JP7749350B2 - Wafer processing method and expansion device - Google Patents

Description

The present invention relates to a wafer processing method and expansion device.

To manufacture device chips with a die attach layer laminated on the backside, a method using an expansion device to expand tape attached to the backside of the wafer via a die attach film is widely used (see, for example, Patent Document 1).

On the other hand, a tape called 2-in-1, in which a die attach layer is laminated onto an expandable sheet (expandable sheet), is widely used.

In 2-in-1 tape, the diameter of the die attach film is generally made larger than the diameter of the wafer so that the die attach film will adhere to the backside of the wafer even if there is a slight misalignment when attaching the wafer to the expandable sheet.

As a result, when the expandable sheet is expanded, the die attach film that protrudes from the wafer breaks, peels off from the expandable sheet, and scatters. If the scattered die attach film adheres to the surface of the device, it could cause bonding failure.

Therefore, a method has been proposed in which the die attach film protruding from the wafer is removed and then the sheet is expanded (see, for example, Patent Document 2).

Japanese Patent Application Laid-Open No. 2006-049591 Japanese Patent Application Laid-Open No. 2008-192945

However, the method disclosed in Patent Document 2 requires an additional step of removing any excess die attach film before expanding. Furthermore, the die attach film is thin, ranging from a few microns to a few tens of microns, making it extremely difficult to cut just the die attach film along the periphery of the wafer without cutting into the expanding sheet. If cuts are made in the expanding sheet, there is a risk that the expanding sheet will break from the cuts during expansion, so improvements were eagerly sought.

The object of the present invention is to provide a wafer processing method and expansion device that can suppress the occurrence of bonding failures caused by flying fragments of the die attach film without increasing the number of manufacturing processes.

In order to solve the above-mentioned problems and achieve the object, the wafer processing method of the present invention is a wafer processing method, which includes a wafer unit preparation step of preparing a wafer unit comprising a wafer divided along a planned dividing line or a wafer having dividing starting points formed along the planned dividing line, a die attach film attached to the back surface of the wafer and having a diameter larger than that of the wafer, an expandable sheet including an attachment surface to which the wafer is attached via the die attach film, and a frame to which the outer periphery of the expandable sheet is attached; a frame fixing step of fixing the frame of the wafer unit with a frame fixing unit; and an expansion step of pressing with a pressing unit an area between the inner periphery of the frame of the expandable sheet of the wafer unit including a frame fixed with the frame fixing unit from the back side of the attachment surface to expand the expandable sheet, and breaking the die attachable film along the planned dividing line to form a plurality of chips each having the die attachable film attached to its back surface. the pressing unit has a plurality of pressing rollers arranged in a ring shape surrounding the wafer, each arranged in a direction that allows rotation of the wafer in the radial direction, and pressing the expanded sheet; and in the expanding step, a plurality of upper rollers arranged in a ring shape surrounding the wafer are brought into contact with positions on the die attach film that protrudes from the outer periphery of the wafer, corresponding to at least both end edges in the rotational axis direction of each pressing roller, and the die attach film is expanded while being sandwiched together with the expanded sheet between the upper rollers and the pressing rollers, thereby preventing the die attach film from breaking at both end edges in the rotational axis direction of the pressing rollers and peeling off from the expanded sheet; and the pressing rollers are arranged at equal intervals around the circumference of the wafer, and the upper rollers are arranged at equal intervals around the circumference of the wafer, and are arranged in positions that overlap the pressing rollers, and are each arranged in a direction that allows rotation of the wafer in the radial direction, and abut against the die attach film .

The expansion device of the present invention is an expansion device for expanding an expandable sheet of a wafer unit comprising a wafer divided along a planned dividing line or a wafer having dividing starting points formed along the planned dividing line, a die attach film attached to the back surface of the wafer and having a diameter larger than that of the wafer, an expandable sheet including an attachment surface to which the wafer is attached via the die attach film, and a frame to which the outer periphery of the expandable sheet is attached, the expansion device comprising a frame fixing unit for fixing the frame of the wafer unit, and a plurality of pressure rollers arranged in a ring shape surrounding the wafer, each of which is arranged in a direction allowing rotation of the wafer in the radial direction and presses the expandable sheet, and the frame fixed by the frame fixing unit The device is characterized by comprising a pressing unit that presses the area between the inner circumference of the frame and the outer circumference of the wafer from the back side of the surface to be attached, and a pressing unit that has a plurality of upper rollers that are arranged in a ring shape surrounding the wafer and that abut at positions corresponding to at least both end edges in the rotational axis direction of each pressing roller on the die attachment film that protrudes from the outer circumference of the wafer when the pressing unit presses the expanded sheet, wherein the expanded sheet is expanded with the die attachment film sandwiched between the pressing rollers that are arranged at equal intervals around the circumference of the wafer and the upper rollers that are arranged at equal intervals around the circumference of the wafer, positioned so as to overlap between the pressing rollers, and each oriented to allow rotation of the wafer in the radial direction .

The present invention has the advantage of being able to suppress bonding failures caused by flying fragments of the die attach film without increasing the number of manufacturing processes.

FIG. 1 is a perspective view illustrating a configuration example of an extension device according to a first embodiment. FIG. 2 is a perspective view illustrating an example of a wafer unit to be processed by the expansion device according to the first embodiment. FIG. 3 is a cross-sectional view showing a schematic configuration example of a split unit of the expansion device shown in FIG. FIG. 4 is a plan view showing the pressure roller and the upper roller of the dividing unit shown in FIG. FIG. 5 is a cross-sectional view showing a schematic configuration example of a heat shrink unit of the expansion device shown in FIG. FIG. 6 is a flowchart showing the flow of the wafer processing method according to the first embodiment. 7 is a cross-sectional view of a state in which the frame fixing unit of the split unit fixes the frame of the wafer unit in the frame fixing step of the wafer processing method shown in FIG. 6. FIG. FIG. 8 is a cross-sectional view of the wafer unit shown in FIG. 7 with the upper roller in contact with the expanded sheet region. 9 is a cross-sectional view showing a state in which the expansion drum of the division unit is raised and the expand sheet is expanded in the expansion step of the wafer processing method shown in FIG. 6. FIG. FIG. 10 is a cross-sectional view of a state in which the frame fixing unit of the heat shrink unit fixes the frame of the wafer unit in the heat shrink step of the wafer processing method shown in FIG. FIG. 11 is a cross-sectional view of the expandable sheet in the expanded state in the heat shrink step of the wafer processing method shown in FIG. 12 is a cross-sectional view of the heat shrink step of the wafer processing method shown in FIG. 6, in which the wafer unit is suction-held on the holding table of the heat shrink unit, and the push-up member and the holding table are lowered. FIG. 13 is a cross-sectional view showing a state in which the slack in the region of the expand sheet is being heated in the heat shrink step of the wafer processing method shown in FIG. FIG. 14 is a perspective view showing a modified example of the wafer unit shown in FIG.

