JP6004761B2 - Dicing method - Google Patents

Description

  The present invention relates to a dicing method for dicing a workpiece having a plurality of dicing lines formed on the front surface from the back surface.

  In the semiconductor device manufacturing process, a plurality of areas are defined by dicing lines called streets formed in a lattice shape on the surface of a semiconductor wafer such as a silicon wafer or a gallium arsenide wafer having a substantially disk shape. Then, a device such as an IC or LSI is formed.

  Such a semiconductor wafer is ground into a predetermined thickness after the back surface is ground by a grinding device, and then divided into individual devices by a cutting device or a laser processing device. The divided devices are various electric machines such as mobile phones and personal computers. Widely used in equipment.

  Dicing with a cutting device is usually performed from the front side of a workpiece such as a wafer, but laser processing or cutting may be performed from the back side to prevent debris or cutting debris from adhering to the device. .

  Further, in order to improve the brightness of a semiconductor wafer or optical device wafer in which a TEG (Test Element Group) made of metal is formed on a street (dicing planned line), the wafer is irradiated with a laser beam from the back side. A method is also employed in which a modified layer is formed inside, and then an external force is applied to the wafer to divide the modified layer into individual chips from the division starting point.

  When dicing from the back surface of the workpiece, for example, an infrared camera (IR camera) as disclosed in Japanese Patent Application Laid-Open No. 7-075955 is used to detect a dicing scheduled line formed on the front surface. Thus, a method is widely used in which a workpiece is imaged from the back surface side and a dicing scheduled line on the front surface side is detected.

JP 7-075955 A

  However, in order to image the dicing line on the surface from the back side of the workpiece with the IR camera, the thickness of the workpiece must be sufficiently thin, and depending on the type and state of the surface pattern and the flatness of the back surface However, it is difficult to obtain a clear image, and it is difficult to perform dicing along a dicing planned line from the back side.

  The present invention has been made in view of such points, and the object is to dice from the back side regardless of the type and state of the surface pattern, the flatness of the back side, the thickness of the workpiece, etc. To provide a dicing method that enables dicing along a line.

According to the present invention, there is provided a dicing method for dicing a workpiece having a plurality of scheduled dicing lines on the surface and having a notch on the outer periphery from the back surface, and imaging the workpiece from the surface to form a captured image. After performing the imaging step, the dicing scheduled line position storing step that detects the position of the dicing planned line from the outer notch portion based on the captured image, and stores it in the storage means, and the dicing scheduled line position storing step A holding step for holding the front side of the workpiece with a chuck table and exposing the back side, and after performing the holding step, imaging the back side of the workpiece held on the chuck table and taking the notch A detection step for detecting a portion, and after performing the detection step, the captured image formed in the imaging step is used as a reference for the cutout portion. Based on the notched portion of the workpiece detected in the detection step and the planned dicing line position stored in the dicing planned line position storing step, a reversed image formed by inverting the left and right is formed and displayed on the display means. And a dicing step for dicing a workpiece from the back surface and displaying a dicing scheduled line during dicing on the reverse image in real time .

  According to the dicing method of the present invention, the workpiece is imaged from the surface, the position of the dicing planned line from the outer notch is detected and stored, and the back side of the workpiece is imaged during dicing. Then, the notched portion is sharpened, and the workpiece is diced based on the notched portion and the stored planned dicing line position, and the dicing planned line being diced is displayed on the reverse image. Therefore, dicing along the planned dicing line can be reliably performed from the back surface side of the workpiece regardless of the type and state of the surface pattern, the flatness of the back surface, the thickness of the workpiece, and the like.

It is a perspective view of the dicing apparatus (cutting apparatus) suitable for implementing the dicing method of this invention. It is a side view which shows an imaging step. It is a top view of the semiconductor wafer explaining the dicing plan line position storage step. It is a partial cross section side view which shows a holding | maintenance step. It is a partial cross section side view which shows a detection step. It is a partial cross section side view which shows a dicing step.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Referring to FIG. 1, a perspective view of a dicing apparatus (cutting apparatus) 2 suitable for carrying out the dicing method of the present invention is shown.

