JP5976331B2 - Grinding equipment - Google Patents

Description

  The present invention relates to a grinding apparatus for grinding a wafer such as a semiconductor wafer, and more particularly to a grinding apparatus capable of grinding a plurality of types of wafers under appropriate processing conditions.

  As is well known to those skilled in the art, in a semiconductor device manufacturing process, a semiconductor wafer on which a plurality of devices such as ICs and LSIs are formed is ground by a grinding device on a back surface before being divided into individual chips. It is formed in the thickness. A grinding apparatus for grinding the back surface of a semiconductor wafer includes a chuck table for sucking and holding a wafer, a grinding means for grinding the wafer sucked and held on the chuck table, and a wafer before processing from a cassette containing the wafer before grinding. A conveying means for taking out the processed wafer and storing the processed wafer in a cassette, a temporary placing means for temporarily placing the wafer conveyed by the conveying means, and a loading operation for bringing the wafer centered by the temporary placing means into the chuck table. Means. (For example, see Patent Document 1)

JP 2002-319559 A

  Thus, when a plurality of different types of wafers are accommodated in the cassette, the rotation speed of the chuck table, the rotation speed of the grinding wheel constituting the grinding means, and the grinding feed speed of the grinding means according to the type of wafer It is necessary to change the processing conditions. In this way, in order to change the processing conditions according to the type of wafer, the order is set for the types of wafers contained in the cassette, and the processing conditions are automatically changed according to the set order. However, if the order is wrong, the processing conditions do not match, so that grinding is performed under processing conditions that do not correspond to the type of wafer, and there is a problem that a great deal of damage is caused.

  The present invention has been made in view of the above facts, and the main technical problem thereof is a grinding apparatus capable of grinding under appropriate processing conditions corresponding to the type of wafer when grinding a plurality of different types of wafers. Is to provide.

In order to solve the above main technical problem, according to the present invention, a grinding table having a chuck table having a holding surface for sucking and holding a wafer and a grinding wheel for grinding the wafer sucked and held by the holding surface of the chuck table. And a grinding feed means for grinding and feeding the grinding means in a grinding feed direction perpendicular to the holding surface of the chuck table, and a carry-in means for carrying the wafer before grinding to the holding surface of the chuck table. In grinding equipment,
Detection means for detecting a pre-grinding wafer that is carried into the chuck table by the carry-in means, control for determining the type of wafer detected by the detection means, and selecting processing conditions corresponding to the determined wafer type has been and means, the,
The detection means comprises imaging means for imaging a device formed on the wafer surface and outputting an image signal to the control means,
The control means performs pattern matching based on an image signal of a key pattern set as a characteristic part of a device formed on the surface of the wafer, and determines the type of the wafer.
A grinding device is provided.

The control means includes a feature part determination map for determining a wafer type set based on the key pattern, and a memory for storing a processing condition map in which a processing condition corresponding to the wafer type is set. The wafer type is determined by comparing the image signal with the device feature set in the feature determination map, and a processing condition corresponding to the determined wafer type is selected from the processing condition map.
Temporary placing means for temporarily placing a wafer before grinding before being carried into the chuck table by the carry-in means is provided, and the detecting means detects the wafer temporarily placed on the temporary placing means.

  In the grinding apparatus according to the present invention, the detecting means for detecting the pre-grinding wafer that is carried into the chuck table by the carrying-in means, the type of the wafer detected by the detecting means is determined, and the processing conditions corresponding to the determined wafer type Therefore, even when grinding a plurality of different types of wafers, roughing is performed under proper processing conditions corresponding to the types of wafers to be ground and held by the chuck table. It can be ground.

1 is a perspective view of a grinding apparatus constructed according to the present invention. The perspective view which shows other embodiment of the imaging means as a detection means with which the grinding apparatus shown in FIG. 1 is equipped. The block block diagram of the control means with which the grinding apparatus shown in FIG. 1 is equipped. The perspective view of the semiconductor wafer as a wafer which is a workpiece. Explanatory drawing which shows the protective tape sticking process of sticking a protective tape on the surface of the semiconductor wafer shown in FIG. Explanatory drawing of the characteristic part determination map stored in the memory of the control means with which the grinding apparatus shown in FIG. 1 is equipped. Explanatory drawing of the process condition map stored in the memory of the control means with which the grinding apparatus shown in FIG. 1 is equipped.

