JP6120644B2 - Cutting groove detection method - Google Patents

Description

  The present invention relates to a method for detecting an edge of a cutting groove of a workpiece formed by cutting.

  Conventionally, a cutting device (dicing device) for dividing a semiconductor wafer, a glass substrate, a resin substrate or the like into device chips is known. For example, as disclosed in Patent Document 1, it has two spindle units. Two spindle cutting devices are also known.

  In such a two-spindle cutting apparatus, first, a half-cut is formed by forming a groove of a predetermined depth by the cutting blade of one spindle unit, and then the groove half-cut by the cutting blade of the other spindle unit is completely cut. A step cut such as performing a full cut is performed.

  Such a step cut is also performed when a test metal pattern called a test element group (TEG) is removed from a street where a division planned line is set when cutting a semiconductor wafer.

  That is, the TEG is first removed (half cut) with the cutting blade of one spindle unit to form the first cutting groove, and then the cutting blade of the other spindle unit is moved to the position of the first cutting groove. The second cutting groove is formed to completely cut the semiconductor wafer (full cut).

  By performing such a step cut, the TEG is removed in advance by a half cut, and a full cut is performed with a cutting blade different from the cutting blade used in the half cut. No clogging due to TEG occurs.

  Then, by preventing the cutting blade that performs full cutting from being clogged by TEG, it is possible to effectively prevent chipping from occurring on the back side of the wafer.

  On the other hand, the position of the cutting groove needs to be accurately detected and controlled by the cutting device for the purpose of aligning with the street and aligning the positions of the grooves of the two cutting blades.

  For this reason, for example, as disclosed in Patent Document 2, a deviation amount for alignment is detected based on a captured image of the upper surface of the wafer, and a predetermined value is accurately cut by adjusting a correction value. I have to. In Patent Document 2, a cutting flaw is formed by cutting into a region (dicing tape) where no wafer exists, and the amount of deviation is detected based on the cutting flaw.

JP 2003-173986 A Japanese Patent Laying-Open No. 2005-311033 JP 2005-197492 A

  When performing the above-mentioned step cut, it is necessary to accurately position the cutting blade at the position of the first cutting groove formed by removing the TEG and form the second cutting groove. For this reason, it is necessary to confirm the positional relationship of a 1st cutting groove and a 2nd cutting groove suitably.

  Here, about the 1st cutting groove, the edge (boundary part) of a groove | channel can be easily recognized by applying light from the upper surface and imaging. The reason is considered that the first cutting groove has an edge on the surface of the wafer and is easily exposed to light.

  On the other hand, the second cutting groove formed at the bottom of the first cutting groove is not easily exposed to light because the edge is at the bottom of the first cutting groove deeply dug. There was a problem that the edge (boundary portion) was difficult to recognize.

  Here, as in Patent Document 2, a method may be used in which a cutting flaw is formed on a portion other than the bottom of the first cutting groove with a cutting blade that forms the second cutting groove, and this cutting flaw is detected. Although it is conceivable, it is necessary to form a cutting flaw for detection separately, which requires additional man-hours. There is also a concern that the formation of the additional cutting flaws may cause clogging of the cutting blade.

  Further, as described in Patent Document 3, the groove of the first cutting blade in which the first cutting groove is formed is detected, and separately from the detection of the position of the first cutting blade, the second cutting groove is formed. There is also a technique of detecting the position of the second cutting blade by cutting the street with TEG (metal pattern for test) with the second cutting blade to form and detecting the cutting groove of the second cutting blade. However, there is a problem in that the effect of suppressing clogging by not cutting the TEG is reduced.

  The present invention has been made in view of the above problems, and the object of the present invention is to make it possible to reliably detect the edge of the second cutting groove formed at the same location as the first cutting groove. Is to provide a new technology.

