JP2005260154A - Method of manufacturing chip - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing chips that can obtain chips of high conformity by solving the problems of rear-side chipping in wafer dicing process, contamination on the pattern-formed surface, and further, surface damage due to cutting water in water-vulnerable kinds. <P>SOLUTION: A protection sheet PS is glued S11 on a main surface of a wafer W. The wafer W is half-cut S17 from the rear surface by a dicing blade 11. After an expand sheet ES is glued S21 on the rear surface of the wafer W, the protection sheet PS is peeled off (S23). By expanding the expand sheet ES, the parts remaining in the half-cut dicing of the wafer W are cleaved S25. Chipping on the rear surface, contamination on the wafer main surface, and surface damage due to cutting water even in water-vulnerable wafers W, are all prevented. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a chip manufacturing method for manufacturing a chip such as a semiconductor device or an electronic component, and in particular, a chip that divides a wafer into individual chips by dicing while suppressing back surface chipping and device surface contamination during dicing. It relates to a manufacturing method.

  In semiconductor manufacturing processes, etc., wafers with semiconductor devices or electronic parts formed on the surface are subjected to electrical tests in the probing process and then divided into individual chips (also called dies or pellets) in the dicing process. The individual chips are then die bonded to the component base in a die bonding process. After die bonding, wire bonding is performed, and after wire bonding, resin molding is performed to obtain a finished product such as a semiconductor device or an electronic component.

  After the probing process, as shown in FIG. 9, the back surface of the wafer is adhered to an adhesive sheet S (also referred to as a dicing sheet or dicing tape) S having a thickness of about 100 μm and having an adhesive layer formed on one side thereof. Mounted on a ring-shaped frame F. In this state, the wafer W is transferred in the dicing process, between the dicing process and the die bonding process, and in the die bonding process.

  In the dicing apparatus, each chip T is cut by a diamond blade that rotates at high speed. The individual chips T that have been cut do not fall apart while being affixed to the dicing sheet S, and maintain the wafer state. Here, for convenience, the aggregate of the chips T that maintained the wafer state is also referred to as the wafer W. I will call it.

  By the way, since Si (silicon), which is a semiconductor material, is a highly brittle material, chipping is likely to occur at the edge of the processed groove during groove processing or cutting processing. This chipping has a problem that the processing quality is lowered, the diced chip T is made defective, and the processing yield is deteriorated.

In order to suppress the chipping generated at the edge of the groove in the groove processing in this dicing apparatus, a dicing apparatus and a dicing method for processing while applying vibration to the wafer W or the dicing blade have been proposed (for example, Patent Document 1). reference.).
JP 2003-318134 A

  However, if the wafer W, which is a highly brittle material, is completely cut (also referred to as a full cut) into the dicing sheet, the dicing sheet is a soft material, so when the dicing blade comes out to the dicing sheet side, the back surface of the wafer W Cracks and chipping.

  Further, the dicing sheet material is clogged in the cutting edge of the dicing blade, the grinding performance is deteriorated, and chipping is more likely to occur. The dicing sheet material clogged at the cutting edge is somewhat removed from the cutting edge (dressing effect) when the Si portion is being ground, and clogging tends to be slightly improved.

  However, when an ultra-thin wafer with a thickness of 100 μm or less to produce an ultra-thin chip to be incorporated into a smart card or ultra-thin IC card is fully cut with a dicing blade, the Si portion is smaller than the cut amount into the dicing sheet. Since the ratio is small and the dressing effect is thin, the back surface chipping is further deteriorated.

  Although the dicing method described in Patent Document 1 described above is effective in suppressing chipping on the front surface side of the wafer W, the back surface chipping in full-cut dicing of an ultra-thin wafer having a thickness of 100 μm or less has a satisfactory result. It was not obtained.

  In addition, the problem of contamination of the pattern forming surface of the wafer W and the problem of surface damage of water-sensitive products cannot be solved by the conventional chip manufacturing method using the dicing method.

