JP2012023256A - Detection method of division plan line - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a detection method of division plan lines capable of efficiently detecting appropriate division plan lines.SOLUTION: A detection method of division plan lines in a processing device includes a first positioning process to take images of two areas distant by a relatively small distance in an X-axis direction of a wafer held onto a chuck table with an imaging camera, detect key patterns for the respective areas, and rotate the chuck table to make correction so that a linear line connecting the detected two key patterns becomes parallel to the X-axis direction; and a second positioning process to take images of two areas distant by a relatively large distance in the X-axis direction of the wafer held onto the chuck table with an imaging camera after the first positioning process, detect key patterns for the respective areas, and rotate the chuck table to make correction so that a linear line connecting the detected two key patterns becomes parallel to the X-axis direction.

Description

  The present invention relates to a method for detecting divisional lines formed in a lattice pattern on a wafer.

  A wafer formed by dividing a plurality of devices such as IC and LSI on the surface by dividing lines is divided into individual devices by dividing the dividing lines by a processing device such as a dicing machine. These devices are used in electric devices such as mobile phones and personal computers.

  A processing apparatus such as a dicing apparatus holds a wafer having a wafer formed with devices formed in each area divided by the planned division lines and a rotatable chuck table, and images the wafer held on the chuck table with a camera, and generates the divided division lines. Detection means for detecting a key pattern to be specified, processing means for performing predetermined processing on the scheduled division line specified by the key pattern detected by the detection means, and processing for processing and feeding the chuck table relatively in the X-axis direction At least a feed means and an index feed means for indexing and feeding the processing means in the Y-axis direction are provided, and the wafer is divided into individual devices by accurately positioning the processing means such as a cutting blade on the division line. .

  In the conventional method for detecting the division line, the detection unit camera picks up two areas separated in the X-axis direction or the Y-axis direction, detects the key pattern existing for each device, and detects the detected two keys. The line to be divided is specified by the pattern. For example, when the chip size (device size) is as small as 1 mm or less, it exists along the adjacent line to be divided instead of the key pattern that exists along the same line to be divided. In some cases, a key pattern to be detected is detected, and if division processing is performed by specifying a line to be divided by such detection, there is a problem in that the device is broken across the actual line to be divided.

  In order to solve this problem, in order to confirm whether or not the planned division line specified by the two detected key patterns is appropriate, the two detected lines are located along the specified divided division line. An alignment method for confirming whether or not another key pattern exists at a position along a straight line connecting the key patterns is proposed by the present applicant and is put into practical use (see Japanese Patent No. 2617870).

Japanese Patent No. 2617870

  However, if there is no other key pattern along the specified division line, there is a problem that the operator has to correct the deviation while looking at the screen, resulting in poor production efficiency.

  The present invention has been made in view of these points, and an object of the present invention is to provide a method of detecting a planned division line that can efficiently detect an appropriate division line.

  According to the first aspect of the present invention, a chuck table that holds and rotates a wafer in which devices are formed in each region divided by the planned division lines, and the wafer held on the chuck table is imaged and divided by an imaging camera. A detecting means for detecting a key pattern for specifying a planned line; a processing means for performing predetermined processing on the planned divided line specified by the key pattern detected by the detecting means; and the chuck table relative to the X-axis direction. A method of detecting a division line in a processing apparatus comprising: a processing feed means for processing and feeding; and an index feed means for relatively indexing and feeding the processing means in the Y-axis direction orthogonal to the X-axis direction, Two areas that are relatively small apart in the X-axis direction of the wafer held on the chuck table are imaged with an imaging camera. A first alignment step of detecting each of the key patterns and correcting the rotation by rotating the chuck table so that a straight line connecting the two detected key patterns is parallel to the X-axis direction; and After performing the aligning process, two regions that are relatively far apart in the X-axis direction of the wafer held on the chuck table are imaged with an imaging camera to detect key patterns, and the two detected key patterns are detected. And a second alignment step of correcting the rotation by rotating the chuck table so that the straight line to be connected is parallel to the X-axis direction.

