JP2018032825A - Alignment method for work piece - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an alignment method for a work piece capable of surely detecting a direction of the work piece.SOLUTION: The present invention relates to an alignment method for a work piece including: a carry-in step for carrying a work piece on which a mark indicating a direction is provided, into a chuck table; a search step for imaging the work piece with an imaging unit while rotating the chuck table in a first direction within a range of a predetermined angle after the carry-in step is implemented, and searching for the mark; a replacement step for carrying the work piece out of the chuck table with a carriage unit in a case where the mark cannot be detected in the search step, retracting the work piece, rotating the chuck table in a second direction that is opposite to the first direction, and thereafter carrying the work piece into the chuck table again; and a direction adjustment step for rotating the chuck table based on the mark that is detected in the search step, and matching the direction of the work piece with a predetermined direction. The search step and the replacement step are repeated until the mark can be detected.SELECTED DRAWING: Figure 5

Description

  The present invention relates to a workpiece alignment method applied when processing a plate-like workpiece.

  When processing a plate-shaped workpiece typified by a semiconductor wafer or a package substrate, a processing including a chuck table that holds the workpiece and a processing unit that processes the workpiece held on the chuck table The device is used. Before processing a workpiece with this processing apparatus, it is necessary to perform a process called alignment for causing the processing apparatus to recognize the position, orientation, and the like of the workpiece.

  In the alignment, for example, the workpiece held on the chuck table is imaged by the imaging unit, and a pattern matching the characteristic key pattern (target pattern) stored in advance in the machining apparatus is found from the workpiece. . Next, the orientation of the workpiece (chuck table) is adjusted based on the found pattern, and the actual planned machining line position is determined from the distance between the planned machining line (street) stored in the machining device and the key pattern. Identify.

  By the way, in the above-described alignment, a device such as an electronic circuit periodically arranged on a workpiece is often used as a key pattern. In this case, if the orientation of the workpiece after being loaded into the chuck table is out of the allowable range, another pattern adjacent to the pattern that should be detected can be erroneously detected, and the planned division line can be specified. There is a high possibility of disappearing.

  On the other hand, a detection device, a detection method, and the like that detect the orientation of the workpiece based on the position of a notch, an orientation flat, or the like before carrying the workpiece into the chuck table have been proposed (for example, Patent Document 1). By detecting the orientation of the workpiece in advance and taking the workpiece into the chuck table while taking this orientation into account, it is possible to prevent the pattern from being erroneously detected by matching the orientation of the workpiece to the desired direction.

JP 2005-11917 A

  However, the detection device used in the above-described detection method is expensive and requires a large installation space. Therefore, this detection method cannot be used when there is a great demand for cost reduction and space saving.

  On the other hand, if the orientation of the workpiece can be detected using an imaging unit or the like of the machining apparatus, the orientation of the workpiece can be adjusted to a desired direction without using another detection device as described above. It is done. However, in this case, since the workpiece is imaged by the imaging unit while rotating the chuck table, for example, when the rotation angle of the chuck table is limited, the orientation of the workpiece is always detected. could not.

  The present invention has been made in view of such problems, and an object of the present invention is to provide a workpiece alignment method capable of reliably detecting the orientation of the workpiece even when the rotation angle of the chuck table is limited. Is to provide.

  According to one aspect of the present invention, a chuck table that holds a plate-like workpiece and rotates within a predetermined angle range, a processing unit that processes the workpiece held on the chuck table, and the chuck table Workpiece alignment using a processing apparatus comprising: a transport unit that loads a workpiece into the workpiece and unloads the workpiece from the chuck table; and an imaging unit that images the workpiece held on the chuck table. A loading step of loading a workpiece provided with a mark indicating the direction into the chuck table; and after performing the loading step, the chuck table is moved in the first direction within a range of the predetermined angle. A search step for picking up an image of the workpiece with the image pickup unit while rotating and searching for the mark, and when the mark cannot be detected in the search step, The workpiece is unloaded from the chuck table with a robot and retracted, and the chuck table is rotated in a second direction opposite to the first direction, and then the workpiece is loaded again into the chuck table. A search step until the mark can be detected, comprising: a correction step; and an orientation adjustment step of rotating the chuck table based on the mark detected in the search step to align the direction of the workpiece with a predetermined direction. And a workpiece alignment method that repeats the repositioning step.