  The present invention has been made in view of such circumstances, and has problems such as backside chipping in the wafer dicing process, contamination of the pattern forming surface, and surface damage due to cutting water against varieties that are vulnerable to water. It is an object of the present invention to provide a chip manufacturing method capable of solving the problem and obtaining a good chip.

  In order to achieve the above object, the present invention provides a chip manufacturing method in which a wafer having a pattern formed on a main surface is divided into individual chips, and a protective sheet is provided on the main surface of the wafer. Affixing, imaging a pattern formed on the main surface of the wafer from the back side of the wafer, aligning the wafer, and using a dicing blade, the wafer is half-cut from the back side of the wafer A step of dicing, a step of affixing an expanded sheet to the back surface of the diced wafer, a step of peeling a protective sheet affixed to the main surface of the wafer, and expanding the expanded sheet, Cleaving the portion left uncut by the half-cut dicing, Characterized in that it has.

  According to the invention of claim 1, a protective sheet is affixed to the main surface of the wafer and half-cut with a dicing blade from the back side of the wafer, and then the expanded sheet is affixed to the back side of the wafer, and then the protective sheet is peeled off, Next, by expanding the expanded sheet, the portion left uncut by the half-cut dicing of the wafer is cleaved, so that back surface chipping does not occur. Further, contamination of the main surface of the wafer is prevented, and surface damage due to cutting water does not occur even if the wafer is of a type that is weak against water.

  The invention according to claim 2 is the invention according to claim 1, wherein the protective sheet is a heat-shrinkable sheet, and an ultraviolet curable pressure-sensitive adhesive layer or a thermosetting pressure-sensitive adhesive layer is formed on one surface. In the step of peeling off the protective sheet, the protective sheet is self-peeled by heating the protective sheet or by irradiating the protective sheet with ultraviolet rays and then heating the protective sheet. Features.

  According to the invention of claim 2, the protective sheet is self-peeled by heating the protective sheet or by irradiating the protective sheet with ultraviolet rays and then heating the protective sheet, so that the wafer is damaged when the protective sheet is peeled off. There is no.

  According to a third aspect of the present invention, in the first or second aspect of the invention, in the step of attaching an expanded sheet to the back surface of the diced wafer, the expanded sheet is attached to the rear surface of the wafer, and the expanded The wafer and the frame are integrated by attaching a sheet to a ring-shaped frame.

  According to the invention of claim 3, since the wafer is integrated with the frame via the expand sheet, the wafer can be cleaved using the existing transfer device and the existing expand device.

  The invention according to claim 4 is a chip manufacturing method in which a wafer having a pattern formed on the main surface is divided into individual chips, and a protective sheet attaching step of attaching a protective sheet to the main surface of the wafer; Affixing the dicing sheet to the wafer via the protective sheet, and affixing the dicing sheet to a ring-shaped first frame disposed outside the wafer, the wafer and the first frame A first frame mounting step to be integrated; an alignment step of imaging the pattern formed on the main surface of the wafer from the back side of the wafer to align the wafer; and a back side of the wafer using a dicing blade Half-cut dicing process for half-cutting the wafer from the side, and half The dicing sheet is cut at the outer periphery of the wafer that has been diced, the wafer and the first frame are separated, and then an expanded sheet is attached to the back surface of the wafer, and the expanded sheet is formed in a ring shape. A second frame mounting step for integrating the wafer and the second frame by being affixed to the second frame, and a protective sheet peeling for peeling the protective sheet affixed to the main surface of the wafer And a cleaving step of cleaving the portion left uncut by the half-cut dicing of the wafer by expanding the expanded sheet.

  According to the invention of claim 4, back surface chipping does not occur in the dicing process, contamination of the wafer main surface is prevented, and surface damage due to cutting water is caused even for wafers that are weak against water. Does not occur. In addition, the wafer can be cleaved using an existing transfer device and an existing expanding device.

