JP2015061020A - Cutting equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To allow for recognition of such a state that the cutting line meanders for the cutting direction, or inclines for the thickness direction of a planar work.SOLUTION: A cutting device (1) has cutting means (4) to which a cutting blade (42) for cutting a wafer (W) held on a holding table (3) is attached rotatably, cutting feed means performing cutting feed of the cutting means and holding table relatively, and a microscope (14) for imaging a cutting line (L) along which the wafer is cut by the cutting means subjected to cutting feed by the cutting feed means. The microscope includes a differential interference microscope (15). A recognition section (28a) for recognizing the inclination of the line cut by the cutting means, by an image captured by the differential interference microscope is also provided.

Description

  The present invention relates to a cutting apparatus that cuts a cutting line into a plate-like workpiece by a rotating cutting blade.

  A cutting apparatus that divides a wafer such as a semiconductor wafer into individual devices includes a chuck table that holds the wafer, and a cutting means that rotatably supports a cutting blade that cuts a scheduled cutting line of the wafer held on the chuck table. The wafer can be divided into individual devices with high accuracy (see Patent Document 1).

  The cutting means includes, for example, a spindle unit that rotationally drives the spindle, a blade mount attached to the tip of the spindle, a cutting blade having a thin cutting blade attached to the blade mount, and a fixing that fixes the cutting blade to the blade mount. It consists of a nut.

  With such a cutting device, when cutting a disk-shaped workpiece such as a sapphire wafer, glass wafer, SiC wafer, or quartz wafer with a cutting blade, the cutting blade meanders, particularly at the beginning of the outer periphery of the wafer. Or run away.

  Therefore, in Patent Document 1, the cutting blade is cut into the wafer from the upper surface side of the wafer, and the cutting blade and the wafer are moved relative to each other in this state to cut the wafer with the cutting blade to form a cutting line.

JP 2012-121106 A

  In continuous cutting of a cutting line, depending on conditions such as the rotational speed and cutting feed speed of the cutting blade, the cutting blade that is cut and fed may meander or the cut cutting blade may be bent. In such a state of the cutting blade, the side surface of the cutting line (side surface forming both sides in the width direction) is inclined with respect to the thickness direction of the wafer. If this tilted cutting line can be detected, it is possible to take measures to eliminate the tilt of the cutting line by interrupting the cutting with the cutting blade or performing dressing of the cutting blade. Therefore, in order to be able to detect meandering of the cutting blade, it has been desired to be able to recognize the inclination in the cutting line cut by the cutting blade.

  An object of the present invention is to provide a cutting apparatus capable of recognizing such a state even when the cutting line meanders with respect to the cutting feed direction or is inclined with respect to the thickness direction of the plate-like workpiece. That is.

  The cutting device of the present invention includes a holding table that holds a plate-like workpiece, a cutting means that rotatably mounts a cutting blade that cuts the plate-like workpiece held by the holding table, the cutting means, and the holding table. A cutting device comprising: a cutting feed means for relatively cutting and feeding; and a microscope for imaging a cutting line obtained by cutting a plate-like workpiece with the cutting means cut and fed by the cutting feed means, Is provided with a differential interference microscope, the cutting blade rotating by the cutting means is positioned at a predetermined cutting depth, and a cutting line in which a plate-like workpiece is cut by the cutting means by cutting and feeding by the cutting feeding means, It is characterized by comprising a recognition unit for recognizing the inclination of the cutting line by an image captured by a differential interference microscope.

  According to this configuration, when the side surface of the cutting line is tilted, a stereoscopic effect such as a relief can be recognized in the captured image captured by the differential interference microscope according to the tilt of the cutting line. Thereby, the inclination in the side surface of the cutting line can be recognized and the presence or absence of meandering or inclination in the cutting line can be confirmed, and the cutting blade can be adjusted according to the recognized result. As a result, it becomes possible to prevent machining defects on the cutting line in the plate-like workpiece to the minimum. In particular, when a hard and transparent wafer used for an optical device is a plate-like workpiece, it becomes possible to recognize the inclination of the cutting line satisfactorily from the image of the differential interference microscope.

  According to the present invention, even when the cutting line meanders with respect to the cutting feed direction or is inclined with respect to the thickness direction of the plate workpiece, such a state can be recognized.