Modes for carrying out the present invention (embodiments) will be described in detail with reference to the drawings. The present invention is not limited to the contents described in the following embodiments. Furthermore, the components described below include those that would be easily imagined by a person skilled in the art and those that are substantially identical. Furthermore, the configurations described below can be combined as appropriate. Furthermore, various omissions, substitutions, or modifications to the configuration can be made without departing from the spirit of the present invention.

[Embodiment 1]
An expansion device according to a first embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a perspective view showing a configuration example of the expansion device according to the first embodiment. FIG. 2 is a perspective view showing an example of a wafer unit to be processed by the expansion device according to the first embodiment. FIG. 3 is a cross-sectional view schematically showing a configuration example of a split unit of the expansion device shown in FIG. 1. FIG. 4 is a plan view showing a pressure roller and an upper roller of the split unit shown in FIG. 3. FIG. 5 is a cross-sectional view schematically showing a configuration example of a heat shrink unit of the expansion device shown in FIG. 1.

The expansion device 1 shown in FIG. 1 according to the first embodiment is a device that expands the expanding sheet 203 of the wafer unit 200 shown in FIG. 2. As shown in FIG. 2, the wafer unit 200 comprises a wafer 201, a die attach film (hereinafter referred to as DAF) 202, an expanding sheet 203, and a frame 204.

In embodiment 1, the wafer 201 is a disk-shaped semiconductor wafer, optical device wafer, or the like, whose substrate is silicon, sapphire, gallium arsenide, SiC (silicon carbide), or the like. As shown in FIG. 2, the wafer 201 has devices 207 formed in each of the regions defined by a plurality of intersecting planned division lines 206 on the surface 205.

The wafer 201 is irradiated along the planned dividing lines 206 with a laser beam of a wavelength that is transparent to the substrate from the back surface 208 behind the front surface 205, forming modified layers 209 (shown by dotted lines in Figure 2) that serve as dividing starting points along the planned dividing lines 206 inside the substrate. The wafer 201 is divided into individual chips 210 starting from the modified layers 209. Each chip 210 comprises a portion of the substrate divided along the planned dividing lines 206 and a device 207 formed on the front surface of the substrate, with a portion of the divided DAF 202 attached to the back surface 208 of the substrate.

The modified layer 209 refers to a region in which the density, refractive index, mechanical strength, or other physical properties are different from those of the surrounding area, and examples include a melt-processed region, a cracked region, an insulation breakdown region, a refractive index change region, and a region in which these regions are mixed.

The DAF 202 is an adhesive film for die bonding used to fix the individually separated chips 210 to other chips or substrates. The DAF 202 is formed in a circular disk shape with a diameter larger than that of the wafer 201. The DAF 202 is attached to the back surface 208 of the wafer 201.

The expandable sheet 203 is made of a stretchable resin and has heat-shrinkability, meaning it shrinks when heated. The expandable sheet 203 is formed into a disk shape with a diameter larger than that of the wafer 201 and DAF 202, and includes a base layer made of a stretchable and heat-shrinkable synthetic resin, and an adhesive layer made of a stretchable and heat-shrinkable synthetic resin that is laminated on the base layer and adheres to the wafer 201.

The surface of the adhesive layer is the adhered surface 211 to which the DAF 202 is attached and to which the back surface 208 of the wafer 201 is attached via the DAF 202. In other words, the expand sheet 203 includes the adhered surface 211. In embodiment 1, the adhesive layer is made of a synthetic resin that hardens and loses its adhesive strength when irradiated with ultraviolet light.

In embodiment 1, the expand sheet 203 has a DAF 202 attached to its attachment surface 211 in advance, and the DAF 202 is then attached to the back surface 208 of the wafer 201, thereby adhering the expand sheet 203 to the back surface 208 of the wafer 201 via the DAF 202, forming a so-called 2-in-1 tape.

The frame 204 is formed in a circular ring shape with an inner diameter larger than the diameter of the wafer 201 and DAF 202, and the outer periphery of the expandable sheet 203 is attached to it.

The wafer unit 200 having the above-described configuration is constructed by adhering the back surface 208 of the wafer 201 to the DAF 202, which is adhered to the attachment surface 211 of the expandable sheet 203, and adhering the frame 204 to the outer periphery of the expandable sheet 203.

The expansion device 1 according to embodiment 1 shown in Figure 1 is an apparatus that expands the expand sheet 203 of the wafer unit 200, divides the wafer 201, on which a modified layer 209 has been formed as the division starting point, into individual chips 210 along the planned division line 206, and divides the DAF 202 into each chip 210. As shown in Figure 1, the expansion device 1 includes a cassette elevator 3 provided in the main body 2, a division unit 10, a heat shrink unit 30, a cleaning unit 40, an ultraviolet irradiation unit 60, a transport unit 50, and a control unit 100, which is a control means.

The cassette elevator 3 is located at one end of the main body 2 in the Y-axis direction, which is parallel to the horizontal direction, and a cassette 4 containing multiple wafer units 200 is removably placed on it. The cassette 4 contains multiple wafer units 200 spaced apart in the Z-axis direction, which is parallel to the vertical direction. The cassette 4 is placed on the cassette elevator 3 with its opening 5, through which the wafer units 200 can be freely inserted and removed, facing the center of the main body 2 in the Y-axis direction. The cassette elevator 3 raises and lowers the cassette 4 in the Z-axis direction.

