JP2009141231A - Frame clamping apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a clamping apparatus capable of preventing generation of cracks or chips in dicing of a wafer. <P>SOLUTION: The frame clamping apparatus disposed on the outer periphery of a chuck table 18 for holding a wafer attached to an annular frame is provided with: a support frame installed on the chuck table 18 movably in a diameter direction and immovably in a vertical direction; a movable frame attached to the support frame movably in a vertical direction; a suction means capable of sucking the annular frame disposed on the upper part of the movable frame; and a driving means for driving the movable frame vertically to the support frame. When the driving means vertically moves the movable frame, the annular frame is moved between a position dropped lower than the upper surface of the chuck table 18 and a rise position which is an approximately the same height as the upper surface of the chuck table 18. On the dropped position, a high throughput is obtained, and on the rise position, quality having no crack or chip is obtained. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a frame clamp device that clamps an annular frame on which a wafer sucked and held by a chuck table is mounted via an adhesive tape.

  A semiconductor wafer in which a number of devices such as IC and LSI are formed on the surface, and each device is partitioned by a line to be divided (street), the back surface is ground by a grinding machine and processed to a predetermined thickness. A division line is cut by a dicing machine (cutting machine) and divided into individual devices, which are used for electric devices such as mobile phones and personal computers.

  The dicing apparatus includes a chuck table for holding a semiconductor wafer, a cutting means for cutting the wafer held on the chuck table, and a processing feed means for processing and feeding the chuck table relative to the cutting means. Yes.

  The semiconductor wafer is fixed to approximately the center of an annular frame several cm larger than the wafer diameter by a dicing tape, vacuum-adsorbed to the chuck table, and moved by moving the chuck table to the cutting blade that rotates at high speed by the processing feed means. Is divided into individual devices.

  The chuck table of the dicing apparatus has a frame clamp device (clamp) on the outer periphery, and the wafer is fixed to the chuck table by the frame clamp device fixing the annular frame (for example, JP-A-8-69985). reference).

In order to avoid the cutting blade from coming into contact with the clamp even if the clamp comes into contact with the annular frame during conveyance of the annular frame, or there is a mechanical malfunction or inadvertent operation mistake, for example, Japanese Utility Model Publication No. 5-7414. As shown in FIG. 3, the clamp fixes the annular frame so as to be pulled down below the upper surface of the chuck table.
JP-A-8-69985 Japanese Utility Model Publication No. 5-7414 Japanese Patent Laid-Open No. 11-219962

  By the way, along with the trend of thinning and thinning of electric products, the chip size (device size) of semiconductors tends to gradually become smaller and thinner, and the thickness of wafers to be diced has become thinner than 100 μm. When dicing a wafer, cracks and cracks are likely to occur on the side surfaces and corners of the semiconductor chip due to a decrease in rigidity due to the thinness of the wafer.

  Further, as disclosed in Patent Document 3, the application of attaching a die bonding tape to the back surface of a wafer has been widened, and since the tape for fixing the wafer has become thicker and softer, the tendency to further generate chips and cracks has increased. In order to cope with this problem, various countermeasures have been tried, such as changing the cutting blade used in dicing, changing the processing speed, or changing the dicing tape.

  However, even when these measures were taken, there was a tendency that side cracks and corners of the semiconductor chip were likely to occur, particularly in the peripheral portion of the wafer. On the other hand, when the present inventor repeated experiments, when fixing the frame with the clamp, the frame is pulled down to be positioned below the upper surface of the chuck table. It was found that there was a change in the occurrence of chipping.

  The present invention has been made in view of these points, and it is an object of the present invention to provide a frame clamp device that can arbitrarily select whether or not the frame clamp device pulls down the frame when the wafer is cut.