  In one embodiment of the present invention, the mark is preferably a notch indicating a crystal orientation formed on the outer periphery of the workpiece.

  The workpiece alignment method according to one aspect of the present invention includes a search step of imaging a workpiece with an imaging unit while rotating the chuck table in the first direction and searching for the mark, and the mark can be detected by the search step. If there is no workpiece, the workpiece is unloaded from the chuck table by the transfer unit, retracted, rotated in the second direction opposite to the first direction, and then loaded into the chuck table again. Since the steps are repeated until the mark can be detected, the orientation of the workpiece can be reliably detected even when the rotation angle of the chuck table is limited.

It is a figure which shows typically the structural example of a processing apparatus. FIG. 2A and FIG. 2B are side views for explaining the carry-in step. FIG. 3A is a plan view for explaining the search step, and FIG. 3B is a side view for explaining the search step. FIG. 4A is a plan view schematically showing a state after the chuck table is rotated in the search step, and FIG. 4B is a plan view in which the workpiece is unloaded from the chuck table in the repositioning step. It is a side view which shows a mode typically. FIG. 5A is a plan view schematically showing how the chuck table is rotated in the second direction opposite to the first direction in the repositioning step, and FIG. It is a side view which shows a mode that a workpiece is carried in to a chuck table. FIG. 6A is a plan view for explaining the second search step, and FIG. 6B is a side view for explaining the second search step. FIG. 7A is a plan view schematically showing how the notch is detected in the second search step, and FIG. 7B is a plan view for explaining the orientation adjustment step.

  Embodiments according to one aspect of the present invention will be described with reference to the accompanying drawings. The workpiece alignment method according to this embodiment includes a carry-in step (see FIGS. 2A and 2B), a search step (FIGS. 3A, 3B, and 4A). 6A, FIG. 6B and FIG. 7A), repositioning step (see FIG. 4B, FIG. 5A and FIG. 5B), and orientation adjustment step (FIG. 7 (B)).

  In the carry-in step, the work piece provided with the mark indicating the direction is carried into the chuck table of the processing apparatus. In the searching step, the workpiece is imaged by the imaging unit of the machining apparatus while the chuck table is rotated in the first direction, and the mark is searched. If the mark is not detected in this search step, a replacement step is performed next.

  In the repositioning step, the workpiece is unloaded from the chuck table by the transfer unit of the machining apparatus, the chuck table is rotated in the second direction opposite to the first direction, and then the workpiece is loaded again into the chuck table. . After the repositioning step, a search step is performed to detect the mark.

  In the orientation adjustment step, the chuck table is rotated based on the mark detected in the search step, and the orientation of the workpiece is adjusted to a predetermined direction. Note that the search step and the rearrangement step are repeated until a mark can be detected. The workpiece alignment method according to this embodiment will be described in detail below.

  FIG. 1 is a perspective view schematically showing a configuration example of a processing apparatus in which the workpiece alignment method according to the present embodiment is used. In the present embodiment, a processing device (cutting device) for cutting a workpiece is illustrated, but the workpiece alignment method according to the present invention is applied to a laser processing device or the like for processing a workpiece with a laser beam. It can also be applied.

  As shown in FIG. 1, the processing apparatus (cutting apparatus) 2 includes a base 4 that supports each structure. A rectangular opening 4a is formed at the front corner of the base 4, and a cassette support base 6 that moves up and down is provided in the opening 4a. On the upper surface of the cassette support 6, a cassette 8 that houses a plurality of workpieces 11 is placed. In FIG. 1, only the outline of the cassette 8 is shown for convenience of explanation.

