TWI909039B - wafer spacing formation method - Google Patents

Abstract

[Problem] To achieve a satisfactory predetermined spacing between wafers. [Solution] The wafer spacing formation step reduces friction between the expander and the holding surface by ejecting air from the holding surface of the holding stage located below the expander. Therefore, the expander can be easily expanded, thus achieving a satisfactory predetermined spacing between wafers.

Description

wafer spacing formation method

This invention relates to a method for forming wafer spacing by expanding an expander to create a predetermined spacing between multiple wafers constituting a workpiece.

There is an existing process that attaches a wafer with a break point formed inside along a predetermined dicing line, or a wafer that has been divided into multiple chips along the predetermined dicing line, to an expander, and expands the expander to increase the chip spacing.

Furthermore, there is a process that attaches the aforementioned wafer to an expansion sheet, the expansion sheet having an adhesive layer called a die attach film, and expands the expansion sheet to increase the wafer spacing, and divides the die attach film according to the wafer.

A wafer expansion apparatus includes: a frame fixing part, a suction and holding stage, and an expansion drum disposed on the outer periphery of the suction and holding stage. By vertically raising the expansion drum, the wafer is expanded, thereby increasing the wafer spacing. Then, to maintain the expanded wafer spacing, the suction and holding stage holds the expanded wafer. [Preferred Art Documents] [Patent Documents]

[Patent Document 1] Japanese Patent No. 6741529 [Patent Document 2] Japanese Unexamined Patent No. 2007-123658

[Problem to be Solved by the Invention] However, in the aforementioned wafer expansion apparatus, when the expansion drum rises, the expansion drum and the suction holding stage are positioned on almost the same plane. Therefore, friction occurs between the central region of the wafer and the holding surface of the suction holding stage, making it difficult to adequately expand the central region of the wafer.

Therefore, the purpose of this invention is to provide a method for forming a wafer spacer that effectively forms a predetermined spacing between wafers.

[Technical Means for Solving the Problem] According to the present invention, a method for forming wafer spacers is provided, which forms predetermined spacers between a plurality of wafers constituting a workpiece, said workpiece being supported by an expansion lamination at an opening of a ring frame. The wafer spacer forming method comprises: a wafer spacer forming step in which, under conditions where air is ejected from the holding surface of a holding stage disposed below the expansion lamination to reduce friction between the expansion lamination and the holding surface, the wafer spacers are formed... The expansion wafer expands to form a predetermined gap between the wafers; and a shrinkage step, following the wafer gap formation step, involves heating a portion of the expansion wafer between the inner periphery of the annular frame and the outer periphery of the workpiece to shrink the wafer while the area corresponding to the wafer is held by the holding surface of the holding stage and the gap between the wafers is maintained.

[Invention Benefits] In this invention's wafer spacing formation method, during the wafer spacing formation step, air is ejected from the holding surface of a holding stage disposed below the expander wafer, thereby reducing friction between the expander wafer and the holding surface. Therefore, since the area corresponding to the wafer on the expander wafer can be easily expanded, a predetermined spacing can be well formed between the wafers.

In the wafer spacing method of this invention, a wafer 100 as shown in FIG1 is used as the workpiece. The wafer 100 has a circular shape and a grid-like dicing pre-line 103 is formed on its front side. Components 101 are formed in each area divided by the dicing pre-line 103.

In this embodiment, the wafer 100 is processed in the form of a frame unit 110. The frame unit 110 is formed by integrating an annular frame 111 with the wafer 100 using an expansion piece 113. The annular frame 111 has an opening 112 that can accommodate the wafer 100, and the wafer 100 is positioned within the opening 112 of the annular frame 111. Thus, in this embodiment, the wafer 100 is supported by the opening 112 of the annular frame 111 via the expansion piece 113.

Next, the steps of the wafer spacing method of this embodiment will be explained. This wafer spacing forming method is used to form a predetermined spacing between multiple wafers constituting a wafer 100.