  The invention according to claim 5 is the invention according to claim 4, wherein the protective sheet is a heat-shrinkable sheet, and an ultraviolet curable pressure-sensitive adhesive layer or a thermosetting pressure-sensitive adhesive layer is formed on one surface. The dicing sheet is also a heat-shrinkable sheet, and in the step of peeling the protective sheet, the protective sheet and the dicing sheet are heated, or the protective sheet and the dicing sheet are irradiated with ultraviolet rays. Then, the protective sheet and the dicing sheet are heated to cause the protective sheet to self-peel.

  According to the invention of claim 5, since the protective sheet and the dicing sheet are heated, or the protective sheet and the dicing sheet are irradiated with ultraviolet rays and then the protective sheet and the dicing sheet are heated, the protective sheet is self-peeled. The wafer is not damaged when the protective sheet is peeled off.

  According to a sixth aspect of the invention, in the fourth or fifth aspect of the invention, the first frame and the second frame are the same type of frame.

  According to the invention of claim 6, since the wafer is mounted on the same kind of frame before dicing and after dicing, the wafer can be carried using an existing carrying device.

  As described above, according to the chip manufacturing method of the present invention, after a protective sheet is attached to the main surface of the wafer, half-cut with a dicing blade from the back side of the wafer, and then an expanded sheet is attached to the back side of the wafer. By peeling the protective sheet and then expanding the expanded sheet, the portion left uncut by the half-cut dicing of the wafer is cleaved, so that back surface chipping does not occur. In addition, contamination of the main surface of the wafer during dicing is prevented, and surface damage due to cutting water does not occur even if the wafer is of a type that is vulnerable to water.

  Hereinafter, preferred embodiments of a chip manufacturing method according to the present invention will be described in detail with reference to the accompanying drawings. In each figure, the same number or symbol is attached to the same member. In each figure, the circuit pattern formed on the wafer and the main surface of the wafer and the thickness of the sheet are described as extremely thick so that they can be easily understood, but the thickness of the wafer or sheet is actually about 100 μm, The thickness of the circuit pattern is about several μm.

  FIG. 1 is a flowchart for explaining the flow of steps of a chip manufacturing method according to the present invention. First, in order to protect the pattern surface of the wafer W on which the circuit pattern is formed on the main surface side, a protective sheet is attached to the pattern surface (step S11).

  FIG. 2 is a conceptual diagram of the protective sheet sticking machine. In the protective sheet sticking machine 20, the wafer W is sucked and supported on the suction table 21 with the circuit pattern WP facing up. A supply reel 22 is provided above the suction table 21, and the protective sheet PS fed from the supply reel 22 is taken up by the take-up reel 23 through the guide rollers 24 and 25.

  The protective sheet PS is made of a heat-shrinkable sheet material, and has an ultraviolet curable adhesive on the pasting surface, and the circuit pattern WP of the wafer W is rolled laterally while pressing the press roller 26 downward. The protective sheet PS is affixed to. Thereafter, the sheet is cut along the outer periphery of the wafer W with a cutter (not shown), and the remaining protective sheet PS is taken up on the take-up reel 23. The above is a protective sheet sticking process.

  Next, the wafer W is moved to the frame mounter 40 shown in FIG. 3 and is sucked and placed on the suction table 41 with the circuit pattern WP side facing up. Next, a rigid ring-shaped first frame F1 is sucked and placed on the outside of the wafer W.

  A supply reel 42 is provided above the suction table 41, and the dicing sheet S fed from the supply reel 42 is taken up by the take-up reel 43 through the guide rollers 44 and 45.

  The dicing sheet S is made of a heat-shrinkable sheet material, has an adhesive on the application surface, and is attached to the main surface of the wafer W by rolling it laterally while pressing the press roller 46 downward. The dicing sheet S is affixed to the protective sheet PS and the first frame F1.