It is a perspective view of the cutting device concerning this embodiment. 2A is a schematic diagram illustrating an example of an image captured by the imaging unit according to the present embodiment, and FIG. 2B is a cross-sectional view taken along line AA in FIG. 2A. 3A is a schematic diagram illustrating another example of an image captured by the imaging unit, and FIG. 3B is a cross-sectional view taken along line BB in FIG. 3A. 4A is a schematic diagram illustrating another example of an image captured by the imaging unit, FIG. 4B is a cross-sectional view taken along the line CC in FIG. 4A, and FIG. 4C is a line DD in FIG. 4A. FIG.

  Hereinafter, the cutting apparatus according to the present embodiment will be described with reference to the accompanying drawings. FIG. 1 is a perspective view of the cutting apparatus according to the present embodiment, FIG. 2A is a schematic diagram illustrating an example of an image captured by the imaging unit according to the present embodiment, and FIG. It is sectional drawing which follows the -A line.

  As shown in FIG. 1, the cutting device 1 is configured to process a disk-shaped wafer W held on a holding table 3 on a housing 2 by a cutting means 4 provided above the holding table 3. ing.

  Here, the wafer W to be cut will be described. The surface of the wafer W having a disk shape is partitioned into a plurality of regions by division lines arranged in a lattice pattern, and an IC, LSI is formed in the partitioned regions. Alternatively, various devices D such as LEDs are formed. A dicing tape T is attached to the back surface of the wafer W, and the wafer W is attached to the annular frame F via the dicing tape T. As shown in FIG. 2, the dicing tape T is formed by laminating a glue layer Tb on a tape base Ta. In the present embodiment, the wafer W as the plate-like workpiece can be exemplified by a sapphire wafer, a glass wafer, a SiC wafer, and a quartz wafer, and is imaged by a differential interference microscope 15 described later, so that the workpiece is made of a transparent material. It is preferable to constitute.

  Returning to FIG. 1, a rectangular opening 2 a extending in the X-axis direction is formed on the upper surface of the housing 2, and the opening 2 a is movable with the holding table 3 and a bellows-like moving plate 31. The waterproof cover 32 is covered. Below the waterproof cover 32, a grinding feed means (not shown) for moving the holding table 3 in the X-axis direction is provided. On the surface of the holding table 3, a holding surface 33 that sucks and holds the wafer W from the back side is formed of a porous ceramic material. The holding surface 33 is connected to a suction source (not shown) through a flow path in the holding table 3. The holding table 3 has a disk shape and is provided so as to be rotatable about a disk center by a rotating means (not shown).

  The holding table 3 is reciprocated between a delivery position at the center of the apparatus and a machining position facing the cutting means 4. FIG. 1 shows a state in which the holding table 3 is waiting at the delivery position. In the housing 2, one corner portion adjacent to the delivery position is lowered by one step, and the mounting table 6 is provided at a lowered position so as to be lifted and lowered. On the mounting table 6, a cassette 5 containing a wafer W is mounted. By moving the mounting table 6 up and down while the cassette 5 is mounted, the drawing position and the pushing position of the wafer W are adjusted in the height direction.

  A pair of guide rails 7 parallel to the Y-axis direction and a push-pull mechanism 8 that conveys the wafer W between the pair of guide rails 7 and the cassette 5 are provided at the upper right side of the mounting table 6 in FIG. ing. The pair of guide rails 7 guide the conveyance of the wafer W by the push-pull mechanism 8 and position the wafer W in the X-axis direction. The push-pull mechanism 8 is configured to pull out the unprocessed wafer W from the cassette 5 to the pair of guide rails 7 and to push the processed wafer W into the cassette 5 from the pair of guide rails 7. The push-pull mechanism 8 positions the wafer W in the Y-axis direction.

  In the vicinity of the pair of guide rails 7, a first transport arm 11 that transports the wafer W between the guide rails 7 and the holding table 3 is provided. The wafer W is transported when the L-shaped arm portion 16 of the first transport arm 11 is turned. Further, a spinner type cleaning mechanism 12 is provided on the right side of the holding table 3 at the delivery position in FIG. In the cleaning mechanism 12, the cleaning water is sprayed toward the rotating spinner table 17 to clean the wafer W, and then the dry air is blown instead of the cleaning water to dry the wafer W.

