JP2014165436A - Processing method of wafer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a processing method of a wafer which allows for breaking of an adhesive film for die bonding, applied to the rear surface of a device having a plurality of areas sectioned by a plurality of streets formed like a lattice on the surface, along the streets.SOLUTION: A processing method of a wafer includes a cutting groove formation step for forming cutting grooves 210, having a depth determined by subtracting a predetermined residual thickness from the finish thickness of a device 22, along streets 21 from the surface side of a wafer 2, a protective member sticking step for sticking a protective member to the surface of the wafer, a rear surface grinding step for grinding the rear surface of the wafer down to the bottom of the cutting groove while leaving a predetermined residual thickness, a wafer support step for sticking an adhesive film 6 and a dicing tape T to the rear surface of the wafer and supporting the outer peripheral part by an annular frame, and a laser processing step for breaking the residual part 211 of the wafer having a predetermined residual thickness and the adhesive film, by irradiating the bottom of the cutting groove with a laser beam from the surface side of the wafer.

Description

  The present invention divides a wafer in which devices are formed into a plurality of regions partitioned by streets formed in a lattice shape on the surface into individual devices along the streets, and die bonding that is mounted on the back surface of each device The present invention relates to a wafer processing method in which an adhesive film can be broken along the outer periphery of a device.

  For example, in a semiconductor device manufacturing process, devices such as IC and LSI are formed in a plurality of regions partitioned by division lines (streets) formed in a lattice shape on the surface of a semiconductor wafer having a substantially disk shape, Individual semiconductor devices are manufactured by dividing each region in which the devices are formed along the streets. A dicing apparatus is generally used as a dividing apparatus for dividing a semiconductor wafer, and the dicing apparatus cuts the semiconductor wafer along the street with a cutting blade having a thickness of about 20 μm. The semiconductor devices divided in this way are packaged and widely used in electric devices such as mobile phones and personal computers.

  Individually divided semiconductor devices have an adhesive film for die bonding called a die attach film (DAF) with a thickness of 20 to 40 μm formed of polyimide resin, epoxy resin, acrylic resin fat, etc. on the back surface thereof. It is mounted and bonded by heating to a die bonding frame that supports the semiconductor device through this adhesive film. As a method of attaching the adhesive film for die bonding to the back surface of the semiconductor device, the adhesive film is attached to the back surface of the semiconductor wafer, the semiconductor wafer is attached to the dicing tape through the adhesive film, and then the semiconductor wafer By cutting along with the adhesive film with a cutting blade along the street formed on the front surface, a semiconductor device having the adhesive film mounted on the back surface is formed. (For example, refer to Patent Document 1.)

  However, according to the method disclosed in Japanese Patent Application Laid-Open No. 2000-182959, when the adhesive film is cut together with the semiconductor wafer by the cutting blade and divided into individual semiconductor devices, the back surface of the semiconductor device is chipped or bonded. There is a problem in that wrinkle-like burrs are generated in the film and cause breakage during wire bonding.

  In recent years, electric devices such as mobile phones and personal computers are required to be lighter and smaller, and thinner semiconductor devices are required. As a technique for dividing a semiconductor device thinner, a dividing technique called a so-called first dicing method has been put into practical use. In this tip dicing method, a cutting groove having a predetermined depth (a depth corresponding to the finished thickness of the semiconductor device) is formed along the street from the surface of the semiconductor wafer, and then the semiconductor wafer having the cutting groove formed on the surface is formed. In this technique, the back surface of the semiconductor device is ground and a cutting groove is exposed on the back surface to divide the semiconductor device into individual semiconductor devices. The thickness of the semiconductor device can be reduced to 50 μm or less.

  However, when the semiconductor wafer is divided into individual semiconductor devices by the pre-dicing method, a back surface of the semiconductor wafer is ground by forming a cutting groove having a predetermined depth along the street from the surface of the semiconductor wafer. Therefore, the die bonding adhesive film cannot be mounted on the back surface of the semiconductor wafer in advance. Therefore, when bonding to the die bonding frame that supports the semiconductor device by the first dicing method, the bonding agent must be inserted between the semiconductor device and the die bonding frame, and the bonding operation is performed smoothly. There is a problem that can not be.

  In order to solve such problems, an adhesive film for die bonding is attached to the back surface of the wafer divided into individual semiconductor devices by the prior dicing method, and the semiconductor device is attached to the dicing tape via the adhesive film. After that, the portion of the adhesive film exposed in the gap between the semiconductor devices is irradiated with a laser beam through the gap from the surface side of the semiconductor device, and the portion of the adhesive film exposed in the gap is removed. A method for manufacturing a semiconductor device has been proposed. (For example, see Patent Document 2.)

