JP3602943B2 - Semiconductor wafer grinding machine - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a semiconductor wafer grinding apparatus for processing a surface of a semiconductor wafer such as performing a thickness processing using a grindstone, and particularly to a semiconductor wafer grinding apparatus having a feature in a stage for fixing the semiconductor wafer.
[0002]
[Prior art]
7 and 8 are views showing a stage and a work of a conventional semiconductor wafer grinding apparatus. The semiconductor wafer 1 is adhesively supported on an adhesive sheet 2 stretched over a ring 3. A work 4 including a semiconductor wafer 1, a ring 3, and an adhesive sheet 2 is mounted on a stage 5 having a flat surface. While the work 4 is mounted on the stage 5, the semiconductor wafer 1 is ground by bringing a grindstone into contact with the stage 5 from a direction facing the stage 5. At this time, the semiconductor wafer 1 is suctioned via the adhesive sheet 2 by suctioning from the suction unit 6 provided on the stage 5.
[0003]
By providing the suction unit 6 having substantially the same area as that of the semiconductor wafer 1 or by using the ring 3 having an inner diameter substantially equal to the outer diameter of the semiconductor wafer 1, the suction unit 6 is preferably used by the semiconductor wafer 1. It can be covered. By covering most of the suction part 6 with the semiconductor wafer 1, a leak that air flows in from the gap is suppressed, and the semiconductor wafer 1 is securely fixed.
[0004]
[Problems to be solved by the invention]
When the work 4 is placed on the flat stage 5 as shown in FIG. 8, a grinding wheel for grinding may come into contact with the ring 3. That is, in the case of a relatively large grindstone, the grindstone only contacts the semiconductor wafer 1 from the direction facing the stage 5 and also contacts the ring 3. Also, even a relatively small grindstone contacts the ring 3 when it makes a large movement to apply friction. When the grindstone comes into contact with the ring 3, the semiconductor wafer 1 to be actually ground may not be ground, and the ring 3 hinders the grinding. In that case, it is difficult to accurately process the thickness of the semiconductor wafer 1.
[0005]
As shown in FIG. 9, when the semiconductor wafer 1 a having a different shape and a smaller area from the semiconductor wafer 1 is used for the adhesive sheet 2, the ring 3, and the stage 5 as in FIG. Leakage from the gap between the wafers 1 causes an increase in the amount of air that flows in, thereby reducing the attraction force. If the attraction force is not sufficient, the semiconductor wafer 1a at the time of grinding is not stably fixed on the stage 5, and accurate thickness processing becomes difficult.
[0006]
An object of the present invention is to provide a semiconductor wafer grinding apparatus capable of realizing accurate thickness processing by firmly fixing a semiconductor wafer having a different size and shape to a stage without a grinding stone coming into contact with a frame.
[0007]
[Means for Solving the Problems]
The present invention is a grinding wheel for grinding the surface of a semiconductor wafer,
A stretchable sheet on which the semiconductor wafer is placed, and a wafer holding member including a ring-shaped frame over which the sheet is stretched;
A peripheral stage portion for mounting a frame, and a central stage portion formed of a porous ceramic having a trapezoidal cross-section and an upper base higher than the mounting surface of the peripheral stage portion, which is disposed opposite to the grinding stone; and a stage made of,
The peripheral stage section is provided with a plurality of suction holes for individually sucking and fixing a frame, and is a semiconductor wafer grinding apparatus, wherein:
[0008]
According to the present invention, since the central stage is closer to the grindstone than the peripheral stage, when the frame is to be mounted on the peripheral stage, the sheet is pushed out toward the grindstone by the central stage and stretched. Since the semiconductor wafer supported by the sheet is located at the top and bottom of the central stage, it is closer to the grindstone than the frame, preventing the grinding stone from contacting not only the semiconductor wafer but also the frame during grinding. , And accurate thickness processing is possible.
[0009]
Further, the central stage portion is made of porous ceramic, and is capable of supporting and adsorbing the adhesive sheet and the semiconductor wafer on the surface of the central stage portion by suction.
[0010]
Further, since the peripheral stage uses the suction holes to suck only the frame, the frame is firmly fixed. At this time, the semiconductor wafer connected to the frame via the sheet is firmly fixed to the frame by stretching the sheet. Therefore, the semiconductor wafer is firmly fixed to the peripheral stage and the central stage, and the accuracy of grinding can be improved. Also, the semiconductor wafers having different sizes and shapes can be firmly fixed to the center stage because the frames are firmly fixed.
[0011]
Further, the present invention is characterized in that an elastic member made of an elastic material and having a plurality of through holes formed over the entire surface is provided on the central stage portion.