The expansion device 1 also includes a pair of first guide rails 6 and a pair of second guide rails 7 on which wafer units 200 to be inserted into or removed from the cassette 4 are temporarily placed. The pair of first guide rails 6 are parallel to the Y-axis direction and are spaced apart in the X-axis direction, which is parallel to the horizontal direction and perpendicular to the Y-axis direction. The pair of first guide rails 6 are located in the center of the device main body 2 in the Y-axis direction so as to align with both ends of the X-axis direction of the opening 5 of the cassette 4 placed on the cassette elevator 3. The pair of first guide rails 6 are movable in the X-axis direction by a drive mechanism (not shown), and are moved toward or away from each other by the drive mechanism. The pair of first guide rails 6 are placed with wafer units 200 to be inserted into or removed from the cassette 4, and when they are moved toward each other by the drive mechanism, they position the wafer units 200 in the X-axis direction.

The pair of second guide rails 7 are used to temporarily place wafer units 200 and other items transported from the first guide rails 6 by the transport unit 50. The pair of second guide rails 7 are parallel to the Y-axis direction, parallel to the horizontal direction, and spaced apart from each other in the X-axis direction. The pair of second guide rails 7 are located in the center of the device main body 2 in the Y-axis direction, and adjacent to the first guide rails 6 in the X-axis direction. The pair of second guide rails 7 are movable in the X-axis direction by a drive mechanism (not shown), and are moved toward and away from each other by the drive mechanism. The pair of second guide rails 7 are used to place wafer units 200 and other items transported from the first guide rails 6, and when they approach each other by the drive mechanism, the wafer units 200 are positioned in the X-axis direction.

The transport unit 50 includes a first transport unit 51 that transports the wafer unit 200 between the cassette 4 and the first guide rail 6, and between the first guide rail 6 and the ultraviolet irradiation unit 60; a second transport unit 52 that transports the wafer unit 200 between the first guide rail 6 and the second guide rail 7, between the second guide rail 7 and the heat shrink unit 30, between the heat shrink unit 30 and the cleaning unit 40, and between the cleaning unit 40 and the first guide rail 6; and a third transport unit 53 that transports the wafer unit 200 between the second guide rail 7 and the splitting unit 10.

The split unit 10 is disposed adjacent to one side of the pair of second guide rails 7 in the Y-axis direction. As shown in FIG. 3, the split unit 10 comprises a frame fixing unit 11, a pressing unit 12, and a holding unit 13. The frame fixing unit 11, the pressing unit 12, and the holding unit 13 are housed in a cooling chamber 14 (shown in FIG. 1), the inside of which is cooled, disposed adjacent to one side of the pair of second guide rails 7 of the device main body 2 in the Y-axis direction.

The frame fixing unit 11 fixes the frame 204 of the wafer unit 200 and includes a frame mounting plate 15 and a frame pressing plate 16. The frame mounting plate 15 is formed as a plate with a circular opening 151 in plan view and a flat top surface 152 parallel to the horizontal direction. The inner diameter of the opening 151 of the frame mounting plate 15 is slightly smaller than the inner diameter of the frame 204 and larger than the diameter of the DAF 202. The frame 204 of the wafer unit 200 is placed on the top surface 152 of the frame mounting plate 15 with the wafer 201 positioned above the opening 151.

In embodiment 1, the frame mounting plate 15 is raised in the Z-axis direction by the cylinder 17 from a position where the upper surface 152 is flush with the lower surface of the frame 204 of the wafer unit 200, which is positioned in the X-axis direction by the second guide rail 7. That is, the frame mounting plate 15 is attached to the tip of the extendable rod 171 of the cylinder 17, and is capable of moving up and down in the Z-axis direction as the rod 171 of the cylinder 17 extends and retracts.

The frame holding plate 16 is fixed above the frame mounting plate 15. The frame holding plate 16 is formed in a plate shape with approximately the same dimensions as the frame mounting plate 15, and has a circular opening 161 in the center with the same dimensions as the opening 151. The opening 161 in the frame holding plate 16 is positioned coaxially with the opening 151 in the frame mounting plate 15.

The frame fixing unit 11 receives the wafer unit 200 and transports it by the third transport unit 53 to the upper surface 152 of the frame mounting plate 15, which is positioned below the rod 171 retracted. After the frame 204 of the wafer unit 200 is placed on the upper surface 152 of the frame mounting plate 15, the rod 171 of the cylinder 17 extends, causing the frame mounting plate 15 to rise. The frame fixing unit 11 clamps and fixes the frame 204 of the wafer unit 200 between the frame presser plate 16 and the raised frame mounting plate 15.

The pressing unit 12 presses the area 212 (shown in Figure 2) between the inner periphery of the frame 204 of the expanded sheet 203 of the wafer unit 200, which includes the frame 204 fixed by the frame fixing unit 11, and the outer periphery of the wafer 201, from the substrate layer side, which is the back side of the adherend surface 211. The pressing unit 12 includes an expansion drum 121 and multiple pressing rollers 122.

In embodiment 1, the expansion drum 121 is cylindrical and closed at the bottom, with a diameter smaller than the inner diameter of the frame 204 placed on the upper surface 152 of the frame mounting plate 15 and larger than the diameter of the wafer 201 attached to the expanding sheet 203. The expansion drum 121 is arranged coaxially with the openings 151, 161 of the frame fixing unit 11.

The pressure rollers 122 are cylindrical and supported at the upper end of the expansion drum 121 so as to be rotatable around an axis (hereinafter referred to as the rotation axis). As shown in Figure 4, the pressure rollers 122 are arranged at equal intervals around the circumferential direction. The pressure rollers 122 are arranged at equal intervals at the upper end of the expansion drum 121, which has an inner diameter smaller than the inner diameter of the frame 204 placed on the upper surface 152 of the frame mounting plate 15 and larger than the diameter of the wafer 201 attached to the expanding sheet 203. As a result, the pressure rollers 122 are arranged in a ring shape surrounding the wafer 201 in a plan view.

The pressure rollers 122 are arranged so that their rotation axes are parallel to the tangent line of the expansion drum 121 in a plan view. The pressure rollers 122 are supported at the upper end of the expansion drum 121 so as to be rotatable around a rotation axis parallel to the tangent line of the expansion drum 121 in a plan view, and are each oriented to allow rotation of the wafer 201 in the radial direction.

The expansion drum 121 is attached to the cylinder 18 and is raised and lowered in the Z-axis direction by the cylinder 18. That is, the expansion drum 121 is attached to the tip of the extendable rod 181 of the cylinder 18, and is capable of being raised and lowered in the Z-axis direction by the extension and contraction of the rod 181 of the cylinder 18.

