JP2008198709A - Cleaning device and holding table - Google Patents

Abstract

In various processing apparatuses, the workpiece is prevented from being damaged by preventing the workpiece from being charged with static electricity.
In a holding table 43 including a suction portion 43b for sucking a wafer W and a frame body 43a surrounding the suction portion 43b, the suction portion 43b is formed of porous ceramics mainly composed of zirconia, and the frame body. By forming 43a with a conductive member, the conductivity of the holding table 43 is increased, and static electricity is prevented from being charged on the wafer W.
[Selection] Figure 2

Description

  The present invention relates to a holding table for holding a wafer and a cleaning apparatus including the holding table.

  A wafer on which a plurality of devices such as ICs and LSIs are formed by dividing lines is divided into individual devices by a dividing apparatus such as a dicing apparatus.

  Thereafter, the wafer is transferred to a cleaning device having a rotatable holding table, and the holding table holding the wafer rotates at a rotation speed of about 1000 to 3000 RPM, and cleaning water such as pure water is applied to the rotating wafer. Is ejected to remove cutting waste. Further, after cleaning, high-pressure air is jetted onto the rotating wafer to remove the cleaning water (see, for example, Patent Document 1).

JP 2004-327613 A

  However, because the holding table is made of a material that is not highly conductive, such as alumina ceramics, when high-pressure cleaning water or high-pressure air is sprayed onto the wafer, static electricity is generated and the wafer is charged, causing dielectric breakdown. There is a problem that the devices constituting the wafer may be damaged.

  Further, not only the cleaning device but also a device using processing water or air at the time of processing may cause the same problem.

  Accordingly, the problem to be solved by the present invention is to prevent damage to the wafer by preventing static electricity from being charged to the wafer in various processing apparatuses.

  The first invention relates to a cleaning apparatus comprising at least a spinner table that holds and rotates a wafer, and a cleaning water supply means that supplies cleaning water to the wafer held by the spinner table. The suction table includes a suction table that sucks the wafer and a frame that surrounds the suction member, a drive source that rotates the holding table, and a suction source that applies a suction force to the suction unit. Is formed of porous ceramics mainly composed of zirconia, and the frame body is formed of a conductive member. The frame is made of stainless steel or zirconia.

  The second invention relates to a holding table for holding a wafer in various apparatuses, and is composed of a suction part for sucking the wafer and a frame surrounding the suction part, and the suction part is a porous ceramic mainly composed of zirconia. The frame body is formed of a conductive member. The frame is made of stainless steel or zirconia.

  In the present invention, the suction portion constituting the holding table is made of porous ceramics mainly composed of zirconia to improve conductivity, so that static electricity is less likely to be charged on the wafer, and dielectric breakdown does not occur on the wafer.

  In addition, porous ceramics mainly composed of zirconia have high toughness and low Vickers hardness. Therefore, when the holding surface is flattened, the holding surface becomes smooth and the damage to the wafer is reduced.

  Furthermore, if the suction part is made of porous ceramics mainly composed of zirconia and the frame is made of stainless steel or zirconia, the values of linear expansion coefficients of the suction part and the frame will be close to each other, so the familiarity of both will be good It becomes.

  A dicing apparatus 1 shown in FIG. 1 is an apparatus for cutting a wafer and dividing it into individual chips. A chuck table 2 for holding the wafer, and a cutting means 3 for cutting the wafer held on the chuck table 2. And a cleaning device 4 for cleaning the wafer after cutting.

  The wafer W to be cut is accommodated in the wafer cassette 5a in a state of being supported integrally with the frame F via the tape T. On the surface of the wafer W, a plurality of devices are formed by being divided into division lines. Hereinafter, the wafer W supported by the frame F via the tape T is simply referred to as a wafer W.

  The wafer cassette 5a is placed in the cassette placement area 5. In the vicinity of the wafer cassette 5a, a loading / unloading means 6 for unloading the wafer W from the wafer cassette 5a and loading the processed wafer W into the wafer cassette 5a is disposed. The carry-in / out means 6 is movable in the Y-axis direction with the frame F interposed therebetween. Between the carry-in / out means 6 and the wafer cassette 5a, a temporary placement region 7 is provided, which is a region in which the wafer W to be carried in / out is temporarily placed.

  On the front side of the dicing apparatus 1, there is disposed a chuck table 2 that holds the wafer W and is movable in the X-axis direction and is rotatable. Between the temporary placement region 7 and the chuck table 2, first transport means 8 for transporting the wafer W between the temporary placement region 7 and the chuck table 2 is disposed.

  Above the movement path of the chuck table 2 in the X-axis direction, an alignment unit 9 that detects a division planned line formed on the wafer is disposed. The alignment unit 9 includes an imaging unit 90 that captures an image of the wafer W, and detects a division-scheduled line by pattern matching between an image acquired by the imaging unit 90 and an image stored in advance. The image acquired by the imaging unit 90 can be displayed on the display unit 12.