[0012]
According to the present invention, the surface facing the ground surface of the semiconductor wafer comes into contact with the elastic member via the sheet. Therefore, even if there is an impact during the grinding, the surface is not damaged and the surface can be protected. In particular, when grinding is performed after forming an electrode pattern on the surface facing the ground surface of the semiconductor wafer, malfunction of the semiconductor chip due to damage to the electrode pattern can be prevented, or the yield of semiconductor wafer processing can be reduced. Can be improved.
Further, a plurality of through-holes are formed in the elastic member 41 over the entire surface, thereby preventing the suction of the semiconductor wafer via the porous ceramic from being hindered.
[0013]
BEST MODE FOR CARRYING OUT THE INVENTION
FIG. 1 is a sectional view showing a grinding device according to one embodiment of the present invention. The grinding device 10 includes a grindstone 11, a stage 16, and a wafer holding member 17, and is a device for grinding the surface of the semiconductor wafer 20. The semiconductor wafer 20 is placed on the wafer holding member 17, further placed on the stage 16, and ground by the grindstone 11.
[0014]
The grindstone 11 can be linearly displaced in the direction of the rotation axis while rotating, and the displacement can be adjusted according to the thickness of the semiconductor wafer before and after grinding or according to the progress of grinding. The grindstone 11 is made up of a plurality of concentric rings having different inner and outer diameters, and prevents grinding waste and the like from accumulating on the ground surface.
[0015]
At a position facing the grindstone 11, a stage 16 composed of a central stage 14 and a peripheral stage 15 is arranged. The peripheral stage 15 has a cylindrical shape as a whole, and its upper end forms an annular plane corresponding to the ring 13 for mounting the ring 13 thereon. The central stage section 14 is surrounded by the peripheral stage section 15 and has a columnar shape. The stage 16 rotates in the same direction as the rotation direction of the grindstone 11. Further, the rotation axis L2 of the stage 16 is parallel to the rotation axis L1 of the grindstone 11 and is separated by a predetermined distance. Therefore, while the semiconductor wafer 20 and the grinding stone 11 are in contact with each other, the direction of the relative speed is constantly changed, and the semiconductor wafer 20 is subjected to friction in all directions by the grinding stone 11. Thus, since the direction of friction is not biased, the surface of the semiconductor wafer 20 can be ground uniformly.
[0016]
FIG. 2 is a plan view showing a work used in the grinding device of FIG. Hereinafter, the work 21 is formed by integrating the semiconductor wafer 20 with the wafer holding member 17 including the ring 13 and the adhesive sheet 12 shown in FIG. The ring 13 is made of a material such as SUS304, for example, and has a thickness of about 1 mm, an outer diameter of 150 mm, and an inner diameter of 130 mm. The adhesive sheet 12 is a stretchable sheet, and has an adhesive material applied on one side to support the semiconductor wafer 20. For example, the thickness of the adhesive sheet 12 is 130 μm, and the adhesive strength is 300 g / 25 mm. The adhesive sheet 12 further adheres the semiconductor wafer 20 to the adhesive surface 22 while being stretched over the ring 13.
[0017]
3A and 3B are cross-sectional views showing how the work 21 is mounted on the stage 16, wherein FIG. 3A shows a state before mounting and FIG. 3B shows a state after mounting. In order to mount the work 21 on the stage 16, the ring 13 is mounted on the peripheral stage 15. The peripheral stage 15 is provided with an intake hole 31 that opens only on the mounting surface, and the ring 13 that closes the intake hole 31 is adsorbed on the surface of the peripheral stage 15.
[0018]
The central stage section 14 is raised higher than the peripheral stage section 15, and has a trapezoidal cross-sectional shape. Therefore, when the ring 13 is to be mounted on the peripheral stage 15, the adhesive sheet 12 in contact with the central stage 14 is stretched toward the grindstone 11. When the mounting of the ring 13 on the peripheral stage 15 is completed, the semiconductor wafer 20 is placed on the upper bottom 32 of the central stage 14 via the adhesive sheet 12. When the thickness of the ring 13 is about 1 mm, the upper bottom part 32 may be higher than the surface of the peripheral stage part 15 by about 2 to 3 mm.
[0019]
The central stage section 14 is made of porous ceramic, and is sucked. As described above, by using the porous ceramic, the adhesive sheet 12 and the semiconductor wafer 20 can be supported and adsorbed on the surface of the central stage 14 at the same time.
[0020]
FIG. 4 is a step diagram showing a step of grinding the semiconductor wafer by the grinding apparatus of FIG. 1, and FIG. 5 is a sectional view showing the step of the grinding step. First, in step s1 and FIG. 5A, the adhesive surface of the adhesive sheet 12 stretched over the ring 13 is adhered with the ground surface of the semiconductor wafer 20 turned upside down. This adhesion allows the semiconductor wafer 20 to be supported by the adhesive sheet 12 and at the same time protects the back surface unrelated to the grinding of the semiconductor wafer 20.