  Thereafter, the cutter 47 is rotated downward while being pressed downward to cut the dicing sheet S along the vicinity of the outer periphery of the first frame F 1, and the remaining dicing sheet S is taken up by the take-up reel 43. In this state, the wafer W is mounted on the first frame F1 through the dicing sheet S and integrated (step S13). This is the first frame mounting process.

  A large number of wafers W integrated with the first frame F1 are stored in a cassette and put into a dicing apparatus. In the dicing apparatus, first, as shown in FIG. 4, the wafer W is adsorbed on the Xθ table 12 through the dicing sheet S and the protective sheet PS, and the first frame F1 is fixed to the Xθ table 12. Adsorbed to the frame clamper 12A.

  In this state, the circuit pattern WP formed on the main surface of the wafer is imaged from the back surface by the observation optical system 15 having the infrared illumination device and the infrared camera, and is aligned from the back surface by an image processing device and an alignment device (not shown). (Step S15). Since alignment from the back surface of the wafer W using infrared IR is already well known, detailed description is omitted.

  After the alignment is completed, as shown in FIG. 5, the wafer W is half-cut diced with a small amount left uncut by the dicing blade 11 attached to the high-frequency motor built-in air bearing spindle 13 and rotating at high speed (step S17). .

  At this time, the uncut thickness of the wafer W is less than half of the wafer thickness, and 30 μm to 50 μm is preferable including the thickness of the circuit pattern WP. If it is thinner than 30 μm, the wafer W may be damaged in the step of applying the next expanded sheet. On the other hand, if the thickness is larger than 50 μm, the wafer W is not cleaved well in the subsequent cleaving step.

  The dicing blade 11 used has a diamond abrasive grain size of # 4,000 to # 6,000, and a thin one having a thickness of 15 μm to 20 μm. This is intended to reduce chipping and grinding powder. It is also effective for dicing an ultra-thin wafer to use a blade having a V-shaped cutting edge and a blade having a plurality of notches formed at the tip.

  The wafer W that has been half-cut diced in step S <b> 17 is then subjected to a frame replacement process (second frame mounting process) in which the front and back are reversed to be replaced with another frame (second frame).

  FIG. 6 shows the frame replacement device 50. In the frame replacement process, first, as shown in FIG. 6A, the wafer W is sucked and placed on the suction table 51 with the back side up, and the first frame F1 is a frame clamper 51A provided on the suction table 51. To be adsorbed. In this state, the cutter 57 descends and makes one round along the outer periphery of the wafer W, and the dicing sheet S is cut. Thereby, the wafer W is separated from the first frame (step S19).

Next, as shown in FIG. 6B, the suction table 51 is lifted while the wafer W is sucked and placed, and the upper surface of the second frame F <b> 2 held by the frame holder 59 and the rear surface of the wafer W are the same. Position it so that it is at the height.

  On the other hand, a supply reel 52 is provided above the suction table 51 so that an expanded sheet ES, which is a second adhesive sheet fed out from the supply reel 52, is taken up by the take-up reel 53 via the guide rollers 54 and 55. It has become.

  The expand sheet ES has an ultraviolet curable adhesive on the pasting surface, and rolls in the lateral direction while pressing the press roller 56 downward, thereby forming the back surface of the wafer W and the upper surface of the second frame F2. Expand sheet ES is affixed.

  Thereafter, the cutter 57 is rotated once while being pressed against the expanded sheet ES to cut the expanded sheet ES along the vicinity of the outer periphery of the second frame F <b> 2, and the remaining expanded sheet ES is taken up by the take-up reel 23. In this state, the wafer W is reversed and attached to the second frame F2 via the expanded sheet ES, and is integrated (step S21). This is the second frame mounting process (frame replacement process).

  Note that it is preferable that the first frame F1 and the second frame F2 are the same type of frame because the frame can be transported between the dicing apparatus and the die bonder and in the die bonder using an existing transport apparatus.

