JP2015072986A - Wafer cutting method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a wafer cutting method by which a test element is securely removed.SOLUTION: A wafer cutting method uses a cutting apparatus having a chuck table and cutting means. The wafer cutting method comprises a removal step, a dividing step, and so on. In the removal step, a first cut blade 21a whose leading end is formed in a V shape is cut to a certain point of a wafer W along a cut dividing target line L, and a TEG 200 on the dividing target line L is removed while a cut groove R is formed. In a dividing step, the wafer W is completely cut along the cut groove R with a second cutting blade, which is narrower than the width of the cut groove R, thereby dividing the waver W into a plurality of devices D. In the removal step, an amount of cut of the first cut blade 21a is set for the dividing target line L so that the maximum width of the TEG 200 for each dividing target line L of the wafer W is the removable cut groove R width.

Description

  The present invention relates to a method of cutting a division line formed on a wafer and dividing the line into individual devices.

  A wafer formed by dividing a plurality of devices such as ICs, LSIs, etc. by dividing lines is divided into individual devices by cutting the dividing lines vertically and horizontally using a cutting blade rotating at high speed. At the time of cutting, a cutting blade is positioned at the center of the planned division line, and the central portion of the planned division line is cut (see, for example, Patent Document 1).

  In addition, even when a wafer of a type in which a plurality of test elements called TEG (Test Element Group) are formed on a planned division line dividing the device is divided, the cutting blade is cut. The center part of the line to be divided is cut using the blade part including the test element. By cutting in this way, a kerf is formed at the center of the planned dividing line. Then, all the planned dividing lines are divided into individual devices by cutting similarly.

Japanese Patent Laying-Open No. 2005-311033

  However, when removing TEG with a cutting blade, if TEG is removed incompletely, TEG remaining on the surface of the wafer is peeled off, and the surface film of the wafer is also peeled off.

  The present invention has been considered in view of the above problems, and an object of the present invention is to provide a wafer cutting method capable of reliably removing a test element.

  In order to solve the above-described problems and achieve the object, a wafer cutting method of the present invention includes a chuck table for holding a wafer, and a cutting means including a cutting blade for cutting the wafer held by the chuck table. A wafer formed by dividing a plurality of devices by a predetermined division line on which a test element is formed, using a cutting device provided at least, and relatively cutting and indexing the chuck table and the cutting means; A wafer cutting method in which the division line is cut into individual devices, the first cutting blade having a V-shaped tip cut into the middle of the wafer and cut along the division line. Removing the test element on the division line while forming the cutting groove, and after performing the removing step, And dividing the wafer into a plurality of devices by completely cutting the wafer with the second cutting blade having a width smaller than the width of the cutting groove along the groove, and in the removing step, The cut amount of the first cutting blade from the surface is set for each of the division lines so as to have a cutting groove width that can remove the maximum width of the test element for each of the division lines. And

  According to the present invention, according to the width of the test element, the cutting amount of the V-shaped first cutting blade is set so as to form a cutting groove having a width capable of removing all the test elements for each division line. Since it is set, the test element can be surely removed. Further, in the present invention, when the cutting groove having a width that can remove the test element having the maximum width among the test elements formed in all the division lines is formed, the cutting groove is formed in all the division lines. As compared with, since the cutting amount in the division line without the test element can be reduced, the tip wear of the V-shaped first cutting blade can be suppressed.

FIG. 1 is a perspective view illustrating a configuration example of a cutting apparatus used in a wafer cutting method according to an embodiment. FIG. 2 is a cross-sectional view of the main part of the wafer divided into individual devices by the wafer cutting method according to the embodiment. FIG. 3 is a cross-sectional view illustrating an outline of a removing process of the wafer cutting method according to the embodiment. FIG. 4 is a cross-sectional view illustrating an outline of a dividing step of the wafer cutting method according to the embodiment. FIG. 5 is a diagram showing the width information stored in the control unit of the cutting apparatus used in the wafer cutting method according to the embodiment. FIG. 6 is a diagram showing the cutting amount information stored in the control unit of the cutting apparatus used in the wafer cutting method according to the embodiment. FIG. 7 is a diagram illustrating an image obtained by capturing an image of the planned division line before cutting. FIG. 8 is a diagram showing an image obtained by imaging the planned division line after cutting with a cut amount of 10 μm. FIG. 9 is a diagram showing an image obtained by imaging the planned division line after cutting with a cutting depth of 20 μm. FIG. 10 is a diagram showing an image obtained by imaging the planned division line after cutting with a cutting depth of 30 μm. FIG. 11 is a diagram showing an image obtained by imaging the planned division line after cutting with a cutting depth of 40 μm. FIG. 12 is a diagram showing an image obtained by imaging the planned division line after cutting with a cut amount of 46 μm.

