JP2010080766A - Dicing method, wire saw, and dicing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To accurately cut off a rectangular (oblong) chip from a wafer by a compact device structure. <P>SOLUTION: A wire saw includes first and second wire groups 3A, 3B of different wire pitches as wire groups extended between guide rollers 10A, 10B. A control device 30 controls to drive a head 20 or the like to sequentially execute a process of disposing the wafer W held by a work holder part 24 in opposition to the wire group 3A to radially feed it, a process of detaching the wafer W from the wire group 3A, rotating the wafer W by 90° and disposing the wafer W at a position opposed to the wire group 3B, a process of radially feeding the wafer W relative to the wire group 3B and a process of detaching the wafer W from the wire group 3B to bring it out. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a dicing method, a wire saw, and a dicing apparatus for cutting a chip by cutting a wafer into a lattice shape.

  As a wafer dicing method (apparatus) for cutting a chip from a semiconductor wafer (hereinafter abbreviated as a wafer) on which an integrated circuit is formed, conventionally, a wafer is fixed on a dicing table and a circular blade (dicing blade) made of a grinding wheel is used. A method of moving along a scribe line on a wafer has been common.

  However, in this method, since it is difficult to reduce the thickness of the circular blade, many portions of the wafer are wasted as a cutting allowance (scribe line width), and the circular blade is frequently worn out due to excessive wear of the circular blade. There is a problem that needs to be exchanged.

Therefore, in recent years, a wafer dicing method (apparatus) using a wire saw instead of the wafer dicing direction using a circular blade has been considered (for example, Patent Document 1). According to this, the cutting allowance (scribe line width) can be narrowed, and the replacement frequency due to wear can be reduced by using a long wire.
JP 11-40521 A

  By the way, when cutting a rectangular (rectangular) chip using a wire saw, there are the following problems. That is, the wire pitch in a wire saw is usually constant, so when cutting a rectangular chip using a wire saw, two wire saws corresponding to the short side and the long side of the chip are used, for example, First, after cutting the wafer along the short side of the chip with the wire saw on one side, it is necessary to transfer the wafer to the wire saw on the other side and cut the wafer along the long side of the chip. Therefore, an apparatus for cutting out rectangular chips is likely to be increased in size, and it may be accompanied by a positioning error at the time of wafer transfer, so that it is difficult to ensure cutting accuracy. Therefore, it is desirable to solve this point.

  In addition, although the point which cuts out a rectangular (rectangular) chip | tip using a wire saw is also described in the said patent document 1, in patent document 1, it runs a wire along the scribe line printed on the wafer surface at the grid | lattice form. However, there is only a description that the chip is cut out, and the above-mentioned problems cannot be solved at all.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to enable a rectangular (rectangular) chip to be cut out from a wafer with high accuracy and in a compact apparatus configuration.

  In order to solve the above problems, the present invention uses a wire saw having a wire group consisting of cutting wires that are stretched in parallel with each other between a pair of guide rollers and driven in the axial direction. A method of cutting a rectangular chip having a first side and a second side having a different length from a wafer, for cutting at a pitch corresponding to a dimension of the first side of the rectangular chip as the wire group. Preparing a wire saw in which a first wire group in which wires are arranged and a second wire group in which cutting wires are arranged at a pitch corresponding to the dimension of the second side are arranged in the axial direction of the guide roller; The wafer is arranged so that its surface faces the first wire group, and the wafer is rectangularly cut and fed relative to the first wire group in a direction parallel to the thickness direction. A first cutting step of cutting along the second side of the chip, and after the first cutting step, the wafer is moved away from the first wire group by moving the wafer in a direction opposite to the cutting feed direction; A wafer transfer step of rotating the wafer by 90 ° about an axis orthogonal to the surface and arranging the wafer so that the surface faces the second wire group, and after the wafer transfer step, the second wire group A second cutting step of cutting the wafer along the first side of the rectangular chip by relatively cutting and feeding the wafer in a direction parallel to the thickness direction thereof, and after the second cutting step And a wafer unloading step of unloading and unloading the wafer from the second wire group by moving the wafer in a direction opposite to the cutting feed direction.

  In this way, according to the method of dicing a wafer using a wire saw having first and second wire groups having different wire pitches between a pair of guide rollers, a rectangular (rectangular) chip can be formed with only a single wire saw. It can be easily cut out. Therefore, a rectangular chip can be cut out with less equipment compared to the conventional method that requires two wire saws. Further, since transfer of the wafer between the apparatuses (wire saws) becomes unnecessary, the inconvenience that the transfer accuracy is lost due to the transfer can be avoided.