According to the present invention, there is provided a method for detecting a cutting groove, comprising: an adhesive layer, a base material layer, and a reflective material layer on the back side of a plate-shaped workpiece , wherein the reflective material layer is at least the workpiece. A dicing tape adhering step for adhering a dicing tape disposed in a region where the material is adhered , and after the dicing tape adhering step, the workpiece is held on a chuck table via the dicing tape. A first cutting step for forming, after the holding step, a first cutting groove having a depth that does not reach the back surface on the surface of the workpiece held on the chuck table by the first cutting blade; After the first cutting step, a second cutting groove having a thickness smaller than that of the first cutting blade is formed on the second cutting groove extending from the bottom of the first cutting groove to the back surface of the workpiece. Forming in the second cutting step Then, after the second cutting step, the first and second cutting grooves are imaged from the surface side while irradiating light from the surface side of the workpiece. Detecting the edge of the cutting groove, and detecting the edge of the first cutting groove by imaging the surface of the workpiece illuminated by the irradiated light. The reflected light is reflected by the reflector layer through the first cutting groove and the second cutting groove, and the second cutting groove illuminated from the back side by the reflected light is imaged from the front surface side. And the edge of this 2nd cutting groove is detected, The cutting groove detection method characterized by the above-mentioned is provided.

  In the dicing tape and the cutting groove detection method of the present invention, the second cutting groove can be illuminated with reflected light from the back surface side by using the dicing tape provided with the reflective material layer. It becomes possible to detect the edge of the cutting groove.

  Further, unlike the prior art, it is not necessary to cut a detection groove that is used only for positioning of the cutting blade, and clogging of the cutting blade can be suppressed.

It is a perspective view of the processing apparatus (cutting apparatus) suitable for implementation of this invention. (A) is a figure explaining a dicing tape sticking step. (B) is a figure shown about the state which stuck the wafer to the dicing tape. It is a figure explaining the cross section of a dicing tape. It is a figure explaining the process of a 1st cutting groove and a 2nd cutting groove. (A) is sectional drawing of the wafer after a half cut. (B) is a sectional view of the wafer after full cut. It is a figure explaining the imaging by an imaging device. It is a figure shown about an example of the captured image in which an edge appears notably.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. As an example of the processing apparatus, an external perspective view of a semiconductor wafer cutting apparatus 1 is shown in FIG.

  The cutting apparatus 1 cuts the wafer W by relatively moving the cutting units 20a and 20b (cutting means) having cutting blades and the chuck table 10 holding the wafer W to be processed. .

  As shown in FIG. 2 (B), a plurality of devices 15 are arranged in a lattice pattern on the surface Wa of the wafer W, so that the division lines 13 orthogonal to each other are formed between the devices 15. It has become. By cutting along the division line 13, it is divided into individual device chips.

  As shown in FIG. 1, the cutting device 1 is a so-called facing dual type dicer having two spindles, and has a configuration in which machining is automatically controlled by a control device 90. A gate-shaped column 3 is provided on the apparatus main body 2, and the column 3 includes two Y-axis moving devices 30a and 30b (Y-axis moving means) that move in the Y-axis direction, and Y-axis movement. Z-axis moving devices 40a and 40b (Z-axis moving means) that move in the Z-axis direction are provided in the devices 30a and 30b, respectively, and cutting units 20a and 20b are provided in the Z-axis moving devices 40a and 40b, respectively. Yes.

  The Y-axis moving device 30a is configured to move the Y-axis moving base 6a in the Y-axis direction by rotating the ball screw 31a by the Y-axis pulse motor 32a. The Z-axis moving device 40a is configured to move the support member 5a of the cutting unit 20a in the Z-axis direction by the Z-axis pulse motor 42a. With this configuration, the cutting unit 20a moves in the Y-axis direction by driving the Y-axis pulse motor 32a, and moves in the Z-axis direction by driving the Z-axis pulse motor 42a.

  Similarly, the Y-axis moving device 30b is configured to move the Y-axis moving base 6b in the Y-axis direction by rotating the ball screw 31b by the Y-axis pulse motor 32b. The Z-axis moving device 40b is configured to move the support member 5b of the cutting unit 20b in the Z-axis direction by the Z-axis pulse motor 42b. With this configuration, the cutting unit 20b moves in the Y-axis direction by driving the Y-axis pulse motor 32b, and moves in the Z-axis direction by driving the Z-axis pulse motor 42b.

  The two cutting units 20a and 20b are arranged so as to face each other in the Y-axis direction, and have a positional relationship in which the chuck table 10 moves in the X-axis direction between the cutting units 20a and 20b in plan view.

