JP6559477B2 - Wafer processing method - Google Patents

Description

  The present invention relates to a wafer processing method.

  In the device manufacturing process, a plurality of devices arranged in a matrix on a wafer and a grid-like division planned line that partitions the plurality of devices are provided. A device chip such as an IC (integrated circuit) or an LSI (large scale integration) is manufactured by dividing the wafer along the division line by the cutting device.

  In order to improve the processing capability of the device, a low dielectric constant insulating film (Low) comprising an inorganic film such as SiOF or BSG (SiOB) and an organic film such as a polymer film such as polyimide or parylene. A method for manufacturing a device from a wafer having a functional layer including a -k film has been put into practical use. The functional layer has a brittle nature. Therefore, there arises a problem that the functional layer is easily separated from the substrate by cutting with the cutting blade of the cutting apparatus. In order to deal with this problem, the functional layer is removed by irradiating a laser beam along the planned dividing line on both sides in the width direction of the planned dividing line and forming two laser processing grooves along the planned dividing line. A processing method has been proposed in which a cutting blade is positioned between the two laser processing grooves and the cutting blade and the wafer are moved relative to each other to cut the wafer along a predetermined division line (see Patent Document 1). .

However, this processing method requires at least two laser beam scans to remove the functional layer, and the processing time is prolonged. Further, depending on the shape of the formed laser processing groove, the cutting blade may be unevenly worn. In addition, it is necessary to provide a protective film on the surface of the wafer in order to prevent adhesion of debris (laser processing waste) generated by laser beam irradiation. Further, a passivation film containing SiO ₂ or SiN is formed on the surface of the functional layer, and when the irradiated laser beam passes through the passivation film and reaches the inside of the functional layer, the energy of the laser beam loses its escape field, The energy will damage the device.

  In order to solve these problems, the present applicant cuts the back surface of the substrate with a cutting blade, forms a cutting groove leaving a part of the substrate that does not reach the functional layer, and forms the cutting groove from the back surface of the substrate. The processing method which removes a functional layer by irradiating a laser beam along the bottom is proposed (refer to patent documents 2).

JP-A-2005-64231 Japanese Patent Application No. 2014-152961

  However, in this processing method, since most of the wafer (substrate) in the thickness direction is cut with a cutting blade in the cutting device, the wafer is transported to the laser processing device, so that the wafer may be damaged during transport. is there.

  This invention is made | formed in view of the above, Comprising: It aims at providing the processing method of the wafer which can suppress the damage at the time of conveyance of the wafer after cutting.

In order to solve the above-described problems and achieve the object, the present invention provides a functional layer laminated on the surface of a substrate, a plurality of division lines formed in a lattice shape, and a plurality of division lines divided into the division lines. A method of processing a wafer in which a device is formed in an area, and after performing a protective tape attaching step of attaching a protective tape that is cured by an external stimulus to the surface of a functional layer, and the protective tape attaching step A protective tape curing step for curing the protective tape by applying an external stimulus to the protective tape; a first holding step for holding the wafer via the protective tape on a chuck table of a cutting apparatus including a cutting means; after performing the first holding step, from the rear surface side of the substrate along the dividing lines and cutting only the substrate with the cutting blade of the cutting means, leaving a remaining portion that does not lead to functional layer A cutting groove forming step for forming a groove, a second holding step for holding the wafer via the protective tape on the chuck table of a processing apparatus after performing the protective tape curing step and the cutting groove forming step; After the second holding step is performed, the remaining portion is processed by non-machining, and the wafer is divided into device chips. The cured protective tape is formed by cutting only the substrate and cutting the substrate. Provided is a wafer processing method for suppressing breakage during conveyance of a wafer in which grooves are formed.

  In the wafer processing method, the external stimulus is preferably ultraviolet light.

  According to the wafer processing method of the present invention, by using a protective tape that is cured by an external stimulus, damage during conveyance of the wafer after cutting is suppressed.

FIG. 1 is a diagram illustrating a wafer processing system according to the first embodiment. FIG. 2 is a perspective view showing the cutting apparatus according to the first embodiment. FIG. 3 is a perspective view showing the laser processing apparatus according to the first embodiment. FIG. 4 is a perspective view showing the wafer according to the first embodiment. FIG. 5 is a cross-sectional view illustrating a main part of the wafer according to the first embodiment. FIG. 6 is a flowchart illustrating the wafer processing method according to the first embodiment. FIG. 7 is a diagram illustrating a protective tape attaching step according to the first embodiment. FIG. 8 is a diagram illustrating a protective tape attaching step according to the first embodiment. FIG. 9 is a diagram illustrating a protective tape curing step according to the first embodiment. FIG. 10 is a diagram illustrating a first holding step according to the first embodiment. FIG. 11 is a diagram illustrating a first holding step according to the first embodiment. FIG. 12 is a diagram illustrating an operation of the height measuring instrument according to the first embodiment. FIG. 13 is a diagram illustrating a table stored in the storage device according to the first embodiment. FIG. 14 is a diagram illustrating a cutting groove forming step according to the first embodiment. FIG. 15 is a diagram illustrating a cutting groove forming step according to the first embodiment. FIG. 16 is a diagram illustrating a cutting groove forming step according to the first embodiment. FIG. 17 is a diagram illustrating a cutting groove forming step according to the first embodiment. FIG. 18 is a diagram illustrating division steps according to the first embodiment. FIG. 19 is a diagram illustrating division steps according to the first embodiment. FIG. 20 is a diagram illustrating division steps according to the first embodiment. FIG. 21 is a diagram illustrating division steps according to the first embodiment. FIG. 22 is a diagram illustrating division steps according to the second embodiment. FIG. 23 is a diagram illustrating division steps according to the second embodiment. FIG. 24 is a diagram illustrating division steps according to the third embodiment. FIG. 25 is a diagram illustrating division steps according to the third embodiment. FIG. 26 is a diagram illustrating division steps according to the third embodiment. FIG. 27 is a diagram illustrating a protective tape curing step according to the fourth embodiment. FIG. 28 is a diagram illustrating a protective tape curing step according to the fifth embodiment.

