Processing equipment

Abstract

To provide a processing device that can detect the position of the chuck table with high precision. [Solution] The processing apparatus 2 comprises a chuck table 4, a processing means 6, an X-axis feed means 8 for processing and feeding the chuck table 4 in the X-axis direction, an illumination means 12 for irradiating light into the movable range of the chuck table 4, an imaging means 14 for acquiring an image within the movable range of the chuck table 4, and a moiré fringe generation mechanism 16. The moiré fringe generation mechanism 16 includes a grid chart in which reflective parts that reflect light and non-reflective parts that absorb light are alternately formed at first equal intervals, a photomask in which transmissive parts that transmit light and shielding parts that block light are alternately formed at equal intervals, and a projection lens for projecting light that has passed through the photomask onto the grid chart at second equal intervals. The processing apparatus 2 makes the first equal intervals and the second equal intervals different so as to generate moiré fringes, and the moiré fringes are imaged by the imaging means 14 to detect the position of the chuck table 4 in the X-axis direction.

Description

Technical Field

[0004] , , , , , , , , , , , , ,

[0005]

[0001] The present invention relates to a processing apparatus including at least a chuck table for holding a workpiece and a processing means for processing the workpiece held on the chuck table.

Background Art

[0002] A wafer on which a plurality of devices such as ICs and LSIs are partitioned by a dicing line and formed on the surface is divided into individual device chips by a dicing apparatus or a laser processing apparatus, and each of the divided device chips is used in an electric device such as a mobile phone or a personal computer.

[0003] The dicing apparatus includes a chuck table for holding a wafer, a cutting means for cutting the wafer held on the chuck table, an X-axis feed means for feeding the chuck table in the X-axis direction, and a Y-axis feed means for feeding the cutting means in the Y-axis direction, and can divide the wafer into individual device chips with high precision (see, for example, Patent Document 1).

[0004] Further, the laser processing apparatus includes a chuck table for holding a wafer, a laser beam irradiation means for irradiating the wafer held on the chuck table with a laser beam, an X-axis feed means for feeding the chuck table in the X-axis direction, and a Y-axis feed means for feeding the chuck table in the Y-axis direction, and can divide the wafer into individual device chips with high precision (see, for example, Patent Document 2).

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0006] The X-axis and Y-axis feed mechanisms, which position the chuck table in a predetermined location, detect the origin of movement and control the X and Y coordinates of the chuck table from that origin. However, when encoders or linear scales are used to detect the origin, the encoder method and some linear scale methods control the movement based on the distance from the sensor end using a photointerrupter. This necessitates returning the chuck table to the sensor end each time initial settings are performed, resulting in poor productivity.

[0007] Furthermore, if a camera is installed to view the entire inside of the device and the position of the chuck table is detected by image processing, it is not necessary to return the chuck table to the sensor end. However, even if the image sensor built into the camera has a resolution of 5 μm pixels, when imaging a relatively wide area such as the movable range of the chuck table, the area captured by a single pixel becomes about 100 times wider. As a result, the effective resolution becomes an accuracy of about 500 μm, which presents a problem in that the position of the chuck table cannot be detected with high accuracy.

[0008] The objective of the present invention is to provide a processing apparatus that can prevent a decrease in productivity by eliminating the need to return the chuck table to the sensor end each time initial settings are performed, and that can detect the position of the chuck table with high precision. [Means for solving the problem]

[0009] According to the present invention, the following processing apparatus is provided that solves the above problems. That is, A processing apparatus comprising at least a chuck table for holding a workpiece, and processing means for processing the workpiece held on the chuck table, The system comprises an X-axis feed means for machining feed of the chuck table in the X-axis direction, an illumination means for irradiating light into the movable range of the chuck table, an imaging means for acquiring an image within the movable range of the chuck table, and a moiré fringe generation mechanism. The moiré pattern generation mechanism is, A grid chart is provided adjacent to the chuck table, in which reflective sections that reflect light and non-reflective sections that absorb light are formed alternately at first equal intervals, A photomask is provided for the lighting means, having light-transmitting portions and light-blocking portions formed alternately at equal intervals, The system includes a projection lens that projects light that has passed through the photomask onto the grid chart at second equal intervals, A processing apparatus is provided in which the first equal interval and the second equal interval are made slightly different so as to generate moiré fringes, and the moiré fringes are imaged by the imaging means to detect the position of the chuck table in the X-axis direction.