  A cutting means 3 having a cutting blade 30 for cutting the wafer is disposed above the movement path of the chuck table 2 in the X-axis direction. The cutting means 3 is movable in the Y-axis direction and the Z-axis direction. A cutting blade 30 is attached to the tip of the spindle 31 disposed in the Y-axis direction, and the cutting blade 30 rotates as the spindle 31 rotates. It has a configuration.

  In the vicinity of the chuck table 2, a cleaning device 4 for cleaning the wafer W after cutting is disposed. Above the cleaning device 4, second transfer means 11 for transferring the wafer W between the chuck table 2 and the cleaning device 4 is disposed.

  As shown in FIG. 2, the cleaning device 4 includes a spinner table 40 that holds and rotates the wafer W, and a cleaning water nozzle 41 that is a cleaning water supply unit that supplies cleaning water to the wafer W held on the spinner table 40. And. Moreover, the air nozzle 42 which ejects the high pressure air for drying the wafer W after washing | cleaning is also provided.

  The spinner table 40 includes a holding table 43 that sucks and holds the wafer W, a suction source 44 that applies a suction force to the holding table 43, and a drive source 45 that rotates the holding table 43. The holding table 43 is connected to a drive source 45 and is configured to rotate by being driven by a motor inside the drive source 45. The drive source 45 can be raised and lowered by an air piston 46, and the holding table 43 is also raised and lowered as the drive source 45 is raised and lowered.

  The holding table 43 includes a suction part 43b that sucks the wafer W by a suction force from the suction source 44, and a frame body 43a that surrounds the suction part 43b. The suction part 43b is formed of porous zirconia porous. On the other hand, the frame body 43a may be formed of zirconia in the same manner as the suction portion 43b, or may be formed of another conductive member such as stainless steel.

The suction portion 43b is zirconia is formed of a porous ceramics mainly composed of zirconium oxide (zirconium dioxide), for example, zirconia yttrium oxide (Y 2 _{O 3)} was stabilized by the addition of stabilized zirconia particles (e.g. particle Zirconia porous is formed by sintering with a diameter of 50 μm) as 93% and a mixture of silicon dioxide and titanium oxide as 7%. The thus formed zirconia porous has a volume resistivity of 10 ⁶ to 10 ¹⁰ [Ω · cm], which is higher than that of an alumina porous having a volume resistivity of 10 ¹⁴ [Ω · cm] or more. High conductivity and static electricity is difficult to be charged.

  In addition, the conventionally used alumina porous has a bending strength of 350 [MPa] and a Vickers hardness of 15 [GPa], whereas the zirconia porous formed in the above manner is compared with the alumina porous. The toughness is as high as 1000 [MPa] and the Vickers strength is as low as 13 [GPa]. Therefore, when the suction surface of the suction part 43b is flattened by polishing or the like when the surface is flattened, it becomes a smooth surface in which minute flat surfaces are gathered, and the tip of the needle is gathered like the suction surface of alumina porous. Since it does not become a surface, damage to the held wafer is reduced, and occurrence of back surface chipping and back surface cracks when the back surface side of the wafer is held on the suction surface can be suppressed.

Furthermore, even when the frame body 43a is formed of stainless steel, the linear expansion coefficient of stainless steel is 10.4 × 10 ⁻⁶ / ° C., whereas the linear expansion coefficient of zirconia porous is 9.0 × 10 ⁻⁶ / ° C. The linear expansion coefficient of alumina porous is 6.0 × 10 ⁻⁶ / ° C., and the value of the linear expansion coefficient of zirconia porous is closer to that of stainless steel than alumina porous. Familiar with the formed frame 43a. Of course, when the frame 43a is formed of zirconia, the familiarity with the suction part 43b is further improved.

  Below the outer peripheral side of the holding table 43, a receiving portion 47 that receives used cleaning water and a discharge portion 48 that discharges the cleaning water staying in the receiving portion 47 are disposed.

  The wafer W accommodated in the wafer cassette 5a shown in FIG. 1 is unloaded to the temporary placement area 7 by the unloading / unloading means 6, and is transferred to and placed on the chuck table 2 by the first transfer means 8.

  Next, the chuck table 2 moves in the + X direction, the wafer W moves immediately below the alignment means 9, the surface of the wafer W is imaged by the imaging unit 90, a division line to be processed is detected, and the cutting blade 30. Are aligned in the Y-axis direction. Then, the chuck table 2 is further moved in the X-axis direction, and the cutting means 3 is lowered while the cutting blade 30 is rotated at a high speed, and the cutting blade 30 is cut into the detected division line. During the cutting, cutting water is ejected to the contact portion between the wafer W and the cutting blade 30.

