TWI623030B - Wafer processing method - Google Patents

Abstract

An object of the present invention is to provide a method of processing a wafer that can be internally processed even when an insulating reinforcing sheet is attached to the back surface of the wafer. The solution is to form a wafer in which a device is formed by dividing a predetermined line by a plurality of lines on a surface and forming a lattice in a plurality of regions divided by a plurality of predetermined lines, and dividing the crystal into individual devices along the dividing line. The method for processing a circle, comprising: a step of attaching a protective member to which a protective member is attached on a surface of the wafer, a back grinding step of grinding the back surface of the wafer to form a predetermined thickness, and having a wafer having a predetermined thickness from a back side of the wafer The laser beam of the penetrating wavelength internally locates the condensed spot to illuminate along the dividing line, and further forms a modified layer forming step of the modified layer inside the wafer along the dividing line, on the back side of the wafer a reinforcing sheet mounting step with an insulating function reinforcing sheet, a heating sheet for heating the reinforcing sheet to cure the reinforcing sheet, and a dicing tape attached to the cured reinforcing sheet mounted on the back surface of the wafer, and a wafer supporting step of mounting the outer peripheral portion of the dicing tape on the annular frame, and an external force applied to the wafer to divide the wafer into individual devices, and at the same time, the reinforcing sheets are arranged along one device Crack segmentation step.

Description

Wafer processing method Field of invention

The present invention relates to a wafer in which a device is formed by dividing a predetermined line by a plurality of lines on a surface while forming a grid in a plurality of regions divided by the plurality of predetermined lines, and dividing along the dividing line. Wafer processing method.

Background of the invention

In the semiconductor device manufacturing step, the surface of the semiconductor wafer having a substantially disk shape is divided into a plurality of regions by a predetermined dividing line arranged in a lattice shape, and devices such as ICs and LSIs are formed in the divided regions. Further, the semiconductor wafer thus formed can be cut along the dividing line to divide the region in which the device is formed to manufacture a single device.

The cutting along the predetermined dividing line of the semiconductor wafer is usually performed by a cutting device called a Dicer. The cutting device includes a chuck table for holding a workpiece such as a semiconductor wafer and an optical device wafer, a cutting mechanism for cutting a workpiece to be held on the chuck table, and a chuck table and a cutting mechanism Moving cutting conveyor. The cutting mechanism includes a spindle unit including a rotating spindle and a cutting blade mounted on the spindle and a driving mechanism that rotationally drives the rotating spindle. Cutting insert is made up of The disk-shaped base and the annular blade attached to the outer peripheral portion of the side surface of the base are formed by electroforming, for example, diamond abrasive grains having a particle diameter of about 3 μm are fixed to the base to form a thickness of about 20 μm. about.

However, since the cutting insert has a thickness of about 20 μm, the width of the dividing line of the dividing device must be about 50 μm, which increases the ratio of the area occupied by the dividing line to the area of the wafer, and has a problem of poor productivity. .

On the other hand, in recent years, as a method of dividing a wafer such as a semiconductor wafer, a pulsed laser beam having a wavelength penetrating the wafer is used, and a light collecting point is positioned inside the divided region to perform pulse laser irradiation. The laser processing method called the internal processing of the irradiation of light has also been put into practical use. The method of segmentation using a laser processing method called internal processing is to irradiate a laser beam of light from a surface side of one side of the wafer to a condensing point to illuminate a wavelength that is transparent to the wafer. And a technique of continuously forming a reforming layer in the inside of the wafer along the dividing line, and applying an external force along the dividing line which is reduced in strength by forming the reforming layer, thereby breaking the wafer and dividing the wafer (refer to For example, Patent Document 1).

Prior technical literature Patent literature

Patent Document 1: Japanese Patent No. 3408805

Summary of invention

And because the surface area layer of the wafer has a plurality of layers constituting the device The functional layer, therefore, to position the spot of the pulsed laser light inside the wafer for internal processing, it is necessary to illuminate the laser beam from the back side of the wafer.

However, on the wafer on which the semiconductor device is formed by stacking the upper and lower layers, an insulating reinforcing sheet is attached to the back surface of the wafer in advance, because the reinforcing sheet blocks the laser light and cannot be removed from the wafer. The back side performs the problem of internal processing.

The present invention has been made in view of the above circumstances, and a main technical object thereof is to provide a method of processing a wafer that can perform internal processing even when an insulating reinforcing sheet is attached to the back surface of a wafer.