  According to the present invention, there is provided a frame clamp device disposed on the outer periphery of a chuck table that sucks and holds a wafer mounted on an annular frame via an adhesive tape, and is movable in a radial direction with respect to the chuck table. A support frame mounted immovably in a direction, a movable frame mounted so as to be movable up and down with respect to the support frame, and the wafer disposed on the movable frame and sucked and held by the chuck table. A suction means for sucking the annular frame; and a drive means for moving the movable frame up and down relative to the support frame. The drive means pulls down the annular frame from the upper surface of the chuck table. Position, and the rising position where the upper surface of the chuck table and the lower surface of the annular frame are substantially the same height Frame clamping device is provided, wherein the between a movable movable frame.

  Preferably, the attracting means is composed of a permanent magnet. Alternatively, the suction means is composed of a vacuum pad.

  According to the frame clamp device of the present invention, it is possible to arbitrarily select whether or not the frame is pulled down with respect to the upper surface of the chuck table, and it is possible to suppress the occurrence of chip side cracks and corner chipping that have occurred by pulling down the frame. .

  In addition, the use of permanent magnets and vacuum pads as the suction means eliminates the need for conventional clamp claws and allows the thickness to be omitted. Sometimes the vertical movement of the cutting blade to avoid the frame can be kept small.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 shows an external view of a cutting device (dicing device) 2 having a conventional clamp 19 and capable of dicing a wafer into individual chips (devices).

  On the front side of the cutting device 2, there is provided operating means 4 for an operator to input instructions to the device such as machining conditions. In the upper part of the apparatus, there is provided a display means 6 such as a CRT for displaying a guidance screen for an operator and an image taken by an imaging means described later.

  As shown in FIG. 2, on the surface of the wafer W to be diced, the first street S1 and the second street S2 are formed orthogonally, and the first street S1 and the second street S2 A plurality of devices D are partitioned and formed on the wafer W.

  The wafer W is attached to a dicing tape T that is an adhesive tape, and the outer peripheral edge of the dicing tape T is attached to an annular frame F. As a result, the wafer W is supported by the frame F via the dicing tape T, and a plurality of wafers (for example, 25 sheets) are accommodated in the wafer cassette 8 shown in FIG. The wafer cassette 8 is placed on a cassette elevator 9 that can move up and down.

  Behind the wafer cassette 8, a loading / unloading means 10 for unloading the wafer W before cutting from the wafer cassette 8 and loading the wafer after cutting into the wafer cassette 8 is disposed. Between the wafer cassette 8 and the loading / unloading means 10, a temporary placement area 12, which is an area on which a wafer to be carried in / out, is temporarily placed, is provided. Positioning means 14 for positioning at a certain position is provided.

  In the vicinity of the temporary placement area 12, transport means 16 having a turning arm that sucks and transports the frame F integrated with the wafer W is disposed, and the wafer W carried to the temporary placement area 12 is Adsorbed by the conveying means 16 and conveyed onto the chuck table 18 and sucked by the chuck table 18, and held on the chuck table 18 by fixing the frame F by a plurality of fixing means (clamps) 19. .

  The chuck table 18 is configured to be rotatable and reciprocally movable in the X-axis direction. Above the movement path of the chuck table 18 in the X-axis direction, an alignment unit 20 that detects a street to be cut of the wafer W is provided. It is arranged.

  The alignment unit 20 includes an imaging unit 22 that images the surface of the wafer W, and can detect a street to be cut by a process such as pattern matching based on an image acquired by imaging. The image acquired by the imaging unit 22 is displayed on the display unit 6.

  On the left side of the alignment means 20, a cutting means 24 for cutting the wafer W held on the chuck table 18 is disposed. The cutting means 24 is configured integrally with the alignment means 20, and both move together in the Y-axis direction and the Z-axis direction.

  The cutting means 24 is configured by attaching a cutting blade 28 to the tip of a rotatable spindle 26 and is movable in the Y-axis direction and the Z-axis direction. The cutting blade 28 is located on the extended line of the imaging means 22 in the X-axis direction.

