JP2009154246A - Method of adjusting attracting portion for attracting wafer thereto - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of adjusting an attracting portion that can flatten a grinding surface after grinding a wafer. <P>SOLUTION: In the method of adjusting the attracting portion of the grinding device composed of the attracting portion (26) for attracting the wafer (40), a vacuum means (36) for generating an attracting force on the attracting portion, and a grinding means (28A) for grinding the wafer attracted to the attracting portion, the vacuum means is driven to supply a blocking material to the attracting portion, and thus the attracting portion is blocked with the blocking material, followed by grinding the attracting portion with the grinding means. Instead of supplying the blocking material, grinding chips generated by preliminarily grinding the attracting portion may be used. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method for adjusting a suction unit that sucks a wafer. Specifically, the present invention provides a grinding apparatus including an adsorption unit that adsorbs a wafer, a vacuum unit that generates an attractive force in the adsorption unit, and a grinding unit that grinds the wafer adsorbed on the adsorption unit. It is related with the adjustment method of the adsorption | suction part.

  In the semiconductor manufacturing field, wafers tend to increase in size year by year, and wafers are becoming thinner to increase mounting density. In order to thin the wafer, so-called back grinding is performed to grind the back surface of the semiconductor wafer. For example, Patent Document 1 discloses a technique for grinding a back surface of a wafer by attracting and holding the wafer on a chuck using a vacuum suction force.

Usually, before the wafer is ground, the suction portion of the table, which is usually made of a porous material, is self-ground by a grinding wheel of a back grinding device. By self-grinding, the suction part is adjusted to be parallel to the bottom surface of the grinding wheel. FIG. 6A to FIG. 6D are diagrams for explaining a table adjustment method in the prior art. As shown in FIG. 6A, before the wafer is ground, the upper surface of the adsorption portion 260 of the table is not parallel to the lower surface of the grinding wheel 280 but slightly deviated. Next, when the suction unit 260 and the grinding wheel 280 of the table are rotated in opposite directions, the suction unit 260 is ground by the grinding wheel 280, and the upper surface of the suction unit 260 is parallel to the lower surface of the grinding wheel 280 (see FIG. (See 6 (b)). Thereby, adjustment of adsorption part 260 is completed.
JP 2000-21951 A

  Next, in order to grind the back surface 44 of the wafer 40 with the grinding wheel 280, the vacuum means 360 is operated to attract the wafer 40 to the suction portion 260. However, when the vacuum means 360 is operated, the suction portion 260 is deformed more than before the operation, as shown in FIG.

  FIG. 7 is a diagram showing an example of the relationship between the deformation amount of the table and the vacuum pressure. In FIG. 7, the vertical axis represents the amount of deformation of the table, and the horizontal axis represents the vacuum pressure. A solid line X1 in FIG. 7 indicates the amount of deformation at the center of the suction part 260 of the table, and a solid line X2 indicates the amount of deformation at the outer peripheral part of the suction part 260.

  As indicated by the solid line X1 in FIG. 7, the deformation amount at the center of the suction portion 260 increases as the vacuum pressure decreases. Further, as can be seen from the solid line X2, the wafer 40 is similarly deformed at the outer peripheral portion of the wafer 40, but the deformation amount is smaller than the deformation amount at the center portion. Further, FIG. 8 is a diagram showing the relationship between the deformation amount of the table and the distance from the center of the table. As shown in FIG. 8, the amount of table deformation is greatest at the center of the table and gradually decreases toward the outer periphery.

  Therefore, as shown in FIG. 5C, when the vacuum unit 360 is activated and the suction part 260 is deformed, the wafer 40 is also deformed following the suction part 260. Since the bottom surface of the grinding wheel 280 is flat, the thickness of the wafer 40 after grinding becomes unevenly distributed. That is, as can be seen from FIG. 6D, the thickness at the outer peripheral portion of the wafer 40 is smaller than the thickness at the central portion.