[0010] Preferably, if the resolution of the imaging means is W0 (μm), then let the first equal interval be W1 (μm) and the second equal interval be W0 (μm), and let W1 (μm) = W0 (μm) + x (μm). When the chuck table is moved by x (μm) by the X-axis feed means, the moiré fringes will move by W0 (μm), and the resolution of the imaging means will be x (μm).

[0011] The imaging means comprises a first image processing unit and a second image processing unit. Preferably, the first image processing unit detects the position of the chuck table in the X-axis direction with a resolution of W0 (μm) by pattern matching between a pre-registered registered image and an captured image, and the second image processing unit detects the position of the chuck table in the X-axis direction with a resolution of x (μm) by the movement of moiré fringes.

[0012] The system may further include a Y-axis feed means for machining the chuck table in the Y-axis direction perpendicular to the X-axis direction, and the imaging means may be used to capture moiré patterns and detect the position of the chuck table in the Y-axis direction. [Effects of the Invention]

[0013] The processing apparatus of the present invention is A processing apparatus comprising at least a chuck table for holding a workpiece, and processing means for processing the workpiece held on the chuck table, The system comprises an X-axis feed means for machining feed of the chuck table in the X-axis direction, an illumination means for irradiating light into the movable range of the chuck table, an imaging means for acquiring an image within the movable range of the chuck table, and a moiré fringe generation mechanism. The moiré pattern generation mechanism is, A grid chart is provided adjacent to the chuck table, in which reflective sections that reflect light and non-reflective sections that absorb light are formed alternately at first equal intervals, A photomask is provided for the lighting means, having light-transmitting portions and light-blocking portions formed alternately at equal intervals, The system includes a projection lens that projects light that has passed through the photomask onto the grid chart at second equal intervals, The first and second equal intervals are made slightly different so that moiré patterns are generated, and these moiré patterns are captured by the imaging means to detect the position of the chuck table in the X-axis direction. This eliminates the need to return the chuck table to the sensor end each time initial settings are performed, preventing a decrease in productivity, and allows for highly accurate detection of the chuck table's position. [Brief explanation of the drawing]

[0014] [Figure 1] A perspective view of the processing apparatus according to the present invention. [Figure 2] A schematic diagram of the lighting means shown in Figure 1. [Figure 3] A schematic diagram of the imaging means shown in Figure 1. [Figure 4] (a) Perspective view of the grid chart shown in Figure 1, (b) Enlarged plan view of the grid chart shown in (a). [Figure 5](a) Schematic diagram showing the light intensity of moiré fringes at the initial position of the chuck table, (b) Schematic diagram showing the light intensity of moiré fringes when the chuck table moves 125 μm from the initial position, (c) Schematic diagram showing the light intensity of moiré fringes when the chuck table moves 250 μm from the initial position, (d) Schematic diagram showing the light intensity of moiré fringes when the chuck table moves 375 μm from the initial position.

Embodiments for Carrying out the Invention

[0015] Hereinafter, a preferred embodiment of the processing apparatus according to the present invention will be described with reference to the drawings.

[0016] (Processing apparatus 2) In FIG. 1, the processing apparatus indicated by reference numeral 2 as a whole includes a chuck table 4 for holding a workpiece such as a semiconductor wafer, a processing means 6 for processing the workpiece held by the chuck table 4, an X-axis feed means 8 for feeding the chuck table 4 in the X-axis direction for processing, a Y-axis feed means 10 for feeding the chuck table 4 in the Y-axis direction for processing, an illumination means 12 for irradiating light in the movable range of the chuck table 4, an imaging means 14 for acquiring an image in the movable range of the chuck table 4, and a moiré fringe generation mechanism 16. Here, the X-axis direction is the direction indicated by arrow X in FIG. 1, and the Y-axis direction is the direction indicated by arrow Y in FIG. 1 and is perpendicular to the X-axis direction. The XY plane defined by the X-axis direction and the Y-axis direction is substantially horizontal.

