JP2017216274A - Processing method for wafer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To divide a wafer while leaving a wafer ID and an outer peripheral excessive region.SOLUTION: A wafer (W) has: a device region (W1), and an outer peripheral margin region (W2) surrounding the device region and having therein an ID display part (C) including a wafer ID. First, a separation groove (W4) is formed, which separates the device region and the outer peripheral margin region. Then, after grinding tape (T) is attached to the surface (Wa) side of the wafer, the wafer is ground from the rear side (Wb) of the wafer up to a finish thickness by using a grinding wheel (25). By grinding this, the separation groove is exposed from the rear surface side of the wafer, and the wafer is divided into the device region and the outer peripheral margin region. Thereafter, using a cutting blade (32), a cut is made between the ring-shaped end material (W2a) of the outer peripheral margin region and the device region, and feed for cutting is carried out. The cutting blade is raised between the ring-shaped end material and the device region, and the device region of the wafer is divided.SELECTED DRAWING: Figure 8

Description

  The present invention relates to a wafer processing method in which a wafer ID is formed in an outer peripheral surplus region surrounding a device region.

  In the semiconductor device manufacturing process, a plurality of regions are partitioned by dividing lines called streets formed in a lattice pattern on the surface of a substantially disk-shaped semiconductor wafer, and devices such as ICs and LSIs are placed in each partitioned region. Form.

  A semiconductor wafer is ground to a predetermined thickness by grinding the backside with a grinding machine, and then divided into individual devices by a cutting machine or a laser machining apparatus. The divided devices are widely used in various electronic devices such as mobile phones and personal computers. It's being used. Before grinding the back surface of the semiconductor wafer, a protective tape is attached to the surface of the semiconductor wafer in order to protect the devices formed on the surface of the semiconductor wafer. A semiconductor wafer is sucked and held through a protective tape by a chuck table of a grinding apparatus, and the back surface of the semiconductor wafer is ground.

JP 2006-303051 A

  Before the grinding as described above, the outer peripheral surplus area surrounding the device area may be cut first and removed depending on the grinding conditions and the like. However, in this case, there is a problem in that the ID printed in the outer peripheral surplus area is not removed, and the information of each device associated with the ID cannot be processed in the subsequent process. Further, when the outer peripheral surplus area is removed before grinding, the outer diameter of the semiconductor wafer changes, and therefore, the transfer pad for transferring the semiconductor wafer cannot be used with a specification corresponding to the outer diameter of the standard semiconductor wafer. For this reason, it is necessary to use equipment having a plurality of transfer pads according to the wafer whose outer diameter changes, and there is a problem that equipment cost increases.

  The present invention has been made in view of the above points, and an object of the present invention is to provide a wafer processing method capable of dividing a wafer while leaving a wafer ID and an outer peripheral surplus region.

  In the wafer processing method of the present invention, the back surface side of a wafer having a device region having a device and a line to be divided on the surface and an outer peripheral surplus region surrounding the device region and having a wafer ID formed is thinned to a finished thickness and divided. A wafer processing method for processing along a planned line, wherein the device region and the outer peripheral surplus region are divided along the boundary between the device region and the outer peripheral surplus region at least halfway along the thickness direction of the wafer to the finished thickness. After performing the dividing groove forming step for forming the dividing groove and the dividing groove forming step, the grinding tape adhering step for adhering the grinding tape to the front surface side of the wafer, and the grinding tape adhering step are performed, and then the grinding tape Grinding step where the side is held on the chuck table and ground to the finished thickness with the grinding wheel from the back side of the wafer. And after performing the grinding step, the transfer step for attaching the cutting tape to the ground surface of the wafer after grinding and peeling the grinding tape for transfer, and the device region and the outer peripheral surplus region of the wafer attached to the cutting tape. The ring-shaped end material is placed on the chuck table of the cutting device, the cutting blade is cut halfway along the cutting tape between the ring-shaped end material in the outer peripheral surplus region and the device region, and the cutting feed is performed. And a splitting step for dividing the device region of the wafer along the planned split line formed on the surface and rising between the end material and the device region, and a ring-shaped end material of the outer peripheral surplus region in a later process It is characterized in that it is identified by the wafer ID formed in (1).

