JP2005086074A - Transfer method of semiconductor wafer - Google Patents

Abstract

In a case where a back surface of a semiconductor wafer having a protective tape attached to the front surface is attached to a dicing tape and the protective tape is peeled off from the front surface, the protective tape is easily peeled off without damaging the semiconductor wafer.
A back surface of a semiconductor wafer is ground in a state where a protective tape that decreases in adhesive strength upon receiving an external stimulus is adhered to the surface of the semiconductor wafer, and the adhesive strength is affected by receiving the same external stimulus. The back surface of the ground semiconductor wafer 1 is adhered to the dicing tape 4 to be lowered and integrated with the dicing frame, and the protective tape 2 is peeled off from the surface of the semiconductor wafer after applying external stimulus to the protective tape 2 side.
[Selection] Figure 10

Description

  The present invention relates to a method of sticking the back surface of a semiconductor wafer whose back surface is ground in a state where the protective tape is stuck on the surface to a dicing tape, and peeling the protective tape stuck on the surface.

  A semiconductor wafer having a plurality of circuits formed on the front surface side is formed to a predetermined thickness by grinding the back surface. In recent years, in order to reduce the thickness of a semiconductor chip, it is required to grind the back surface until the thickness becomes extremely thin such as 100 μm or less and 50 μm or less at the wafer stage.

  When grinding the back surface, the front side is placed on the chuck table of the grinding device, and thus a protective tape is attached to the surface to protect the circuit. Then, after grinding the back side with the front side placed on the chuck table to form the semiconductor wafer to the desired thickness, the back side of the semiconductor wafer is replaced with dicing tape and integrated with the dicing frame to protect it from the front side After the tape is peeled off, the wafer is divided into individual semiconductor chips by dicing. Thereafter, the semiconductor chips are individually picked up with the back surface attached to a dicing tape.

In addition, so-called first dicing is performed in which a groove having a depth corresponding to the thickness of the semiconductor chip is formed on the surface of the semiconductor wafer, and the back surface is ground and the groove is exposed from the back surface to be divided into individual semiconductor chips. In the technology called, after the back surface is ground and the groove is exposed to divide into semiconductor chips with the protective tape attached to the surface, the surface is attached to the protective tape and the semiconductor wafer as a whole After the semiconductor chip maintaining the above is replaced with a dicing tape, a plurality of semiconductor chips are individually picked up (see, for example, Patent Document 1).
JP 2003-7653 A

  However, if the outer diameter of the protective tape is slightly larger than the outer diameter of the semiconductor wafer in order to reliably protect the outer periphery of the semiconductor wafer, the semiconductor wafer becomes thinner by grinding, so the back surface of the semiconductor wafer is diced. There is a problem that when the tape is attached to the tape, the protective tape wraps the semiconductor wafer from the outer peripheral side, the outer peripheral portion of the protective tape is attached to the dicing tape, and the protective tape cannot be peeled off. In addition, if the separation is forced, the protective tape pulls up the dicing tape, and the semiconductor wafer is damaged. In addition, the semiconductor wafer after the back surface grinding is formed to be thin, for example, with a thickness of 100 μm or less, and thus is easily damaged.

  In addition, in the case of a semiconductor wafer whose outer peripheral side surface is chamfered in an arc shape in order to prevent chipping or the like in the process of processing, the outer diameter of the semiconductor wafer becomes smaller when the back surface is ground. Protrudes from the outer peripheral side of the semiconductor wafer, and the difference between the outer diameter of the protective tape and the outer diameter of the semiconductor wafer becomes large. In this case, the outer peripheral portion of the protective tape is stuck to the dicing tape, and the protective tape is peeled off. There is a problem that it cannot be done.

  Such a problem also occurs when using a tip dicing technique, when a plurality of semiconductor chips that maintain the shape of the semiconductor wafer as a whole are picked up individually and then replaced with dicing tape after the backside grinding. It is a problem that occurs.

  In this way, when the back surface of the semiconductor wafer with the protective tape attached to the front surface is attached to the dicing tape and the protective tape is peeled off from the front surface, the protective tape is easily peeled off to prevent damage to the semiconductor wafer. Therefore, the present invention solves this problem.

