JP4697843B2 - Alignment device and processing device - Google Patents

Description

  The present invention relates to an alignment apparatus that detects an area to be processed on a wafer and a processing apparatus including the alignment apparatus.

  A semiconductor wafer formed by dividing circuits such as IC and LSI by grid-like streets is divided into semiconductor chips for each circuit by dicing the streets vertically and horizontally using a cutting blade or laser light. The

  Since dicing is performed along the street, an operation called alignment for detecting the street in advance is performed prior to dicing. This alignment is performed by imaging the surface of the semiconductor wafer and performing pattern matching between the key pattern for alignment formed on the surface and the key pattern stored in the alignment device in advance. It is necessary to quickly detect the key pattern.

  Therefore, after first imaging the surface of the semiconductor wafer at a relatively low magnification and roughly detecting the key pattern, the time required for alignment is obtained by imaging the portion at a relatively high magnification and performing precise pattern matching. Some ideas have been made to shorten it.

Japanese Examined Patent Publication No. 3-27043

  However, after performing imaging at a low magnification, the alignment is performed by switching to imaging at a high magnification, so that there is a problem that it takes a relatively long time.

  Therefore, the problem to be solved by the present invention is to further reduce the time required for alignment in various processes relating to the wafer.

The present invention is an alignment apparatus that detects a region to be processed by imaging a wafer formed by dividing a plurality of circuits by streets, an optical system that acquires an optical image of the wafer, and imaging the optical image First imaging means and second imaging means, image processing means for processing images acquired by the first imaging means and the second imaging means, and display means for displaying the processed image The optical axis of the first imaging means and the optical axis of the second imaging means merge with the optical axis of the optical system, and the first imaging means is more than the second imaging means. performing low magnification imaging acquires low magnification image, said second image pickup means, from said first image pickup means by performing high magnification imaging to acquire a high-magnification image, the image processing means, said Image information of a low-magnification key pattern corresponding to a low-magnification image, and corresponding to the high-magnification image Image information of a high-magnification key pattern having a required positional relationship with the magnification key pattern, a required positional relationship between the low-magnification key pattern and the high-magnification key pattern, and a distance between two detection regions that perform alignment An alignment information storage unit that stores at least a low-magnification pattern matching unit that performs low-magnification pattern matching based on the low-magnification key pattern, and a high-magnification pattern matching unit that performs high-magnification pattern matching based on the high-magnification key pattern; , And when performing alignment in one of the detection regions, the low-magnification pattern matching and the high-magnification pattern matching are continuously performed, and when performing alignment in the other detection region, only with performing high magnification pattern matching, the a low magnification image and the high magnification image It is an Abstract that can be displayed on the display means.

  When the low-magnification key pattern and the high-magnification key pattern are respectively formed in the second detection area at a predetermined distance from the first detection area and the first detection area of the wafer, the predetermined value is determined from the first detection area. Drive means for positioning the optical system in the second detection area spaced apart is provided. In this case, it is desirable to include an adjusting unit that adjusts the direction of the region to be processed based on the coordinate information of the first detection region and the coordinate information of the second detection region.

  Moreover, it is desirable to provide an illuminating device that illuminates a region to be processed, and the optical axis of the illuminating device joins the optical axis of the optical system.

  Furthermore, the present invention provides a chuck table for holding a workpiece, an alignment device for detecting a region to be processed of the workpiece held on the chuck table, and a processing for processing a region to be processed detected by the alignment device. A processing apparatus including at least means is provided, the processing apparatus having the gist that the alignment apparatus is configured as described above. In this processing apparatus, the processing means may be a cutting means provided with a cutting blade, or may be a laser light irradiation means for irradiating laser light.

  In the present invention, the optical axis of the first imaging unit and the optical axis of the second imaging unit merge with the optical axis of the optical system, and the low-magnification image acquired by the first imaging unit and the second imaging unit Since the high-magnification image acquired by the imaging unit can be displayed on the display unit at the same time, both images can be checked by the operator at the same time, the operator's work efficiency can be improved, and the time required for alignment can be shortened. .

