KR20170085949A - Wafer processing method - Google Patents

Abstract

An object of the present invention is to reduce the warpage of a wafer after formation of a modified layer and make it possible to carry.
A protective tape adhering step S11 for adhering the protective tape T to the surface WS of the wafer W and a back surface WR corresponding to the device area WA after the protective tape adhering step S11 A ring-shaped reinforcing portion forming step (S12) of grinding up to the first thickness t1 and forming a ring-shaped reinforcing portion WC on the back surface WR corresponding to the outer peripheral surplus portion WB; S12), the laser beam L is positioned inside the device area WA of the wafer W, and the device area WA of the wafer W along the line to be divided from the back surface WR of the wafer W A modified layer forming step S13 of forming a modified layer K in the interior of the wafer W and a step S13 of forming a modified layer are ground from the back surface WR of the wafer W to a final thickness t2, And a grinding step (S14) of dividing the wafer (W) along the line to be divided with the modified layer (K) as a starting point by grinding operation.

Description

[0001] WAFER PROCESSING METHOD [0002]

The present invention relates to a method of processing a wafer.

For example, it is known that when a relatively thick wafer having a thickness of 300 탆 or more is diced with a cutting blade, a large amount of backside chipping occurs. Therefore, a processing method called SDBG (Stealth Dicing Before Grinding) has been proposed in order to suppress the back chipping. The SDBG method is a combination of a laser processing method and a grinding method. More specifically, a laser beam of a wavelength having a transmittance to a wafer is first irradiated onto a wafer, and the laser beam is modulated at a predetermined depth along a line to be divided (a position at a depth equal to or greater than the finish thickness of the device chip from the wafer surface) And a crack layer extending from the modified layer toward the surface side of the wafer is formed. Thereafter, the back surface of the wafer is ground to thin the wafer to the finished thickness, and the wafer is divided by the grinding pressure and the crack layer is divided into individual device chips by dividing the wafer into individual device chips (see, for example, Patent Document 1).

[Patent Document 1] International Publication No. 2003/077295

However, when the wafer is conveyed to the grinding apparatus by the conveying means after the reforming layer is formed on the wafer by the laser processing apparatus, the wafer may be greatly bent due to the effect of the crack layer stretched after the formation of the modified layer, .

The present invention has been made in view of the above, and an object of the present invention is to provide a method of processing a wafer capable of reducing the warpage of the wafer after formation of the modified layer and transferring the wafer.

In order to solve the above-mentioned problems and to achieve the object, a method of processing a wafer according to the present invention is a method for processing a wafer comprising a device region having a plurality of devices and a plurality of dividing lines to be formed on a surface thereof and a wafer having an outer peripheral region surrounding the device region A method of processing a wafer to be processed, the method comprising: a protective tape adhering step of adhering a protective tape to the front surface side of the wafer; and a step of adhering the back surface corresponding to the device area to the first thickness by grinding means Shaped reinforcing portion is formed on the back surface corresponding to the outer peripheral surplus region, and a ring-shaped reinforcing portion forming step of forming a ring-shaped reinforcing portion on the back surface of the wafer, the laser beam having a transmittance to the wafer, The wafer is placed inside the device area, A modified layer forming step of forming a modified layer inside the device region of the wafer along a line along which the wafer is to be divided; and a step of forming a modified layer by grinding the back surface of the wafer by grinding means, And a grinding step of dividing the wafer along the line to be divided with the modified layer as a starting point by operation.

In addition, in the method of processing a wafer, before the protective tape adhering step is performed, the back side of the wafer is suction-held on the rotating chuck table, and the outer peripheral surplus area and the outer peripheral surplus area are removed from the surface side of the wafer by a cutting blade. And a ring-shaped cut groove forming step of forming a ring-shaped cut groove at the boundary between the outer peripheral free area and the device area by cutting the chuck table until the first thickness reaches the boundary of the device area, .