[0021]
Next, in step s2 and FIG. 5B, the ring 13 is mounted on the peripheral stage 15. When the semiconductor wafer 20 is mounted, the semiconductor wafer 20 is disposed on the upper bottom 32 of the central stage 14 via the adhesive sheet 12. In this state, grinding is performed by rotating the grindstone 11 and the stage 16 while sliding the grindstone 11 in the direction of the rotation axis to contact the semiconductor wafer 20.
[0022]
After the semiconductor wafer 20 has been processed to a predetermined thickness, the work 21 is removed from the stage 16 in step s3, the ground surface of the semiconductor wafer 20 is cleaned together with the work 21, and the ground surface is further processed by etching. . Finally, in step s4 and FIG. 5C, the semiconductor wafer 20 is peeled off from the adhesive sheet 12 of the work 21, and the grinding is completed.
[0023]
FIG. 6 is a cross-sectional view showing a stage and a work of a grinding device according to another embodiment of the present invention. An elastic member 41 made of an elastic material is provided on the upper bottom 32 of the central stage 14 in FIG. The elastic member 41 has a thickness of, for example, about several mm. Therefore, since the semiconductor wafer 20 is arranged on the central stage section 14 via the elastic member 41 together with the adhesive sheet 12 and ground, the semiconductor wafer 20 does not damage the surface facing the ground surface due to the impact of the grinding.
[0024]
Further, a plurality of through holes 42 are formed in the elastic member 41 over the entire surface. The through holes 42 serve as ventilation holes up to the surface of the central stage portion 14, and the semiconductor wafer is drawn by suction from the porous ceramic. 20 is not prevented from being absorbed. The diameter of the through hole 42 is, for example, about 1 mm.
[0025]
As described above, when the ring 13 is mounted on the peripheral stage 15, the adhesive sheet 12 is stretched in contact with the central stage 14, and the semiconductor wafer 20 is arranged at a position closer to the grindstone 11 than the ring 13. Grinding can be performed without the grinding stone 11 contacting the semiconductor wafer 20 without contacting the semiconductor wafer 20.
[0026]
Further, since the peripheral stage 15 sucks only the ring 13 by the suction hole 31, the ring 13 is firmly fixed to the peripheral stage 15.
[0027]
Further, the surface of the semiconductor wafer 20 facing the ground surface comes into contact with the elastic member 41 via the adhesive sheet 12, so that the surface is not damaged.
[0028]
【The invention's effect】
As described above, according to the present invention, it is possible to avoid a situation in which the grinding stone contacts not only the semiconductor wafer but also the frame during the grinding, and the grinding can be easily performed.
[0029]
Moreover, the adhesive sheet and the semiconductor wafer are supported and adsorbed by the central stage, and only the frame is adsorbed by the peripheral stage. In this manner , the semiconductor wafer itself can be firmly fixed to the central stage, and the precision of the grinding can be improved.
[0030]
Further, according to the present invention, by providing the elastic member having the through-hole on the central stage portion, it is possible to protect the surface facing the ground surface of the semiconductor wafer without hindering the suction of the semiconductor wafer.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view illustrating a grinding device according to an embodiment of the present invention.
FIG. 2 is a plan view showing the work of FIG. 1;
FIG. 3 is a cross-sectional view showing how the work of FIG. 2 is mounted on a stage.
FIG. 4 is a process chart showing a step of a grinding process by the grinding device of FIG. 1;
FIG. 5 is a sectional view showing a step of a grinding process by the grinding device of FIG. 1;
FIG. 6 is a cross-sectional view showing a stage and a work of a grinding device according to another embodiment of the present invention.
FIG. 7 is a plan view showing a work used in a conventional semiconductor wafer grinding apparatus.
FIG. 8 is a sectional view showing a stage and a work of a conventional semiconductor wafer grinding apparatus.
FIG. 9 is a plan view showing a work used in a conventional semiconductor wafer grinding apparatus.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Grinding apparatus 11 Grinding stone 12 Adhesive sheet 13 Ring 14 Central stage 15 Peripheral stage 16 Stage 17 Wafer holding member 20 Semiconductor wafer 41 Elastic member

Claims (2)

A grinding wheel for grinding the surface of a semiconductor wafer;
A stretchable sheet on which the semiconductor wafer is placed, and a wafer holding member including a ring-shaped frame over which the sheet is stretched;
A peripheral stage portion for mounting a frame, and a central stage portion having a trapezoidal cross-sectional shape and having an upper base made of porous ceramic higher than the mounting surface of the peripheral stage portion; and a stage made of,
A semiconductor wafer grinding apparatus , wherein the peripheral stage is provided with a plurality of intake holes for individually sucking and fixing a frame . 2. The apparatus for grinding a semiconductor wafer according to claim 1, further comprising an elastic member made of an elastic material having a plurality of through holes formed over the entire surface of the central stage.

Images