  In addition, the image processing means includes an alignment information storage unit that stores at least image information of the low-magnification key pattern, image information of the high-magnification key pattern, and their required positional relationship, and low-magnification pattern matching based on the low-magnification key pattern At least a low-magnification pattern matching unit and a high-magnification pattern matching unit that performs high-magnification pattern matching based on a high-magnification key pattern. Therefore, the processing time required for alignment can be shortened from this point as well.

  Moreover, in the processing apparatus provided with such an alignment apparatus, the time required for processing can be shortened as the alignment time is shortened.

  A cutting apparatus 1 shown in FIG. 1 is a processing apparatus that cuts a workpiece such as a semiconductor wafer, and includes a chuck table 2 that holds the workpiece and a region to be cut of the workpiece held on the chuck table 2. , And a cutting means 4 which is a processing means for cutting the region detected by the alignment apparatus 3. In addition, as a processing means, the laser beam irradiation means which irradiates a laser beam can also be used.

  The chuck table 2 can be moved in the X-axis direction by the cutting feed section 5. The cutting feed portion 5 includes a ball screw 50 and a guide rail 51 arranged in the X-axis direction, a pulse motor 52 connected to one end of the ball screw 50, and an internal nut (not shown) screwed into the ball screw 50 and a lower portion. Includes a base 53 slidably engaged with the guide rail 51, and a rotation drive unit 54 disposed on the base 53 and connected to the lower part of the chuck table 2, and is driven by the pulse motor 52. As the ball screw 50 is rotated, the base 53 is guided by the guide rail 51 and moves in the X-axis direction, whereby the chuck table 2 is also moved in the X-axis direction. The chuck table 2 can be rotated by being driven by the rotation drive unit 54.

  The cutting means 4 has a configuration in which a cutting blade 42 is attached to the tip of a spindle 41 that is rotatably supported by a spindle housing 40, and can be moved in the Z-axis direction by a cutting feed section 6 as a whole. . Further, the spindle housing 40 is fixed with an optical system 30 for acquiring an optical image of the workpiece and an imaging unit 31 for capturing the optical image and acquiring image information, which are also similar to the cutting means 4. The cut feed section 6 can move in the Z-axis direction. The image processing unit 32 is connected to an image processing unit 32 that performs processing on image information. The image processing unit 32 is connected to a display unit 33 that displays a processed image on the screen. The imaging unit 31, the image processing unit 32, and the display unit 33 constitute the alignment device 3.

  The notch feed portion 6 includes a ball screw (not shown) and a guide rail 60 disposed in the Z-axis direction on one surface of the wall portion standing in the Z-axis direction, and a pulse motor 61 connected to one end of the ball screw. An internal nut (not shown) is screwed into the ball screw and a side portion is slidably engaged with the guide rail 60, and is supported as the ball screw rotates by being driven by the pulse motor 61. The part 62 is guided by the guide rail 60 and moves in the Z-axis direction, whereby the cutting means 4 supported by the support part 62 is also moved in the Z-axis direction.

  The alignment device 3, the cutting means 4, and the cutting feed unit 6 can be moved in the Y-axis direction by the indexing feed unit 7 as a whole. The index feed unit 7 includes a ball screw 70 and a guide rail 71 arranged in the Y-axis direction, a pulse motor 72 connected to one end of the ball screw 70, an internal nut (not shown) screwed into the ball screw 70, and a lower portion. A base 73 slidably engaged with the guide rail 71 is provided, and the base 73 is guided by the guide rail 71 and driven in the Y-axis direction as the ball screw 70 is rotated by being driven by the pulse motor 72. As a result, the alignment device 3, the cutting means 4 and the cutting feed portion 6 are moved in the Y-axis direction.

