JP2012227368A - Adhesive tape, and method of processing wafer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an adhesive tape capable of reducing the occurrence of static electricity and a method of processing a wafer using the adhesive tape.SOLUTION: An adhesive tape supports a wafer having a surface where a plurality of devices are formed and partitioned by predetermined division lines, and comprises: a sheet substrate; an adhesive layer stacked on the surface of the sheet substrate; and an antistatic layer stacked on the rear face of the sheet substrate.

Description

  The present invention relates to an adhesive tape used when an external force is applied to a wafer, and a wafer processing method using the adhesive tape.

  A wafer such as a silicon wafer or a sapphire wafer formed on the surface by dividing a plurality of devices such as IC, LSI, LED, etc. by dividing lines is divided into individual devices by a processing apparatus, and the divided devices are mobile phones, Widely used in various electrical equipment such as personal computers.

  A dicing method using a cutting device called a dicer is widely used for dividing the wafer. In the dicing method, a wafer is cut by cutting a wafer into a wafer while rotating a cutting blade having a thickness of about 30 μm by solidifying abrasive grains such as diamond with a metal or a resin at a high speed of about 30000 rpm. Divide into

  On the other hand, in recent years, a laser processing groove is formed by irradiating a wafer with a pulsed laser beam having a wavelength that absorbs the wafer, and an external force is applied to the wafer by a braking device along the laser processing groove. A method of cleaving a wafer and dividing it into individual devices has been proposed (see, for example, Japanese Patent Laid-Open No. 10-305420).

  As another embodiment of a processing method using a laser beam, a condensing point of a laser beam having a wavelength transparent to the wafer (for example, 1064 nm) is positioned inside the wafer corresponding to the division line, and the laser beam Has been proposed in which an altered layer is formed inside the wafer by irradiating the wafer along the line to be divided, and then the wafer is cleaved by applying an external force to the wafer by a breaking device and divided into individual devices ( For example, see Japanese Patent No. 3408805).

  Formation of laser-processed grooves or deteriorated layers using a laser processing apparatus can increase the processing speed compared to a dicing method using a dicer, and it is relatively easy even for a wafer made of a material having high hardness such as sapphire or SiC. Can be processed.

  Further, since the processed groove or the deteriorated layer can be formed to have a narrow width of, for example, 10 μm or less, the amount of devices taken per wafer can be increased as compared with the case of processing by the dicing method.

  In the processing of a wafer by a laser processing apparatus, the wafer is attached to a dicing tape whose outer peripheral portion is attached to an annular frame, and the wafer is supported by the annular frame via the dicing tape. Then, the laser beam is irradiated in a state where the wafer is sucked and held via the dicing tape on the chuck table of the laser processing apparatus.

JP-A-10-305420 Japanese Patent No. 3408805

  However, when the wafer is cut using an expanding device (dividing device), the adhesive tape to which the wafer is attached is expanded in the radial direction and external force is applied to the wafer. Therefore, the expanding device is used when the adhesive tape is expanded. There is a problem that static electricity is generated in the adhesive tape due to the friction with the device, and the function of the device is destroyed, or the debris at the time of wafer cutting adheres to the device and the quality of the device is deteriorated.

  This invention is made | formed in view of such a point, The place made into the objective is providing the processing method of the wafer which uses the adhesive tape which can suppress generation | occurrence | production of static electricity, and this adhesive tape.

  According to the first aspect of the present invention, there is provided an adhesive tape for supporting a wafer formed on a surface by dividing a plurality of devices by a predetermined division line, and is laminated on the surface of the sheet-like substrate. There is provided an adhesive tape comprising: the adhesive layer formed, and an antistatic layer laminated on the back surface of the sheet-like substrate.

  According to the second aspect of the present invention, there is provided a wafer processing method in which a plurality of devices are partitioned by a predetermined division line and a wafer formed on the surface is divided into individual devices, and an annular shape having an opening for receiving the wafer. An integration step in which the wafer is accommodated in the opening of the frame, the adhesive tape according to claim 1 is attached to the wafer and the annular frame and integrated with the wafer unit, and the wafer is supported by the annular frame; After performing the split starting point forming step for forming the split starting point along the planned split line of the wafer before or after the integrating step, and after the integrating step and the split starting point forming step, via the adhesive tape A wafer dividing step of applying an external force to the wafer to divide the wafer into individual devices along the division line on which the starting point of the division is formed. The wafer processing method, characterized in that Bei the is provided.

  Since the antistatic layer is formed on the back surface of the sheet-like base material of the pressure-sensitive adhesive tape of the present invention, the wafer on which the separation starting point is formed is pasted on the pressure-sensitive adhesive tape along the planned dividing line. Even if the wafer is divided by expanding in the radial direction, the static electricity generated on the adhesive tape is suppressed and the device functions are destroyed, and the quality of the device deteriorates due to adhesion of the divided waste. To solve the problem.