In embodiment 1, the expansion drum 121 is raised and lowered in the Z-axis direction by the cylinder 18 between a position where the upper end of the pressure roller 122 is located below the upper surface 152 of the frame mounting plate 15 of the frame fixing unit 11 to which the frame 204 is fixed, and a position where the upper end of the pressure roller 122 is located above the upper surface 152 of the frame mounting plate 15 of the frame fixing unit 11 to which the frame 204 is fixed.

When raised by the cylinder 18, the upper end of the pressure roller 122 is positioned above the upper surface 152 of the frame mounting plate 15 of the frame fixing unit 11 that fixes the frame 204, so the pressure roller 122 presses against the region 212 between the inner periphery of the frame 204 of the expand sheet 203 of the wafer unit 200 fixed by the frame fixing unit 11 and the outer periphery of the wafer 201. In embodiment 1, the pressure roller 122 presses against the DAF 202 that is attached to the region 212 of the expand sheet 203 and that protrudes beyond the outer periphery of the wafer 201.

The pressure unit 13 is positioned above the wafer unit 200 fixed by the frame fixing unit 11. As shown in the figure, the pressure unit 13 comprises a pressure drum 131 and a plurality of upper rollers 132, which are abutment members. The pressure drum 131 is cylindrical, with its inner and outer diameters the same as those of each expansion drum 121 and its top closed. The pressure drum 131 is positioned coaxially with the openings 151, 161 of the frame fixing unit 11, i.e., the expansion drums 121.

The upper rollers 132 are cylindrical and supported at the lower end of the pressure drum 131 so as to be rotatable around an axis (hereinafter referred to as the rotation axis). As shown in Figure 4, the upper rollers 132 are arranged at equal intervals around the circumferential direction and are positioned so as to overlap between the pressure rollers 122 in plan view, i.e., so as to overlap both edge edges of the pressure rollers 122 in the direction of the rotation axis.

In embodiment 1, the upper rollers 132 are formed in the same shape as the pressure rollers 122. The upper rollers 132 are arranged at equal intervals at the lower end of the pressure drum 131, which has the same inner and outer diameters as the expansion drum 121, and are arranged in a ring shape surrounding the wafer 201 in a plan view.

The upper roller 132 is arranged so that its rotation axis is parallel to the tangent line of the pressure drum 131 in a plan view. The pressure rollers 122 are supported at the lower end of the pressure drum 131 so as to be rotatable around a rotation axis parallel to the tangent line of the pressure drum 131 in a plan view, and are each oriented to allow rotation in the radial direction of the wafer 201.

The pressure drum 131 is attached to the cylinder 19 and is raised and lowered in the Z-axis direction by the cylinder 19. That is, the pressure drum 131 is attached to the tip of the retractable rod 191 of the cylinder 19, and is capable of being raised and lowered in the Z-axis direction by the extension and contraction of the rod 191 of the cylinder 19.

In embodiment 1, the pressure drum 131 moves up and down in the Z-axis direction by extension and retraction of the rod 191 of the cylinder 19 between a position where the lower end of the upper roller 132 is flush with the upper surface 152 of the frame mounting plate 15 of the frame fixing unit 11 to which the frame 204 is fixed, and a position where the lower end of the upper roller 132 is higher than the upper surface 152 of the frame mounting plate 15 of the frame fixing unit 11 to which the frame 204 is fixed.

When the rod 191 of the cylinder 19 extends and descends, the lower end of the upper roller 132 is positioned flush with the upper surface 152 of the frame mounting plate 15 of the frame fixing unit 11 that fixes the frame 204. As a result, when the pressing unit 12 presses the expanded sheet 203, the upper roller 132 abuts at positions corresponding to both end edges of each pressing roller 122 in the rotational axis direction of the DAF 202 that protrudes from the outer periphery of the wafer 201.

The presser unit 13 also includes a spring 20, a biasing means, fixed between the rod 191 of the cylinder 19 and the presser drum 131. The spring 20 expands and contracts to allow the presser drum 131 and upper roller 132 to move up and down in the Z-axis direction relative to the rod 191 of the cylinder 19. The expansion and contraction of the spring 20 allows the upper roller 132 to move up and down in the Z-axis direction from a position where the lower end of the upper roller 132 is flush with the upper surface 152 of the frame mounting plate 15 of the frame fixing unit 11 to which the frame 204 is fixed, without the rod 191 expanding or contracting.

In embodiment 1, the split unit 10 is arranged such that, in a plan view, the pressure roller 122 and the upper roller 132 have their rotation axes positioned on the same circle, and the rotation axes of the pressure roller 122 and the upper roller 132 overlap in the Z-axis direction.

The split unit 10 fixes the frame 204 of the wafer unit 200 with the frame fixing unit 11, positions the pressure drum 131 at a position where the lower end of the upper roller 132 is flush with the upper surface 152 of the frame mounting plate 15 of the frame fixing unit 11 to which the frame 204 is fixed, and raises the expansion drum 121 from a position where the upper end of the pressure roller 122 is lower than the upper surface 152 of the frame mounting plate 15 of the frame fixing unit 11 to which the frame 204 is fixed, thereby pressing the area 212 between the inner periphery of the frame 204 of the expand sheet 203 of the wafer unit 200 and the outer periphery of the wafer 201, thereby expanding the expand sheet 203 in the planar direction. In addition, the split unit 10 first expands the expand sheet 203, and then lowers the expansion drum 121, creating slack in the region 212 between the inner periphery of the frame 204 of the expand sheet 203 of the wafer unit 200 and the outer periphery of the wafer 201.

The heat shrink unit 30 is disposed adjacent to the other side of the pair of second guide rails 7 in the Y-axis direction. As shown in FIG. 5, the heat shrink unit 30 includes a holding table 32, a frame fixing unit 31, a sheet expansion unit 36, and a heating unit 37.

The holding table 32 has a holding surface 321 that suction-holds the wafers 201 of the wafer unit 200 via the expandable sheet 203. The holding table 32 is disk-shaped with a diameter smaller than the inner diameter of the frame 204, and includes a disk-shaped frame 322 made of a metal such as stainless steel, and a disk-shaped suction portion 323 made of a porous material such as porous ceramic and surrounded by the frame 322.

The upper surfaces of the frame 322 and the suction part 323 are arranged on the same plane, forming a holding surface 321 that holds the wafer 201 by suction. The suction part 323 has approximately the same diameter as the wafer 201. The suction part 323 is connected to a suction source 325, such as an ejector, via a suction path 324 formed in the frame 322 or the like. The suction path 324 is provided with an on-off valve 326.