  A support base 22 is provided on the housing 2, and a cantilever support portion 25 is provided on the support base 22 so as to cross over the movement path of the holding table 3. The cantilever support part 25 supports the cutting means 4 and the microscope 14 so as to be positioned above the holding table 3. The cutting means 4 and the microscope 14 are moved in the Y-axis direction and the Z-axis direction by a ball screw type moving mechanism (not shown) incorporated in the support base 22 and the cantilever support portion 25.

  The cutting means 4 has a cutting blade 42 provided at the tip of a spindle (not shown). The cutting blade 42 is covered with a blade cover 43, and the blade cover 43 is provided with an injection nozzle 44 that injects cutting water toward the cutting portion. In the cutting means 4, the cutting line L (see FIG. 2) is formed by rotating the cutting blade 42 at a high speed and cutting the wafer W while spraying cutting water from the spray nozzle 44. Here, by forming the cutting line L, a pair of side surfaces serving as edges of the cutting line L are formed on both sides in the width direction (left and right direction in FIG. 2). In this embodiment, the left edge in FIG. The side surface L1 and the right edge in FIG. 2 are defined as a second side surface L2.

  The microscope 14 is constituted by a differential interference microscope 15. The differential interference microscope 15 employs a structure that enables imaging of the wafer W by differential interference that visualizes phase information of the transparent wafer W with contrast of interference colors by polarization interference. In the differential interference method, light from a light source is converted into linearly polarized light, and then separated into two linearly polarized light having vibration directions orthogonal to each other, and these two lights are transmitted through two slightly different points on the wafer W. The light passing through these two different points has a phase difference due to the difference in the refractive index of the medium and the difference in the path length. After undergoing deformation of the wavefront, the two wavefronts are matched by combining them after matching them. Interference corresponding to the deviation occurs. At this time, the contrast of the interference color corresponding to the phase shift (differential coefficient of the transmitted wavefront) is added, and the captured image by the differential interference can have a three-dimensional feeling like a relief. Therefore, as shown in FIG. 2A, when the surface area of the wafer W including the formation position of the cutting line L is imaged, not only the forming edge of the cutting line L on the surface of the wafer W but also the side surfaces L1 and L2 of the cutting line L The direction of inclination and the formation position can be recognized. In FIG. 2A, a relief-like three-dimensional effect is schematically represented by a plurality of lines. However, in an actual captured image, it appears in a gradation according to the inclination of each side face L1, L2 and the thickness direction of the wafer W. (The same applies to FIGS. 3A and 4A described later).

  A second transfer arm 13 that transfers the wafer W between the holding table 3 and the cleaning mechanism 12 is provided on the side surface 23 of the support base 22. The arm portion 18 of the second transfer arm 13 extends obliquely forward, and the wafer W is transferred by moving the arm portion 18 in the Y-axis direction.

  At the foremost part of the housing 2, input means 26 is provided for receiving instructions to various parts of the apparatus. A monitor 27 is arranged on the upper surface of the support base 22. On the monitor 27, processing conditions of the wafer W, notification contents to the operator, and the like are displayed. Further, in the housing 2, a control unit 28 that controls each part of the cutting device 1 is provided. Various instructions are input to the control means 28 from the input means 26, and operations of components such as the holding table 3 and the cutting means 4 of the cutting apparatus 1 are controlled based on the various instructions. The control means 28 is configured by a processor, a memory, and the like that operate each component of the cutting device 1. The memory is composed of one or a plurality of storage media such as a ROM (Read Only Memory) and a RAM (Random Access Memory) depending on the application.

  The control unit 28 includes a recognition unit 28a and a pattern determination unit 28b. The recognizing unit 28a recognizes the inclinations of the side surfaces L1 and L2 in the cutting line L from the captured image of the differential interference microscope 15. The pattern determination unit 28b selects any one of several types of instruction patterns for the operator prepared for eliminating the inclination based on the inclinations of the side surfaces L1 and L2 of the cutting line L recognized by the recognition unit 28a.