In order to solve the above-mentioned main technical problems, the method for processing a wafer according to the present invention is to form a plurality of regions in which a plurality of predetermined lines are formed on a surface in a lattice shape and are divided by a plurality of predetermined lines. a method of processing a wafer in which a device is formed and divided into individual devices along a dividing line, characterized in that it comprises: a protective member attaching step, attaching a protective member to the wafer surface; and a back grinding step, The protective member side of the wafer to which the protective member is attached is held on the chuck table of the grinding device through the protective member attaching step, and the back surface of the wafer is ground to form a predetermined thickness; the modified layer a forming step of holding the protective member side of the wafer formed to a predetermined thickness through the back grinding step on the chuck table of the laser processing apparatus, and penetrating the wafer from the back side of the wafer The laser light of the wavelength internally locates the condensed spot to illuminate along the dividing line, thereby forming a modified layer inside the wafer along the dividing line; In the reinforcing sheet mounting step, a reinforcing sheet having an insulating function is mounted on the back surface of the wafer on which the reforming layer forming step is performed; and the reinforcing sheet heating step is performed on the back surface of the wafer through the reinforcing sheet mounting step. The reinforcing sheet is heated to cure the reinforcing sheet; in the wafer supporting step, the dicing tape is attached to the cured reinforcing sheet mounted on the back surface of the wafer on which the reinforcing sheet is heated, and the outer peripheral portion of the dicing tape is attached Mounted on the annular frame; and a dividing step of imparting a wafer external force to the wafer supporting step, and dividing the wafer into a plurality of devices along a dividing line formed with the modified layer, and along one The device breaks the reinforcing sheet.

In the above-described reinforcing sheet heating step, the reinforcing sheet is heated in a state in which the protective member is attached to the surface of the wafer, and the protective member peeling step of peeling the protective member is performed before the step of dividing.

After the reinforcing sheet mounting step is performed, a reinforcing sheet cooling step is performed before the reinforcing sheet heating step is performed, and the reinforcing sheet mounted on the back surface of the wafer is cooled to reduce the viscosity, and the reinforcing sheet is to be implemented. After the cooling step is performed to hold the reinforcing sheet side having a reduced viscosity on the chuck table, a protective member peeling step is performed to peel off the protective member attached to the wafer surface.

After the above-described reinforcing sheet heating step is carried out, a printing step may be performed to irradiate the region corresponding to each device in the reinforcing sheet with laser light to print an ID mark for identifying the device.

In the method of processing a wafer of the present invention, the protective member is attached to the surface of the wafer, and the protective member is held by the grinding device. a chucking stage for grinding the back surface of the wafer, grinding to a predetermined thickness of the back grinding step, and maintaining the laser on the side of the protective member to be ground to a predetermined thickness of the wafer On the chuck table of the processing device, the laser light having a wavelength penetrating the wafer from the back side of the wafer is internally positioned as a light collecting point and irradiated along a dividing line to be along the dividing line. After the reforming layer forming step of forming the modified layer inside the wafer, the reinforcing sheet mounting step of mounting the reinforcing sheet having the insulating function on the back surface of the wafer is performed, so that the reinforcing member is attached to the back surface of the wafer. In the case of a sheet, a reforming layer forming step as an internal processing in which a modified layer is formed inside the wafer along a predetermined dividing line may be performed. Further, since the reinforcing sheet mounted on the back surface of the wafer can be heated to cure the reinforcing sheet, the wafer can be divided into individual devices along the dividing line on which the modified layer is formed by applying the external force of the wafer, and simultaneously The reinforcing sheets are broken along a single device.

2‧‧‧Semiconductor wafer

2a‧‧‧ surface

2b‧‧‧back

21‧‧‧ dividing line

210‧‧‧Modified layer

22‧‧‧ device

3‧‧‧Protection tape

4‧‧‧ grinding device

41, 51, 101‧‧‧ chuck table

41a, 424a, 424b, X, Y‧‧ arrow

42‧‧‧grinding mechanism

421‧‧‧ spindle housing

422‧‧‧Rotating spindle

423‧‧‧After

424‧‧‧ grinding wheel

425‧‧‧Abutment

426‧‧‧ grinding grinding stone

427‧‧‧Link bolt

5‧‧‧ Laser processing equipment

52‧‧‧Laser light irradiation mechanism

521‧‧‧ casing

522‧‧‧ concentrator

53‧‧‧ camera organization

6‧‧‧ Strengthening film

7‧‧‧ heating device

71, 91‧‧‧Processing box

72, 92‧‧‧ lid

73, 93‧‧‧Processed object placement table

74‧‧‧heater

8‧‧‧ tape expansion device

81‧‧‧Framekeeping agency

811‧‧‧Frame holding members

811a‧‧‧Loading surface

812‧‧‧ fixture

82‧‧‧ tape expansion mechanism

821‧‧‧Expansion roller

822‧‧‧Support flange

823‧‧‧Support institutions

823a‧‧ ‧ cylinder

823b‧‧‧ piston rod

83‧‧‧ picking chucks

9‧‧‧Cooling device

94‧‧‧Air-jet nozzle

10‧‧‧ peeling device

F‧‧‧Ring frame

P‧‧‧ spotlight

S‧‧‧ interval

T‧‧‧ cutting tape

1 is a perspective view of a semiconductor wafer as a wafer that is divided by the method of processing a wafer of the present invention.