  Hereinafter, embodiments according to the present invention will be described with reference to the drawings, but the present invention is not limited thereto. The components of the embodiments described below can be combined as appropriate. Some components may not be used.

  In the following description, an XYZ orthogonal coordinate system is set, and the positional relationship of each part will be described with reference to this XYZ orthogonal coordinate system. One direction in the horizontal plane is defined as the X-axis direction, a direction orthogonal to the X-axis direction in the horizontal plane is defined as the Y-axis direction, and a direction orthogonal to each of the X-axis direction and the Y-axis direction is defined as the Z-axis direction. An XY plane including the X axis and the Y axis is parallel to the horizontal plane. The Z-axis direction orthogonal to the XY plane is the vertical direction.

[Embodiment 1]
FIG. 1 is a diagram schematically illustrating an example of a processing system 1 for a wafer 200 according to the first embodiment. The processing system 1 divides the wafer 200 into a plurality of device chips. As shown in FIG. 1, the processing system 1 includes a cutting device 2 for cutting the wafer 200, a processing device 3 for processing the wafer 200 by non-machining, and the wafer 200 between the cutting device 2 and the processing device 3. And a conveying device 4 for conveying. The cutting apparatus 2 includes a chuck table 10 that holds a wafer 200 and a cutting unit 20 that cuts the wafer 200. In the first embodiment, the processing apparatus 3 is a laser processing apparatus. The processing apparatus 3 includes a chuck table 130 that holds the wafer 200 and laser beam irradiation means 140 that irradiates the wafer 200 with a laser beam. The transport device 4 transports the wafer 200 while sucking and holding it.

  FIG. 2 is a perspective view showing an example of the cutting device 2. The cutting device 2 cuts the wafer 200. As shown in FIG. 2, the cutting device 2 includes a base 5, a portal frame 6 supported by the base 5, a chuck table 10 that holds the wafer 200, a cutting means 20 that cuts the wafer 200, A machining feed means 30 for moving the chuck table 10; an index feed means 40 and a cutting feed means 50 for moving the cutting means 20; an X-axis direction position detection means 60 for detecting the position of the chuck table 10 in the X-axis direction; Y-axis direction position detecting means 70 for detecting the position of the cutting means 20 in the Y-axis direction and Z-axis direction position detecting means 80 for detecting the position of the cutting means 20 in the Z-axis direction are provided. The X-axis direction is a direction in which the wafer 200 held on the chuck table 10 is processed and fed. The Y-axis direction is a direction in which the cutting means 20 is indexed and fed to the wafer 200 held on the chuck table 10.

  The chuck table 10 holds the wafer 200 in a detachable manner. The chuck table 10 is supported by the base 5. The chuck table 10 has a circular holding surface 11 that holds the wafer 200. The holding surface 11 is parallel to the XY plane. The chuck table 10 can be rotated around a rotation axis orthogonal to the center of the holding surface 11 by a rotating means including an actuator. A plurality of suction ports connected to a vacuum suction source including a vacuum pump are provided on the holding surface 11. The wafer 200 is sucked and held on the chuck table 10 by operating the vacuum suction source with the wafer 200 placed on the holding surface 11. The wafer 200 is released from the chuck table 10 by stopping the operation of the vacuum suction source.

  The cutting means 20 cuts the wafer 200 held on the chuck table 10. The cutting means 20 is supported by the portal frame 6 via the index feed means 40 and the cut feed means 50. The portal frame 6 is supported by the base 5.

  The cutting means 20 includes a cutting blade 21, a spindle 22, and a housing 23. The cutting blade 21 includes an annular cutting grindstone mounted on the spindle 22. The cutting blade 21 is detachably attached to the tip of the spindle 22. The housing 23 has a drive source such as a rotary motor, and supports the spindle 22 rotatably about a rotation axis parallel to the Y axis. When the spindle 22 is rotated by the operation of the drive source, the wafer 200 is cut by the cutting blade 21.

  The machining feed means 30 moves the chuck table 10 in the X-axis direction. The chuck table 10 and the cutting means 20 are relatively moved in the X-axis direction by the processing feed means 30. The processing feed means 30 includes a ball screw mechanism. The processing feed means 30 includes a pair of guide rails 31 supported by the base 5 and extending in the X-axis direction, a screw shaft 32 disposed in parallel to the guide rails 31, and a ball around the screw shaft 32 via a ball. It has the nut arrange | positioned, the X-axis movement base 33 fixed to a nut, and the pulse motor which generate | occur | produces the motive power for rotating the screw shaft 32. The X-axis moving base 33 is guided by the guide rail 31 in the X-axis direction. The machining feed means 30 rotates the screw shaft 32 with a pulse motor to move the X-axis movement base 33 in the X-axis direction, thereby moving the chuck table 10 supported by the X-axis movement base 33 in the X-axis direction. Move to.