The back surface 208 of the wafer 201 of the wafer unit 200 transported by the second transport unit 52 is placed on the holding surface 321 of the holding table 32 via the expand sheet 203. When the on-off valve 326 is opened, the suction source 325 sucks the suction portion 323 of the holding surface 321, thereby suction-holding the back surface 208 of the wafer 201 to the holding surface 321.

The frame fixing unit 31 fixes the frame 204 of the wafer unit 200. The frame fixing unit 31 includes a frame mounting plate 33 and a frame holding plate 34. The frame mounting plate 33 has a circular opening 331 in plan view and a flat, plate-like top surface 332 parallel to the horizontal direction. The inner diameter of the opening 331 of the frame mounting plate 33 is slightly smaller than the inner diameter of the frame 204 and larger than the diameter of the DAF 202. The frame mounting plate 33 accommodates the holding table 32 within the opening 331, and the opening 331 is arranged coaxially with the holding table 32. As shown in FIG. 1 , the frame mounting plate 33 is provided with centering guides 333 that are horizontally movable at the four corners of the top surface 332 and that move horizontally to adjust the position of the frame 204 and position the wafer 201 coaxially with the suction portion 323 of the holding surface 321 of the holding table 32.

The frame mounting plate 33 is also provided so that it can be raised and lowered in the Z-axis direction by a cylinder 35. That is, the frame mounting plate 33 is attached to the tip of the extendable rod 351 of the cylinder 35, and is provided so that it can be raised and lowered in the Z-axis direction by the extension and contraction of the rod 351 of the cylinder 35.

The frame pressing plate 34 is formed in a plate shape with approximately the same dimensions as the frame mounting plate 33, and has a circular opening 341 in its center with the same dimensions as the opening 331. The frame pressing plate 34 is attached to the tip of the piston rod of a cylinder (not shown), and is movable between a position above the frame mounting plate 33 and a position retracted from above the frame mounting plate 33 as the piston rod extends and retracts along the Y-axis direction. As shown in Figure 1, the frame pressing plate 34 has elongated holes 342 at its four corners, into which the centering guides 333 can enter.

The frame fixing unit 31 is positioned so that the frame pressing plate 34 is retracted from above the frame mounting plate 33, and the frame 204 of the wafer unit 200 transported by the second transport unit 52 is placed on the upper surface 332 of the frame mounting plate 33 with the centering guides 333 spaced apart. The frame fixing unit 31 brings the centering guides 333 closer together to position the wafer 201 of the wafer unit 200. The frame fixing unit 31 positions the frame pressing plate 34 above the frame mounting plate 33, and the frame mounting plate 33 is raised by the cylinder 35, sandwiching and fixing the frame 204 of the wafer unit 200 between the frame mounting plate 33 and the frame pressing plate 34.

The sheet expansion unit 36 expands the expanding sheet 203 by moving the holding table 32 and the frame fixing unit 31 relatively along a vertical axis to positions away from each other. As shown in Figure 5, the sheet expansion unit 36 includes a push-up member 361, a push-up member lifting unit 362, and a holding table lifting unit 363.

The push-up member 361 is cylindrical and has a diameter smaller than the inner diameter of the frame 204 placed on the upper surface 332 of the frame mounting plate 33, but larger than the diameter of the wafer 201 attached to the expandable sheet 203 and the holding table 32. The push-up member 361 has the holding table 32 located inside, and is arranged coaxially with the holding table 32. A pressure roller 364 is rotatably attached to the upper end of the push-up member 361.

The push-up member lifting unit 362 raises and lowers the push-up member 361 in the Z-axis direction between a position where the pressure roller 364 is positioned below the upper surface 332 of the lowered frame mounting plate 33 and a position where it is positioned above the upper surface 332 of the raised frame mounting plate 33.

The holding table lifting unit 363 raises and lowers the holding table 32 in the Z-axis direction between a position where the holding surface 321 is located below the upper surface 332 of the lowered frame mounting plate 33 and a position where it is located above the upper surface 332 of the raised frame mounting plate 33.

The heating unit 37 heats and contracts the slack in the region 212 between the frame 204 and the wafer 201 of the expanding sheet 203 formed by expanding the expanding sheet 203 using the dividing unit 10. The heating unit 37 has multiple heating sections 371 that are movable in the Z-axis direction and rotate around an axis parallel to the Z-axis direction.

The heating units 371 are arranged at equal intervals in the circumferential direction above the area 212 of the expanding sheet 203 of the wafer unit 200, which includes the frame 204 fixed by the frame fixing unit 31, and are arranged on a circle corresponding to the area 212 of the expanding sheet 203. The heating units 371 are arranged at positions facing the area 212 of the expanding sheet 203 of the wafer unit 200 held by the holding table 32 and the frame fixing unit 31 in the Z-axis direction. In embodiment 1, four heating units 371 are provided at equal intervals in the circumferential direction, but the present invention is not limited to four.

The heating unit 371 is a type that irradiates infrared rays downward to heat the region 212 of the expanding sheet 203; for example, it is an infrared ceramic heater that heats up when voltage is applied and emits infrared rays. The heating unit 371 rotates around an axis coaxial with the axis of the holding table 32, and orbits over the aforementioned region 212 of the expanding sheet 203.

The heating unit 37 has its heating section 371 lowered to vertically face the region 212 of the expanding sheet 203 of the wafer unit 200 held by the holding table 32 and frame fixing unit 31, and rotates around its axis to orbit over the aforementioned region 212 of the expanding sheet 203, thereby heating and contracting any slack in the region 212 of the expanding sheet 203.

The cleaning unit 40 primarily cleans the wafers 201 of the wafer unit 200, whose expanding sheet 203 has been expanded by the split unit 10 and whose slack has been heated and shrunk by the heat shrink unit 30. The cleaning unit 40 includes a spinner table 41 that is positioned below the pair of first guide rails 6 and that suction-holds the wafers 201 via the expanding sheet 203 of the wafer unit 200, and a cleaning water supply nozzle (not shown) that supplies cleaning water to the surface 205 of the wafer 201 held by suction on the spinner table 41.