  According to the second aspect of the present invention, a chuck table that holds and rotates a wafer in which devices are formed in each region divided by the planned division lines, and the wafer held on the chuck table is imaged and divided by an imaging camera. A detecting means for detecting a key pattern for specifying a planned line; a processing means for performing predetermined processing on the planned divided line specified by the key pattern detected by the detecting means; and the chuck table relative to the X-axis direction. A method of detecting a division line in a processing apparatus comprising: a processing feed means for processing and feeding; and an index feed means for relatively indexing and feeding the processing means in the Y-axis direction orthogonal to the X-axis direction, Two areas that are relatively small apart in the Y-axis direction of the wafer held on the chuck table are imaged with an imaging camera. A first alignment step of detecting each key pattern and correcting the rotation by rotating the chuck table so that a straight line connecting the two detected key patterns is parallel to the Y-axis direction; and the first position After performing the aligning process, two regions that are relatively far apart in the Y-axis direction of the wafer held on the chuck table are imaged with an imaging camera to detect key patterns, and the two detected key patterns are detected. And a second alignment step of correcting the rotation by rotating the chuck table so that the connecting straight line is parallel to the Y-axis direction.

  According to the present invention, since the two key patterns are relatively close in the first alignment step, the two key keys are not erroneously detected along the adjacent divided lines. A straight line connecting the patterns can be positioned substantially parallel to the X-axis direction.

  In the second alignment step, since the division line is positioned substantially parallel to the X-axis direction, the keys that exist along the adjacent division line even if the two key patterns are relatively far apart. Without detecting the pattern, the straight line connecting the two key patterns can be positioned in parallel with the X-axis direction with high accuracy.

  Therefore, the conventional problem that the operator has to detect the key pattern existing in the intermediate portion by correcting the deviation while looking at the screen is solved.

It is a schematic perspective view of a cutting device. It is a perspective view of the semiconductor wafer supported by the annular frame via the dicing tape. It is a perspective view which shows a 1st imaging process. It is a schematic diagram explaining a 1st position alignment process. It is a perspective view which shows a 2nd imaging process. It is a schematic diagram explaining a 2nd alignment process.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 shows an external view of a cutting device (dicing device) 2 that can divide a wafer into individual chips (devices).

  On the front side of the cutting device 2, there is provided operating means 4 for an operator to input instructions to the device such as machining conditions. In the upper part of the apparatus, there is provided a display means 6 such as a CRT for displaying a guidance screen for an operator and an image taken by an imaging means described later.

  As shown in FIG. 2, on the surface of the wafer W to be diced, the first street S1 and the second street S2 are formed orthogonally, and the first street S1 and the second street S2 A large number of devices D are formed on the wafer W. Each device D has a key pattern 11 to be detected during alignment.

  The wafer W is attached to a dicing tape T that is an adhesive tape, and the outer peripheral edge of the dicing tape T is attached to an annular frame F. As a result, the wafer W is supported by the frame F via the dicing tape T, and a plurality of wafers (for example, 25 sheets) are accommodated in the wafer cassette 8 shown in FIG. The wafer cassette 8 is placed on a cassette elevator 9 that can move up and down.

  Behind the wafer cassette 8, a loading / unloading means 10 for unloading the wafer W before cutting from the wafer cassette 8 and loading the wafer after cutting into the wafer cassette 8 is disposed. Between the wafer cassette 8 and the loading / unloading means 10, a temporary placement area 12, which is an area on which a wafer to be carried in / out, is temporarily placed, is provided. Positioning means 14 for positioning at a certain position is provided.

  In the vicinity of the temporary placement area 12, transport means 16 having a turning arm that sucks and transports the frame F integrated with the wafer W is disposed, and the wafer W carried to the temporary placement area 12 is Adsorbed by the conveying means 16 and conveyed onto the chuck table 18 and sucked by the chuck table 18, and held on the chuck table 18 by fixing the frame F by a plurality of fixing means (clamps) 19. .

  The chuck table 18 is configured to be rotatable and reciprocally movable in the X-axis direction. Above the movement path of the chuck table 18 in the X-axis direction, alignment means (detection) for detecting the street of the wafer W to be cut. Means) 20 is provided.

  The alignment unit 20 includes an imaging unit (imaging camera) 22 that images the surface of the wafer W, and can detect a street to be cut by processing such as pattern matching based on an image acquired by imaging. The image acquired by the imaging unit 22 is displayed on the display unit 6.

  On the left side of the alignment means 20, a cutting means 24 for cutting the wafer W held on the chuck table 18 is disposed. The cutting means 24 is configured integrally with the alignment means 20, and both move together in the Y-axis direction and the Z-axis direction.