  DESCRIPTION OF EMBODIMENTS Embodiments (embodiments) for carrying out the present invention will be described in detail with reference to the drawings. The present invention is not limited by the contents described in the following embodiments. The constituent elements described below include those that can be easily assumed by those skilled in the art and those that are substantially the same. Furthermore, the structures described below can be combined as appropriate. Various omissions, substitutions, or changes in the configuration can be made without departing from the scope of the present invention.

Embodiment
The wafer cutting method according to the embodiment will be described with reference to FIGS. FIG. 1 is a perspective view illustrating a configuration example of a cutting apparatus used in a wafer cutting method according to an embodiment. FIG. 2 is a cross-sectional view of the main part of the wafer divided into individual devices by the wafer cutting method according to the embodiment. FIG. 3 is a cross-sectional view illustrating an outline of a removing process of the wafer cutting method according to the embodiment. FIG. 4 is a cross-sectional view illustrating an outline of a dividing step of the wafer cutting method according to the embodiment. FIG. 5 is a diagram showing the width information stored in the control unit of the cutting apparatus used in the wafer cutting method according to the embodiment. FIG. 6 is a diagram showing the cutting amount information stored in the control unit of the cutting apparatus used in the wafer cutting method according to the embodiment.

  The wafer cutting method according to the embodiment (hereinafter, simply referred to as a cutting method) is a method of dividing the wafer W into individual devices D using the cutting apparatus 1 shown in FIG.

  In addition, the wafer W divided | segmented into each device D with the cutting method which concerns on this embodiment is a disk-shaped semiconductor wafer and optical device wafer which use silicon, sapphire, gallium, etc. as a base material in this embodiment. As shown in FIG. 1, the wafer W is formed by dividing a plurality of devices D by a planned division line L on which a TEG 200 (shown in FIG. 2, etc., corresponding to a test element) is formed. The TEG 200 is for inspecting the characteristics of the device D. In the wafer W, a protective film (not shown) is formed on the front surface Wa on which a plurality of devices D are formed, and a dicing tape T is attached to the back surface Wb on the back side of the front surface Wa, and the annular frame is attached to the dicing tape T. F is attached and attached to the annular frame F via the dicing tape T.

  It should be noted that the position and width of the TEG 200 formed on the planned division line L of the wafer W are appropriately set for each planned division line L. In other words, there is a scheduled division line L in which the TEG 200 is formed over the entire length, there are also scheduled division lines L in which the TEG 200 is formed at one or a plurality of locations, and there are also scheduled division lines L in which the TEG 200 is not formed at all. There is also a division line L in which a plurality of TEGs 200 having different widths are formed. In addition, there may be a plurality of scheduled division lines L in which TEGs 200 having the same width are formed at the same position in the plurality of scheduled division lines L of the wafer W, and the TEGs 200 formed on all the scheduled division lines L may be present. The position and width may be different.

  For example, in the case shown in FIG. 2, the width of the TEG 200 formed on the left planned division line L (hereinafter referred to as L1) is the same as the TEG 200 formed on the central planned division line L (hereinafter referred to as L2). It is formed larger than the width. Further, in the case shown in FIG. 2, the TEG 200 is not formed at all on the right division planned line L (hereinafter referred to as L3).

  The cutting apparatus 1 used in the cutting method includes at least a chuck table 10 that holds a wafer W and cutting means 20a and 20b that include cutting blades 21a and 21b that cut the wafer W held on the chuck table 10. As shown in FIG. 1, the cutting apparatus 1 includes two cutting means 20a and 20b (hereinafter referred to as a first cutting means and a second cutting means), that is, a 2-spindle dicer, so-called facing. This is a dual type cutting device.

