JP5943727B2 - Breaking method of adhesive film - Google Patents

Description

  The present invention relates to a method for breaking an adhesive film for die bonding.

  For example, in the semiconductor device manufacturing process, devices such as IC and LSI are formed in each region partitioned by planned dividing lines (streets) formed in a lattice pattern on the surface of a semiconductor wafer having a substantially disk shape. Individual devices are manufactured by dividing a wafer along a predetermined line.

  As a dividing device that divides a semiconductor wafer into individual devices, a cutting device generally called a dicing device is used. This cutting device uses a cutting blade having a very thin cutting edge to cut a semiconductor wafer along a planned dividing line. Cutting and dividing into individual semiconductor devices.

  The divided semiconductor devices are die-bonded (adhered) to a metal substrate (lead frame), a tape substrate or the like, and individual semiconductor chips are manufactured by dividing the metal substrate or the tape substrate. The semiconductor chip thus manufactured is widely used in various electric devices such as mobile phones and personal computers.

  In order to die-bond a semiconductor device on a substrate, there is a method in which an adhesive such as solder, AU-Si, or resin paste is supplied to the mounting position of the semiconductor device on the substrate, and the semiconductor device is mounted and bonded thereon. It is used.

  In recent years, as disclosed in, for example, Japanese Patent Application Laid-Open No. 11-219962, a method in which a DAF (die attach film), which is an adhesive film for die bonding, is bonded in advance to the back surface of a semiconductor wafer has been widely adopted. Yes.

  That is, by dividing the semiconductor wafer to which DAF is bonded into individual devices, a semiconductor device having DAF bonded to the back surface is formed. Thereafter, die bonding of the back surface of the semiconductor device to the substrate via the DAF is advantageous in that the adhesive used is minimized and the mounting area of the semiconductor device can be minimized.

  Japanese Patent Application Laid-Open No. 2006-49591 discloses an adhesive film breaking method and breaking device that can efficiently and reliably break DAF while cooling.

Japanese Patent Laid-Open No. 11-219962 JP 2006-49591 A

  In the method for breaking the adhesive film as disclosed in Patent Document 2, the expanded sheet between the outer periphery of the wafer and the inner periphery of the annular frame is pressed and expanded in a state where the annular frame is fixed, and is attached to the expanded sheet. The attached adhesive film is broken.

  Therefore, since the external force applied to the adhesive film is not uniform within the surface of the adhesive film, for example, when the chip size is 1 mm square or less and the adhesive film is cooled, there is a problem that a region that is not broken even occurs. There is.

  This invention is made | formed in view of such a point, The place made into the objective is providing the fracture | rupture method of the adhesive film which can reduce that the area | region which is not fractured | rupture generate | occur | produces.

  According to the first aspect of the present invention, there is provided a method for breaking an adhesive film, wherein the adhesive film is attached to the back surface of the wafer divided into individual chips, and the wafer is attached to the expanded sheet via the adhesive film. A wafer unit forming step for forming a wafer unit supported by an annular frame, and after performing the wafer unit forming step, the wafer unit has a diameter equal to or larger than the wafer of the wafer unit, and the wafer is interposed through the expanded sheet. A flexible member that can extend and contract, a sealed space formed immediately below the flexible member, a cooling gas inflow passage connected to a cooling gas source that supplies cooling gas to the sealed space, and a gas in the sealed space The wafer unit is placed on a support table having a gas discharge path for discharging the support table, and the support table A wafer unit fixing step for fixing the frame with a frame fixing means disposed on the outer periphery of the wafer, and after performing the wafer unit fixing step, a cooling gas is introduced into the sealed space and the expanded sheet is attached together with the flexible member. And a breaking step of breaking along the chip while cooling the adhesive film by discharging a cooling gas from the gas discharge passage while expanding.

  According to the second aspect of the present invention, there is provided a method for breaking an adhesive film, wherein the adhesive film is attached to the back surface of the wafer on which the division starting points are formed, and the wafer is attached to the expanded sheet through the adhesive film. A wafer unit forming step for forming a wafer unit supported by an annular frame, and after performing the wafer unit forming step, a wafer having a diameter equal to or larger than that of the wafer of the wafer unit is passed through the expanded sheet. A flexible member that can be stretched and supported, a sealed space formed below the flexible member, a cooling gas inflow passage connected to a cooling gas source that supplies cooling gas to the sealed space, and a gas in the sealed space The wafer unit is placed on a support table having a gas discharge path for discharging, and the support table A wafer unit fixing step for fixing the frame with a frame fixing means disposed around the periphery, and after performing the wafer unit fixing step, a cooling gas flows into the sealed space to expand the expand sheet together with the flexible member. A break step of cooling the adhesive film by discharging the cooling gas from the gas discharge passage and breaking the adhesive film together with the wafer along the dividing starting point. A method is provided.

  In the method for breaking an adhesive film of the present invention, a flexible member having a diameter equal to or greater than that of a wafer and supporting the wafer via an expanded sheet, a sealed space formed immediately below the flexible member, and the sealed The wafer is supported by a support table having a cooling gas inflow path connected to a cooling gas source for supplying cooling gas to the space and a gas exhaust path for discharging the gas in the sealed space, and is arranged on the outer periphery of the support table. The frame is fixed by the frame fixing means provided.

  Thereafter, the flexible member is expanded by allowing the cooling gas to flow into the sealed space, and the expanded sheet is expanded. When the expanded sheet is expanded, an external force is uniformly applied to the entire adhesive film, so that it is possible to reduce a possibility that a region that is not broken is generated in the adhesive film. In addition, since the cooling fluid flows in and is discharged into the sealed space, the adhesive film can always be cooled, and the adhesive film can be efficiently broken.