  Preferred embodiments of a grinding apparatus constructed according to the present invention will be described below in more detail with reference to the accompanying drawings.

FIG. 1 shows a perspective view of a grinding apparatus constructed in accordance with the present invention.
The grinding device in the illustrated embodiment includes a device housing 2 having a substantially rectangular parallelepiped shape. A stationary support plate 21 is erected on the upper right end of the device housing 2 in FIG. Two pairs of guide rails 22, 22 and 23, 23 extending in the vertical direction are provided on the inner surface of the stationary support plate 21. A rough grinding unit 3 as rough grinding means is mounted on one guide rail 22, 22 so as to be movable in the vertical direction, and a finish grinding unit 4 as finish grinding means is vertically mounted on the other guide rail 23, 23. It is mounted to move in the direction.

  The rough grinding unit 3 includes a unit housing 31, a rough grinding wheel 33 attached to a wheel mount 32 rotatably attached to the lower end of the unit housing 31, and a wheel mount 32 attached to the upper end of the unit housing 31. A servo motor 34 that rotates in a direction indicated by an arrow 32a and a moving base 35 on which the unit housing 31 is mounted are provided.

  The movable base 35 is provided with guided rails 351 and 351, and the guided rails 351 and 351 are movably fitted to the guide rails 22 and 22 provided on the stationary support plate 21. The rough grinding unit 3 is supported so as to be movable in the vertical direction. The rough grinding unit 3 in the illustrated form includes a grinding feed means 36 for moving the moving base 35 along the guide rails 22 and 22 and grinding and feeding the rough grinding wheel 33. The grinding feed means 36 includes a male screw rod 361 that is disposed on the stationary support plate 21 in parallel with the guide rails 22 and 22 and is rotatably supported, and a pulse motor 362 for rotationally driving the male screw rod 361. And a female screw block (not shown) that is mounted on the moving base 35 and is screwed with the male screw rod 361. By driving the male screw rod 361 forward and backward by a pulse motor 362, the rough grinding unit 3 is moved up and down. It is moved in the direction (direction perpendicular to the holding surface of the chuck table described later).

  The finish grinding unit 4 is also configured in the same manner as the rough grinding unit 3, and includes a unit housing 41, a finish grinding wheel 43 attached to a wheel mount 42 rotatably attached to the lower end of the unit housing 41, A servo motor 44 that is mounted on the upper end of the unit housing 41 and rotates the wheel mount 42 in the direction indicated by the arrow 42a, and a moving base 45 on which the unit housing 41 is mounted are provided.

  Guided rails 451 and 451 are provided on the moving base 45, and the guided rails 451 and 451 are movably fitted to the guide rails 23 and 23 provided on the stationary support plate 21. The finish grinding unit 4 is supported so as to be movable in the vertical direction. The finish grinding unit 4 in the form shown in the figure includes grinding feed means 46 for moving the moving base 45 along the guide rails 23 and 23 and grinding and feeding the finish grinding wheel 43. The grinding feed means 46 includes a male screw rod 461 that is disposed on the stationary support plate 21 in the vertical direction in parallel with the guide rails 23 and 23 and is rotatably supported, and a pulse motor 462 for rotationally driving the male screw rod 461. And a female screw block (not shown) that is mounted on the moving base 45 and is screwed with the male screw rod 461. By driving the male screw rod 461 forward and backward by a pulse motor 462, the finish grinding unit 4 is moved up and down. It is moved in the direction (direction perpendicular to the holding surface of the chuck table described later).

  The grinding apparatus in the illustrated embodiment includes a turntable 5 disposed so as to be substantially flush with the upper surface of the apparatus housing 2 on the front side of the stationary support plate 21. The turntable 5 is formed in a relatively large-diameter disk shape, and is appropriately rotated in a direction indicated by an arrow 5a by a rotation driving mechanism (not shown). In the illustrated embodiment, three chuck tables 6 are arranged on the turntable 5 so as to be rotatable in a horizontal plane with a phase angle of 120 degrees. The chuck table 6 includes a disk-shaped base 61 and a suction holding chuck 62 formed in a disk shape by a porous ceramic material, and a work piece placed on the suction holding chuck 62 (holding surface). Is sucked and held by operating a suction means (not shown). The chuck table 6 configured as described above is rotated in a direction indicated by an arrow 6a by a servo motor 60 (not shown) as shown in FIG. The three chuck tables 6 arranged on the turntable 5 have a workpiece loading / unloading zone A, a rough grinding zone B, a finish grinding zone C, and a workpiece by appropriately rotating the turntable 5. It is sequentially moved to the loading / unloading area A.