2(a) and 2(b) are explanatory views showing a step of attaching a protective member in the method of processing a wafer of the present invention.

3 is a perspective view of a main part of a grinding apparatus for performing a back grinding step in a method of processing a wafer of the present invention.

4 is an explanatory view showing a back grinding step in the method of processing a wafer of the present invention.

Fig. 5 is a perspective view of a main part of a laser processing apparatus for carrying out a reforming layer forming step in the method for processing a wafer of the present invention.

6(a) and 6(b) are explanatory views showing a reforming layer forming step in the method of processing a wafer of the present invention.

7(a) and 7(b) are explanatory views of the reinforcing sheet mounting step in the method of processing a wafer of the present invention.

Fig. 8 is an explanatory view showing a heating step of a reinforcing sheet in the method of processing a wafer of the present invention.

Fig. 9 is an explanatory view showing a printing step in the method of processing a wafer of the present invention.

10(a) and 10(b) are explanatory views showing a wafer supporting step in the method of processing a wafer of the present invention.

Fig. 11 is an explanatory view showing a step of peeling off a protective member in the method of processing a wafer of the present invention.

Fig. 12 is a perspective view of a tape expanding device for performing a dividing step in the method of processing a wafer of the present invention.

13(a) and 13(b) are explanatory views showing a dividing step in the method of processing a wafer of the present invention.

14(a) and 14(b) are explanatory views showing a pickup step in the method of processing a wafer of the present invention.

Fig. 15 is an explanatory view showing a step of cooling a reinforcing sheet in the method of processing a wafer of the present invention.

Figs. 16(a) and 16(b) are explanatory views showing another embodiment of the protective member peeling step in the method of processing a wafer of the present invention.

Form for implementing the invention

Hereinafter, a preferred embodiment of the wafer processing method of the present invention will be described in detail with reference to the accompanying drawings.

1 is a perspective view of a semiconductor wafer as a wafer to be processed in accordance with the present invention. The semiconductor wafer 2 shown in FIG. 1 is made of a tantalum wafer having a thickness of, for example, 500 μm, and is formed in a lattice shape by dividing a predetermined line 21 by a plurality of strips on the surface 2a, and dividing the predetermined line 21 by the plurality of strips. Devices 22 such as ICs and LSIs are formed in a plurality of divided regions. Hereinafter, a method of processing a wafer in which the semiconductor wafer 2 is divided into individual devices 22 along the dividing line 21 will be described.

First, in order to protect the device 22 formed on the surface 2a of the semiconductor wafer 2, a protective member attaching step of attaching a protective member to the surface 2a of the semiconductor wafer 2 is performed. That is, as shown in FIG. 2, a protective tape 3 as a protective member is attached to the surface 2a of the semiconductor wafer 2. Further, in the illustrated embodiment, the protective tape 3 is an acrylic resin-coated adhesive having a thickness of about 5 μm on the surface of a sheet-like substrate made of polyvinyl chloride (PVC) having a thickness of 100 μm. And formed.

After the protective tape 3 as a protective member is attached to the surface 2a of the semiconductor wafer 2, a back grinding step can be performed to hold the protective member side of the semiconductor wafer 2 on the chuck table of the grinding device, and The back surface of the semiconductor wafer 2 is ground to be ground to a predetermined thickness. This back grinding step is carried out using the grinding device 4 shown in FIG. The grinding device 4 shown in Fig. 3 includes a chuck table 41 for holding a workpiece, and a grinding mechanism 42 for grinding a workpiece held on the chuck table 41. The chuck table 41 is configured to attract and hold the workpiece on the top surface, and can be wound by a rotary drive mechanism (not shown) In Fig. 3, the direction is indicated by an arrow 41a. The grinding mechanism 42 includes a spindle housing 421, a rotary spindle 422 that is rotatably supported by the spindle housing 421 and that is rotated by a rotary drive mechanism (not shown), and a base that is attached to the lower end of the rotary spindle 422. 423, and a grinding wheel 424 mounted on a bottom surface of the base 423. The grinding wheel 424 is composed of an annular base 425 and a grinding stone 426 which is annularly mounted on the bottom surface of the base 425, and the base 425 is attached by a coupling bolt 427. The bottom surface of the base 423.