  The index feeding means 40 moves the cutting means 20 in the Y-axis direction. The cutting means 20 is supported by the index feed means 40 via the cut feed means 50. By the index feeding means 40, the chuck table 10 and the cutting means 20 are relatively moved in the Y-axis direction. The index feeding means 40 includes a ball screw mechanism. The index feed means 40 includes a pair of guide rails 41 supported by the portal frame 6 and extending in the Y-axis direction, a screw shaft 42 arranged in parallel to the guide rail 41, and a ball around the screw shaft 42. And a Y-axis moving base 43 fixed to the nut, and a pulse motor that generates power for rotating the screw shaft 42. The Y-axis moving base 43 is guided by the guide rail 41 in the Y-axis direction. The index feed means 40 rotates the screw shaft 42 by a pulse motor to move the Y-axis movement base 43 in the Y-axis direction, thereby changing the cutting feed means 50 supported by the Y-axis movement base 43 to the Y-axis. Move in the direction. When the cutting feed means 50 moves in the Y-axis direction, the cutting step 20 supported by the cutting feed means 50 moves in the Y-axis direction together with the cutting feed means 50.

  The cutting feed means 50 moves the cutting means 20 in the Z-axis direction. By the cutting feed means 50, the chuck table 10 and the cutting means 20 are relatively moved in the Z-axis direction. The cutting feed means 50 includes a ball screw mechanism. The cutting feed means 50 is supported by the Y-axis moving base 43 and extends in the Z-axis direction, a screw shaft arranged parallel to the guide rail, and a ball around the screw shaft via a ball And a Z-axis moving base 51 fixed to the nut, and a pulse motor 52 that generates power for rotating the screw shaft. The Z-axis moving base 51 is guided in the Z-axis direction by the guide rail of the cutting feed means 50. The cutting feed means 50 rotates the screw shaft by the pulse motor 52 and moves the Z-axis movement base 51 in the Z-axis direction, thereby moving the cutting means 20 supported by the Z-axis movement base 51 in the Z-axis direction. Move to.

  The X-axis direction position detecting means 60 detects the position of the chuck table 10 in the X-axis direction. The X-axis direction position detecting means 60 includes a linear scale 61 supported by the base 5 and extending in the X-axis direction along the guide rail 31, and an X-axis along the linear scale 61 supported by the X-axis moving base 33. It has a read head 62 that moves together with the moving base 33. The reading head 62 detects the scale of the linear scale 61 via the optical system and outputs a pulse signal.

  The Y-axis direction position detection means 70 detects the position of the cutting means 20 in the Y-axis direction. The Y-axis direction position detecting means 70 is supported by the portal frame 6 and extends along the guide rail 41 in the Y-axis direction, and supported by the Y-axis moving base 43 and along the linear scale 71. A read head 72 that moves together with the shaft moving base 43 is provided. The read head 72 detects the scale of the linear scale 71 via the optical system and outputs a pulse signal.

  The Z-axis direction position detection unit 80 detects the position of the cutting unit 20 in the Z-axis direction. The Z-axis direction position detection means 80 includes a linear scale 81 supported by the Y-axis movement base 43 and extending in the Z-axis direction, and a Z-axis movement base along the linear scale 81 supported by the Z-axis movement base 51. And a read head 82 that moves together with 51. The reading head 82 detects the scale of the linear scale 81 via the optical system and outputs a pulse signal.

  Further, the cutting apparatus 2 includes a measuring unit 90 that measures the height (position in the Z-axis direction) of the interface 230 between the substrate 201 and the functional layer 202 of the wafer 200, and a Y-axis direction feeding unit 100 that moves the measuring unit 90. And a Z-axis direction feed means 110 and a control means 120 for controlling the cutting device 2.

  The measuring unit 90 is supported by the portal frame 6 via the Y-axis direction feeding unit 100 and the Z-axis direction feeding unit 110. The measuring unit 90 includes a height measuring device 91 that measures the height of the interface 230 using reflected light reflected by the interface 230 between the substrate 201 and the functional layer 202. The height measuring device 91 detects the height of the interface 230 between the substrate 201 and the functional layer 202 using an existing method such as a spectral interference method or a confocal method.

  The Y-axis direction feeding unit 100 moves the measuring unit 90 in the Y-axis direction. The measuring unit 90 is supported by the Y-axis direction feeding unit 100 via the Z-axis direction feeding unit 110. The chuck table 10 and the measuring unit 90 are relatively moved in the Y-axis direction by the Y-axis direction feeding unit 100. The Y-axis direction feeding means 100 includes a ball screw mechanism. The Y-axis direction feeding means 100 includes a pair of guide rails 101 supported by the portal frame 6 and extending in the Y-axis direction, a screw shaft 102 disposed in parallel with the guide rail 101, and a ball around the screw shaft 102. , A Y-axis moving base 103 fixed to the nut, and a pulse motor that generates power for rotating the screw shaft 102. The Y-axis moving base 103 is guided in the Y-axis direction by the guide rail 101. The Y-axis direction feed means 100 is a Z-axis direction feed means supported by the Y-axis movement base 103 by rotating the screw shaft 102 by a pulse motor and moving the Y-axis movement base 103 in the Y-axis direction. 110 is moved in the Y-axis direction. As the Z-axis direction feeding means 110 moves in the Y-axis direction, the measuring means 90 supported by the Z-axis direction feeding means 110 moves in the Y-axis direction together with the Z-axis direction feeding means 110.