  In the description of the claims, “the pitch corresponding to the dimension of the first side (or the second side) of the rectangular chip” means that the wafer is cut along the dimension of the first side (or the second side). The dimension which can be made, specifically, the dimension obtained by adding the cutting allowance by the cutting wire to the dimension of the first side (or the second side).

  On the other hand, the wire saw according to the present invention is a wire saw used for cutting out a rectangular chip having a first side and a second side having a different length from the wafer, and is parallel to each other between a pair of guide rollers. A wire group composed of cutting wires that are stretched in a line and driven in the axial direction, and the wire group has the first pitch corresponding to the dimension of the first side of the rectangular chip. The first wire group in which the cutting wires are arranged and the second wire group in which the cutting wires are arranged at a second pitch corresponding to the dimension of the second side are between the pair of guide rollers. Are arranged in the axial direction.

  A dicing apparatus according to the present invention is a dicing apparatus for cutting out a rectangular chip having a first side and a second side having a different length from the wafer, the wire saw and the wafer being A moving means for moving the wafer relative to the wire group of the wire saw, and a control means for driving and controlling the moving means; And the control means arranges the wafer so that a surface thereof faces the first wire group, and cuts and feeds the wafer relative to the first wire group in a direction parallel to the thickness direction. By doing so, the wafer is moved from the first wire group by moving the wafer in a direction opposite to the direction of cutting and feeding the wafer along the second side of the rectangular chip. And moving the wafer 90 ° about an axis orthogonal to the surface and placing the wafer so that the surface faces the second wire group, and the thickness of the wafer with respect to the second wire group. An operation of cutting the wafer along the first side of the rectangular chip by relatively cutting and feeding in a direction parallel to the direction, and a second by moving the wafer in a direction opposite to the direction of the cutting and feeding. The driving of the moving means is controlled so as to sequentially execute the operation of pulling the wafer away from the wire group and carrying it out.

  According to such a dicing apparatus, it becomes possible to automatically cut out rectangular chips based on the dicing method.

  As a specific configuration of the wire saw, each wire group of the wire saw is composed of the cutting wires stretched in the horizontal direction, and the holding means holds the wafer above the wire group. The moving means is configured to rotate the holding means about a vertical axis, a lifting mechanism for moving the holding means up and down, and the holding means to the guide. And a horizontal movement mechanism that horizontally moves in the axial direction of the roller.

  According to such a configuration, since the holding means side is moved with respect to the wire group, the wafer can be relatively moved with respect to the wire group with a relatively small driving force. Further, since the moving means is constituted by the rotation mechanism and the linear movement mechanism (elevating mechanism, horizontal moving mechanism), the wafer can be moved with respect to the wire group with a simple configuration.

  According to the present invention, a rectangular (rectangular) chip can be easily cut out from a wafer with only a single wire saw. Therefore, compared to the conventional method (apparatus) that requires two wire saws, it is possible to cut out a rectangular chip with a compact facility, and it is more accurate because it can avoid the occurrence of positioning errors due to wafer transfer. A rectangular chip can be cut out well.

  A preferred embodiment of the present invention will be described with reference to the drawings.

  1 to 3 show a dicing apparatus according to the present invention. FIG. 1 is a front view, FIG. 2 is a plan view, and FIG. 3 is a side view schematically showing a wire saw.

  The dicing apparatus shown in these figures cuts out a rectangular (rectangular) chip by dicing a semiconductor wafer (hereinafter abbreviated as a wafer) on which an integrated circuit is formed. The basic structure is as follows: It is common. That is, it has a configuration including one wire saw.

  As shown in the figure, the dicing apparatus has a base 1. On the base 1, a pair of support plates 12, 12 that are opposed to each other in the front-rear direction (vertical direction with respect to the paper surface of FIG. 1) are erected at a predetermined interval. Between these support plates 12 and 12, a pair of guide rollers that are rotatably supported by the support plates 12 and 12 and extend in parallel in the front-rear direction are arranged in two upper and lower stages.

  A plurality of grooves arranged in the roller axial direction (front-rear direction) are formed on the outer peripheral surfaces of the respective guide rollers 10A to 10D, and a cutting wire 2 (hereinafter abbreviated as "wire 2") is fitted into these grooves. ) Is wound around the guide rollers 10A to 10D. As a result, a wire group in which the wires 2 are arranged in the front-rear direction is formed between the guide rollers.