  Next, a method for cutting the wafer W by the above-described cutting apparatus 1 will be described. First, the wafer W mounted on the frame F is taken out from the cassette 5 through the dicing tape T, and the wafer W is conveyed onto the holding table 3 with the surface of the wafer W facing upward and the dicing tape T positioned below the wafer W. And placed on the holding surface 33. Thereafter, the holding surface 33 communicates with a suction source (not shown), and the wafer W mounted on the frame F via the dicing tape T is sucked and held by the holding table 3.

  After the wafer W is sucked and held, the cutting means 4 is moved in the Y-axis direction so that the planned division line of the wafer W and the position of the cutting blade 42 in the Y-axis direction coincide with each other. Next, the cutting means 4 is moved in the Z-axis direction, and the cutting blade 42 is positioned in the Z-axis direction so that the depth of the cutting line L reaches halfway in the thickness direction of the dicing tape T. Thereafter, the holding table 3 is cut and fed relative to the cutting blade 42 rotated at a high speed in the X-axis direction, so that a cutting line L is formed along the planned division line of the wafer W parallel to the X-axis. The Then, each time one cutting line L is formed, the cutting means 4 is moved in the Y-axis direction of the wafer W by the pitch interval in the Y-axis direction of the division line, and the cutting line L is repeated by repeating the same operation. Are sequentially formed. In the wafer W, after the cutting lines L are formed on all the division lines that are parallel to the X axis, the holding table 3 is rotated by 90 °. From this state, the cutting lines L are formed on all the planned dividing lines in the lattice shape by forming the cutting lines L on all the dividing lines parallel to the X axis in the same manner as described above.

  As described above, when the cutting operation of the cutting line L is continued, the cut cutting blade 42 may be bent or the cutting line L may meander in the X-axis direction. In such a case, the side surfaces L1 and L2 of the cutting line L are inclined with respect to the thickness direction (Z-axis direction) of the wafer. The cutting line L is imaged by the differential interference microscope 15 in order to recognize the inclination in each of the side surfaces L1 and L2. The timing at which such imaging is performed can be exemplified as being regular, such as every time several wafers W are cut or every time several cutting lines L are cut. Alternatively, the movement of the cutting means 4 in the X-axis direction may be extended at an arbitrary timing for cutting the cutting line L, and imaging may be performed immediately after the cutting of each cutting line L. Hereinafter, an imaging method of the cutting line L and a captured image processing method will be described.

  In imaging of the cutting line L, after the cutting operation of the cutting line L is temporarily stopped, the cutting line L is positioned directly below the differential interference microscope 15 so that the cutting line L enters the visual field of the differential interference microscope 15. Then, in the differential interference microscope 15, the cutting line L and the surface area of the wafer W that is the periphery of the cutting line L are captured as captured images as shown in FIGS. 2A, 3A, and 4A, for example. The captured image captured by the differential interference microscope 15 is input to the recognition unit 28 a of the control unit 28. In the recognizing unit 28a, the input captured image is analyzed, and whether or not there is an inclination in each of the side surfaces L1, L2 of the cutting line L is confirmed. If the recognition unit 28a recognizes that the side surfaces L1 and L2 are not inclined, the cutting operation of the cutting line L is resumed.

  On the other hand, when the recognition unit 28a recognizes that the side surfaces L1 and L2 of the cutting line L are inclined, the inclination direction and the inclination of the first side surface L1 and the second side surface L2 from the captured image of the differential interference microscope 15, respectively. The position of the location where the is formed is recognized. 2A, both the first side face L1 and the second side face L2 are directed toward the dicing tape T side over substantially the entire extending direction of the cutting line L. In FIG. A slope inclined in the middle right direction is recognized. In the captured image of FIG. 3A, the inclined surface (see FIG. 3B) is inclined so that the first side face L1 and the second side face L2 gradually move away toward the dicing tape T side over substantially the entire extending direction of the cutting line L. Be recognized. In the captured image of FIG. 4A, the cutting line L extends in a meandering direction. Therefore, both the first side face L1 and the second side face L2 are formed by a slope inclined rightward as shown in FIG. 4B toward the dicing tape T side and a slope inclined leftward as shown in FIG. It is recognized alternately in the extending direction.