  However, when the semiconductor wafer is divided into individual semiconductor devices along the street by the tip dicing method, the semiconductor wafer is divided individually by the force acting at the time of grinding even though the protective member is adhered to the surface of the semiconductor wafer. The semiconductor device is slightly displaced. Therefore, the dividing grooves formed along the streets of the semiconductor wafer meander instead of a straight line. For this reason, when irradiating a laser beam to an adhesive film through a division | segmentation groove | channel, it is difficult to melt | fuse only an adhesive film, without irradiating the laser beam to the surface of a semiconductor device.

  In order to solve such problems, the semiconductor wafer is divided into individual semiconductor devices along the street by the dicing method, and after attaching the adhesive film for die bonding on the back surface, the laser beam is applied to the adhesive film through the dividing groove. Patent Document 3 below describes a processing method in which, when irradiating, a coordinate value of a meandering dividing groove is detected to create a processing line map, and a laser beam is irradiated according to the processing line map.

JP 2000-182959 A JP 2002-118081 A JP 2007-7668 A

  Thus, in the processing method described in Patent Document 3, the coordinate value of the meandering divided grooves formed on the wafer is detected to create a processing line map, and a laser beam is emitted along the meandering divided grooves. There is a problem that the control is complicated because it must be irradiated.

  The present invention has been made in view of the above facts, and the main technical problem thereof is a wafer processing method in which an adhesive film for die bonding mounted on the back surface of a device can be broken along the outer periphery of the device. Is to provide.

In order to solve the above main technical problem, according to the present invention, a wafer in which devices are formed in a plurality of regions partitioned by a plurality of streets formed in a lattice shape on the surface is divided into individual devices along the streets. And a wafer processing method in which an adhesive film is attached to the back of each device,
A cutting groove forming step of forming a cutting groove having a depth obtained by subtracting a predetermined remaining thickness from the finished thickness of the device along the street from the surface side of the wafer;
A protective member attaching step for attaching a protective member to the surface of the wafer on which the cutting groove forming step has been performed;
A back surface grinding step of grinding the back surface of the wafer on which the protective member attaching step has been performed, and grinding to leave the predetermined remaining thickness to the bottom surface of the cutting groove;
The adhesive film is attached to the back surface of the wafer subjected to the back grinding process, and a dicing tape is attached to the adhesive film side, and the outer peripheral portion of the dicing tape is supported by an annular frame, and the protection is attached to the wafer surface. A wafer support step for peeling the member;
A laser processing step of irradiating a laser beam from the surface side of the wafer on which the wafer support step has been performed to the bottom of the cutting groove to break the remaining portion of the wafer having the predetermined remaining thickness and the adhesive film.
A method for processing a wafer is provided.

The thickness of the remaining portion of the wafer is set to 5 to 10 μm from the bottom of the cutting groove.
In the laser processing step, a laser beam having a wavelength that absorbs the wafer and the adhesive film is irradiated from the surface side of the substrate along the bottom of the cutting groove to form a laser processing groove in the remaining portion of the wafer and the adhesive film. To do.
Further, the laser processing step irradiates a laser beam having a wavelength that is transparent to the wafer and the adhesive film with a focusing point positioned at the remaining portion of the wafer and an intermediate portion of the adhesive film, and the remaining portion of the wafer and the adhesive film. A modified layer is formed on the substrate.
Further, the wafer processing method includes a device separation step of expanding the dicing tape to which the wafer is adhered after the laser processing step and separating the wafer into individual devices along the street.

  In the wafer processing method according to the present invention, in the cutting groove forming step, the cutting groove formed to a depth obtained by subtracting a predetermined remaining thickness from the finished thickness of the device along the street from the surface side of the wafer is displayed in the back grinding step. Since it is not taken out and is not divided into individual devices, it does not meander and is linear, so there is no need to detect coordinate values and create a machining line map, and complicated control of the laser beam irradiation position becomes unnecessary.