  The Z-axis direction feeding unit 110 moves the measuring unit 90 in the Z-axis direction. The chuck table 10 and the measuring unit 90 are relatively moved in the Z-axis direction by the Z-axis direction feeding unit 110. The Z-axis direction feeding means 110 includes a ball screw mechanism. The Z-axis direction feeding means 110 includes a pair of guide rails supported by the Y-axis moving base 103 and extending in the Z-axis direction, a screw shaft arranged in parallel with the guide rails, and balls around the screw shaft. And a Z-axis moving base 111 fixed to the nut, and a pulse motor 112 that generates power for rotating the screw shaft. The Z-axis moving base 111 is guided in the Z-axis direction by the guide rail of the Z-axis direction feeding means 110. The Z-axis direction feeding means 110 rotates the screw shaft by the pulse motor 112 to move the Z-axis movement base 111 in the Z-axis direction, thereby moving the measuring means 90 supported by the Z-axis movement base 111 to the Z-axis direction. Move in the axial direction.

  The control means 120 includes a computer system. The control unit 120 includes an arithmetic processing device having a microprocessor such as a CPU (central processing unit), a storage device having a memory such as a ROM (read only memory) or a RAM (random access memory), and an input / output interface device. And have. The arithmetic processing device of the control means 120 performs arithmetic processing in accordance with a computer program stored in the storage device, and outputs a control signal for controlling the cutting device 2 via the input / output interface device.

  The control means 120 controls the components of the cutting device 2. The control unit 120 is connected to a drive circuit that drives the pulse motors of the machining feed unit 30, the index feed unit 40, and the cutting feed unit 50, and controls the drive circuit to determine the position of the chuck table 10 in the X-axis direction, cutting. The position of the means 20 in the Y-axis direction and the position of the cutting means 20 in the Z-axis direction are determined. The control unit 120 is connected to a drive circuit that drives the pulse motors of the Y-axis direction feed unit 100 and the Z-axis direction feed unit 110, and controls the drive circuit to control the position of the measurement unit 90 in the Y-axis direction, and The position of the measuring means 90 in the Z-axis direction is determined.

  FIG. 3 is a diagram illustrating an example of the laser processing apparatus 3. The laser processing apparatus 3 includes a chuck table 130 that holds the wafer 200, a laser beam irradiation unit 140 that irradiates the wafer 200 held on the chuck table 130 with a laser beam, and an imaging unit that images the wafer 200 held on the chuck table 130. 150.

  The chuck table 130 holds the wafer 200 in a detachable manner. The chuck table 130 has a circular holding surface 131 that holds the wafer 200. The holding surface 131 is parallel to the XY plane. A plurality of suction ports connected to a vacuum suction source including a vacuum pump are provided on the holding surface 131. The wafer 200 is sucked and held on the chuck table 130 by operating the vacuum suction source with the wafer 200 placed on the holding surface 131. The wafer 200 is released from the chuck table 130 by stopping the operation of the vacuum suction source.

  The laser processing apparatus 3 includes a processing feed unit that moves the chuck table 130 in the X-axis direction and an index feed unit that moves the chuck table 130 in the Y-axis direction. The wafer 200 held on the chuck table 130 is moved in the X-axis direction and the Y-axis direction by the processing feed means and the index feed means.

  The laser beam application unit 140 includes a casing 141 that houses the pulse laser beam oscillation unit, and a condenser 142 that is attached to the tip of the casing 141 and collects the pulse laser beam output from the pulse laser beam oscillation unit. The pulse laser beam oscillation means includes a pulse laser beam oscillator and a repetition frequency setting means. Further, the laser beam irradiation unit 140 includes a condensing point position adjusting unit for adjusting the condensing point position of the pulse laser beam condensed by the condenser 142.

  The imaging unit 150 is supported by the casing 141. The imaging unit 150 includes an optical system, an illuminating unit that illuminates the wafer 200 disposed in the visual field region of the optical system, and an imaging element that acquires an optical image of the wafer 2 illuminated with the illumination light beam through the optical system. Have The image signal of the wafer acquired by the image sensor is output to the control means of the laser processing apparatus 3.

  FIG. 4 is a perspective view showing the wafer 200. FIG. 5 is a cross-sectional view showing the main part of the wafer 200. As shown in FIGS. 4 and 5, the wafer 200 includes a substrate 201 and a functional layer 202 provided on the substrate 201. The substrate 201 is a silicon substrate. Note that the substrate 201 may contain gallium arsenide, or sapphire or SiC. The substrate 201 is substantially disk-shaped, and has a front surface 201A and a back surface 201B facing the opposite direction of the front surface 201A. A notch 203 is provided on the substrate 201.

The functional layer 202 is provided on the surface 201 </ b> A of the substrate 201. The functional layer 202 is a layer in which an insulating film and a functional film that forms a circuit are stacked. The insulating film that forms the functional layer 202 is a low dielectric constant insulating film (Low) composed of an inorganic film such as SiOF or BSG (SiOB) and an organic film that is a polymer film such as polyimide or parylene. -K film). A passivation film containing SiO ₂ or SiN is formed on the surface 202A of the functional layer 202.

  In the functional layer 202 laminated on the surface 201A of the substrate 201, a plurality of division lines 204 formed in a lattice shape and a device 205 are formed in a plurality of regions partitioned by the division lines 204. A device chip such as an IC (integrated circuit) or an LSI (Large Scale Integration) is manufactured from the device 204 by dividing the wafer 200 along the division line 204.