  The cutting device 1 uses the first cutting means 20a to perform cutting along the division line L to form a cutting groove R (shown in FIG. 4), and then uses the second cutting means 20b to perform cutting. Cutting along the groove R to completely cut the wafer W, the wafer W is divided into a plurality of devices D. As shown in FIG. 1, in addition to the chuck table 10 and the cutting means 20a and 20b, the cutting apparatus 1 includes an X-axis moving means 30 (corresponding to a cutting feed means) and a Y-axis moving means 40 (as index feed means). Equivalent), a Z-axis moving means 50 (corresponding to a cutting feed means), and a control means 100.

  The chuck table 10 holds the wafer W that is mounted on the opening of the annular frame F via the dicing tape T on which the wafer W before cutting is placed. The chuck table 10 has a disk shape in which a portion constituting the surface is made of porous ceramic or the like, and is connected to a vacuum suction source (not shown) through a vacuum suction path (not shown) to suck the wafer W placed on the surface. Hold by. The chuck table 10 is provided so as to be movable in the X-axis direction by the X-axis moving means 30, and is provided so as to be rotatable around a central axis (parallel to the Z-axis) by a rotation drive source (not shown). Yes.

  The first cutting means 20 a and the second cutting means 20 b are for cutting while supplying the processing water to the wafer W held on the chuck table 10. The first cutting means 20a and the second cutting means 20b are provided so as to be movable in the Y-axis direction by the Y-axis moving means 40 with respect to the wafer W held on the chuck table 10, respectively, and the Z-axis The moving unit 50 is provided so as to be movable in the Z-axis direction.

  The first cutting means 20a is an ultra-thin cutting grindstone having a substantially ring shape, and includes a first cutting blade 21a that cuts the wafer W by being rotated by a spindle (not shown). Yes. The tip of the outer edge of the first cutting blade 21a has a V-shaped cross section as shown in FIG. The first cutting blade 21 a cuts the division line L of the wafer W from the TEG 200 to the middle of the wafer W in the thickness direction to form a cutting groove R having a V-shaped cross section, and from the surface of the division line L to the TEG 200. And the protective film is removed.

  The second cutting means 20b is an ultra-thin cutting grindstone having a substantially ring shape, and includes a second cutting blade 21b that cuts the wafer W by being rotated by a spindle (not shown). Yes. The tip of the outer edge of the second cutting blade 21b is formed flat as shown in FIG. The second cutting blade 21b is formed to be thinner than the thickness of the first cutting blade 21a, and is thinner than the width of the cutting groove R formed by the first cutting blade 21a. The second cutting blade 21b cuts into the cutting groove R to completely cut the wafer W.

  In addition, the axial center direction of the spindle of the two cutting means 20a and 20b of this embodiment is set in parallel with the Y-axis direction. As shown in FIG. 1, the first cutting means 20a is provided on one column portion 3a erected from the apparatus main body 2 via a Y-axis moving means 40, a Z-axis moving means 50, and the like. As shown in FIG. 1, the second cutting means 20b is provided on the other pillar portion 3b via a Y-axis moving means 40, a Z-axis moving means 50, and the like.

  The cutting means 20 a and 20 b can position the cutting blades 21 a and 21 b at arbitrary positions on the surface of the chuck table 10 by the Y-axis moving means 40 and the Z-axis moving means 50. The first cutting means 20a is fixed so that the imaging means 80 for imaging the upper surface of the wafer W moves integrally with the spindle. The imaging unit 80 includes a CCD camera that captures an area to be divided of the wafer W that is held on the chuck table 10 before the division processing. The CCD camera images the wafer W held on the chuck table 10, obtains an image for performing alignment for aligning the wafer W and the cutting blades 21 a and 21 b, and sends the obtained image to the control means 100. Output.

  The control means 100 controls the above-described components constituting the cutting device 1 to cause the cutting device 1 to perform division processing on the wafer W. The control means 100 is mainly composed of an arithmetic processing unit constituted by, for example, a CPU, a microprocessor (not shown) provided with a ROM, a RAM, etc., and a display means for displaying the state of the processing operation, the image, etc. The operator is connected to an operating means (not shown) used when the operator registers processing content information and the like.