It is a perspective view of a laser processing apparatus. It is a perspective view explaining an integration process. It is a block diagram of a laser beam irradiation unit. It is a perspective view which shows the division | segmentation starting point formation process which forms the laser processing groove | channel used as the starting point of a division | segmentation along the division | segmentation planned line of a wafer. It is a perspective view which shows the state which sprays the static eliminating agent on the back surface of an adhesive tape. It is a perspective view of an expanding device (dividing device). It is a longitudinal cross-sectional view which shows the division | segmentation process of a wafer.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 shows a schematic configuration diagram of a laser processing apparatus 2 suitable for carrying out the wafer processing method of the present invention. The laser processing apparatus 2 includes a first slide block 6 mounted on a stationary base 4 so as to be movable in the X-axis direction.

  The first slide block 6 is moved along the pair of guide rails 14 in the machining feed direction, that is, the X-axis direction, by the machining feed means 12 including the ball screw 8 and the pulse motor 10.

  A second slide block 16 is mounted on the first slide block 6 so as to be movable in the Y-axis direction. That is, the second slide block 16 is moved in the indexing direction, that is, the Y-axis direction along the pair of guide rails 24 by the indexing feeding means 22 constituted by the ball screw 18 and the pulse motor 20.

  A chuck table 28 is mounted on the second slide block 16 via a cylindrical support member 26, and the chuck table 28 can be moved in the X-axis direction and the Y-axis direction by the processing feed means 12 and the index feed means 22. . The chuck table 28 is provided with a clamp 30 for clamping the wafer sucked and held by the chuck table 28.

  A column 32 is erected on the stationary base 4, and a casing 35 for accommodating the laser beam irradiation unit 34 is attached to the column 32. As shown in FIG. 3, the laser beam irradiation unit 34 includes a laser oscillator 62 that oscillates a YAG laser or a YVO4 laser, a repetition frequency setting unit 64, a pulse width adjustment unit 66, and a power adjustment unit 68. .

  The pulse laser beam adjusted to a predetermined power by the power adjusting means 68 of the laser beam irradiation unit 34 is reflected by the mirror 70 of the condenser 36 attached to the tip of the casing 35 and further collected by the condenser objective lens 72. The wafer 11 is irradiated with light and applied to the chuck table 28.

  At the tip of the casing 35, an image pickup means 38 for detecting a processing region to be laser processed aligned with the condenser 36 in the X-axis direction is disposed. The image pickup means 38 includes an image pickup element such as a normal CCD that picks up an image of a processing region of a semiconductor wafer with visible light.

  The imaging unit 38 further includes an infrared irradiation unit that irradiates the semiconductor wafer with infrared rays, an optical system that captures the infrared rays irradiated by the infrared irradiation unit, and an infrared CCD that outputs an electrical signal corresponding to the infrared rays captured by the optical system. Infrared imaging means composed of an infrared imaging element such as the above is included, and the captured image signal is transmitted to a controller (control means) 40.

  The controller 40 includes a central processing unit (CPU) 42 that performs arithmetic processing according to a control program, a read-only memory (ROM) 44 that stores a control program, and a random read / write that stores arithmetic results. An access memory (RAM) 46, a counter 48, an input interface 50, and an output interface 52 are provided.

  Reference numeral 56 denotes a processing feed amount detection means comprising a linear scale 54 disposed along the guide rail 14 and a read head (not shown) disposed on the first slide block 6. Is input to the input interface 50 of the controller 40.

  Reference numeral 60 denotes index feed amount detection means comprising a linear scale 58 disposed along the guide rail 24 and a read head (not shown) disposed on the second slide block 16. The detection signal is input to the input interface 50 of the controller 40.

  An image signal picked up by the image pickup means 38 is also input to the input interface 50 of the controller 40. On the other hand, a control signal is output from the output interface 52 of the controller 40 to the pulse motor 10, the pulse motor 20, the laser beam irradiation unit 34, and the like.

  As shown in FIG. 2, on the surface 11 a of the wafer 11 to be processed by the laser processing apparatus 2, a plurality of streets (division planned lines) 13 are formed orthogonally and are partitioned by the orthogonal streets 13. A device 15 is formed in each region. The wafer 11 includes a device region 17 in which a large number of devices 15 are formed, and an outer peripheral surplus region 19 surrounding the device region 17 on the surface 11a.

  The back surface 11b of the wafer 11 is attached to a dicing tape T that is an adhesive tape, and the outer peripheral portion of the dicing tape T is attached to an annular frame F to form a wafer unit 21. The dicing tape T is configured by arranging an adhesive layer made of, for example, an acrylic resin on a sheet base material such as vinyl chloride.