  Next, a wafer processing method will be described. FIG. 6 is a flowchart illustrating a method for processing the wafer 200 according to the first embodiment. As shown in FIG. 6, the processing method of the wafer 200 includes a protective tape attaching step (SP1) for attaching a protective tape 300 that is cured by an external stimulus to the surface of the functional layer 202, and a protective tape attaching step (SP1). ), A protective tape curing step (SP2) for applying an external stimulus to the protective tape 300 to cure the protective tape 300, and the chuck table 10 of the cutting apparatus 2 including the cutting means 20 via the protective tape 300. After performing the first holding step (SP3) for holding the wafer 200 and the first holding step (SP1), cutting is performed by the cutting blade 21 of the cutting means 20 along the division line 204 from the back surface 201B side of the substrate 201. A cutting groove forming step (SP4) for forming the cutting groove 220 leaving the remaining portion 210 that does not reach the functional layer 202, and protection After performing the loop curing step (SP2) and the cutting groove forming step (SP4), a second holding step (SP5) for holding the wafer 200 on the chuck table 130 of the processing apparatus 3 via the protective tape 300, and a second After performing the holding step (SP5), the remaining portion 210 is processed by non-machining, and the wafer 200 is divided into device chips (SP6).

  The protective tape attaching step (SP1) will be described. 7 and 8 are diagrams showing the protective tape attaching step. As shown in FIG. 7, after the functional layer 202 of the wafer 200 and the protective tape 300 face each other, the protective tape 300 is attached to the surface 202 </ b> A of the functional layer 202 of the wafer 200. The device 205 of the functional layer 202 is protected by the protective tape 300. As shown in FIG. 8, the size of the outer shape of the protective tape 300 and the size of the outer shape of the wafer 200 are substantially equal. The protective tape 300 includes a base layer and a paste layer laminated on the base layer. The protective tape 300 is attached to the functional layer 202 of the wafer 200 by the adhesive layer, and the entire surface 202A of the functional layer 202 is protected. Covered with tape 300.

  The adhesive layer of the protective tape 300 is cured by an external stimulus. The external stimulus is ultraviolet light. The protective tape 300 is cured by being irradiated with ultraviolet rays. The adhesive layer of the protective tape 300 is formed of an ultraviolet curable resin.

  Next, the protective tape curing step (SP2) will be described. The protective tape curing step is performed after the protective tape attaching step. FIG. 9 is a diagram showing a protective tape curing step. As shown in FIG. 9, ultraviolet rays are irradiated to the protective tape 300 by the ultraviolet irradiation device 160. The ultraviolet irradiation device 160 is a chuck table 161 that holds the wafer 200 to which the protective tape 300 is attached, and an external stimulus applying unit that irradiates the protective tape 300 with ultraviolet rays while the wafer 200 is held on the chuck table 161. Certain ultraviolet irradiation means 162.

  The chuck table 161 has a holding surface that detachably holds the wafer 200. The holding surface of the chuck table 161 and the back surface 201B of the substrate 201 of the wafer 200 face each other. The chuck table 161 holds the wafer 200 so that the ultraviolet irradiation means 162 and the protective tape 300 face each other.

  The ultraviolet irradiation means 162 has a light source 163 that can emit ultraviolet rays. The ultraviolet irradiation means 162 has a plurality of light sources 163 aligned. The light source 163 includes a UV (ultraviolet) lamp. The light source 163 is, for example, a low-pressure mercury lamp, and can irradiate the protective tape 300 with at least one of ultraviolet light having a wavelength of 184 nm, ultraviolet light having a wavelength of 254 nm, and ultraviolet light having a wavelength of 365 nm. The light source 163 may be an excimer UV lamp capable of emitting ultraviolet light having a wavelength of 172 nm, an LED (light emitting diode) light source, or a high-pressure mercury lamp.

  The protective tape 300 is irradiated with ultraviolet rays while being attached to the wafer 200. The protective tape 300 is cured by being irradiated with ultraviolet rays. The ultraviolet irradiation unit 162 irradiates the protective tape 300 attached to the wafer 200 held on the chuck table 161 with ultraviolet rays. The protective tape 300 is cured while being in contact with the functional layer 202 of the wafer 200.

  Next, the first holding step (SP3) will be described. The first holding step is performed after the protective tape curing step. 10 and 11 are diagrams showing the first holding step. As shown in FIG. 10, the wafer 200 is held on the chuck table 10 of the cutting apparatus 2 via the protective tape 300. The holding surface 11 of the chuck table 10 and the protective tape 300 face each other. The chuck table 10 holds the wafer 200 via the protective tape 300. The chuck table 10 holds the protective tape 300 so that the back surface 201B of the substrate 201 of the wafer 200 faces upward.

  After the wafer 200 is held on the chuck table 10 of the cutting apparatus 2 via the protective tape 300, the control unit 120 uses the measuring unit 90 to height the interface 230 between the substrate 201 and the functional layer 202 of the wafer 200. A height recording step for measuring (position in the Z-axis direction) is performed. In the height recording step, the control unit 120 holds the wafer 200 on the chuck table 10 via the protective tape 300 and then performs an alignment process. Next, the control unit 120 moves the height measuring device 91 in the Y-axis direction and the Z-axis direction, and moves the chuck table 10 in the X-axis direction, thereby positioning the height measuring device 91 on the planned division line 204. For example, the control unit 120 positions the height measuring device 91 at the measurement start position of the scheduled division line 204 located at the extreme end in the Y-axis direction. The back surface 201B of the substrate 201 of the wafer 200 held on the chuck table 10 and the height measuring device 91 face each other.

  Next, as shown in FIGS. 10 and 11, the control means 120 emits a laser beam LB1 having a wavelength that passes through the substrate 201 from the height measuring device 91 in the Z-axis direction, and in the division target line 204 to be measured. The chuck table 10 is moved in the X-axis direction to the measurement end position.