The perspective view which shows the semiconductor wafer processed by the processing method of the wafer by this invention. Explanatory drawing of the cutting groove formation process in the processing method of the wafer by this invention. Explanatory drawing of the protection member sticking process in the processing method of the wafer by this invention. Explanatory drawing of the back surface grinding process in the processing method of the wafer by this invention. Explanatory drawing of the wafer support process in the processing method of the wafer by this invention. Explanatory drawing which shows 2nd Embodiment of the wafer support process in the processing method of the wafer by this invention. The principal part perspective view of the laser processing apparatus for implementing the laser processing process in the processing method of the wafer by this invention. Explanatory drawing which implements 1st Embodiment of the laser processing process in the processing method of the wafer by this invention. Explanatory drawing which implements 2nd Embodiment of the laser processing process in the processing method of the wafer by this invention. The perspective view of the device separation apparatus for implementing the device separation process in the processing method of the wafer by this invention. Explanatory drawing of the device isolation | separation process in the processing method of the wafer by this invention.

  Preferred embodiments of a wafer laser processing method according to the present invention will be described below in more detail with reference to the accompanying drawings.

  FIG. 1 is a perspective view of a semiconductor wafer as a wafer. The semiconductor wafer 2 shown in FIG. 1 is made of, for example, a silicon wafer having a thickness of 200 μm, and a plurality of streets 21 are formed in a lattice shape on the surface 2a. On the surface 2 a of the semiconductor wafer 2, devices 22 such as IC and LSI are formed in a plurality of regions partitioned by a plurality of streets 21 formed in a lattice shape. A procedure for dividing the semiconductor wafer 2 into individual semiconductor devices by the prior dicing method will be described.

  In order to divide the semiconductor wafer 2 into individual semiconductor devices by the pre-dicing method, first, a predetermined depth (a predetermined remaining thickness is subtracted from the finished thickness of each device) along the street 21 formed on the surface 2a of the semiconductor wafer 2. The depth of the cut groove is formed (cutting groove forming step). In the illustrated embodiment, this cutting groove forming step is performed using a cutting device 3 shown in FIG. The cutting device 3 shown in FIG. 2A is held by the chuck table 31 that holds the workpiece, the cutting means 32 that cuts the workpiece held by the chuck table 31, and the chuck table 31. An image pickup means 33 for picking up an image of the workpiece is provided. The chuck table 31 is configured to suck and hold a workpiece, and is moved in a cutting feed direction indicated by an arrow X in FIG. 2A by an unillustrated cutting feed mechanism, and an unillustrated indexing feed mechanism. Can be moved in the index feed direction indicated by the arrow Y.

  The cutting means 32 includes a spindle housing 321 arranged substantially horizontally, a rotary spindle 322 rotatably supported by the spindle housing 321, and a cutting blade 323 mounted on the tip of the rotary spindle 322. The rotary spindle 322 is rotated in the direction indicated by the arrow 322a by a servo motor (not shown) disposed in the spindle housing 321. The thickness of the cutting blade 323 is set to 40 μm in the illustrated embodiment. The imaging means 33 is attached to the tip of the spindle housing 321 and illuminates the workpiece, an optical system that captures an area illuminated by the illumination means, and an image captured by the optical system. An image pickup device (CCD) or the like for picking up images is provided, and the picked up image signal is sent to a control means (not shown).

  In order to perform the cutting groove forming process using the cutting device 3 described above, the back surface 2b side of the semiconductor wafer 2 is placed on the chuck table 31 as shown in FIG. By operating, the semiconductor wafer 2 is held on the chuck table 31. Therefore, the surface 2a of the semiconductor wafer 2 held on the chuck table 31 is on the upper side. In this way, the chuck table 31 that sucks and holds the semiconductor wafer 2 is positioned directly below the imaging means 33 by a cutting feed mechanism (not shown).

  When the chuck table 31 is positioned immediately below the image pickup means 33, an alignment operation for detecting a cutting region in which a cutting groove is to be formed along the street 21 of the semiconductor wafer 2 is executed by the image pickup means 33 and a control means (not shown). That is, the imaging unit 33 and a control unit (not shown) execute image processing such as pattern matching for aligning the street 21 formed in a predetermined direction of the semiconductor wafer 2 and the cutting blade 323, and cutting region Alignment is performed (alignment process). In addition, the alignment of the cutting area is similarly performed on the street 21 formed on the semiconductor wafer 2 and extending at right angles to the predetermined direction.

  When the alignment for detecting the cutting area of the semiconductor wafer 2 held on the chuck table 31 is performed as described above, the chuck table 31 holding the semiconductor wafer 2 is moved to the cutting start position of the cutting area. . Then, the cutting blade 323 is moved downward while rotating in the direction indicated by the arrow 322a in FIG. The cutting feed position is such that the outer peripheral edge of the cutting blade 323 is a depth position (for example, 40 μm) obtained by subtracting a predetermined remaining thickness (for example, 10 μm) from the finished thickness (for example, 50 μm) of the device from the surface of the semiconductor wafer 2. Is set. When the cutting blade 323 is cut and fed in this way, the chuck table 31 is cut and fed in the direction indicated by the arrow X in FIG. As shown in (b), a cutting groove 210 having a depth (for example, 40 μm) obtained by subtracting a predetermined remaining thickness from the finished thickness of the device (for example, 50 μm) along the street 21 and having a width of 40 μm is formed (cutting). Groove forming step).