  In the wafer unit 21, the wafer 11 is supported by the annular frame F via the dicing tape T. During laser processing, the wafer 11 is sucked and held by the chuck table 28 via the dicing tape T, and the annular frame is held by the clamp 30. F is clamped and fixed.

  Next, a wafer processing method according to an embodiment of the present invention will be described in detail with reference to FIGS. First, a pattern for imaging the processing region of the wafer 11 with the imaging unit 38 and aligning the condenser 36 of the laser beam irradiation unit 34 that irradiates the laser beam with the street 13 extending in the first direction. Image processing such as matching is executed to align the laser beam irradiation position. Next, the chuck table 28 is rotated by 90 degrees, and the alignment between the street 13 extending in the second direction and the condenser 28 is performed.

  When the alignment process described above is completed, in the first embodiment of the processing method of the present invention, a pulsed laser beam having a wavelength that is absorptive with respect to the wafer 11 is passed through a condenser 36 as shown in FIG. Irradiation is started from one end of the street 13 to be processed of the wafer 11, the chuck table 28 is moved at a predetermined processing feed speed in the direction indicated by the arrow X 1, and a laser processing groove 74 that becomes a starting point of division along the street 13. Form.

  If the laser processing groove 74 as the starting point of the division is formed along all the streets 13 extending in the first direction, the chuck table 28 is rotated 90 degrees and then all the streets extending in the second direction. A similar laser processing groove 74 is formed along 13.

  Examples of laser processing conditions in the first embodiment are as follows, for example.

Light source: YAG pulse laser Wavelength: 355 nm (third harmonic of YAG laser)
Average output: 3.5W
Condensing spot diameter: 10 μm
Repetition frequency: 100 kHz
Processing feed rate: 100 mm / s

  The division starting point forming step, which is the starting point of the division along the planned division line 13 of the wafer, can also be carried out using a laser beam having a wavelength that is transmissive to the wafer 11. In the second embodiment, the condensing point of the pulse laser beam having transparency to the wafer 11 from the condenser 36 is aligned with the inside of the wafer 11, and the pulse laser beam is irradiated along the street 13 while chucking. The table 28 is moved at a predetermined feed speed in the direction indicated by the arrow X1 in FIG. 4 to form a deteriorated layer inside the wafer 11.

  An altered layer is formed inside the wafer 11 along all the streets 13 extending in the first direction, and then the chuck table 28 is rotated 90 degrees to extend in a second direction orthogonal to the first direction. A similar altered layer is formed inside the wafer along all the streets 13. This altered layer is formed as a melt rehardened layer.

  The laser processing conditions in the second embodiment are as follows, for example.

Light source: YAG pulse laser Wavelength: 1064 nm
Average output: 1.0W
Condensing spot diameter: 1 μm
Repetition frequency: 100 kHz
Processing feed rate: 50 mm / s

  After performing the division starting point forming step of the first embodiment or the second embodiment, as shown in FIG. 5, the back surface of the dicing tape T is charged by spraying the static electricity removing agent 78 from the back surface side of the dicing tape T by the spray nozzle 76. A prevention layer is formed.

  As the static eliminating agent 78, “Static eliminating spray SB-8” provided by Showa Grove Co., Ltd. can be used. In addition, you may make it spray this electrostatic removal agent 78 to the back surface side of the dicing tape T before implementing a division | segmentation starting point formation process.

  A wafer that divides the wafer 11 into individual chips along a laser processing groove 74 that serves as a division starting point using an expanding apparatus (dividing apparatus) 80 shown in FIG. A division process is performed.

  The expanding apparatus 80 shown in FIG. 6 includes a frame holding unit 82 that holds the annular frame F, and a tape expansion unit 84 that extends the dicing tape T attached to the annular frame F held by the frame holding unit 82. Yes.

  The frame holding means 82 includes an annular frame holding member 86 and a plurality of clamps 88 as fixing means arranged on the outer periphery of the frame holding member 86. An upper surface of the frame holding member 86 forms a mounting surface 86a on which the annular frame F is mounted, and the annular frame F is mounted on the mounting surface 86a.

  The annular frame F placed on the placement surface 86 a is fixed to the frame holding means 86 by a clamp 88. The frame holding means 82 configured as described above is supported by the tape extending means 84 so as to be movable in the vertical direction.

  The tape expansion means 84 includes an expansion drum 90 disposed inside the annular frame holding member 86. The upper end of the expansion drum 90 is closed with a lid 92. The expansion drum 90 has an inner diameter that is smaller than the inner diameter of the annular frame F and larger than the outer diameter of the wafer 11 attached to the dicing tape T attached to the annular frame F.

  The expansion drum 90 has a support flange 94 integrally formed at the lower end thereof. The tape expanding means 84 further includes driving means 96 for moving the annular frame holding member 86 in the vertical direction. The driving means 96 is composed of a plurality of air cylinders 98 disposed on a support flange 94, and the piston rod 100 is connected to the lower surface of the frame holding member 86.