  On the near side of the apparatus housing 2, a first cassette mounting portion 11a, a second cassette mounting portion 12a, a temporary placement portion 13a, and a cleaning portion 14a are provided. A first cassette 11 that accommodates a wafer before grinding is placed on the first cassette placement portion 11a, and a second cassette 12 that accommodates a wafer after grinding is placed on the second cassette placement portion 12a. It is supposed to be placed. The temporary placement unit 13a is provided with temporary placement means 13 for temporarily placing the unground wafer unloaded from the first cassette 11 placed on the first cassette placement unit 11a. The cleaning unit 14a is provided with cleaning means 14 for cleaning the ground wafer.

  A conveying means 15 is disposed between the first cassette placing portion 11a and the second cassette placing portion 12a, and the conveying means 15 is placed on the first cassette placing portion 11a. The unground wafer stored in the first cassette 11 is carried out to the temporary placing means 13 and the ground wafer cleaned by the cleaning means 14 is placed on the second cassette placing portion 12a. 2 to the second cassette 12. A carry-in means 16 is disposed between the temporary placement portion 13a and the workpiece loading / unloading area A, and this carry-in means 16 works the wafer before grinding placed on the temporary placement means 13 to be machined. It is transported onto the chuck table 6 positioned in the material loading / unloading area A. An unloading means 17 is disposed between the workpiece loading / unloading area A and the cleaning unit 14a. The unloading means 17 is placed on the chuck table 6 positioned in the workpiece loading / unloading area A. The mounted wafer after grinding is transported to the cleaning means 14.

  The illustrated grinding apparatus includes thickness measuring means 18a and 18b that are disposed adjacent to the rough grinding region B and the finish grinding region C, respectively, for detecting the thickness of the workpiece held on the chuck table 6. ing. The thickness measuring means 18a and 18b measure the thickness of the workpiece held in the chuck table and ground in the rough grinding area B and the finish grinding area C, and send a measurement signal to the control means described later.

  Further, the grinding apparatus in the illustrated embodiment includes an image pickup means 7 as a detection means for detecting a wafer carried into the chuck table 6 positioned in the workpiece carry-in / out area A by the carry-in means 16. . The image pickup means 7 is composed of a CCD camera, and is arranged in a transport path by the carry-in means 16 and picks up an image of a device formed on the wafer surface described later and outputs an image signal to a control means described later.

Next, another embodiment of an image pickup means as a detection means for detecting a wafer will be described with reference to FIG.
The imaging means 70 shown in FIG. 2 is disposed above the temporary placement means 13 provided in the temporary placement portion 13a. The image pickup means 70 is constituted by an infrared camera, picks up an image of a device formed on the front surface of the wafer placed on the temporary placement means 13 and outputs an image signal to a control means described later.

  The illustrated grinding apparatus includes the control means 8 shown in FIG. The control unit 8 includes a central processing unit (CPU) 81 that performs arithmetic processing according to a control program, a read-only memory (ROM) 82 that stores a control program and the like, and random access that can be read and written as a storage unit that stores calculation results and the like. A memory (RAM) 83, an input interface 84, and an output interface 85 are provided. Image signals from the thickness measuring means 18a and 18b, the imaging means 7 and / or the imaging means 70 are input to the input interface 84 of the control means 8 configured as described above. From the output interface 85, the servo motor 34 of the rough grinding unit 3 and the servo motor 44 of the finish grinding unit 4, the pulse motor 362 of the grinding feed means 36, the pulse motor 462 of the grinding feed means 46, and the chuck table 6 are provided. Control signals are output to the servo motor 60, the temporary storage means 13, the cleaning means 14, the transport means 15, the carry-in means 16, the carry-out means 17, and the like.

