JP2005129742A - Dicing blade and dicing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a dicing blade that can satisfactorily dice a wafer even when a low-dielectric constant interlayer insulating film (Low-k film) is laminated upon the wafer, and to provide a dicing method. <P>SOLUTION: In the dicing blade 10, the grain size and degree of concentration of abrasive grains are respectively adjusted to #4,000-6,000 and 60-90, and a metal softer than nickel is used as a binding material. The front end of the outer peripheral section of the blade is formed in a V-shape over the whole circumference and, at the same time, a plurality of V-shaped notches 10B are formed in the outer peripheral section. In the dicing method, the wafer is incompletely cut by forming a V-shaped groove from the surface side of the wafer by using the dicing blade 10. Then the wafer is completely cut by cutting the uncut portion left by the incomplete cutting with a dicing blade thinner than the dicing blade 10. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a dicing blade and a dicing method, and more particularly to a dicing blade and a dicing method for dividing a wafer such as a semiconductor device or an electronic component into individual chips.

  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. 8, the back surface of the wafer is attached to an adhesive sheet S (also called a dicing sheet or dicing tape) S having a thickness of about 100 μm with an adhesive layer formed on one side, and a rigid ring. Is mounted on a frame F. In this state, the wafer W is conveyed in the dicing process, between the dicing process and the die bonding process, and in the die bonding process.

  In the dicing process, a dicing apparatus that cuts the wafer by inserting grinding grooves into the wafer W with a thin grindstone called a dicing blade is used. The dicing blade is obtained by electrodepositing fine diamond abrasive grains with Ni, and an extremely thin one having a thickness of about 10 μm to 30 μm is used.

  The dicing blade is rotated at a high speed of 30,000 to 60,000 rpm and cut into the wafer W to completely cut the wafer W (full cut). At this time, since the adhesive sheet S stuck on the back surface of the wafer W is cut only about 10 μm from the front surface, the wafer W is cut into individual chips T, but the individual chips T are separated. In other words, since the arrangement of the chips T is not collapsed, the wafer state is maintained as a whole.

  However, in the case of grinding with this dicing blade, since the wafer W is a highly brittle material, it becomes brittle mode processing, and chipping occurs on the front and back surfaces of the wafer W, and this chipping is a factor that deteriorates the performance of the divided chips T. It was.

On the other hand, in order to improve the general function of the dicing blade, a dicing blade that has a plurality of grooves formed radially on both the front and back sides of the dicing blade to improve the supply of cutting water to the processing part and the removal of chips Has been proposed (see, for example, Patent Document 1).
JP-A-6-188308

  However, in recent years, circuit wiring has increasingly shrunk in order to reduce the size and capacity of ICs, and the wiring material has been changed from conventional Al wiring to Cu wiring, and a low dielectric constant interlayer insulating film (Low-k film) is used. It has become.

  When the wafer on which the low-k film is laminated is diced, there is a problem that the film is turned up or the dicing blade is easily clogged with the film material, and the dicing blade described in Patent Document 1 is used. However, good dicing could not be performed.

  The present invention has been made in view of such circumstances, and a dicing blade and a dicing method capable of performing good dicing even on a wafer on which a low dielectric constant interlayer insulating film (Low-k film) is laminated. The purpose is to provide.

  In order to achieve the above object, the present invention is a dicing blade that divides a wafer into individual chips, wherein the dicing blade has a grain size of # 4000 to # 6000. Thus, the concentration of abrasive grains is 60 to 90, a softer metal than nickel is used for the binder, the outer peripheral tip has a V shape, and a plurality of V-shaped notches are formed in the outer peripheral portion. It is characterized by being.

  According to the dicing blade of the present invention, since the grain size of the abrasive grains is high, the chipping is small, the concentration degree of the abrasive grains is low, and the sharpness is good because of the soft bond, and the tip of the outer periphery of the dicing blade has a V shape. In addition, since a plurality of V-shaped notches are formed on the outer peripheral portion, chipping is further reduced, adhesion of chips to the blade tip portion is reduced, and a sharpness maintaining effect is achieved, and cutting to the processing portion is performed. Water supply is promoted, cutting load is reduced, and chip removal function is improved.

