JP2005093503A - Dicing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a dicing method wherein a dicing guide is not required to get large in width, and a blade is hardly affected by adhesive material applied on the surface of a dicing tape even when it cuts into the dicing tape. <P>SOLUTION: A wafer is diced with a first blade 8A of high processing accuracy so far as only a very small amount of a region is left uncut. Thereafter, a second blade 8B mainly used for cutting the dicing tape 9 is tilted at an angle of 5° or below, preferably 3° with a direction perpendicular to a wafer so as not to come into contact with a first diced plane, and the uncut region and the upper part of the dicing tape are cut off by the second blade 8B. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a light emitting diode array, and more particularly to a high density light emitting diode array suitable for an LED printer.

    FIG. 4 is an enlarged view of a part of a semiconductor wafer on which a chip pattern of a general light emitting diode array used for a printer head of an LED printer is formed. Each light emitting diode adjacent to each other with a dicing guide 4 as a boundary. An array chip 1 is shown. FIG. 5 is an explanatory diagram for performing dicing along the dicing guide 4 in FIG.

  In dicing a light-emitting diode array used in an LED printer, the direction perpendicular to the arrangement direction of the light-emitting dots (light-emitting diodes) 2 (hereinafter referred to as the Y-axis) that serves as the chip mating surface is important. In order to improve (on the basis of the chip length), the cutting shape is required to be a complete vertical shape or an inverted trapezoidal shape as shown in FIG. In order to obtain a complete vertical shape or an inverted trapezoidal shape as shown in FIG. 5, it is necessary to provide the dicing blade 8 with a slight inclination θ1 (0.5 to 2 °) with respect to the vertical direction of the wafer. . Further, since processing is required for each chip, it is necessary to dice twice for one dicing guide formed between adjacent chips.

  On the other hand, the dicing guide 7 in the direction parallel to the arrangement direction of the light emitting dots 2 (hereinafter referred to as the X axis) has a large dimensional tolerance and may be standard dicing.

  In general, the most important factor in dicing a light-emitting diode array is that the occurrence of chips 12 and cracks 13 as shown in FIG. 6 must be suppressed so as not to deteriorate the characteristics of the light-emitting dots 2 when dicing along the Y axis. is there.

  On the other hand, since the design tolerance is large for the X axis, the problem of chipping and cracking can be avoided by design.

  Particularly in the case of Y-axis dicing, in the case of a high-density light emitting diode array such as 600 DPI and 1200 DPI, the uncut dicing amount D1 (distance between the outermost light emitting dot 2 and the dicing surface (chip cutting surface) 3a) is 4 μm or less. Since it is very small, suppression of chipping and cracking is the most important issue.

  Therefore, conventionally, the following means have been taken to suppress chipping and cracking.

   (1) Reduce the diameter of diamond particles at the blade tip.

   (2) Increase the rotation speed during cutting.

   (3) Reduce the cutting speed.

  However, in any of the above means (1) to (3), when the dicing tape 9 is cut, the adhesive material of the adhesive layer 10 on the surface of the dicing tape 9 tends to clog the blade. Therefore, even if good dicing with little chipping and cracking can be performed at the beginning of dicing, clogging of the adhesive material to the blade gradually proceeds by repeatedly dicing, and as a result, chipping and cracking increase. Defects occur.

  Therefore, conventionally, a method of performing dicing by a half cut in the vertical direction and a full cut from the oblique direction is known (see, for example, Patent Document 1).

According to this method, in the full cut dicing from the oblique direction, the cut position accuracy is defined by the vertical dicing, so that a certain amount of cut position deviation can be allowed. Further, in the full-cut dicing from the oblique direction, even if the dicing blade is clogged by cutting the dicing tape at the end, the surface of the LED array is not cut during the full-cut dicing (surface side Therefore, chipping and cracks do not reach the surface of the LED array.
Japanese Patent Laid-Open No. 5-121544

  However, in Patent Document 1, full-cut dicing is performed by a dicing blade that is relatively inclined to about 8 degrees with respect to the vertical plane. For this reason, it is necessary to ensure a large dicing guide width.