[Modifier Layer Formation Step] In this step, as shown in Figure 2, a laser irradiator 200 is used to irradiate laser light 201 along the dicing pre-defined lines 103 of the wafer 100. This forms a weak-intensity modifier layer 202, acting as a breakage initiation point, inside the wafer 100 along the dicing pre-defined lines 103. As a result, the modifier layer 202 divides the wafer 100 into multiple wafers 120, each containing an element 101.

[Wafer Spacing Formation Step] In this step, a predetermined spacing is formed between the wafers 120 of the wafer 100 using the expansion piece 113 of the expansion frame unit 110.

In this step, the sheet expansion device 4 shown in Figures 3 and 4 is used. As shown in Figure 3, this sheet expansion step 4 has a rectangular base 40. A frame holding part 5 of the annular frame 111 of the holding frame unit 110 is provided on the upper surface of this base 40.

The frame retaining member 5 includes: a cylindrical base 51 disposed on the upper surface of the base 40; and four clamps 52 serving as frame fixing parts, disposed on the outer periphery of the upper end of the cylindrical base 51. The upper surface of the cylindrical base 51 functions as a mounting surface 511 for mounting the annular frame 111 of the frame unit 110. The annular frame 111, mounted on the mounting surface 511, is fixed to the cylindrical base 51 by means of the clamps 52. In this way, the frame retaining member 5 can hold the frame unit 110, which includes the annular frame 111 and the wafer 100.

Within the cylindrical base 51 of the frame holding member 5, a wafer expansion mechanism 6 is provided for expanding the expansion wafer 113 mounted on the annular frame 111. This wafer expansion mechanism 6 includes: a holding stage 62 for holding the wafer 100; an expansion drum 61 configured to hold the holding stage 62 from below; and a moving member 63 for moving the expansion drum 61 and the holding stage 62 along the Z-axis.

The holding stage 62 holds the wafer 100 held in the holding frame unit 110 of the frame holding member 5. The holding stage 62 has a circular plate-shaped body 621 and a holding surface (adsorption chuck) 622 disposed on the body 621. As shown in FIG4, the holding surface 622 is disposed on the upper surface of the body 621 in such a way as to cover the body ventilation path 623 disposed on the body 621.

The holding surface 622 is permeable, and by connecting to the suction source 637 shown in FIG. 4, it attracts and holds the area of the wafer 100 attached to the expansion sheet 113, namely the wafer attachment area 131 (see FIG. 1). That is, the holding stage 62 can attract and hold the wafer 100 through the expansion sheet 113 by means of the holding surface 622. Furthermore, the holding surface 622 is configured to eject a predetermined amount (e.g., a small amount) of air by means of the air source 638 shown in FIG. 4.

The retaining platform 62, configured as described above, is supported by the expanding drum 61. As shown in FIG3, the expanding drum 61 has an annular peripheral wall 611 and a circular bottom wall 612 covering the lower surface of the peripheral wall 611. A cavity 614 penetrating the bottom wall 612 is provided in the center of the bottom wall 612. Furthermore, a plurality of expanding auxiliary rollers 613 are arranged at the upper end of the peripheral wall 611. As shown in FIG4, the upper surface of the expanding auxiliary rollers 613 is positioned at approximately the same height as the retaining surface 622 of the retaining platform 62.

The main body 621 of the retaining platform 62 is covered around it almost without gaps by the peripheral wall 611 of the expanding drum 61 and is supported on the bottom wall 612 of the expanding drum 61.

The expansion drum 61 is supported by a moving member 63. The moving member 63 is a cylinder mechanism and includes: a piston base 630; a piston rod 631, which is configured to move relative to the piston base 630 in the Z-axis direction; and a circular support base 632, which is located at the upper end of the piston rod 631. The support base 632 supports the bottom wall 612 of the expansion drum 61 from below.

Therefore, in the moving component 63, by moving the piston rod 631 in the Z-axis direction, the expansion drum 61 and the holding platform 62 can be moved in the Z-axis direction.