  The workpiece 11 is, for example, a circular wafer made of a semiconductor material such as silicon, and the surface 11a side is divided into a central device region and an outer peripheral surplus region surrounding the device region. The device area is further divided into a plurality of areas by planned processing lines (streets, planned dividing lines) arranged in a lattice pattern, and devices 13 such as ICs and LSIs are formed in each area.

  A notch (notch) 11 c that is a mark indicating the direction (for example, crystal orientation) of the workpiece 11 is provided on the outer peripheral edge of the workpiece 11. However, instead of the notch 11c, an orientation flat (notch) or the like may be provided as a mark. Further, a protective member such as a dicing tape may be attached to the back surface 11b (see FIG. 2A, etc.) of the workpiece 11.

  In this embodiment, a circular wafer made of a semiconductor material such as silicon is used as the workpiece 11. However, the material, shape, structure, etc. of the workpiece 11 are not limited. For example, a substrate made of a material such as ceramics, resin, or metal can be used as the workpiece 11. There are no restrictions on the type, quantity, and arrangement of devices.

  A rectangular opening 4b that is long in the X-axis direction (front-rear direction, processing feed direction) is formed on the side of the cassette support base 6. In the opening 4b, there are provided an X-axis moving table 10, an X-axis moving mechanism (not shown) for moving the X-axis moving table 10 in the X-axis direction, and a dustproof and splash-proof cover 12 that covers the X-axis moving mechanism. .

  The X-axis movement mechanism includes a pair of X-axis guide rails (not shown) parallel to the X-axis direction, and the X-axis movement table 10 is slidably attached to the X-axis guide rails. A nut portion (not shown) is provided on the lower surface side of the X-axis moving table 10, and an X-axis ball screw (not shown) parallel to the X-axis guide rail is screwed to the nut portion.

  An X-axis pulse motor (not shown) is connected to one end of the X-axis ball screw. By rotating the X-axis ball screw with the X-axis pulse motor, the X-axis moving table 10 moves in the X-axis direction along the X-axis guide rail.

  A chuck table 14 for holding the workpiece 11 is provided above the X-axis moving table 10. The chuck table 14 is connected to a rotation drive source (not shown) such as a motor, and rotates around a rotation axis substantially parallel to the Z-axis direction (vertical direction) within a predetermined angle range (for example, 200 °). To do. Further, the chuck table 14 is moved between the front loading / unloading position and the rear processing position by the above-described X-axis moving mechanism, and is further processed and fed in the vicinity of the processing position.

  The upper surface of the chuck table 14 is a holding surface 14 a that sucks and holds the workpiece 11. The holding surface 14a is connected to a suction source 18 (see FIG. 2A) through a suction path 14b (see FIG. 2A) formed on the chuck table 14 and a valve 16 (see FIG. 2A). )It is connected to the.

  In the vicinity of the opening 4 b and the cassette support 6, a first transport unit 20 is provided that takes out the workpiece 11 from the cassette 8 or accommodates the workpiece 11 into the cassette 8. The first transport unit 20 is connected to a horizontal movement unit (not shown), and can move mainly in the Y-axis direction (left-right direction, index feed direction).

  On the upper surface of the base 4, a gate-type first support structure 22 is disposed so as to straddle the opening 4 b. A first rail 24 that is substantially parallel to the Y-axis direction is provided on the front surface of the first support structure 22, and a second transport unit 28 is attached to the first rail 24 via a first elevating unit 26. It has been.

  The second transport unit 28 moves in the Y-axis direction along the first rail 24, and moves in the Z-axis direction by the first lifting / lowering unit 26. The second transport unit 28 can receive the workpiece 11 from the chuck table 14 or the first transport unit 20, and can deliver the workpiece 11 to the chuck table 14 or the first transport unit 20.

  In other words, the workpiece 11 taken out from the cassette 8 by the first transport unit 20 can be received by the second transport unit 28 and carried into the chuck table 14. Further, the workpiece 11 can be unloaded from the chuck table 14 by the second conveyance unit 28, and the workpiece 11 can be transferred to the first conveyance unit 20.

