JP2009206362A - Method of cutting plate-like material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cutting method of a plate-like material for preventing a street from being cut while the position of a cutting blade deviates. <P>SOLUTION: In the method of cutting the plate-like material, a cutting apparatus is used. The cutting apparatus has: a chuck table; a cutting means to which the cutting blade 28 is attached; an alignment means having an optical system in which a reference line 84 for aligning the cutting blade is formed; a blade detection means for detecting distance to the cutting blade; and a control means for storing the position of the reference line 84 and the distance to the cutting blade 28 and controlling the cutting feed of the cutting blade. When a plurality of scheduled cutting positions are cut while index-feeding the cutting means in a state, where the scheduled cutting position has been aligned to the reference line once, distance (d) to the cutting blade is detected by the blade detection means, the position of the cutting blade is corrected by (d-D) to cut the plate-like material to distance D between the reference line 84 measured in advance and the blade detection means. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a cutting method of a plate-like object for cutting a plate-like object such as a semiconductor wafer.

  Semiconductor wafers in which a plurality of electronic circuits such as IC and LSI are formed on a silicon substrate, and various plate materials such as various ceramic substrates, resin substrates, and glass substrates used for electronic components are individually processed by a dicing device (cutting device). Divided into chips, it is widely used in various electronic devices.

  In the cutting process of a plate-like object by a dicing device, the processing position is set by matching a camera reference line generally called a hairline with a planned cutting line. At that time, an operation (hairline alignment) of aligning the reference line of the camera with the center line of the cutting blade is performed in advance.

  Specifically, this hairline alignment operation is performed by processing a groove on the surface of the workpiece once with a cutting blade, imaging the processed groove, performing image processing, and detecting the center of the processed groove. By calculating the amount of deviation between the position and the reference line position of the camera, and adding or subtracting this deviation amount to the coordinate position, the origin position that matches the center position of the machining groove and the reference line position of the camera is stored in the device. Is going on.

  If the cutting is continued, thermal expansion occurs in the spindle as the spindle mounted with the cutting blade rotates at a high speed. This thermal expansion causes an axial shift in the position of the cutting blade. Due to this misalignment, there is a problem that the cutting blade cuts the position off the planned cutting line (street), thereby damaging the device region and reducing the quality.

  Therefore, with a normal dicing machine, the processing grooves formed on the wafer, which is the workpiece, are periodically photographed with the camera during cutting, and the deviation between the camera reference line and the machining groove is detected, and the deviation is taken into account. Therefore, the movement of the cutting blade is controlled.

Japanese Patent Laid-Open No. 2005-311033 discloses that, apart from cutting of a plate-like object, a cutting blade is cut into a plate-like object non-existing region to form a cutting flaw, and the cutting flaw is detected by an alignment means. A method of detecting a positional deviation of a cutting blade for detecting a positional deviation between a cutting flaw and a reference line is disclosed.
Japanese Patent Laying-Open No. 2005-311033 JP 2005-197492 A

  However, in the conventional method of correcting the cutting position of the cutting blade by photographing the groove formed on the wafer, which is a workpiece, periodically during the cutting, and correcting the cutting position of the cutting blade, The device region may be damaged at least in a part of the wafer.

  In the method disclosed in Patent Document 1, there is no fear of damaging the device area of the wafer in order to cut the plate-like object non-existing area, but it is necessary to perform air blowing in order to photograph the cutting flaws during the cutting. In addition, there is a problem that cutting dust floating in the cutting water adheres to the wafer by performing air blow. Furthermore, since processing is periodically interrupted, there is a problem that processing efficiency is poor.

  The present invention has been made in view of the above points, and the object of the present invention is to cut a planned cutting line in a state where the displacement of the cutting blade has occurred, and to form a plate-like material during the processing. It is an object of the present invention to provide a method for cutting a plate-like object that does not require air blow and that does not reduce the processing efficiency.

  According to the present invention, a chuck table for holding a plate-like object, a cutting means on which a cutting blade for cutting the plate-like object held on the chuck table is rotatably mounted, and a reference line for alignment of the cutting blade Alignment means for detecting the planned cutting position of the plate-shaped object, and blade detection means for detecting the distance to the cutting blade disposed on one side in the rotational axis direction of the cutting blade Cutting the plate-like object by using a cutting device having a control means for storing the position of the reference line and the distance to the cutting blade detected by the blade detecting means and controlling the cutting feed of the cutting blade. A cutting method, wherein an interval between the reference line and the blade detection unit is set to D, alignment between the planned cutting position and the reference line is performed, and the planned cutting position and the reference line In a state where the alignment is performed once, when cutting a plurality of the planned cutting positions while indexing the cutting means at every planned cutting position interval, the blade detecting means detects the distance d to the cutting blade, A plate shape comprising the steps of cutting a plate-like object by correcting the position of the cutting blade by (d−D) with respect to the interval D between the reference line and the blade detecting means. An object cutting method is provided.