When the above-described back grinding step is carried out using the above-described grinding device 4, the protective tape 3 side of the semiconductor wafer 2 on which the protective member attaching step is applied is placed on the chuck stage 41 as shown in FIG. The top surface (holding surface). Then, the semiconductor wafer 2 is adsorbed and held by the chucking stage 41 through the protective tape 3 by a suction mechanism (not shown) (wafer holding step). As a result, the semiconductor wafer 2 held on the chuck stage 41 becomes the upper side 2b on the upper side. After the semiconductor wafer 2 is sucked and held on the chuck stage 41 through the protective tape 3 as described above, the chuck stage 41 can be ground while rotating in the direction indicated by the arrow 41a in FIG. 3 at, for example, 300 rpm. The grinding wheel 424 of the mechanism 42 rotates at a direction indicated by an arrow 424a in FIG. 3 at, for example, 6000 rpm, and as shown in FIG. 4, the grinding stone 426 is brought into contact with the back surface 2b of the semiconductor wafer 2 to be processed. And, as shown by an arrow 424b in FIGS. 3 and 4, the grinding wheel 424 is ground downward (in a direction perpendicular to the holding surface of the chuck table 41) at a grinding transmission speed of, for example, 1 μm/second. the amount. As a result, the back surface 2b of the semiconductor wafer 2 is ground, and the semiconductor wafer 2 is formed to a predetermined thickness (for example, 100 μm).

Next, a reforming layer forming step is performed, which has been ground to a predetermined thickness The protective member side of the semiconductor wafer 2 is held on the chuck table of the laser processing apparatus, and the laser light having a wavelength penetrating the semiconductor wafer 2 is internally positioned from the back side of the semiconductor wafer 2. The light collecting spot is irradiated along the dividing line, and a modified layer is formed inside the semiconductor wafer 2 along the dividing line. This reforming layer forming step is carried out using the laser processing apparatus 5 shown in FIG. The laser processing apparatus 5 shown in FIG. 5 includes a collet table 51 that holds a workpiece, and a laser beam irradiation mechanism 52 that irradiates a workpiece to be held on the chuck table 51 with laser light, and The imaging mechanism 53 that holds the workpiece held by the chuck table 51 is imaged. The chuck table 51 is configured to attract and hold the workpiece, and is formed in a processing conveyance direction indicated by an arrow X in FIG. 5 and an index transmission direction indicated by an arrow Y by a moving mechanism not shown. mobile.

The laser beam irradiation unit 52 irradiates the pulsed laser beam from the concentrator 522 provided at the tip end of the sleeve 521 which is substantially horizontally arranged in a horizontal shape. Further, the imaging unit 53 is disposed at the distal end portion of the sleeve 521 constituting the laser beam irradiation unit 52. In the illustrated embodiment, in addition to a general image sensor (CCD) that images by visible light, An infrared illuminating mechanism for irradiating infrared rays to a workpiece, an optical system for capturing infrared rays irradiated by the infrared illuminating mechanism, and an image sensor for outputting an electric signal corresponding to infrared rays captured by the optical system ( The infrared CCD is configured to transmit the captured image signal to a control unit to be described later.

The reforming layer forming step performed by the above-described laser processing apparatus 5 will be described with reference to FIGS. 5 and 6.

In the reforming layer forming step, first, the side of the protective tape 3 of the semiconductor wafer 2 subjected to the above-described grinding step is placed on the chuck stage 51 of the laser processing apparatus 5 shown in FIG. Then, the semiconductor wafer 2 is adsorbed and held on the chuck stage 51 by the protective tape 3 by a suction mechanism (not shown) (wafer holding step). As a result, the semiconductor wafer 2 held on the chuck stage 51 becomes the upper side of the back surface 2b. In this manner, the chuck stage 51 that sucks and holds the semiconductor wafer 2 can be positioned directly below the image pickup mechanism 53 by a processing transfer mechanism not shown.

After the chuck table 51 is positioned directly under the image pickup mechanism 53, the alignment of the processing region for laser processing of the semiconductor wafer 2 for laser processing can be performed by the image pickup mechanism 53 and a control mechanism not shown. operation. That is, the imaging unit 53 and the control unit (not shown) perform laser light irradiation for dividing the predetermined line 21 formed in the predetermined direction of the semiconductor wafer 2 and irradiating the laser beam along the dividing line 21 . The concentrator 522 of the mechanism 52 performs image processing such as pattern matching of the position alignment to complete the calibration of the position of the laser beam irradiation. Further, the alignment of the laser beam irradiation position is similarly performed on the planned dividing line 21 formed on the semiconductor wafer 2 in a direction perpendicular to the predetermined direction. At this time, although the surface 2a of the semiconductor wafer 2 on which the planned dividing line 21 is formed is located on the lower side, the imaging unit 53 includes an infrared illuminating mechanism, an optical system capable of capturing infrared rays, and an electric system corresponding to infrared rays as described above. Since the image sensor (infrared CCD) such as a signal is output, the image forming means 21 can be imaged by the back surface 2b.