  FIG. 12 is a diagram for explaining the height measured by the height measuring device 91. As shown in FIG. 12, the height measuring device 91 determines the height H1 of the interface 230 between the functional layer 202 and the substrate 201 corresponding to the division line 204 from the back surface 201B side of the wafer 200 held on the chuck table 10. To detect. For example, the height measuring device 91 first obtains the distance H2 to the interface 230 based on the reflected light reflected from the interface 230 between the functional layer 202 and the substrate 201. Next, the height measuring device 91 subtracts the distance H 2 from the holding surface 11 of the chuck table 10 to the interface 230 from the distance H 3 from the holding surface 11 of the chuck table 10 to the height measuring device 91, and The height H1 is detected. The height measuring device 91 outputs the detected height H1 to the control means 120.

  FIG. 13 is a diagram illustrating an example of the table T stored in the storage device of the control unit 120. As shown in FIG. 13, the control means 120 determines the height H1 of the interface 230 between the functional layer 202 and the substrate 201, the X coordinate of the planned division line 204, and the remaining portion 210 of the substrate 201 that does not reach the functional layer 202. A table T in which the Z coordinate indicating the height H4 obtained by adding the thickness h to be formed on the substrate 201 to the height H1 is recorded in the storage device for each division line 204. The control means 120 records a table T in which the X coordinate, the height H1, and the Z coordinate are associated with all the division planned lines 204. The X coordinate of the planned division line 204 to be recorded is the same X coordinate as the X coordinate at which the cutting blade 21 is positioned in the cutting groove forming step (SP4). The Z coordinate of the planned division line 204 is the same Z coordinate as the Z coordinate at which the lower end of the cutting blade 21 is positioned. Note that the thickness h for forming the remaining portion 210 can be changed as appropriate by the operator setting the value of the thickness h in the cutting device 2.

  Next, the cutting groove forming step (SP4) will be described. The cutting groove forming step is performed after the first holding step and the height recording step. After the height recording step is completed, the measuring means 90 is retracted from the chuck table 10.

  In the cutting groove forming step, the control means 120 cuts with the cutting blade 12 of the cutting means 20 along the planned dividing line 204 from the back surface 201B side of the substrate 201, leaving a remaining portion 210 that does not reach the functional layer 202. 220 is formed on the substrate 201.

  FIG. 14, FIG. 15, FIG. 16, and FIG. 17 are diagrams showing a cutting groove forming step. As shown in FIGS. 14 and 15, the control unit 120 positions the cutting blade 21 at the start position for processing the division line 204 to be processed from the back surface 201 </ b> B side of the substrate 201. And the control means 120 reads the table T corresponding to the division | segmentation scheduled line 204 of a process target with reference to a memory | storage device. As shown in FIGS. 16 and 17, the control unit 120 moves the wafer 200 held on the chuck table 10 in the X-axis direction, and based on the X coordinate and the Z coordinate of the scheduled division line 204 indicated by the table T. The cutting blade 21 is moved in the Z-axis direction to form a cutting groove 220 that leaves a remaining portion 210 having a uniform thickness h that does not reach the functional layer 202. At this time, the control unit 120 determines the X coordinate of the chuck table 10 based on the pulse signal output from the reading head 62 of the X-axis direction position detection unit 60, that is, the division line of the wafer 200 held on the chuck table 10. The X coordinate of 204 is acquired. Further, the control unit 120 acquires the Z coordinate of the cutting blade 21 based on the pulse signal output from the reading head 82 of the Z-axis direction position detection unit 80. The control means 120 controls to form the cutting groove 220 having the remaining portion 210 for all the division lines 204.

  Next, the second holding step (SP5) will be described. The second holding step is performed after the cutting groove forming step. After the cutting groove forming step is completed, the wafer 200 held on the chuck table 10 of the cutting device 2 is unloaded from the chuck table 10 together with the protective tape 300 by the transport device 4.

  The transfer device 4 sucks and holds the back surface 201 </ b> B of the substrate 201 of the wafer 200 and transfers the wafer 200 and the protective tape 300. The hardened protective tape 300 suppresses breakage during transportation of the wafer 200 on which the cutting grooves 220 are formed. By forming the cutting groove 220 on the substrate 200, the wafer 200 is easily damaged. However, since the cured protective tape 300 is adhered to the wafer 200, the wafer 200 is reinforced by the protective tape 300. Is done. Therefore, breakage of the wafer 200 is suppressed in the transfer from the cutting device 2 to the processing device 3 by the transfer device 4.

  The transfer device 4 loads the held wafer 200 onto the chuck table 130 of the processing device 3. The transfer device 4 transfers the wafer 200 to which the protective tape 300 is attached to the chuck table 130 of the processing device 3 so that the protective tape 300 attached to the wafer 200 and the holding surface of the chuck table 130 face each other. Carry in. The wafer 200 is held on the chuck table 130 of the processing apparatus 3 via the protective tape 300.

  Next, the division step (SP6) will be described. The dividing step is performed after the second holding step. The dividing step is performed in the processing apparatus 3.

  In the dividing step, the remaining portion 210 is processed by non-machining by the processing device 3. The processing apparatus 3 is a laser processing apparatus, and irradiates a laser beam to divide the wafer 200 on which the cutting groove 220 having the remaining portion 210 is formed.

  18, 19, 20, and 21 are diagrams showing the division step. The processing apparatus 3 sucks and holds the wafer 200 with the chuck table 130 via the protective tape 300, and irradiates the remaining portion 210 of the cutting groove 220 with the laser beam LB 2 along the division line 204 by the laser beam irradiation means 140 to cut the cutting groove. 240 is formed, and the remaining portion 210 and the functional layer 202 are divided (ablation processing). For example, the ablation processing is performed by matching the condensing point of the laser beam LB <b> 2 having an absorptive wavelength near the surface of the remaining portion 210. The processing apparatus 3 divides the remaining portion 210 and the functional layer 202 by irradiating the remaining portion 210 of the cutting groove 220 with the laser beam LB2 along all the division lines 204. By dividing the remaining portion 210 and the functional layer 202, the wafer 200 is divided into a plurality of device chips.