  Accordingly, an object of the present invention is to provide a dicing method that solves the above-described problems, does not require a large dicing guide width, and is not affected by the adhesive material on the surface of the dicing tape even when the dicing tape is cut. .

  In order to achieve the above object, the present invention is configured as follows.

  The dicing method according to the invention of claim 1 is a method of dicing a light emitting diode from a wafer having a large number of light emitting diodes formed and having a dicing tape attached to the back surface. Dicing is performed up to the area to be cut, and then, with a second blade mainly for cutting dicing tape, it is 5 ° or less, preferably about 3 ° with respect to the vertical direction of the wafer so as not to touch the first dicing surface. It is made to incline at the angle of and cuts the above-mentioned uncut area and the upper part of the dicing tape.

  A dicing method according to a second aspect of the present invention is a method of dicing a light emitting diode array along a dicing guide formed between the arrays, from a wafer having a light emitting diode array formed and a dicing tape attached to the back surface. The first blade with high processing accuracy is diced to the area where the wafer is slightly cut, and then the second blade mainly for cutting the dicing tape is used to prevent the wafer from touching the first dicing surface. It is characterized in that it is inclined at an angle of 5 ° or less, preferably about 3 ° with respect to the vertical direction, and the uncut region and the upper part of the dicing tape are cut.

  According to a third aspect of the present invention, in the dicing method according to the first or second aspect, the wafer is cut by about 10 to 50 μm with the first blade having a high processing accuracy.

  According to a fourth aspect of the present invention, in the dicing method according to any one of the first to third aspects, a blade having a relatively fine diamond particle diameter at the tip of the blade is used as the first blade, and the diameter is 1 to 2 mm / second. Further, the second blade is characterized in that a blade having a relatively coarse diamond particle diameter is used as the second blade and high-speed dicing is performed at 5 to 10 mm / second.

  According to a fifth aspect of the present invention, in the dicing method according to any one of the second to fourth aspects, a single dicing guide is diced twice at two locations in the width direction and cut into an inverted trapezoidal shape. Features.

  According to a sixth aspect of the present invention, in the dicing method according to the fifth aspect, the first blade is inclined by about 1 ° with respect to the vertical direction of the wafer.

<Key points of the invention>
In the present invention, for example, in the Y-axis dicing that is important for dicing the light-emitting diode array, a dicing apparatus having two different blades is used for one dicing guide, and the first blade with high processing accuracy is used. Dicing is performed up to the area where the wafer is slightly cut, and then dicing is performed with a second blade mainly for cutting the dicing tape so that the angle is inclined so as not to touch the first dicing surface. For this reason, even if dicing is repeatedly performed, dicing that is not affected by cutting of the adhesive layer mainly of the dicing tape becomes possible, and the occurrence of chipping and cracking can be greatly reduced.

  In the present invention, the inclination angle of the second blade is set to 5 ° or less, preferably about 3 ° with respect to the vertical direction of the wafer. Therefore, when dicing the second blade, the dicing guide width is increased. What is necessary is just to secure small. Further, at this inclination angle, the second blade hardly touches the wafer surface or the cutting surface in the first dicing, so that the occurrence of chipping and cracking can be greatly reduced in this respect as well.

  The reason why the inclination angle of the second blade is set to 5 ° or less is that when the inclination angle of the second blade is larger than 5 °, it is necessary to increase the width of the dicing guide 4 accordingly.

  As described above, in the present invention, the first blade with high processing accuracy is diced to the area where the wafer is slightly cut, and then the first blade is used mainly for cutting the dicing tape. Dicing is performed at an angle that does not touch the surface. For this reason, according to the method of the present invention, even if dicing is repeatedly performed, the dicing tape can be diced mainly without being affected by the adhesive layer cutting, and the occurrence of chipping and cracking can be greatly reduced.