In addition, the said cutting groove formation process is performed on the following process conditions, for example.
Cutting blade: outer diameter 52mm, thickness 40μm
Cutting blade rotation speed: 30000 rpm
Cutting feed rate: 50 mm / sec

  The above-described cutting groove forming step is performed on the areas corresponding to all the streets 21 formed on the semiconductor wafer 2.

  If the cutting groove 210 having a predetermined depth is formed along the street 21 on the surface 2a of the semiconductor wafer 2 by performing the above-described cutting groove forming step, the semiconductor wafer is formed as shown in FIGS. 3 (a) and 3 (b). The protective tape 4 is stuck on the surface 2a of 2 (the surface on which the device 22 is formed) (protective member sticking step).

  Next, a back surface grinding process is performed in which the back surface 2b of the semiconductor wafer 2 to which the protective tape 4 is adhered is ground and ground to a bottom surface of the cutting groove 210 while leaving a predetermined remaining thickness. This back grinding process is performed using a grinding apparatus 5 shown in FIG. 4A includes a chuck table 51 that holds a workpiece, and a grinding unit 53 that includes a grinding wheel 52 for grinding the workpiece held on the chuck table 51. It has. In order to carry out the back surface grinding process using this grinding apparatus 5, the semiconductor wafer 2 is placed on the chuck table 51 by placing the protective tape 4 side of the semiconductor wafer 2 on the chuck table 51 and operating a suction means (not shown). Hold on 51. Therefore, the back surface 2b of the semiconductor wafer 2 held on the chuck table 51 is on the upper side. If the semiconductor wafer 2 is held on the chuck table 51 in this way, the grinding wheel 52 of the grinding means 53 is moved in the direction indicated by the arrow 52a while the chuck table 51 is rotated in the direction indicated by the arrow 51a, for example, at 300 rpm. For example, while rotating at 6000 rpm, the back surface 2b of the semiconductor wafer 2 is contacted and ground, and the remaining portion 211 having a predetermined remaining thickness (for example, 10 μm) is formed to the bottom surface of the cutting groove 210 as shown in FIG. Leave and grind. The thickness of the remaining portion 211 is desirably 5 to 10 μm in the illustrated embodiment.

  If the back grinding process described above is performed, an adhesive film for die bonding is mounted on the back surface 2b of the semiconductor wafer 2, and a dicing tape is attached to the adhesive film side, and the outer periphery of the dicing tape is supported by an annular frame. Then, a wafer support step for peeling the protective member attached to the surface of the semiconductor wafer 2 is performed. In the first embodiment in the wafer support process, the adhesive film 6 is mounted on the back surface 2b of the semiconductor wafer 2 as shown in FIGS. 5A and 5B (adhesive film mounting process). At this time, the adhesive film 6 is pressed and attached to the back surface 2b of the semiconductor wafer 2 while being heated at a temperature of 80 to 200 ° C. The adhesive film 6 is formed of an epoxy resin and is made of a film material having a thickness of 20 μm. When the adhesive film 6 is attached to the back surface 2b of the semiconductor wafer 2 in this way, the adhesive film 6 side of the semiconductor wafer 2 to which the adhesive film 6 is attached is connected to the annular frame F as shown in FIG. Affix to the dicing tape T that can be stretched. Accordingly, the protective tape 4 attached to the surface 2a of the semiconductor wafer 2 is on the upper side. Then, the protective tape 4 attached to the surface 2a of the semiconductor wafer 2 is peeled off. In the embodiment shown in FIGS. 5A to 5C, the adhesive film 6 side of the semiconductor wafer 2 having the adhesive film 6 attached to the dicing tape T attached to the annular frame F is attached. Although an example is shown, the dicing tape T may be attached to the side of the adhesive film 6 of the semiconductor wafer 2 to which the adhesive film 6 is attached, and the outer peripheral portion of the dicing tape T may be attached to the annular frame F at the same time.