  Next, the wafer W attached to the second frame F2 is transferred to the peeling device 60 shown in FIG. In the peeling apparatus 60, first, as shown in FIG. 7A, the wafer W is placed on the suction table 61 with the protective sheet PS and the dicing sheet S side up and the expanded sheet ES attached to the back side down. The second frame F2 is sucked and placed on a frame clamper 61A provided on the suction table 61.

  Next, ultraviolet rays UV are irradiated from the dicing sheet S side on the main surface side of the wafer W by the ultraviolet irradiation device 62. Since the ultraviolet transmissive resin is used for the dicing sheet S and the protective sheet PS, the ultraviolet curable pressure-sensitive adhesive layer formed on the protective sheet PS is cured, and the adhesive force with the wafer W is reduced.

  Next, as shown in FIG. 7B, the dicing sheet S and the protective sheet PS on the main surface side of the wafer W are heated by hot air blown from the hot air nozzle 63. Since the protective sheet PS and the dicing sheet S are heat-shrinkable sheet materials, the entire sheet shrinks, curves on the curl, and self-separates from the main surface of the wafer W. This is a protective sheet peeling process (step S23).

  As a result, as shown in FIG. 7C, the protective sheet PS and the dicing sheet S attached to the circuit pattern WP side are peeled off, and the wafer W is expanded on the back side with the circuit pattern WP side up. Is pasted and only integrated with the second frame F2.

  In this state, a large number of wafers W are stored in a cassette and put into a die bonder. The die bonder irradiates ultraviolet rays from the expanded sheet ES side to reduce the adhesive strength of the ultraviolet curable adhesive material formed on the expanded sheet ES. Next, the expanding sheet 70 is stretched by the expanding apparatus 70 shown in FIG. 8 to cleave the uncut portion of the wafer W half-cut by the dicing apparatus, and the cleaving process is performed to increase the interval between the chips. .

  In the cleavage step, as shown in FIG. 8, the wafer W is first placed on the suction table 71 without being sucked, and the second frame F2 is sucked and held on the frame clamper 71A. Next, the suction table 71 is raised, and the expanded sheet ES is stretched radially. As a result, the portion left uncut by the half-cut dicing of the wafer W is cleaved and the individual chip interval is increased (step S25).

  Next, each chip T is picked up one by one with a collet and die-bonded (chip mounted) to a package substrate such as a lead frame.

  The above is the process flow of the chip manufacturing method according to the embodiment of the present invention. As described above, according to the present invention, half-cut dicing is performed by slightly cutting off the wafer W, and the expanded sheet ES attached to the dicing groove side of the wafer W is expanded. A portion having a thickness of ˜50 μm is easily cleaved and separated into individual chips T, and no chipping occurs on the back surface.

  In addition, since half-cut dicing is performed with the protective sheet PS attached to the main surface of the wafer W, the circuit pattern is not contaminated, and even a wafer W that is vulnerable to water is subject to surface damage. There is no.

  Furthermore, since the wafer W is reversed and attached to another frame after dicing, it is possible to carry the frame within the dicing apparatus, between the dicing apparatus and the die bonder, and within the die bonder using an existing conveying apparatus.

  In the above-described embodiment, the dicing sheet S and the expanded sheet ES are different from each other. However, since the dicing sheet S generally has a good extensibility, the expanded sheet ES is used. A dicing sheet S may be used instead.

  Further, although the dicing sheet S is pasted on the protective sheet PS side and mounted on the first frame F1, it may be handled as a single wafer with a protective sheet without mounting on the frame F1. In addition, when the expanded sheet is attached, the expanded sheet 70 may be mounted alone without being mounted on the frame F2.

  Further, although the protective sheet PS is provided with an ultraviolet curable adhesive, a protective sheet PS with a thermosetting adhesive may be used. In this case, when the protective sheet PS is peeled off, it is not necessary to irradiate the protective sheet PS with ultraviolet UV, and it is only necessary to heat the protective sheet PS. The heating of the protective sheet PS is not limited to hot air injection, but may be performed by a contact conduction method such as contacting a heating plate or a radiation method.