  In order to solve the above-mentioned problems, the present invention provides an adhesive that is externally stimulated when a semiconductor wafer is transferred to a dicing frame after the back surface of the semiconductor wafer having a circuit formed on the front surface is ground. Grind the backside of the semiconductor wafer with a protective tape that reduces the adhesive strength applied to the surface of the semiconductor wafer, and apply the backside of the ground semiconductor wafer to a dicing tape that has the same adhesive force to reduce the adhesive force. The gist is that the protective tape is peeled off from the surface of the semiconductor wafer after being attached to the dicing frame and applied with an external stimulus to the protective tape side. The protective tape and the dicing tape may be made of the same material, or may have different adhesive strength even if the materials are different, as long as the adhesive force is reduced by the same external stimulus.

  The semiconductor wafer may be one whose outer peripheral side surface is chamfered in an arc shape or may not be chamfered. Further, the outer diameter of the protective tape may be equal to the outer diameter of the semiconductor wafer, or the outer diameter of the protective tape may be formed larger.

  As an external stimulus, for example, there is ultraviolet light, but other stimulus such as heating may be used. Further, the semiconductor wafer includes a semiconductor wafer that is divided into semiconductor chips by a method of prior dicing. In the case of tip dicing, the back surface is ground in the grinding process, so that grooves are exposed and divided into individual semiconductor chips, but since the protective tape is stuck on the surface, the shape of the wafer as a whole The semiconductor wafer is the one that maintains its shape after the division.

  In the present invention, a protective tape that adheres to the surface of a semiconductor wafer is used as a protective tape whose adhesive strength is reduced by receiving an external stimulus, and the same applies to a dicing tape that is attached to the back surface of a semiconductor wafer. Since the surface of the semiconductor wafer is attached to the surface of the semiconductor wafer and the back surface of the semiconductor wafer is attached to the dicing tape to give external stimulus to the protective tape, the protective tape and dicing are used. Even if the tape is bonded, the adhesive strength of both tapes can be reduced for the bonded portion. In addition, external stimuli are shielded by the semiconductor wafer at the portion where the semiconductor wafer and the dicing tape are adhered, and the adhesive strength of the dicing tape does not decrease. Therefore, in the protective tape peeling process, the back surface of the semiconductor wafer is firmly held by the dicing tape, and the adhesive strength of the bonding portion between the protective tape and the dicing tape is reduced, so the protective tape is easy to use. And it can peel smoothly and can prevent a semiconductor wafer from being damaged. In particular, even if the thickness of the semiconductor wafer is extremely thin such as 100 μm or less by the grinding process, the semiconductor wafer can be attached to the dicing tape without damaging it.

  Also, when the outer peripheral side surface of the semiconductor wafer is formed in an arc shape, or when the outer diameter of the protective tape is larger than the outer diameter of the semiconductor wafer, the thickness of the semiconductor wafer is extremely thin, such as 100 μm or less. When the semiconductor wafer is bonded to the dicing tape, the protective tape and the dicing tape are often bonded to each other. It is effective to reduce the adhesive strength of the tape.

  Furthermore, a groove having a depth corresponding to the thickness of the semiconductor chip is formed on the semiconductor wafer, and when the back surface is ground and divided into individual semiconductor chips until the groove is exposed from the back surface in the grinding process, The protective tape can be easily peeled off without damaging the semiconductor chip.

  On the surface 10 of the semiconductor wafer 1 shown in FIG. 1, there are streets 11 that are a plurality of linear regions arranged in a grid at predetermined intervals. Each of the rectangular regions partitioned by the streets 11 includes A circuit is formed. Then, by cutting the street 11, each rectangular area becomes the semiconductor chip 12. Further, as shown in FIG. 2, in the present embodiment, the outer peripheral side portion 13 of the semiconductor wafer 10 is chamfered in an arc shape.

  As shown in FIG. 3, the protective tape 2 is attached to the front surface 10 of the semiconductor wafer 1 to obtain the state shown in FIGS. 4 and 5, and the back surface 14 of the semiconductor wafer 1 is exposed (protective tape attaching step). ). The protective tape 2 is of a type whose adhesive force is reduced by an external stimulus, and the external stimulus in this embodiment is ultraviolet light.

