JP7328104B2 - Grinding equipment - Google Patents

Description

The present invention relates to grinding equipment.

As disclosed in Patent Documents 1 and 2, a grinding apparatus that grinds a wafer using a grindstone sucks and holds the upper surface of a ground wafer held on a chuck table using a transfer pad, and lifts the transfer pad. After separating the wafer from the chuck table by raising it, the wafer is transported to the spinner table, cleaned, and housed in a cassette. The transport means for transporting the wafer comprises an arm from which a transport pad for holding the wafer is suspended, and a vertical means for vertically moving the arm. The vertical means adjusts the height position of the arm so that the lower surface of the transfer pad contacts the upper surface of the wafer.

In a chuck table provided with a porous plate having a holding surface for holding a wafer, grinding debris generated during grinding of the wafer may enter the inside of the holding surface, reducing the suction force of the holding surface. Therefore, the suction force of the holding surface is restored by periodically performing so-called self-grinding of the holding surface using a whetstone to expose a new holding surface.
Grinding of the wafer is performed until a preset thickness is achieved while measuring the thickness of the wafer. In measuring the thickness of the wafer, a height gauge is used to measure the height of the holding surface and the height of the upper surface of the wafer held by the holding surface, and the difference between the measured values is calculated as the thickness of the wafer. .

JP 2008-073785 A JP 2015-039755 A

After self-grinding the holding surface of the chuck table as described above, the height of the holding surface is lowered. It may not be possible to contact the top surface of the wafer.
Further, if the height gauge fails, the thickness of the wafer recognized by the grinder may differ from the actual thickness of the wafer held on the chuck table and ground.
Therefore, in the conveying means of the grinding apparatus, the wafer is sucked and held using a conveying pad after self-grinding, and the ground wafer is detected to have a thickness different from the preset thickness. There is a problem of knowing the thickness to be solved.

The present invention comprises a chuck table that holds a wafer on a holding surface, a grinding means that grinds the wafer held on the holding surface using a grindstone, and a chuck that holds the upper surface of the wafer held on the chuck table by suction. A grinding apparatus comprising carrying-out means for carrying out the wafer from the holding surface, wherein the carrying-out means comprises a pad having a suction surface on the bottom surface for sucking and holding the top surface of the wafer, and the pad being vertically suspended. an arm for moving the arm, a vertical means for moving the arm in a direction perpendicular to the suction surface, an approach detector for detecting that the arm and the pad have approached each other, and the vertical means for adjusting the height of the arm. The arm is lowered using the up-and-down means so that the lower surface of the pad comes into contact with the holding surface, and then the arm is further lowered so that the arm and the pad are separated by a predetermined distance. A grinding apparatus comprising a height setting unit for setting the height of the arm when the proximity detection unit detects the approach as the height of the arm when sucking and holding the wafer held on the chuck table. be.
The above-described grinding apparatus comprises a judgment means for judging whether or not the wafer ground by the grindstone has a predetermined thickness, and the judgment means lowers the arm using the vertical means to suck the wafer. The arm recognized by the height recognition section when the approach detection section detects that the surface is brought into contact with the holding surface, the arm is further lowered, and the arm and the pad come closer to each other by a predetermined distance. and a holding surface height storage unit for storing the height of the holding surface, and the lifting means to lower the arm to bring the suction surface into contact with the upper surface of the wafer held by the holding surface, and then lower the arm. The height of the arm recognized by the height recognizing section when the approach detecting section detects that the arm and the pad approach each other by a predetermined distance is taken as the top surface height of the wafer. A thickness calculation unit that calculates the thickness of the wafer by subtracting the holding surface height stored in the holding surface height storage unit from the thickness, and the thickness calculated by the thickness calculation unit is a preset thickness tolerance. and a judgment unit for judging whether or not it is within the range.
The vertical means of the grinding apparatus lowers the arm from the uppermost position at high speed to a height position a predetermined distance above the height position set in the height setting section. It is desirable to descend at a low speed from a height position a predetermined distance above the set height position to the height position set in the height setting section.

When the approach detection unit detects that the arm and the pad approach each other in the vertical direction by a predetermined distance when the lower surface of the pad is pushed down to the holding surface with no wafer placed on the holding surface, the height of the arm is detected. By lowering the arm with the wafer placed on the holding surface to a height set in advance as the height position, the lower surface of the pad can be reliably brought into contact with the upper surface of the wafer, and the wafer is suction-held on the pad. can do.
The height of the upper surface of the wafer after grinding is measured, and the thickness of the wafer is calculated by subtracting the height of the holding surface stored in the holding surface height storage unit from the measured upper surface height of the wafer. can do. This makes it possible to know that the wafer has been ground to a thickness different from the preset thickness when, for example, the holding surface height gauge or upper surface height gauge of the thickness measuring means fails.
In addition, in lowering the arm, since the arm is lowered at high speed from the uppermost position of the arm to, for example, the height of the arm when the lower surface of the pad is positioned slightly above the upper surface of the wafer, It is possible to shorten the time required for the vertical movement of the arm, and reduce the time cost required for wafer grinding.
Since the arm is lowered at a relatively low speed from the height position of the arm when the lower surface of the pad is positioned slightly above the upper surface of the wafer to the height position set in the height setting section, the wafer is lowered. It is possible to prevent the wafer from being damaged when it is sandwiched between the lower surface of the pad and the holding surface and pressed from above and below.