When the pair of first guide rails 6 separate, the cleaning unit 40 heats the slack in the heat shrink unit 30 via the second transport unit 52, and the shrunk wafer unit 200 is placed on the spinner table 41. The cleaning unit 40 rotates the spinner table 41 around an axis parallel to the Z-axis direction while supplying cleaning water from a cleaning water supply nozzle onto the surface 205 of the wafer 201 to clean the wafer 201.

The ultraviolet irradiation unit 60 irradiates the expandable sheet 203 of the wafer unit 200 cleaned by the cleaning unit 40 with ultraviolet light to harden the adhesive layer and reduce the adhesive strength of the adhesive layer. The ultraviolet irradiation unit 60 is located at the other end of the device main body 2 in the Y-axis direction, and is located next to one side of the first guide rail 6 in the Y-axis direction.

The ultraviolet irradiation unit 60 receives the cleaned wafer unit 200 on the first guide rail 6 by the first transport unit 51, and irradiates the expanded sheet 203 of the wafer unit 200 with ultraviolet light for a predetermined period of time. The ultraviolet irradiation unit 60 then receives the wafer unit 200 irradiated with ultraviolet light by the first transport unit 51 and transports it onto the first guide rail 6.

The control unit 100 controls the above-mentioned components of the expansion device 1, i.e., at least the heating means 38, etc., and causes the expansion device 1 to perform processing operations on the wafer 201. The control unit 100 is a computer that includes an arithmetic processing device with a microprocessor such as a CPU (central processing unit), a storage device with memory such as ROM (read only memory) or RAM (random access memory), and an input/output interface device. The arithmetic processing device of the control unit 100 performs arithmetic processing in accordance with a computer program stored in the storage device, and outputs control signals for controlling the expansion device 1 to the above-mentioned components of the expansion device 1 via the input/output interface device.

The control unit 100 is connected to a display unit (not shown) consisting of an LCD display or the like that displays the status of the machining operation and images, and an input unit (not shown) that the operator uses to register machining content information, etc. The input unit consists of at least one of a touch panel provided on the display unit and an external input device such as a keyboard.

Next, a wafer processing method according to embodiment 1 will be described. Figure 6 is a flowchart showing the flow of the wafer processing method according to embodiment 1. The wafer processing method according to embodiment 1 involves expanding the expand sheet 203 of the wafer unit 200, breaking the wafer 201 starting from the modified layer 209, dividing the wafer 201 into individual chips 210, and dividing the DAF 202 into each individual chip 210 along the planned division lines 206. As shown in Figure 6, the wafer processing method includes a wafer unit preparation step 301, a frame fixing step 302, an expansion step 303, a heat shrink step 304, a cleaning step 305, and an ultraviolet light irradiation step 306.

(Wafer unit preparation step)
The wafer unit preparation step 301 is a step for preparing the wafer unit 200 having the above-described configuration. In the wafer unit preparation step 301, the back surface 208 of the wafer 201 is attached to the DAF 202 attached to the expanding sheet 203, and the frame 204 is cauterized around the outer periphery of the expanding sheet 203 to form the wafer unit 200. In the wafer unit preparation step 301 in the first embodiment, an operator or the like places the wafer unit 200 in the cassette 4, and the expansion device 1 places the cassette 4 containing the plurality of wafer units 200 on the cassette elevator 3.

Furthermore, in embodiment 1, in wafer unit preparation step 301, the control unit 100 receives processing content information via the input unit and stores it in a storage device. In embodiment 1, in frame fixing step 302, when the control unit 100 receives a processing start instruction from the operator, the process proceeds to frame fixing step 302.

(frame fixing step)
Fig. 7 is a cross-sectional view showing a state in which a frame fixing unit of a division unit fixes a frame of a wafer unit in the frame fixing step of the wafer processing method shown in Fig. 6. Fig. 8 is a cross-sectional view showing a state in which an upper roller is abutted against an expanded sheet region of the wafer unit shown in Fig. 7.

The frame fixing step 302 is a step in which the frame 204 of the wafer unit 200 is fixed by the frame fixing unit 11 of the split unit 10. In the frame fixing step 302, the expansion device 1, with the expansion drum 121 of the split unit 10 lowered, removes one wafer unit 200 from the cassette 4 using the first transport unit 51, temporarily places the wafer unit 200 on the pair of first guide rails 6, and then moves the pair of first guide rails 6 closer to each other to position the wafer unit 200 in the X-axis direction.

In the frame fixing step 302, the expansion device 1 uses the second transport unit 52 to transport the wafer unit 200 on the first guide rails 6 onto the second guide rails 7, and then moves the pair of second guide rails 7 toward each other to position the wafer unit 200 in the X-axis direction. In the frame fixing step 302, the expansion device 1 uses the third transport unit 53 to transport the wafer unit 200 on the pair of second guide rails 7 onto the upper surface 152 of the lowered frame mounting plate 15 of the split unit 10, as shown in FIG. 7.

In the frame fixing step 302, the expansion device 1 raises the frame mounting plate 15 of the split unit 10 as shown in FIG. 8, and clamps the frame 204 between the frame pressing plate 16 and the frame mounting plate 15 to fix the wafer unit 200. In the frame fixing step 302, the expansion device 1 lowers the pressing drum 131 of the split unit 10 as shown in FIG. 8, and abuts the lower end of the upper roller 132 against the region 212 of the expanded sheet 203 of the wafer unit 200, including the frame 204 fixed by the frame fixing unit 11.

(extension step)
Figure 9 is a cross-sectional view showing a state in which the expansion drum of the dividing unit is raised and the expand sheet is expanded in the expansion step of the wafer processing method shown in Figure 6. The expansion step 303 is a step in which a region 212 of the expand sheet 203 of the wafer unit 200 including the frame 204 fixed by the frame fixing unit 11 is pressed from the base layer side by the pressing unit 12 to expand the expand sheet 203, and the DAF 202 is broken along the planned division line 206 to form a plurality of chips 210 having the DAF 202 attached to the back surface 208.

In the expansion step 303, the expansion device 1 raises the expansion drum 121. This causes the pressure roller 122 provided at the upper end of the expansion drum 121 to come into contact with the area 212 of the expanding sheet 203, and the pressure roller 122 presses the area 212 from below upward, causing the expanding sheet 203 to expand in the planar direction. In the expansion step 303, as a result of the expansion of the expanding sheet 203, a radial tensile force acts on the expanding sheet 203.