As described above, the predetermined planned line 21 formed on the semiconductor wafer 2 held on the chuck stage 51 is detected, and the position of the laser beam irradiation position is calibrated, as shown in Fig. 6(a). As shown, the chuck stage 51 is moved to the laser beam irradiation area where the concentrator 522 of the laser beam irradiation mechanism 52 that irradiates the laser beam is placed, and one end of the predetermined division line 21 is predetermined (in Fig. 6 (a The middle side is positioned directly below the concentrator 522 of the laser beam illumination mechanism 52. Next, the condensed spot P of the pulsed laser light irradiated from the concentrator 522 can be positioned to the intermediate portion in the thickness direction of the semiconductor wafer 2. Further, while irradiating the laser beam ray from the concentrator 522 with a wavelength that is transparent to the silicon wafer, the chuck stage 51, that is, the semiconductor wafer 2, is transported at a predetermined transfer speed along the line of FIG. 6(a). Move in the direction indicated by the arrow X1. Further, as shown in Fig. 6(b), when the irradiation position of the concentrator 522 of the laser beam irradiation means 52 reaches the other end of the division planned line 21, the irradiation of the pulsed laser light is stopped, and the chuck is stopped. The movement of the stage 51, that is, the semiconductor wafer 2. As a result, the reforming layer 210 is formed along the planned dividing line 21 inside the semiconductor wafer 2.

Further, the processing conditions of the reforming layer forming step are set under the following conditions, for example.

Wavelength: 1064nm pulsed laser

Repeat frequency: 100kHz

Average output: 0.3W

Spot point diameter: φ1μm

Processing transfer speed: 100mm / sec

The above is performed along the predetermined dividing line 21 as described above. After the reforming layer forming step, the chuck stage 51 is only indexed in the direction indicated by the arrow Y by the distance between the dividing lines 21 formed on the semiconductor wafer 2 (index transfer step), and the above modification is completed. The layer formation step. By performing the above-described reforming layer forming step along all the dividing line 21 formed in the predetermined direction, the chuck table 51 can be rotated by 90 degrees so as to be along the opposite direction formed in the predetermined direction. The dividing line 21 on which the dividing planned line 21 extends in the vertical direction performs the above-described reforming layer forming step.

When the reforming layer 210 is formed inside the semiconductor wafer 2 along the dividing line 21 by performing the above-described reforming layer forming step, the reinforcing sheet having the insulating function can be mounted on the semiconductor wafer 2. Reinforcement sheet mounting steps on the back. That is, as shown in FIGS. 7(a) and 7(b), the reinforcing sheet 6 having the insulating function can be mounted on the back surface of the semiconductor wafer 2 having the modified layer 210 formed therein along the dividing line 21; 2b. Further, the reinforcing sheet 6 is formed of a resin sheet which has a viscosity and which is degraded when cooled, and which is cured after heating. Since the reinforcing sheet mounting step is performed after the above-described modified layer forming step is performed, even when the insulating reinforcing sheet 6 is attached to the back surface of the semiconductor wafer 2, it can be implemented along The division planned line 21 forms a modified layer forming step of the modified layer 210 as an internal processing inside the semiconductor wafer 2.

Next, a reinforcing sheet heating step may be performed to heat the reinforcing sheet 6 mounted on the back surface of the semiconductor wafer 2 to cure the reinforcing sheet 6. This reinforcing sheet heating step is carried out using the heating device 7 shown in FIG. The heating device 7 is a process cartridge 71 that has an upper end opened, a lid 72 that closes the upper end of the process cartridge 71, and a workpiece that is placed in the process cartridge 71 and placed on the workpiece. The mounting table 73 and the heater 74 disposed on the inner surface of the cover 72 are formed. When the reinforcing sheet heating step is performed using the heating device 7 configured as described above, the lid 72 is opened to place the side of the protective tape 3 attached to the surface of the semiconductor wafer 2 on the workpiece mounting table 73. As a result, the reinforcing sheet 6 attached to the back surface of the semiconductor wafer 2 placed on the workpiece mounting table 73 is on the upper side. In this manner, the side of the protective tape 3 adhered to the surface of the semiconductor wafer 2 is placed on the workpiece mounting table 73, and after the upper lid 72 is closed, the heater 74 can be actuated to be mounted on the heating. The reinforcing sheet 6 on the back surface of the semiconductor wafer 2 on the workpiece mounting table 73. In this reinforcing sheet heating step, it was heated at 130 ° C for 2 hours. As a result, the reinforcing sheet 6 mounted on the back surface of the semiconductor wafer 2 is cured.