It is a perspective view showing the whole grinding device. FIG. 4 is a side cross-sectional view of the carrying-out means and the chuck table; FIG. 10 is a side cross-sectional view showing how the carry-out means is used to store the height of the holding surface of the chuck table; FIG. 4 is a side cross-sectional view showing how the wafer thickness is measured and the wafer is unloaded using unloading means;

1 Configuration of Grinding Apparatus A grinding apparatus 1 shown in FIG. 1 is a grinding apparatus that grinds a wafer W using a grindstone 340 . The configuration of the grinding apparatus will be described below.

As shown in FIG. 1, the grinding apparatus 1 includes a base 10 extending in the Y-axis direction and a column 11 standing on the +Y direction side of the base 10 .
The region on the +Y direction side on the base 10 is the loading/unloading region A where the wafer W is loaded and unloaded, and the region on the -Y direction side on the base 10 is the grinding region where the wafer W is ground. It is B.

A chuck table 2 is arranged on the base 10 . The chuck table 2 includes a disk-shaped suction portion 20 and an annular frame 21 that supports the suction portion 20 . The upper surface of the suction unit 20 serves as a holding surface 20a on which the wafer W is held. The holding surface 20a and the upper surface 21a of the frame 21 are flush with each other.
A suction means (not shown) or the like is connected to the holding surface 20a. In a state where the wafer W is placed on the holding surface 20a, a suction means or the like (not shown) is used to exert a suction force, whereby the generated suction force is transmitted to the holding surface 20a, and the wafer is held on the holding surface 20a. W is attracted and held.

The chuck table 2 is rotatable about a rotation axis 25 passing through the center of the chuck table 2 in the Z-axis direction by rotating means or the like (not shown).

Horizontal movement means for horizontally moving the chuck table 2 in the Y-axis direction is provided inside the base 10 .
Further, a cover 27 and a bellows 28 connected to the cover 27 so as to extend and contract are provided around the chuck table 2 . For example, when the chuck table 2 is moved in the Y-axis direction by horizontal movement means or the like, the cover 27 moves in the Y-axis direction together with the chuck table 2, and the bellows 28 expands and contracts.

For example, a thickness measuring means 100 is arranged on the base 10 . The thickness measuring means 100 has a holding surface height gauge 101 . For example, by bringing the probe of the holding surface height gauge 101 into contact with the upper surface 21a of the frame 21, the height of the holding surface 20a of the suction unit 20 flush with the upper surface 21a of the frame 21 can be measured.
The thickness measuring means 100 has an upper surface height gauge 102 . For example, the height of the upper surface Wa of the wafer W can be measured by bringing the probe of the upper surface height gauge 102 into contact with the upper surface Wa of the wafer W while the wafer W is held on the holding surface 20a.
The thickness of the wafer W can be calculated by subtracting the height of the holding surface 20a measured by the holding surface height gauge 101 and the height of the upper surface Wa of the wafer W measured by the upper surface height gauge 102 using thickness calculating means (not shown). .

Grinding feed means 4 for supporting the grinding means 3 so as to move up and down is arranged on the side surface of the column 11 in the -Y direction. The grinding means 3 includes a spindle 30 having a rotating shaft 35 in the Z-axis direction, a housing 31 rotatably supporting the spindle 30, a spindle motor 32 rotating the spindle 30 about the rotating shaft 35, and the spindle 30. It has an annular mount 33 connected to the lower end thereof, and a grinding wheel 34 detachably attached to the lower surface of the mount 33 .
The grinding wheel 34 includes a wheel base 341 and a plurality of substantially rectangular parallelepiped grindstones 340 annularly arranged on the lower surface of the wheel base 341. The lower surface of the grindstone 340 is a grinding surface 340a for grinding the wafer W. It has become.

The grinding feed means 4 includes a ball screw 40 having a rotating shaft 45 extending in the Z-axis direction, a pair of guide rails 41 arranged parallel to the ball screw 40, and a Z-rotor rotating the ball screw 40 around the rotating shaft 45. It comprises a shaft motor 42 , an elevating plate 43 having an internal nut screwed onto the ball screw 40 and having side portions in sliding contact with the guide rails 41 , and a holder 44 connected to the elevating plate 43 and supporting the grinding means 3 .