When a radial tensile force acts on the expandable sheet 203 attached to the back surface 208 of the wafer 201, the wafer 201 is divided into individual chips 210 along the planned division lines 206, starting from the modified layer 209, because the modified layer 209 has been formed along the planned division lines 206. Furthermore, the wafer 201 widens between the chips 210, forming gaps between them. Furthermore, when a radial tensile force acts on the expandable sheet 203, the DAF 202 breaks into individual chips 210 along the modified layer 209, i.e., the planned division lines 206.

Furthermore, in the expansion step 303, the expansion device 1 abuts the upper roller 132 at a position on the DAF 202 that protrudes from the outer periphery of the wafer 201 corresponding to at least both end edges of each pressure roller 122 in the rotational axis direction, and raises the upper roller 132 and pressure roller 122 against the biasing force of the spring 20. Therefore, in the expansion step 303, the expansion device 1 expands the DAF 202 with the expanding sheet 203 sandwiched between the upper roller 132 and pressure roller 122 while the spring 20 generates an elastic restoring force that presses the upper roller 132 toward the pressure roller 122, causing the pressure roller 122 to press the region 212 from below to above.

In this way, in the expansion step 303, the expansion device 1 expands the DAF 202 while sandwiching it between the upper roller 132 and the pressure roller 122 together with the expanding sheet 203, thereby preventing the DAF 202 from breaking at both ends in the rotational axis direction of the pressure roller 122 and peeling off from the expanding sheet 203. In the expansion step 303, the expansion device 1 lowers the expansion drum 121 of the split unit 10. Then, because the expanding sheet 203 has been temporarily expanded, slack is formed in the region 212 of the expanding sheet 203 in the wafer unit 200.

(Heat shrink step)
Fig. 10 is a cross-sectional view showing a state in which a frame fixing unit of a heat shrink unit fixes a frame of a wafer unit in the heat shrink step of the wafer processing method shown in Fig. 6. Fig. 11 is a cross-sectional view showing a state in which an expandable sheet is expanded in the heat shrink step of the wafer processing method shown in Fig. 6. Fig. 12 is a cross-sectional view showing a state in which a wafer unit is suction-held on a holding table of a heat shrink unit in the heat shrink step of the wafer processing method shown in Fig. 6, and a state in which a push-up member and a holding table are lowered. Fig. 13 is a cross-sectional view showing a state in which a slack region of an expandable sheet is heated in the heat shrink step of the wafer processing method shown in Fig. 6.

The heat shrink step 304 is a step in which the slack in the area 212 of the expand sheet 203 of the wafer unit is heated and shrunk. In the heat shrink step 304, the expansion device 1 lowers the frame mounting plate 15 of the frame fixing unit 11 of the split unit 10, and the third transport unit 53 transports the wafer unit 200 on the frame mounting plate 33 onto the pair of second guide rails 7.

In the heat shrink step 304, the expansion device 1 lowers the push-up member 361 and holding table 32 of the heat shrink unit 30 and positions the frame pressing plate 34 of the frame fixing unit 31 in the retracted position, and then uses the second transport unit 52 to transport the wafer unit 200 on the second guide rail 7 onto the upper surface 332 of the frame mounting plate 33.

In the heat shrink step 304, the expansion device 1 brings the centering guides 333 of the frame fixing units 31 closer to each other to position the wafer 201 of the wafer unit 200. In the heat shrink step 304, the expansion device 1 raises the frame mounting plate 33 and, as shown in Figure 10, sandwiches the frame 204 between the frame mounting plate 33 and the frame holding plate 34 to fix the wafer unit 200.

In the heat shrink step 304, the expansion device 1 raises the push-up member 361 and holding table 32 of the heat shrink unit 30, stretching the area 212 of the expanded expand sheet 203 as shown in FIG. 11, and creating spaces between the chips 210. In the heat shrink step 304, the expansion device 1 opens the on-off valve 326 and applies suction to the suction section 323 using the suction source 325, thereby suction-holding the back surface 208 of the wafer 201 to the holding surface 321 via the expand sheet 203, thereby maintaining the spaces between the chips 210.

In the heat shrink step 304, as shown in FIG. 12, the expansion device 1 lowers the push-up member 361 below the upper surface 332 of the frame mounting plate 33, and lowers the holding table 32 until the holding surface 321 is positioned on the same plane as the upper surface 332 of the frame mounting plate 33. This causes slack in the region 212 of the expanding sheet 203.

In the heat shrink step 304, the expansion device 1 lowers the heating unit 37 of the heat shrink unit 30 so that the heating section 371 faces the region 212 of the expanding sheet 203. In embodiment 1, in the heat shrink step 304, the expansion device 1 drives all of the heating sections 371 of the heating unit 37 of the heat shrink unit 30, causing all of the heating sections 371 to radiate infrared rays while rotating the heating sections 371 a predetermined number of times above the region 212. In this way, in the heat shrink step 304, the expansion device 1 heats the slack in the region 212 all around, causing it to shrink.

(Washing step)
The cleaning step 305 is a step in which the wafer 201 is cleaned in the cleaning unit 40 after the heat shrink step 304 is performed. In the cleaning step 305, the expansion apparatus 1 stops the rotation and heating of the heating section 371 of the heating unit 37 of the heat shrink unit 30, lowers the frame mounting plate 33 of the frame fixing unit 31 of the heat shrink unit 30, and stops suction holding of the holding table 32, etc. In the cleaning step 305, the expansion apparatus 1 transports the wafer unit 200 to the cleaning unit 40 using the second transport unit 52. In the cleaning step 305, the expansion apparatus 1 cleans the wafer unit 200 in the cleaning unit 40.

(Ultraviolet irradiation step)
The ultraviolet irradiation step 306 is a step of irradiating ultraviolet rays onto the expanding sheet 203 of the cleaned wafer unit 200. In the ultraviolet irradiation step, the expansion device 1 transports the wafer unit 200 from the cleaning unit 40 to the ultraviolet irradiation unit 60 using the second transport unit 52 and the first transport unit 51.

In the ultraviolet irradiation step 306, the expansion device 1 irradiates the wafer unit 200 with ultraviolet light for a predetermined period of time using the ultraviolet irradiation unit 60, and then stores the wafer unit 200 in the cassette 4 using the first transport unit 51. The expansion device 1 sequentially expands the expand sheets 203 of the wafer units 200 in the cassette 4 to divide the wafers 201 into individual chips 210, and when the expansion sheets 203 of all wafer units 200 in the cassette 4 have been expanded to divide the wafers 201 into individual chips 210, the processing operation is completed.