  According to this configuration, even if the dividing groove is formed on the wafer, the outer peripheral surplus region remains in a ring shape after grinding and division, and the wafer ID also remains, so processing based on the wafer ID in the subsequent process after the division step is a problem. Can be done without. In addition, since the outer peripheral surplus region remains on the chuck table even after the grinding step and the dividing step, the outer diameter of the wafer does not change before and after the grinding or dividing. As a result, it is only necessary to prepare one type of wafer transfer pad with a specification corresponding to the outer diameter of a standard wafer, and an increase in equipment cost can be suppressed. Here, in the present invention, when the dividing step is performed, the outer peripheral surplus region is formed as a ring-shaped end material, and both end portions of the cutting groove that is linear are positioned between the ring-shaped end material and the device region. Thereby, even if a device area | region is cut in a division | segmentation step, a ring-shaped end material will be parted and it will not be separated into pieces, but the state which continued in series can be maintained. As a result, the ring-shaped end material does not scatter and become a fine chip, so that the quality of the device can be prevented from being lowered and the wafer ID can be left in a good state.

  According to the present invention, it is possible to divide the wafer while leaving the wafer ID and the outer peripheral surplus area.

It is a schematic sectional drawing of the wafer which concerns on this Embodiment. It is a figure which shows an example of the dividing groove formation step which concerns on this Embodiment. It is a figure which shows an example of the grinding tape sticking step which concerns on this Embodiment. It is a figure which shows an example of the grinding step which concerns on this Embodiment. It is a figure which shows an example of the grinding step which concerns on this Embodiment. It is a figure which shows an example of the transfer step which concerns on this Embodiment. It is a figure which shows an example of the division | segmentation step which concerns on this Embodiment. It is a figure which shows an example of the division | segmentation step which concerns on this Embodiment.

  Hereinafter, a wafer processing method according to the present embodiment will be described in detail with reference to the accompanying drawings. FIG. 1 is a schematic sectional view of a wafer according to the present embodiment. FIG. 2 is a diagram showing an example of the dividing groove forming step according to the present embodiment. FIG. 3 is a diagram illustrating an example of the grinding tape attaching step according to the present embodiment. 4 and 5 are diagrams showing an example of a grinding step according to the present embodiment. FIG. 6 is a diagram illustrating an example of a transfer step according to the present embodiment. 7 and 8 are diagrams illustrating an example of the division step according to the present embodiment.

  As shown in FIG. 1, the wafer W is formed in a substantially disc shape, and a plurality of devices D are formed in a convex shape in the center so as to protrude from the surface Wa. The wafer W has a device region W1 in which a plurality of devices D are formed, and an outer peripheral surplus region W2 that surrounds the device region W1. The device region W1 and the outer peripheral surplus region W2 have different upper surface height positions in FIG. 1, and there are steps at their boundaries W3. The device region W1 is partitioned into a plurality of regions by the planned division lines L (see FIG. 8) arranged in a lattice pattern, and the device D is formed in the partitioned region. An ID display portion C for specifying the wafer ID is formed in the outer peripheral surplus region W2. In the ID display unit C, a predetermined symbol, barcode, or the like is applied to the surface Wa side by printing or labeling, and is associated with information such as the type of device on the wafer W and the position of a defective device. Note that the device D is not formed on the back surface Wb opposite to the front surface Wa of the wafer W. The wafer W may be a semiconductor wafer such as silicon or gallium arsenide as long as the device D is formed on the surface Wa, or may be a ceramic, glass, or sapphire optical device wafer.

  As shown in FIG. 2, a dividing groove forming step is first performed. In the dividing groove forming step, the cutting means 10 is used to form the dividing groove W4 at the boundary W3 on the surface Wa of the wafer W held on the chuck table 11. The chuck table 11 holds the wafer W with the upper surface serving as a holding surface, and can rotate around the rotation shaft 12. The cutting means 10 includes a cutting blade 15 attached to the tip of a spindle (not shown), and can rotate the cutting blade 15 at a predetermined rotational speed.