The grinding apparatus in the illustrated embodiment is configured as described above, and the operation thereof will be described below.
Here, a wafer as a workpiece will be described. FIG. 4 shows a perspective view of a semiconductor wafer as a wafer. A semiconductor wafer 10 shown in FIG. 4 is made of a silicon wafer, and devices 103 are formed in a plurality of regions partitioned by streets 101 and 102 formed in a lattice shape on a surface 10a. A plurality of types of semiconductor wafers 10 configured as described above are manufactured, and appropriate processing conditions are set for each. Therefore, when grinding with a grinding apparatus, it is necessary to detect the type of wafer and set processing conditions corresponding to the type of wafer. In order to distinguish the type of wafer, in the illustrated embodiment, a characteristic part such as a circuit forming the device 103 is set as a key pattern. For example, in the illustrated embodiment, the first semiconductor wafer 10A, the second semiconductor wafer 10B, the third semiconductor wafer 10C, the fourth semiconductor wafer 10D, and the fifth semiconductor wafer 10E are as shown in FIG. A key pattern is set for. Feature portion determination indicating correspondence between the first semiconductor wafer 10A, the second semiconductor wafer 10B, the third semiconductor wafer 10C, the fourth semiconductor wafer 10D, and the fifth semiconductor wafer 10E and the key pattern which is a feature portion The map is stored in a random access memory (RAM) 83 of the control means 8.

  Further, processing conditions are set for the first semiconductor wafer 10A, the second semiconductor wafer 10B, the third semiconductor wafer 10C, the fourth semiconductor wafer 10D, and the fifth semiconductor wafer 10E, respectively. . As processing conditions, in the illustrated embodiment, the rotation speed of the chuck table, the rotation speed of the grinding wheel, the grinding feed speed, and the thickness of the wafer are set. Such machining conditions are set for each wafer separately for rough grinding and finish grinding, and a machining condition map is created as shown in FIG. The machining condition map created in this way is stored in a random access memory (RAM) 83 of the control means 8.

Next, a procedure for grinding the semiconductor wafer 10 using the above-described grinding apparatus will be described.
First, as shown in FIGS. 5A and 5B, a protective tape T for protecting the device 103 is attached to the surface of the semiconductor wafer 10 (protective tape attaching step). As the protective tape T, a tape in which a transparent adhesive is applied to the surface of a transparent synthetic resin sheet is used in the illustrated embodiment. A plurality of semiconductor wafers 10 having the protective tape T attached to the front surface in this way are accommodated in the first cassette 11 with the back surface facing up. The plurality of semiconductor wafers 10 accommodated in the first cassette 11 include the first semiconductor wafer 10A, the second semiconductor wafer 10B, the third semiconductor wafer 10C, the fourth semiconductor wafer 10D, The fifth semiconductor wafer 10E may be mixed.

  As described above, the pre-grinding semiconductor wafer 10 accommodated in the first cassette 11 is transported to the temporary placement means 13 by the up-and-down operation and the advancing and retreating operation of the transport means 15, and is centered here. Next, the loading means 16 is operated to place the semiconductor wafer 10 centered in the temporary placing means 13 on the chuck table 6 positioned in the workpiece loading / unloading area A. In this way, when the semiconductor wafer 10 centered in the temporary placement means 13 by the carry-in means 16 is carried to the chuck table 6 positioned in the work-piece carry-in / out area A, the conveyance route by the carry-in means 16 is set. The arranged imaging means 7 is operated to image the device 103 formed on the surface of the semiconductor wafer 10 (wafer imaging process). That is, since the carry-in means 16 conveys the upper surface (rear surface) of the semiconductor wafer 10 while sucking and holding it, the image pickup means in which the protective tape T attached to the surface of the semiconductor wafer 10 is disposed in the conveyance path by the carry-in means 16. Passes 7 facing. Therefore, the imaging means 7 can image the device 103 formed on the surface of the semiconductor wafer 10 through the protective tape T made of a transparent body. The imaging means 7 that has imaged the device 103 formed on the surface of the semiconductor wafer 10 in this way sends an image signal to the control means 8. The control means 8 performs pattern matching based on the image signal sent from the image pickup means 7 and the feature part determination map shown in FIG. 6 and determines the type of the semiconductor wafer 10 imaged by the image pickup means 7 (wafer). Judgment process). Then, the control means 8 selects a processing condition corresponding to the determined type of the semiconductor wafer 10 from the processing condition map shown in FIG. 7 (processing condition selection step).