  A second rail 30 that is substantially parallel to the Y-axis direction is provided above the first rail 24, and a third transport unit 34 is attached to the second rail 30 via a second lifting / lowering unit 32. ing. The third transport unit 34 moves in the Y-axis direction along the second rail 30, and moves in the Z-axis direction by the second lifting / lowering unit 32.

  A gate-shaped second support structure 36 is disposed behind the first support structure 22. Two sets of processing units (cutting units) 40 are provided on the front surface of the second support structure 36 via moving units 38, respectively. The processing unit 40 is moved in the Y-axis direction and the Z-axis direction by the moving unit 38.

  Each processing unit 40 includes a spindle (not shown) serving as a rotation axis substantially parallel to the Y-axis direction. An annular cutting blade 42 is attached to one end of the spindle. A rotation drive source (not shown) such as a motor is connected to the other end side of the spindle, and the cutting blade 42 is rotated by a force transmitted from the rotation drive source.

  At a position adjacent to the processing unit 40, an imaging unit 44 for imaging the workpiece 11 and the like held on the chuck table 14 is provided. The imaging unit 44 is moved in the Y-axis direction and the Z-axis direction together with the processing unit 40 by the moving unit 38.

  When cutting the workpiece 11 with the processing apparatus 2, first, the chuck table 14 in a state where the workpiece 11 is held and the processing unit 40 are moved relatively to each other, and a processing scheduled line to be cut. The cutting blade 42 is aligned with the extended line. Next, the lower end of the cutting blade 42 is lowered to a position lower than the surface 11 a of the workpiece 11.

  Thereafter, the cutting blade 42 and the chuck table 14 that have been rotated are moved relative to each other in a direction parallel to the target processing line, so that the cutting blade 42 is cut into the workpiece 11, and the target The workpiece 11 can be cut along the planned machining line.

  A circular opening 4c is formed at a position opposite to the opening 4a with respect to the opening 4b. A cleaning unit 46 for cleaning the workpiece 11 and the like after cutting is provided in the opening 4c. The workpiece 11 processed by the processing unit 40 is transported to the cleaning unit 46 by the third transport unit 34. The workpiece 11 cleaned by the cleaning unit 46 is transferred to the first transport unit 20 by the second transport unit 28 and stored in the cassette 8.

  X-axis moving mechanism, chuck table 14, first transport unit 20, horizontal movement unit, first lifting unit 26, second transport unit 28, second lifting unit 32, third transport unit 34, moving unit 38, processing unit 40 A control unit 48 is connected to components such as the imaging unit 44 and the cleaning unit 46. Each component is controlled by this control unit 48.

  Next, a workpiece alignment method according to the present embodiment will be described. In the workpiece alignment method according to the present embodiment, first, a carry-in step of carrying the workpiece 11 into the chuck table 14 is performed. FIG. 2A and FIG. 2B are side views for explaining the carry-in step.

  In this carry-in step, first, the workpiece 11 is taken out from the cassette 8 by the first transport unit 20 and transferred to the second transport unit 28. Further, the position of the chuck table 14 is adjusted to the forward loading / unloading position, and the second transport unit 28 is moved directly above the chuck table 14.

  2A, the second transport unit 28 is lowered, and the workpiece 11 is placed on the chuck table 14 so that the back surface 11b side of the workpiece 11 contacts the holding surface 14a. In this state, when the valve 16 is opened as shown in FIG. 2B and the negative pressure of the suction source 18 is applied to the holding surface 14a, the workpiece 11 is sucked and held by the chuck table 14.

  After the carry-in step, a search step for detecting the notch 11c of the workpiece 11 is performed. 3A is a plan view for explaining the search step, FIG. 3B is a side view for explaining the search step, and FIG. 4A is a chuck table in the search step. It is a top view which shows typically the state after rotating 14. 3A and 4A, the mark A for indicating the orientation of the chuck table 14 is also shown, but the mark A is not necessarily attached to the chuck table 14. It is not necessary.