  In order to flatten such a wafer 40, for example, it is necessary to change the angle of the grinding wheel 280 slightly while grinding only the central portion of the wafer 40 again. This operation is extremely complicated and also delays the manufacturing time. In particular, when a thin wafer is required, there is a possibility that the wafer 40 cannot be flattened even if grinding is performed again.

  Furthermore, in order to suck the wafers 40 having different dimensions, a table in which the two sucking portions 260 are arranged concentrically may be used. Since these suction parts are deformed in a complicated manner when a suction force is applied, the thickness distribution of the wafer 40 after grinding becomes more complicated and its correction becomes more difficult.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a method for adjusting a suction portion that can flatten a ground surface after grinding of a wafer.

  In order to achieve the above-mentioned object, according to the first invention, a suction part for sucking a wafer, a vacuum means for generating a suction force on the suction part, and grinding for grinding the wafer sucked on the suction part In the adjusting method of adjusting the suction part of the grinding apparatus comprising means for driving, the vacuum means is driven to supply a clogging material to the suction part, thereby clogging the suction part with the clogging material And an adjustment method is provided in which the suction portion is ground by the grinding means.

  That is, in the first invention, the suction part is sucked and deformed by the vacuum means in a state of being clogged by the clogging material. Since the suction part is ground in a deformed state, the upper surface of the suction part becomes flat during suction. When the wafer is adsorbed by the adsorbing part, the upper surface of the adsorbing part becomes flat, so that the wafer itself is not deformed. Therefore, the ground surface of the wafer after grinding the wafer can be kept flat. The clogging material is, for example, an emulsion liquid or slurry.

  According to a second aspect of the present invention, there is provided a grinding apparatus comprising: a suction unit that sucks a wafer; a vacuum unit that generates a suction force in the suction unit; and a grinding unit that grinds the wafer sucked by the suction unit. In the adjustment method for adjusting the suction portion, the vacuum means is driven, the suction portion is pre-ground by the grinding means, and thereby the suction portion is clogged by grinding powder generated by the preliminary grinding, An adjustment method is provided in which the suction portion is further ground by a grinding means.

  That is, in the second invention, the suction part is sucked and deformed by the vacuum means in a state of being clogged with the grinding dust generated by the preliminary grinding. Since the suction part is ground in a deformed state, the upper surface of the suction part becomes flat during suction. When the wafer is adsorbed by the adsorbing part, the upper surface of the adsorbing part becomes flat, so that the wafer itself is not deformed. Therefore, the ground surface of the wafer after grinding the wafer can be kept flat.

According to a third aspect, in the second aspect, the suction pressure of the vacuum means when pre-grinding is made smaller than the suction pressure of the vacuum means after the suction portion is clogged.
That is, in the third aspect, the suction part can be clogged in a shorter time.

According to a fourth invention, in the first or second invention, the suction pressure of the vacuum means when grinding the suction portion is the suction pressure of the vacuum means when the wafer is sucked by the suction portion. To be the same.
That is, in the fourth aspect, even when the wafer is ground, the suction portion can be deformed to the same extent as when the suction portion is ground. For this reason, the upper surface of the adsorption part at the time of grinding of a wafer can be made flat.

Embodiments of the present invention will be described below with reference to the accompanying drawings. In the following drawings, the same members are denoted by the same reference numerals. In order to facilitate understanding, the scales of these drawings are appropriately changed.
FIG. 1 is a schematic plan view of a wafer processing apparatus to which the present invention can be applied. The wafer processing apparatus 10 mainly includes a back surface grinding unit 12 for grinding the back surface of the wafer and a dicing tape attaching unit 14 for attaching a dicing tape to the wafer 40. Each of these units is controlled by a control device (not shown). The wafer 40 processed by the dicing tape attaching unit 14 is transferred to the dicing unit 16 schematically shown and diced.