  Further, the control means 100 has width information WI (FIG. 1) in which each division line L of the wafer W and one of the maximum widths W1, W2,... Wn of the TEG 200 formed on each division line L are associated with each other. 5) is stored. The maximum width W1, W2,... Wn of the TEG 200 indicates the width of the TEG 200 having the maximum width among the plurality of TEGs 200 when each of the plurality of TEGs 200 is formed on each division planned line L. When only one TEG 200 is formed on the planned line L, the width of the position where the width of the single TEG 200 is maximum is shown.

  Further, the control means 100 has cut amount information SI (in FIG. 6) showing the relationship between the cut amount actually processed by the first cutting blade 21a and the width of the cut groove R actually processed by the first cutting blade 21a. Is shown). For example, the cut amount information SI shown in FIG. 6 indicates that the cut amount for forming the cutting groove R having a width of A μm on the planned division line L is B μm. The cutting amount is the distance from the protective film to the tip of the first cutting blade 21a when the first cutting blade 21a cuts halfway through the wafer W.

  The control unit 100 refers to the width information WI shown in FIG. 5 when performing cutting along the planned division line L with the first cutting blade 21a of the first cutting unit 20a. The maximum width of the TEG 200 of the planned line L is extracted. The control means 100 is shown in FIG. 6 so that a value obtained by adding a predetermined value (for example, several μm) to the maximum width of the TEG 200 extracted with reference to the width information WI is the width of the cutting groove R. The first cutting blade 21a is cut halfway through the wafer W with the cut amount based on the cut amount information SI. Further, the control means 100 sets the cut amount to the minimum cut amount Dc (see FIG. 5) so that the division line L3 where the TEG 200 is not formed has a width C of the cutting groove R larger than the width of the second cutting blade 21b. 6), the first cutting blade 21a is cut halfway through the wafer W.

  In the present invention, the control means 100 stores in advance the tip angle (for example, 45 degrees or 60 degrees) of the first cutting blade 21a, and sets a predetermined value (for example, several μm) as the maximum width of the TEG 200. Even if the first cutting blade 21a is cut halfway through the wafer W while adjusting the cutting amount based on the tip angle of the first cutting blade 21a so that the added width becomes the width of the cutting groove R. Good.

  For example, the cut amount of the first cutting blade 21a in the division line L3 in which the right TEG 200 in FIG. 3 is not formed is the minimum cut amount Dc, and the minimum cut amount Dc is the left division line L1 in FIG. Is smaller than the cut amount Da and the cut amount Db at the center division planned line L2 in FIG. 3 is larger than the maximum width of the TEG 200 in the center planned division line L2 in FIG. 3, the cut amount in the left planned division line L1 in FIG. Da is larger than the cut amount Db in the center division planned line L2 in FIG. In this way, as the maximum width of the TEG 200 formed on the division lines L1, L2, L3,... Increases, the cutting amount increases, and in the case shown in FIG. Cutting amount Db> minimum cutting amount Dc.

  Next, a cutting method using the cutting apparatus 1 according to the embodiment will be described. The cutting method uses the cutting device 1 to cut the chuck table 10 and the cutting means 20a and 20b relatively in the X-axis direction and feed them in the Y-axis direction and cut the division line L of the wafer W. This is a method of dividing into individual devices D. The cutting method includes a removing process, a dividing process, and the like. In the cutting method, the operator registers the machining content information in the control means 100, and the cutting device 1 starts the machining operation when the operator gives an instruction to start the machining operation. First, in the cutting method, in the adsorption process, the operator places the wafer W on the surface of the chuck table 10 separated from the cutting means 20 a and 20 b, and the control means 100 sucks and holds the wafer W on the surface of the chuck table 10. Then, the process proceeds to the removal step.

  Next, in the removing step, the control means 100 moves the chuck table 10 downward of the cutting means 20a, 20b by the X-axis moving means 30, and the imaging means 80 fixed to the first cutting means 20a. The wafer W held on the chuck table 10 is positioned below, and the image pickup unit 80 picks up an image. The imaging unit 80 outputs information about the captured image to the control unit 100. Then, the control unit 100 executes image processing such as pattern matching for aligning the scheduled division line L of the wafer W held on the chuck table 10 with the cutting blades 21a and 21b of the cutting units 20a and 20b. Then, the relative position between the wafer W held on the chuck table 10 and the cutting means 20a, 20b is adjusted.