  Further, the dicing blade of the present invention has an additional requirement that the tip angle of the outer peripheral portion forming the V shape is 30 ° to 50 °, and the angle of the bottom of the V-shaped notch is 80 ° to 100 °. Is an additional requirement.

  According to this, since the tip of the blade is an acute angle, the surface chipping during dicing is reduced and the various film materials that are stacked are prevented from being turned over, and the shoulder of the V-shaped notch has a wide angle with the outer periphery of the blade. As a result, the chipping caused to the wafer by the shoulder of the V-shaped notch is further reduced.

  According to another aspect of the present invention, there is provided a dicing method for dividing a wafer into individual chips in order to achieve the above object, using the dicing blade according to any one of the first, second, and third aspects. A grinding groove is formed from the front surface side of the wafer to incompletely cut the first wafer (first processing), and then another portion dicing from the incomplete cutting using another dicing blade thinner than the dicing blade is used. The wafer is completely cut by cutting (second processing).

  According to the present invention, a V-groove is formed on the front surface side of the wafer with a blade having a V-shaped outer peripheral tip and a plurality of V-shaped notches formed in the outer peripheral portion, and the bottom of the V-groove is connected to another blade. Therefore, the wafer can be completely cut in a state where chipping on the front side of the wafer is suppressed.

  Also. The dicing method of the present invention uses a dicing apparatus having two spindles, a spindle for mounting a dicing blade for performing the first processing and a spindle for mounting a dicing blade for performing the second processing. It is an additional requirement that processing be performed simultaneously with a slight time difference with respect to the first processing, or with a delay of one line or a plurality of lines. Further, the wafer has a low dielectric constant interlayer insulating film (Low) on the surface side. -K film) is a laminated wafer.

  According to this, since the V-groove processing on the front surface side of the wafer and the cutting processing performed on the bottom of the V-groove proceed simultaneously with a predetermined time difference, the dicing time is greatly reduced. Further, in a wafer in which a low dielectric constant interlayer insulating film (Low-k film) is laminated on the surface side, film peeling and clogging of the blade due to the film are prevented, and good dicing can be performed.

  As described above, according to the dicing blade and the dicing method of the present invention, chipping generated on the wafer is reduced, adhesion of chips to the blade tip portion is reduced, and a sharpness maintaining effect is obtained, and the processing portion is also treated. The cutting water supply is promoted to reduce the cutting load, and at the same time the chip removal function is improved, so even a wafer on which a low dielectric constant interlayer insulating film (Low-k film) is laminated has good dicing. It can be performed.

  Preferred embodiments of a dicing blade and a dicing method according to the present invention will be described below in detail with reference to the accompanying drawings. In each figure, the same number or symbol is attached to the same member.

  FIG. 1 is a plan view showing a dicing blade according to an embodiment of the present invention, FIG. 2 is a side sectional view, and FIG. 3 is a perspective view showing a main part. As shown in FIGS. 1, 2, and 3, the dicing blade 10 includes a flange 10C made of aluminum (Al) and a cutting blade 10A.

  The cutting blade 10A is electroformed using an electroplating technique with diamond abrasive grains on one end face of the flange 10C and an alloy of nickel (Ni) and a softer metal than nickel such as copper (Cu) as a binder. After fixing the diamond abrasive grains, the flange portion 10D of the flange 10C (the portion indicated by the two-dot chain line in FIG. 2) is removed by etching to form the blade portion.

  By using a metal softer than normal nickel for the binder, the self-generated action of the abrasive grains is activated and the sharpness is maintained.

As the diamond abrasive grains, fine abrasive grains having a grain size of # 4000 to # 6000 are used to reduce chipping during wafer cutting. Further, the degree of concentration representing the ratio of the abrasive grains in the cutting blade 10A is based on the weight unit of diamond, and 4.4ct / cm ^{3 is set} to 100, so that the value is four times the volume%. However, in this embodiment, it is 60 to 90.