[0017] (Chuck table 4) A circular suction chuck 18 is disposed at the upper end of the chuck table 4. The suction chuck 18 is formed of a porous member such as porous ceramics. The suction chuck 18 is also connected to a suction means (not shown). In the chuck table 4, a suction force is generated on the upper surface of the suction chuck 18 by the suction means, and the workpiece placed on the upper surface of the suction chuck 18 is sucked and held. A plurality of clamps 20 are arranged at intervals in the circumferential direction on the periphery of the chuck table 4.

[0018] Furthermore, the chuck table 4 is configured to be movable in the X-axis and Y-axis directions. The processing apparatus 2 of this embodiment includes a base 22, an X-axis movable plate 24 mounted on the upper surface of the base 22 so as to be movable in the X-axis direction, a Y-axis movable plate 26 mounted on the upper surface of the X-axis movable plate 24 so as to be movable in the Y-axis direction, a support column 28 fixed to the upper surface of the Y-axis movable plate 26, and a cover plate 30 fixed to the upper end of the support column 28. The cover plate 30 has an elongated hole 30a extending in the Y-axis direction. The chuck table 4 is mounted on the upper end of the support column 28 through the elongated hole 30a of the cover plate 30. Therefore, the chuck table 4 is configured to be movable in the X-axis and Y-axis directions via the X-axis movable plate 24 and the Y-axis movable plate 26. The chuck table 4 is also rotated about the vertical axis by a motor (not shown) built into the support column 28.

[0019] (Processing means 6) The processing means 6 in this embodiment is a laser beam irradiation means for performing laser processing on a workpiece held on the chuck table 4. The processing means 6 includes a housing 32 that extends upward from the upper surface of the base 22 and then substantially horizontally. An oscillator (not shown) that emits a laser beam is housed inside the housing 32. A concentrator 34 is mounted on the lower tip of the housing 32 to focus the laser beam emitted by the oscillator and irradiate the workpiece held on the chuck table 4, and an alignment means 35 is mounted to image the workpiece held on the chuck table 4 and detect the area to be laser processed. Note that the processing means 6 is not limited to a laser beam irradiation means, and may be, for example, a cutting means equipped with a rotatable cutting blade for performing cutting on a workpiece held on the chuck table 4.

[0020] (X-axis feed mechanism 8) The X-axis feed mechanism 8 includes a ball screw 36 connected to the X-axis movable plate 24 and extending in the X-axis direction, and a stepping motor 38 that rotates the ball screw 36. The X-axis feed mechanism 8 converts the rotational motion of the stepping motor 38 into linear motion using the ball screw 36 and transmits it to the X-axis movable plate 24, moving the X-axis movable plate 24 in the X-axis direction along the guide rail 22a on the base 22. As a result, the chuck table 4 is fed for machining in the X-axis direction.

[0021] (Y-axis feed mechanism 10) The Y-axis feed mechanism 10 includes a ball screw 40 connected to the Y-axis movable plate 26 and extending in the Y-axis direction, and a stepping motor 42 that rotates the ball screw 40. The Y-axis feed mechanism 10 converts the rotational motion of the stepping motor 42 into linear motion using the ball screw 40 and transmits it to the Y-axis movable plate 26, moving the Y-axis movable plate 26 in the Y-axis direction along the guide rail 24a on the X-axis movable plate 24. As a result, the chuck table 4 is fed for machining in the Y-axis direction.

[0022] (Lighting means 12) The illumination means 12 includes a case 44 (see Figures 1 and 2) mounted on the lower front end of the housing 32, and a light source 46 (see Figure 2) built into the case 44. The case 44 of the illumination means 12 in this embodiment is equipped with a photomask 60 and a projection lens 62 of the moiré fringe generation mechanism 16. The light from the light source 46 of the illumination means 12 passes through the photomask 60 and projection lens 62 and then irradiates the movable range of the chuck table 4. In other words, the illumination means 12 is designed to illuminate the entire movable range of the chuck table 4. The movable range of the chuck table 4 (movable range in the XY plane) can be set to, for example, 1000 mm × 1000 mm.