  The cutting means 24 is configured by attaching a cutting blade 28 to the tip of a rotatable spindle 26 and is movable in the Y-axis direction and the Z-axis direction. The cutting blade 28 is located on the extended line of the imaging means 22 in the X-axis direction.

  Next, with reference to FIGS. 3 to 6, a method for detecting a division line according to the embodiment of the present invention will be described in detail. First, as an alignment preparation step, the operator of the cutting device 2 operates the operation means 4 to pick up an image of the wafer W with the image pickup camera 22, and slowly moves the image displayed on the display means 6. The key pattern 11 that is the target of matching is searched. The key pattern 11 uses, for example, a characteristic part of a circuit in the device D. One key pattern 11 is included in each device D.

  When the operator determines the key pattern 11, an image including the key pattern 11 is stored in the memory of the controller of the cutting apparatus 2. Further, the distance between the key pattern 11 and the center line of the streets S1 and S2 is obtained by a coordinate value or the like, and the value is also stored in the memory.

  When cutting along the streets S 1 and S 2 of the wafer W, the alignment unit (detection unit) 20 performs pattern matching between the stored image of the key pattern 11 and the image actually acquired by the imaging camera 22. Do it. Hereinafter, a method for detecting a division planned line according to the embodiment of the present invention will be described in detail.

  First, as shown in FIG. 3, the chuck table 18 is moved in the X-axis direction, and two relatively close areas A and B in the X-axis direction of the wafer W held on the chuck table 18 are imaged by the imaging camera 22. To do.

Then, as shown in FIG. 4, this captured image is displayed on the display means 6 as an image A and an image B. In the image A, the key pattern 11 is detected and set as point A, and the coordinates of point A are set to (x ₁ , y ₁ ). Similarly, in the image B, the key pattern 11 is detected and set as the point B, and the coordinates of the point B are (x ₂ , y ₂ ).

Then, a first alignment process is performed in which the chuck table 18 is rotated and corrected so that the straight line connecting the two imaged key patterns A and B is parallel to the X-axis direction. If the rotation angle of the chuck table 18 in the first alignment step is θ, tan θ = (y ₂ −y ₁ / x ₂ −x ₁ ).

  That is, by rotating the chuck table 18 by θ, the straight line connecting the key patterns A and B can be positioned substantially parallel to the X-axis direction. This rotation angle θ is stored in the memory of the controller.

  After performing the first alignment step, as shown in FIG. 5, the chuck table 18 is moved in the X-axis direction, and the wafer W held on the chuck table 18 is relatively far away in the X-axis direction. Two areas C and D are imaged by the imaging camera 22.

Then, as shown in FIG. 6, the captured images C and D are displayed on the display means 6, the key pattern 11 in the image C is detected and set as the C point, and the coordinates of the C point are (x ₃ , y ₃ ) and To do. Similarly, the key pattern 11 in the image D is detected and set as a D point, and the coordinates of the D point are set to (x ₄ , y ₄ ).

  When the point C and the point D are detected in this way, the chuck table 18 rotates so that the detected straight line connecting the two key patterns 11, that is, the straight line connecting the point C and the point D is parallel to the X-axis direction. Then, a second alignment step for correction is performed.

Here, when the rotation angle of the chuck table 18 in the second alignment step is β, tan β = (y ₄ −y ₃ / x ₄ −x ₃ ).

  That is, in the second alignment step, by rotating the chuck table 18 by β, the straight line connecting the two key patterns 11 can be positioned with high accuracy so as to be parallel to the X-axis direction. This rotation angle β is also stored in the memory of the controller.

  Since the distance between the key pattern 11 and the center line of the street S1 is registered in the controller in advance, the cutting means 24 is moved in the Y-axis direction by the distance between the key pattern 11 and the center line of the street S1 to cut. Alignment, that is, alignment between the street S1 and the cutting blade 28 can be performed.

  When the alignment for the first street S1 extending in the first direction is completed, the chuck table 18 is rotated 90 degrees, and the alignment for the second street S2 extending in the second direction is performed.

  Similarly to the alignment for the first street S1, the alignment for the second street S2 may be composed of the first alignment step and the second alignment step described above. Since S1 is positioned parallel to the X-axis direction, the first alignment step is omitted because the second street S2 after the chuck table 18 is rotated 90 degrees is substantially parallel to the X-axis direction. May be.