When the ball screw 40 is driven by the Z-axis motor 42 and rotates about the rotating shaft 45, the elevator plate 43 is guided by the guide rail 41 and moves up and down in the Z-axis direction. The grinding means 3 held by the holder 44 moves in the Z-axis direction.

A cassette mounting portion 12 is provided on the -Y direction side of the base 10 .
A cassette 70 is mounted on the cassette mounting portion 12 . The cassette 70 contains wafers W before grinding. Further, the cassette 70 can accommodate the wafer W after grinding.

A robot 71 is arranged on the +Y direction side of the cassette 70 . The robot 71 includes a robot hand 710 and a shaft portion 711 that rotatably supports the robot hand 710 . The wafer W stored in the cassette 70 is taken out from the cassette 70 using the robot hand 710, and the wafer W can be transported by turning the robot hand 710 around the shaft portion 711. FIG.

On the +X direction side of the movable range of the robot hand 710, there is provided a temporary placement area 13 in which the wafer W before grinding is temporarily placed. A cleaning area 14 is provided for cleaning the wafer W after grinding.

Positioning means 72 are arranged in the temporary placement area 13 . The wafer W unloaded from the cassette 70 and placed on the temporary placement area 13 is aligned at a predetermined position by the alignment means 72 .

A spinner cleaning means 73 is provided in the cleaning area 14 . The spinner cleaning means 73 includes a spinner table 730 that holds and rotates the wafer W, and a cleaning water supply nozzle 731 that jets cleaning water toward the wafer W held on the spinner table 730 .
The wafer W can be cleaned by supplying cleaning water from the cleaning water supply nozzle 731 while the wafer W after grinding is placed on the spinner table 730 .

At a position adjacent to the temporary placement area 13, a loading means 74 for loading the wafer W aligned by the alignment means 72 onto the chuck table 2 is provided. The loading means 74 includes a loading pad 740 for sucking and holding the wafer W, a loading arm 741 whose end is connected to the loading pad 740, and a loading arm 741 connected to the end not connected to the loading pad 740 to rotate. and a shank 742 for possible support.
The shaft portion 742 is driven by a rotating means or the like (not shown) and is rotatable about a rotating shaft 745 in the Z-axis direction. The loading arm 741 and the loading pad 740 pivotally move between the loading/unloading area A and the grinding area B by rotating the shaft portion 742 .
When the shaft portion 742 rotates in a state where the wafer W is sucked and held by the loading pad 740, the loading arm 741 and the loading pad 740 connected to the loading arm 741 rotate about the rotating shaft 745, thereby causing the wafer W to rotate. can be carried into the holding surface 20 a of the chuck table 2 .

The carry-out means 5 is arranged near the -X direction side of the carry-in means 74 .
The carry-out means 5 includes a disk-shaped pad 50 and an arm 51 that vertically suspends the pad 50 . A tubular shaft portion 510 having a rotating shaft 55 in the Z-axis direction is connected to the end portion 51a of the arm 51 . For example, the shaft portion 510 is connected to rotating means (not shown) for rotating the shaft portion 510 about the rotating shaft 55 .

An annular member 52 is connected to the end portion 51 b of the arm 51 that is not connected to the shaft portion 510 . For example, three through holes 520 are formed through the annular member 52 at equal intervals on the circumference. Only one through-hole 520 is illustrated in FIG. 1, and the other two through-holes 520 are omitted.

As shown in FIG. 2 , the pad 50 includes a suction portion 500 having many pores and a frame 501 supporting the suction portion 500 . The lower surface of the suction unit 500 serves as a suction surface 500b for holding the upper surface Wa of the wafer W by suction. The lower surface 50b of the pad 50 has a suction surface 500b of the suction portion 500 and a lower surface 501b of the frame 501 flush with the suction surface 500b.

The carry-out means 5 has a number of suspension parts 56 corresponding to the number of through-holes 520 of the annular member 52 (for example, three, and two are shown in FIG. 2). The suspension portion 56 has a function of connecting the pad 50 and the annular member 52 .
The suspension portion 56 includes a shaft portion 560 having a diameter slightly smaller than the diameter of the through hole 520 and a flange portion 561 formed at the upper end of the shaft portion 560 .
The shafts 560 are loosely fitted through the respective through holes 520 , and the lower ends of the shafts 560 are connected to the upper surface 501 a of the frame 501 of the pad 50 . The suspending portion 56 is, for example, a stripper bolt or the like. For example, a screw hole (not shown) formed in the upper surface 501a of the frame 501 of the pad 50 is threaded with a threaded portion (not shown) formed at the bottom of the shaft portion 560. Together, it is assumed that the suspending portion 56 is fastened to the pad 50 .
The flange portion 61 is formed to have a larger diameter than the through hole 520 and limits the lowering range of the suspension portion 56 .

A spring 562 is wound around the shaft portion 560 of the suspension portion 56 . The upper end 562 a of the spring 562 contacts the lower surface 52 b of the annular member 52 , and the lower end 562 b of the spring 562 contacts the upper surface 501 a of the frame 501 of the pad 50 .

