TWI729038B - Wafer processing method - Google Patents

Abstract

The subject of the present invention is to reduce the warpage of the wafer after the reforming layer is formed so that it can be formed and transported. The solution is to have: a protective tape attaching step, attaching a protective tape on the front side of the wafer; a ring-shaped reinforcing part formation step, after the protective tape attaching step, grinding the back surface corresponding to the component area to the first Thickness, and a ring-shaped reinforcement is formed on the back surface corresponding to the remaining area of the outer periphery; the reforming layer forming step, after the ring-shaped reinforcement forming step, the laser beam is positioned to the inside of the element area of the wafer and removed from the wafer The back surface of the wafer is formed along the predetermined dividing line to form a modified layer inside the element area of the wafer; and the grinding step, after the modified layer forming step, the back surface of the wafer is ground to be thinned to the thickness of the finished product, and by The grinding operation divides the wafer along the planned dividing line with the modified layer as a starting point.

Description

Wafer processing method

Field of invention

The invention relates to a wafer processing method.

Background of the invention

It is known that, for example, when a relatively thick wafer with a thickness of 300 μm or more is cut with a cutting blade, a large amount of backside chipping may occur. Therefore, in order to suppress back chipping, a processing method called SDBG (Stealth Dicing Before Grinding) method has been proposed. The SDBG method is a technology that combines the laser processing method and the grinding method. In more detail, it is to first irradiate a laser beam with a wavelength penetrating the wafer to the wafer, so as to be along the predetermined dividing line at a predetermined depth position (from the front of the wafer to the equivalent of the element wafer). A modified layer is formed at a position above the depth of the finished product thickness, and a crack layer extending from the modified layer toward the front side of the wafer is formed. After that, the backside of the wafer is ground to thin the wafer to the thickness of the finished product, and the wafer is divided into individual element wafers by grinding pressure with the crack layer as the starting point (see, for example, Patent Document 1) .

Prior art literature

Patent literature

Patent Document 1: International Publication No. 2003/077295

Summary of the invention

However, when a laser processing device is used to form a modified layer on a wafer, when the wafer is transported to a grinding device with a transfer assembly, there is a large warpage of the wafer under the influence of the crack layer that elongates after the reformed layer is formed. Doubts that make transportation difficult.

The present invention is an invention made in view of the above-mentioned circumstances, and its object is to provide a method for processing a wafer that can be transported by reducing the warpage of the wafer after the reforming layer is formed.

In order to solve the above-mentioned problems and achieve the objective, the wafer processing method of the present invention is to process a wafer with a device area on the front surface and a remaining area surrounding the device area, wherein the device area is formed with a plurality of elements and a plurality of divisions. For a predetermined line, the wafer processing method includes: a protective tape attaching step, attaching a protective tape on the front side of the wafer; a ring-shaped reinforcing portion forming step, after the protective tape attaching step is performed, by grinding The cutting assembly grinds the back surface corresponding to the element area to the first thickness, and forms a ring-shaped reinforcing part on the back surface corresponding to the remaining area of the outer periphery; the reforming layer forming step, after the ring-shaped reinforcing part forming step is performed , Position the laser beam with a wavelength penetrating the wafer to the inside of the device area of the wafer, and follow the predetermined dividing line from the back of the wafer A modified layer is formed inside the device area of the wafer; and a grinding step, after the modified layer forming step is implemented, the back surface of the wafer is thinned to the thickness of the finished product by grinding components, and The wafer is divided along the planned dividing line by the grinding operation with the modified layer as a starting point.

Furthermore, it is more desirable that the wafer processing method further includes a ring-shaped cutting groove forming step. The ring-shaped cutting groove forming step is to suck on a rotating work chuck before the protective tape attaching step is performed. Hold the back side of the wafer, and cut from the front side of the wafer to the first thickness at the boundary between the peripheral remaining area and the element area with a cutting knife, and rotate the work chuck to remain on the outer periphery The boundary between the area and the device area forms an annular cutting groove.

According to the wafer processing method of the present invention, the warpage of the wafer after the formation of the modified layer can be reduced and the wafer can be transported.

