Method for processing frame units and method for processing wafers

Abstract

The present invention provides a method for processing a frame unit that can prevent variations in wafer thickness and wafer damage during wafer processing. [Solution] The frame unit processing method includes: an aperture center coordinate detection step of imaging the frame unit 2 with an imaging means and detecting the coordinates (X1, Y1) of the center C1 of the aperture 6a of the frame 6; a wafer center coordinate detection step of imaging the frame unit 2 with an imaging means and detecting the coordinates (X2, Y2) of the center C2 of the wafer 4 housed in the aperture 6a; and a determination step of comparing the coordinates (X1, Y1) of the center C1 of the aperture 6a of the frame 6 with the coordinates (X2, Y2) of the center C2 of the wafer 4 to determine whether the deviation r is within an acceptable value. In the determination step, if the deviation r is within an acceptable value, a processing step of processing the wafer 4 is performed, and if the deviation r exceeds an acceptable value, the frame unit 2 is remade.

Description

Technical Field

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[0001] The present invention relates to a method for processing a frame unit in which a wafer is accommodated in an opening of a frame having an opening for accommodating the wafer at the center, and the wafer and the frame are integrated by a tape.

Background Art

[0002] A wafer on which a plurality of devices such as ICs and LSIs are partitioned by a dicing line and formed on the surface is ground on the back surface by a grinding device to be thinned to a predetermined thickness, and then divided into individual device chips by a dicing device or a laser processing device. Each of the divided device chips is used in electrical devices such as mobile phones and personal computers.

[0003] In addition, since it becomes difficult to transport the wafer when the wafer is ground and thinned, a technique has been proposed in which the wafer is accommodated in an opening of a frame having an opening for accommodating the wafer at the center in advance, and a frame unit in which the wafer and the frame are integrated by a tape is configured (for example, see Patent Document 1).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, if the center of the opening of the frame and the center of the wafer deviate beyond the allowable value, the wafer cannot be ground uniformly, and problems such as variations in the thickness of the wafer or breakage of the wafer may occur.

[0006] The object of the present invention is to provide a method for processing a frame unit that can prevent variations in wafer thickness and prevent wafer damage when wafers are processed. [Means for solving the problem]

[0007] According to the present invention, the following method for processing frame units is provided that solves the above problems. That is, A method for processing a frame unit comprising a frame having an opening in the center for housing a wafer, the wafer being housed in the opening, and the wafer and the frame being integrated by tape, A process for detecting the center coordinates of the opening of the frame, which involves imaging the frame unit with an imaging means and detecting the center coordinates of the opening of the frame, A wafer center coordinate detection step involves imaging the frame unit with the imaging means and detecting the center coordinates of the wafer housed in the aperture. The process includes a determination step of comparing the center coordinates of the opening in the frame with the center coordinates of the wafer to determine whether the deviation is within an acceptable range, The provided method for processing a frame unit involves, in the determination step, performing a processing step to process the wafer if the deviation is within an acceptable value, and remaking the frame unit if the deviation exceeds an acceptable value.

[0008] Preferably, the wafer is thinned by grinding during the processing step. [Effects of the Invention]

[0009] The processing method for the frame unit of the present invention is: A method for processing a frame unit comprising a frame having an opening in the center for housing a wafer, the wafer being housed in the opening, and the wafer and the frame being integrated by tape, A process for detecting the center coordinates of the opening of the frame, which involves imaging the frame unit with an imaging means and detecting the center coordinates of the opening of the frame, A wafer center coordinate detection step involves imaging the frame unit with the imaging means and detecting the center coordinates of the wafer housed in the aperture. The process includes a determination step of comparing the center coordinates of the opening in the frame with the center coordinates of the wafer to determine whether the deviation is within an acceptable range, In this determination process, if the deviation is within the allowable value, a processing process is performed on the wafer; if the deviation exceeds the allowable value, the frame unit is remade. This prevents variations in wafer thickness and wafer damage when the wafer is processed. [Brief explanation of the drawing]

[0010] [Figure 1] (a) Exploded perspective view of the frame unit, (b) Perspective view of the frame unit. [Figure 2] A schematic diagram showing the state in which the frame unit shown in Figure 1 is being imaged by the imaging means. [Figure 3] A schematic diagram of a planar image of a frame unit captured by the imaging means shown in Figure 2. [Figure 4] Perspective view of the grinding machine. [Figure 5] A schematic diagram showing the processing steps (grinding process). [Modes for carrying out the invention]

[0011] Hereinafter, preferred embodiments of the frame unit processing method according to the present invention will be described with reference to the drawings.

[0012] (Frame Unit 2) The frame unit 2 shown in Figures 1(a) and 1(b) is an annular frame 6 having a circular opening 6a in the center for housing a disc-shaped wafer 4. The wafer 4 is housed in the opening 6a of the annular frame 6, and the wafer 4 and frame 6 are integrated by a circular tape 8. In the frame unit 2 of this embodiment, the surface 4a of the wafer 4 is attached to the tape 8, and the back surface 4b of the wafer 4 is exposed.