A connecting pipe 635 is provided at the center of the support base 632. The connecting pipe 635 passes through the cavity 614 (see Figure 3) of the bottom wall 612 of the expansion drum 61 and the center of the body 621 of the retaining platform 62. In this way, the retaining platform 62 and the expansion drum 61 are supported by the support base 632 of the moving component 63 while being connected to the center by the same connecting pipe 635.

Furthermore, as shown in Figure 4, an air passage 636 is provided in the connecting pipe 635 and the piston rod 631. One end of this air passage 636 is connected to the holding surface 622 of the holding platform 62 through the connecting pipe 635 and the main body ventilation path 623 of the holding platform 62. Furthermore, the other end of the air passage 636 is connected to the air source 638 and the suction source 637 through the piston rod 631 and the switching valve 639.

That is, the retaining surface 622 of the retaining platform 62 is connected to the suction source 637 or the air source 638 through this air passage 636.

Furthermore, as shown in Figure 3, the sheet expansion device 4 includes a heating component 8, which is used to heat the expansion sheet 113 of the frame unit 110 held in the frame holding component 5.

The heating component 8 includes: an infrared heater 81; a support rod 82 supporting the infrared heater 81; and a rotating component 83 rotating the support rod 82. The infrared heater 81 is formed as an annular shape that substantially corresponds to the size of the contraction region 132 (see FIG. 1) in the expander 113. This contraction region 132 is the region between the wafer attachment region 131 in the expander 113 and the annular frame 111, that is, the portion of the expander 113 between the inner periphery of the annular frame 111 and the outer periphery of the wafer 100.

Rotate component 83 to rotate the infrared heater 81 between the retraction position (the position shown in Figure 3) and the heating position. The heating position is the position above the contraction area 132 in the expansion plate 113 of the frame unit 110 held by the frame retaining component 5.

Furthermore, the wafer expansion device 4 includes a control unit 17. The control unit 17 performs the wafer spacing formation step by controlling the operation of each component of the wafer expansion device 4.

The following describes the chip spacing formation steps using this chip expansion device 4.

In this step, as shown in Figure 5, for example, the operator places the annular frame 111 of the frame unit 110 on the placement surface 511 of the cylindrical base 51 in the frame retaining member 5, and fixes it to the cylindrical base 51 by means of the clamp 52 (frame retaining step).

At this time, the control unit 17 controls the moving component 63 to move the piston rod 631 to the lower side, thereby positioning the holding surface 622 of the holding platform 62 and the expansion auxiliary roller 613 of the expansion drum 61 below the expansion plate 113 of the frame unit 110, as shown in FIG. 5.

Furthermore, the control unit 17 controls the switching valve 639 to connect the holding surface 622 of the holding platform 62 to the air source 638 through the air passage 636. Thereby, as shown by arrow 301 in FIG5, air is ejected from the holding surface 622 of the holding platform 62 located below the expansion plate 113.

Next, with air already ejected from the holding surface 622, the control unit 17 controls the moving component 63 to move the piston rod 631 to the upper side, as indicated by arrow 401 in Figure 6. Thus, as shown in Figure 6, the control unit 17 raises the expansion drum 61 and the holding platform 62 to the predetermined expansion position by positioning the expansion auxiliary roller 613 of the expansion drum 61 and the holding surface 622 of the holding platform 62 above the mounting surface 511 of the cylindrical base 51.

In this way, the expansion auxiliary roller 613 of the expansion drum 61 abuts against the expansion wafer 113, pushing the expansion wafer 113 upward. Thus, the expansion wafer is expanded (wafer expansion step). As a result, tensile force acts radially on the wafer 100 attached to the expansion wafer 113. Because of this radial tensile force acting on the wafer 100, the wafer 100 breaks along the modified layer 202 formed along the predetermined dicing line 103 and is separated into individual wafers 120, forming a predetermined spacing between adjacent wafers 120.

Furthermore, in this expansion step, the holding surface 622 of the holding stage 62, which is positioned at approximately the same height as the upper surface of the expansion auxiliary roller 613, also contacts the expansion sheet 133. Regarding this, in this embodiment, air is ejected from the holding surface 622 to reduce friction between the expansion sheet 113 and the holding surface 622. Therefore, since the effects of friction with the holding surface 622 can be suppressed while the expansion sheet is easily expanded, a predetermined spacing can be well formed between the wafers 120.