  On the front side of the dicing apparatus 2, an operation panel 4 is provided for an operator to input instructions to the apparatus such as machining conditions. In the upper part of the apparatus, a display monitor 6 such as a CRT on which a guidance screen for an operator and an image captured by an imaging unit described later are displayed is provided.

  A plurality of semiconductor wafers 11 (hereinafter sometimes simply referred to as wafers) 11 to be diced by the dicing apparatus 2 are attached to a dicing tape T mounted on an annular frame F, and then stored in a wafer cassette 8. The 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 unit 10 is provided for unloading the wafer 11 from the wafer cassette 8 and loading the wafer after cutting into the wafer cassette 8.

  Between the wafer cassette 8 and the carry-in / out unit 10, a temporary placement area 12, which is an area on which the wafer 11 to be carried in / out, is temporarily placed, is provided. An alignment mechanism 14 is provided for aligning the position at a certain position.

  A transport unit 16 having a swivel arm that sucks and transports the wafer 11 is disposed in the vicinity of the temporary placement area 12, and the wafer 11 that has been transported to the temporary placement area 12 and aligned is transported by the transport unit 16. Is sucked and conveyed onto the chuck table 18 and sucked and held by the chuck table 18.

  The chuck table 18 is configured to be rotatable and reciprocally movable in the X-axis direction by a machining feed mechanism (not shown). An area to be cut of the wafer 11 is formed above the movement path of the chuck table 18 in the X-axis direction. An alignment unit 22 for detection is provided. Reference numeral 20 denotes a clamp for clamping the annular frame F.

  The alignment unit 22 includes an imaging unit 24 having a microscope and a CCD camera for imaging the surface of the wafer 11, and can detect a region to be cut by processing such as pattern matching based on an image acquired by imaging. . The image acquired by the imaging unit 24 is displayed on the display monitor 6.

  On the left side of the alignment unit 22, a cutting unit 26 for cutting the wafer 11 held on the chuck table 18 is disposed. The cutting unit 26 is configured integrally with the alignment unit 22, and both move together in the Y-axis direction and the Z-axis direction.

  The cutting unit 26 is configured by mounting a cutting blade 30 having a cutting edge on the outer periphery of the end of a rotatable spindle 28 and is movable in the Y-axis direction and the Z-axis direction. The cutting blade 30 is located on the extended line of the imaging unit 24 in the X-axis direction. The movement of the cutting unit 26 in the Y-axis direction is achieved by an index feed mechanism (not shown).

  Reference numeral 34 denotes a spinner cleaning unit that cleans the wafer 11 that has been subjected to the cutting process. The wafer 11 that has been subjected to the cutting process is transported to the spinner cleaning unit 34 by the transport unit 32, and is subjected to spin cleaning and spin drying by the spinner cleaning unit 34. .

  Next, the dicing method of the present invention will be described in detail with reference to FIGS. In the dicing method of the present invention, as shown in FIG. 2, an imaging step is performed in which the imaging unit 38 forms an imaged image by imaging the surface 11 a of the wafer 11 placed on the table 36 with the imaging unit 38.

  The imaging unit 38 includes a microscope and a CCD camera. The surface 11a of the wafer 11 is magnified by the microscope and imaged by the CCD camera. The imaging unit 38 is connected to the personal computer 40, and a captured image is displayed on a screen (screen) 42 of the personal computer 40.

  Next, based on the captured image, a dicing planned line position is detected from the notch on the outer periphery of the wafer 11 and the dicing planned line position is stored in the memory of the personal computer. Then, the dicing scheduled line position information stored in the memory of the personal computer is sent to the controller of the dicing apparatus 2 and stored in the memory of the controller.

  The dicing scheduled line position storing step will be described in detail with reference to FIG. FIG. 3A shows the case of the wafer 11 in which the outer notch is formed with the notch 17, and FIG. 3B shows the case of the wafer 11 in which the orientation flat 21 is formed as the outer notch. .