  The data certified by the certification unit 28a as described above is output to the pattern determination unit 28b. The pattern determination part 28b selects the display content to the operator by the monitor 27 based on the inclination of each side face L1, L2 of the cutting line L recognized by the recognition part 28a. For the captured image in FIG. 2A, notification content that prompts replacement of the cutting blade 42 is selected. For the captured image of FIG. 3A, notification content that prompts dressing of the cutting blade 42 is selected. For the captured image in FIG. 4A, notification content that prompts the cutting feed rate of the cutting blade 42 to be reduced is selected. The notification content selected by the pattern determination unit 28 b is displayed on the monitor 27. The operator who has confirmed the monitor 27 performs the replacement of the cutting blade 42 and various adjustments according to the notification content displayed on the monitor 27. In addition, said alerting | reporting content is an example and is not restricted to this.

  As described above, according to the present embodiment, the side surfaces L1 and L2 of the cutting line L are imaged by the differential interference microscope 15, so that the inclination direction and the like on the side surfaces L1 and L2 can be recognized. And from the recognized result, it becomes possible to adjust the cutting blade 42 so that the normal cutting line L can be cut by correcting the inclinations of the side surfaces L1 and L2, and the cutting failure of the cutting line L is prevented from occurring. be able to.

  In addition, when the cutting line L is imaged with a conventional microscope, for example, the focus range in the thickness direction of the wafer W is extremely small. For example, when the microscope is focused on the upper surface of the wafer W, the position is lower than the upper surface. Then it becomes out of focus. Therefore, in order to recognize the inclinations of the side surfaces L1 and L2 of the cutting line L, it is necessary to perform detection at a plurality of locations from the upper surface to the lower surface of the wafer W. For this reason, not only the detection of the cutting line L is performed a plurality of times, but also the focusing needs to be performed a plurality of times, and there is an inconvenience that it takes a long time to recognize the inclinations of the side surfaces L1 and L2 of the cutting line L. . In this respect, in the present embodiment, since it is not necessary to perform focusing a plurality of times, it is possible to shorten the time required for imaging the cutting line L and to improve efficiency. In addition, since the differential interference microscope 15 can recognize a three-dimensional effect such as a relief according to the inclination of the cutting line L, the angle of inclination and the formation region can be recognized with higher precision than in the case of imaging with a conventional microscope. .

  In addition, this invention is not limited to the said embodiment, It can change and implement variously. In the above-described embodiment, the size, shape, and the like illustrated in the accompanying drawings are not limited to this, and can be appropriately changed within a range in which the effect of the present invention is exhibited. In addition, various modifications can be made without departing from the scope of the object of the present invention.

  For example, the pattern determination unit 28 b in the control unit 28 may be omitted, and a captured image captured by the differential interference microscope 15 may be displayed on the monitor 27. In this case, a recognition unit is configured by the monitor 27, and an operator who views the captured image of the monitor 27 can select a response such as replacement of the cutting blade 42.

  In the above embodiment, the holding table 3 is moved by the grinding feed means (not shown). Instead, only the grinding means 4 is moved, or the grinding means 4 and the holding table 3 are moved. Both may be configured to move so that the grinding means 4 and the holding table 3 move relative to each other.

  As described above, the present invention has an effect of being able to recognize meandering and inclination of a cutting line formed by cutting a plate-like workpiece, and in particular, cutting the cutting line with a rotating cutting blade. Useful for cutting equipment.

DESCRIPTION OF SYMBOLS 1 Cutting device 3 Holding table 4 Cutting means 14 Microscope 15 Differential interference microscope 28a Recognition part 42 Cutting blade L Cutting line W Wafer (plate-shaped workpiece)

Claims (1)

A holding table for holding a plate-like workpiece, a cutting means for rotatably mounting a cutting blade for cutting the plate-like workpiece held by the holding table, and the cutting means and the holding table are relatively cut and fed. A cutting apparatus comprising: a cutting feed means; and a microscope for imaging a cutting line obtained by cutting a plate-like workpiece with the cutting means cut and fed by the cutting feed means,
The microscope comprises a differential interference microscope,
An imaging image in which a cutting line in which the cutting blade rotating by the cutting means is positioned at a predetermined cutting depth and cut by the cutting feed means to cut a plate-like workpiece by the cutting means is imaged by the differential interference microscope. The cutting device provided with the recognition part which recognizes the inclination of this cutting line by.

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