  The cutting device 1 has an X-axis moving device 8 (X-axis moving means) for moving the table base 10a of the chuck table 10 in the X-axis direction, and the X-axis moving device 8 is arranged below the bellows 10b. It is installed. The wafer W carried out from the wafer cassette on the cassette elevator 60 to the temporary placement mechanism 70 is placed on the chuck table 10 by a transfer device (not shown) and moved in the X-axis direction for cutting. The wafer W that has been subjected to the cutting process is cleaned and dried by the cleaning / drying means 80 and is then carried out again to the wafer cassette set in the cassette elevator 60.

  The wafer W processed by the cutting apparatus 1 is a wafer made of silicon, sapphire, gallium or the like as a base material, or a plate-like object such as glass, ceramics, a resin substrate, or metal. The wafer W is in a state in which the device-side surface on which a plurality of devices are formed and the back surface opposite to the device-side surface are attached to the dicing tape T, and the dicing tape T to which the wafer W is attached is attached to the annular frame F. Are accommodated in a wafer cassette (not shown).

  The upper surface 2a of the apparatus main body 2 of the cutting device 1 is configured with a water case 2b configured to be one step lower than the upper surface 2a. The water case portion 2b is configured to extend in the X-axis direction, and the chuck table 10 is configured to move within the water case portion 2b.

  The cutting water applied to the wafer W during the cutting process flows into a concave space formed by the water case portion 2b, and is discharged to the outside through a discharge port (not shown).

  Next, a method for detecting a cutting groove performed using the cutting apparatus 1 configured as described above will be described.

  First, as shown to FIG. 2 (A), the dicing tape sticking step which sticks the dicing tape T to the back surface Wb side of the wafer W used as a workpiece is implemented.

  As shown in FIG. 3, the dicing tape T includes an adhesive layer T1, a base material layer T2, and a reflective material layer T3 to which the back surface Wb of the wafer W is attached in order from the front side.

  The adhesive layer T1 and the base material layer T2 are configured to close the opening Fc of the annular frame F, and the adhesive layer T1 is attached to the back surface Fb side of the annular frame F.

  The adhesive layer T1 and the base material layer T2 can be transparent, translucent, milky white, black, etc., and transmit light.

  The reflective material layer T3 is disposed at least in a region where the wafer W is attached. In this embodiment, since the wafer W is circular, a circular reflecting material layer T3 having a diameter larger than the diameter of the wafer W is formed.

  The reflective material layer T3 can be composed of a material that reflects light. For example, the reflective material layer T3 is attached to the back surface T2b of the base material layer T2 or a back surface T2b. For example, it may be composed of a sheet-like aluminum foil.

  As shown in FIG. 2A, in the dicing tape adhering step, the adhesive layer T1 of the dicing tape T is adhered to the back surface Wb of the wafer W and the back surface Fb of the annular frame F so as to be covered from above. Thus, as shown in FIG. 2B, the wafer W is disposed above the adhesive layer T1, and the surface Wa of the wafer W is exposed.

  As shown in FIG. 2B, a reflective material layer T3 is disposed on the back side of the dicing tape T so as to surround a region where the wafer W is disposed on the dicing tape T.

  Next, after the dicing tape attaching step, a holding step for holding the wafer W on the chuck table 10 (FIG. 1) via the dicing tape T is performed.

  As shown in FIG. 4, the chuck table 10 has a suction holding portion 10c that communicates with the suction source 10d, and the wafer W is sucked and held via the dicing tape T on the upper surface of the suction holding portion 10c. It has become so.

  Next, as shown in FIG. 4, after the holding step, the first cutting blade 21 forms a first cutting groove M1 having a depth that does not reach the back surface Wb on the front surface Wa of the wafer W held on the chuck table 10. A first cutting step is performed.

  FIG. 5A is a cross-sectional view showing a state where the first cutting groove M1 having a depth not reaching the back surface Wb is formed on the front surface Wa of the wafer W. FIG. Here, the first cutting groove M <b> 1 is formed along the division planned line 13.

  Further, when a test metal pattern called a TEG (test element group) exists on the planned dividing line 13, the TEG is removed by cutting with the first cutting blade 21.

  As described above, the first cutting blade 21 performs the half cut to form the first cutting groove M1 having a depth that does not reach the back surface Wb of the wafer W, and the TEG is also removed during the formation. It becomes possible.

