machining width cy2 and machining depth cz2 of the half-cut groove 90B, based on the cross-sectional shape information 88 of the half-cut grooves 90A and 90B, as the machining quality (machining shape) of the half-cut grooves 90A and 90B. Here, the machining depths cz1 and cz2 are the depths in the Z-axis direction of the half-cut grooves 90A and 90B at the center positions of the machining widths cy1 and cy2, respectively. Alternatively, the machining depths cz1 and cz2 may be the depths to the lowest point in the Z-axis direction of the half-cut grooves 90A and 90B. The machining quality measurement unit 83 then outputs the measurement results of the machining depths cz1 and cz2 for each half-cut groove 90A and 90B to the correction value determination unit 84, the storage unit 64, and the display unit 66.

[0129] In the second embodiment, the correction value determination unit 84 determines a correction value Δz1 for the machining depth cz1 corresponding to the blade 21A and a correction value Δz2 for the machining depth cz2 corresponding to the blade 21B, based on the measurement results of the machining depth cz1 and cz2 by the machining quality measurement unit 83 and the target values ​​tz for the machining depth cz1 and cz2 of the half-cut grooves 90A and 90B corresponding to the type of workpiece W.

[0130] Furthermore, the correction value determination unit 84 outputs the determined correction values ​​Δz1 and Δz2 to the machining control unit 78. Based on the correction values ​​Δz1 and Δz2 input from the correction value determination unit 84, the machining control unit 78 controls the relative movement mechanism 49 and the like to correct the machining depths cz1 and cz2 of the half-cut grooves 90A and 90B formed in the new street C of the workpiece W by the blades 21A and 21B.

[0131] Furthermore, the cutting process of the workpiece W by the dicing device 10 in the second embodiment, and in particular the process of measuring the machining quality (machining depth cz1, cz2) of the half-cut grooves 90A and 90B, are basically the same as the cutting process of the first embodiment shown in Figure 14, so a detailed explanation will be omitted here.

[0132] As described above, the same effects as in the first embodiment can be obtained in the dicing apparatus 10 of the second embodiment by performing step scanning of the white light interferometer 24. Furthermore, since the cross-sectional shape of the half-cut grooves 90A and 90B can be accurately measured using the white light interferometer 24, the machining depth cz1 and cz2 (machining quality) can be accurately measured based on these measurement results.

[0133] Furthermore, since the machining depths cz1 and cz2 can be measured during the cutting process of the workpiece W by blades 21A and 21B, accurate correction values ​​Δz1 and Δz2 can be immediately applied to subsequent cutting processes in street C. Moreover, since the correction values ​​Δz1 and Δz2 can be determined each time a cutting process is performed in street C, the machining accuracy of the machining depths cz1 and cz2 for each blade 21A and 21B can be further improved.

[0134] [Third Embodiment] In each of the above embodiments, the machining quality of the workpiece, such as grooves 25A and 25B and half-cut grooves 90A and 90B, is measured, and the cutting of the workpiece W by blades 21A and 21B is corrected based on these measurement results. In contrast, in the dicing apparatus 10 of the third embodiment, the tip shape of blades 21A and 21B is measured based on the measurement results of the machining quality of the workpiece by blades 21A and 21B.

[0135] Figure 17 is a functional block diagram of the central control unit 60 of the dicing apparatus 10 of the third embodiment. As shown in Figure 17, the dicing apparatus 10 of the third embodiment has basically the same configuration as the dicing apparatus 10 of each of the above embodiments, except that the central control unit 60 functions as a blade shape measuring unit 100 instead of a correction value determination unit 84. For this reason, components that are functionally or structurally identical to those of each of the above embodiments are denoted by the same reference numerals and their descriptions are omitted.

[0136] In the third embodiment, the machining control unit 78 drives each spindle 22A, 22B and the relative movement mechanism 49 via the blade drive control unit 70 and the movement control unit 72, similar to the second embodiment, to form half-cut grooves 90A, 90B (see Figure 15) for each street C.

[0137] In the third embodiment, the measurement control unit 80, scanning control unit 85, interference signal acquisition unit 81, estimation unit 82, and processing quality measurement unit 83 function in the same manner as in the second embodiment. As a result, for each half-cut groove 90A, 90B, the following are performed: position adjustment of the white light interferometer 24, step scanning of the white light interferometer 24 and operation for each step, acquisition of the interference signal group L5, estimation of the peak position Z0, and measurement of the cross-sectional shape.