[0023] (Imaging means 14) The imaging means 14 includes a case 48 (see Figures 1 and 3) attached to the lower front end of the housing 32, an image sensor 50 (see Figure 3) built into the case 48, and an imaging lens 52 (see Figure 3) that reduces and forms an image of the subject on the image sensor 50. The field of view size (size in the XY plane) of the imaging means 14 is set to be greater than or equal to the movable range of the chuck table 4. Therefore, the imaging means 14 can image the chuck table 4 regardless of its position within the movable range of the chuck table 4.

[0024] Furthermore, as shown in Figure 3, the imaging means 14 of this embodiment includes a first image processing unit 54 and a second image processing unit 56. The first image processing unit 54 detects the position of the chuck table 4 in the X-axis direction and the Y-axis direction with a resolution of W0 (μm) by pattern matching between a pre-registered registered image and an captured image. If the resolution W0 (μm) of the first image processing unit 54 is, for example, 500 μm, then the imaging means 14 in the case of a resolution W0 (μm) of the first image processing unit 54 may be, for example, one with a field of view size of 1000 mm × 1000 mm, an image sensor 50 size of 10 mm × 10 mm, an image sensor 50 pixel count of 2000 × 2000, a pixel size of 5 μm × 5 μm, and an imaging lens 52 magnification of 1 / 100. The second image processing unit 56 detects the position of the chuck table 4 in the X-axis direction and the Y-axis direction with a resolution of x (μm) by the movement of moiré fringes, which will be described later. The resolution x (μm) of the second image processing unit 56 is smaller than the resolution W0 (μm) of the first image processing unit 54, and can be, for example, around 5 μm.

[0025] (Moire pattern generation mechanism 16) The moiré fringe generation mechanism 16 includes a grid chart 58 (see Figures 1 and 4), a photomask 60 (see Figure 2), and a projection lens 62 (see Figure 2).

[0026] (Grid chart 58 of moiré fringe generation mechanism 16) As shown in Figures 1 and 4, the grid chart 58 is positioned adjacent to the chuck table 4 to such an extent that it can be illuminated by the illumination means 12 and imaged by the imaging means 14, regardless of the position of the chuck table 4. In this embodiment, the grid chart 58 is positioned on the upper surface of the cover plate 30.

[0027] As shown in Figure 4(b), the grid chart 58 has reflective portions 64 that reflect light and non-reflective portions 66 that absorb light. The reflective portions 64 and non-reflective portions 66 are formed alternately at a first equal interval (for example, 505 μm). The grid chart 58 may be made of, for example, a light-reflecting diffusing material such as ceramic, on which a metal film is deposited or a coating is applied. The parts without the metal film or coating become the reflective portions 64, and the parts with the metal film or coating become the non-reflective portions 66. The number of reflective portions 64 and non-reflective portions 66 may be such that at least one node of moiré fringes is generated on the grid chart 58 (for example, 99).

[0028] Furthermore, as shown in Figure 4(a), the grid chart 58 of this embodiment has an X-axis grid chart 58a in which reflective portions 64 and non-reflective portions 66 are alternately formed in the X-axis direction, and a Y-axis grid chart 58b in which reflective portions 64 and non-reflective portions 66 are alternately formed in the Y-axis direction. The X-axis grid chart 58a and the Y-axis grid chart 58b have different alignment directions for the reflective portions 64 and non-reflective portions 66 in the X-axis direction and the Y-axis direction, but their respective configurations are common.

[0029] (Photomask 60 of moiré fringe generation mechanism 16) As shown in Figure 2, the photomask 60 is installed in the case 44 of the illumination means 12. The photomask 60 has a light-transmitting portion 68 and a light-blocking portion 70. The light-transmitting portion 68 and the light-blocking portion 70 are formed alternately at equal intervals (for example, 5 μm). The photomask 60 may be made of a light-transmitting material such as a glass plate with a metal film such as chromium (Cr) deposited on it, where the parts without the metal film become the light-transmitting portion 68 and the parts with the metal film become the light-blocking portion 70. The photomask 60 is also configured to be rotatable and can be positioned in a first position in the X-axis direction where the light-transmitting portion 68 and the light-blocking portion 70 are arranged alternately, and in a second position in the Y-axis direction where the light-transmitting portion 68 and the light-blocking portion 70 are arranged alternately.