10: roller

20: Grinding device

21, 51, 61: working clamp table

30: The first grinding component (grinding component)

31, 41: Grinding grindstone

40: The second grinding component (grinding component)

50: Laser processing device

52: Laser beam irradiation component

60: Cutting device

62: Cutting assembly (cutter)

C: Fissure

D: Cutting groove

K: modified layer

L: Laser beam

S10, S11, S12, S13, S14: steps

t1: the first thickness

t2: Finished product thickness

T: Protective tape

Ta: Adhesive layer

W: Wafer

WA: component area

WB: Remaining area of outer periphery

WC: Reinforcement Department

WD: junction

WR: Back

WS: front

FIG. 1 is a flowchart of the wafer processing method of the first embodiment.

2 is a cross-sectional view showing a configuration example of a wafer in a protective tape attaching step of the wafer processing method of the first embodiment.

3 is a cross-sectional view showing a configuration example of the periphery of a grinding unit in the step of forming a ring-shaped reinforcing part in the wafer processing method of the first embodiment.

4 is a cross-sectional view showing a configuration example around the laser processing module in the step of forming a modified layer in the wafer processing method of the first embodiment.

5 is a cross-sectional view showing a configuration example of the periphery of a grinding unit in the grinding step of the wafer processing method of the first embodiment.

6 is an enlarged cross-sectional view showing an example of the structure of the wafer in the grinding step of the wafer processing method of the first embodiment.

FIG. 7 is a cross-sectional view showing a configuration example of the periphery of the grinding unit in the grinding step of the wafer processing method of the first embodiment.

Fig. 8 is a flowchart of a wafer processing method of the second embodiment.

9 is a cross-sectional view showing a configuration example of the periphery of the cutting unit in the step of forming an annular cutting groove in the wafer processing method of the second embodiment.

10 is a cross-sectional view showing an example of the structure of the wafer in the protective tape attaching step of the wafer processing method of the second embodiment.

11 is a cross-sectional view showing a configuration example of the periphery of the grinding assembly in the step of forming a ring-shaped reinforcing part in the wafer processing method of the second embodiment.

12 is a cross-sectional view showing a configuration example around the laser processing module in the step of forming a modified layer of the wafer processing method of the second embodiment.

13 is a cross-sectional view showing a configuration example of the periphery of the grinding unit in the grinding step of the wafer processing method of the second embodiment.

14 is a cross-sectional view showing a configuration example of the periphery of the grinding unit in the grinding step of the wafer processing method of the second embodiment.

The form used to implement the invention

Hereinafter, the embodiments of the present invention will be described with reference to the drawings. The present invention is not limited by the content described in the following embodiments. In addition, among the constituent elements described below, the present invention belongs to Those with ordinary knowledge in the technical field can easily imagine or are substantially the same. In addition, the configurations described below can be combined as appropriate. In addition, various omissions, substitutions, or changes to the configuration can be made as long as they do not depart from the gist of the present invention.

[First Embodiment]

FIG. 1 is a flowchart of the wafer processing method of the first embodiment. 2 is a cross-sectional view showing a configuration example of a wafer in a protective tape attaching step of the wafer processing method of the first embodiment. 3 is a cross-sectional view showing a configuration example of the periphery of a grinding unit in the step of forming a ring-shaped reinforcing part in the wafer processing method of the first embodiment. 4 is a cross-sectional view showing a configuration example around the laser processing module in the step of forming a modified layer in the wafer processing method of the first embodiment. 5 is a cross-sectional view showing a configuration example of the periphery of a grinding unit in the grinding step of the wafer processing method of the first embodiment. 6 is an enlarged cross-sectional view showing an example of the structure of the wafer in the grinding step of the wafer processing method of the first embodiment. FIG. 7 is a cross-sectional view showing a configuration example of the periphery of the grinding unit in the grinding step of the wafer processing method of the first embodiment.

The wafer processing method of this embodiment is to process a wafer W having a device area on the front surface and a peripheral remaining area surrounding the device area, wherein the device area is formed with a plurality of devices and a plurality of planned dividing lines. As shown in FIG. 1, the wafer processing method is to perform the processing in the order of the protective tape attaching step S11, the ring-shaped reinforcing portion forming step S12, the modified layer forming step S13, and the grinding step S14.