  Then, the control means 100 extracts the maximum width of the TEG 200 on the planned division line L to be cut first from the width information WI based on the machining content information. Then, the control means 100 rotates each of the first cutting blades 21a, and each division is performed such that a value obtained by adding a predetermined value (for example, several μm) to the maximum width of the extracted TEG 200 becomes the width of the cutting groove R. Based on the cutting amount information SI for each scheduled line L, the chuck table 10 is moved to the X-axis moving unit 30 at a predetermined cutting feed speed while the Z-axis moving unit 50 adjusts the cutting amount. Cut halfway through the wafer W. Then, by cutting feed of the chuck table 10 by the X-axis moving means 30, the first cutting blade 21a performs cutting along the division line L to form the cutting groove R, and the first cutting blade 21a schedules the division. TEG 200 on line L is removed.

  When the cutting of the division line L to be cut first is completed and the cutting groove R is formed, the control unit 100 uses the X-axis moving unit 30, the Y-axis moving unit 40, the Z-axis moving unit 50, and the rotation drive source. The chuck table 10 and the first cutting means 20a are moved relative to each other, and the cutting grooves R are sequentially formed in the respective division planned lines L. At this time, the control means 100 adjusts the cutting amount of the first cutting blade 21a based on the width information WI and the cutting amount information SI. Thus, in the removal step, the cut amount of the first cutting blade 21a from the surface is set to the division planned line L so that the maximum width of the TEG 200 for each division division line L of the wafer can be removed. It is set for each. When the cutting grooves R are formed in all the division planned lines L, the process proceeds to the division process.

  In the dividing step, after performing the removing step, the control unit 100 uses the X-axis moving unit 30, the Y-axis moving unit 40, the Z-axis moving unit 50, and the rotation driving unit, and the second cutting unit 20b and the chuck table. 10 are moved relative to each other, and the second cutting blade 21b cuts in order along the division line L. At this time, in the cutting of each division line L, as shown in FIG. 4, the wafer W is completely cut along the cutting groove R by the second cutting blade 21b having a width smaller than the width of the cutting groove R. The wafer W is divided into a plurality of devices D. And it progresses to a carrying-out process. In addition, the cutting amount of the second cutting blade 21b in the dividing step is equal in all the dividing lines L1, L2, and L3 as shown in FIG.

  In the carry-out process, the control unit 100 releases the chuck table 10 from being sucked after the chuck table 10 is retracted from below the cutting units 20a and 20b. Then, the operator removes the plurality of divided devices D and the like from the chuck table 10 and places the wafer W before cutting again on the chuck table 10, and repeats the above-described steps to remove the wafer W individually. Divide into device D.

  As described above, the cutting method according to the embodiment has a V-shaped cross section so as to form a cutting groove R having a width capable of removing all the TEGs 200 for each division planned line L according to the maximum width of the TEGs 200. The cutting amount of the first cutting blade 21a is set. For this reason, the cutting method can reliably remove the TEG 200 in the removal step. Moreover, the cutting method can reduce the cutting amount in the division | segmentation planned line L without TEG200 compared with the case where the cutting groove R of the width | variety which can remove the widest TEG200 is formed in all the division | segmentation lines L. Therefore, the tip wear of the first cutting blade 21a having a V-shaped cross section can be suppressed. Therefore, the cutting method can prevent peeling of the surface film due to incomplete removal of the TEG 200.