[0138] Figure 18 is an explanatory diagram illustrating the measurement of the cross-sectional shape of the half-cut grooves 90A and 90B by the machining quality measurement unit 83 of the third embodiment. As shown in Figure 18, the machining quality measurement unit 83 of the third embodiment generates cross-sectional shape information 88 for the half-cut grooves 90A and 90B based on the estimation results of the estimation unit 82, similar to the second embodiment, and outputs the cross-sectional shape information 88 for each half-cut groove 90A and 90B to the blade shape measurement unit 100.

[0139] The blade shape measuring unit 100 measures the tip shapes of blades 21A and 21B based on the measurement results (cross-sectional shape information 88) of the cross-sectional shape of each half-cut groove 90A and 90B input from the processing quality measuring unit 83. Since the tip shapes of blades 21A and 21B are transferred to the bottom of the half-cut grooves 90A and 90B, respectively, the tip shapes of blades 21A and 21B can be measured from the cross-sectional shapes of the half-cut grooves 90A and 90B. The measurement results of the tip shapes of blades 21A and 21B by the blade shape measuring unit 100 are stored in the storage unit 64 and displayed in the display unit 66.

[0140] [Operation of the third embodiment] Figure 19 is a flowchart showing the flow of the measurement process for the tip shapes of blades 21A and 21B by the dicing device 10 of the third embodiment, which corresponds to the control method of the workpiece processing device of the present invention. As shown in Figure 19, similar to the first embodiment (see Figure 14), alignment detection (process S1) and cutting of each street C using the meeting cutting method (process S2) are performed, and half-cut grooves 90A and 90B are formed along each street C.

[0141] When measurement of the tip shapes of blades 21A and 21B is initiated (YES in step S3A), the processes from step S4 to step S7A are executed in the same manner as in the first embodiment described above. Specifically, for each half-cut groove 90A and 90B, the position adjustment of the white light interferometer 24 (step S4), step scanning of the white light interferometer 24 (step S5), and estimation of the peak position Z0 (step S6) are performed. Then, the processing quality measurement unit 83 performs measurement of the cross-sectional shape of the half-cut grooves 90A and 90B (generation of cross-sectional shape information 88) based on the estimation result of the peak position Z0 for each half-cut groove 90A and 90B by the estimation unit 82 (step S7A).

[0142] Next, the blade shape measuring unit 100 measures the tip shapes of blades 21A and 21B based on the cross-sectional shape information 88 of the half-cut grooves 90A and 90B, and outputs the measurement results of the tip shapes of blades 21A and 21B to the storage unit 64 and the display unit 66 (step S10). As a result, the measurement results of the tip shapes of blades 21A and 21B are stored in the storage unit 64 and displayed in the display unit 66.

[0143] The operator determines the wear condition of each blade 21A and 21B based on the measurement results of the tip shapes of the blades 21A and 21B displayed on the display unit 66, and determines whether or not replacement of the blades 21A and 21B is necessary. Alternatively, the wear condition of each blade 21A and 21B, and the determination of whether or not replacement is necessary, may be performed automatically by the central control unit 60.

[0144] As described above, in the dicing apparatus 10 of the third embodiment, by performing step scanning of the white light interferometer 24, the cross-sectional shape (processing quality) of the half-cut grooves 90A and 90B using the white light interferometer 24 can be measured in a short time. As a result, the tip shape of the blades 21A and 21B can be measured in a short time.

[0145] Furthermore, since the cross-sectional shape of the half-cut grooves 90A and 90B can be accurately measured using the white light interferometer 24, the wear state of the tip shape of the blades 21A and 21B and the progression of wear can be accurately determined. This allows the operator to be prompted to replace the blades 21A and 21B, or to truing (shape correction of the blades 21A and 21B), or dressing (sharpening and resharpening the blades 21A and 21B) before the processing quality of the workpiece W falls below the acceptable level and defects occur.

[0146] Furthermore, in the dicing apparatus 10 of the third embodiment, it becomes possible to measure the tip shape of the blades 21A and 21B during the cutting process of the workpiece W by the blades 21A and 21B. As a result, the productivity of the dicing apparatus 10 can be improved compared to the conventional method.