First, a protective tape attaching step S11 is implemented. As shown in Figure 2 As shown, in the protective tape attaching step S11, the protective tape T is attached to the front WS side of the wafer W. In more detail, in the protective tape attaching step S11, the front surface WS of the wafer W on which the device is formed is overlapped with the adhesive layer Ta of the protective tape T, and the protective tape T is attached to it while being pressed by the roller 10 The entire surface of the front side WS of the wafer W. Then, the wafer W to which the protective tape T has been attached is stored in a supply and recovery cassette not shown in the figure. In addition, the supply and recovery cassettes are transferred and stored in the grinding device 20 by a transfer mechanism or an operator not shown in the figure.

After the protective tape attaching step S11 is performed, the ring-shaped reinforcing portion forming step S12 is performed. In the step S12 of forming the ring-shaped reinforcing part, the first grinding assembly 30 of the grinding device 20 is used.

The grinding apparatus 20 shown in FIG. 3 includes a work chuck table 21 for sucking and holding a wafer W. As shown in FIG. The work clamp 21 is formed of a porous material having a plurality of small suction holes penetrating in the thickness direction of the plate. The work chuck 21 can adopt a vacuum chuck method to suck and hold the wafer W, or adopt other methods to hold it. The work chuck table 21 is, for example, provided on a disk-shaped and freely rotatable rotating table, so that the position can be replaced. The work chuck table 21 is independently rotatably installed in one direction or two directions by a rotating drive mechanism. In this embodiment, the grinding device 20 includes a first grinding unit 30 and a second grinding unit 40.

The first grinding assembly 30 will face the work clamping table 21. The first grinding assembly 30 is mounted so as to be freely up and down in the vertical direction by a support mechanism not shown in the figure. The first grinding assembly 30 is opposite to the work clamp table 21 at a predetermined rough grinding position of the grinding device 20, and is supported by a supporting mechanism not shown in the figure It is installed in the up and down direction so that it can be raised and lowered freely, and is raised and lowered by a feed drive mechanism (not shown) composed of a ball screw, a ball nut, and a motor, thereby forming a grinding feed. The first grinding assembly 30 has a plurality of segmented grinding stones 31 and the like fixed in a ring shape. In order to grind the back surface WR of the wafer W corresponding to the element area WA to cover the entire surface, the rotation diameter of the grinding stone 31 is set to approximately half of the diameter of the wafer W.

In step S12 of forming the ring-shaped reinforcing part, the back surface WR corresponding to the element area WA is ground to the first thickness t1 by the first grinding unit 30 of the grinding device 20, and the back surface corresponding to the outer peripheral remaining area WB is ground to the first thickness t1. A ring-shaped reinforcement WC is formed on the WR. In step S12 of forming a ring-shaped reinforcing part, the front WS side of the wafer W is held on the work chuck 21, and the first grinding assembly 30 leaves the reinforcing part WC and corresponds to the wafer in the device area WA The back WR of the W is ground into a concave shape (drum shape). In more detail, first, one wafer W is taken out from the supply and recovery cassette, and the wafer W is sucked and held by the transport pad of the transport unit (not shown), and the back side WR of the wafer W faces In the upper state, the front WS side of the wafer W is placed on the work chuck 21. And, the grinding stone 31 is positioned on the back surface WR of the wafer W corresponding to the element area WA. At this time, the grindstone position of the grinding grindstone 31 arranged on the outermost side in the radial direction is positioned on the inner side in the radial direction from the outer periphery of the wafer W corresponding to the width of the reinforcing portion WC. In addition, the grinding grindstone 31 is processed and fed downward while rotating the grinding grindstone 31 to press the grinding grindstone 31 against the back surface WR of the wafer W. By rotating the work chuck table 21, the sucked and held wafer W is also rotated. And, in the area corresponding to the component area WA Before the thickness of the wafer W reaches the first thickness t1, the first grinding unit 30 is processed and fed downward to grind the back surface WR of the wafer W corresponding to the element area WA. When the thickness of the wafer W corresponding to the element area WA becomes the first thickness t1, the downward processing and feeding of the first grinding assembly 30 is stopped. In this way, in step S12 of forming a ring-shaped reinforcing portion, the wafer W is ground by leaving a ring-shaped reinforcing portion WC on the back surface WR corresponding to the remaining area WB surrounding the outer periphery of the element area WA. The polished wafer W is sucked and held by the transfer pad of the transfer assembly, and stored in the supply and recovery cassette. In addition, the supply and recovery cassettes are transferred and stored in the laser processing apparatus 50 by a transfer mechanism or an operator not shown in the figure.