  The pitch between the grooves in each of the guide rollers 10 </ b> A to 10 </ b> D is set wider on the rear side than on the front side with the middle portion in the roller axial direction as a boundary. As a result, the first wire group 3A and the second wire group 3B, which are arranged in the axial direction of the guide rollers 10A to 10D and have different wire pitches, are provided as the wire group. Here, the wire pitch of each of the wire groups 3A and 3B corresponds to one side of a chip to be cut out from the semiconductor wafer W (hereinafter simply referred to as the wafer W). That is, the chip cut out from the wafer W is a rectangular (rectangular) chip as described above, and the wire pitch (first pitch) of the first wire group 3A is a dimension corresponding to the short side (first side) dimension of the chip. In other words, the dimension is such that the wafer W can be cut by the short side dimension of the chip, more specifically, the dimension obtained by adding the cutting margin by the cutting wire 2 to the short side dimension of the chip, and the wire pitch of the second wire group 3B ( (Second pitch) is a dimension corresponding to the long side (second side) dimension of the chip, that is, a dimension capable of cutting the wafer W by the long side dimension of the chip, more specifically, the long side dimension of the chip is determined by the cutting wire 2. It is set to the dimension with cutting allowance added.

  Both ends of the wire 2 are respectively wound around unwinding / winding bobbins provided on the base 1. These bobbins are driven to rotate by a drive motor (not shown) and the guide rollers 10A to 10D are driven to rotate by the drive motors 11A to 11D, respectively. The wire 2 is configured to be switched between a state where the wire 2 is being wound and the state where the wire 2 is wound around the other bobbin and vice versa. That is, the wire groups 3A and 3B formed between the guide rollers 10A to 10D are reciprocally driven (reciprocating) in the forward direction and the reverse direction.

  The upper guide rollers 10A and 10B (corresponding to the pair of guide rollers of the present invention) among the four guide rollers 10A to 10D are used as a work area, and a wafer W is held above the work area. A head 20 for cutting and feeding the wire groups 3A and 3B is movably disposed.

  The head 20 includes a work holding unit 24 for holding the wafer W and a rotation motor 22 for rotating the work holding unit 24. The work holding unit 24 is a so-called vacuum chuck that holds the wafer W by suction on its surface, is supported so as to be rotatable about a vertical axis with respect to the head 20 with the suction surface facing downward, and is driven by the motor 22. It has come to be.

  The head 20 is provided so as to be movable in the vertical direction (up and down) and in the front-rear direction by a drive mechanism including a so-called screw feed mechanism. In the front-rear direction, the guide rollers 10A to 10D are arranged as shown in FIG. From a predetermined standby position PS located outside (front side) to a predetermined work position, specifically, a first work position P1 above the first wire group 3A and a second work position P2 above the second wire group 3B. It is possible to move over the range.

  The drive mechanism of the head 20 is configured as follows in this embodiment. That is, the column 14 is erected on the base 1 and on the side portions (right side in FIG. 1) of the guide rollers 10A to 10D. The column 14 is provided with a fixed rail 16 extending in the vertical direction and a screw shaft parallel to the rail 16. A movable table 18 is mounted on the fixed rail 16 and the movable table 18 is not shown. The screw shaft is screwed into the nut portion, and an elevating motor 15 fixed to the column 14 is connected to the screw shaft. The movable table 18 is provided with a fixed rail 19 extending in the front-rear direction and a screw shaft parallel to the rail 19, and a head 20 is mounted on the fixed rail 19 and the head 20 is not shown. The screw shaft is screwed into the nut portion, and a forward / backward feed motor 17 fixed to the movable table 18 is connected to the screw shaft.

  That is, the head 20 moves in the front-rear direction with respect to the movable table 18 by driving the front-rear feed motor 17, while the movable table 18 moves up and down with respect to the column 14 by driving the lifting motor 15. Is configured to move up and down and move back and forth. In this embodiment, the work holding portion 24 corresponds to the holding means according to the present invention, and the movable table 18, the fixed rails 16, 19 and the motors 15, 17, 22 and the like are the moving means according to the present invention. Equivalent to.

  The wire saw is provided with a control device 30 composed of an NC device or the like, and the motors 11A to 11D, 15, 17 and 22 are all electrically connected to the control device 30. When the wafer W is diced, the motors 11A to 11D, 15, 17, 22 and the like are controlled by the control device 30 so that the wafer W is diced as follows. The Hereinafter, the dicing operation of the wafer W based on the control of the control device 30 will be described.

  First, as a preparation process, the wafer W is set on the head 20. Specifically, as shown by the one-dot chain line in FIG. 3, the head 20 is disposed at the standby position PS, and the wafer W is sucked and held by the work holding unit 24 so that the circuit forming surface faces downward. At this time, the wafer W is held at a predetermined position of the work holding unit 24 in a predetermined direction with reference to the orientation flat.