[0147] [Fourth Embodiment] Figure 20 is an explanatory diagram illustrating the step scanning of the white light interferometer 24 by the dicing apparatus 10 of the fourth embodiment. Figure 21 is an enlarged view of the grooves 25A and 25B in Figure 20 and is a diagram illustrating the position of the reference focal point FP of the measurement light L2 for each step of the step scanning in the fourth embodiment. In Figures 20 and 21, the explanation will be given using the case where the grooves 25A and 25B are formed using a step-cut method as an example.

[0148] In the dicing apparatus 10 of each of the above embodiments, the step width d for each step of the step scan of the white light interferometer 24 is constant. However, the dicing apparatus 10 of the fourth embodiment has a function to individually adjust the step width d for each step of the step scan. Since the dicing apparatus 10 of the fourth embodiment has basically the same configuration as the dicing apparatus 10 of each of the above embodiments, the same reference numerals are used for parts that are functionally or structurally identical to those in each of the above embodiments, and their descriptions are omitted.

[0149] In the fourth embodiment, the step width d for each step of the step scan of the white light interferometer 24 is set in the scan control unit 85 via the operation unit 62, etc. This allows the scan control unit 85 to arbitrarily adjust the step width d for each step of the step scan.

[0150] For example, as shown in Figures 20 and 21, in the fourth embodiment, the scanning range of the step scan of the white light interferometer 24 is divided into a first scanning range SR1, a second scanning range SR2, and a third scanning range SR3, depending on the location of the grooves 25A and 25B (location of the workpiece). The first scanning range SR1 is the scanning range in which the reference focusing point FP of the measurement light L2 emitted from the white light interferometer 24 scans the front surface of the workpiece W and the bottom of the groove 25A. The second scanning range SR2 is the scanning range in which the reference focusing point FP scans the bottom of the groove 25B. The third scanning range SR3 is the scanning range between the first scanning range SR1 and the second scanning range SR2.

[0151] Furthermore, if grooves 25A and 25B are formed by the meeting cutting method, the first scanning range SR1 is the scanning range in which the reference focusing point FP scans the front surface of the workpiece W. The second scanning range SR2 is the scanning range in which the reference focusing point FP scans the bottom of groove 25A or groove 25B.

[0152] In the fourth embodiment, the step width d of each step in the step scan is set narrowly in the ranges corresponding to the first scanning range SR1 and the second scanning range SR2, while conversely, the step width d of each step is set wider in the range corresponding to the third scanning range SR3. As a result, in the parts that are important for measuring the machining quality of grooves 25A and 25B (the front surface of the workpiece W and the bottom of grooves 25A and 25B), the step scan of the white light interferometer 24 is performed at a high sampling rate, thereby improving the measurement accuracy of the machining quality of grooves 25A and 25B. Conversely, in the parts that do not significantly affect the measurement of the machining quality of grooves 25A and 25B, the step scan of the white light interferometer 24 is performed at a low sampling rate, so that the measurement of the machining quality of grooves 25A and 25B can be performed in a shorter time. As a result, the machining quality of grooves 25A and 25B can be measured quickly and accurately.

[0153] Note that the step width d for each scanning range SR1 to SR3 is not limited to the examples shown in Figures 20 and 21, but can be adjusted arbitrarily. For example, the step width d may be different for each scanning range SR1 to SR3. Also, depending on the type of groove 25A, 25B (workpiece), the scanning range of the step scan may be divided into 2 or 4 or more.

[0154] [others] In each of the above embodiments, the dicing device 10 is provided with a pair of blades 21A, 21B and a pair of spindles 22A, 22B, but the number of blades and spindles (i.e., the number of processing heads of the present invention) may be 1 or 3 or more.

[0155] In the embodiments described above, a twin-spindle dicer (a pair of blades 21A, 21B and a pair of spindles 22A, 22B) was used as an example of the processing head of the present invention. However, the present invention can also be applied when one or more laser processing heads for performing laser processing (including ablation groove processing) on ​​the workpiece W are provided in the dicing device 10.

[0156] In each of the above embodiments, a white light interferometer 24 is provided on one of the pair of Z carriages 44 (one of the twin spindles) and a microscope 23 is provided on the other of the pair of Z carriages 44 (the other of the twin spindles). However, a white light interferometer 24 may also be provided on the other Z carriage 44 (the other of the twin spindles). Similarly, a microscope 23 may also be provided on one of the Z carriages 44. In other words, a microscope 23 and a white light interferometer 24 may be provided for each of the multiple Z carriages 44. Furthermore, in each of the above embodiments, the Z carriage 44 performs the step scanning described above by stepping the white light interferometer 24 in the Z-axis direction. However, it is sufficient that the white light interferometer 24 can be step scanned relative to the table 31. For example, step scanning may be performed by stepping the table 31 in the Z-axis direction.