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

1 is a flowchart of a method of processing a wafer according to the first embodiment.
2 is a cross-sectional view showing an example of the configuration of a wafer in a protective tape adhering step in the method of processing a wafer according to the first embodiment.
Fig. 3 is a cross-sectional view showing a configuration example around the grinding means in the ring-shaped reinforcement forming step of the method of processing a wafer according to the first embodiment.
4 is a cross-sectional view showing a configuration example around the laser processing means in the modified layer forming step of the method of processing a wafer according to the first embodiment.
5 is a cross-sectional view showing a configuration example around the grinding means in the grinding step of the method for processing a wafer according to the first embodiment.
6 is an enlarged cross-sectional view showing an example of the configuration of a wafer in the grinding step of the method for processing a wafer according to the first embodiment.
7 is a cross-sectional view showing a configuration example around the grinding means in the grinding step of the method for processing a wafer according to the first embodiment.
8 is a flowchart of a method of processing a wafer according to the second embodiment.
Fig. 9 is a cross-sectional view showing a configuration example around the cutting means in the ring-shaped groove forming step of the method of processing a wafer according to the second embodiment.
10 is a cross-sectional view showing an example of the configuration of a wafer in the protective tape adhering step in the method of processing a wafer according to the second embodiment.
11 is a cross-sectional view showing a configuration example around the grinding means in the ring-shaped reinforcement forming step in the method of processing a wafer according to the second embodiment.
12 is a cross-sectional view showing a configuration example around the laser processing means in the modified layer forming step of the method of processing a wafer according to the second embodiment.
13 is a cross-sectional view showing a configuration example around the grinding means in the grinding step of the method for processing a wafer according to the second embodiment.
14 is a cross-sectional view showing a configuration example around the grinding means in the grinding step of the method for processing a wafer according to the second embodiment.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments according to the present invention will be described in detail with reference to the drawings. The present invention is not limited to the following embodiments. The constituent elements described below include those which can be readily devised by those skilled in the art and substantially the same. Further, the structures described below can be suitably combined. In addition, various omissions, substitutions or modifications can be made without departing from the gist of the present invention.

[First Embodiment]

1 is a flowchart of a method of processing a wafer according to the first embodiment. 2 is a cross-sectional view showing an example of the configuration of a wafer in a protective tape adhering step in the method of processing a wafer according to the first embodiment. Fig. 3 is a cross-sectional view showing a configuration example around the grinding means in the ring-shaped reinforcement forming step of the method of processing a wafer according to the first embodiment. 4 is a cross-sectional view showing a configuration example around the laser processing means in the modified layer forming step of the method of processing a wafer according to the first embodiment. 5 is a cross-sectional view showing a configuration example around the grinding means in the grinding step of the method for processing a wafer according to the first embodiment. 6 is an enlarged cross-sectional view showing an example of the configuration of a wafer in the grinding step of the method for processing a wafer according to the first embodiment. 7 is a cross-sectional view showing a configuration example around the grinding means in the grinding step of the method for processing a wafer according to the first embodiment.

The method of processing a wafer according to the present embodiment processes a wafer W having a device region in which a plurality of devices and a plurality of lines to be divided are formed on the surface and a peripheral region of surplus surrounding the device region. As shown in Fig. 1, the wafer is processed in the order of the protective tape adhering step S11, the ring-shaped reinforcement forming step S12, the modified layer forming step S13, and the grinding step S14 do.

First, a protective tape adhering step S11 is performed. 2, in the protective tape adhering step S11, the protective tape T is adhered to the side of the surface WS of the wafer W. More specifically, in the protective tape adhering step S11, the surface WS on which the device of the wafer W is formed and the adhesive layer Ta of the protective tape T are stacked and pressed by the roller 10, The protective tape T is adhered to the entire surface WS of the protective tape T. Then, the wafer W having the protective tape T is stored in a supply / recovery cassette (not shown). Then, the feed / withdrawal cassette is transferred to the grinding apparatus 20 by a feed mechanism or an operator (not shown) and received.