  The driving means 96 composed of a plurality of air cylinders 98 includes an annular frame holding member 86, a reference position where the mounting surface 86a is substantially the same height as the surface of the lid 92 which is the upper end of the expansion drum 90, and an expansion. It moves up and down between the extended position below the upper end of the drum 90 by a predetermined amount.

  The dividing process of the wafer 11 performed using the expanding apparatus 80 configured as described above will be described with reference to FIG. As shown in FIG. 7A, the annular frame F that supports the wafer 11 via the dicing tape T is placed on the placement surface 86 a of the frame holding member 86 and fixed to the frame holding member 86 by the clamp 88. To do. At this time, the frame holding member 86 is positioned at a reference position where the mounting surface 86 a is substantially flush with the upper end of the expansion drum 90.

  Next, the air cylinder 98 is driven to lower the frame holding member 86 to the extended position shown in FIG. Accordingly, the annular frame F fixed on the mounting surface 86a of the frame holding member 86 is lowered, so that the dicing tape T mounted on the annular frame F abuts on the upper edge of the expansion drum 90 and mainly has a radius. Expanded in the direction.

  As a result, radial tensile forces act on the wafer 11 adhered to the dicing tape T. When a tensile force is applied to the wafer 11 in a radial manner in this way, the laser processing groove 74 formed along the street 13 serves as a division starting point, and the wafer 11 is cleaved along the laser processing groove 74, and individual semiconductor chips ( Device) 15.

  In the case of the second embodiment in which an altered layer serving as a starting point for division is formed inside the wafer 11, if a tensile force acts radially on the wafer 11, the strength of the altered layer formed along the street 13 is reduced. Therefore, the deteriorated layer serves as a division starting point, and the wafer 11 is cut along the deteriorated layer and divided into individual semiconductor chips (devices) 15.

  As shown in FIG. 2, the silicon wafer 11 is supported by an annular frame F via a dicing tape T, irradiated with a laser beam at an interval of 1.0 mm to form a deteriorated layer inside the planned division line, and a 1.0 mm × Dividing into a plurality of 1.0 mm squares, the dicing tape T was expanded. When the back surface of the dicing tape T was rubbed, the charge amount of the wafer 11 was compared with the number of debris having a size of 5 μm or more adhering to the periphery, and the results shown in Table 1 were obtained.

  As is apparent from Table 1, in the pressure-sensitive adhesive tape of the present invention having the antistatic layer on the back surface of the dicing tape T, the charge amount of the wafer is remarkably reduced as compared with the conventional pressure-sensitive adhesive tape having no antistatic layer. . Furthermore, the number of chips on the chip surface and the number of chips on the tape surface are significantly reduced as compared with the conventional adhesive tape.

  The dicing tape (adhesive tape) T of the present embodiment is formed from a sheet-like substrate, an adhesive layer disposed on the surface of the sheet-like substrate, and an antistatic layer coated on the back surface of the sheet-like substrate. Therefore, even when the antistatic layer formed on the back surface of the dicing tape T is in sliding contact with the lid 92 of the expansion drum 90 during tape expansion shown in FIG. Thus, it is possible to solve the problem that the function of the device 15 is destroyed when the dividing step is performed, and the quality of the device 15 is deteriorated due to the attachment of scraps when the wafer 11 is cut.

T Dicing tape (adhesive tape)
F Annular frame 2 Laser processing equipment 11 Wafer 13 Scheduled division line (street)
15 Device 28 Chuck table 34 Laser beam irradiation unit 36 Condenser 74 Laser processing groove 80 Expanding device (dividing device)
82 Frame holding means 84 Tape expansion means 90 Expansion drum 98 Air cylinder

Claims (2)

A plurality of devices are pressure-sensitive adhesive tapes that support a wafer that is partitioned by lines to be divided and formed on the surface,
A sheet-like substrate;
An adhesive layer laminated on the surface of the sheet-like substrate;
An antistatic layer laminated on the back surface of the sheet-like substrate;
A pressure-sensitive adhesive tape comprising: A wafer processing method in which a plurality of devices are partitioned by lines to be divided and a wafer formed on the surface is divided into individual devices,
A wafer is accommodated in the opening of an annular frame having an opening for accommodating a wafer, and the adhesive tape according to claim 1 is bonded to the wafer and the annular frame to be integrated with the wafer unit, and the wafer is integrated into the annular frame. The integration process supported by
Before or after the integration step, a split start point forming step for forming a split start point along the planned split line of the wafer;
After performing the integration step and the division starting point forming step, an external force is applied to the wafer through the adhesive tape, and the wafer is separated into individual devices along the planned division line where the division starting point is formed. A wafer splitting process,
A wafer processing method characterized by comprising:

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