  In the dividing groove forming step, first, the back surface Wb side of the wafer W is placed on the chuck table 11 to expose the front surface Wa upward. Thereafter, the wafer W is sucked and held by the chuck table 11 by operating a suction source (not shown). Then, while rotating the cutting blade 15 of the cutting means 10, the cutting blade 15 is lowered in a direction approaching the boundary W <b> 3 of the wafer W, and the cutting edge of the cutting blade 15 is cut into the surface Wa of the wafer W. Subsequently, when the chuck table 11 rotates at least once around the axis of the rotary shaft 12, the cutting blade 15 cuts around the center of the wafer W along the boundary W3, and the device region W1 and the outer peripheral surplus region W2 A ring-shaped dividing groove W4 is formed. Here, the dividing groove W4 is formed at a groove depth d at least halfway in the thickness direction so as not to penetrate to the back surface Wb, and the groove depth d is obtained when the wafer W is ground to a finished thickness in a grinding step described later. It is set at least so as to be exposed on the back surface Wb, and is preferably set to about 2/3 of the total thickness of the wafer W.

  The dividing groove forming step may be performed by ablation processing using a laser beam in addition to the cutting means 10 as described above. Specifically, a laser beam having a wavelength having an absorptivity with respect to the wafer W is irradiated in a ring shape from the surface Wa side of the wafer W to the boundary W3 to form the dividing groove W4.

  As shown in FIG. 3, a grinding tape sticking step is performed after the dividing groove forming step. In the grinding tape attaching step, the grinding tape T is attached to the surface Wa of the wafer W. For example, the sticking roller rolls on the grinding tape T while feeding the grinding tape T from the outer peripheral edge side of the wafer W to the surface Wa of the wafer W, and the grinding tape T is applied to the entire surface Wa of the wafer W. Affix. As described above, since there is a step at the boundary W3 between the device region W1 and the outer peripheral surplus region W2, a step is also formed at a position corresponding to the boundary W3 of the grinding tape T. The grinding tape T is not particularly limited, and a grinding tape having an adhesive layer on the side in contact with the surface Wa of the wafer W is used.

  As shown in FIGS. 4 and 5, a grinding step is performed after the grinding tape attaching step. In the grinding step, the wafer W is ground from the back surface Wb side to the finished thickness by grinding the wafer W held on the chuck table 21 using the grinding means 20. The chuck table 21 holds the wafer W with the upper surface as a holding surface, and can rotate around the rotation shaft 22. The grinding means 20 includes a spindle 24 having a vertical axis, a grinding wheel 25 attached to the lower end of the spindle 24, and a grinding wheel 26 fixed in an annular shape to the lower part of the grinding wheel 25. The grinding means 20 can rotate the grinding wheel 25 at a predetermined rotational speed by rotating the spindle 24 with a motor (not shown).

  In the grinding step, first, as shown in FIG. 4, the grinding tape T side is placed on the chuck table 21 to expose the back surface Wb of the wafer W upward. Thereafter, the wafer W is sucked and held by the chuck table 21 via the grinding tape T by the operation of a suction source (not shown), and the chuck table 21 is rotated around the rotation shaft 22. Subsequently, while rotating the grinding wheel 25 of the grinding means 20, the grinding means 20 is lowered in a direction approaching the back surface Wb of the wafer W, and the rotating grinding wheel 26 is brought into contact with the back surface Wb. Then, as shown in FIG. 5, by grinding to the depth reaching the dividing groove W4 while pressing the back surface Wb of the wafer W with the grinding wheel 26, the dividing groove W4 is exposed from the back surface Wb, and the dividing groove W4 is bordered. As a result, the device region W1 and the outer peripheral surplus region W2 are separated. After these are separated, grinding by the grinding wheel 26 is continued until the wafer W is thinned to the finished thickness.

  Here, in the grinding step, the grinding tape T adhered to the outer peripheral surplus region W2 by the step of the grinding tape T in the state of FIG. 4 before the back surface Wb of the wafer W reaches the dividing groove W4 is applied to the chuck table 21. The suction holding force becomes weaker away from the upper surface. However, in the state of FIG. 4, the grinding tape T adhered to the device region W1 receives a suction force from the chuck table 21 over a wide area, so that the state in which the wafer W is satisfactorily held is maintained. When the grinding progresses from the state of FIG. 4 and the device region W1 and the outer peripheral surplus region W2 are separated from each other with the dividing groove W4 as a boundary, the outer peripheral surplus region W2 falls as a ring-shaped end material W2a as shown in FIG. To do. As a result, the grinding tape T adhered to the outer peripheral surplus area W2 comes into contact with the upper surface of the chuck table 21, and the ring-shaped end material W2a of the outer peripheral surplus area W2 of the wafer W is not reduced so that the suction force by the chuck table 21 is not reduced. Is retained.