After the protective tape adhering step S11 is performed, the ring-shaped reinforcement forming step S12 is performed. In the ring-shaped reinforcement forming step S12, the first grinding means 30 of the grinding apparatus 20 is used.

The grinding apparatus 20 shown in Fig. 3 has a chuck table 21 for holding and holding the wafer W. The chuck table 21 is formed of a porous material having a large number of fine suction holes penetrating in the plate thickness direction. The chuck table 21 may hold the wafer W by vacuum chucking, or may be held by another method. The chuck table 21 is disposed on a turntable rotatable in a disc shape, for example, and is positionally displaceable. The chuck table 21 is provided so as to be independently rotatable in one direction or both directions by a rotation drive mechanism. In the present embodiment, the grinding apparatus 20 is provided with the first grinding means 30 and the second grinding means 40.

The first grinding means (30) is opposed to the chuck table (21). The first grinding means 30 is vertically movably attached by a support mechanism (not shown). The first grinding means 30 is attached to the chuck table 21 at a predetermined coarse grinding position of the grinding apparatus 20 so as to be vertically movable by a support mechanism (not shown) And is moved up and down by a not-shown feed drive mechanism composed of a ball nut, a motor, or the like, so that grinding and feeding can be performed. The first grinding means 30 has a plurality of segment grinding wheels 31 fixed in an annular shape. The turning diameter of the grinding wheel 31 is approximately half the diameter of the wafer W in order to grind the entire back surface WR of the wafer W corresponding to the device area WA.

In the ring-shaped reinforcement forming step S12, the back surface WR corresponding to the device area WA is ground by the first grinding means 30 of the grinding apparatus 20 up to the first thickness t1, A ring-shaped reinforcing portion WC is formed on the back surface WR corresponding to the region WB. In the ring-shaped reinforcement forming step S12, the surface WS of the wafer W is held on the chuck table 21, and the back surface WR of the wafer W corresponding to the device area WA is held The grinding unit 30 grinds the reinforcing portion WC into a concave shape (a north shape) while leaving the reinforcing portion WC. More specifically, first, one wafer W is taken out from the supply / withdrawal cassette, and the wafer W is sucked and held by the transfer pad of the transfer means (not shown) so that the back surface WR side of the wafer W is moved upward The surface WS of the wafer W is placed on the chuck table 21. In this state, Then, the grinding wheel 31 is positioned on the back surface WR of the wafer W corresponding to the device area WA. At this time, the grindstone position of the grinding stone 31 disposed at the outermost radial direction is located radially inward of the outer periphery of the wafer W by the width of the reinforced portion WC. Then, the grinding wheel 31 is processed and fed downward while rotating the grinding wheel 31, thereby pressing the grinding wheel 31 against the back surface WR of the wafer W. The chuck table 21 is also rotationally driven so that the attracted and held wafer W also rotates. The first grinding means 30 is processed and transferred downward until the thickness of the wafer W corresponding to the device region WA becomes the first thickness t1 to form the first grinding means 30 corresponding to the device region WA The back surface WR of the wafer W is ground. When the thickness of the wafer W corresponding to the device area WA becomes equal to the first thickness t1, the processing feed to the lower side of the first grinding means 30 is stopped. Thus, in the ring-shaped reinforcement forming step S12, the wafer W leaves the ring-shaped reinforcement WC on the back surface WR corresponding to the outer peripheral surplus area WB surrounding the device area WA And ground. The wafer W after grinding is sucked and held by the transfer pad of the transfer means and stored in the supply / recovery cassette. Then, the feed / withdrawal cassette is transferred to the laser machining apparatus 50 by a feed mechanism or an operator (not shown) and accommodated therein.

After the ring-shaped reinforcement forming step (S12) is performed, the modified layer forming step (S13) is performed. In the modified layer forming step (S13), the laser processing apparatus 50 is used.