Another embodiment of the wafer support process described above will be described with reference to FIG.
The embodiment shown in FIG. 6 uses a dicing tape with an adhesive film in which an adhesive film 6 is previously attached to the surface of the dicing tape T. That is, as shown in FIGS. 6A and 6B, the adhesive film 6 adhered to the surface of the dicing tape T with the outer peripheral portion attached so as to cover the inner opening of the annular frame F is attached to the semiconductor. The back surface 2b of the wafer 2 is attached. At this time, the adhesive film 6 is pressed and attached to the back surface 2b of the semiconductor wafer 2 while being heated at a temperature of 80 to 200 ° C. The dicing tape T is made of a polyolefin sheet having a thickness of 95 μm in the illustrated embodiment. When a dicing tape with an adhesive film is used in this way, the semiconductor with the adhesive film 6 attached by attaching the back surface 2b of the semiconductor wafer 2 to the adhesive film 6 adhered to the surface of the dicing tape T. The wafer 2 is supported by a dicing tape T mounted on an annular frame F. Then, as shown in FIG. 6B, the protective tape 4 adhered to the surface 2a of the semiconductor wafer 2 is peeled off. In the embodiment shown in FIGS. 6A and 6B, the back surface 2b of the semiconductor wafer 2 is attached to the adhesive film 6 adhered to the surface of the dicing tape T having the outer peripheral portion attached to the annular frame F. However, the adhesive film 6 adhered to the dicing tape T may be attached to the back surface 2b of the semiconductor wafer 2 and the outer periphery of the dicing tape T may be attached to the annular frame F at the same time.

  If the wafer support step is performed as described above, a laser processing step is performed in which the laser beam is irradiated from the surface 2a side of the semiconductor wafer 2 along the bottom of the cutting groove 210 to break the remaining portion 211 and the adhesive film 6. . This laser processing step is performed using a laser processing apparatus 7 shown in FIG. The laser processing apparatus 7 shown in FIG. 7 has a chuck table 71 that holds a workpiece, laser beam irradiation means 72 that irradiates the workpiece held on the chuck table 71 with a laser beam, and a chuck table 71 that holds the workpiece. An image pickup means 73 for picking up the processed workpiece is provided. The chuck table 71 is configured to suck and hold the workpiece. The chuck table 71 is moved in a processing feed direction indicated by an arrow X in FIG. 7 by a processing feed means (not shown), and in FIG. 7 by an index feed means (not shown). It can be moved in the index feed direction indicated by the arrow Y.

  The laser beam application means 72 includes a cylindrical casing 721 arranged substantially horizontally. In the casing 721, pulse laser beam oscillating means including a pulse laser beam oscillator and repetition frequency setting means (not shown) are arranged. A condenser 722 for condensing the pulse laser beam oscillated from the pulse laser beam oscillating means is attached to the tip of the casing 721. The laser beam irradiating unit 72 includes a condensing point position adjusting unit (not shown) for adjusting the condensing point position of the pulse laser beam collected by the condenser 722.

  The image pickup means 73 attached to the tip of the casing 721 constituting the laser beam irradiation means 72 includes an illumination means for illuminating the workpiece, an optical system for capturing an area illuminated by the illumination means, and the optical system. An image pickup device (CCD) or the like for picking up the captured image is provided, and the picked-up image signal is sent to a control means (not shown).

1st Embodiment of the laser processing process which irradiates a laser beam along the bottom of the cutting groove 210 from the surface 2a side of the semiconductor wafer 2 using the laser processing apparatus 7 mentioned above, and fracture | ruptures the remaining part 211 and the adhesive film 6 Will be described with reference to FIGS.
First, the dicing tape T side on which the semiconductor wafer 2 subjected to the wafer support process described above is attached is placed on the chuck table 71 of the laser processing apparatus 7 shown in FIG. Then, by operating a suction means (not shown), the semiconductor wafer 2 is held on the chuck table 71 via the dicing tape T (wafer holding step). Therefore, the surface 2a of the semiconductor wafer 2 held on the chuck table 71 is on the upper side. In FIG. 7, the annular frame F to which the dicing tape T is attached is not shown, but the annular frame F is held by appropriate frame holding means provided on the chuck table 71. In this manner, the chuck table 71 that sucks and holds the semiconductor wafer 2 is positioned directly below the imaging unit 73 by a processing feed unit (not shown).