  On the other hand, as described above, the semiconductor wafer 10 placed on the chuck table 6 positioned in the workpiece loading / unloading area A is operated via a protective tape T by operating a suction means (not shown). Suction-held on top. Therefore, the back surface of the semiconductor wafer 10 sucked and held on the chuck table 6 via the protective tape T is the upper side. Next, the turntable 5 is rotated 120 degrees in the direction indicated by the arrow 5a by a rotation drive mechanism (not shown), and the chuck table 6 that sucks and holds the semiconductor wafer 10 is positioned in the rough grinding region B.

  When the chuck table 6 holding the semiconductor wafer 10 by suction is positioned in the rough grinding region B, the control means 8 performs rough grinding based on the processing conditions selected in the processing condition selection step. For example, when the type of the semiconductor wafer 10 is the first semiconductor wafer 10A in the wafer determination step, the rotation speed of the chuck table is 300 rpm and the grinding wheel is used as the rough grinding processing conditions in the processing condition selection step. The rotation speed is 4000 rpm, the grinding feed speed is 0.5 μm / second, and the wafer thickness is 105 μm. Therefore, the control means 8 controls the rotational speeds of the servo motor 60 that rotates the chuck table 6, the servo motor 34 of the rough grinding unit 3, and the pulse motor 362 of the grinding feed means 36 according to the machining conditions selected as described above. At the same time, the grinding feed amount of the grinding feed means 36 is controlled based on the detection signal from the thickness measuring means 18a. As a result, the semiconductor wafer 10 held on the chuck table 6 is roughly ground under an appropriate processing condition corresponding to the type of wafer.

  During this time, the semiconductor wafer 10 before grinding is placed on the next chuck table 6 positioned in the workpiece loading / unloading area A as described above. The semiconductor wafer 10 placed on the chuck table 6 is sucked and held on the chuck table 6 by operating a suction means (not shown). When the semiconductor wafer 10 before grinding is placed on the next chuck table 6 positioned in the workpiece loading / unloading area A, the control means 8 performs the wafer imaging step and determines the wafer determination. The process and the processing condition selection process are performed, and the type of the semiconductor wafer 10 to be processed next is determined and the processing conditions are selected.

  Next, the turntable 5 is rotated 120 degrees in the direction indicated by the arrow 5a, the chuck table 6 holding the semiconductor wafer 10 subjected to the rough grinding is positioned in the finish grinding area C, and the semiconductor wafer before grinding is placed. The chuck table 6 holding 10 is positioned in the rough grinding area B.

  In this way, the back surface (upper surface) of the semiconductor wafer 10 before being ground held on the chuck table 6 positioned in the rough grinding region B is subjected to rough grinding by the rough grinding unit 3 and finish grinding. A finish grinding unit 4 performs finish grinding on the back surface (upper surface) of the semiconductor wafer 10 held on the chuck table 6 positioned in the region C and roughly ground. At this time, the control means 8 performs finish grinding on the semiconductor wafer 10 held on the chuck table 6 positioned in the finish grinding region C and roughly ground based on the finish grinding conditions selected in the previous process condition selection step. The pre-grinding semiconductor wafer 10 held on the chuck table 6 positioned in the rough grinding area B is subjected to rough grinding based on the rough grinding conditions selected in the current machining condition selection step. carry out.

  During this time, on the next chuck table 6 positioned in the workpiece loading / unloading area A, the semiconductor wafer 10 before grinding is placed as described above. The semiconductor wafer 10 placed on the chuck table 6 is sucked and held on the chuck table 6 by operating a suction means (not shown). When the semiconductor wafer 10 before grinding is placed on the next chuck table 6 positioned in the workpiece loading / unloading area A, the control means 8 performs the wafer imaging step and determines the wafer determination. The process and the processing condition selection process are performed, and the type of the semiconductor wafer 10 to be processed next is determined and the processing conditions are selected.