The laser machining apparatus 50 shown in Fig. 4 irradiates the wafer W with a laser beam L. As shown in Fig. The laser processing apparatus 50 includes a chuck table 51 for holding a wafer W and a laser beam L having a wavelength which is transmissive to the wafer W on the wafer W held by the chuck table 51 (Not shown) for relatively moving the chuck table 51 and the laser beam irradiating means 52. The laser beam irradiating means 52 irradiates the chuck table 51 and the laser beam irradiating means 52 to form a modified layer K inside the wafer W, .

In the modified layer forming step S13, the laser beam L having a transmittance with respect to the wafer W is placed inside the device area WA of the wafer W to form the back surface WR of the wafer W, The modified layer K is formed in the device region WA of the wafer W along the expected line to be divided.

In the reformed layer forming step S13, one wafer W is taken out from the supply / recovery cassette, and the wafer W is sucked and held by the transfer pad of the transfer means (not shown) The surface WS of the wafer W is placed on the chuck table 51 of the laser machining apparatus 50 and the surface WS of the wafer W is placed on the chuck table 51, . Thereafter, alignment means (not shown) of the laser machining apparatus 50 performs alignment of the machining position. The chuck table 51 and the laser beam irradiating means 52 are relatively moved by the moving means so as to irradiate the wafer W from the back surface WR to the wafer W with a laser beam L ) Is irradiated along the line to be divided with the light-converging point set on the inside of the wafer W. Then, the modified layer K is formed in the wafer W along the line to be divided. Thus, in the modified layer forming step (S13), the modified layer K is formed in the wafer W along all the lines to be divided. The wafer W on which the modified layer K is formed is sucked and held by the transfer pad of the transfer means, and stored in the supply / withdrawal cassette. Then, the feed / withdrawal cassette is fed to the grinding apparatus 20 by a feed mechanism or an operator and accommodated.

An example of the processing conditions of the laser processing apparatus 50 in the reforming layer formation step (S13) is as follows.

Light source: YAG pulsed laser

Average power: 1.7 W

Repetition frequency: 90 kHz

Feeding speed: 700 mm / s

The modified layer (K) refers to a region in which the density, refractive index, mechanical strength, and other physical properties are different from that of the surroundings, and includes a molten processed region, a crack region, an insulating breakdown region, And the mixed region can be exemplified.

After the modified layer forming step (S13) is performed, the grinding step (S14) is performed. In the grinding step S14, the second grinding means 40 of the grinding apparatus 20 is used.

The second grinding means 40 shown in Fig. 5 is configured similarly to the first grinding means 30. The constituent elements of the second grinding means 40 are denoted by the same reference numerals as those of the first grinding means 30, and detailed description thereof will be omitted.

In the grinding step S14, as shown in Fig. 5, the grinding is performed by the second grinding means 40 from the back surface WR of the wafer W to the finish thickness t2 (see Fig. 7) 6, by generating a crack C starting from the modified layer K to the side of the surface WS of the wafer W by the grinding operation, Lt; / RTI > In the grinding step S14, the surface WS of the wafer W is held on the chuck table 21 and the back surface WR of the wafer W corresponding to the reinforcing portion WC is held by the second grinding means (40). More specifically, first, one wafer W is taken out from the supply / withdrawal cassette, and the wafer W is sucked and held by the transfer pad of the transfer means so that the back surface WR side of the wafer W faces upward The surface WS of the wafer W is placed on the chuck table 21. Then, Then, the grinding wheel 41 is placed on the back surface WR of the wafer W corresponding to the reinforcing portion WC. At this time, the grindstone position of the grinding stone 41 disposed at the outermost radial direction is positioned radially outwardly of the outer periphery of the wafer W. Then, the grinding stone 41 is processed and fed downward while rotating the grinding stone 41, thereby pressing the grinding stone 41 against the back surface WR of the wafer W. The chuck table 21 is also rotationally driven so that the attracted and held wafer W also rotates. 7, the reinforcing portion WC is removed and the second grinding means 40 is processed and fed downward until the thickness of the wafer W becomes the final thickness t2, The back surface WR of the wafer W corresponding to the reinforcing portion WC is ground. When the thickness of the wafer W corresponding to the device area WA becomes the final thickness t2, the processing of the lower portion of the second grinding means 40 is stopped. Thus, in the grinding step S14, the wafer W is ground with the final thickness t2 to remove the reinforcing portion WC. The processed wafers W are sucked and held by the transfer pads of the transfer means, and stored in the supply / withdrawal cassette.