  When the degree of concentration is less than 60, the number of abrasive grains is insufficient and the sharpness is lowered, and when it is greater than 90, pockets formed between the abrasive grains are too small, and the supply of cutting water and the removal of chips are poor. The sharpness is also reduced. In the present embodiment, the degree of concentration is preferably 60 to 90, but more preferably 70 to 80.

  A cutting blade 10A having an outer diameter of about 50 mm and a thickness of about 30 μm to 100 μm is used corresponding to the width of the street K of the wafer W.

  The cutting blade tip of the cutting blade 10A is trued or etched with a diamond dresser to form a V shape with a tip angle of 40 ° over the entire tip (outer periphery) as shown in FIG.

  The tip angle of the V shape is preferably in the range of 30 ° to 50 °, but is 40 ° in the present embodiment. If the tip angle is sharper than 30 °, the chipping reduction effect due to the V-shaped effect at the time of cutting is poor, and if the tip angle is obtuse than 50 °, the amount of uncut portion is reduced in V-groove machining within a predetermined street width. Can not do it.

  Further, as shown in FIG. 1, a plurality of V-shaped notches 10B, 10B,... Are formed at equal intervals on the circumference at the tip (outer periphery) of the cutting blade 10A. The bottom part of the V-shaped notch 10B and the connection part between the shoulder part and the outer circumference of the V-shaped notch 10B are each gently connected by an arc.

  The angle of the bottom of the V-shaped notch 10B, that is, the V-shaped angle θ is preferably 80 ° to 100 °, and more preferably 85 ° to 95 °. When the V-shaped angle θ is smaller than 80 °, the angle of the connecting portion between the V-shaped notch 10B and the outer peripheral portion becomes tight, and chipping is likely to occur during cutting. Moreover, when larger than 100 degrees, the conveyance effect and cutting waste discharge effect of cutting water will fall.

  The V-shaped notch 10B has an opening width L of about 200 μm and a depth H of about 100 μm. Also, if the number of V-shaped notches 10B is too large or too small, good cutting results cannot be obtained, and 12 to 20 are preferable.

  As a method for forming the V-shaped notch 10B, the V-shaped notch 10B may be formed by etching on the outer peripheral portion after forming the blade portion of the cutting blade 10A, but the flange portion 10D of the flange 10C of the dicing blade 10 ( A V-shaped notch is formed in advance on the outer periphery of the portion (shown by a two-dot chain line in FIG. 2), and diamond abrasive grains are electrodeposited on the end face of the flange 10C to have a V-shaped notch 10B. A cutting blade 10A is formed. Thereafter, the flange portion 10D of the flange 10C is removed by etching by the protruding amount of the cutting blade 10A, and a V shape having a tip angle of 40 ° is formed over the entire circumference.

  Next, an embodiment of the dicing method according to the present invention will be described. The wafer W is extremely thin with a thickness of 100 μm or less, and is mounted on a frame F via an adhesive sheet S and supplied to a dicing apparatus as shown in FIG.

  FIG. 4 is a perspective view showing the appearance of the dicing apparatus. The dicing apparatus 100 includes a load port 60 that transfers a cassette containing a plurality of wafers W to / from an external apparatus, a transport unit 50 that has a suction unit 51 and transports the wafer W to each part of the apparatus, The imaging unit 81 for imaging the surface, the processing unit 20, a spinner 40 for cleaning and drying the processed wafer W, a controller 90 for controlling the operation of each unit of the apparatus, and the like.

  The processing unit 20 is provided with an air bearing spindle 22 with a built-in high-frequency motor, which is disposed so as to be opposed to each other and to which a dicing blade 10 or 21 is attached, and is at 30,000 rpm to 60,000 rpm. While rotating at high speed, index feed in the Y direction and cut feed in the Z direction are performed independently of each other. In addition, the work table 23 on which the wafer W is sucked and mounted is ground and fed in the X direction in the figure by the movement of the X table 30.