After performing step S12 of forming a ring-shaped reinforcing part, step S13 of forming a modified layer is performed. In the reforming layer forming step S13, a laser processing device 50 is used.

The laser processing device 50 shown in FIG. 4 irradiates the wafer W with a laser beam L. The laser processing apparatus 50 has a work chuck table 51 that holds the wafer W, and irradiates the wafer W held by the work chuck table 51 with a laser beam L having a wavelength penetrating to the wafer W, so as to irradiate the wafer W on the wafer W. The laser beam irradiation unit 52 in which the modified layer K is formed, and a moving unit (not shown) that moves the work clamp table 51 and the laser beam irradiation unit 52 relatively.

In the reforming layer forming step S13, the laser beam L having a wavelength penetrating to the wafer W is positioned inside the element area WA of the wafer W, and from the back surface WR of the wafer W along the planned dividing line A modified layer K is formed inside the element area WA of the wafer W.

In the reforming layer forming step S13, it is from the supply and recovery Take out a wafer W from the cassette, and hold the wafer W with the transfer pad of the transfer assembly not shown in the figure. With the back WR side of the wafer W facing up, the front WS of the wafer W The side is placed on the work chuck 51 of the laser processing device 50 to attract and hold the front WS side of the wafer W by the work chuck 51. After that, the calibration component not shown in the figure of the laser processing device 50 will complete the calibration of the processing position. Then, the work chuck 51 and the laser beam irradiation unit 52 are moved relatively by moving the unit, and the laser beam L with a wavelength that is penetrating to the wafer W is applied to the wafer W from the back side WR of the wafer W. The inside of W converges and converges the light spots and irradiates along the predetermined dividing line. In addition, a modified layer K is formed inside the wafer W along the planned dividing line. In this way, the modified layer K is formed in the inside of the wafer W along all the planned dividing lines in the modified layer forming step S13. The wafer W on which the modified layer K is formed is sucked and held by the transfer pad of the transfer unit, and is stored in the supply and recovery cassette. Then, the supply and recovery cassettes are transferred and stored in the grinding device 20 by a transfer mechanism or an operator.

An example of the processing conditions of the laser processing device 50 in the modified layer forming step S13 is as follows.

Light source: YAG pulse laser

Average output: 1.7W

Repetition frequency: 90kHz

Feed speed: 700mm/sec

The so-called modified layer K refers to a region where the density, refractive index, mechanical strength, or other physical properties are different from the surrounding properties, and can exemplify a melt-processed region, a crack region, and an insulating region. Damaged areas, refractive index change areas, etc., and areas where these areas are mixed, etc.

After the reforming layer forming step S13 is performed, the grinding step S14 is performed. In the grinding step S14, the second grinding assembly 40 of the grinding device 20 is used.

The second grinding unit 40 shown in FIG. 5 is constructed in the same manner as the first grinding unit 30. Among the constituent elements of the second grinding assembly 40, symbols corresponding to the constituent elements of the first grinding assembly 30 will be attached, and detailed descriptions will be omitted.

As shown in FIG. 5, in the grinding step S14, the back surface WR of the wafer W is ground by the second grinding unit 40 to be thinned to the finished thickness t2 (refer to FIG. 7), and as shown in FIG. 6 , By the grinding action, the crack C starting from the modified layer K is generated to the front WS side of the wafer W, thereby dividing the wafer W along the planned dividing line. In the grinding step S14, the front WS side of the wafer W is held on the work chuck 21, and the back WR of the wafer W corresponding to the reinforcing portion WC is ground by the second grinding unit 40. In more detail, one wafer W is taken out from the supply and recovery cassette, and the wafer W is sucked and held by the transport pad of the transport unit, and the backside WR side of the wafer W is turned up. The front WS side of the wafer W is placed on the work chuck 21. In addition, the grinding grindstone 41 is positioned on the back surface WR of the wafer W corresponding to the reinforcing portion WC. At this time, the grindstone position of the grinding grindstone 41 arranged on the outermost side in the radial direction is positioned on the outer side in the radial direction than the outer periphery of the wafer W. In addition, the grinding grindstone 41 is processed and fed downward while rotating the grinding grindstone 41 to press the grinding grindstone 41 against the back surface WR of the wafer W. Work folder The stage 21 is also rotationally driven, so that the sucked and held wafer W is also rotated. Then, as shown in FIG. 7, until the reinforcing portion WC is removed and the thickness of the wafer W becomes the finished thickness t2, the second grinding unit 40 is processed and fed downward to grind the portion corresponding to the reinforcing portion WC. The back side WR of the wafer W. When the thickness of the wafer W corresponding to the element area WA becomes the finished product thickness t2, the downward processing and feeding of the second grinding assembly 40 is stopped. In this way, in the grinding step S14, the wafer W is ground to the finished thickness t2 and the reinforcing portion WC is removed. The processed wafer W is sucked and held by the transfer pad of the transfer assembly, and is stored in the supply and recovery cassette.