  Thus, in the grinding step according to the present embodiment, the device region W1 and the outer peripheral surplus region W2 are separated from each other with the dividing groove W4 as a boundary. And since the grinding tape T stuck to the outer peripheral surplus area W2 is brought into contact with the upper surface of the chuck table 21 and held by suction, fluttering of the outer peripheral surplus area W2 can be suppressed, and cracks in the outer peripheral surplus area W2 caused by the fluttering. Can be prevented.

  As shown in FIG. 6, a transfer step is performed after the grinding tape attaching step. In the transfer step, the wafer W is placed inside the annular frame F, and then the cutting tape Tp is unwound and attached to the back surface Wb and the frame F of the wafer W. Thereby, the device area W1 of the wafer W and the ring-shaped end material W2a of the outer peripheral surplus area W2 are supported inside the frame F via the cutting tape Tp. In this sticking, for example, the sticking roller is rolled on the cutting tape Tp, and the cutting tape Tp is stuck to the entire back surface Wb serving as the grinding surface of the wafer W and one surface of the frame F. After the cutting tape Tp is attached, the grinding tape T attached to the surface Wa of the wafer W is peeled off, whereby the transfer of the wafer W from the grinding tape T to the cutting tape Tp is completed.

  As shown in FIGS. 7 and 8, a dividing step is performed after the transfer step. In the dividing step, first, ring-shaped end materials of the frame F, the device region W1 of the wafer W, and the outer peripheral surplus region W2 on the chuck table 31 (not shown in FIG. 8) of the cutting apparatus 30. W2a is placed and held by suction or the like. Thereafter, the cutting blade 32 is positioned above the planned division line L and between the ring-shaped end material W2a and the device region W1. After this positioning, the cutting blade 32 descends while rotating at high speed, and the cutting blade 32 cuts from the surface Wa of the wafer W through the entire thickness direction of the wafer W to the middle of the cutting tape Tp in the thickness direction. Then, the cutting blade 32 in the cut state and the wafer W on the chuck table 31 are relatively moved so as to cut and feed along the planned division line L via a feed mechanism (not shown), and along the planned division line L. The wafer W is cut to form a cutting groove W5. When the cutting groove W5 is formed by such cutting feed and the cutting blade 32 reaches between the ring-shaped end material W2a and the device region W1, the cutting blade 32 is raised therebetween. Therefore, the start point W5a and the end point W5b, which are the end portions of the cutting groove W5, are located within the width of the ring-shaped end material W2a and do not divide the ring-shaped end material W2a across the width direction.

  In the formation of the cutting groove W5, the lowering speed of the cutting blade 32 when forming the start point W5a side is a low speed for reasons such as mitigating the impact on the wafer W. On the other hand, the rising speed of the cutting blade 32 after forming the end point W5b side is free from restrictions such as impact relaxation, so that the machining time can be shortened by setting it higher than the lowering speed.

  By repeating the same procedure as described above, the cutting groove W5 is formed along all the division lines L formed on the surface Wa of the wafer W, and the device region W1 is divided into individual devices D. The step is complete. Even in the process after the division step is completed, the ring-shaped end material W2a is not divided, and the ring-shaped state around the device region W1 can be maintained. Thereby, ID display part C formed in ring shape end material W2a can be identified via detection means, such as a camera and a sensor.