  FIG. 5 is a conceptual diagram illustrating an embodiment according to the dicing method of the present invention. Of the two spindles 22 arranged opposite to each other in the dicing apparatus 100, a front-side (left side in FIG. 5) spindle 22A is attached with a V-shaped dicing blade 10 and a back side (right side in FIG. 5) spindle. An extremely thin dicing blade 21 is attached to 22B.

  The tip V-shaped dicing blade 10 is rotated at 50,000 to 55,000 rpm. The ultra-thin dicing blade 21 is also an electroformed blade of diamond abrasive grains having a particle size of # 4000 to # 6000 (preferably # 5000), an outer diameter of about 50 mm, a blade thickness of 10 μm to 30 μm (preferably 15 μm to 20 μm), The blade tip protrusion amount is 300 μm and the concentration of abrasive grains is 70-80, which is lower than the standard, and is rotated at 50,000 rpm to 55,000 rpm.

  Note that if the particle size of the ultra-thin dicing blade 21 is coarser than # 4000, the back surface chipping of the wafer W occurs more than an allowable value, and if it is finer than # 6000, the grinding load is too large and dicing cannot be performed. Further, if the blade thickness is less than 10 μm, the rigidity is weak and breaks immediately and is not practical. If the blade thickness is more than 30 μm, it may protrude from the V-groove and is not suitable.

  In the dicing method of the present invention, first, as shown in FIG. 5 (a), with the back surface of the wafer W attached to the adhesive sheet S, the front ends of the plurality of pattern surfaces formed on the main surface of the wafer W A V-groove G is formed with a V-shaped dicing blade 10.

FIG. 6 shows a state in which the V groove G is formed. In the V-groove grinding, as shown in FIG. 6, cutting is performed from the surface side of the wafer W while supplying the grinding liquid from the nozzles 24, 24 provided with the V-shaped dicing blade 10 interposed therebetween, and incomplete cutting is performed. . As the grinding fluid, pure water bubbling CO ₂ is used.

  The formed V-groove G is as shown in part A of FIG. FIG. 7 is an enlarged view of the A portion. As shown in the figure, the V groove G is left uncut from the back surface of the wafer W by the thickness of D. This uncut amount D is 5 μm to 30 μm, preferably 10 μm to 25 μm, and more preferably 15 μm to 20 μm. The grinding speed at this time was 40 mm / sec when the wafer W was Si.

  After several lines of this V-groove formation, as shown in FIG. 5B, the bottom of the first V-groove G is fully cut by cutting about 10 μm into the adhesive sheet S using an extremely thin dicing blade 21. Dicing (complete cutting) is performed. The grinding speed at this time was also 40 mm / sec.

  When the uncut amount D is 5 μm or less, cracks that reach the back surface occur in places on the wafer W when the V-groove is formed. In addition, when the remaining cutting amount D is 30 μm or more, the dicing must be performed at an extremely low grinding speed because the grinding load is too large at the time of full-cut dicing with an ultra-thin blade of particle size # 5000 performed after the V-groove formation. This is not possible and is not practical from the viewpoint of throughput.

  As described above, since the V-groove formation and the full-cut dicing have the same grinding speed, the preceding V-groove formation and the subsequent full-cut dicing can be performed simultaneously. In this way, as shown in FIG. 5C, V-groove formation and full-cut dicing proceed sequentially, and when the processing of all the streets K is completed, the wafer W rotates 90 ° and goes straight to the previous streets K. V-groove formation and full cut dicing of street K is performed.

  Thus, since the V-groove G is first formed on the pattern surface side of the wafer W by the dicing blade 10 having the tip V shape, it can be used for various device films. For example, even in the case of a film that tends to generate a peeling such as a low w-k film or a polyimide-based thick film device having a thickness of 10 μm to 20 μm, chipping and film peeling are reduced, and the film thickness and film quality depend on the device. Dicing that is not performed is possible.