When the shaft portion 510 rotates about the rotation shaft 55 by rotating means or the like (not shown), the arm 51 , the annular member 52 connected to the arm 51 , and the annular member 52 are connected via the suspending portion 56 . The pad 50 rotates integrally around the rotating shaft 55 .

The carry-out means 5 has a pipe 57 . The pipe 57 is arranged, for example, so as to pass through the frame 501 of the pad 50 , and its lower end is connected to the suction portion 500 . The pipe 57 branches into an air flow path 581 and a suction path 591 at a branch point a.
The suction part 500 is connected to the air supply source 58 through the pipe 57 and the air flow path 581 . An air valve 580 for switching the state of communication between the air supply source 58 and the suction portion 500 is arranged in the air flow path 581 .
Also, the suction unit 500 is connected to the suction source 59 through a pipe 57 and a suction path 591 . A suction valve 590 for switching the state of communication between the suction source 59 and the suction section 500 is arranged in the suction path 591 .

For example, in a state in which the upper surface Wa of the wafer W is in contact with the suction surface 500b of the suction unit 500, the suction valve 590 is opened and the suction source 59 is operated to generate a suction force. It is transmitted to the suction surface 500b of the suction unit 500 through the suction path 591 and the pipe 57, and the wafer W is suction-held on the suction surface 500b of the suction unit 500. FIG.

Further, for example, if grinding debris or the like generated by the grinding process of the wafer W adheres to the suction surface 500b of the suction portion 500 of the pad 50, or if processing debris or the like enters the many pores of the suction portion 500, The suction unit 500 is clogged, and the suction force acting on the suction unit 500 is impaired. Therefore, for example, after grinding the wafer W, the air valve 580 is opened and the air supply source 58 is operated while the wafer W is not suction-held on the suction surface 500b of the pad 50, so that the air flow path 581 and Air is supplied to the suction unit 500 through the pipe 57 and jetted from the suction surface 500b to clean the inside of the suction unit 500 and the suction surface 500b.

The unloading means 5 is equipped with a vertical means 6 . The vertical means 6 includes a ball screw 60 having a rotation shaft 65 extending in the Z-axis direction, a nut portion 66 screwed onto the ball screw 60 and connected to a shaft portion 510, and a pair of vertical shafts arranged parallel to the ball screw 60. A guide rail 61 and a motor 62 arranged at the upper end of the ball screw 60 for rotating the ball screw 60 around a rotating shaft 65 are provided. By using the motor 62 to rotate the ball screw 60 about the rotary shaft 65, the shaft portion 510 and the arm 51 can be vertically moved in the direction (Z-axis direction) perpendicular to the suction surface 500b.

For example, in a state where the chuck table 2 on which the wafer W is placed on the holding surface 20a is positioned below the carry-out means 5, the arm 51 is lowered in the -Z direction using the up-and-down means 6, whereby the arm The pad 50 suspended from 51 can be lowered so that the lower surface 50b thereof contacts the upper surface Wa of the wafer W. As shown in FIG.
When the lower surface 50b of the pad 50 is in contact with the wafer W or the like and the arm 51 is further lowered in the -Z direction using the vertical means 6, the suction surface 500b of the suction portion 500 of the pad 50 lifts the wafer. W and the like are pushed in the -Z direction, and as a reaction force to the pushing force, the suction surface 500b of the pad 50 receives a pushing force in the +Z direction from the wafer W and the like. As a result, the pad 50 and the suspension portion 56 are integrally lifted in the +Z direction, and the flange portion 561 is lifted above the upper surface 52a of the annular member 52, and the spring 562 is moved between the pad 50 and the arm 51. will contract between

The vertical means 6 moves the arm 51 at a low speed to a height position a predetermined distance above the height set in the height setting section 9, and moves the arm 51 to a height position a predetermined distance above the set height. to the highest position at high speed.
The height position above a predetermined distance from the height position set in the height setting unit 9 is, for example, the lower surface 50b of the pad 50 positioned slightly above the upper surface Wa of the wafer W held on the holding surface 20a. and the height position of the arm 51 when it is

The up-and-down means 6 has a height recognition part 63 . The height recognition unit 63 is, for example, an encoder or the like, and is mounted on the motor 62 .
The height recognizing section 63 may have a scale and a reading section (not shown) arranged on the guide rail 61 instead of the encoder.

The carry-out means 5 includes a light projecting/receiving sensor 53 . A light emitting/receiving sensor 53 is arranged on the arm 51 or the pad 50 . The light emitting/receiving sensor 53 is arranged on the lower surface 52b of the annular member 52 connected to the arm 51, for example. The light projecting/receiving sensor 53 includes a light projecting section 530 that projects light, and a light receiving section 531 that is arranged opposite to the light projecting section 530 and receives the light projected from the light projecting section 530 .