  When the chuck table 71 is positioned directly below the image pickup means 73, an alignment operation for detecting a processing region to be laser processed on the semiconductor wafer 2 is executed by the image pickup means 73 and a control means (not shown). That is, the imaging unit 73 and the control unit (not shown) are configured to cut the cutting groove 210 formed in a predetermined direction along the street 21 formed on the surface 2 a of the semiconductor wafer 2 and the laser beam that irradiates the laser beam along the cutting groove 210. Image processing such as pattern matching for performing alignment with the condenser 722 of the irradiation unit 72 is performed, and alignment of the laser beam irradiation position is performed (alignment process). In addition, alignment of the laser beam irradiation position is similarly performed on the cutting groove 210 formed in the semiconductor wafer 2 in a direction orthogonal to the predetermined direction. Note that the cutting grooves 210 formed along the streets 21 on the surface 2a of the semiconductor wafer 2 are not exposed in the back grinding step and are not divided into individual devices. It is not necessary to create a processing line map by detecting this.

  When the alignment step described above is performed, the chuck table 71 is moved to the laser beam irradiation area where the condenser 722 of the laser beam irradiation means 72 for irradiating the laser beam is located as shown in FIG. It is positioned directly below the optical device 722. At this time, as shown in FIG. 8A, the semiconductor wafer 2 is positioned so that one end of the cutting groove 210 (the left end in FIG. 8A) is located directly below the condenser 722. Then, as shown in FIG. 8C, the condensing point P of the pulse laser beam LB irradiated from the condenser 722 is matched with the vicinity of the bottom surface of the cutting groove 210. Next, the chuck table 71 is indicated by an arrow X1 in FIG. 8A while irradiating the semiconductor wafer 2 and the adhesive film 6 with a pulsed laser beam having an absorptive wavelength from the condenser 722 of the laser beam irradiation means 72. Move in the direction at a predetermined machining feed rate. Then, as shown in FIG. 8B, when the other end of the cutting groove 210 (the right end in FIG. 8B) reaches a position directly below the condenser 722, the irradiation of the pulse laser beam is stopped and the chuck table is stopped. The movement of 71 is stopped (laser machining groove forming step).

  Next, the chuck table 71 is moved in the direction perpendicular to the paper surface (index feed direction) by the interval of the cutting grooves 210 (corresponding to the interval of the streets 21). Then, while irradiating a pulse laser beam from the condenser 722 of the laser beam irradiation means 72, the chuck table 71 is moved in the direction indicated by the arrow X2 in FIG. When the position shown in FIG. 2 is reached, the irradiation of the pulse laser beam is stopped and the movement of the chuck table 71 is stopped.

  By performing the laser processing groove forming step described above, the laser processing groove 220 is formed in the remaining portion 211 and the adhesive film 6 remaining in the back surface grinding step on the semiconductor wafer 2 as shown in FIG. It is formed. As a result, the remaining portion 211 and the adhesive film 6 remaining in the back grinding step are broken by the laser processing groove 220. Then, the laser processing groove forming step described above is performed along all the streets 21 formed in the semiconductor wafer 2. Thus, when the laser processing groove forming step is performed, the cutting grooves 210 formed along the streets 21 on the front surface 2a of the semiconductor wafer 2 are not exposed in the back grinding step and are divided into individual devices. Since it is not meandering and is linear, complicated control of the laser beam irradiation position becomes unnecessary.

In addition, the said laser processing groove | channel formation process is performed on the following processing conditions, for example.
Laser beam wavelength: 355 nm
Repetition frequency: 200 kHz
Output: 8W
Condensing spot diameter: φ10μm
Processing feed rate: 300 mm / sec

Next, referring to FIG. 9, a second embodiment of the laser processing step of irradiating a laser beam along the bottom of the cutting groove 210 from the surface 2a side of the semiconductor wafer 2 to break the remaining portion 211 and the adhesive film 6 will be described. I will explain. In addition, 2nd Embodiment of a laser processing process can be implemented using the laser processing apparatus substantially the same as the said laser processing apparatus 7. FIG. Therefore, in the second embodiment shown in FIG. 9, the same members as those of the laser processing apparatus 7 will be described with the same reference numerals.
Also in the second embodiment shown in FIG. 8, the wafer holding step and the alignment step are performed in the same manner as in the first embodiment shown in FIGS.

  When the alignment step described above is performed, the chuck table 71 is moved to the laser beam irradiation region where the condenser 722 of the laser beam irradiation means 72 for irradiating the laser beam is located as shown in FIG. It is positioned directly below the optical device 722. At this time, as shown in FIG. 9A, the semiconductor wafer 2 is positioned such that one end of the cutting groove 210 (left end in FIG. 9A) is located directly below the condenser 722. Then, as shown in FIG. 9 (c), the condensing point P of the pulse laser beam LB irradiated from the condenser 722 is positioned at the intermediate part between the remaining part 211 and the adhesive film 6. Next, the chuck table 71 is indicated by an arrow X1 in FIG. 9A while irradiating a pulse laser beam having a wavelength that is transmissive to the semiconductor wafer 2 and the adhesive film 6 from the condenser 722 of the laser beam irradiation means 72. Move in the direction at a predetermined machining feed rate. Then, as shown in FIG. 9B, when the other end of the cutting groove 210 (the right end in FIG. 9B) reaches a position immediately below the condenser 722, the irradiation of the pulse laser beam is stopped and the chuck table is stopped. The movement of 71 is stopped (modified layer forming step).