  Further, when full-cut dicing is performed on the bottom of the V-groove G using the ultra-thin dicing blade 21, the grinding water easily flows into the deep V-groove G, so that the grinding water can be supplied to the grinding point well, and the wafer Effects such as W back surface chipping and reduction of clogging of the film at the tip of the dicing blade 10 are brought about.

  In this way, a large number of chips T, T,... Are divided from the wafer W. . Normally, when dicing a Si wafer with an ultrathin blade of # 5000, the grinding speed is highest at 20 mm / sec. However, in the embodiment of the present invention, the uncut amount D is extremely small, from 5 μm to 30 μm. Dicing can be performed at a speed of 40 mm / sec, and chipping on the back surface is also reduced.

  In this way, half-cut dicing of the wafer W with the V-shaped notched dicing blade 10 at the tip V shape prevents the film laminated on the surface side of the wafer W from being turned up, chipping is reduced, and clogging is prevented. , Chip removal, suitable supply of cutting water, and the like.

  In addition, by fully cutting the bottom of the V-groove with a high-graded, soft-bond, ultra-thin electroformed dicing blade 21, it is possible to perform constant-speed machining with V-groove machining with a reduction in back surface chipping, with a predetermined time delay Simultaneous processing with V-groove processing is possible, and an increase in dicing time can be suppressed.

  Thus, the dicing method of the present invention is particularly effective for a wafer W having a low wk film laminated on the surface side, a wafer W having a thickness of 100 μm or less used for a smart card, a thin IC card, and the like. It is.

  In the above-described embodiment, the dicing blade 10 is described as the type with the flange 10C. However, the present invention is not limited to this, and may be a washer type blade that is not integrated with the flange. Also, the abrasive grains used are not limited to diamond abrasive grains, but CBN (cubic, boron, nitride) abrasive grains may be used, and not only electroformed blades but also ordinary metal bond blades and resin bond blades. May be.

The top view showing the dicing blade concerning an embodiment of the invention 1 is a side sectional view showing a dicing blade according to an embodiment of the present invention. The principal part perspective view of the dicing blade which concerns on embodiment of this invention Perspective view showing a dicing apparatus The conceptual diagram showing the dicing method which concerns on embodiment of this invention Cross-sectional view showing the machining state Sectional view showing the processed V-groove Perspective view showing wafer mounted on frame

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10, 21 ... Dicing blade, 10A ... Cutting blade, 10B ... V-shaped notch, 10C ... Flange, 22, 22A, 22B ... Spindle, 100 ... Dicing apparatus, F ... Frame, S ... Adhesive sheet, T ... Tip, W ... wafer

Claims (6)

A dicing blade for dividing a wafer into individual chips, and a thin dicing blade having a blade thickness of 100 μm or less,
The dicing blade has an abrasive grain size of # 4000 to # 6000, an abrasive grain concentration of 60 to 90, a softer metal than nickel is used for the binder, and the outer peripheral tip has a V shape. A dicing blade characterized in that a plurality of V-shaped notches are formed in the outer peripheral portion.   2. The dicing blade according to claim 1, wherein a tip angle of the outer peripheral portion forming the V shape is 30 ° to 50 °.   The dicing blade according to claim 1, wherein an angle of a bottom portion of the V-shaped notch is 80 ° to 100 °. In a dicing method for dividing a wafer into individual chips,
Using the dicing blade according to any one of claims 1, 2, or 3, a grinding groove is formed from the surface side of the wafer to cut the wafer incompletely (first processing),
Next, using another dicing blade thinner than the dicing blade, the wafer is completely cut by cutting (second processing) a portion left uncut by the incomplete cutting. . Using a dicing apparatus having two spindles, a spindle for mounting the dicing blade for performing the first processing and a spindle for mounting the dicing blade for performing the second processing,
The dicing method according to claim 4, wherein the second processing is performed simultaneously with a slight time difference from the first processing, or with a delay of one line or a plurality of lines.   6. The dicing method according to claim 4, wherein the wafer is a wafer in which a low dielectric constant interlayer insulating film (Low-k film) is laminated on a surface side.

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