  Next, as shown in FIGS. 4 and 5B, after the first cutting step, the second cutting groove M2 extending from the bottom Ma of the first cutting groove M1 to the back surface Wb of the wafer W is changed to the first cutting groove M1. The 2nd cutting step formed with the 2nd cutting blade 22 whose blade thickness is thinner than the cutting blade 21 is implemented.

  FIG. 5B is a cross-sectional view showing a state in which the second cutting groove M2 reaching the back surface Wb of the wafer W is formed. Here, the second cutting groove M2 is formed by being cut into the bottom Ma of the first cutting groove M1, and is formed along the planned dividing line 13 in the same manner as the first cutting groove M1. Is.

  The second cutting groove M2 is completely cut into the wafer W and the adhesive layer T1, whereby the wafer W is fully cut. Moreover, it cuts into a part of base material layer T2.

  Next, as shown in FIG. 6, after the second cutting step, the first cutting groove M1 and the second cutting groove M2 are imaged from the surface Wa side while irradiating the light H1 from the surface Wa side of the wafer W. A detection step of detecting the edges E1, E2 of the cutting grooves M1, M2 is performed.

  In the present embodiment, as shown in FIG. 1, an imaging device 23 is attached to the cutting unit 20a, and the imaging device 23 is moved in the Y-axis direction together with the cutting unit 20a, and the chuck table 10 is moved in the X-axis direction. The desired position of the wafer W can be imaged.

  The imaging device 23 includes an illumination device 24 that illuminates an imaging target position, a microscope 25 that forms an image of the illuminated area, and an imaging element 26 such as a CCD.

  The illumination device 24 includes a light emitter such as an LED or a halogen lamp, and the light H <b> 1 is emitted from the illumination device 24 toward the wafer W.

  The microscope 25 includes an objective lens and a half mirror, and the half mirror and the illumination device 24 are connected by glass fiber. Above the half mirror, an image sensor 26 whose optical axis coincides with the microscope 25 is located. The image sensor 26 is connected to a monitor 27 and image processing means 28, and image information acquired by the image sensor 26 is transferred to the monitor 27 and image processing means 28, and is appropriately displayed and processed.

  In the detection step, as shown in FIGS. 6 and 7, the surface Wa of the wafer W illuminated by the irradiated light H1 is imaged to detect the edge E1 of the first cutting groove M1, and the irradiated light. H1 is reflected by the reflector layer T3 through the first cutting groove M1 and the second cutting groove M2, and the second cutting groove M2 illuminated from the back surface Wb side by the reflected light H2 is imaged from the front surface Wa side. Then, the edge E2 of the second cutting groove M2 is detected.

  Since the irradiated light H1 is reflected by the reflective material layer T3 due to the presence of the reflective material layer T3, the reflected light H2 (reflected light) is the first cutting groove as in the captured image 29 shown in FIG. An edge E2 that becomes a boundary portion between M1 and the second cutting groove M2 appears remarkably. In other words, the second cutting groove M2 does not become dark but becomes a bright region by the reflected light H2, and thereby, an edge E2 that becomes a boundary portion between the first cutting groove M1 and the second cutting groove M2 appears clearly. The captured image 29 can be acquired.

  Then, using the captured image 29, for example, the image processing unit 28 recognizes the difference in brightness between the first cutting groove M1 and the second cutting groove M2, and acquires the coordinates of the boundary portion of each region. By analyzing the image, the edges E1 and E2 can be automatically detected. The image analysis method for detecting the edges E1 and E2 is not particularly limited.

  Further, the center lines of the two edges E1 and the center lines of the two edges E2 are obtained, and if the center lines do not match, the center lines of the first cutting groove M1 and the second cutting groove M2 are obtained. Therefore, correction for matching the two is performed.

  This correction is performed by, for example, obtaining a deviation amount between the center line of the two edges E1 and the center line of the two edges E2, and using the deviation amount as a correction value, the first cutting blade 21 or the second This can be done by correcting the position of either one of the cutting blades 22 relative to the other.

The present invention can be implemented as described above.
That is, as shown in FIGS. 2 and 3, a dicing tape T is attached to a wafer W, which is a plate-like workpiece, and supports the wafer W, and includes an adhesive layer T1, a base material layer T2, and a reflector layer. The reflector layer T3 is disposed at least in a region where the wafer W is attached.