6, the grinding stone 41 is pressed against the back surface WR of the wafer W in accordance with the grinding of the wafer W in the grinding step S14, A crack C starting from the surface WS of the wafer W is generated. The crack C extends toward the surface WS of the wafer W starting from the modified layer K as a starting point. In other words, the crack C is formed along the line to be divided.

The wafer W is reinforced by the ring-shaped reinforcing portion WC by performing the protective tape adhering step S11, the ring-shaped reinforcing portion forming step S12, the modified layer forming step S13, and the grinding step S14, The modified layer forming step S13 and the grinding step S14 are carried out in a state in which the modified layer K is formed.

As described above, according to the method of processing a wafer according to the present embodiment, in the ring-shaped reinforcement forming step (S12), the wafer W grinded in a concave shape (drum shape) , And the modified layer (K) is formed in the laser processing apparatus (50) in the modified layer forming step (S13). Therefore, even if the crack C is elongated from the modified layer K after the reformed layer K is formed in the reformed layer forming step S13, The warpage of the wafer W can be reduced.

The wafer W is conveyed from the laser processing device 50 to the second grinding means 40 for grinding in the grinding step S14 after the modified layer forming step S13 It is possible to convey the wafer to any kind of conveying means such as a conveying means for conveying the wafer in a state of being sucked and held. When the warp of the wafer W is large, a special jig considering warpage is required. However, according to the method of processing a wafer according to the present embodiment, warping of the wafer W is reduced, do. As described above, according to the method for processing a wafer according to the present embodiment, the processed wafer W can be easily conveyed regardless of the type of the conveying means.

[Second Embodiment]

The present embodiment will be described with reference to Figs. 8 to 14. Fig. 8 is a flowchart of a method of processing a wafer according to the second embodiment. Fig. 9 is a cross-sectional view showing a configuration example around the cutting means in the ring-shaped groove forming step of the method of processing a wafer according to the second embodiment. 10 is a cross-sectional view showing an example of the configuration of a wafer in the protective tape adhering step in the method of processing a wafer according to the second embodiment. 11 is a cross-sectional view showing a configuration example around the grinding means in the ring-shaped reinforcement forming step in the method of processing a wafer according to the second embodiment. 12 is a cross-sectional view showing a configuration example around the laser processing means in the modified layer forming step of the method of processing a wafer according to the second embodiment. 13 is a cross-sectional view showing a configuration example around the grinding means in the grinding step of the method for processing a wafer according to the second embodiment. 14 is a cross-sectional view showing a configuration example around the grinding means in the grinding step of the method for processing a wafer according to the second embodiment.

The method of processing a wafer according to the present embodiment is different from the method of processing a wafer of the first embodiment in that step S10 is performed before step S11 is performed in the flowchart shown in Fig. Do. The basic configuration of the apparatus used in each step of the present embodiment is the same as that used in each step of the first embodiment. In the following description, the same constituent elements as those of the apparatuses used in the respective steps of the first embodiment are denoted by the same reference numerals or corresponding symbols, and a detailed description thereof will be omitted.

8, the method for machining a wafer according to the present embodiment includes the steps of forming a ring-shaped cut groove (S10), attaching a protective tape (S11), forming a ring-shaped reinforcing portion (S12), forming a modified layer S13), and the grinding step (S14).

First, before the protective tape adhering step S11 is performed, a ring-shaped cutting groove forming step S10 is performed. In the ring-shaped cutting groove forming step S10, the cutting apparatus 60 is used.