  Next, the turntable 5 is rotated 120 degrees in the direction indicated by the arrow 5a, and the chuck table 6 holding the semiconductor wafer 10 subjected to finish grinding is positioned in the workpiece loading / unloading area A. The chuck table 6 holding the semiconductor wafer 10 that has been roughly ground in the rough grinding area B is held in the finish grinding area C, and the chuck table that holds the semiconductor wafer 10 before grinding in the work-in / out area A. 6 are moved to the rough grinding zone B, respectively. In this way, the rough grinding processing selected as described above by the rough grinding unit 3 is performed on the back surface (upper surface) of the semiconductor wafer 10 before grinding held on the chuck table 6 positioned in the rough grinding region B. As described above, the back surface (upper surface) of the semiconductor wafer 10 that has been subjected to rough grinding based on the conditions and held on the chuck table 6 positioned in the finish grinding region C and rough ground as described above by the finish grinding unit 4. Finish grinding is performed based on the selected finish grinding conditions.

  On the other hand, the chuck table 6 that has returned to the workpiece loading / unloading zone A via the rough grinding zone B and the finish grinding zone C releases the suction holding of the semiconductor wafer 10 that has been ground here. Next, the carry-out means 17 is operated to carry the ground semiconductor wafer 10 placed on the chuck table 6 positioned in the workpiece carry-in / out area A to the cleaning means 14. The semiconductor wafer 10 conveyed to the cleaning means 14 is spin-dried while the grinding scraps are cleaned and removed here. The semiconductor wafer 10 thus cleaned and spin-dried is transported and stored in the second cassette 12 by the transport means 15.

  Next, a wafer imaging process in the case where the protective tape T attached to the surface of the semiconductor wafer 10 is formed of a non-transparent member will be described. When the protective tape T is formed of a non-transparent member as described above, the device 103 formed on the surface of the semiconductor wafer 10 cannot be imaged through the protective tape T. An imaging means 70 composed of an infrared camera disposed above the placing means 13 is used. In other words, the imaging means 70 constituted by an infrared camera is formed on the front surface through the back surface of the semiconductor wafer 10 placed on the temporary placement means 13 (mounted on the back surface as described above). The device 103 is imaged and an image signal is output to the control means 8. Thus, since the imaging means 70 is composed of an infrared camera, even if the protective tape T is formed of a non-transparent member, the device 103 that is transmitted from the back surface of the semiconductor wafer 10 and formed on the surface thereof. Can be imaged. In addition, if the imaging means 70 comprised with the infrared camera is used, regardless of the material of the protection tape T, the semiconductor wafer 10 can be permeate | transmitted from the back surface, and the device 103 formed in the surface can be imaged.

2: equipment housing 3: rough grinding unit 33: rough grinding wheel 36: grinding feed means 4: finish grinding unit 43: finish grinding wheel 46: grinding feed means 5: turntable 6: chuck table 7: imaging means 8: control means DESCRIPTION OF SYMBOLS 10: Semiconductor wafer 11: 1st cassette 12: 2nd cassette 13: Temporary placing means 14: Cleaning means 15: Conveyance means 16: Loading means 17: Unloading means

Claims (3)

A chuck table having a holding surface for sucking and holding the wafer, a grinding means having a grinding wheel for grinding the wafer sucked and held by the holding surface of the chuck table, and the grinding means with respect to the holding surface of the chuck table In a grinding apparatus comprising: grinding feed means for grinding feed in a vertical grinding feed direction; and carry-in means for carrying a wafer before grinding to a holding surface of the chuck table.
Detection means for detecting a pre-grinding wafer that is carried into the chuck table by the carry-in means, control for determining the type of wafer detected by the detection means, and selecting processing conditions corresponding to the determined wafer type has been and means, the,
The detection means comprises imaging means for imaging a device formed on the wafer surface and outputting an image signal to the control means,
The control means performs pattern matching based on an image signal of a key pattern set as a characteristic part of a device formed on the surface of the wafer, and determines the type of the wafer.
A grinding apparatus characterized by that. The control means comprise a memory for storing the processing condition map which sets the machining conditions corresponding to the type of feature determination map and the wafer determines the type of the wafer set on the basis of the key pattern, the detection means A wafer type is determined by comparing the image signal from the device feature set in the feature determination map, and a processing condition corresponding to the determined wafer type is selected from the processing condition map. The grinding apparatus according to claim 1.   3. A temporary placement means for temporarily placing a pre-grinding wafer before being carried into the chuck table by the carry-in means, wherein the detection means detects the wafer temporarily placed on the temporary placement means. The grinding apparatus as described.

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