  In the search step, first, the chuck table 14 and the imaging unit 44 are relatively moved, and as shown in FIGS. 3A and 3B, the imaging range 44a of the imaging unit 44 is set in the workpiece 11. Fit to the outer periphery. Thereafter, the outer peripheral edge of the workpiece 11 is imaged by the imaging unit 44 while the chuck table 14 is rotated in the first direction, and an image showing the outer peripheral edge of the workpiece 11 is formed. An image formed by imaging is sent to the control unit 48.

  For example, the control unit 48 performs image processing such as edge detection on the image sent from the imaging unit 44 and finds (detects) the notch 11c. Such search (imaging and image processing) of the notch 11c is repeated until the notch 11c is detected or the rotation angle of the chuck table 14 reaches a predetermined angle as shown in FIG. It is done.

  As shown in FIG. 4A, when the notch 11c does not reach the imaging range 44a until the rotation angle of the chuck table 14 reaches a predetermined angle, the notch 11c cannot be detected. Then, a repositioning step is performed in which the workpiece 11 is repositioned on the chuck table 14. If the notch 11c can be detected in this search step, it is sufficient to proceed to the orientation adjustment step without performing the replacement step.

  FIG. 4B is a side view schematically showing how the workpiece 11 is unloaded from the chuck table 14 in the repositioning step, and FIG. 5A is a side view of the chuck table 14 in the repositioning step. FIG. 5B is a plan view schematically illustrating a state in which the workpiece 11 is rotated in a second direction opposite to the first direction, and FIG. 5B schematically illustrates a state in which the workpiece 11 is carried into the chuck table 14 in a repositioning step. FIG.

  In the repositioning step, first, the valve 16 is closed to block the negative pressure of the suction source 18 against the holding surface 14a. Further, as shown in FIG. 4B, the workpiece 11 is held by the second transport unit 28, and is unloaded from the chuck table 14 and retracted. Note that the second transport unit 28 holds the workpiece 11 so as not to rotate until the workpiece 11 is carried into the chuck table 14 again.

  Thereafter, as shown in FIG. 5A, the chuck table 14 is rotated in the second direction opposite to the first direction. Although the rotation angle in the second direction is arbitrary, for example, it may be set to the maximum angle allowed for the chuck table 14. As a result, the notch 11c can be detected efficiently by reducing the number of repetitions of the search step and the replacement step.

  After the chuck table 14 is rotated in the second direction, as shown in FIG. 5B, the second transport unit 28 is lowered, and the workpiece 11 is chucked so that the back surface 11b side contacts the holding surface 14a. Place it on the table 14. In this state, when the valve 16 is opened as shown in FIG. 5B and the negative pressure of the suction source 18 is applied to the holding surface 14a, the workpiece 11 is sucked and held by the chuck table 14.

  In this repositioning step, the workpiece 11 is held so as not to rotate, the chuck table 14 is rotated in the second direction, and then the workpiece 11 is carried into the chuck table 14 again. The relationship between the direction and the direction of the chuck table 14 changes. Specifically, the chuck table 14 is rotated in the second direction with respect to the workpiece 11.

  After the repositioning step, the search step for detecting the notch 11c of the workpiece 11 is performed again. 6A is a plan view for explaining the second search step, and FIG. 6B is a side view for explaining the second search step. FIG. ) Is a plan view schematically showing how the notch 11c is detected in the second search step.

  As shown in FIGS. 6A and 6B, the second search step is performed in the same procedure as the first search step. That is, the outer peripheral edge of the workpiece 11 is imaged by the imaging unit 44 while the chuck table 14 is rotated in the first direction, and an image showing the outer peripheral edge of the workpiece 11 is formed. The control unit 48 performs image processing such as edge detection on the image sent from the imaging unit 44, and finds (detects) the notch 11c.

  As shown in FIG. 7, when the notch 11c is detected and its position is specified, the second search step ends. If the notch 11c cannot be detected in the second search step, the replacement step and the search step may be repeated.