[0030] Alternatively, instead of the photomask 60, a spatial light modulator (SLM) may be provided that generates an image in which transparent portions 68 and shielding portions 70 are alternately formed at equal intervals in the X-axis direction, and an image in which transparent portions 68 and shielding portions 70 are alternately formed at equal intervals in the Y-axis direction. Examples of spatial light modulators include transmissive liquid crystal panels, reflective liquid crystal panels, and digital micromirror devices.

[0031] (Projection lens 62 of moiré fringe generation mechanism 16) Continuing the explanation with reference to Figure 2, the projection lens 62 is located in the case 44 of the illumination means 12 and is positioned further from the light source 46 than the photomask 60. The projection lens 62 projects the light from the light source 46 that has passed through the photomask 60 onto the grid chart 58 at a second equal interval. The magnification of the projection lens 62 is, for example, about 100 times. The second equal interval is slightly different from the first equal interval to the extent that moiré fringes are generated when the light from the light source 46 that has passed through the photomask 60 is projected onto the grid chart 58. For example, if the first equal interval is 505 μm, the second equal interval can be 500 μm. In Figure 2, the light projected onto the grid chart 58 at the second equal interval is indicated by the symbol 72 (bright lines: 72a, dark lines: 72b).

[0032] (Detection of the position of chuck table 4) Next, a method for detecting the X-axis and Y-axis positions of the chuck table 4 in the processing apparatus 2 described above will be explained. In this embodiment, an example will be described in which the X-axis position of the chuck table 4 is detected, and then the Y-axis position of the chuck table 4 is detected.

[0033] When detecting the position of the chuck table 4 in the X-axis direction, first, moiré patterns are generated on the X-axis grid chart 58a. At this time, the photomask 60 is positioned in a first position so that the transparent portion 68 and the shielding portion 70 of the photomask 60 are arranged alternately in the X-axis direction. Next, light is shone from the light source 46 of the illumination means 12. The light shone from the light source 46 passes through the photomask 60 and projection lens 62 of the moiré pattern generation mechanism 16 and shines on the movable range of the chuck table 4. As a result, since the photomask 60 is positioned in a first position, the light that has passed through the projection lens 62 is projected onto the X-axis grid chart 58a at second equal intervals in the X-axis direction. As described above, the first and second equivalence intervals are slightly different in degree to which moiré fringes are generated. Therefore, when light transmitted through the projection lens 62 is projected onto the X-axis grid chart 58a at the second equivalence interval in the X-axis direction, moiré fringes with a larger period than the first and second equivalence intervals are generated on the X-axis grid chart 58a.

[0034] After generating moiré patterns on the X-axis grid chart 58a, the imaging means 14 captures images of the movable range of the chuck table 4. In this embodiment, as described above, when the imaging means 14 captures images of the movable range of the chuck table 4, an image of the chuck table 4 can be obtained regardless of its position. Furthermore, when the imaging means 14 captures images of the movable range of the chuck table 4, images of the moiré patterns generated on the X-axis grid chart 58a can also be obtained. When acquiring images of the moiré patterns, the imaging means 14 captures images while the chuck table 4 is moved by the X-axis feed means 8, thereby acquiring images of multiple moiré patterns.

[0035] After capturing the movable range of the chuck table 4, the first image processing unit 54 roughly detects the position of the chuck table 4 in the X-axis direction (with a resolution of W0 (500 μm) in this embodiment) by pattern matching the acquired captured image of the chuck table 4 with a pre-registered image.