In the grinding step S14, the grinding stone 41 is pressed against the back surface WR of the wafer W along with the grinding of the wafer W, whereby, as shown in FIG. 6, the modified layer K is The crack C at the starting point is formed to the front WS side of the wafer W. The crack C will extend to the front WS side of the wafer W from the modified layer K as a starting point. In other words, the crack C is formed along the predetermined dividing line.

Since the protective tape attaching step S11, the ring-shaped reinforcing part forming step S12, the modified layer forming step S13, and the grinding step S14 are carried out, the wafer W is reinforced with the ring-shaped reinforcing part WC. Since the modified layer forming step S13 and the grinding step S14 are implemented, the warpage of the wafer W after the modified layer K is formed can be reduced and the wafer W can be transported.

As described above, according to the wafer processing method of this embodiment, in the ring-shaped reinforcing portion forming step S12, the reinforcing portion WC is left and the wafer W is ground into a concave shape (drum shape). In the quality layer forming step S13, the laser processing device 50 is used to form the modified layer K. Therefore, after the reforming layer K in the reforming layer forming step S13 is formed, even if the crack C is removed from the reforming layer K With elongation, the wafer W can still be reinforced by the ring-shaped reinforcing portion WC, so the warpage of the wafer W can be reduced.

Since the warpage of the wafer W can be reduced, after the modified layer formation step S13, when the wafer W is transported from the laser processing device 50 to the second grinding assembly 40 for grinding in the grinding step S14, For example, it is possible to transport by any kind of transport assembly, such as a transport assembly that carries the wafer while sucking and holding the wafer. When the warpage of the wafer W is large, although a special jig to consider the warpage may be required, since the wafer processing method according to the present embodiment can reduce the warpage of the wafer W, it will not This kind of special fixture is needed. In this way, according to the wafer processing method of this embodiment, the processed wafer W can be easily transported without being limited to the type of transport unit.

[Second Embodiment]

With reference to FIG. 8 and FIG. 14, this embodiment will be described. Fig. 8 is a flowchart of a wafer processing method of the second embodiment. 9 is a cross-sectional view showing a configuration example of the periphery of the cutting unit in the step of forming an annular cutting groove in the wafer processing method of the second embodiment. 10 is a cross-sectional view showing an example of the structure of the wafer in the protective tape attaching step of the wafer processing method of the second embodiment. 11 is a cross-sectional view showing a configuration example of the periphery of the grinding assembly in the step of forming a ring-shaped reinforcing part in the wafer processing method of the second embodiment. 12 is a cross-sectional view showing a configuration example around the laser processing module in the step of forming a modified layer of the wafer processing method of the second embodiment. 13 is a cross-sectional view showing a configuration example of the periphery of the grinding unit in the grinding step of the wafer processing method of the second embodiment. Figure 14 shows the second real A cross-sectional view of a configuration example of the periphery of the grinding unit in the grinding step of the wafer processing method of the embodiment.

The wafer processing method of this embodiment is different from the wafer processing method of the first embodiment in that step S10 is performed before step S11 is performed in the flowchart shown in FIG. 1. The basic structure of the device used in each step of this embodiment is the same as the device used in each step of the first embodiment. In the following description, the same or corresponding symbols will be attached to the same components as those of the device used in each step of the first embodiment, and detailed descriptions thereof will be omitted.

As shown in FIG. 8, the wafer processing method of this embodiment is based on the ring-shaped cutting groove forming step S10, the protective tape attaching step S11, the ring-shaped reinforcing part forming step S12, the modified layer forming step S13, and the grinding step. The processing is performed in the order of S14.