  As described above, according to the processing method of the wafer 200 according to the first embodiment, the protective tape 300 that is cured by an external stimulus is attached to the surface 202A of the functional layer 202 of the wafer 200, and the protective tape 300 is cured. Thereafter, a cutting groove forming step for forming the cutting groove 220 on the wafer 200 by the cutting apparatus 2 and the wafer 200 on which the cutting groove 220 is formed are transferred to the processing apparatus 3 in a state of being adhered to the protective tape 300 and then the remaining portion. The dividing step of processing 210 is performed. The wafer 200 after the cutting groove 220 is formed is easily damaged. Since the wafer 200 is reinforced by the cured protective tape 300, the wafer 200 can be transported while suppressing damage to the wafer 200. Therefore, a reduction in device chip productivity and a reduction in the quality of the manufactured device chip are suppressed.

  Further, the remaining portion 210 and the functional layer 202 are divided by irradiation with the laser beam LB2, which is non-machining, and are not divided by machining using a cutting blade, so that the cutting blade is misaligned or falls, or the cutting blade has uneven wear. Occurrence is suppressed.

  Further, since the laser beam LB2 is irradiated from the back surface 201B side of the wafer 200, debris is prevented from adhering to the surface of the wafer 200.

  Further, since the bottom of the cutting groove 220 is irradiated with the laser beam LB2, the energy of the laser beam LB2 can be reduced, and residual thermal strain in the wafer 200 is suppressed. In addition, a decrease in the bending strength of the device 205 is suppressed.

  Further, after the cutting groove 220 is formed from the back surface 201B side of the substrate 201, the wafer 200 is divided by irradiating the cutting groove 220 with the laser beam LB2. Since the irradiation with the laser beam LB2 only needs to be performed once (one pass), the wafer 200 is divided with high work efficiency. In addition, since the width of the planned division line 204 can be reduced, the area of the planned division line 204 can be reduced, and the area of the device 205 formed on the surface of the wafer 200 can be increased.

  In the first embodiment, when the protective tape 300 is irradiated with ultraviolet rays, the cutting device 2 may be provided with ultraviolet irradiation means 162, and ultraviolet rays are irradiated within the cutting device 2, or the wafer 200 is cut into the cutting device 2. The protective tape 300 adhered to the wafer 200 may be irradiated with ultraviolet rays while being held on the chuck table 10.

[Embodiment 2]
Next, a method for processing the wafer 200 according to the second embodiment will be described. 22 and 23 are cross-sectional views illustrating steps for dividing the wafer 200 by plasma etching according to the second embodiment.

  After the cutting groove 220 having the remaining portion 210 along all the planned dividing lines 204 is formed on the back surface 201B of the wafer 200, the remaining cutting groove 220 remains on the back surface 201B of the wafer 200 as shown in FIG. A resist film 250 is formed on the portion excluding the portion 210. For example, the resist film 250 is applied to the entire back surface 201B of the wafer 200, the resist film 250 is irradiated with light through a predetermined mask pattern, and the wafer 200 is immersed in a developer, whereby the resist film of the remaining portion 210 is exposed. 250 is removed. Next, plasma etching is performed in a plasma chamber atmosphere. Thereby, as shown in FIG. 23, the remaining portion 210 of the cutting groove 220 and the functional layer 202 corresponding to the remaining portion 210 are removed.

  As described above, the wafer 200 may be divided by removing the remaining portion 210 and the functional layer 202 of the cutting groove 220 by plasma etching without using a laser processing apparatus as the processing apparatus 3.

  Note that the resist film 250 may be applied to the back surface 201 </ b> B of the wafer 200 before the cutting process, and the resist film 250 may be removed along the planned division line 204 by a cutting process for forming the cutting groove 220.

[Embodiment 3]
Next, a method for processing the wafer 200 according to the third embodiment will be described. 24, 25, and 26 are cross-sectional views illustrating steps of dividing the wafer 200 by the modified layer according to the third embodiment.

  After the cutting groove 220 having the remaining portion 210 along all the planned dividing lines 204 is formed on the back surface 201B of the wafer 200, the laser beam irradiation means 140 applies a laser beam to the remaining portion 210 of the cutting groove 220 along the planned dividing line 204. LB3 is irradiated from the back surface 201B side of the wafer 200. The laser beam LB3 is a laser beam having a wavelength that is transmissive to the substrate 201. The condensing point of the laser beam LB3 is positioned at the center of the remaining portion 210 in the thickness direction. The modified layer 260 is formed on the substrate 201 by irradiation with the laser beam LB3.

  The strength of the portion where the modified layer 260 is provided decreases, and the modified layer 260 serves as a starting point for fracture. When an external force is applied to the wafer 200 by a tape expand or the like, the remaining portion 210 and the functional layer 202 are broken along the division line 204. Note that the protective tape 300 attached to the surface of the functional layer 202 is an expandable tape having elasticity.

  As described above, the modified layer 260 serving as the starting point of breakage is formed by irradiation with the laser beam LB3 without performing the ablation process by the processing apparatus 3 which is a laser processing apparatus, and the remaining portion 210 of the cutting groove 220 and The wafer 200 may be divided by breaking the functional layer 202.