[0036] After roughly detecting the position of the chuck table 4 in the X-axis direction, the second image processing unit 56 detects the position of the chuck table 4 in the X-axis direction with a resolution finer than 500 μm. In this process, first, the acquired images of multiple moiré fringes are processed to determine the relationship between the light intensity of the moiré fringes and the position in the X-axis direction (see Figures 5(a) to 5(d)). Next, based on the relationship between the light intensity of the moiré fringes and the position in the X-axis direction, the relationship between the amount of movement of the chuck table 4 and the position of the moiré fringes is determined. The amount of movement of the chuck table 4 can be determined from the electrical signal input to the stepping motor 38 of the X-axis feed means 8. The position of the moiré fringes can be determined, for example, by using the nodes of the moiré fringes with weak light intensity (the parts indicated by the symbol A in Figures 5(a) to 5(d)) as measurement points. Then, the second image processing unit 56 detects the position of the chuck table 4 in the X-axis direction with high precision based on the relationship between the amount of movement of the chuck table 4 and the position of the moiré fringes.

[0037] Since the moiré fringes move by a larger amount than the movement of the chuck table 4, the second image processing unit 56 can detect the position of the chuck table 4 in the X-axis direction with high accuracy based on multiple images in which the movement of the moiré fringes is captured. For example, if the resolution of the first image processing unit 54 is W0 (500 μm), then the first equal interval for the reflective portion 64 and non-reflective portion 66 of the grid chart 58 is set to W1 (505 μm), and the second equal interval for the bright fringes 72a and dark fringes 72b of light projected onto the grid chart 58 is set to W0 (500 μm). If W1 (μm) = W0 (μm) + x (5 μm), then when the chuck table 4 is moved by x (μm) by the X-axis feed means 8, the moiré fringes will move by W0 (μm), and the resolution of the second image processing unit 56 of the imaging means 14 will be x (μm). Specifically, if W0 = 500 μm, W1 = 505 μm, and x = 5 μm, and the chuck table 4 is moved 5 μm in the X-axis direction by the X-axis feed means 8, the moiré fringes will move 500 μm in the X-axis direction. In this way, a small movement of about 5 μm of the chuck table 4 in the X-axis direction is detected as a large movement of about 500 μm of the moiré fringes in the X-axis direction. Therefore, the second image processing unit 56 can detect the position of the chuck table 4 in the X-axis direction with high accuracy based on multiple images in which the movement of the moiré fringes is captured.

[0038] The relationship between the amount of movement of the chuck table 4 shown in Figures 5(a) to 5(d) and the position of the moiré fringes is as follows, for example. In the following example, the moiré fringes move by an amount 100 times the amount of movement of the chuck table 4. Drawing: Chuck table travel distance, position of moiré pattern nodes. Figure 5(a) 0 μm X0 = 250.0 mm Figure 5(b) 125 μm X1 = 237.5 mm Figure 5(c) 250 μm X² = 225.0 mm Figure 5(d) 375 μm X3 = 212.5 mm

[0039] After detecting the position of the chuck table 4 in the X-axis direction, the chuck table 4 can be positioned with high precision relative to the machining means 6 using that position as the origin, and the workpiece can be machined. Next, when detecting the position of the chuck table 4 in the Y-axis direction, moiré fringes are first generated on the Y-axis grid chart 58b. At this time, the photomask 60 is positioned in the second position so that the transparent portion 68 and the shielding portion 70 of the photomask 60 are arranged alternately in the Y-axis direction. Then, light is irradiated from the light source 46 of the illumination means 12. The light irradiated from the light source 46 passes through the photomask 60 and projection lens 62 of the moiré fringe generation mechanism 16 and irradiates the movable range of the chuck table 4. As a result, since the photomask 60 is positioned in the second position, the light that has passed through the projection lens 62 is projected onto the Y-axis grid chart 58b at second equal intervals in the Y-axis direction, and moiré fringes with a larger period than the first and second equal intervals are generated on the Y-axis grid chart 58b.

[0040] After generating moiré patterns on the Y-axis grid chart 58b, the imaging means 14 captures images of the movable range of the chuck table 4, acquiring images of the chuck table 4 and images of the moiré patterns generated on the Y-axis grid chart 58b. When acquiring images of the moiré patterns, the imaging means 14 captures images while the chuck table 4 is moved by the Y-axis feed means 10, acquiring images of multiple moiré patterns.

[0041] After capturing the movable range of the chuck table 4, the first image processing unit 54 roughly detects the position of the chuck table 4 in the Y-axis direction by pattern matching the acquired captured image of the chuck table 4 with a pre-registered image.