The carry-out means 5 includes a plate-shaped dog 54 having a light shielding property. The dog 54 is arranged, for example, on the upper surface 501 a of the frame 501 of the pad 50 so as to face the light emitting/receiving sensor 53 .

The positional relationship between the light emitting/receiving sensor 53 and the dog 54 in the carry-out means 5 is not limited to the illustrated example. For example, the light emitting/receiving sensor 53 is arranged on the upper surface 501a of the frame 501 of the pad 50, and the dog 54 is arranged on the lower surface 52b of the annular member 52 of the arm 51 so as to face the light emitting/receiving sensor 53. may

For example, when the lower surface 50b of the pad 50 is in contact with the holding surface 20a or the like and the arm 51 is driven by the vertical means 6 to descend in the -Z direction, the pad 50 suspended by the arm 51 is held. The dog 54 erected on the upper surface 501a of the frame body 501 of the pad 50 moves upward in the +Z direction with respect to the arm 51. Rise.
As a result, when the upper end 54 a of the dog 54 rises to the height of the linear optical axis L connecting the light projecting portion 530 and the light receiving portion 531 of the light projecting/receiving sensor 53 , the dog 54 blocks the optical axis L.
When the optical axis L of the light projecting/receiving sensor 53 is blocked by the dog 54 and the light receiving portion 531 no longer receives light from the light projecting portion 530, an electric signal is transmitted from the light projecting/receiving sensor 53 to the height recognition portion 63. , the height of the arm 51 at that time is recognized by the height recognition unit 63 .
In this manner, the light emitting/receiving sensor 53 and the dog 54 constitute an approach detection section that detects that the pad 50 and the arm 51 approach in the Z-axis direction, which is the vertical direction.

The grinding device 1 has a height setting section 9 . The height setting unit 9 lowers the arm 51 in the -Z direction using the up-and-down means 6 as described above in a state in which the wafer W or the like is not held on the holding surface 20a, so that the dog 54 moves toward the light beam. The height of the arm 51 when the axis L is interrupted can be set as the height of the arm 51 when the wafer W held on the chuck table 2 is held on the pad 50 by suction.

The grinding apparatus 1 includes a judgment means 8 for judging whether or not the wafer W ground by the grindstone 340 has a preset thickness. The determination means 8 has, for example, a CPU, a memory, and the like.

The determination means 8 has a holding surface height storage section 80 . In the holding surface height storage unit 80, the arm 51 is lowered using the up-and-down means 6 to bring the suction surface 500b into contact with the holding surface 20a. It is possible to store the height of the arm 51 recognized by the height recognition unit 63 when the is interrupted.

The determination means 8 has a thickness calculator 81 .
For example, by lowering the arm 51 using the vertical means 6, the suction surface 500b of the pad 50 contacts the upper surface Wa of the wafer W held on the holding surface 20a. After the suction surface 500b of the pad 50 contacts the upper surface Wa of the wafer W, the arm 51 is further lowered so that the dog 54 blocks the optical axis L. It is recognized by the height recognition unit 63 as the height of the upper surface Wa. The thickness calculator 81 can calculate the thickness of the wafer W by subtracting the height of the holding surface 20a stored in the holding surface height storage unit 80 from the height of the upper surface Wa of the wafer W.

The determination means 8 has a determination section 82 . The determination unit 82 can determine whether or not the thickness calculated by the thickness calculation unit 81 is within a preset allowable thickness range.

2 Operation of Grinding Device The operation of the grinding device 1 when the wafer W is ground using the grinding device 1 will be described below.

First, as shown in FIG. 1, in a state in which the chuck table 2 is not holding the wafer W by suction, the chuck table 2 is moved in the -Y direction by using horizontal movement means (not shown) or the like, and the unloading means 5 is moved. Position downwards. Then, by lowering the arm 51 in the -Z direction using the vertical means 6, the suction surface 500b of the pad 50 is brought into contact with the holding surface 20a of the chuck table 2, as shown in FIG.

While the suction surface 500b and the holding surface 20a are in contact with each other, the arm 51 is further lowered in the -Z direction. As a result, the suction surface 500 b receives a +Z-direction pressing force from the holding surface 20 a , and the pad 50 , the suspension portion 56 , and the dog 54 provided on the upper surface 501 a of the frame 501 of the pad 50 are attached to the arm 51 . On the other hand, it rises in the +Z direction.
As the dog 54 rises with respect to the arm 51, as shown in FIG. L is blocked. When the dog 54 blocks the optical axis L and the light projected from the light projecting portion 350 is no longer received by the light receiving portion 351 , the height of the arm 51 at that time is recognized by the height recognition portion 63 . In this manner, the approach detection unit comprising the light projecting/receiving sensor 53 and the dog 54 detects that the pad 50 and the arm 51 have come closer to each other by a predetermined distance in the Z-axis direction.