  First, with reference to FIG. 3A, an example of a dicing scheduled line position storing step for the wafer 11 in which the notch is formed from the notch 17 will be described. For the planned dicing line 13 extending in the first direction, the planned dicing line 13a closest to the notch 17 is detected, and the distance y1 between the apex 17a of the notch 17 and the planned dicing line 13a is set as the planned dicing line position. Store it in the PC memory.

  On the other hand, the dicing planned line 13 extending in the second direction is between the extension line 19 of the apex 17a of the notch 17 and the dicing planned line 13b at the end of the dicing planned line 13 extending in the second direction. The distance y2 is detected, and y2 is stored as a dicing scheduled line position in the memory of the personal computer.

  Then, the distances y1 and y2 stored in the memory are sent to the controller of the dicing apparatus 2 as dicing scheduled line positions and stored in the memory of the controller. Note that the extension line 19 of the apex 17 a of the notch 17 does not necessarily coincide with the dicing scheduled line 13.

  Next, with reference to FIG. 3B, a dicing scheduled line position storing step in the case where the orientation flat 21 is formed as a notch will be described. In the wafer 11 on which the orientation flat 21 is formed, the planned dicing line 13 extending in the first direction is formed in parallel with the orientation flat 21.

  Therefore, in the position storing step of the dicing planned line 13 extending in the first direction, the distance y3 between the dicing planned line 13a closest to the orientation flat 21 and the orientation flat 21 is detected, and this distance y3 is planned to be diced. The line position is stored in the personal computer memory.

  For detecting the position of the planned dicing line 13 extending in the second direction, the distance y4 between the end 21a of the orientation flat 21 and the end of the dicing planned line 13b closest to the end 21b is detected. This distance y4 is stored in the memory of the personal computer as the dicing scheduled line position.

  Then, the dicing scheduled line positions y3 and y4 stored in the memory are sent to the controller of the dicing apparatus 2, and the dicing scheduled line positions y3 and y4 are stored in the controller.

  In the above description, the distances y1 to y4 to each of the dicing scheduled lines 13 extending in the first direction and the second direction are detected and stored in the memory of the personal computer. Thereafter, the data is stored in the controller of the dicing device 2, but the distances of all lines from the reference point may be detected and stored in the controller of the dicing device 2.

  By storing the position information of all the dicing planned lines 13, the dicing on the dicing planned lines 13 can be surely diced even in the case of a wafer having poor pattern accuracy and varying index amounts. it can.

  In the embodiment for detecting the distance from the reference point described above with reference to FIGS. 3A and 3B to one dicing line in each direction, the distance between the dicing lines 13 from the design data of the wafer 11 is determined. Therefore, the distance is stored as an index amount in the memory of the controller of the dicing apparatus 2.

  In the embodiment described above, the personal computer 40 is connected to the controller of the dicing apparatus, the dicing scheduled line position stored in the personal computer 40 is sent to the controller of the dicing apparatus 2, and the planned dicing line position is stored in the controller. Instead of connecting to the dicing apparatus 2, the detected dicing scheduled line position information may be converted into a bar code, and the bar code may be attached to the annular frame F that supports the wafer 11.

  In this case, when the wafer 11 is diced, the barcode information is read by the barcode reader, and the dicing scheduled line position is stored in the controller of the dicing apparatus 2.

  After performing the dicing planned line position storing step, as shown in FIG. 4, the holding step of sucking and holding the front surface 11a side of the wafer 11 with the chuck table 18 of the dicing apparatus 2 and exposing the back surface 11b is performed. In this holding step, the annular frame F is clamped and fixed by the clamp 20.

  After the wafer 11 is held by the chuck table 18, as shown in FIG. 5, a detection step is performed in which the back surface 11 b side of the wafer 11 is imaged by the imaging unit 24 of the dicing apparatus 2 and the notch 17 or the orientation flat 21 is detected. .