  Referring to FIG. 3, a plan view of a frame clamp device 30 according to an embodiment of the present invention is shown. FIG. 4 is a front view of the frame clamp device and shows the clamp unit 36. The frame clamp device 30 includes a fixing member 32 that is fixed to a base 31 (see FIG. 5) 31 of the chuck table 18 with screws 34.

  The distal ends of a pair of guide shafts 38 and 40 are screwed to the fixing member 32, and the guide shafts 38 and 40 extend in parallel to the suction surface of the chuck table 18. The guide shafts 38 and 40 are respectively inserted into support blocks 42 and 44, and a support frame (support plate) 46 is fixed to the support blocks 42 and 44.

  As shown in FIG. 4, a clamp drive air cylinder 48 is attached to the support frame 46. A plate 52 is fixed to the tip of the piston rod 50 of the clamp drive air cylinder 48.

  One end of clamp drive shafts 54 and 56 is fixed to the plate 52, and a plate 58 is fixed to the other end of the clamp drive shafts 54 and 56. The clamp drive shafts 54 and 56 are inserted into the support blocks 42 and 44 and extend. The plate 52, the pair of clamp drive shafts 54 and 56, and the plate 58 constitute a movable frame 55.

  A magnet driven air cylinder 60 is attached to the lower surface of the plate 58. A plate 64 is fixed to the tip of the piston rod 62 of the magnet drive air cylinder 60, and a pair of magnets (permanent magnets) 66, 68 are embedded and fixed to the plate 64 so as to be half exposed.

  The magnets 66 and 68 are accommodated in a magnet case 70, and the upper surface thereof is closed by a magnet cover 72. The magnet cover 72 is made of a ferromagnetic material such as an iron plate. The clamp unit 36 shown in FIG. 3 shows a state where the magnet cover 70 is removed.

  Hereinafter, the operation of the frame clamp device 30 configured as described above will be described. First, the clamp unit 36 shown in FIG. 3 is moved in the vertical direction in FIG. 3 along the guide shafts 38 and 40 according to the inch diameter of the wafer, and the clamp unit 36 is fixed at an appropriate position by a fixing means (not shown). , 40 is fixed.

  Next, the clamp drive air cylinder 48 is driven to move the clamp unit 36 to the pull-down position shown in FIG. 4 (A) or the horizontal position shown in FIG. 4 (B). Since the support frame 46 is fixed to the support block 42 inserted into the pair of guide shafts 38, 40, the height position with respect to the chuck table 18 is constant.

  Therefore, as shown in FIG. 4A, when compressed air is introduced into the clamp drive air cylinder 48 and the piston rod 50 is extended, the movable frame 55 is moved downward with respect to the support frame 46, and the chuck It is positioned at a withdrawal position with respect to the upper surface of the table 18.

  With the movable frame 55 positioned at the pull-down position in this way, the magnet drive air cylinder 60 is driven to extend the piston rod 62, and the magnets 66 and 68 that have been at the retracted position are raised as indicated by two-dot chain lines. Positioned at suction positions 66 'and 68'. Since the magnet cover 72 is made of a ferromagnetic material, it can be attracted and held at the position where the annular frame F is pulled down by the magnets 66 ′ and 68 ′ at the attracting position.

  A side sectional view around the chuck table 18 in this state is schematically shown in FIG. However, the configuration of the clamp unit 36 ′ shown in FIG. 5A is slightly different from the configuration of the clamp unit 36 shown in FIG. The magnet 78 is supported by a magnet support member 76, and the magnet support member 76 is moved in the vertical direction by the drive unit 74.

  As shown in FIGS. 4A and 5A, normal dicing of the semiconductor wafer W is performed in a state where the annular frame F is pulled down from the upper surface of the chuck table 18 by the clamp unit 36 or 36 ′. The In this state, the annular frame F is pulled down, so that it does not interfere with the cutting blade 28 and high throughput can be maintained.

  When the thickness of the wafer W becomes very thin as 100 μm or less, and the occurrence of chipping or cracks on the side surfaces and corners of each diced semiconductor chip becomes conspicuous, the movable frame 55 of the clamp unit 36 is shown in FIG. Move to the raised position shown in (B).