  When the chuck table 2 is moved in the X-axis direction and cutting is performed while the cutting means 3 is indexed and fed in the Y-axis direction by an interval between adjacent divided lines, all the planned divided lines in the same direction are cut. The

  Further, when the chuck table 2 is rotated 90 degrees and then the same cutting is performed as above, all the division lines are cut vertically and horizontally and divided into individual devices.

  Even after being divided into devices in this manner, the individual devices remain adhered to the tape T, so that the shape of the wafer W is maintained as a whole. Then, the wafer W divided into devices is transferred to the cleaning device 4 while being supported by the frame F via the tape T by the second transfer means 11. As shown in FIG. 3, the wafer W is placed in a state where the holding table 43 is raised, and is sucked and held by the suction portion 43 b by the suction force supplied from the suction source 44.

  Next, as shown in FIG. 4, the holding table 43 is lowered and the tip of the cleaning water nozzle 41 is moved above the wafer W. Then, as shown in FIG. 5, the cleaning water is jetted from the cleaning water nozzle 41 to the entire surface of the wafer W while rotating the holding table 43 at a rotational speed of 1000 to 3000 RPM and swinging the cleaning water nozzle 41. Then, the cutting waste adhering to the surface of the wafer W is removed by cutting. At this time, since the cleaning water is ejected at a high pressure, static electricity is likely to be generated between the cleaning water and the wafer W. However, the suction portion 43b constituting the holding table 43 is formed of zirconia porous material having high conductivity. Static electricity is difficult to be charged, and dielectric breakdown does not occur in the devices constituting the wafer W.

  After the cleaning of the wafer W, the cleaning water nozzle 41 is retracted to the original position shown in FIG. 3, the tip of the air nozzle 42 is positioned above the wafer W, the holding table 43 is rotated, and the air nozzle 42 High pressure air is ejected from the wafer to remove the cleaning water adhering to the wafer. Thus, even when high-pressure air is ejected, static electricity is hardly generated due to the high conductivity of the suction portion 43b, and charging of the wafer can be prevented.

  The cleaned and dried wafer W is transferred to the temporary placement region 7 by the first transfer means 8 shown in FIG. And it is accommodated in the wafer cassette 5a by the loading / unloading means 6.

  In the above example, the example in which the holding table of the present invention is applied to the spinner table 40 of the cleaning apparatus 4 has been described. However, the present invention can also be applied to the chuck table 2 of the dicing apparatus 1, for example. The wafer held on the chuck table 2 may generate static electricity because cutting water is ejected at the time of cutting. However, if the suction part of the chuck table 2 is made of porous ceramics mainly composed of zirconia. It is possible to prevent static electricity from being charged on the wafer during cutting. Also, in other processing apparatuses, the present invention can be applied to a holding portion where static electricity is likely to be generated.

It is a perspective view which shows an example of a dicing apparatus. It is a perspective view which shows an example of a washing | cleaning apparatus. It is sectional drawing which shows schematically the state which mounts a wafer in the holding table of a washing | cleaning apparatus. It is sectional drawing which shows schematically the state before ejecting cleaning water to the wafer hold | maintained at the holding table. It is a perspective view which shows the state which ejects cleaning water to the wafer hold | maintained at the holding table.

Explanation of symbols

1: Dicing device 2: Chuck table 3: Cutting means 30: Cutting blade 31: Spindle 4: Cleaning device 40: Spinner table 41: Cleaning water nozzle 42: Air nozzle 43: Holding table 43a: Frame body 43b: Suction unit 44: Suction source 45: drive source 46: air piston 47: receiving portion 48: discharge portion 5: cassette placement area 5a: wafer cassette 6: carry-in / out means 7: temporary placement area 8: first transfer means 9: alignment means 90 : Imaging unit 11: Second transport unit 12: Display unit

Claims (4)

A cleaning apparatus comprising at least a spinner table capable of rotating while holding a wafer, and cleaning water supply means for supplying cleaning water to the wafer held on the spinner table,
The spinner table includes a holding table configured by a suction unit that sucks a wafer and a frame that surrounds the suction unit, a drive source that rotationally drives the holding table, and a suction that applies a suction force to the suction unit. Consisting of a source and
The suction unit is formed of porous ceramics mainly composed of zirconia, and the frame is formed of a conductive member.   The cleaning apparatus according to claim 1, wherein the frame is formed of stainless steel or zirconia. A holding table for holding a wafer,
A holding table comprising a suction part for sucking a wafer and a frame surrounding the suction part, wherein the suction part is formed of porous ceramics mainly composed of zirconia, and the frame is formed of a conductive member. .   The holding table according to claim 3, wherein the frame is formed of stainless steel or zirconia.

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