[0013] The wafer 4 may be formed from a semiconductor material such as silicon. The surface 4a of the wafer 4 is divided into a plurality of rectangular regions by grid-like division lines 10, and a device 12 such as an IC or LSI is formed in each of the plurality of rectangular regions. The frame 6 may be formed from an appropriate metal material or synthetic resin material. The tape 8 may be an adhesive tape or a thermocompression sheet. The thermocompression sheet is a sheet of thermoplastic synthetic resin (for example, a polyolefin resin) that softens or melts and exhibits adhesive force when heated to a temperature near its melting point.

[0014] (Aperture center coordinate detection process) In this embodiment, first, an aperture center coordinate detection step is performed in which the frame unit 2 is imaged by the imaging means and the center coordinates of the aperture 6a of the frame 6 are detected. In the aperture center coordinate detection step, as shown in Figure 2, the frame unit 2 is first placed on a suitable table 14. Next, the frame unit 2 is imaged from above by the imaging means 16 to obtain a planar image of the frame unit 2 (see Figure 3). Then, based on the acquired planar image of the frame unit 2, the coordinates of any three points on the periphery of the aperture 6a (for example, the three points indicated by the labels A1, A2, and A3 in Figure 3) are detected. Then, using the coordinates of the three detected points, the coordinates (X1, Y1) of the center C1 of the aperture 6a are calculated.

[0015] (Wafer center coordinate detection process) Further, a wafer center coordinate detection step is performed to image the frame unit 2 by an imaging means and detect the center coordinates of the wafer 4 accommodated in the opening 6a. The wafer center coordinate detection step may be performed before or after the opening center coordinate detection step. In the wafer center coordinate detection step, similar to the opening center coordinate detection step, first, the frame unit 2 is placed on the table 14. Next, the frame unit 2 is imaged from above by the imaging means 16 to obtain a planar image of the frame unit 2. Then, based on the obtained planar image of the frame unit 2, the coordinates of any three points on the outer periphery of the wafer 4 (for example, the three points indicated by reference numerals B1, B2, and B3 in FIG. 3) are detected. And using the coordinates of the three detected points, the coordinates (X2, Y2) of the center C2 of the wafer 4 are calculated.

[0016] In addition, when the opening center coordinate detection step is performed before the wafer center coordinate detection step, the planar image of the frame unit 2 obtained in the opening center coordinate detection step may be used in the wafer center coordinate detection step. Conversely, when the wafer center coordinate detection step is performed before the opening center coordinate detection step, the planar image of the frame unit 2 obtained in the wafer center coordinate detection step may be used in the opening center coordinate detection step.

[0017] (Judgment step) After performing the opening center coordinate detection step and the wafer center coordinate detection step, the coordinates (X1, Y1) of the center C1 of the opening 6a of the frame 6 and the coordinates (X2, Y2) of the center C2 of the wafer 4 are compared, and a judgment step is performed to judge whether the deviation between the center C1 and the center C2 is within the allowable value. In the judgment step, the deviation r (the distance from the center C1 to the center C2) between the coordinates (X1, Y1) of the center C1 and the coordinates (X2, Y2) of the center C2 is calculated. The deviation r can be calculated by the following formula.

[0018]

Equation

[0019] Then, it is determined whether the calculated deviation r is within the tolerance value (for example, 1 mm). If the deviation r is within the tolerance value, the following processing steps are performed on the wafer 4. On the other hand, if the deviation r exceeds the tolerance value, the wafer 4 is removed from the tape 8 and the frame unit 2 is remade.

[0020] (Processing process) If the deviation r is within the allowable value, a processing step to perform on the wafer 4 may be a grinding step to thin the wafer 4. The grinding step can be performed using a grinding apparatus 18, for example, as shown in Figure 4. The grinding apparatus 18 comprises a holding means 20 for holding the frame unit 2, a grinding means 22 for grinding the wafer 4 of the frame unit 2 held by the holding means 20, and a grinding feed means 24 for grinding feed the grinding means 22.

[0021] (Holding means 20 of grinding device 18) The holding means 20 is moved in the X-axis direction indicated by arrow X in Figure 4 by an X-axis feed means (not shown) which may be of the ball screw type, and is also rotated about the vertical axis by a motor (not shown). The holding means 20 also includes a wafer holding part 26 for holding the wafer 4 of the frame unit 2 and a frame holding part 28 for holding the frame 6 of the frame unit 2.

[0022] (Wafer holding portion 26 of holding means 20) The wafer holding section 26 has a circular suction chuck 30. The suction chuck 30 is made of a porous material such as porous ceramics. The suction chuck 30 is also connected to a suction means (not shown). The wafer holding section 26 uses the suction means to generate suction force on the upper surface of the suction chuck 30 to hold the wafer 4 in place.