The cutting apparatus 60 shown in Fig. 9 cuts the wafer W to form a ring-shaped cutting groove D. As shown in Fig. The cutting apparatus 60 has a chuck table 61 for holding the wafer W and a cutting means (cutting blade) 62 for cutting the wafer W held by the chuck table 61.

In the ring-shaped cutting groove forming step S10, one wafer W is taken out from a supply / withdrawal cassette (not shown), and the back side WR side of the wafer W is suction-held on the chuck table 61, From the surface WS side of the wafer W to the first thickness t1 at the boundary WD of the outer peripheral redundant area WB and the device area WA by the cutting means 62, Shaped cutting groove D is formed at the boundary WD of the outer peripheral redundant area WB and the device area WA by rotating the cutting edge 61. [ The depth of the cutting groove D may be less than the thickness of the wafer W by the first thickness t1 or more. The wafer W after cutting is sucked and held by a transfer pad of a transfer means (not shown), and is housed in a supply / withdrawal cassette.

After the ring-shaped groove forming step S10 is performed, the protective tape adhering step S11 is performed. 10, the cutting grooves D formed on the side of the surface WS of the wafer W are covered with the protective tape T. As shown in Fig. Then, the feed / withdrawal cassette is fed to the grinding apparatus 20 by a feed mechanism or an operator and accommodated.

After the protective tape adhering step S11 is performed, the ring-shaped reinforcement forming step S12 is performed. In the ring-shaped reinforcement forming step S12, one wafer W is taken out from the supply / recovery cassette and the wafer W is sucked and held by the transfer pad of the transfer means to transfer the surface WS of the wafer W, Is placed on the chuck table (21). 11, the grindstone position of the grinding wheel 31 disposed at the outermost radial direction is radially inward of the outer periphery of the wafer W by the width of the reinforcing portion WC, And is located on the back surface WR of the wafer W corresponding to the wafer W. When grinding is completed and the thickness of the wafer W corresponding to the device area WA becomes the first thickness t1, the inside of the reinforcing portion WC formed on the back surface WR of the wafer W, The groove D is exposed. Thus, in the ring-shaped reinforcement forming step S12, when the thickness of the wafer W becomes the first thickness t1 and the reinforcing portion WC is formed, the outer peripheral excess area WB is formed in the cutting groove D from the device area WA. At this time, the outer peripheral redundant area WB is held on the chuck table 21 together with the device area WA through the protective tape T. The wafer W after grinding is sucked and held by the transfer pad of the transfer means and stored in the supply / recovery cassette. Then, the supply / recovery cassette is transferred to and accommodated in the laser processing apparatus 50 by a transfer mechanism or an operator.

After the ring-shaped reinforcement forming step (S12) is performed, the modified layer forming step (S13) is performed. In the reforming layer forming step S13, first, one wafer W is taken out from the supply / recovery cassette, and the wafer W is sucked and held by the conveying pad of the conveying means so that the surface WS of the wafer W Is placed on the chuck table (51). 12, a laser beam L of a wavelength having a transmittance to the wafer W is placed inside the device area WA of the wafer W to form the back surface WR of the wafer W The modified layer K is formed in the device region WA of the wafer W along the line to be divided from the inner circumferential side of the cut groove D of the wafer W. Thus, in the modified layer forming step S13, the modified layer K is formed in the wafer W along all the lines to be divided in the device area WA. The wafer W on which the modified layer K is formed is sucked and held by the transfer pad of the transfer means, and stored in the supply / withdrawal cassette. Then, the feed / withdrawal cassette is fed to the grinding apparatus 20 by a feed mechanism or an operator and accommodated.

After the modified 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 / withdrawal cassette, and the wafer W is sucked and held by the transfer pad of the transfer means to transfer the surface WS of the wafer W to the chuck Is placed on the table (21). As shown in Fig. 13, the second grinding means 40 grinds the wafer W from the rear surface WR of the wafer W to be thinned to the final thickness t2, as shown in Fig. 14 The wafer W is divided along the line to be divided by generating a crack C starting from the modified layer K to the side of the surface WS of the wafer W by the grinding operation. Thus, in the grinding step S14, when the wafer W is ground to the finish thickness t2, the reinforcing portion WC is removed. Even if the crack C of the modified layer K is elongated in the grinding step S14 because the outer peripheral redundant region WB is separated from the device region WA with the cut groove D therebetween, The extension of the crack C to the outside in the radial direction of the wafer W is restricted by the cutting groove D. The processed wafers W are sucked and held by the transfer pads of the transfer means, and stored in the supply / withdrawal cassette.