First, before the implementation of the protective tape attaching step S11, the annular cutting groove forming step S10 will be performed first. In the annular cutting groove forming step S10, the cutting device 60 is used.

The cutting device 60 shown in FIG. 9 cuts the wafer W to form an annular cutting groove D. The cutting device 60 has a work chuck table 61 that holds the wafer W, and a cutting assembly (cutter) 62 that cuts the wafer W held by the work chuck table 61.

In the ring-shaped cutting groove formation step S10, one wafer W is taken out from the supply and recovery cassette not shown in the figure, and the back side WR of the wafer W is sucked and held on the work chuck 61, and the wafer The front WS side of W uses the cutting component 62 at the junction of the peripheral remaining area WB and the component area WA The WD is cut to the first thickness t1, and the work chuck 61 is rotated to form an annular cutting groove D at the boundary WD of the outer peripheral remaining area WB and the element area WA. The depth of the cutting groove D may be at least the first thickness t1 and lower than the thickness of the wafer W. The wafer W after cutting is sucked and held by a transfer pad of a transfer assembly not shown in the figure, and is stored in the supply and recovery cassette.

After the annular cutting groove forming step S10 is performed, the protective tape attaching step S11 is performed. As shown in FIG. 10, the cutting groove D formed on the front side WS of the wafer W is covered by the protective tape T. Then, the supply and recovery cassettes are transferred and stored in the grinding device 20 by a transfer mechanism or an operator.

After the protective tape attaching step S11 is performed, the ring-shaped reinforcing portion forming step S12 is performed. In step S12 of forming the ring-shaped reinforcing part, first, one wafer W is taken out from the supply and recovery cassette, and the wafer W is sucked and held by the transport pad of the transport unit, and the front side WS of the wafer W is loaded Place on the work clamp table 21. As shown in FIG. 11, the grindstone position of the grinding stone 31 arranged on the outermost side in the radial direction is positioned on the inner side in the radial direction corresponding to the width of the reinforcing portion WC from the outer periphery of the wafer W and corresponding to the crystal of the cutting groove D. The back of circle W is WR. When the grinding is completed and the thickness of the wafer W corresponding to the element area WA becomes the first thickness t1, the cutting groove D will be exposed inside the reinforcing portion WC formed on the back surface WR of the wafer W. In this way, when the thickness of the wafer W is set to the first thickness t1 in the ring-shaped reinforcing portion forming step S12 and the reinforcing portion WC is formed, the outer peripheral remaining area WB is separated from the element area WA with the cutting groove D sandwiched therebetween. At this time, the outer peripheral remaining area WB is held on the work chuck table 21 together with the component area WA via the protective tape T. After grinding The wafer W of is sucked and held by the transfer pad of the transfer assembly, and is stored in the supply and recovery cassette. Then, the supply and recovery cassettes are transferred and stored in the laser processing apparatus 50 by a transfer mechanism or an operator.

After performing step S12 of forming a ring-shaped reinforcing part, step S13 of forming a modified layer is performed. In the reforming layer forming step S13, firstly, one wafer W is taken out from the supply and recovery cassette, and the wafer W is sucked and held by the transport pad of the transport unit, and the front WS side of the wafer W is placed于Working clamp table 51. Then, as shown in FIG. 12, the laser beam L having a wavelength penetrating the wafer W is positioned inside the device area WA of the wafer W, and from within the cutting groove D on the back side WR of the wafer W A modified layer K is formed in the device region WA of the wafer W on the peripheral side along the planned dividing line. In this way, in the reforming layer forming step S13, the reforming layer K is formed inside the wafer W along all the planned dividing lines of the element region WA. The wafer W on which the modified layer K is formed is sucked and held by the transfer pad of the transfer unit, and is stored in the supply and recovery cassette. Then, the supply and recovery cassettes are transferred and stored in the grinding device 20 by a transfer mechanism or an operator.