  Next, the chuck table 71 is moved in the direction perpendicular to the paper surface (index feed direction) by the interval of the cutting grooves 210 (corresponding to the interval of the streets 21). Then, while irradiating a pulse laser beam from the condenser 722 of the laser beam irradiation means 72, the chuck table 71 is moved in a direction indicated by an arrow X2 in FIG. When the position shown in FIG. 2 is reached, the irradiation of the pulse laser beam is stopped and the movement of the chuck table 71 is stopped.

  By performing the above-described modified layer forming step, as shown in FIG. 9D, the remaining portion 211 and the adhesive film 6 remaining on the semiconductor wafer 2 in the back surface grinding step along the cutting groove 210 as shown in FIG. Thus, the modified layer 230 is formed. The modified layer 230 is easily broken in a melted and resolidified state. Then, the modified layer forming step described above is performed along all the streets 21 formed on the semiconductor wafer 2. Even when this modified layer forming step is performed, the cutting grooves 210 formed along the streets 21 on the surface 2a of the semiconductor wafer 2 are not exposed in the back grinding step and are not divided into individual devices. Since it is linear without meandering, complicated control of the laser beam irradiation position becomes unnecessary.

In addition, the said modified layer formation process is performed on the following process conditions, for example.
Laser beam wavelength: 1064 nm
Repetition frequency: 80 kHz
Output: 0.2W
Condensing spot diameter: φ1μm
Processing feed rate: 180 mm / sec

  If the laser processing step (laser processing groove forming step or modified layer forming step) described above is carried out, the dicing tape T to which the semiconductor wafer 2 is adhered is expanded and the wafer is moved along the street 21 to individual devices. A device separation step is performed to separate the device. This device separation step is performed using a device separation apparatus 8 shown in FIG. The device separating apparatus 8 shown in FIG. 10 includes a frame holding means 81 for holding the annular frame F, and a tape extending means for expanding the dicing tape T attached to the annular frame F held by the frame holding means 81. 82 and a pickup collet 83. The frame holding means 81 includes an annular frame holding member 811 and a plurality of clamps 812 as fixing means disposed on the outer periphery of the frame holding member 811. An upper surface of the frame holding member 811 forms a mounting surface 811a on which the annular frame F is placed, and the annular frame F is placed on the mounting surface 811a. The annular frame F placed on the placement surface 811 a is fixed to the frame holding member 811 by a clamp 812. The frame holding means 81 configured as described above is supported by the tape expanding means 82 so as to be able to advance and retreat in the vertical direction.

  The tape expansion means 82 includes an expansion drum 821 disposed inside the annular frame holding member 811. The expansion drum 821 has an inner diameter and an outer diameter that 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. The expansion drum 821 includes a support flange 822 at the lower end. The tape expansion means 82 in the illustrated embodiment includes support means 823 that can advance and retract the annular frame holding member 811 in the vertical direction. The support means 823 includes a plurality of air cylinders 823 a arranged on the support flange 822, and the piston rod 823 b is connected to the lower surface of the annular frame holding member 811. In this way, the support means 823 including the plurality of air cylinders 823a is configured such that the annular frame holding member 811 and the mounting surface 811a are substantially at the same height as the upper end of the expansion drum 821, as shown in FIG. Then, as shown in FIG. 11 (b), it is moved up and down between the extended positions below the upper end of the expansion drum 821 by a predetermined amount.