  In this preparatory work, for example, a wafer transfer table is provided at the standby position PS, and the wafer W is placed on the table, and the wafer W is held by the work holding unit 24 as the head 20 moves up and down. You may make it automate by doing.

  After this work, when a start switch (not shown) is operated, a dicing operation is started.

  In this dicing operation, first, the wire groups 3A and 3B are driven in the axial direction by driving the guide rollers 10A to 10D. Further, after the head 20 has moved to a predetermined height position for wafer transfer, the head 20 moves rearward from the standby position PS, whereby the wafer W is disposed at the first work position P1 above the first wire group 3A. The At this time, by driving the work holding unit 24, the wafer W is in a predetermined direction with respect to the first wire group 3A, that is, a dicing (scribe) line along the long side of the chip is connected to the wire 2 of the first wire group 3A. The orientation of the wafer W is set so as to be parallel.

  When the head 20 is lowered, the wafer W is cut and fed in the direction parallel to the thickness direction with respect to the first wire group 3A, whereby the wafer W is moved by the wire 2 of the first wire group 3A. (Refer to FIG. 4A; first cutting step).

  When the wafer W is cut and fed by a set amount, the head 20 turns upward, and the wafer W is pulled upward from the first wire group 3A and placed at a predetermined height position for wafer transfer. Then, the head 20 moves rearward from the first work position P1, whereby the wafer W is placed at the second work position P2 above the second wire group 3B (wafer transfer process). During the movement, the wafer W is rotated by 90 ° by driving the work holding unit 24, so that the dicing line along the short side of the chip is parallel to the wire 2 of the second wire group 3B. Set.

  Thereafter, the head 20 is lowered to cut and feed the wafer W to the second wire group 3B, and the wafer W is cut along the dicing line by the wire 2 of the second wire group 3B. As a result, the wafer W is cut into a lattice and a plurality of rectangular chips are cut out (see FIG. 4B; second cutting step).

  When the wafer W is cut and fed by a set amount, the head 20 turns upward, and the wafer W is pulled upward from the second wire group 3B and placed at a predetermined height position for wafer transfer. Then, the head 20 moves forward from the second work position P2, whereby the wafer W is unloaded from the second work position P2 to the standby position PS (wafer unloading process).

  Thereafter, the wafer W is removed from the work holding unit 24, whereby a series of dicing operations is completed.

  According to the dicing apparatus (wafer dicing method) described above, rectangular chips can be cut out from the wafer W by a dicing apparatus including only one wire saw. Therefore, as compared with the case where two wire saws are used as in the prior art, the entire apparatus can be made compact because the work holding portion and its drive mechanism can be shared. Particularly, since the workpiece holding unit 24 is moved by a simple mechanism such as the so-called rotation mechanism and linear motion mechanism (elevating mechanism, horizontal movement mechanism) as described above, the entire apparatus can be made compact in this respect as well.

  In addition, since there is no need to transfer the wafer between apparatuses (wire saws) as in the case of using two wire saws, it is possible to avoid the occurrence of positioning errors and the like due to the transfer. A rectangular chip can be cut out well.

  Further, according to the above dicing apparatus, the wire groups 3A and 3B are provided on the common guide rollers 10A and 10B so as to be lined up and down, and the wafer W is moved in the front and rear direction after the dicing work by the first wire group 3A. Since the wafer W can be quickly placed at the second work position P2 above the second wire group 3B by (sliding), the dicing work by the second wire group 3B is performed after the dicing work by the first wire group 3A. Can be quickly transferred to. Therefore, the rectangular chip dicing operation can be performed efficiently.

  In the above-described wire saw (wafer dicing method), the first and second wire groups 3A and 3B are arranged as the wire group in the axial direction of the guide rollers 10A to 10D. The wire groups described above are provided side by side in the axial direction, and correspond to the type of wafer W based on the control of the head 20 and the like by the control device 30 (that is, corresponding to the dimensions of each side of the rectangular chip to be cut) 2 The wafer W may be diced by selectively using one wire group. According to such a configuration, it is possible to cut out a plurality of types of rectangular chips having different dimensions from the wafer W with a dicing apparatus including only one wire saw, which is advantageous in improving versatility.

  In the wire saw, the wire groups 3A and 3B are formed by winding the wire 2 around the four guide rollers 10A to 10D. However, the number of guide rollers may be three or two. . In the case of three guide rollers, two adjacent guide rollers correspond to “a pair of guide rollers” of the present invention.