[0023] (Frame holding portion 28 of the holding means 20) The frame holding portion 28 is formed in an annular shape and is located on the outer circumference of the suction chuck 30. Multiple suction holes 32 (four in this embodiment) are formed on the upper surface of the frame holding portion 28 at intervals in the circumferential direction. The suction holes 32 are connected to a suction means (not shown). The frame holding portion 28 holds the frame 6 by suction force generated in the suction holes 32 by the suction means. The upper surface of the frame holding portion 28 is lower than the upper surface of the wafer holding portion 26, so that the grinding wheel 50 of the grinding means 22 does not come into contact with the frame 6 when grinding the wafer 4.

[0024] (Grinding means 22 of grinding device 18) The grinding means 22 includes a lifting plate 36 that is vertically movable and supported by a support wall 34 provided at the end of the grinding device 18 (the far end in Figure 4), a protruding member 38 that protrudes from the lifting plate 36, a spindle 40 that is rotatably supported by the protruding member 38, and a spindle motor 42 that rotates the spindle 40. The spindle 40 is rotated by the spindle motor 42 about an axis that extends in the vertical direction. As shown in Figure 5, a disc-shaped wheel mount 44 is fixed to the lower end of the spindle 40. An annular grinding wheel 48 is fastened to the lower surface of the wheel mount 44 by bolts 46. Multiple grinding wheels 50 are fixed to the outer peripheral edge of the lower surface of the grinding wheel 48, arranged in an annular pattern at intervals in the circumferential direction.

[0025] (Grinding feed means 24 of grinding device 18) As shown in Figure 4, the grinding feed mechanism 24 includes a ball screw 52 extending vertically along one side of the support wall 34 and a motor 54 that rotates the ball screw 52. The nut portion (not shown) of the ball screw 52 is connected to the lifting plate 36. The grinding feed mechanism 24 converts the rotational motion of the motor 54 into linear motion using the ball screw 52 and transmits it to the lifting plate 36, thereby feeding the grinding mechanism 22 vertically along the guide rail 34a attached to the support wall 34.

[0026] In the processing (grinding) step, first, the frame unit 2 is held by the holding means 20. When holding the frame unit 2 by the holding means 20, the holding means 20 is first positioned at the attachment / detachment position shown in Figure 4. Next, the back surface 4b of the wafer 4 is turned upward, and the frame unit 2 is placed on the holding means 20. Then, a suction force is generated on the upper surface of the suction chuck 30 of the wafer holding part 26, and the wafer 4 of the frame unit 2 is held by suction. In addition, a suction force is generated in the suction hole 32 of the frame holding part 28, and the frame 6 of the frame unit 2 is held by suction.

[0027] Once the frame unit 2 is held by the holding means 20, the back surface 4b of the wafer 4 is ground by the grinding means 22. When grinding the back surface 4b of the wafer 4, first the holding means 20 is positioned at the grinding position shown in Figure 5. Next, the spindle 40 is rotated at a predetermined rotational speed (for example, 6000 rpm) in the direction indicated by arrow R1. Also, the holding means 20 is rotated at a predetermined rotational speed (for example, 300 rpm) in the direction indicated by arrow R2. Next, the spindle 40 is lowered by the grinding feed means 24, bringing the grinding wheel 50 into contact with the back surface 4b of the wafer 4, and grinding water is supplied to the part where the grinding wheel 50 is in contact with the back surface 4b. Then, by lowering the spindle 40 at a predetermined grinding feed rate (for example, 1.0 μm / s), the back surface 4b of the wafer 4 is ground with the grinding wheel 50. This makes it possible to thin the wafer 4 to a predetermined thickness.

[0028] As described above, in this embodiment, the wafer 4 is processed only when the deviation r between the coordinates (X1, Y1) of the center C1 of the opening 6a of the frame 6 and the coordinates (X2, Y2) of the center C2 of the wafer 4 is within the allowable value. This prevents variations in the thickness of the wafer 4 when it is processed, and also prevents damage to the wafer 4. [Explanation of symbols]

[0029] 2: Frame Unit 4: Wafer 4a: Wafer surface 4b: Back side of the wafer 6: Frame 6a: Frame opening 8: Tape 16: Imaging means C1: Center of the frame opening C2: Center of the wafer r: The difference between the center of the frame and the center of the wafer.

Claims

1. A method for processing a frame unit comprising a frame having an opening in the center for housing a wafer, the wafer being housed in the opening, and the wafer and the frame being integrated by tape, A process for detecting the center coordinates of the opening of the frame, which involves imaging the frame unit with an imaging means and detecting the center coordinates of the opening of the frame, A wafer center coordinate detection step involves imaging the frame unit with the imaging means and detecting the center coordinates of the wafer housed in the aperture. The process includes a determination step of comparing the center coordinates of the opening in the frame with the center coordinates of the wafer to determine whether the deviation is within an acceptable range, A method for processing a frame unit, wherein, in the determination step, if the deviation is within an acceptable value, a processing step is performed to process the wafer, and if the deviation exceeds an acceptable value, the frame unit is remade.

2. A method for processing a frame unit according to claim 1, wherein the wafer is thinned by grinding in the processing step.

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