[0157] In the embodiments described above, the white light interferometer 24 is mounted on the Z carriage 44, allowing the blade 21B and the white light interferometer 24 to be scanned together in the Z-axis direction. However, the white light interferometer 24 may be mounted separately from the blade 21B and the Z carriage 44. In this case, a separate actuator (carriage) capable of scanning the white light interferometer 24 in the Z-axis direction is provided.

[0158] In each of the above embodiments, the processing quality [processing position, processing shape (including cross-sectional shape)] of various workpiece parts such as grooves 25A, 25B and half-cut grooves 90A, 90B formed on the workpiece W by blades 21A, 21B is measured using a white light interferometer 24. However, the processing quality of workpiece parts formed on the workpiece W by other devices may be measured using the dicing device 10.

[0159] For example, if the workpiece W is a laminate in which a low-k film or the like is laminated on a silicon substrate, the workpiece W is first subjected to laser processing using laser light at each street C by a laser processing device (not shown). This creates laser-processed grooves (laser grooves) at each street C. Then, the dicing device 10 measures the processing quality (center position of the processing width) of the laser-processed grooves using a white light interferometer 24, and based on this measurement result, the bottom of each laser-processed groove is cut by simultaneous processing with blades 21A and 21B using a meeting cutting method.

[0160] In each of the above embodiments, the dicing apparatus 10 is equipped with a Mirau-type white light interferometer 24, but any known type of white light interferometer 24, such as a Michelson-type or Fizeau-type, may be provided.

[0161] The dicing apparatus 10 of each of the above embodiments may be combined as appropriate. For example, the dicing apparatus 10 of the first and second embodiments may be combined to simultaneously measure both the processing position and the processing shape as processing quality of various workpieces. Alternatively, the dicing apparatus 10 of the first and second embodiments and the dicing apparatus 10 of the third embodiment may be combined as appropriate to enable both processing quality measurement of various workpieces and measurement of the tip shapes of the blades 21A and 21B.

[0162] In the embodiments described above, the measurement of the processing quality of grooves 25A, 25B and half-cut grooves 90A, 90B was used as an example to explain the workpiece parts of the present invention. However, the present invention can also be applied to measuring the processing quality of various workpiece parts formed on the workpiece W by the dicing device 10 or other devices. [Explanation of Symbols]

[0163] 10…Dicing device, 21A,21B…Blade, 22A,22B…Spindle, 23…Microscope, 24…White light interferometer, 25A,25B…Groove, 31…Table, 49…Relative movement mechanism, 51…White light source, 56…Imaging unit, 60…General control unit, 70…Blade drive control unit, 72…Movement control unit, 74…Imaging control unit, 76…Detection control unit, 78…Processing control unit, 80…Measurement control unit, 81…Interference signal acquisition unit, 82…Estimation unit, 83…Processing quality Measurement unit, 84...Correction value determination unit, 86...Three-dimensional shape information, 88...Cross-sectional shape information, 90A, 90B...Half-cut groove, 100...Blade shape measurement unit, C...Street, CL1, CL2...Groove center position, cy1, cy2...Machining width, cz1, cz2...Machining depth, FP...Reference focusing point, L1...White light, L2...Measurement light, L3...Reference light, L4...Interference signal, L5...Interference signal group, W...Workpiece, Δy1, Δy2, Δz1, Δz2...Correction value, Z0...Peak position

Claims

[Claim 1] A table that holds the workpiece, A machining head for machining the workpiece held in the table, A relative movement mechanism for moving the machining head relative to the table, A white light interferometer provided integrally with the processing head, which emits white light toward a workpiece formed on the workpiece and detects an interference signal between the white light reflected by the workpiece and the white light reflected by a reference plane, A scanning control unit drives the relative movement mechanism to scan the processing head and the white light interferometer together in a direction perpendicular to the table, thereby changing the optical path length of the white light reflected from the workpiece, An interference signal acquisition unit intermittently acquires the interference signal from the white light interferometer during the scan, Based on the interference signal acquired by the interference signal acquisition unit, an estimation unit estimates the position of the white light interferometer where the intensity of the interference signal peaks. An interference signal measuring device equipped with the following features.

Images