After the above-described reinforcing sheet heating step is carried out, a printing step may be performed to irradiate the area of the reinforcing sheet 6 corresponding to each device with laser light to print an ID mark for identifying the device. This printing step can be carried out by the same laser processing apparatus as the laser processing apparatus 5 shown in Fig. 5 described above. That is, when the printing step is to be performed, the side of the protective tape 3 attached to the surface 2a of the semiconductor wafer 2 is placed on the chuck stage 51 of the laser processing apparatus 5 shown in FIG. Further, the semiconductor wafer 2 is held by the protective tape 3 on the chuck stage 51 by a suction mechanism not shown in the drawing (wafer holding step). As a result, the reinforcing sheet 6 attached to the back surface of the semiconductor wafer 2 held on the chuck stage 51 is on the upper side. In this manner, the chuck stage 51 that sucks and holds the semiconductor wafer 2 through the protective tape 3 can be positioned directly below the image pickup mechanism 53 by a processing transfer mechanism (not shown).

After the chuck table 51 is positioned directly below the camera mechanism 53, The semiconductor wafer 2 on the chuck stage 51 is brought into a state of being positioned at a predetermined coordinate position. In this state, whether or not the grid-shaped dividing line 21 formed on the semiconductor wafer 2 held on the chuck table 51 has been arranged to be aligned in the X direction and the Y direction (calibration step). That is, the semiconductor wafer 2 held by the chuck table 51 is imaged by the imaging unit 53, and image processing such as pattern matching is performed to perform a calibration operation. At this time, although the surface 2a of the semiconductor wafer 2 on which the planned dividing line 21 is formed is located on the lower side, the imaging unit 53 is provided with an infrared illuminating mechanism, an optical system for capturing infrared rays, and can correspond to infrared rays as described above. Since the image sensor (infrared CCD) of the electric signal output is formed by the image sensor (infrared CCD), the division line 21 can be imaged by penetrating from the back surface 2b.

By performing the above-described calibration step, the semiconductor wafer 2 held on the chuck stage 51 can be positioned at a predetermined coordinate position. Next, as shown in FIG. 9, the chuck stage 51 is moved to position the position corresponding to the predetermined device in the reinforcing sheet 6 directly below the concentrator 422, while the pulsed laser light irradiated from the concentrator 422 is irradiated. The condensed spot is positioned near the surface (upper surface) of the reinforcing sheet 6. Further, by irradiating the pulsed laser beam having the absorptive wavelength of the reinforcing sheet 6 emitted from the concentrator 422, the chuck table 51 is moved in the X direction and the Y direction to complement the reinforcing sheet. An ID mark 61 (printing step) for identifying the device is printed on the area corresponding to the predetermined device in 6. This printing step is performed on the areas of the reinforcing sheet 6 corresponding to all the devices.

The processing conditions of the above printing step are set under the following conditions, for example.

Wavelength: 355nm pulsed laser

Repeat frequency: 10kHz

Average output: 1W

Spot point diameter: φ50μm

After performing the above printing step, the wafer supporting step may be performed, and the dicing tape is attached to the cured reinforcing sheet 6 mounted on the back surface of the semiconductor wafer 2, and the outer peripheral portion of the dicing tape is mounted in a ring shape. On the frame. That is, as shown in FIGS. 10(a) and (b), the side of the cured reinforcing sheet 6 attached to the back surface of the semiconductor wafer 2 on which the printing step is applied is attached to cover the inside of the annular frame F. The surface of the dicing tape T of the outer peripheral portion is attached to the opening portion (wafer supporting step). As a result, the protective tape 3 attached to the surface of the semiconductor wafer 2 becomes the upper side. Further, as shown in FIG. 11, the protective tape 3 attached to the surface of the semiconductor wafer 2 can be peeled off (protective member peeling step).