  As shown in FIG. 2, the imaging unit 31 includes a first imaging unit 310 and a second imaging unit 311, and the optical axis 310 a of the first imaging unit 310 and the light of the second imaging unit 311. Both the shafts 311 a merge with the optical axis 30 a of the optical system 30 via the half mirror 34. Further, the optical axis of the illumination device 36 also merges with the optical axis 30 a of the optical system 30 via the half mirror 35. The first imaging unit 310 is configured to be imaged on the CCD at a low magnification, for example, optically 1 × magnification, and the second imaging unit 311 is a high magnification, for example, an optically 10 × magnification. If the number of pixels of the CCD is 640 × 480 and the size of the pixel is 10 μm × 10 μm, the accuracy per pixel of the low magnification CCD is 10 μm × 10 μm, and the high magnification CCD The accuracy per pixel is 1 μm × 1 μm.

  Both the first imaging unit 310 and the second imaging unit 311 are connected to the image processing unit 32. The image processing unit 32 includes an alignment information storage unit 320 in which information necessary for alignment is stored in advance, an actual low-magnification key pattern image acquired by the first imaging unit 310, and an alignment information storage unit 320. The low-magnification pattern matching unit 321 that performs pattern matching with the low-magnification key pattern stored in the image, and the actual high-magnification key pattern image acquired by the second imaging unit 311 and the high-value stored in the alignment information storage unit 320 A high-magnification pattern matching unit 322 that performs pattern matching with the magnification key pattern, and a display processing unit 323 that displays images acquired by the first imaging unit 310 and the second imaging unit 311 on the display unit 33 are provided. .

  As shown in FIG. 3, when dicing a semiconductor wafer W formed by dividing a plurality of circuits C to be chips later by streets S, the semiconductor wafer W has a dicing tape T as shown in FIG. And is held by the chuck table 2 in a state integrated with the dicing frame F. The semiconductor wafer W is positioned immediately below the optical system 30 as the chuck table 2 moves in the + X direction.

  When the semiconductor wafer W is positioned immediately below the optical system 30, the chuck table 2 moves in the X-axis direction or the optical system 30 moves in the Y-axis direction to detect the region to be cut. The imaging unit 310 and the second imaging unit 311 simultaneously capture the surface, and as shown in FIG. 2, two pieces of image information are simultaneously displayed on the display unit 33 by the display processing unit 323 so as to fit on one screen. Then, low-magnification pattern matching is performed, and then high-magnification pattern matching is performed immediately. Therefore, the operator can check both images at the same time, improving work efficiency and reducing the time required for alignment.

  In the display screen example of the display unit 33 in FIG. 2, the image displayed on the right side is the low-magnification image 33 a acquired by the first imaging unit 310, and the image displayed on the left side is the second image. It is the high magnification image 33b acquired by the imaging means 311. The low-magnification image 33a displays a substantially square-shaped low-magnification key pattern 100 and a triangular high-magnification key pattern 101, and the high-magnification image 33b displays the low-magnification key pattern 100. In any image, the alignment reference line 30b formed on the objective lens of the optical system 30 is displayed in the X-axis direction at the center of the image.

  The same image information as the low-magnification key pattern 100 and the high-magnification key pattern 101 necessary for pattern matching is stored in the alignment information storage unit 320 in advance. The alignment information storage unit 320 includes the total number of chips constituting the semiconductor wafer W 2, the chip interval between adjacent chips, the distance from the high magnification key pattern 101 to the center of the street, the low magnification key pattern 100 and the high magnification key. A necessary positional relationship with the pattern 101 is also stored.

  The low-magnification image 33a acquired by imaging by the first imaging unit 310 is transferred to the low-magnification pattern matching unit 321. In the low-magnification pattern matching unit 321, the low-magnification key pattern pixel information stored in advance in the alignment information storage unit 320 and the low-magnification in the low-magnification image 33 a actually acquired by the first imaging unit 310. Pattern matching with the pixel information of the key pattern 100 is performed. In this pattern matching, the cursor 330a on the screen moves and scans the same low-magnification key pattern 100 as the low-magnification key pattern stored in advance, and the low-magnification key pattern 100 that is found first is placed at a predetermined position on the screen. The positioning is performed while the optical system 30 moves in the Y-axis direction and the chuck table 2 moves in the X-axis direction so as to be positioned. When the low-magnification key pattern 100 is positioned at a predetermined position, the high-magnification key pattern 101 is displayed on the screen on the left side of the display means 33 due to the positional relationship between the low-magnification key pattern 100 and the high-magnification key pattern 101. Like that.