  In the present invention, the inclination angle of the second blade is optimally set to 5 ° or less, preferably about 3 ° with respect to the vertical direction of the wafer. Therefore, when dicing the second blade, the dicing guide is set. What is necessary is just to ensure the width small. At this inclination angle, the second blade hardly touches the wafer surface or the cutting surface in the first dicing. Therefore, according to the dicing method of the present invention, the occurrence of chipping and cracking can be greatly reduced in this respect as well.

  Hereinafter, embodiments of the present invention will be described.

  To achieve the above object, dicing is performed on one dicing guide of the light emitting diode array using a dicing apparatus having two different blades or two dicing apparatuses having different blades.

  For dicing, first use a blade (first blade) with a fine diamond particle diameter at the tip of the blade, which is effective for cracks and chipping, and set the depth so that the uncut amount of the wafer is about 10-50 μm. After dicing, the uncut area and the upper part of the dicing sheet are cut with another blade (second blade) to complete one dicing.

  The second dicing blade (second blade) is inclined with respect to the vertical direction of the wafer. The angle is such that dicing is started from a position removed from the first dicing position and the blade contacts the wafer from the vicinity of the first uncut portion, and the uncut portion of the wafer and the surface of the dicing tape located therebelow Adjust so that can be cut. Specifically, it is inclined at 5 ° or less, preferably about 3 ° with respect to the vertical direction of the wafer.

  Since the second dicing is mainly intended for cutting the dicing tape, the blade (second blade) is different from the first dicing blade (first blade) in that the diameter of diamond particles at the tip of the blade A relatively rough blade is suitable, and dicing is performed at high speed.

  The effect on the chipping and cracking in the uncut region due to this is small due to the small amount of cutting, and the active region of the light emitting diode array itself is formed near the wafer surface, so there is no problem at all. .

  In other words, chip processing (dimension) accuracy, chipping and cracking problems are all determined by the first dicing, but the blade used at the first time does not come into contact with the dicing tape at all, so the adhesive material of the conventional dicing tape Stable dicing is possible without causing deterioration over time due to clogging of the blade.

  On the other hand, the second dicing can be used under the condition that the adhesive material of the dicing tape is not easily clogged as described above, and there is almost no influence on the element even if deterioration with time occurs. Further, since the inclination angle is set to 5 ° or less, preferably about 3 °, it is not necessary to ensure a large dicing guide width, and this angle is set so as not to touch the first dicing surface. There is no effect on cracks and cracks.

<Example>
An embodiment of a dicing method for a light-emitting diode array according to the present invention will be described with reference to FIGS.

  FIG. 1 is an enlarged view of a part of a 350 μm thick semiconductor wafer on which a chip pattern of a double-sided electrode type 600 DPI light emitting diode array is formed, and each light emitting diode array chip 1 adjacent to each other with a dicing guide 4 as a boundary. It is shown. 3 is a line indicating the first dicing position of the chip 1, and 5 is a target pattern for dicing. The uncut amount D1 during dicing is designed to be 3.5 μm. Reference numeral 6 denotes an imaginary line indicating the second dicing position, which is a position 15 μm away from the first dicing position 3 (distance D2).

  When the chip is cut from the wafer by dicing, as shown in FIG. 2, the wafer is first fixed on the dicing table 11 by vacuum suction in a state where the wafer is stuck to the dicing tape 9. First, as shown in FIG. 2A, the depth of the first dicing blade 8A inclined by about 1 ° (θ1) with respect to the vertical direction of the wafer along the line of the first dicing position 3 is obtained. Dicing is performed up to 320 μm (remaining amount of cutting 30 μm).

  Here, the first blade 8A uses a blade with a fine diamond particle diameter at the tip of the blade that is effective for cracks and chipping. The dicing speed is as low as 1 to 2 mm / second, and cracks and chips during dicing are prevented. The conditions were set as low as possible.