  After the notch 11c is detected in the search step, the chuck table 14 is rotated based on the position of the notch 11c, and an orientation adjusting step for adjusting the orientation of the workpiece 11 to a predetermined direction is performed. FIG. 7B is a plan view for explaining the orientation adjustment step. As shown in FIG. 7B, here, the orientation of the workpiece 11 is adjusted to a predetermined direction by rotating the chuck table 14 in the first direction. In this way, by adjusting the direction of the workpiece 11 to a predetermined direction, it becomes possible to appropriately detect the subsequent pattern and the like.

  As described above, in the workpiece alignment method according to this embodiment, the workpiece 11 is imaged by the imaging unit 44 while the chuck table 14 is rotated in the first direction, and a search for searching for the notch 11c serving as a mark is performed. When the notch 11c cannot be detected in the step and the search step, the workpiece 11 is unloaded from the chuck table 14 by the second transport unit 28 and retracted, and the chuck table 14 is moved in the second direction opposite to the first direction. The workpiece 11 is re-introduced into the chuck table 14 and is repeated until the notch 11c can be detected. Therefore, even when the rotation angle of the chuck table 14 is limited. The direction of the workpiece 11 can be reliably detected.

  In addition, this invention is not restrict | limited to description of the said embodiment, A various change can be implemented. For example, in the above embodiment, the chuck table 14 is rotated in the first direction in the searching step, and the chuck table 14 is rotated in the second direction in the repositioning step. The second direction may be interchanged.

  Moreover, although the said embodiment demonstrated the alignment method of the to-be-processed object using one set of imaging units 44, the notch 11c used as a mark can also be searched for using the some imaging unit 44 simultaneously. In this case, for example, by arranging the imaging ranges 44a of the two sets of imaging units 44 at positions 180 ° apart, the number of repetitions of the search step and the replacement step is halved, and the notch 11c is efficiently searched. it can.

  In addition, the structure, method, and the like according to the above-described embodiment can be appropriately modified and implemented without departing from the scope of the object of the present invention.

11 Workpiece 11a Front surface 11b Back surface 11c Notch (notch)
13 Device 2 Processing device (Cutting device)
4 Base 4a, 4b, 4c Opening 6 Cassette support base 8 Cassette 10 X-axis moving table 12 Dustproof drip-proof cover 14 Chuck table 14a Holding surface 14b Suction path 16 Valve 18 Suction source 20 First transport unit 22 First support structure 24 First rail 26 First lifting unit 28 Second transport unit 30 Second rail 32 Second lifting unit 34 Third transport unit 36 Second support structure 38 Moving unit 40 Processing unit (cutting unit)
42 Cutting blade 44 Imaging unit 46 Cleaning unit 48 Control unit

Claims (2)

A chuck table that holds a plate-like workpiece and rotates within a predetermined angle range, a processing unit that processes the workpiece held on the chuck table, and a workpiece that is carried into the chuck table, A workpiece alignment method using a processing apparatus comprising: a transport unit that unloads a workpiece from a chuck table; and an imaging unit that images a workpiece held on the chuck table,
A carry-in step of carrying a work piece provided with a mark indicating the direction into the chuck table;
After performing the carrying-in step, a search step for imaging the workpiece with the imaging unit while searching for the mark while rotating the chuck table in the first direction within the range of the predetermined angle;
When the mark is not detected in the search step, the work piece is unloaded from the chuck table by the transport unit and retracted, and the chuck table is rotated in a second direction opposite to the first direction. A repositioning step for bringing the work piece into the chuck table again;
A direction adjustment step of rotating the chuck table based on the mark detected in the search step and aligning the direction of the workpiece with a predetermined direction, and
A method of aligning a workpiece, wherein the search step and the repositioning step are repeated until the mark is detected.   The workpiece alignment method according to claim 1, wherein the mark is a notch indicating a crystal orientation formed on an outer periphery of the workpiece.