After the reforming layer forming step S13 is performed, the grinding step S14 is performed. In the grinding step S14, first, one wafer W is taken out from the supply and recovery cassette, and the wafer W is sucked and held by the transfer pad of the transfer assembly, and the front WS side of the wafer W is placed on the work Clamping table 21 on. And, as shown in FIG. 13, the back surface WR of the wafer W is ground by the second grinding unit 40, and as shown in FIG. 14, the thickness is reduced to the finished product thickness t2, and the grinding action is used to change The crack C starting from the quality layer K occurs to the front WS side of the wafer W, thereby dividing the wafer W along the predetermined dividing line. Doing so while grinding When the wafer W is ground to the finished thickness t2 in the grinding step S14, the reinforcing part WC is removed. Since the outer peripheral remaining area WB is separated from the element area WA with the cutting groove D sandwiched therebetween, in the grinding step S14, even if the crack C of the modified layer K is elongated, the cutting groove D can restrict the crack C to crystallize. The extension of the circle W on the outside in the radial direction. The processed wafer W is sucked and held by the transfer pad of the transfer assembly, and is stored in the supply and recovery cassette.

As described above, according to the wafer processing method of this embodiment, as in the first embodiment, even if the crack C extends from the modified layer K, the wafer W can be reinforced through the ring-shaped reinforcing portion WC, so it can Reduce the warpage of wafer W. Therefore, after the reforming layer forming step S13, when the wafer W is transported from the laser processing device 50 to the second grinding assembly 40 in order to be ground in the grinding step S14, for example, the wafer is held in the state of being sucked and held. It is possible to transport any kind of transport components such as the transport components that are transported under the next. In this way, according to the wafer processing method of this embodiment, the processed wafer W can be easily transported without being limited to the type of transport unit.

According to the wafer processing method of this embodiment, before the implementation of steps S11 to S14, in step S10 of forming a ring-shaped cutting groove, the outer peripheral remaining area WB and the device area WA are removed from the front side WS of the wafer W. The boundary WD is cut to the first thickness t1, whereby the annular cutting groove D can be formed. In the ring-shaped reinforcing portion forming step S12, when the thickness of the wafer W is set to the first thickness t1 and the reinforcing portion WC is formed, the outer peripheral remaining area WB can be separated from the element area WA with the cutting groove D interposed therebetween. Thereby, in the processing method of the wafer, in the grinding step S14, even if the modified layer K of the wafer W is formed Since the crack C of φ is elongated, the elongation of the crack C to the radially outer side of the wafer W can also be restricted by the cutting groove D.

In addition, the present invention is not limited to the above-mentioned embodiment. That is, various modifications can be made and implemented without departing from the gist of the present invention. For example, in the annular cutting groove formation step S10, although the cutting groove D is cut to a depth t1 from the front surface WS of the wafer W, the description will be made, but the depth of the cutting groove D should be t1 or more. It should be less than the thickness of the wafer W.

S11, S12, S13, S14‧‧‧Step

Claims (2)

A method for processing a wafer is to process a wafer with a device area on the front side and a remaining area surrounding the device area, wherein the device area is formed with a plurality of devices and a plurality of predetermined dividing lines. The processing method of the wafer It is equipped with: a protective tape attaching step, attaching a protective tape on the front side of the wafer; a ring-shaped reinforcing part forming step, after the protective tape attaching step is implemented, the components corresponding to the component area are ground The back surface is ground to the first thickness, and a ring-shaped reinforcement portion is formed on the back surface corresponding to the remaining area of the outer periphery; the reforming layer forming step, after the ring-shaped reinforcement portion forming step is implemented, will penetrate the wafer A laser beam of a sexual wavelength is positioned inside the device area of the wafer, and a modified layer is formed in the device area of the wafer along the predetermined dividing line from the back of the wafer; and grinding Step, after the reforming layer forming step is implemented, the back surface of the wafer is ground by a grinding assembly to remove the aforementioned ring-shaped reinforcing part and thin it to the thickness of the finished product, and the aforementioned modification is performed by the grinding action. The quality layer serves as a starting point to divide the wafer along the aforementioned planned dividing line. For example, the wafer processing method of claim 1, further comprising a ring-shaped cutting groove forming step. The ring-shaped cutting groove forming step is to attract and hold the protective tape on a rotatable work chuck before the step of attaching the protective tape. The back side of the wafer, and from the front side of the wafer, use a cutting knife to cut into the first thickness at the boundary between the remaining peripheral area and the device area, and make the The working chuck rotates to form an annular cutting groove at the boundary between the remaining area of the outer periphery and the element area.

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