  Next, as shown in FIG. 2 (b), the second blade 8B tilted by about 3 ° (θ2) with respect to the vertical direction of the wafer along the imaginary line at the second dicing position 6 A 30 μm uncut region and a part of the surface of the dicing tape 9 (up to a depth of 20 μm) are cut. Here, unlike the first blade 8A, a blade having a relatively coarse diamond particle diameter is used as the second blade 8B, and the dicing speed is 5 to 10 mm / sec. The conditions were such that clogging with the material was less likely to occur.

  As the dicing tape 9, a tape having a total thickness of 90 μm and a thickness of the adhesive layer 10 on the surface of 10 μm was used.

  Next, the dicing table 11 is rotated 180 ° in the horizontal plane, and the chips adjacent to the dicing guide 4 in the width direction are diced in the same manner as in FIGS. 2A and 2B, and the inverted trapezoid as shown in FIG. The chip cross-sectional shape was finished.

  Regarding the X-axis dicing, after completion of the Y-axis dicing, dicing was performed using another standard dicing apparatus.

  In the above embodiment, the inclination angle θ2 of the uncut region and the second blade 8B for cutting the dicing tape is set to about 3 °. However, when the inclination angle is increased, it is necessary to increase the width of the dicing guide 4 accordingly. Therefore, the inclination angle θ2 is desirably 5 ° or less. The minimum value of the inclination angle θ2 is determined by the thickness of the wafer, the uncut amount, the uncut width (D), and the shape of the first dicing surface.

It is a top view of the wafer which shows the dicing method of the light emitting diode array of this invention. It is a side view at the time of chip | tip cutting | disconnection which shows the dicing method of the light emitting diode array of this invention. It is a side view after the chip | tip cutting | disconnection which shows the dicing method of the light emitting diode array of this invention. It is a top view of the wafer which shows a light emitting diode array. It is a side view at the time of the chip | tip cutting | disconnection of the conventional light emitting diode array. It is the top view after the chip | tip cutting | disconnection of the conventional light emitting diode array.

Explanation of symbols

1 chip 2 light emitting dot (light emitting diode)
3 Dicing position for the first time 4 Dicing guide for the Y axis 6 Dicing position for the second time 7 Dicing guide for the X axis 8A First blade 8B Second blade 9 Dicing tape 10 Adhesive layer 11 Dicing table

Claims (6)

In a method of dicing a light emitting diode from a wafer in which a number of light emitting diodes are formed and a dicing tape is pasted on the back surface,
Dicing to the area where the wafer is slightly cut with the first blade with high processing accuracy,
After that, with the second blade mainly for cutting dicing tape, tilt it at an angle of 5 ° or less with respect to the vertical direction of the wafer so that it does not touch the first dicing surface, and dicing the remaining area and dicing. A dicing method comprising cutting an upper portion of a tape. In a method for dicing a light emitting diode array along a dicing guide formed between the respective arrays, from a wafer having a light emitting diode array formed and having a dicing tape attached to the back surface thereof,
Dicing to the area where the wafer is slightly cut with the first blade with high processing accuracy,
After that, with the second blade mainly for cutting dicing tape, tilt it at an angle of 5 ° or less with respect to the vertical direction of the wafer so that it does not touch the first dicing surface, and dicing the remaining area and dicing. A dicing method comprising cutting an upper portion of a tape. The dicing method according to claim 1 or 2,
A dicing method comprising cutting a wafer by about 10 to 50 μm with the first blade having high processing accuracy. In the dicing method according to any one of claims 1 to 3,
For the first blade, a blade with a relatively small diamond particle diameter at the tip of the blade is used, and low-speed dicing of 1 to 2 mm / second is performed.
The dicing method is characterized in that the second blade uses a blade having a relatively coarse diamond particle diameter at the tip of the blade and performs high-speed dicing at 5 to 10 mm / sec. In the dicing method according to any one of claims 2 to 4,
A dicing method characterized by performing dicing twice at two locations in the width direction of one dicing guide and cutting into an inverted trapezoidal shape. The dicing method according to claim 5, wherein
A dicing method, wherein the first blade is tilted by about 1 ° with respect to the vertical direction of the wafer.

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