  The back grinding unit 12 is provided with wafer cassettes 20 </ b> A and 20 </ b> B that store a plurality of wafers 40. The wafers 40 are taken out from the wafer cassettes 20A and 20B one by one by the robot arms 22A and 22B. Next, the wafer 40 is sucked and held on the table 29 of the rotary stage 24 with its back surface 42 facing upward. A plurality of circuit patterns (not shown) are already formed on the surface 41 of the wafer 40, and a surface protection film 11 for protecting the circuit patterns is attached to the wafer surface.

  Next, the back surface of the wafer 40 is ground while the grinding portions 28A and 28B of the back surface grinding unit 12 such as a grinding wheel rotate. By grinding the back surface, the thickness of the wafer 40 is reduced to a desired thickness, for example, 50 micrometers.

  When the back surface grinding of the wafer 40 is completed, the wafer 40 is transferred from the back surface grinding unit 12 to the dicing tape attaching unit 14 by the robot arm 30, and the dicing tape 32 is attached to the back surface of the wafer 40 by a known method. Next, the surface protective film affixed to the surface of the wafer 40 is peeled off by a known method, and then the wafer 40 is conveyed to the dicing unit 16 and diced to a predetermined size.

  As shown in FIG. 1, the back surface grinding unit 12 includes a cleaning unit 27 that supplies a cleaning fluid to the ground wafer 40 and the like to clean the wafer. The cleaning means 27 can also clean the suction part 26. Further, the clogging material supply means 25 provided adjacent to the cleaning means 27 supplies the clogging material to the adsorption unit 26. The clogging material is a fluid containing particles that can clog the porous material forming the adsorbing portion 26. Such a fluid can be, for example, a slurry or an emulsion.

  FIG. 2 is a cross-sectional view of one of the suction portions 26 provided on the rotary stage 24 of the back grinding unit 12 as seen from the lateral direction. The table 29 mainly includes a cup-shaped base 21 and a suction portion 26 embedded in the upper surface of the base 21. As can be seen from FIG. 2, the upper surface of the suction portion 26 is flush with the upper surface of the outer peripheral portion of the base 21. It is assumed that the outer diameter of the base 21 is larger than the diameter of the wafer 40, and the outer diameter of the suction portion 26 is smaller than the diameter of the wafer 40. As shown in the figure, the table 29 rotates around the rotation axis 34 in the determination direction with respect to the grinding portion 28A.

  The adsorbing part 26 is made of a porous material, for example, porous alumina, and the base 21 is made of, for example, dense alumina. As shown in the figure, a vacuum means 36 such as a vacuum pump is connected to an internal space 48 of the base 21 through a conduit 37. Since the lower surface of the suction portion 26 is exposed in the internal space 48, when the vacuum means 36 is driven, a suction force is generated on the upper surface of the suction portion 26.

  FIG. 3A is a flowchart showing a method for adjusting the suction portion according to the first embodiment of the present invention. FIGS. 4A to 4D are views for explaining a method of adjusting the suction portion based on the first embodiment of the present invention. Hereinafter, with reference to these drawings, a method for adjusting the suction portion according to the first embodiment of the present invention will be described. For the sake of brevity, FIGS. 4 (a) to 4 (d) show only the suction portion 26 of the table 29 and omit the illustration of the surface protection film 11. .

  First, in step 101 of FIG. 3A, the vacuum means 36 is activated, thereby causing a suction force to act on the upper surface of the suction portion 26. Next, in step 102, the clogging material is supplied from the clogging material supply means 25 to the entire upper surface of the suction unit 26. The clogging material is sucked into the suction portion 26 by the suction action. For this reason, the adsorption | suction part 26 comes to be clogged with the clogging material. Since the pipe line 37 is disposed substantially at the center of the suction portion 26, when a suction force is applied in a clogged state, the central portion 26a of the suction portion 26 is deformed so as to be recessed from the outer peripheral portion 26b.