  As described above, according to the processing method according to the present embodiment, even if the dividing groove W4 is formed, the wafer W is processed from before the grinding step (see FIG. 4) to after the dividing step (see FIGS. 7 and 8). It is possible to maintain the state where the outer peripheral surplus region W2 is formed. Thereby, even if the device D has a convex shape, the outer peripheral surplus area W2 and the ID display part C are left until after the division step while preventing the occurrence of cracks in the outer peripheral surplus area W2 due to flapping during grinding. Can do. As a result, various processes based on information obtained by identifying the ID display unit C after the division step can be performed. In addition, since the outer peripheral surplus area W2 remains, the outer diameter of the wafer W can be maintained so as not to change, and the existing wafer W transfer mechanism can be used as one type without change. Thereby, it is not necessary to use a plurality of transfer mechanisms in accordance with the change in the outer diameter of the wafer W, and an increase in equipment cost for the transfer mechanism can be suppressed and economical.

  Furthermore, since the start point W5a and the end point W5b of the cutting groove W5 formed in the division step are located within the width of the ring-shaped end material W2a, uncut regions are formed on the start side and the end side of the cutting feed. Is done. Therefore, even if the cutting grooves W5 are formed in all the division lines L, the ring-shaped end material W2a can be kept in a ring shape. As a result, the ring-shaped end material W2a is prevented from being scattered as a fine chip, so that it is possible to prevent cutting defects and the like due to the scattering of the chip, and to contribute to good remaining of the ID display portion C.

  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, direction, 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, in the above embodiment, the device D has a convex shape and is formed on the surface Wa of the wafer W. However, a wafer having no convex portion may be processed. Here, in a wafer whose chamfering process has been applied to the outer periphery to prevent cracking and dust generation, the outer periphery of the wafer chamfered by grinding becomes a knife edge shape and is easily chipped. It may be removed from the outer periphery of the wafer by trimming in advance. In this case, there is a problem that the ID display part C for specifying the wafer ID by the trimming process is lost. Even with such a wafer, the grinding method T and the cutting tape Tp are adhered to the outer peripheral surplus region W2 when the grinding and dividing are performed without performing the trimming process in the processing method of the above embodiment. The ID display portion C can be left while preventing the outer periphery of the wafer from being chipped.

  Further, in the dividing step, the two cutting blades 32 may be used, and the processing may be performed by a so-called dual cut method in which cutting is performed on different division lines L of the wafer W at the same time. If the machining is performed by dual cutting, the machining time can be shortened even in the slow-in machining in which the lowering speed of the cutting blade 32 when the start point W5a side of the cutting groove W5 is formed is slow.

  As described above, the present invention has an effect that the wafer can be divided while leaving the wafer ID and the peripheral surplus area, and processing of the wafer in which the wafer ID is formed in the peripheral surplus area surrounding the device area. Useful in the method.

21 Chuck table 25 Grinding wheel 30 Cutting device 31 Chuck table 32 Cutting blade C ID display D Device L Divided line T Grinding tape Tp Cutting tape W Wafer W1 Device area W2 Peripheral surplus area W2a Ring-shaped end material W3 Boundary W4 Dividing groove Wa Front Wb Back

Claims (1)

The back side of a wafer having a device region having a device and a division line on the surface and an outer peripheral surplus region surrounding the device region and having a wafer ID formed thereon is thinned to a finish thickness and processed along the division line. A wafer processing method,
A dividing groove forming step for forming a dividing groove that divides the device area and the outer peripheral surplus area at least halfway in the thickness direction of the wafer along the boundary between the device area and the outer peripheral surplus area,
After performing the dividing groove forming step, a grinding tape adhering step for adhering the grinding tape to the front surface side of the wafer;
After performing the grinding tape attaching step, holding the grinding tape side on the chuck table, and grinding to the finished thickness with the grinding wheel from the wafer back side;
After performing the grinding step, a transfer step of attaching a cutting tape to the ground surface of the wafer that has been ground, and peeling and transferring the grinding tape;
The ring-shaped end material of the device region and the outer peripheral surplus region of the wafer adhered to the cutting tape is placed on a chuck table of a cutting apparatus, and a cutting blade is attached to the ring-shaped end member of the outer peripheral surplus region and the device Cut the cutting tape halfway between the regions, feed the cut, raise the ring-shaped end material of the outer peripheral surplus region between the device region, and the wafer along the scheduled dividing line formed on the surface A dividing step for dividing the device area;
Consisting of
A wafer processing method characterized by identifying with a wafer ID formed on the ring-shaped end material in the outer peripheral surplus area in a later step.

Images