  On the other hand, since the imaging by the second imaging unit 311 is performed simultaneously with the imaging by the first imaging unit 310, immediately after the rough alignment based on the low magnification key pattern, the high magnification key pattern is immediately and continuously formed. Can move to precise alignment based.

  The high magnification image 33b acquired by the second imaging unit 311 is transferred to the high magnification pattern matching unit 322. The high magnification pattern matching unit 322 performs pattern matching between the pixel information of the high magnification key pattern stored in advance in the alignment information storage unit 320 and the pixel information of the high magnification key pattern 101 in the high magnification image 33b. .

  The high-magnification key pattern 101 is at a required position in relation to the low-magnification key pattern 100, and since this positional relationship is stored in the alignment information storage unit 320, the high-magnification pattern matching unit 322 has this positional relationship. Based on this, the cursor 330b is moved to perform pattern matching between the pixel information of the key pattern stored in the alignment information storage unit 320 and the pixel information of the high-magnification key pattern 101 included in the acquired high-magnification image 33b. When both key patterns match, it is determined that precise alignment has been achieved.

  Then, when the value of the distance L (see FIG. 4) from the center of the high-magnification key pattern 101 stored in the alignment information storage unit 320 to the center of the street S is read, and the optical system 30 is moved by this distance, As shown in FIG. 4, the center line S1 of the street S matches the alignment reference line 30b.

  However, when the semiconductor wafer W is placed on the chuck table 2, although mechanical alignment is performed by the orientation flat formed on the semiconductor wafer W, an error occurs in the placement state. Therefore, as shown in FIG. 5, alignment is performed at two locations of the first detection region 110 and the second detection region 111 that is separated from the first detection region 111 by a predetermined interval. In this case, the distance between the first detection region 110 and the second detection region 111 is stored in the alignment information storage unit 320 in advance, and after completion of high-magnification pattern matching in the first detection region 110, the optical system 30 or the chuck The table 2 is moved by that distance, and only the high-magnification pattern matching is performed in the second detection area 111. Since the movement of the chuck table 2 is performed by the cutting feed unit 5 shown in FIG. 1, the cutting feed unit 5 serves as a driving means at this time. If necessary, low-magnification pattern matching may be performed similarly to the first detection region 110.

  If the high-magnification key pattern does not match after the chuck table 2 is moved, that is, the high-magnification key pattern in the first detection area 110 and the key pattern in the second detection area 111 do not match in the coordinate information. At this time, it is determined that the semiconductor wafer W is mounted in a shifted state, the angle formed by the line connecting the two locations and the alignment reference line 30b is calculated, and the chuck table 2 is rotated by that angle. The chuck table 2 is rotated by driving the rotation driving unit 54 shown in FIG. 1, and the rotation driving unit 54 serves as an adjustment unit that adjusts the orientation of the semiconductor wafer W.

  As shown in FIG. 6, since the alignment reference line 30b of the optical system 30 and the cutting blade 42 are positioned on a straight line in the X-axis direction, the center line S1 of the street S, which is an area to be cut, is the alignment reference line. When it matches 30b, the cutting position is aligned.

  When the center line S1 of the street S and the cutting blade 42 are aligned in the Y-axis direction in this way, the chuck table 2 is further moved in the + X direction and the cutting means 4 is rotated while the cutting blade 42 rotates at a high speed. Is processed, the street S is cut.

  Further, when the chuck table 2 reciprocates and the cutting blade 42 that rotates at high speed while indexing and feeding the cutting means 4 in the Y-axis direction by the street interval is cut, all streets in the same direction are cut. When the same cutting is performed after the chuck table 2 is rotated 90 degrees, all the streets are cut vertically and horizontally to form individual chips. The alignment described above is also performed on the orthogonal streets.

  In the present invention, a low-magnification image and a high-magnification image are displayed at the same time, and pattern matching at a low magnification and pattern matching at a high magnification can be performed continuously. Therefore, various processes that require efficient alignment are required. Can be used.