  Thereafter, in step 103, as shown in FIG. 4A, the table 29 including the suction portion 26 and the grinding portion 28A are rotated in opposite directions. Thereby, the upper surface of the adsorption | suction part 26 is self-ground. At this time, it should be noted that the upper surface of the outer peripheral portion of the base 21 is actually ground slightly. As shown in FIG. 4B, by self-grinding, the upper surface of the suction portion 26 is flat and parallel to the lower surface of the grinding portion 28A. Thereafter, the vacuum means 36 is stopped to end the suction action (step 104).

  FIG. 4C is a schematic diagram showing a cross section of the suction portion after completion of self-grinding. As shown in FIG. 4C, when the self-grinding is finished and the vacuum means 36 is stopped, the deformation of the suction portion 26 is released. At this time, as for the upper surface of the adsorption | suction part 26, the center part 26a protrudes rather than the outer peripheral part 26b like a part of spherical body.

  Thereafter, in step 105, the suction unit 26 is cleaned by the cleaning unit 27. As a result, the clogging material that has clogged the adsorbing portion 26 is washed away by the cleaning fluid. When all the clogging material has flowed out of the suction portion 26, the cleaning of the table 29 is completed.

  Next, in step 106, the wafer 40 is placed on the suction unit 26 of the table 29. Here, the wafer 40 is disposed such that the surface protection film 11 attached to the surface 41 is directly sucked by the suction portion 26. Next, in step 107, the vacuum means 36 is activated to attract the wafer 40 to the suction portion 26.

  The suction pressure of the vacuum means 36 when adsorbing the wafer 40 is preferably the same as the suction pressure during self-grinding. In such a case, since the suction part 26 is deformed in the same manner as during self-grinding, the upper surface of the suction part 26 becomes flat. Therefore, the wafer 40 adsorbed by the adsorbing portion 26 is hardly deformed, and the flatness can be maintained.

  Thereafter, in step 108, the back surface 42 of the wafer 40 is ground by the grinding portion 28A (see FIG. 4D). Then, when the wafer 40 has a desired thickness, for example, 50 micrometers, the grinding is finished. Next, in step 109, the suction action of the vacuum means 36 is stopped, and the wafer 40 is taken out by the robot arm 30. Thereafter, the table 29 is cleaned again by the cleaning means 27.

  Thus, in the present invention, since the suction part 26 is deformed when the suction part 26 is self-ground, the upper surface of the suction part 26 at the time of suction can be flattened. Accordingly, when the wafer 40 is attracted to the attracting portion 26, the upper surface of the attracting portion 26 becomes flat, so that the wafer 40 itself is not deformed. For this reason, the wafer 40 ground in the present invention is generally flat, and the variation in thickness is extremely small. Therefore, in the present invention, it is not necessary to perform grinding again in order to flatten the entire wafer 40. This will prove particularly advantageous when the wafer thickness after grinding is small.

  FIG. 3B is a flowchart showing a method for adjusting the suction portion according to the second embodiment of the present invention. Of steps 101 to 109 shown in FIG. 3B, steps 101 and 103 to 109 are the same as those described above with reference to FIG.

  In step 101 shown in FIG. 3B, the vacuum means 36 is activated, and then in step 102, the upper surface of the suction portion 26 is slightly ground by the grinding portion 28A (preliminary grinding). Preliminary grinding differs from self-grinding only in that it aims to generate grinding scraps.

  Grinding waste generated by the pre-grinding is sucked by the suction portion 26 and clogs the suction portion 26. Next, self-grinding is performed in the same manner as described above. Thereby, the upper surface of the suction portion 26 can be deformed flat during suction. Therefore, it will be apparent that the same effect as described above can be obtained in the second embodiment.

  Alternatively, preliminary grinding may be performed without starting the vacuum means 36, and the vacuum means 36 may be started after the preliminary grinding so that a suction action is generated. In this case, since the pre-grinding is performed in a state where the suction portion 26 is not deformed, it is possible to obtain grinding scraps necessary for clogging the suction portion 26 in a shorter time.

  Or you may make the suction pressure of the vacuum means 36 at the time of preliminary grinding smaller than the suction pressure of the vacuum means 36 at the time of grinding of the wafer 40. In this case, it will be understood that the grinding waste quickly flows into the suction portion 26, and therefore the suction portion 26 can be clogged in a shorter time.