  As shown in FIGS. 4 and 5, the back surface 14 of the semiconductor wafer 1 with the transparent or translucent protective tape 2 attached to the front surface 10 is ground using, for example, the grinding apparatus 3 shown in FIG. 6. The grinding apparatus 3 includes a first cassette 300 that accommodates a plurality of unground semiconductor wafers 1 having a protective tape 2 attached to a surface thereof, and a second cassette 310 that can accommodate a plurality of ground semiconductor wafers 1. Are respectively placed on the first cassette placement area 30 and the second cassette placement area 31. In the following description, the semiconductor wafer 1 having the protective tape 2 attached to the surface may be simply referred to as the semiconductor wafer 1.

  A loading / unloading means 32 is disposed in the vicinity of the first cassette placement area 30 and the second cassette placement area 31. The carry-in / out means 32 includes a holding unit 320 that can move up and down, and the holding unit 320 enters the first cassette 300 to take out the semiconductor wafer 1 and place it on the alignment table 33.

  On the alignment table 33, the semiconductor wafer 1 is aligned at a certain position, and is then sucked by the first transfer means 340 and transferred to the chuck table 350. In the chuck table 350, the protective tape 2 side is placed and held, and the back surface 14 of the semiconductor wafer 1 is exposed upward.

  The chuck table 350 can rotate and can be revolved by the turntable 35. The turntable 35 can revolve the chuck tables 350, 351, 352, and 353 by rotating itself, and supports these chuck tables so that they can rotate.

  A wall 36 is erected from the end of the base of the grinding device 3. A pair of rails 360a and 360b are vertically arranged on the inner surface of the wall, and the support plate 362a is driven by the drive source 361a to move up and down along the rail 360a. The first grinding means 37 fixed to the upper and lower parts is driven up and down and driven by the drive source 361b to move the support plate 362b up and down along the rail 360b, so that the second grinding means 38 fixed to the support plate 362b. Is configured to move up and down.

  In the first grinding means 37, a grinding wheel 372 is attached to the tip of a rotatable spindle 370 having a vertical axis center via a mounter 371, and a grinding wheel 373 is disposed below the grinding wheel 372. It is fixed. As the grinding wheel 373, for example, a rough grinding wheel is used, and the grinding wheel 373 rotates with the rotation of the spindle 370.

  In the second grinding means 38, a grinding wheel 382 is mounted on the tip of a rotatable spindle 380 having an axial center in the vertical direction via a mounter 381, and a grinding wheel 383 is disposed below the grinding wheel 382. It is fixed. As the grinding wheel 383, for example, a grinding wheel for finish grinding is used, and the grinding wheel 383 rotates with the rotation of the spindle 380.

  When the semiconductor wafer 1 is held on the chuck table 350, the turntable 35 rotates at a predetermined angle counterclockwise so that the semiconductor wafer 1 is positioned directly below the first grinding means 37. Then, the first grinding means 37 descends and contacts the back surface of the semiconductor wafer 1 while the grinding wheel 373 rotates, whereby the back surface is roughly ground.

  Next, the turntable 35 is rotated counterclockwise by a predetermined angle so that the semiconductor wafer 1 is positioned immediately below the second grinding means 38, and the second grinding means 38 is lowered while the grinding wheel 383 is rotated. By contacting the back surface of the semiconductor wafer 1, the back surface is finish ground.

  The finish-ground semiconductor wafer 1 is positioned in the vicinity of the cleaning unit 39 by rotating the turntable 35 by a predetermined angle in the counterclockwise direction, and is then adsorbed by the second transfer unit 341 to form the cleaning unit 39. It is conveyed to the holding table 390 and held. Then, after the grinding scraps are removed by cleaning, the semiconductor wafer 1 is held in the holding unit 320 constituting the carry-in / out means 32, and the protective tape 2 is stuck on the surface while the semiconductor wafer 1 is in the second cassette. 310. The semiconductor wafers 1 whose back surfaces have been ground in this way are sequentially accommodated in the second cassette 310.