Furthermore, the control unit 17 can adjust the expansion amount (elongation) of the expansion plate 113 by controlling the upward movement of the expansion drum 61 and the holding platform 62. Moreover, the control unit 17 can set the interval between the individual wafers 120 to a predetermined interval by adjusting the expansion amount of the expansion plate 113.

[Shrinking Step] In this step, with a predetermined spacing already formed between the individual chips 120, the control unit 17 controls the switching valve 639 to connect the holding surface 622 of the holding stage 62 to the suction source 637. Thus, as shown by arrow 302 in Figure 7, the control unit 17 uses the holding surface 622 to attract and hold the corresponding area of the expander 113 on the chip 120 (wafer attachment area 131; see Figure 1), maintaining the spacing between the chips 120 (chip attraction and holding step).

In this state, the control unit 17 controls the moving component 63, as shown by arrow 402 in Figure 8, to move the piston rod 631 to the lower side. Thereby, the control unit 17 lowers the expansion drum 61 and the holding platform 62 to a predetermined retraction position (retraction step) so that the upper surfaces of the holding surface 622 and the expansion auxiliary roller 613 are approximately at the same height as the mounting surface 511 of the cylindrical base 51.

In this way, the expansion auxiliary roller 613 of the expansion drum 61 leaves the expansion plate 113. As a result, the region between the wafer attachment region 131 and the annular frame 111 in the expansion plate 113 (that is, the stretching portion on the outer periphery of the wafer 100), i.e. the shrinkage region 132, becomes relaxed.

Next, as shown in FIG. 9, the control unit 17 positions the infrared heater 81 of the heating component 8 (see FIG. 3) above the shrinkage region 132 in the expansion piece 113, i.e., at the heating position, and turns the infrared heater 81 ON. Hereby, the shrinkage region 132 in the expansion piece 113 is heated by the infrared rays irradiated by the infrared heater 81, and shrinkage occurs as shown in FIG. 10 (wafer shrinkage step). Thus, in the shrinkage step, the shrinkage region 132, which is stretched on the outer periphery of the wafer 100, shrinks due to heating.

Then, the control unit 17 controls the switching valve 639 to disconnect the holding surface 622 of the holding table 62 from the suction source 637. Then, for example, the operator removes the frame unit 110 from the frame holding member 5, thus ending the process.

As described above, in this embodiment, during the wafer spacing formation step, air is ejected from the holding surface 622 of the holding stage 62 located below the expander 113, thereby reducing the friction between the expander 113 and the holding surface 622. Therefore, since the wafer attachment area 131 of the expander 133 can be easily expanded, the predetermined spacing can be well formed between the wafers 120.

Furthermore, during the shrinkage step, by shrinking the shrinkage area 132 in the expander 113, the expander 113 returns to a taut state while maintaining the spacing between the wafers 120 formed during the wafer spacing formation step. Therefore, for example, when the frame unit 110 is transported to a pick-up device (not shown), damage caused by contact between the wafers 120 can be suppressed.

Furthermore, in this embodiment, the heating component 8 has an infrared heater 81. In this regard, the heating component 8 may also have a component that blows hot air into the contraction area 132 instead of the infrared heater 81.

Furthermore, in this embodiment, as shown in Figure 2, a modifier layer 202 is formed on wafer 100 by performing a modifier layer formation step before the wafer spacing formation step. Then, in the wafer spacing formation step, wafer 100 is divided into multiple wafers 120 starting from the modifier layer 202. Regarding this point, in this embodiment, the following dicing step can also be implemented instead of the modifier layer formation step.

[Segmentation Step] In this step, as shown in Figure 11, a dicing groove 212 is formed along the predetermined dicing line 103 of the wafer 100 using a dicing blade 210. As a result, the wafer 100 is divided by the dicing groove 212 into multiple wafers 120, each containing an element 101.