  FIG. 5 is a side sectional view of another table used in the wafer processing apparatus. In another table 29 ′ shown in FIG. 5, another ring-shaped suction part 26 ′ is arranged around the suction part 26 and is connected to a common vacuum means 36 by a pipe line 37 ′. These adsorption portions 26, 26 'are embedded in the base 21'. Such another suction portion 26 ′ is used to suck a larger (large diameter) wafer 40 ′.

  Since the table 29 ′ includes the suction portion 26 ′, the suction portions 26 and 26 ′ are deformed more complicated than the suction portion 26 shown in FIG. 2 when the table 29 ′ is sucked. However, even when such a table 29 ′ is used, the adjustment method shown in FIGS. 3A and 3B is applied, and the upper surfaces of the suction portions 26 and 26 ′ at the time of suction are flattened. You can see that Even such a case is included in the scope of the present invention.

1 is a schematic plan view of a wafer processing apparatus to which the present invention can be applied. It is sectional drawing which looked at one of the adsorption | suction parts provided in the rotation stage of the back surface grinding unit from the horizontal direction. (A) It is a flowchart which shows the adjustment method of the adsorption | suction part based on 1st embodiment of this invention. (B) It is a flowchart which shows the adjustment method of the adsorption | suction part based on 2nd embodiment of this invention. (A)-(d) It is a figure for demonstrating the adjustment method of the adsorption | suction part based on 1st embodiment of this invention. It is a sectional side view of the other table used with a wafer processing apparatus. (A) It is a 1st figure for demonstrating the adjustment method of the table in a prior art. (B) It is a 2nd figure for demonstrating the adjustment method of the table in a prior art. (C) It is a 3rd figure for demonstrating the adjustment method of the table in a prior art. (D) It is the 4th figure for demonstrating the adjustment method of the table in a prior art. It is a figure which shows the example of the relationship between the deformation amount of a table, and a vacuum pressure. It is a figure which shows the relationship between the deformation amount of a table, and the distance from the center of a table.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Wafer processing apparatus 11 Surface protective film 12 Back surface grinding unit 14 Dicing tape sticking unit 16 Dicing unit 20A, 20B Wafer cassette 21, 21 'Base 22A, 22B Robot arm 24 Rotating stage 25 Clogging material supply means 26, 26' Adsorption part 26a Central part 26b Outer peripheral part 27 Cleaning means 28A, 28B Grinding part 29, 29 'Table 30 Robot arm 32 Dicing tape 34 Rotating axis 36 Vacuum means 37, 37' Pipe line 40, 40 'Wafer 41 Front face 42 Back face 48 Internal space

Claims (4)

An adjustment method for adjusting the suction portion of a grinding apparatus, comprising: a suction portion for sucking a wafer; a vacuum means for generating a suction force on the suction portion; and a grinding means for grinding the wafer sucked on the suction portion. In
Driving the vacuum means;
Supplying a clogging material to the adsorption part, thereby clogging the adsorption part with the clogging material;
An adjustment method in which the suction portion is ground by the grinding means. An adjustment method for adjusting the suction portion of a grinding apparatus, comprising: a suction portion for sucking a wafer; a vacuum means for generating a suction force on the suction portion; and a grinding means for grinding the wafer sucked on the suction portion. In
Driving the vacuum means;
Pre-grinding the suction part by the grinding means, thereby clogging the suction part by grinding powder generated by the preliminary grinding,
An adjustment method in which the suction portion is further ground by the grinding means.   The adjustment method according to claim 2, wherein the suction pressure of the vacuum means when the preliminary grinding is performed is smaller than the suction pressure of the vacuum means after the suction portion is clogged.   The adjustment according to claim 1 or 2, wherein the suction pressure of the vacuum means when grinding the suction portion is the same as the suction pressure of the vacuum means when the wafer is sucked to the suction portion. Method.

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