  That is, the piston rod 50 is contracted by discharging the compressed air from the clamp drive air cylinder 48. Thereby, the movable frame 55 rises with respect to the support frame 46, and the upper surface of the magnet cover 72 can be set to approximately the same height as the upper surface of the chuck table 18.

  The cutting operation in this state is schematically shown in FIG. An arrow X is the feed direction of the chuck table 18. In the state shown in FIG. 5B, since the dicing tape T is kept horizontal without being pulled down, occurrence of chip side cracks and corner chippings caused by pulling down the frame F is suppressed. Processing quality can be improved.

  According to the frame clamping device 30 of the embodiment of the present invention, it is possible to arbitrarily select whether or not the annular frame F is pulled down with respect to the upper surface of the chuck table, and to select the more important one of throughput and processing quality. . When the processing quality is selected, it is possible to suppress the occurrence of chip side cracks and corner chipping that have occurred by pulling down the frame.

  Referring to FIG. 6, another embodiment of the frame clamping device is shown. In the present embodiment, the annular frame F is adsorbed by the vacuum pad 80. The vacuum pad 80 is mounted on the support member 76 ′, and the support member 76 ′ is driven up and down by the drive unit 74.

  As described above, even in the present embodiment using the vacuum pad 80 as the attracting means, it is possible to achieve the same effect as the above-described embodiment using the magnets 66, 68, 78 as the attracting means.

  In the cutting apparatus 2 configured as described above, the wafer W accommodated in the wafer cassette 8 is sandwiched by the frame F by the loading / unloading means 10, and the loading / unloading means 10 moves to the rear of the apparatus (Y-axis direction). When the nipping is released in the placing area 12, the placing area 12 is placed in the temporary placing area 12. Then, the wafer W is positioned at a certain position by the positioning means 14 moving in a direction approaching each other.

  Next, the frame F is adsorbed by the transport unit 16, and the wafer W integrated with the frame F is transported to the chuck table 18 and held by the chuck table 18 as the transport unit 16 rotates. Then, the chuck table 18 moves in the X-axis direction, and the wafer W is positioned directly below the alignment means 20.

  The image used for pattern matching at the time of alignment in which the alignment unit 20 detects a street to be cut needs to be acquired in advance before cutting. Therefore, when the wafer W is positioned directly below the alignment unit 20, the imaging unit 22 captures the surface of the wafer W and causes the display unit 6 to display the captured image.

  Hereinafter, an outline of alignment by the imaging unit 22 will be described. The operator of the cutting device 2 operates the operation means 4 to search for a key pattern that is a target for pattern matching while slowly moving the image picked up by the image pickup means 22 and displayed on the display means 6. This key pattern uses, for example, a characteristic part of a circuit in the device D.

  When the operator determines a key pattern, an image including the key pattern is stored in a memory provided in the alignment unit 20 of the cutting apparatus 2. Further, the distance between the key pattern and the center line of the streets S1 and S2 is obtained by a coordinate value or the like, and the value is also stored in the memory.

  Further, by slowly moving the captured image on the screen, an interval between the adjacent streets (street pitch) is obtained by a coordinate value or the like, and the street pitch value is also stored in the memory of the alignment means 20. .

  At the time of cutting along the street of the wafer W, the alignment unit 20 performs pattern matching between the stored key pattern image and the image actually acquired by the imaging unit 22. This pattern matching is performed at at least two points separated from each other along the same street S1 extending in the X-axis direction.

  First, while slowly moving the image picked up at point A on the screen, pattern matching between the stored key pattern and the actual image key pattern is performed, and the screen is fixed in a state where the key pattern is matched.

  When pattern matching is performed from the imaging screen at point A as described above, the chuck table 18 is moved in the X-axis direction, and pattern matching is performed at point B that is considerably separated from point A in the X-axis direction.