  According to the present invention, since the machining groove is not required to detect the positional deviation of the cutting blade, the cutting process is not performed in a state where the positional deviation has occurred in the cutting blade, which may damage the device region. Absent. Moreover, since it is not necessary to dry the plate-shaped object which is a to-be-processed object by air blow, there is no possibility that cutting waste will adhere to a plate-shaped object by air blow.

  Furthermore, since the position of the cutting blade can be detected at any time during the machining by the blade detecting means and the position deviation can be corrected, the machining efficiency is not reduced without interrupting the cutting.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 shows an appearance of a cutting apparatus 2 according to an embodiment of the present invention, which can divide a semiconductor 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 It is attracted by the transport means 16 and transported onto the chuck table 18 and is sucked by the chuck table 18, and is held on the chuck table 18 by fixing the frame F by a plurality of fixing means 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 (optical system) 22 such as a CCD camera that images the surface of the wafer W, and detects a street to be cut by processing such as pattern matching based on an image acquired by imaging. Can do. 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 approximately located on the extension line in the X-axis direction of the alignment reference line (hairline) of the imaging means 22.

  Referring to FIG. 3, an exploded perspective view showing the relationship between the spindle and the blade mount attached to the spindle is shown. A spindle 26 that is rotationally driven by a servo motor (not shown) is rotatably accommodated in a spindle housing 32 of the spindle unit 30. The spindle 26 has a tapered portion 26a and a tip small diameter portion 26b, and a male screw 34 is formed on the tip small diameter portion 26b.

  A blade mount 36 includes a boss part (convex part) 38 and a fixed flange 40 formed integrally with the boss part 38, and a male screw 42 is formed on the boss part 38. Further, the blade mount 36 has a mounting hole 43.

  In the blade mount 36, the mounting hole 43 is inserted into the tip small diameter portion 26b and the tapered portion 26a of the spindle 26, and the nut 44 is screwed into the male screw 34 and tightened, so that the tip end portion of the spindle 26 as shown in FIG. Attached to.

  FIG. 4 is an exploded perspective view showing the mounting relationship between the spindle 26 to which the blade mount 36 is fixed and the cutting blade 28. The cutting blade 28 is called a hub blade, and is configured by electrodepositing a cutting blade 50 in which diamond abrasive grains are dispersed in a nickel base material on the outer periphery of a circular base 46 having a circular hub 48.

  By inserting the mounting hole 52 of the cutting blade 28 into the boss portion 38 of the blade mount 36 and screwing the fixing nut 54 into the male screw 42 of the boss portion 38 and tightening, the cutting blade 28 is moved to the spindle 26 as shown in FIG. Attached to.

  Referring to FIG. 6, an enlarged perspective view of the cutting means 24 with the cutting blade 28 attached thereto is shown. A blade cover 60 covers the cutting blade 28, and a cutting water nozzle (not shown) that extends along the side surface of the cutting blade 28 is attached to the blade cover 60. Cutting water is supplied to a cutting water nozzle (not shown) via the pipe 72.

  Reference numeral 62 denotes a detachable cover, which is attached to the blade cover 60 with screws 64. The detachable cover 62 has a cutting water nozzle 70 that extends along the side surface of the cutting blade 28 when attached to the blade cover 60. The cutting water is supplied to the cutting water nozzle 70 via the pipe 74.

  A blade detection block 66 is attached to the blade cover 60 with screws 68. As shown in FIG. 7, blade detection means 80 for detecting the distance to the cutting blade 28 is attached to the blade detection block 66 so as to be positioned on one side in the rotation axis direction of the cutting blade 28.

  Preferably, the blade detection means 80 is attached to the back side (left side in FIG. 7) of the apparatus as shown. This is because it is easy to avoid contact between the cutting edge 50 of the cutting blade 28 and the blade detecting means 80 when the cutting blade 28 is replaced.

  As the blade detection means 80, for example, a capacitance sensor, an eddy current meter, a laser interferometer, or the like can be employed. Since the blade detection block 66 is attached to a blade cover 60 fixed to the spindle housing 32, and the imaging means 22 such as a CCD camera is fixed to the spindle housing 32, the positions of the imaging means 22 and the blade detection means 80 are fixed. The relationship is always constant.

  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 immediately below the imaging means (optical system) 22.

  When the wafer W is positioned almost directly below the imaging means 22, the surface of the wafer W is imaged by the imaging means 22, and the controller moves while moving the chuck table 18 in the X-axis direction and moving the imaging means 22 in the Y-axis direction. In the controller, pattern matching between the street image stored in advance and the actual image acquired by the imaging means 22 is performed, and the street S1 or S2 which is the planned cutting area formed on the surface of the wafer W is detected. The

  The image pickup means 22 has a reference line for blade alignment in advance, and in pattern matching, software adjustment is performed so that the center of the detected street S1 or S2 to be cut matches the reference line. .

  That is, generally, since the reference line and the Y coordinate of the cutting blade 28 mounted on the blade mount 36 do not completely coincide with each other, the deviation amount in the Y-axis direction between the reference line and the cutting blade 28 is stored in the controller as a correction value. In addition, by adjusting the correction value, the center of the street S1 or S2 and the reference line are matched.