  Further, the reflecting material layer T3 of the dicing tape T is made of a paint or a sheet-like member.

  And using the above dicing tape T, after the dicing tape sticking step which sticks the dicing tape T on the back surface Wb side of the wafer W which becomes a workpiece, and after the dicing tape sticking step, the dicing tape T is passed through. A holding step for holding the wafer W on the chuck table 10 (FIG. 1), and a first cutting groove M1 having a depth that does not reach the back surface Wb on the front surface Wa of the wafer W held on the chuck table 10 after the holding step. Are formed by the first cutting blade 21, and after the first cutting step, the second cutting groove M2 extending from the bottom Ma of the first cutting groove M1 to the back surface Wb of the wafer W is formed in the first cutting step. A second cutting step formed by a second cutting blade 22 having a thinner blade thickness than the cutting blade 21 and the surface of the wafer W after the second cutting step. a step of detecting the edges E1, E2 of the cutting grooves M1, M2 by imaging the first cutting groove M1 and the second cutting groove M2 from the surface Wa side while irradiating the light H1 from the a side, In the detection step, as shown in FIGS. 6 and 7, the surface Wa of the wafer W illuminated by the irradiated light H1 is imaged to detect the edge E1 of the first cutting groove M1, and the irradiated light H1 is detected. The second cutting groove M2 reflected from the reflective material layer T3 through the first cutting groove M1 and the second cutting groove M2 and illuminated from the back surface Wb side by the reflected light H2 is imaged from the front surface Wa side. The edge E2 of the second cutting groove M2 is detected.

  According to this detection method, by using the dicing tape T provided with the reflective material layer T3, the second cutting groove M2 can be illuminated with the light H2 reflected from the back surface Wb side. , M2 edges E1 and E2 can be detected.

  Further, unlike the prior art, it is not necessary to cut a detection groove that is used only for positioning of the cutting blade, and clogging of the cutting blade can be suppressed.

  In addition to the embodiment described above, as shown in FIG. 5A, the reflective material layer T3 may be provided between the adhesive layer T1 and the base material layer T2. In this case, when the second cutting groove M2 is formed, the light is reflected by the reflective material layer T3. Therefore, the light is not cut into the reflective material layer T3, and only the adhesive layer T1 is cut into a full cut. To do. Moreover, since the adhesive layer T1 is closer to the workpiece than the reflector layer T3, it may be made of a material that does not transmit light.

DESCRIPTION OF SYMBOLS 1 Cutting device 10 Chuck table 13 Scheduled division line 21 Cutting blade 22 Cutting blade 23 Imaging device 24 Illumination device 29 Imaged image E1 Edge E2 Edge H1 Light H2 Light M1 Cutting groove M2 Cutting groove T Dicing tape T1 Adhesive layer T2 Base material layer T3 Reflector layer W wafer

Claims (1)

A method for detecting a cutting groove,
On the back side of the plate-like workpiece, an adhesive layer, a base material layer, and a reflector layer are formed, and the reflector layer is a dicing tape disposed at least in a region where the workpiece is adhered. A dicing tape sticking step to stick,
After the dicing tape attaching step, a holding step for holding the workpiece on the chuck table via the dicing tape;
After the holding step, a first cutting step of forming a first cutting groove having a depth that does not reach the back surface on the surface of the workpiece held on the chuck table with a first cutting blade;
After the first cutting step, the second cutting groove from the bottom of the first cutting groove to the back surface of the workpiece is formed with a second cutting blade having a thinner blade thickness than the first cutting blade. A second cutting step to form;
After the second cutting step, imaging the first cutting groove and the second cutting groove from the surface side while irradiating light from the surface side of the workpiece, the first and second cutting A detection step of detecting an edge of the groove,
In the detection step,
The edge of the first cutting groove is detected by imaging the surface of the workpiece illuminated by the irradiated light,
The irradiated light is reflected by the reflector layer through the first cutting groove and the second cutting groove, and the second cutting groove illuminated from the back side by the reflected light is reflected on the surface side. From the image, the edge of the second cutting groove is detected,
A method for detecting a cutting groove.

Images