  At this time, instead of moving from point A to point B at once, pattern matching is performed, but pattern matching is performed as necessary at a plurality of points in the middle of movement to point B to correct the deviation in the Y-axis direction. It is preferable to slightly rotate the chuck table 18 to perform θ correction and finally perform pattern matching at point B.

  When the pattern matching at the points A and B is completed, the straight line connecting the two key patterns is parallel to the street S1, and the cutting means 24 is moved by the distance between the key pattern and the center line of the street S1. By moving in the Y-axis direction, the street to be cut and the cutting blade 28 are aligned.

  When the street to be cut and the cutting blade 28 are aligned, the chuck table 18 is moved in the X-axis direction, and the cutting means 24 is lowered while rotating the cutting blade 28 at a high speed. The street was cut.

  When the street is cut by the cutting blade 28, the street is cut while jetting cutting water from a cutting water supply nozzle (not shown) toward the cutting blade 28 and the wafer W. The cutting blade 28 is cooled by ejecting cutting water onto the cutting blade 28.

  By performing cutting while feeding the cutting means 24 in the Y-axis direction by the street pitch stored in the memory, all the streets S1 in the same direction are cut. Furthermore, when the chuck table 18 is rotated by 90 ° and then the same cutting as described above is performed, the streets S2 are all cut and divided into individual devices D.

  The wafer W that has been cut is moved in the X-axis direction by the chuck table 18 and is then gripped by the transfer means 25 that can move in the Y-axis direction and transferred to the cleaning device 27. The cleaning device 27 cleans the wafer by rotating the wafer W at a low speed (for example, 300 rpm) while jetting water from the cleaning nozzle.

  After the cleaning, the wafer W is dried at a high speed (for example, 3000 rpm) by blowing air from the air nozzle and drying the wafer W. Then, the wafer W is adsorbed by the conveying means 16 and returned to the temporary storage area 12, and then the loading / unloading means. 10, the wafer W is returned to the original storage location of the wafer cassette 8.

It is an external appearance perspective view of the cutting device which can apply the frame clamp device of the present invention. It is a perspective view which shows the wafer integrated with the flame | frame. It is a top view of the frame clamp device concerning the embodiment of the present invention. 4A is a front view of the clamp unit in a state where the movable frame is positioned at the pull-down position, and FIG. 4B is a front view of the clamp unit in a state where the movable frame is positioned in the raised position. FIG. 5A is a side sectional view showing how the wafer is cut when the frame clamp device is pulled down, and FIG. 5B is a side sectional view showing how the wafer is cut when the frame clamp device is raised. is there. It is side surface sectional drawing of other embodiment of this invention using a vacuum pad as an adsorption | suction means.

Explanation of symbols

2 Cutting device 18 Chuck table 24 Cutting means 26 Spindle 28 Cutting blade 30 Frame clamp device 36 Clamp units 38 and 40 Guide shafts 42 and 44 Support block 46 Support frame (support plate)
48 Clamp drive air cylinders 54, 56 Clamp drive shaft 55 Movable frame 60 Magnet drive air cylinders 66, 68, 78 Magnet 80 Vacuum pad

Claims (3)

A frame clamp device disposed on the outer periphery of a chuck table that sucks and holds a wafer mounted on an annular frame via an adhesive tape,
A support frame attached to the chuck table so as to be movable in the radial direction and immovable in the vertical direction;
A movable frame attached to the support frame so as to be movable up and down;
A suction means disposed on the movable frame and capable of sucking the annular frame of the wafer sucked and held by the chuck table;
Driving means for moving the movable frame up and down with respect to the support frame;
The driving means moves the movable frame between a pull-down position where the annular frame is pulled down from the upper surface of the chuck table, and an upper position where the upper surface of the chuck table and the lower surface of the annular frame are approximately the same height. A frame clamp device characterized by being movable.   The frame clamp device according to claim 1, wherein the attracting means is composed of a permanent magnet.   The frame clamp device according to claim 1, wherein the suction means is constituted by a vacuum pad.

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