  After performing the detection step, the captured image formed in the imaging step is inverted 180 degrees with respect to the notch 17 or the orientation flat 21, that is, the left and right are inverted, and the inverted image 25 is displayed on the screen 6 a of the monitor 6.

  When the notch is the notch 17 shown in FIG. 3A, an image obtained by inverting the left and right with reference to the extension line 19 of the apex 17a of the notch 17 is displayed on the screen 6a of the monitor 6 as an inverted image 25. .

  On the other hand, when the cut-out portion is the orientation flat 21 shown in FIG. 3B, the left and right sides of the wafer 11 are reversed with respect to the vertical bisector of the orientation flat 21, and the reversed image 25 is displayed on the screen 6a of the monitor 6. Display above.

  Then, as shown in FIG. 6, based on the notch portion (notch 17 or orientation flat 21) of the wafer 11 detected in the detection step and the position y1 or y3 of the planned dicing line stored in the planned dicing line position storing step. Then, the cutting blade 30 is cut in the dicing scheduled line 13a of the wafer 11 while rotating at high speed in the direction of arrow A, and the wafer 11 is diced while the chuck table 18 is processed and fed in the direction of arrow X1.

  During this dicing, as indicated by an arrow B on the screen 6a of the display monitor 6, the groove 27 being diced is displayed on the reverse image 25 displayed on the display monitor 6 so as to expand in real time. Thus, the operator can confirm on the display monitor 6 which line is currently being diced.

  While the cutting unit 26 is indexed in the Y-axis direction, all the dicing scheduled lines 13 extending in the first direction are diced. Next, after the chuck table 18 is rotated by 90 degrees, the dicing planned line position y2 is first diced on the dicing planned line 13b based on y4, and then the chuck table 18 is indexed in the Y-axis direction in the second direction. All the dicing scheduled lines 13 extending in the step are diced.

  Dicing by the cutting blade 30 includes full cut and half cut. Further, in addition to dicing by the dicing apparatus 2, dicing may be performed by a laser processing apparatus.

  In dicing by a laser processing apparatus, a modified layer is formed inside the wafer by ablation processing using a laser beam having a wavelength that is absorptive to the wafer 11 and using a laser beam having a wavelength that is transmissive to the wafer 11. Including a processing method to be formed.

  In the above-described embodiment, the example in which the dicing method of the present invention is applied to the semiconductor wafer 11 has been described. However, the workpiece is not limited to the semiconductor wafer 11, and a dicing scheduled line is formed on the surface of the optical device wafer or the like. Other set workpieces are also included.

2 Dicing device 6 Display monitor 11 Semiconductor wafer 13 Dicing schedule line 15 Device 17 Notch 18 Chuck table 21 Orientation flat 24, 38 Imaging unit 26 Cutting unit 30 Cutting blade 25 Reverse image 40 Personal computer

Claims (2)

A dicing method for dicing a workpiece having a plurality of dicing lines formed on the front surface and having a notch on the outer periphery from the back surface,
An imaging step of imaging the workpiece from the surface to form a captured image;
A dicing planned line position storing step of detecting a position of a dicing planned line from the outer notch portion based on the captured image and storing it in a storage means;
After performing the dicing scheduled line position storing step, a holding step of holding the front side of the workpiece with a chuck table and exposing the back side;
After performing the holding step, a detection step of imaging the back side of the workpiece held on the chuck table and detecting the notch,
After performing the detection step, the captured image formed in the imaging step is formed on the display means by forming a reversed image obtained by inverting the left and right with respect to the notch, and the workpiece detected in the detection step Based on the notch of the object and the planned dicing line position stored in the planned dicing line position storing step, the workpiece is diced from the back side and the dicing planned line being diced is displayed in real time on the inverted image. Dicing step to
A dicing method comprising:   2. The dicing method according to claim 1, wherein in the dicing scheduled line position storing step, all dicing scheduled line positions on the workpiece from the cutout portion of the workpiece are stored.

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