As described above, the wafer processing method and expansion device 1 according to embodiment 1 expands the expanding sheet 203 in the expansion step 303 while sandwiching the expanding sheet 203 and the DAF 202 between the pressure roller 122 and the upper roller 132. Therefore, even if the DAF 202 breaks at both ends in the rotational axis direction of the pressure roller 122 in the expansion step 303, the wafer processing method and expansion device 1 according to embodiment 1 presses the determined DAF 202 against the expanding sheet 203 with the upper roller 132.

Therefore, the wafer processing method and expansion device 1 according to embodiment 1 can prevent the DAF 202 from peeling off and scattering from the expanding sheet 203 without having to perform a step of removing the portion of the DAF 202 that protrudes beyond the outer periphery of the wafer 201 before expanding the expanding sheet 203. As a result, the wafer processing method and expansion device 1 according to embodiment 1 have the effect of preventing bonding defects in the chip 210 caused by scattering of fragments of the DAF 202 without increasing the number of manufacturing steps.

The present invention is not limited to the above embodiment. In other words, various modifications can be made without departing from the gist of the present invention. In embodiment 1, modified layer 209 was formed as the starting point for division, but the present invention is not limited to this, and laser-processed grooves or machined grooves may also be formed as starting points for division.

Furthermore, in embodiment 1, the expansion device 1 may be configured such that the wafer 201 of the wafer unit 200 is divided into individual chips 210 along the planned division line 206 by division grooves 214 formed on the planned division line 206, as shown in FIG. 14.

Note that Figure 14 is a perspective view showing a modified example of the wafer unit shown in Figure 2. In Figure 14, the same parts as in embodiment 1 are designated by the same reference numerals, and their description will be omitted. The dividing grooves 214 penetrate the wafer 201 and divide the wafer 201 into individual chips 210, and are formed by cutting or laser ablation of the wafer 201.

In other words, in the present invention, the wafer processing method and expansion device 1 prepare a wafer unit 200 including a wafer 201 divided along a planned division line 206 in a wafer unit preparation step 301, and in an expansion step 303, divide the DAF 202 into individual chips 210, and may widen the spacing between the chips 210 compared to before the expansion step 303.

Furthermore, in the present invention, as long as the expanding sheet 203 and the DAF 202 can be sandwiched between the pressure roller 122 and the upper roller 123, the radial positions of the wafer 201 between the pressure roller 122 and the upper roller 123 may be different.

1 Expansion device 11 Frame fixing unit 12 Pressing unit 13 Pressing unit 122 Pressing roller 132 Upper roller (contact member)
200 wafer unit 201 wafer 202 DAF (die attach film)
203 Expanded sheet 204 Frame 206 Planned division line 208 Back surface 209 Modified layer (division starting point)
210 Chip 211 Adhesion surface 212 Area 301 Wafer unit preparation step 302 Frame fixing step 303 Expansion step

Claims (2)

A wafer processing method comprising:
a wafer unit preparation step of preparing a wafer unit comprising a wafer divided along a planned dividing line or a wafer on which dividing starting points are formed along the planned dividing line, a die attach film attached to the back surface of the wafer and having a diameter larger than that of the wafer, an expandable sheet including an attachment surface to which the wafer is attached via the die attachable film, and a frame to which the outer periphery of the expandable sheet is attached;
a frame fixing step of fixing the frame of the wafer unit with a frame fixing unit;
an expansion step of pressing an area between the inner periphery of the frame of the expand sheet of the wafer unit including a frame fixed by the frame fixing unit and the outer periphery of the wafer from the back side of the attachment surface with a pressing unit to expand the expand sheet, and breaking the die attach film along the planned division lines to form a plurality of chips with the die attach film attached to their back surfaces,
The pressing unit has a plurality of pressing rollers arranged in a ring shape surrounding the wafer, each of which is oriented in a direction that allows rotation of the wafer in the radial direction and presses the expand sheet,
In the expansion step, a plurality of upper rollers arranged in a ring shape surrounding the wafer are brought into contact with the die attachment film that protrudes from the outer periphery of the wafer at positions corresponding to at least both end edges in the direction of the rotation axis of each pressing roller, and the die attachment film is expanded while sandwiched between the upper rollers and the pressing rollers together with the expanded sheet, thereby preventing the die attachment film from breaking and peeling off from the expanded sheet at both end edges in the direction of the rotation axis of the pressing rollers, and
a plurality of pressure rollers are arranged at equal intervals around the circumference of the wafer, and a plurality of upper rollers are arranged at equal intervals around the circumference of the wafer, and are positioned so as to overlap between the pressure rollers, and are each oriented in a direction that allows rotation of the wafer in the radial direction, so as to abut against the die attach film , in a wafer processing method. An expansion device for expanding an expandable sheet of a wafer unit, the expandable sheet comprising: a wafer divided along a planned dividing line or a wafer having dividing starting points formed along the planned dividing line; a die attach film attached to the back surface of the wafer and having a diameter larger than that of the wafer; an expandable sheet including an attachment surface to which the wafer is attached via the die attachable film; and a frame to which the outer periphery of the expandable sheet is attached,
a frame fixing unit that fixes the frame of the wafer unit;
a pressing unit having a plurality of pressing rollers arranged in a ring shape surrounding the wafer, each of which is oriented in a direction that allows the wafer to rotate in the radial direction and presses the expanded sheet, and which presses the area between the inner periphery of the frame of the expanded sheet of the wafer unit including a frame fixed by the frame fixing unit and the outer periphery of the wafer from the back side of the surface to be attached;
a pressing unit having a plurality of upper rollers arranged in a ring shape surrounding the wafer, the upper rollers contacting the die attach film protruding from the outer periphery of the wafer at positions corresponding to both end edges in the rotation axis direction of each pressing roller when the pressing unit presses the expand sheet,
An expansion device that expands the expanding sheet while sandwiching the die attach film together with the expanding sheet between a plurality of pressure rollers arranged at equal intervals around the circumference of the wafer and a plurality of upper rollers arranged at equal intervals around the circumference of the wafer, positioned so as to overlap between the pressure rollers, and oriented so as to allow rotation of the wafer in the radial direction .