The height of the arm 51 recognized by the height recognition unit 63 is the height of the arm 51 when the wafer W held on the holding surface 20a of the chuck table 2 is sucked and held by the pad 50 in the height setting unit 9. is preset as
By setting the height of the arm 51 after bringing the suction surface 500b of the pad 50 into contact with the holding surface 20a and lowering the arm in this manner, even if the height of the holding surface 20a is lowered by self-grinding, Also, the wafer W can be reliably held.

Further, the height of the arm 51 recognized by the height recognition unit 63 is stored in the holding surface height storage unit 80 as the height of the holding surface 20a.
The height of the holding surface 20a stored in the holding surface height storage unit 80 is transmitted to the thickness calculation unit 81, for example, as an electric signal.

After storing the height of the holding surface 20a as described above, one wafer W stored in the cassette 70 is taken out using the robot 71 shown in FIG. The wafer W placed in the temporary placement area 13 is aligned at a predetermined position by the alignment means 72 .

Next, the wafer W aligned in the temporary storage area 13 is held by the loading pad 740 of the loading means 74, and the loading arm 741 and the loading pad 740 are rotated about the shaft portion 742, thereby loading the wafer W. The wafer W held on the pad 740 is moved from the temporary placement area 13 to the holding surface 20 a of the chuck table 2 .

While the wafer W is placed on the holding surface 20a, suction means (not shown) connected to the holding surface 20a is used to exert a suction force. As a result, the generated suction force is transmitted to the holding surface 20a, and the wafer W is held by suction on the holding surface 20a.

While the wafer W is being sucked and held on the holding surface 20a, the chuck table 2 is moved in the +Y direction using horizontal movement means (not shown) so that the chuck table 2 and the holding surface 20a of the chuck table 2 are sucked and held. The wafer W is positioned below the grinding means 3 .

With the chuck table 2 and the wafer W suction-held on the holding surface 20a of the chuck table 2 positioned below the grinding means 3, the chuck table is rotated around the rotary shaft 25 by rotating means (not shown) or the like. Rotate 2. As a result, the wafer W sucked and held on the holding surface 20a rotates around the rotating shaft 25. As shown in FIG.

Further, the spindle motor 32 is used to rotate the spindle 30 around the rotating shaft 35 . As a result, the grindstone 340 rotates around the rotating shaft 35 .

The wafer W sucked and held on the holding surface 20a is rotating about the rotating shaft 25, and the grindstone 340 is rotating about the rotating shaft 35. 340 is lowered in the -Z direction.

When the grindstone 340 is driven by the grinding feed means 4 to move in the -Z direction, the grinding surface 340a of the grindstone 340 comes into contact with the upper surface Wa of the wafer W held by the holding surface 20a. With the grinding surface 340a of the grindstone 340 in contact with the upper surface Wa of the wafer W, the grindstone 340 is further lowered in the -Z direction using the grinding feed means 4, thereby grinding the upper surface Wa of the wafer W.

During the grinding process of the wafer W, the thickness of the wafer W is measured by the thickness measuring means 100 . Specifically, the holding surface height gauge 101 and the upper surface height gauge 102 are brought into contact with the upper surface 21a of the frame 21 and the upper surface Wa of the wafer W, respectively, and the difference in height between the two is calculated as the thickness of the wafer W.
When the thickness of the wafer W reaches a predetermined thickness by grinding, the grindstone 340 is lifted in the +Z direction using the grinding feed means 4 to separate the grindstone 340 from the upper surface Wa of the wafer W, and a rotating means (not shown). etc. to stop the rotation of the chuck table 2 .

Next, the chuck table 2 and the wafer W held on the holding surface 20a of the chuck table 2 are moved in the -Y direction using a horizontal moving means or the like (not shown), and the wafer W held on the holding surface 20a is unloaded. Positioned in the range of motion of pad 50 of means 5 .

Then, as shown in FIG. 4, the arm 51 is lowered in the -Z direction to a height position previously set in the height setting section 9 by using the up-and-down means 6 .

When lowering the arm 51 to the height position set in the height setting section 9 in advance, the uppermost position of the arm 51 is first lowered by a predetermined distance above the height position set in the height setting section 9. , that is, the height of the arm 51 when the suction surface 500b of the pad 50 is positioned slightly above the upper surface Wa of the wafer W, the arm 51 is moved at high speed in the -Z direction.
Then, the arm 51 is relatively moved from the height position of the arm 51 when the suction surface 500b of the pad 50 is positioned slightly above the upper surface Wa of the wafer W to the height position set in the height setting unit 9. Move in the -Z direction at low speed. Then, the suction surface 500b of the pad 50 comes into contact with the upper surface Wa of the wafer W before long.