  In the present embodiment, when the blade detection block 66 is fixed to the blade cover 60 during assembly of the apparatus, the positional relationship in the Y-axis direction between the blade detection unit 80 and the reference line 84 of the imaging unit 22 is fixed. An interval D between the means 80 and the reference line 84 is set, and this interval D is stored in the memory of the controller. This distance D is always constant as long as the blade detection block 66 is fixed to the blade cover 60. Reference numeral 82 denotes a field of view of the imaging means 22.

  Further, when a new cutting blade 28 is mounted on the blade mount 36, the blade detection means 80 detects the distance d1 from the blade detection means 80 to the cutting blade 28, and this d1 is also stored in the memory of the controller.

  As described above, when the cutting blade 28 is attached to the blade mount 36, generally the coordinates in the Y-axis direction between the reference line 84 and the cutting blade 28 do not completely coincide. Therefore, although D = d1 is not physical, the deviation amount in the Y-axis direction between the reference line 84 and the cutting blade 28 is stored as a correction value in the controller, and the correction value is adjusted to increase or decrease the planned cutting position. The center position of (street) and the reference line 84 are aligned by software. That is, correction is performed so that d1-D becomes zero.

  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.

  As shown in FIG. 8, the streets S1 in the same direction are all cut by performing cutting while the cutting means 24 is index-fed in the Y-axis direction by the street pitch stored in the memory. 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 cleaning, while rotating the wafer W at a high speed (for example, 3000 rpm), air is blown out from the air nozzle to dry the wafer W, and then the wafer W is sucked by the conveying means 16 and returned to the temporary storage area 12, and further carried in and out. By means 10, the wafer W is returned to the original storage location of the wafer cassette 8.

  When the cutting is continued, the spindle 26 is thermally expanded due to the high-speed rotation of the spindle 26, and as shown in FIG. 9B, the cutting blade 28 attached to the spindle 26 is displaced in the Y-axis direction.

  The distance d from the blade detection means 80 to the cutting blade 28 changes as the thermal expansion occurs. In this embodiment, since the changing distance d is detected constantly or as needed, the spindle 26 extends due to thermal expansion. When the position of the cutting blade 28 is displaced, the cutting blade 28 can be positioned at the center of the street S1 or S2 by correcting the position of the cutting blade 28 by (d−D). Such correction of the positional deviation of the cutting blade 28 may be always performed at the start of cutting, or may be periodically performed.

  According to the above-described embodiment, since it is not necessary to form a cutting groove as in the prior art in order to detect the positional deviation of the cutting blade 28, the cutting of the wafer W is performed in a state where the positional deviation occurs in the cutting blade 28. Is prevented. Moreover, since it is not necessary to blow off the cutting water near the cutting groove by air blow, the cutting waste does not adhere to the wafer W.

  Further, since the position detection of the cutting blade 28 can be detected at any time during the cutting process by the blade detection means 80 and the position shift can be corrected, the processing does not need to be interrupted and the processing efficiency is not lowered.

It is an appearance perspective view of a cutting device concerning an embodiment of the present invention. It is a perspective view which shows the wafer integrated with the flame | frame. It is a disassembled perspective view which shows the relationship between a spindle unit and the blade mount which should be fixed to a spindle. It is a disassembled perspective view which shows the relationship between a spindle unit and the cutting blade which should be mounted | worn with a spindle. It is a perspective view in the state where a cutting blade was attached to a spindle. It is an expansion perspective view of a cutting means. It is a figure which shows the positional relationship of a cutting blade and a blade detection means. It is a perspective view which shows a mode that a wafer is cut along a street with a cutting blade. It is explanatory drawing for demonstrating the cutting method of this invention.

Explanation of symbols

2 Cutting device 18 Chuck table 24 Cutting means 26 Spindle 28 Cutting blade 30 Spindle unit 36 Blade mount 40 Fixing bracket 54 Fixing nut 66 Blade detection block 80 Blade detection means 84 Reference line for alignment (hairline)

Claims (1)

A chuck table for holding a plate-like object, a cutting means on which a cutting blade for cutting the plate-like object held on the chuck table is rotatably mounted, and an optical in which a reference line for alignment of the cutting blade is formed An alignment means for detecting a planned cutting position of a plate-like object, a blade detection means for detecting a distance to the cutting blade disposed on one side in the rotation axis direction of the cutting blade, and a reference line A cutting method for cutting a plate-like object using a cutting device that stores a position and a distance to the cutting blade detected by the blade detecting means and includes a control means for controlling the cutting feed of the cutting blade. And
Set the distance between the reference line and the blade detection means to D,
Perform alignment between the planned cutting position and the reference line,
When cutting the plurality of scheduled cutting positions while indexing the cutting means at each scheduled cutting position interval while the alignment between the scheduled cutting position and the reference line has been performed once, the blade detecting means Detect the distance d to the cutting blade,
Cutting the plate-like object by correcting the position of the cutting blade with (d−D) with respect to the interval D between the reference line and the blade detecting means,
A method for cutting a plate-like object comprising each step.

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