  According to the above-described embodiment, since the two key patterns 11 are relatively close in the first alignment step, the key pattern 11 existing along the adjacent division planned line S1 is not erroneously detected. A straight line connecting the two key patterns 11 can be positioned substantially parallel to the X-axis direction.

  In the second alignment step, the planned division line S1 is positioned substantially parallel to the X-axis direction, so that the two key patterns 11 are adjacent to each other even if they are relatively far apart in the X-axis direction. The key pattern 11 existing along the planned division line S1 is not detected by mistake, and the straight line connecting the two key patterns 11 can be positioned in parallel with the X-axis direction with high accuracy.

  Therefore, as in the conventional method of detecting the planned division line, the operator has to check whether the key pattern 11 exists at the position along the predetermined division line S1 by correcting the deviation while looking at the screen. Can be omitted.

  In the above-described embodiment, the imaging camera 22 is stationary and the alignment is performed by moving the chuck table 18 in the X-axis direction. However, the chuck table 18 is stationary and the imaging camera 22 is moved in the Y-axis direction. You may make it implement alignment by moving.

  In this case, in the first alignment step, two regions that are relatively small apart in the Y-axis direction of the wafer held on the chuck table are imaged by the imaging camera, and the key pattern is detected and detected 2 The chuck table is rotated and corrected so that the straight line connecting the individual key patterns is parallel to the Y-axis direction.

  After performing the first alignment step, in the second alignment step, two regions that are relatively far apart in the Y-axis direction of the wafer held by the chuck table are imaged with an imaging camera, and key patterns are respectively obtained. Then, the chuck table is rotated and corrected so that the straight line connecting the two detected key patterns is parallel to the Y-axis direction.

W Semiconductor wafers S1, S2 Divided line D Device T Dicing tape F Annular frame 2 Cutting device 6 Display means 11 Key pattern 18 Chuck table 22 Imaging means (imaging camera)
24 Cutting means 28 Cutting blade

Claims (2)

A chuck table that holds and rotates a wafer in which devices are formed in each area divided by the planned division lines, and detects a key pattern that identifies the planned division lines by imaging the wafer held on the chuck table with an imaging camera. Detecting means for processing, processing means for performing predetermined processing on the scheduled division line specified by the key pattern detected by the detecting means, processing feed means for processing and feeding the chuck table relatively in the X-axis direction, A method for detecting a division line in a processing apparatus comprising: an index feeding means for indexing and feeding the machining means relative to the Y-axis direction orthogonal to the X-axis direction,
Two regions that are relatively small apart in the X-axis direction of the wafer held on the chuck table are imaged with an imaging camera to detect each key pattern, and a straight line connecting the two detected key patterns is the X-axis direction. A first alignment step of correcting by rotating the chuck table so as to be parallel;
After performing the first alignment step, two regions that are relatively far apart in the X-axis direction of the wafer held on the chuck table are imaged with an imaging camera, and a key pattern is detected, respectively. A second alignment step of correcting by rotating the chuck table so that a straight line connecting the key patterns is parallel to the X-axis direction;
A method of detecting a division line to be divided. A chuck table that holds and rotates a wafer in which devices are formed in each area divided by the planned division lines, and detects a key pattern that identifies the planned division lines by imaging the wafer held on the chuck table with an imaging camera. Detecting means for processing, processing means for performing predetermined processing on the scheduled division line specified by the key pattern detected by the detecting means, processing feed means for processing and feeding the chuck table relatively in the X-axis direction, A method for detecting a division line in a processing apparatus comprising: an index feeding means for indexing and feeding the machining means relative to the Y-axis direction orthogonal to the X-axis direction,
Two regions that are relatively small apart in the Y-axis direction of the wafer held by the chuck table are imaged by an imaging camera to detect a key pattern, and the straight line connecting the two detected key patterns is the Y-axis direction. A first alignment step of correcting by rotating the chuck table so as to be parallel;
After performing the first alignment step, two regions that are relatively far apart in the Y-axis direction of the wafer held on the chuck table are imaged with an imaging camera, and a key pattern is detected, respectively. A second alignment step of correcting by rotating the chuck table so that a straight line connecting the key patterns is parallel to the Y-axis direction;
A method of detecting a division line to be divided.

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