After the wafer supporting step and the protective member peeling step are performed as described above, the dividing step can be performed, an external force is applied to the semiconductor wafer 2, and the semiconductor wafer 2 is divided along the dividing line 21 on which the modified layer 210 is formed. The devices 22 are individually ruptured at the same time along the individual devices 22. This dividing step is carried out using the tape expanding device 8 shown in Fig. 12. The tape expanding device 8 shown in Fig. 12 includes a frame holding mechanism 81 for holding the annular frame F, and a dicing tape T attached to the annular frame F held by the frame holding mechanism 81. The tape expansion mechanism 82, and the pickup chuck 83. The frame holding mechanism 81 is composed of an annular frame holding member 811 and a plurality of jigs 812 which are disposed on the outer periphery of the frame holding member 811 as a fixing mechanism. The top surface of the frame holding member 811 is formed with a mountable ring shape The mounting surface 811a of the frame F is placed on the mounting surface 811a. Further, the annular frame F placed on the mounting surface 811a is fixed to the frame holding member 811 through the jig 812. The frame holding mechanism 81 thus constituted is supported to advance and retreat in the up and down direction by the tape expanding mechanism 82.

The tape expansion mechanism 82 includes an expansion roller 821 disposed inside the annular frame holding member 811. The expansion roller 821 has an inner diameter and an outer diameter which are smaller than the inner diameter of the annular frame F and larger than the outer diameter of the semiconductor wafer 2 attached to the dicing tape T attached to the annular frame F. Further, the expansion drum 821 is provided with a support flange 822 located at the lower end. The tape expansion mechanism 82 in the illustrated embodiment includes a support mechanism 823 that allows the annular frame holding member 811 to advance and retreat in the vertical direction. The support mechanism 823 is composed of a plurality of cylinders 823a disposed on the support flange 822, and is coupled to the bottom surface of the annular frame holding member 811 by a piston rod 823b. The support mechanism 823 composed of the plurality of cylinders 823a can form the annular frame holding member 811 in the vertical direction so that the mounting surface 811a and the upper end of the expansion drum 821 are substantially the same as shown in Fig. 13(a). The reference position of the height is moved between the expanded position below the predetermined amount of the upper end of the expansion drum 821 as shown in Fig. 13 (b).

The dividing step performed by the tape expanding device 8 constructed as described above will be described with reference to FIG. In other words, the annular frame F on which the dicing tape T attached to the reinforcing sheet 6 side of the semiconductor wafer 2 is attached can be placed on the frame holding member constituting the frame holding mechanism 81 as shown in FIG. 13(a). The mounting surface 811a of the 811 is fixed to the frame holding member 811 by a jig 812. On (frame keeping step). At this time, the frame holding member 811 is positioned at the reference position shown in Fig. 13 (a). Next, the plurality of cylinders 823a constituting the tape expansion mechanism 82 as the support mechanism 823 are actuated to lower the annular frame holding member 811 to the expanded position as shown in Fig. 13(b). As a result, since the annular frame F fixed to the mounting surface 811a of the frame holding member 811 is also lowered, the dicing tape T attached to the annular frame F is brought into contact as shown in FIG. 13(b). The upper end edge of the roller 821 is expanded to be expanded (tape expansion step). As a result, the reinforcing sheet 6 attached to the dicing tape T and the semiconductor wafer 2 on which the reinforcing sheet 6 is attached are radially acted upon by tensile force. When the tensile force is applied to the reinforcing sheet 6 and the semiconductor wafer 2 in such a manner that the semiconductor wafer 2 is formed with the reforming layer 210 which becomes the starting point of the fracture along the dividing line 21, it can be along the dividing line. 21 is divided into individual devices 22, and a space (s) can be formed between the individual devices 22, so that tension can be generated on the reinforcing sheets 6 which are solidified by performing the above-described reinforcing sheet heating step. It acts to break along the individual devices 22.

After the above-described dividing step, the pickup chuck 83 is actuated as shown in FIG. 14(a) to suck the device 22 (the reinforcing sheet 6 is attached to the back surface) and peel off from the dicing tape T for picking up. A semiconductor device 22 having a reinforcing sheet 6 that is broken along the outer periphery of the device 22 is mounted on the back surface as shown in Fig. 14 (b) (pickup step). Further, in the pickup step, since the gap S between the individual devices 22 in which the reinforcing sheets 6 are mounted as described above is expanded and expanded, it can be easily performed without being in contact with the adjacent device 22. Pick up. In this manner, the reinforcing sheet 6 mounted on the back surface of the device 22 to be picked up is mounted with the ID mark 61 for identifying the device, so that the device 22 is mounted. It can be confirmed when it comes to each device.

Next, another embodiment of the method of processing a wafer of the present invention will be described.