In this case, before the wafer spacing formation step is performed, wafer 100 has been divided into multiple wafers 120. Therefore, in the wafer spacing formation step, the spacing between the wafers 120 in wafer 100 will be expanded to the predetermined spacing.

In this case, during the wafer spacing formation step, air is ejected from the holding surface 622 of the holding stage 62 to reduce the friction between the expander 113 and the holding surface 622. Therefore, since the wafer attachment area 131 of the expander 113 can be easily expanded, the predetermined spacing can be well formed between the wafers 120.

In addition, during the segmentation step, the laser irradiator 200 shown in Figure 2 can also be used to form the segmentation groove 212 by means of laser light.

4: Plate Expansion Device 17: Control Unit 5: Frame Holding Component 40: Base 51: Cylindrical Base 52: Fixture 511: Mounting Surface 6: Plate Expansion Mechanism 61: Expansion Drum 611: Peripheral Wall 612: Bottom Wall 613: Expansion Auxiliary Roller 614: Hole 62: Holding Platform 621: Body 622: Holding Surface 623: Body Vent Path 63: Moving Component 630: Piston Base 631: Piston Rod 632: Support Base 635: Connecting Pipe 636: Air Passage 637: Suction Source 638: Air Source 639: Switching Valve 8: Heating Component 81: Infrared Heater 82: Support Rod 83: Rotating Component 200: Laser Irradiator 201: Laser Beam 210: Cutting Blade 100: Wafer 101: Component 103: Dividing Preset Line 110: Frame Unit 111: Circular Frame 112: Opening 113: Expanding Sheet 120: Chip 131: Wafer Attachment Area 132: Shrinkage Area 202: Modified Layer 212: Dividing Groove

Figure 1 is a perspective view of the frame unit including the wafer. Figure 2 is a cross-sectional view showing the modified layer formation step. Figure 3 is an exploded perspective view of the wafer expansion apparatus. Figure 4 is a cross-sectional view of the wafer expansion apparatus. Figure 5 is a cross-sectional view showing the frame holding step of the wafer spacing formation step. Figure 6 is a cross-sectional view showing the wafer expansion step of the wafer spacing formation step. Figure 7 is a cross-sectional view showing the wafer attraction and holding step of the shrinkage step. Figure 8 is a cross-sectional view showing the removal step of the shrinkage step. Figure 9 is a cross-sectional view showing the wafer shrinkage step of the shrinkage step. Figure 10 is a cross-sectional view showing the sheet shrinkage step of the shrinkage process. Figure 11 is a cross-sectional view showing another example of the modified layer formation step.

5: Frame Holding Component 51: Cylindrical Base 52: Fixture 511: Mounting Surface 61: Expansion Drum 611: Peripheral Wall 612: Bottom Wall 613: Expansion Auxiliary Roller 62: Holding Stage 621: Body 622: Holding Surface 623: Body Ventilation Path 63: Moving Component 630: Piston Base 631: Piston Rod 632: Support Base 635: Connecting Pipe 636: Air Passage 637: Suction Source 638: Air Source 639: Switching Valve 100: Wafer 110: Frame Unit 111: Circular Frame 113: Expansion Sheet 120: Chip 301: Arrowhead 401: Arrowhead

Claims (1)

A method for forming wafer spacing, wherein a predetermined spacing is formed between a plurality of wafers constituting a workpiece supported by an opening in an annular frame via an expansion sheet, the method being characterized by comprising: a wafer spacing forming step, wherein the expansion sheet is expanded by ejecting air from the holding surface to reduce friction between the expansion sheet and the holding surface as the expansion sheet is about to contact the holding surface of a holding stage disposed below the expansion sheet, thereby forming the predetermined spacing between the wafers; and The shrinkage step involves, after the wafer spacing formation step, holding the expansion piece in the area corresponding to the wafer by the holding surface of the holding stage and maintaining the spacing between the wafers, shrinking this portion by heating the portion of the expansion piece between the inner periphery of the annular frame and the outer periphery of the workpiece.