[Embodiment 4]
Next, a method for processing the wafer 200 according to the fourth embodiment will be described. FIG. 27 is a diagram illustrating a protective tape curing step according to the fourth embodiment. A protective tape 400 that is cured by an external stimulus is attached to the surface of the functional layer 202 of the wafer 200. In the fourth embodiment, the external stimulus is heat (warming). The protective tape 400 is cured by being heated. The protective tape 400 is a sheet-like member formed of a thermosetting resin. As shown in FIG. 27, the protective tape 400 is heated by the heating device 170. The heating device 170 is a chuck table 171 that holds the wafer 200 to which the protective tape 400 is adhered, and an external stimulus applying unit that heats the protective tape 400 while the wafer 200 is held by the chuck table 171. Heating means 172. The heating means 172 includes, for example, a heater device provided with a heating wire.

  The chuck table 171 has a holding surface for holding the wafer 200. The holding surface of the chuck table 171 and the back surface 201B of the substrate 201 of the wafer 200 face each other. The chuck table 171 holds the wafer 200 so that the heating means 172 and the protective tape 400 face each other. By being heated by the heating means 172, the protective tape 400 is cured while being in contact with the functional layer 202.

[Embodiment 5]
Next, a method for processing the wafer 200 according to the fifth embodiment will be described. In each of the above-described embodiments, the first holding step (SP3) is performed after the protective tape curing step (SP2). After the first holding step (SP3), a protective tape curing step (SP2) may be performed.

  FIG. 28 is a diagram illustrating a protective tape curing step according to the fifth embodiment. As shown in FIG. 28, the wafer 200 is held on the chuck table 10B of the cutting apparatus 2 via the protective tape 300 (first holding step). After the wafer 200 is held on the chuck table 10B via the protective tape 300, a protective tape curing step is performed.

  The chuck table 10B is formed of a material that is transparent to ultraviolet rays. The ultraviolet irradiation means 162B irradiates the protective tape 300 facing the holding surface of the chuck table 10B through the chuck table 10B with ultraviolet rays. The ultraviolet rays emitted from the ultraviolet irradiation means 162B pass through the chuck table 10B, and are then applied to the protective tape 300 held on the chuck table 10B. As a result, the protective tape 300 is cured (protective tape curing step).

  After the protective tape 300 is cured, a cutting groove forming step (SP4) is performed.

  Before the protective tape 300 is cured, a cutting groove forming step is performed. After the cutting groove 220 is formed on the wafer 200, a protective tape curing step of irradiating the protective tape 300 with ultraviolet rays via the chuck table 10B is performed. May be implemented.

  In the fifth embodiment, the protective tape 400 may be cured by attaching a thermosetting protective tape 400 to the wafer 200 and heating the chuck table 10B.

  In each of the above-described embodiments, the functional layer 202 includes not only a low-k film but also all films having functions such as a passivation film, a metal film, and an optical device layer.

DESCRIPTION OF SYMBOLS 1 Processing system 2 Cutting apparatus 3 Laser processing apparatus 4 Conveyance apparatus 5 Base 6 Gate type frame 10 Chuck table 11 Holding surface 20 Cutting means 21 Cutting blade 22 Spindle 23 Housing 30 Processing feed means 31 Guide rail 32 Screw shaft 33 X-axis movement Base 40 Index feed means 41 Guide rail 42 Screw shaft 43 Y-axis movement base 50 Cut feed means 51 Z-axis movement base 52 Pulse motor 60 X-axis direction position detection means 61 Linear scale 62 Reading head 70 Y-axis direction position detection Means 71 Linear scale 72 Reading head 80 Z-axis direction position detecting means 81 Linear scale 82 Reading head 90 Measuring means 91 Height measuring device 100 Y-axis direction feeding means 101 Guide rail 102 Screw shaft 103 Y-axis moving base 110 Z-axis direction Feeding means 111 Z-axis shift Moving base 112 Pulse motor 120 Control means 130 Chuck table 140 Laser beam irradiation means 150 Imaging means 160 Ultraviolet irradiation apparatus 161 Chuck table 162 Ultraviolet irradiation means 170 Heating apparatus 171 Chuck table 172 Heating means 163 Light source 200 Wafer 201 Substrate 201A Surface 201B Back surface 202 Functional layer 202A Front surface 203 Notch 204 Line to be divided 205 Device 210 Remaining portion 220 Cutting groove 230 Interface 240 Cutting groove 250 Resist film 260 Modified layer 300 Protective tape 400 Protective tape

Claims (2)

In the functional layer laminated on the surface of the substrate, a wafer processing method in which devices are formed in a plurality of division lines formed in a lattice shape and a plurality of areas partitioned by the division lines,
A protective tape attaching step for attaching a protective tape that is cured by an external stimulus to the surface of the functional layer;
A protective tape curing step of applying an external stimulus to the protective tape and curing the protective tape after performing the protective tape application step;
A first holding step of holding a wafer via the protective tape on a chuck table of a cutting apparatus provided with a cutting means;
After carrying out the first holding step, only the substrate is cut with a cutting blade of the cutting means along the planned dividing line from the back side of the substrate to form a cutting groove leaving a remaining portion that does not reach the functional layer. A cutting groove forming step;
A second holding step of holding the wafer via the protective tape on a chuck table of a processing apparatus after performing the protective tape curing step and the cutting groove forming step;
After performing the second holding step, processing the remaining part by non-machining, and dividing the wafer into device chips,
A method for processing a wafer, wherein the cured protective tape suppresses damage during transportation of a wafer in which only the substrate is cut and the cut groove is formed.   2. The wafer processing method according to claim 1, wherein the external stimulus is ultraviolet rays.

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