Even after the suction surface 500b of the pad 50 comes into contact with the upper surface Wa of the wafer W as described above, when the arm 51 is lowered, the suction surface 500b receives a pressing force in the +Z direction from the upper surface Wa of the wafer W. As a result, the pad 50, the suspension portion 56, and the dog 54 provided on the upper surface 501a of the frame 501 of the pad 50 rise in the +Z direction with respect to the arm 51. As shown in FIG.
When the dog 54 rises by a predetermined height with respect to the arm 51 , the dog 54 blocks the optical axis L of the light projecting/receiving sensor 53 . When the optical axis L is blocked and the light projected from the light projecting section 350 is no longer received by the light receiving section 351, the height recognition section 63 recognizes the height of the arm 51 at that time. The height of the arm 51 at this time is also desirably stored in a storage unit (not shown). In this manner, the approach detection unit comprising the light projecting/receiving sensor 53 and the dog 54 detects that the pad 50 and the arm 51 have come closer to each other by a predetermined distance in the Z-axis direction.

The height of the arm 51 recognized by the height recognition unit 63 is transmitted to the thickness calculation unit 81 as the height of the upper surface Wa of the wafer W. FIG. Then, the thickness calculator 81 calculates the height of the arm 51 as the height of the holding surface 20a received in advance before grinding the wafer W from the height of the arm 51 received as the height of the upper surface Wa of the wafer W. By subtracting, the thickness of the wafer W is calculated.

Further, the determination unit 82 determines whether the thickness of the wafer W calculated by the thickness calculation unit 81 is within a preset allowable thickness range.

When the judgment unit 82 judges that the thickness calculated by the thickness calculation unit 81 is within the preset allowable thickness range, the wafer W is unloaded.

When unloading the wafer W, first, the suction means (not shown) connected to the chuck table 2 is stopped to remove the suction force acting on the holding surface 20a.

Then, the arm 51 is lowered to a preset height position using the up-and-down means 6 . Here, as described above, the preset height position is such that when the arm 51 is pushed down onto the holding surface 20a with no wafer W placed on the holding surface 20a, the dog 54 is aligned with the optical axis L. is the height position of the arm 51 when the pad 50 is interrupted. The lower surface 50b of the is in contact with the upper surface Wa of the wafer W reliably.
With the arm 51 positioned at a preset height position and the lower surface 50b of the pad 50 in contact with the upper surface Wa of the wafer W, the suction valve 590 is opened and the suction source 59 is operated. The suction force applied is transmitted to the suction portion 500 of the pad 50 through the suction path 591 and the pipe 57, and the upper surface Wa of the wafer W is suction-held on the suction surface 500b of the pad 50. FIG.

Then, the arm 51 is lifted and rotated while the wafer W is held by the pad 50 by suction, and the wafer W is moved from the holding surface 20a of the chuck table 2 to the cleaning area 14 shown in FIG. Then, the upper surface Wa of the wafer W is cleaned using the spinner cleaning means 73 in the cleaning area 14 . After that, the wafer W is accommodated in the cassette 70 using the robot 71 .

In the grinding process of the wafer W by the grinding apparatus 1, when the lower surface 50b of the pad 50 is pushed down onto the holding surface 20a in a state where the wafer W is not placed on the holding surface 20a, the dog 54 blocks the optical axis L. The height position of the arm 51 when the wafer W is held on the pad 50 is defined as the height position of the arm 51 when the wafer W is held by suction on the pad 50 . Therefore, when the wafer W is unloaded, when the arm 51 is lowered to the preset height position while the wafer W is placed on the holding surface 20a, the upper surface Wa of the wafer W and the lower surface of the pad 50 are brought into contact with each other. 50b can be reliably brought into contact.
Therefore, for example, even if the holding surface 20a is self-grinded and the height position of the holding surface 20a is lower than the predetermined position, the suction surface 500b of the pad 50 sucks and holds the upper surface Wa of the wafer W. can.

Further, according to the carry-out means 5, the height of the upper surface Wa of the wafer W after grinding is measured, and the measured height of the upper surface Wa of the wafer W is stored in the holding surface height storage unit 80. The thickness of the wafer W can be calculated by subtracting the height of the holding surface 20a.
As a result, when, for example, the holding surface height gauge 101 or the upper surface height gauge 102 of the thickness measuring means 100 fails, it can be known that the wafer has been ground to a thickness different from the preset thickness.

Furthermore, when the arm 51 is lowered to the height position set in the height setting unit 9 using the up-and-down means 6, for example, the lower surface 50b of the pad 50 is moved from the uppermost position of the arm 51 to the upper surface Wa of the wafer W. Since the arm 51 is moved at high speed in the -Z direction to the height position of the arm 51 when positioned slightly above from the Time cost for grinding can be reduced.
Then, the arm 51 is relatively moved from the height position of the arm 51 when the suction surface 500b of the pad 50 is positioned slightly above the upper surface Wa of the wafer W to the height position set in the height setting unit 9. Since the wafer W is moved in the -Z direction at a low speed, it is sandwiched between the lower surface 50b of the pad 50 and the holding surface 20a when the wafer W contacts the lower surface 50b of the pad 50 and after the wafer W contacts the lower surface 50b of the pad 50. It is possible to prevent the wafer W from being damaged when it is pressed from above and below.