[0042] After roughly detecting the Y-axis position of the chuck table 4, the second image processing unit 56 detects the Y-axis position of the chuck table 4 with high precision. In this process, first, multiple images of moiré fringes are processed to determine the relationship between the light intensity of the moiré fringes and the Y-axis position. Next, based on the relationship between the light intensity of the moiré fringes and the Y-axis position, the relationship between the amount of movement of the chuck table 4 and the position of the moiré fringes is determined. Then, the second image processing unit 56 can detect the Y-axis position of the chuck table 4 with high precision based on the relationship between the amount of movement of the chuck table 4 and the position of the moiré fringes.

[0043] As described above, in this embodiment, regardless of the position of the chuck table 4 within its movable range, the illumination means 12 can illuminate the chuck table 4 and the imaging means 14 can image the chuck table 4. Therefore, when the moiré pattern generation mechanism 16 generates moiré patterns and the imaging means 14 images the moiré patterns to detect the position of the chuck table 4, there is no need to adjust the position of the chuck table 4. Accordingly, with the processing apparatus 2 of this embodiment, there is no need to return the chuck table 4 to the sensor end each time initial settings are performed, thus preventing a decrease in productivity.

[0044] Furthermore, in this embodiment, the imaging means 14 captures images of the movable range of the chuck table 4, which is a relatively wide area. However, by capturing images of moiré patterns that move at an amount approximately 100 times the amount of movement of the chuck table 4 with the imaging means 14, the position of the chuck table 4 can be detected with high accuracy. [Explanation of Symbols]

[0045] 2: Processing equipment 4: Chuck Table 6: Processing means 8: X-axis feed mechanism 10: Y-axis feed mechanism 12: Lighting means 14: Imaging means 16: Moire pattern generation mechanism 54: First Image Processing Unit 56: Second Image Processing Unit 58: Grid Chart 58a: X-axis grid chart 58b: Y-axis grid chart 60: Photomask 62: Projection lens 64:Reflector 66: Non-reflective part 68:Transparent part 70: Shield part 72: Light projected onto a grid chart 72a: bright line 72b: Dark line

Claims

1. A processing apparatus comprising at least a chuck table for holding a workpiece, and processing means for processing the workpiece held on the chuck table, The system comprises an X-axis feed means for machining feed of the chuck table in the X-axis direction, an illumination means for irradiating light into the movable range of the chuck table, an imaging means for acquiring an image within the movable range of the chuck table, and a moiré fringe generation mechanism. The moiré pattern generation mechanism is, A grid chart is provided adjacent to the chuck table, in which reflective sections that reflect light and non-reflective sections that absorb light are formed alternately at first equal intervals, A photomask is provided for the lighting means, having light-transmitting portions and light-blocking portions formed alternately at equal intervals, The system includes a projection lens that projects light that has passed through the photomask onto the grid chart at second equal intervals, A machining apparatus that slightly differs the first equal interval and the second equal interval so as to generate moiré fringes, and detects the position of the chuck table in the X-axis direction by imaging the moiré fringes with the imaging means.

2. When the resolution of the imaging means is W0 (μm), the first equal interval is W1 (μm), the second equal interval is W0 (μm), and W1 (μm) = W0 (μm) + x (μm), When the chuck table is moved by x (μm) using the X-axis feed mechanism, the moiré pattern moves by W0 (μm). The processing apparatus according to claim 1, wherein the resolution of the imaging means is x (μm).

3. The imaging means comprises a first image processing unit and a second image processing unit. The first image processing unit detects the position of the chuck table in the X-axis direction with a resolution of W0 (μm) by pattern matching between a pre-registered registered image and an captured image. The processing apparatus according to claim 2, wherein the second image processing unit detects the position of the chuck table in the X-axis direction with a resolution of x (μm) by the movement of the moiré fringes.

4. The system further includes a Y-axis feed mechanism for machining the chuck table in the Y-axis direction, which is perpendicular to the X-axis direction. The processing apparatus according to claim 1, wherein moiré patterns are imaged by the imaging means and the position of the chuck table in the Y-axis direction is detected.

Images