  In the semiconductor wafer 1 after the back surface grinding, as shown in FIG. 7, when the portion indicated by the two-dot chain line is ground and removed, a sharp portion 130 like a knife is formed on the outer peripheral side surface, and the semiconductor wafer Since the outer diameter of 1 is smaller than the outer diameter of the protective tape 2, the protective tape 2 protrudes to the outer peripheral side of the semiconductor wafer 1 (grinding step). The thickness of the semiconductor wafer 1 after back grinding is, for example, 100 μm or less.

  Next, as shown in FIG. 8, the semiconductor wafer 1 is turned over, and the back surface 14 of the semiconductor wafer 1 is attached to the adhesive surface 40 of the dicing tape 4. Since the adhesive surface 40 of the dicing tape 4 is attached to the back surface of the dicing frame 5, the semiconductor wafer 1 is integrated with the dicing frame 5 through the dicing tape 4 (dicing tape attaching step). The dicing tape 4 is of a type in which the adhesive strength is reduced by an external stimulus (ultraviolet rays in the present embodiment), like the protective tape 2 adhered to the surface of the semiconductor wafer 1.

  As shown in FIG. 7, since the outer diameter of the semiconductor wafer 1 is smaller than the outer diameter of the protective tape 2, the protective tape 2 and the semiconductor wafer 1 are pressed against the dicing tape 4. As shown, a protruding portion 20 protruding from the outer peripheral portion of the semiconductor wafer 1 in the protective tape 2 is bonded to the dicing tape 4 to form a bonded portion 6, and the semiconductor wafer 1 is formed by the dicing tape 4 and the protective tape 2. It may become encased.

  As shown in FIG. 10, the protective tape 2 side is irradiated with ultraviolet rays that are external stimuli (external stimulus applying step). Since the protective tape 2 is of a type in which the adhesive strength is reduced by ultraviolet rays, the adhesive strength of the protective tape 2 is reduced and is easily peeled off from the surface of the semiconductor wafer 1.

  On the other hand, since the dicing tape 4 is of a type in which the adhesive strength is reduced by receiving ultraviolet rays as in the case of the protective tape 2, the adhesive strength is reduced in the portion receiving the ultraviolet rays. That is, as shown in FIG. 11, not only the adhesive strength of the protective tape 2 is reduced but also the ultraviolet ray that is an external stimulus for the bonding portion 6 that is a portion where the protective tape 2 and the dicing tape 4 are bonded together. Passes through the protective tape 2 and also acts on the dicing tape 4 to reduce the adhesive strength of the dicing tape 4 in the bonding portion 6, so that the adhesive strength of both tapes decreases, so that the adhesive strength in the bonding portion 6 is reduced. Will decline. On the other hand, since the semiconductor wafer 1 and the dicing frame 5 shield ultraviolet rays in the portion of the dicing tape 4 where the semiconductor wafer 1 is adhered and the portion where the dicing frame 5 is adhered, the adhesive strength does not decrease. . Accordingly, the state in which the semiconductor wafer 1 and the dicing frame 5 are firmly attached to the dicing tape 4 is maintained, and the protective tape 2 is easily peeled from the semiconductor wafer 1 and the dicing tape 4.

  Thus, after reducing the adhesive force of the protective tape 2 and the adhesive force in the bonding part 6, the protective tape 2 is peeled from the surface of the semiconductor wafer 1 (protective tape peeling process). While the adhesive strength of the protective tape 2 is reduced by the irradiation of ultraviolet rays, the adhesive force in the bonding part 6 is also reduced, and further the adhesive force of the dicing tape 4 in the portion where the semiconductor wafer 1 is attached is reduced. Therefore, as shown in FIG. 12, when the protective tape 2 is peeled off, the protective tape 2 can be easily peeled off, and the semiconductor wafer 1 is not peeled off from the dicing tape 4. Therefore, the semiconductor wafer 1 can be smoothly replaced from the protective tape 2 to the dicing tape 4.

  Further, since the protective tape 2 does not pull up the dicing tape 4 when the protective tape 2 is peeled off, it is possible to prevent the semiconductor wafer from being cracked or chipped.