It is a perspective view which shows the cutting device which is an example of the processing apparatus of this invention. It is explanatory drawing which shows an example of a structure of the alignment apparatus of this invention. It is a perspective view which shows an example of a semiconductor wafer. It is explanatory drawing which shows an example of the display screen of an alignment apparatus. It is a perspective view which shows the 1st detection area | region and 2nd detection area | region of a semiconductor wafer. It is explanatory drawing which shows the relationship between an optical system and a cutting blade.

1: Cutting device 2: Chuck table 3: Alignment device 30: Optical system 30a: Optical axis 30b: Alignment reference line 31: Imaging unit 310: First imaging unit 311: Second imaging unit 32: Image processing unit 320: Alignment information storage unit 321: Low magnification pattern matching unit 322: High magnification pattern matching unit 323: Display processing unit 33: Display means 33a: Low magnification image 33b: High magnification image 330a, 330b: Cursor 34, 35: Half mirror 36: Illuminating equipment 4: Cutting means 40: Spindle housing 41: Spindle 42: Cutting blade 5: Cutting feed part 50: Ball screw 51: Guide rail 52: Pulse motor 53: Base 54: Rotation drive part 6: Cutting feed part 60: Guide Rail 61: Pulse motor 62: Support part 7: Split Feeding portion 70: Ball screw 71: Guide rail 72: Pulse motor 73: Base W: Semiconductor wafer S: Street S1: Center line 100: Low magnification key pattern 101: High magnification key pattern 110: First detection area 111: Second detection area F: dicing frame T: dicing tape

Claims (6)

An alignment apparatus for detecting a region to be processed by imaging a wafer formed by dividing a plurality of circuits by streets,
An optical system for acquiring an optical image of a wafer, a first imaging unit and a second imaging unit for capturing the optical image, and processing the images acquired by the first imaging unit and the second imaging unit Image processing means to be applied and display means for displaying the processed image, and the optical axis of the first imaging means and the optical axis of the second imaging means merge with the optical axis of the optical system. The first imaging unit captures a low-magnification image by performing low-magnification imaging from the second imaging unit, and the second imaging unit performs higher-magnification imaging than the first imaging unit. Go to get a high magnification image,
The image processing means includes image information of a low magnification key pattern corresponding to the low magnification image, image information of a high magnification key pattern corresponding to the high magnification image and having a required positional relationship with the low magnification key pattern, An alignment information storage unit for storing at least a required positional relationship between the low-magnification key pattern and the high-magnification key pattern and a distance between two detection areas for performing alignment ;
A low-magnification pattern matching unit that performs low-magnification pattern matching based on the low-magnification key pattern;
A high-magnification pattern matching unit that performs high-magnification pattern matching based on the high-magnification key pattern,
When performing alignment in one of the detection regions, the low-magnification pattern matching and the high-magnification pattern matching are continuously performed. When performing alignment in the other detection region, only the high-magnification pattern matching is performed. while performing the alignment device capable of displaying simultaneously said display means and said low magnification image and the high magnification image.   The low-magnification key pattern and the high-magnification key pattern are respectively formed in a first detection area of the wafer and a second detection area that is separated from the first detection area by a predetermined distance. The alignment apparatus according to claim 1, further comprising: a driving unit that positions the optical system in the second detection region that is separated from the region by the predetermined interval.   The alignment apparatus according to claim 2, further comprising an adjusting unit that adjusts an orientation of the region to be processed based on the coordinate information of the first detection region and the coordinate information of the second detection region.   4. The alignment apparatus according to claim 1, further comprising an illumination device that illuminates the region to be processed, wherein the optical axis of the illumination device joins the optical axis of the optical system.   A chuck table for holding a workpiece, an alignment device for detecting a region to be processed of the workpiece held on the chuck table, and a processing means for processing the region to be processed detected by the alignment device; A processing apparatus comprising at least the alignment apparatus, wherein the alignment apparatus is the alignment apparatus according to claim 1.   The processing apparatus according to claim 5, wherein the processing means is a cutting means provided with a cutting blade or a laser light irradiation means for irradiating laser light.

Images