As described above, according to the method of processing a wafer according to the present embodiment, even if the crack C is elongated from the modified layer K as in the first embodiment, by the ring-shaped reinforcing portion WC, The warp of the wafer W can be reduced because the wafer W is reinforced. Therefore, when the wafer W is transferred from the laser machining apparatus 50 to the second grinding means 40 for grinding in the grinding step S14 after the modified layer forming step S13, for example, It is possible to carry it by any kind of conveying means such as a conveying means for conveying in a state of being conveyed. As described above, according to the method for processing a wafer according to the present embodiment, the processed wafer W can be easily conveyed regardless of the type of the conveying means.

According to the method of processing a wafer according to the present embodiment, before the execution of the steps S11 to S14, in the ring-shaped groove forming step S10, It is possible to form the ring-shaped cutting groove D by inserting the boundary WD between the device area WA and the device area WA until the first thickness t1 is reached. When the thickness of the wafer W becomes the first thickness t1 and the reinforcing portion WC is formed in the ring-shaped reinforcing portion forming step S12, the outer peripheral excess area WB is formed between the cutting grooves D And can be separated from the device area WA. Thus, even if the crack C of the modified layer K formed on the wafer W is elongated in the grinding step S14, the processing method of the wafer is performed by the cutting groove D, It is possible to regulate the extension of the crack C radially outward.

The present invention is not limited to the above embodiment. In other words, various modifications can be made without departing from the scope of the present invention. For example, in the ring-shaped groove forming step S10, the depth of the cutting groove D is formed by cutting from the surface WS of the wafer W to the depth of t1. However, the depth of the cutting groove D May be less than the thickness of the wafer W by t1 or more.

20: grinding device 21: chuck table
30: first grinding means (grinding means) 31: grinding stone
40: second grinding means (grinding means) 41: grinding stone
50: laser processing device 51: chuck table
52: laser beam irradiation means 60: cutting device
61: chuck table 62: cutting means (cutting blade)
C: crack D: cutting groove
K: reformed layer L: laser beam
t1: first thickness t2: finish thickness
T: Protective tape W: Wafer
WA: Device area WB: Outer redundancy area
WC: reinforcement WD: boundary
WR: If WS: Surface

Claims (2)

A method of processing a wafer having a device region in which a plurality of devices and a plurality of lines to be divided are formed on a surface and an outer peripheral region surrounding the device region,
A protective tape adhering step of adhering a protective tape to the front side of the wafer,
A ring-shaped reinforcing portion forming step of grinding the back surface corresponding to the device area to the first thickness by grinding means after the protective tape adhering step and forming a ring-shaped reinforcing portion on the back surface corresponding to the outer peripheral excess area;
After the step of forming the ring-shaped reinforcing portion is performed, a laser beam of a wavelength having a transmittance to the wafer is positioned inside the device region of the wafer, and from the back surface of the wafer, along the expected dividing line, A modified layer forming step of forming a modified layer in the inside of the substrate,
And a grinding step of grinding the wafer from the back surface of the wafer by grinding means to reduce the wafer to a final thickness after the reforming layer forming step and dividing the wafer along the line to be divided with the modified layer as a starting point by grinding operation Wherein the wafer is processed. The method according to claim 1,
Wherein the wafer is held on the chuck table on a rotating chuck table by sucking and holding the back side of the wafer by suction from the front side of the wafer to the peripheral region, And cutting the chuck table so as to form a ring-shaped cutting groove at the boundary between the outer peripheral redundant area and the device area.

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