  In the above example, a case where a normal semiconductor wafer is pasted on a dicing tape and transferred to a dicing frame has been described, but the same applies when the semiconductor wafer is divided into semiconductor chips in a grinding process by a so-called dicing technique. . In the case of first dicing, the semiconductor wafer is already divided into semiconductor chips, so it is not necessary to dice after pasting to the dicing tape, but in order to pick up individual semiconductor chips, the dicing tape is pasted to the dicing frame. It will be transferred.

  The present invention can be used to transfer a semiconductor wafer to a dicing frame without damaging the semiconductor wafer before dicing the semiconductor wafer.

It is a perspective view which shows a semiconductor wafer. It is a front view which shows a semiconductor wafer. It is a perspective view which shows a mode that the surface of a semiconductor wafer is stuck on a protective tape. It is a perspective view which shows the semiconductor wafer by which the protective tape was stuck on the surface. It is a front view which shows the semiconductor wafer by which the protective tape was stuck on the surface. It is a perspective view which shows an example of a grinding device. It is a partially expanded front view which shows the semiconductor wafer and back surface tape after back grinding. It is a perspective view which shows a mode that the back surface of a semiconductor wafer is stuck on a dicing tape. It is a partially expanded sectional view which shows the state by which the back surface of the semiconductor wafer was stuck on the dicing tape. It is a perspective view which shows a mode that an ultraviolet-ray is irradiated to the protective tape side. It is sectional drawing which shows a mode that an ultraviolet-ray is irradiated to the protective tape side. It is a perspective view which shows a mode that a protective tape is peeled.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1: Semiconductor wafer 10: Front surface 11: Street 12: Semiconductor chip 13: Peripheral side part 14: Back surface 130: Sharp part 2: Protection tape 20: Protrusion part 3: Grinding device 30: 1st cassette mounting area 31: 1st Second cassette placement area 300: First cassette 310: Second cassette 32: Loading / unloading means 320: Holding section 33: Positioning table 340: First transport means 341: Second transport means 35: Turntable 350, 351, 352, 353: Chuck table 36: Wall portion 360a, 360b: Rail 361a, 361b: Drive source 362a, 362b: Support plate 37: First grinding means 370: Spindle 371: Mounter 372: Grinding wheel 373: Grinding wheel 38: Second grinding means 380: Spindle 381: Mounter 382: Sharp Grinding wheel 383: grinding wheel 39: cleaning means 390: holding table 4: dicing tape 40: adhesive surface 5: dicing frame 6: bonding part

Claims (6)

A method for transferring a semiconductor wafer, wherein the semiconductor wafer is transferred to a dicing frame after grinding the back surface of the semiconductor wafer having a circuit formed on the surface,
A protective tape attaching process for attaching a protective tape whose adhesive strength is reduced by external stimulation to the surface of the semiconductor wafer;
A grinding step of grinding the back surface of the semiconductor wafer by placing the protective tape side on a chuck table of a grinding device;
A dicing tape adhering step for adhering the back surface of the semiconductor wafer after grinding to a dicing tape whose adhesive force is reduced by receiving the external stimulus and integrating with the dicing frame;
An external stimulus applying step for applying the external stimulus to the protective tape side;
A method for transferring a semiconductor wafer comprising a protective tape peeling step for peeling the protective tape from the surface of the semiconductor wafer. The semiconductor wafer transfer method according to claim 1, wherein the external stimulus is ultraviolet light.   The method for transferring a semiconductor wafer according to claim 1, wherein an outer peripheral side surface of the semiconductor wafer is formed in an arc shape.   The method for transferring a semiconductor wafer according to claim 1, wherein the protective tape has a larger outer diameter than the semiconductor wafer. 5. The method for transferring a semiconductor wafer according to claim 1, wherein the semiconductor wafer is ground in the grinding step so that the thickness is 100 [mu] m or less. A groove having a depth corresponding to the thickness of the semiconductor chip is formed on the surface of the semiconductor wafer,
6. The method for transferring a semiconductor wafer according to claim 1, wherein in the grinding step, the back surface is ground and divided into individual semiconductor chips until the groove is exposed from the back surface.

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