  Next, the inventors of the present invention confirmed the effects of the above-described embodiment. In the confirmation, the planned division line L on which the TEG 200 having the maximum width of 59 μm is formed is cut using the first cutting blade 21a with the cutting amounts of 10 μm, 20 μm, 30 μm, 40 μm, and 46 μm. Was imaged. The results are shown in the upper part of FIGS. The upper part of FIG. 7 is a diagram showing an image obtained by imaging the division line L before cutting, and the upper part of FIG. 8 is an image of the division line L after cutting with a cutting depth of 10 μm. FIG. 9 is a diagram illustrating an obtained image, and the upper part of FIG. 9 is a diagram illustrating an image obtained by imaging the planned division line L after cutting with a cut amount of 20 μm, and the upper part of FIG. It is the figure which showed the image obtained by imaging the division | segmentation planned line L after cutting with the amount set to 30 micrometers, and the upper stage of FIG. 11 is obtained by imaging the division | segmentation planned line L after cutting with the cutting amount set to 40 micrometers. The upper part of FIG. 12 is an image obtained by imaging the planned division line L after cutting with a cut amount of 46 μm. Moreover, the lower stage of FIGS. 7-12 shows the image obtained by imaging the division | segmentation planned line L in which TEG200 after cutting by the same cutting amount as the upper stage is not formed as a comparison.

  In FIG. 8, the width of the cutting groove R is about 17 μm, in FIG. 9, the width of the cutting groove R is about 31 μm, in FIG. 10, the width of the cutting groove R is about 48 μm, and in FIG. The width of R is about 72 μm, and in FIG. 12, the width of the cutting groove R is about 87 μm.

  8 to FIG. 10, when the width of the cutting groove R is smaller than the maximum width of the TEG 200, it has been clarified that the TEG 200 is peeled off at the outer edge of the cutting groove R. Further, comparing the upper and lower stages of FIG. 11, it was found that even if the width of the cutting groove R is 13 μm larger than the maximum width of the TEG 200, the TEG 200 is slightly peeled off the outer edge of the cutting groove R. On the other hand, when comparing the upper and lower stages of FIG. 12, the upper and lower images are almost equal. Therefore, by making the width of the cutting groove R 28 μm larger than the maximum width of the TEG 200, the cutting groove R It became clear that no peeling of the TEG 200 occurred on the outer edge.

  In the present invention, the cutting feed speed of the chuck table 10 by the X-axis moving means 30 in the removing process may be changed according to the maximum width of the TEG 200, and the cutting feed speed of the chuck table 10 by the X-axis moving means 30 in the dividing process. May be changed according to the width of the cutting groove R. In this case, the cutting feed rate of the chuck table 10 by the X-axis moving means 30 in the removing process may be gradually decreased as the maximum width of the TEG 200 increases, or the chuck table 10 by the X-axis moving means 30 in the dividing process. The cutting feed rate may be gradually increased as the width of the cutting groove R increases.

  In the above-described embodiment, the control unit 100 stores the width information WI and the cut amount information SI in advance. However, in the present invention, the control unit 100 previously stores each division planned line L and each of the wafers W. You may memorize | store the information which linked | related one-to-one with the cutting amount of the division | segmentation line L. FIG. Furthermore, in the present invention, the cutting amount may be calculated by extracting the maximum width of the TEG 200 on each scheduled division line L from the image obtained by the imaging unit 80.

  In addition, this invention is not limited to the said embodiment and modification. That is, various modifications can be made without departing from the scope of the present invention.

DESCRIPTION OF SYMBOLS 1 Cutting device 10 Chuck table 20a, 20b Cutting means 21a First cutting blade 21b Second cutting blade 200 TEG (test element)
W Wafer D Device L Divided line R Cutting groove

Claims (1)

A cutting apparatus including at least a chuck table for holding a wafer and a cutting means including a cutting blade for cutting a wafer held by the chuck table is used, and the chuck table and the cutting means are relatively cut and fed. A wafer cutting method in which a plurality of devices are partitioned by a dividing division line formed by indexing and feeding, and a wafer is formed by cutting the division dividing line of the wafer and dividing it into individual devices,
A removing step in which the first cutting blade having a V-shaped tip is cut halfway along the wafer and cut along the division line to form a cutting groove while removing the test elements on the division line. When,
A dividing step of performing a complete cutting of the wafer with the second cutting blade having a width narrower than the width of the cutting groove along the cutting groove after the removing step and dividing the wafer into a plurality of devices,
In the removing step, the cut amount of the first cutting blade from the surface is set for each of the division lines to be cut so that the maximum width of the test element for each of the division lines of the wafer can be removed. The wafer cutting method characterized by being set to.