In the present embodiment, the approach detection unit is composed of the light emitting/receiving sensor 53 and the dog 54, but the approach detection unit is not limited to this configuration.

1: Grinding Device 10: Base 11: Column 100: Thickness Calculating Means 101: Holding Surface Height Gauge 102: Upper Surface Height Gauge 12: Cassette Mounting Section 13: Temporary Placement Area 14: Washing Area 2: Chuck Table 20: Suction Unit 20a: Holding Surface 21: Frame 21: Upper surface of frame 25: Rotating shaft 27: Cover 28: Bellows 3: Grinding means 30: Spindle 31: Housing 32: Spindle motor 33: Mount 34: Grinding wheel 340: Grindstone 340a: Grinding surface 341: Wheel base 35: Rotating shaft 4: Grinding feeding means 40: Ball screw 41: Guide rail 42: Z-axis motor 43: Elevating plate 44: Holder 45: Rotating shaft 5: Carrying out means 50: Pad 50b: Lower surface of pad 500: Suction Part 500b: Suction surface 501: Frame 501a: Upper surface of frame 501b: Lower surface of frame 51: Arm 51a: One end of arm 51b: Other end of arm 510: Axle 52: Annular member 52a: Upper surface of annular member 52b : Lower surface of annular member 520: Through hole 521: Opening 53: Light emitting/receiving sensor 530: Light emitting part 531: Light receiving part 54: Dog 54a: Upper end of dog 55: Rotating shaft 56: Hanging part 560: Shaft part 561: Collar Part 562: Spring 562a: Upper end of spring 562b: Lower end of spring 57: Piping a: Branch point 58: Air supply source 580: Air valve 581: Air flow path 59: Suction source 590: Suction valve 591: Suction passage 6: Vertical means 60: Ball screw 61: Guide rail 62: Motor 63: Height recognition part 65: Rotating shaft 66: Nut 70: Cassette 71: Robot 710: Robot hand 711: Shaft part 72: Positioning means 73: Spinner cleaning means 730: Spinner Table 731: Cleaning water supply nozzle 74: Carrying-in means 740: Carrying-in pad 741: Carrying-in arm 742: Axle 745: Rotating shaft 8: Judging means 80: Holding surface height storage unit 81: Thickness calculator 82: Judging unit 9: Height setting part W: Wafer Wa: Upper surface of wafer A: Loading/unloading area B: Processing area L: Optical axis

Claims (3)

a chuck table for holding a wafer on a holding surface; a grinding means for grinding the wafer held on the holding surface using a grindstone; A grinding apparatus comprising a carrying-out means for carrying out a wafer,
The unloading means includes a pad having a suction surface on the bottom surface for sucking and holding the top surface of the wafer, an arm for vertically suspending the pad, and vertical means for moving the arm in a vertical direction perpendicular to the suction surface. and an approach detection unit that detects that the arm and the pad approach in the vertical direction,
The up-and-down means includes a height recognition unit that recognizes the height of the arm,
By lowering the arm using the vertical means, the lower surface of the pad comes into contact with the holding surface, and then the arm is further lowered so that the arm and the pad approach each other in the vertical direction by a predetermined distance. A grinding apparatus comprising a height setting unit for setting the height of the arm when the proximity detection unit detects the height of the arm when the wafer held on the chuck table is sucked and held. Determining means for determining whether the wafer ground using the grindstone has a preset thickness,
The determination means is
The arm is lowered using the vertical means to bring the suction surface into contact with the holding surface, and the arm is further lowered to detect that the arm and the pad have approached each other in the vertical direction by a predetermined distance. a holding surface height storage unit that stores the height of the arm recognized by the height recognition unit when the is detected;
The arm is lowered using the vertical means to bring the suction surface into contact with the upper surface of the wafer held by the holding surface, and the arm is further lowered so that the arm and the pad are separated in the vertical direction by a predetermined distance. The height of the arm recognized by the height recognition unit when the approach detection unit detects the approach is set as the top surface height of the wafer, and stored in the holding surface height storage unit from the wafer top surface height. a thickness calculation unit that calculates the thickness of the wafer by subtracting the holding surface height that has been set,
2. The grinding apparatus according to claim 1, further comprising a judgment section for judging whether the thickness calculated by said thickness calculation section is within a preset thickness tolerance range. The raising/lowering means lowers the arm from the uppermost position at high speed to a height position higher than the height position set in the height setting section by a predetermined distance. It is lowered at a low speed from a height position above the position by a predetermined distance to the height position set in the height setting section.
3. The grinding apparatus according to claim 1 or 2.

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