In this embodiment, after the reinforcing sheet mounting step is performed, and before the reinforcing sheet heating step is performed, a reinforcing sheet cooling step of cooling the reinforcing sheet 6 to reduce the viscosity is performed. This reinforcing sheet cooling step is carried out using the cooling device 9 shown in FIG. The cooling device 9 is a process cartridge 91 in which the upper end is opened, a lid 92 that closes the upper end of the process cartridge 91, and a workpiece mounting table 93 that is placed in the process cartridge 91 and placed on the workpiece, and is disposed. The cold air injection nozzle 94 is formed on the inner surface of the cover 92, and the cold air injection nozzle 94 is connected to a cold air supply mechanism (not shown). When the reinforcing sheet cooling step is performed by the cooling device 9 configured as described above, the lid 92 is opened to place the side of the protective tape 3 attached to the surface of the semiconductor wafer 2 on the workpiece mounting table 93. As a result, the reinforcing sheet 6 attached to the back surface of the semiconductor wafer 2 placed on the workpiece mounting table 93 is on the upper side. In this manner, the side of the protective tape 3 attached to the surface of the semiconductor wafer 2 is placed on the workpiece mounting table 93, and after the upper lid 92 is closed, the cold air supply mechanism not shown in the drawing can be used. The reinforcing sheet 6 is cooled by ejecting cold air from the cold air injection nozzle 94. In the reinforcing sheet cooling step, the viscous sheet 6 can be made less viscous by cooling the reinforcing sheet 6 to -5 to 5 °C.

After the above-described reinforcing sheet cooling step is performed, a protective member peeling step of peeling off the protective tape 3 attached to the surface of the semiconductor wafer 2 can be performed. This protective member peeling step is performed as shown in FIG. 16(a), and the adhesiveness of the semiconductor wafer 2 mounted on the surface of the above-described reinforcing sheet is lowered. The side of the low reinforcing sheet 6 is placed on the chuck table 101 of the peeling device 10. Further, the semiconductor wafer 2 is sucked and held by the chucking station 101 by the reinforcing sheet 6 by an attraction mechanism not shown in the drawing. As a result, the protective tape 3 attached to the surface of the semiconductor wafer 2 held by the nip sheet 6 by the reinforcing sheet 6 is attached to the upper side. In this manner, after the semiconductor wafer 2 is sucked and held by the reinforcing sheet 6 and held on the chuck stage 101, the protective tape 3 attached to the surface of the semiconductor wafer 2 can be peeled off as shown in FIG. 16(b).

After the reinforcing sheet cooling step and the protective member peeling step are performed as described above, the above-described reinforcing sheet heating step, printing step, wafer supporting step, dividing step, and picking step can be performed.

Claims (2)

A wafer processing method is a wafer in which a device is formed by dividing a plurality of predetermined lines on a surface into a grid and forming a device in a plurality of regions divided by the plurality of predetermined lines, and dividing along a dividing line A wafer processing method for forming a device, comprising: a protective member attaching step of attaching a protective member to a surface of the wafer; and a back grinding step of attaching the surface through the protective member attaching step The protective member side of the wafer having the protective member is held on the chuck table of the grinding device, and the back surface of the wafer is ground to form a predetermined thickness; the reforming layer forming step is formed to be predetermined through the back grinding step The protective member side of the thickness of the wafer is held on the chuck table of the laser processing apparatus, and the laser beam having a wavelength penetrating the wafer is positioned from the back side of the wafer to condense the spot inside to follow The dividing line is irradiated, and a modified layer is formed inside the wafer along the dividing line; the reinforcing sheet mounting step is provided with an insulating function on the back surface of the wafer on which the reforming layer forming step is performed a reinforcing sheet; a reinforcing sheet heating step of heating the reinforcing sheet mounted on the back surface of the wafer through the reinforcing sheet mounting step to cure the reinforcing sheet; and a wafer supporting step of attaching the cutting tape to the reinforcing sheet, the reinforcing sheet The sheet is mounted on the back surface of the wafer on which the reinforcing sheet heating step has been applied, and is cured, and the outer peripheral portion of the dicing tape is mounted on the annular frame; and the dividing step is performed to give the wafer supporting step Outside the wafer Force the wafer to be divided into individual devices along the dividing line formed with the modified layer, and the reinforcing sheets are broken along the individual devices. After the reinforcing sheet mounting step is performed, the reinforcing sheet heating is performed. Before the step, the reinforcing sheet cooling step is performed, the reinforcing sheet mounted on the back surface of the wafer is cooled to reduce the viscosity, and the reinforcing sheet side which is subjected to the cooling step of the reinforcing sheet to reduce the viscosity is held on the chuck table. After that, the protective member peeling step is performed to peel off the protective member attached to the wafer surface. The processing method of the wafer according to claim 1, wherein after the reinforcing sheet heating step is performed, a printing step may be performed, and the region corresponding to each device in the reinforcing sheet is irradiated with laser light for printing for identification The ID of the device.