  A device separation process performed using the device separation apparatus 8 configured as described above will be described with reference to FIG. That is, the annular frame F on which the dicing tape T to which the semiconductor wafer 2 is attached is attached to the mounting surface 811a of the frame holding member 811 constituting the frame holding means 81 as shown in FIG. It is placed on and fixed to the frame holding member 811 by the clamp 812 (frame holding step). At this time, the frame holding member 811 is positioned at the reference position shown in FIG. Next, the plurality of air cylinders 823a as the supporting means 823 constituting the tape extending means 82 are operated to lower the annular frame holding member 811 to the extended position shown in FIG. Accordingly, since the annular frame F fixed on the mounting surface 811a of the frame holding member 811 is also lowered, the dicing tape T attached to the annular frame F is an expansion drum as shown in FIG. Expansion is performed in contact with the upper edge of 821 (tape expansion process). As a result, since a tensile force acts radially on the semiconductor wafer 2 adhered to the dicing tape T, the semiconductor wafer 2 is separated into individual devices 22 and a space S is formed between the devices. Further, when a radial tensile force acts on the semiconductor wafer 2 adhered to the dicing tape T, the modification formed on the remaining portion 211 and the adhesive film 6 of the semiconductor wafer 2 along the cutting groove 210 (and therefore the street 21). The material layer 230 is broken, and the semiconductor wafer 2 and the adhesive film 6 are separated into the individual devices 22 and a space S is formed between the devices.

  Next, as shown in FIG. 11 (c), the pickup collet 83 is operated to adsorb the device 22 having the adhesive film 6 attached to the back surface, peeled off from the dicing tape T, and picked up. Transport to the bonding process. In the pickup process, since the gap S between the individual devices 22 stuck to the dicing tape T is widened as described above, the pickup can be easily performed without contacting the adjacent devices 22. it can.

2: Semiconductor wafer 21: Street 22: Device 210: Cutting groove 220: Laser processing groove 230: Modified layer 3: Cutting device 31: Chuck table of cutting device 32: Cutting means 33: Imaging means 4: Protection tape 5: Grinding Device 51: Chuck table of grinding device 52: Grinding wheel 6: Adhesive film 7: Laser processing device 71: Chuck table of laser processing device 72: Laser beam irradiation means 722: Concentrator 8: Device separation device 81: Frame holding means 82 : Tape expansion means 83: Pickup collet F: Ring frame T: Dicing tape

Next, referring to FIG. 9, a second embodiment of the laser processing step of irradiating a laser beam along the bottom of the cutting groove 210 from the surface 2a side of the semiconductor wafer 2 to break the remaining portion 211 and the adhesive film 6 will be described. I will explain. In addition, 2nd Embodiment of a laser processing process can be implemented using the laser processing apparatus substantially the same as the said laser processing apparatus 7. FIG. Therefore, in the second embodiment shown in FIG. 9, the same members as those of the laser processing apparatus 7 will be described with the same reference numerals.
Also in the second embodiment shown in FIG. 9 , the wafer holding step and the alignment step are performed in the same manner as in the first embodiment shown in FIGS.

Claims (5)

A wafer in which devices are formed in a plurality of regions partitioned by a plurality of streets formed in a lattice pattern on the surface is divided into individual devices along the streets, and an adhesive film is attached to the back surface of each device. A processing method,
A cutting groove forming step of forming a cutting groove having a depth obtained by subtracting a predetermined remaining thickness from the finished thickness of the device along the street from the surface side of the wafer;
A protective member attaching step for attaching a protective member to the surface of the wafer on which the cutting groove forming step has been performed;
A back surface grinding step of grinding the back surface of the wafer on which the protective member attaching step has been performed, and grinding to leave the predetermined remaining thickness to the bottom surface of the cutting groove;
The adhesive film is attached to the back surface of the wafer subjected to the back grinding process, and a dicing tape is attached to the adhesive film side, and the outer peripheral portion of the dicing tape is supported by an annular frame, and the protection is attached to the wafer surface. A wafer support step for peeling the member;
A laser processing step of irradiating a laser beam from the surface side of the wafer on which the wafer support step has been performed to the bottom of the cutting groove to break the remaining portion of the wafer having the predetermined remaining thickness and the adhesive film.
A method for processing a wafer.   The wafer processing method according to claim 1, wherein the thickness of the remaining portion is set to 5 to 10 μm from the bottom of the cutting groove.   The laser processing step irradiates the wafer and the adhesive film with a laser beam having a wavelength that absorbs the wafer and the adhesive film along the bottom of the cutting groove from the surface side of the substrate. The wafer processing method according to claim 1, wherein the wafer is formed.   The laser processing step irradiates a laser beam having a wavelength that is transparent to the wafer and the adhesive film with a focusing point positioned at the remaining portion of the wafer and an intermediate portion of the adhesive film, and irradiates the remaining portion of the wafer and the adhesive film. The wafer processing method according to claim 1, wherein the modified layer is formed.   5. The device separation step according to claim 1, further comprising a device separation step of expanding the dicing tape to which the wafer is adhered after performing the laser processing step to separate the wafer into individual devices along the street. The processing method of the wafer as described.

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