The flowchart showing the process of the chip manufacturing method according to the present invention Conceptual diagram explaining the protective sheet application process Conceptual diagram explaining the first frame mounting process Conceptual diagram explaining the backside alignment process Conceptual diagram explaining half-cut dicing process Conceptual diagram illustrating the second frame mounting process Conceptual diagram explaining the protective sheet peeling process Conceptual diagram explaining the cleavage process A perspective view showing a wafer mounted on a conventional frame

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Dicing apparatus, 11 ... Dicing blade, 20 ... Protection sheet sticking machine, 40 ... Frame mounter, 50 ... Frame pasting apparatus, 60 ... Peeling apparatus, 70 ... Expanding apparatus, ES ... Expanding sheet, F1 ... 1st frame F2 ... second frame, IR ... infrared, PS ... protective sheet, S ... dicing sheet, T ... chip, UV ... ultraviolet, W ... wafer, WP ... circuit pattern (pattern)

Claims (6)

In a chip manufacturing method in which a wafer with a pattern formed on the main surface is divided into individual chips,
Attaching a protective sheet to the main surface of the wafer;
Imaging the pattern formed on the main surface of the wafer from the back side of the wafer, and aligning the wafer;
Using a dicing blade, half-cut dicing the wafer from the back side of the wafer,
Attaching an expanded sheet to the backside of the diced wafer;
Peeling the protective sheet affixed to the main surface of the wafer;
And a step of cleaving a portion of the wafer left uncut by the half-cut dicing by expanding the expanded sheet. The protective sheet is a heat-shrinkable sheet, and an ultraviolet curable pressure-sensitive adhesive layer or a thermosetting pressure-sensitive adhesive layer is formed on one surface,
In the step of peeling off the protective sheet, the protective sheet is self-peeled by heating the protective sheet or by irradiating the protective sheet with ultraviolet rays and then heating the protective sheet. The chip manufacturing method according to claim 1.   In the step of attaching the expanded sheet to the back surface of the diced wafer, the expanded sheet is attached to the back surface of the wafer, and the expanded sheet is attached to a ring-shaped frame so that the wafer and the frame are integrated. The chip manufacturing method according to claim 1, wherein: In a chip manufacturing method in which a wafer with a pattern formed on the main surface is divided into individual chips,
A protective sheet attaching step of attaching a protective sheet to the main surface of the wafer;
Affixing the dicing sheet to the wafer via the protective sheet, and affixing the dicing sheet to a ring-shaped first frame disposed outside the wafer, thereby allowing the wafer, the first frame, A first frame mounting step for integrating
Aligning the wafer by imaging the pattern formed on the main surface of the wafer from the back side of the wafer,
Using a dicing blade, a half-cut dicing step of half-cutting the wafer from the back side of the wafer,
The dicing sheet is cut at the outer periphery of the wafer that has been half-cut diced, the wafer and the first frame are separated, and then an expanded sheet is attached to the back surface of the wafer, and the expanded sheet is A second frame mounting step of integrating the wafer and the second frame by attaching to a ring-shaped second frame;
A protective sheet peeling step for peeling off the protective sheet affixed to the main surface of the wafer; and a cleaving step for cleaving a portion left uncut by the half-cut dicing of the wafer by expanding the expanded sheet; A chip manufacturing method characterized by comprising: The protective sheet is a heat-shrinkable sheet, and an ultraviolet curable pressure-sensitive adhesive layer or a thermosetting pressure-sensitive adhesive layer is formed on one surface,
The dicing sheet is also a heat shrinkable sheet,
In the step of peeling off the protective sheet, by heating the protective sheet and the dicing sheet, or by irradiating the protective sheet and the dicing sheet with ultraviolet rays and then heating the protective sheet and the dicing sheet, The chip manufacturing method according to claim 4, wherein the protective sheet is self-peeled.   The chip manufacturing method according to claim 4, wherein the first frame and the second frame are the same type of frame.

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