  Further, the wire saw is formed on the wire groups 3A and 3B that are horizontally stretched between the guide rollers 10A and 10B, with the upper guide roller 10A and 10B among the four guide rollers 10A to 10D as a work area. The wafer W is configured to cut and feed the wafer W, but of course, between the pair of upper and lower guide rollers 10A and 10C (or 10B and 10D) as a work area, the guide rollers 10A and 10C (or 10B and 10D). The wafer W may be cut and fed to the wire groups 3A and 3B that are vertically stretched between the two.

1 is a front view showing a schematic configuration of a dicing apparatus according to the present invention (a dicing apparatus in which a dicing method according to the present invention is implemented). It is a top view which shows schematic structure of a dicing apparatus. It is a side view which shows schematic structure of a dicing apparatus. It is a schematic diagram which shows the state of dicing of a semiconductor wafer, (a) is the state which has cut | disconnected the semiconductor wafer with the 1st wire group, (b) is the state which has cut | disconnected the semiconductor wafer with the 2nd wire group, respectively. Show.

Explanation of symbols

2 cutting wire 3A first wire group 3B second wire group 10A to 10D guide roller 20 head 24 work holding unit 30 controller W semiconductor wafer

Claims (4)

Using a wire saw having a wire group consisting of cutting wires that are stretched in parallel with each other between a pair of guide rollers and driven in the axial direction, a first side and a second having a different length from the first side are used. A rectangular chip having the sides of the wafer,
The wire group includes a first wire group in which cutting wires are arranged at a pitch corresponding to the first side dimension of the rectangular chip, and a cutting wire is arranged at a pitch corresponding to the second side dimension. Preparing a wire saw in which the second wire group is aligned in the axial direction of the guide roller;
The wafer is arranged so that its surface faces the first wire group, and the wafer is cut into a rectangular chip by cutting and feeding the wafer relative to the first wire group in a direction parallel to the thickness direction. A first cutting step of cutting along the second side of
After the first cutting step, the wafer is moved in a direction opposite to the cutting feed direction to separate the wafer from the first wire group, and the wafer is rotated by 90 ° about an axis orthogonal to the surface and the wafer is moved. A wafer transfer step in which the surface is arranged to face the second wire group;
After the wafer transfer step, the wafer is cut along the first side of the rectangular chip by cutting and feeding the wafer relative to the second wire group in a direction parallel to the thickness direction. Two cutting steps;
A dicing method comprising: a wafer unloading step of unloading the wafer from the second wire group by moving the wafer in a direction opposite to the cutting feed direction after the second cutting step. . A wire saw used for cutting out a rectangular chip having a first side and a second side having a different length from the wafer,
A wire group consisting of cutting wires that are stretched in parallel with each other between a pair of guide rollers and driven in the axial direction;
The wire group includes a first wire group in which the cutting wires are arranged at a first pitch corresponding to the first side dimension of the rectangular chip, and a second wire group corresponding to the second side dimension. A wire saw, wherein a second wire group in which the cutting wires are arranged at a pitch is provided so as to be aligned in the axial direction between the pair of guide rollers. A dicing apparatus for cutting out a rectangular chip having a first side and a second side having a different length from the first side,
3. A wire saw according to claim 2, comprising a holding means for adsorbing and holding the wafer from the opposite side of the circuit forming surface, and a moving means for moving the wafer relative to a wire group of the wire saw. Control means for driving and controlling the moving means,
The control means arranges the wafer so that the surface thereof faces the first wire group, and cuts and feeds the wafer relative to the first wire group in a direction parallel to the thickness direction. Cutting the wafer along the second side of the rectangular chip;
The wafer is moved away from the first wire group by moving the wafer in a direction opposite to the cutting feed direction, the wafer is rotated by 90 ° about an axis orthogonal to the surface, and the surface of the wafer is the second wire group. An operation to arrange the two facing each other,
Cutting the wafer along the first side of the rectangular chip by cutting and feeding the wafer relative to the second wire group in a direction parallel to the thickness direction;
The dicing is characterized in that the movement of the moving means is controlled so as to sequentially execute the operation of moving the wafer in the direction opposite to the cutting feed direction and pulling the wafer away from the second wire group. apparatus. The dicing apparatus according to claim 3, wherein
Each wire group of the wire saw is composed of the cutting wires stretched in the horizontal direction, and the holding means is arranged so that the surface of the wafer is parallel to the wire arrangement direction above the wire group. The moving means is a rotating mechanism that rotates the holding means about a vertical axis, a lifting mechanism that moves the holding means up and down, and a horizontal moving mechanism that horizontally moves the holding means in the axial direction of the guide roller. And a dicing apparatus comprising:

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