It is a perspective view which shows a cutting step. It is a perspective view which shows a back surface grinding step. It is a perspective view of the wafer unit of a 1st embodiment. It is a longitudinal cross-sectional view of the dividing device which shows a wafer unit fixing step. It is a longitudinal cross-sectional view of the dividing device which shows a fracture | rupture step. It is a perspective view which shows a modified layer formation step. It is a block diagram of a laser beam generation unit. It is a perspective view of the wafer unit of a 2nd embodiment. It is a longitudinal cross-sectional view of the dividing device which shows a wafer unit fixing step. It is a longitudinal cross-sectional view of the dividing device which shows a fracture | rupture step.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Referring to FIG. 1, a perspective view of a cutting groove forming step performed using the cutting device 10 is shown. The cutting device 10 includes a suction holding portion, a chuck table 8 that can rotate and move in the X-axis direction, a cutting unit 12, and an alignment unit that can move integrally with the cutting unit 12 in the Y-axis direction and the Z-axis direction. 14 is included.

  The cutting unit 12 includes a spindle 16 that is rotationally driven by a motor (not shown), and a cutting blade 18 that is attached to the tip of the spindle 16. The alignment unit 14 includes an imaging unit 20 having a CCD camera and a microscope.

  In order to perform the cutting groove forming step, the semiconductor wafer 11 is placed on the chuck table 8 with its surface 11a facing up. The wafer 11 is sucked and held on the chuck table 8 by operating a suction means (not shown).

  On the surface 11 a of the semiconductor wafer 11, devices 15 such as ICs and LSIs are formed in each area partitioned by division lines (streets) 13 formed in a lattice shape.

  The chuck table 8 that sucks and holds the wafer 11 is positioned directly below the imaging unit 20 by a processing feed mechanism (not shown). When the chuck table 8 is positioned immediately below the imaging unit 20, an alignment operation for detecting a cutting region in which a cutting groove is to be formed in the wafer 11 is performed by the imaging unit 20 and a control unit (not shown).

  In other words, the imaging unit 20 and a control unit (not shown) execute image processing such as pattern matching for aligning the division line 13 extending in the first direction of the wafer 11 with the cutting blade 18 to perform cutting. Perform region alignment. Next, after the chuck table 8 is rotated by 90 degrees, the same alignment is performed on the planned dividing line 13 extending in the second direction orthogonal to the first direction.

  After the alignment, the chuck table 8 holding the wafer 11 is moved to the cutting start position in the cutting area. Then, the cutting blade 18 is moved downward in the direction indicated by the arrow A at a high speed (for example, 30000 rpm) to perform a predetermined amount of cutting feed. This cutting feed amount is set such that the outer peripheral edge of the cutting blade 18 is a depth position (for example, 100 μm) corresponding to the finished thickness of the device from the surface 11 a of the wafer 11.

  If the cutting blade 18 is cut and fed, the chuck table 8 is processed and fed in the X-axis direction, that is, the direction indicated by the arrow X1 while the cutting blade 18 is rotated. A cutting groove 17 having a depth (for example, 100 μm) corresponding to the thickness is formed. This cutting groove forming step is performed along all the division lines 13 formed on the wafer 11.

  Next, a surface protection tape 21 for grinding is attached to the surface 11 a of the wafer 11. For example, a polyolefin tape having a thickness of about 150 μm is used as the surface protection tape 21.

  Next, the rear surface 11b of the wafer 11 with the protective tape 21 attached to the front surface is ground, and the cutting groove exposing step is performed to divide the wafer 11 into individual devices 15 by exposing the cutting grooves 17 to the rear surface 11b. . This cutting groove exposing step is performed by a grinding device 22 having a chuck table 24 and a grinding unit 26 as shown in FIG.

  The grinding unit 26 includes a spindle 28 that is rotationally driven by a motor, a wheel mount 30 that is fixed to the tip of the spindle 28, and a grinding wheel 32 that is detachably attached to the wheel mount 30 by a plurality of screws 34. Yes. The grinding wheel 32 includes an annular base 36 and a plurality of grinding wheels 38 fixed to the outer periphery of the lower end of the annular base 36.

  In the cutting groove exposing step, the surface protection tape 21 attached to the front surface 11 a of the wafer 11 is sucked and held on the chuck table 24 to expose the back surface 11 b of the wafer 11. The chuck table 24 is rotated in the direction indicated by the arrow a at, for example, 300 rpm. The grinding wheel 32 is rotated in the direction indicated by the arrow b at, for example, 6000 rpm, and the grinding wheel 38 is brought into contact with the back surface 11b of the wafer 11, whereby the back surface 11b of the wafer 11 is ground. This grinding is performed until the cutting groove 17 is exposed on the back surface 11 b of the wafer 11.

  When grinding is performed until the cutting groove 17 is exposed on the back surface 11 b, the wafer 11 is divided into individual chips 15 </ b> A having devices 15. In addition, since the surface protection tape 21 is stuck on the surface 11a of the divided chips 15A, the shape of the wafer 11 is maintained without being separated.

  Next, as shown in FIG. 3, the back surface 11 b of the wafer 11 is attached to a DAF (die attach film) 23 that is an adhesive film for die bonding attached to the expanded sheet T, and the outer peripheral edge of the expanded sheet T is attached. The wafer unit 25 is formed by being attached to the annular frame F. Then, the surface protection tape 21 is peeled from the surface 11 a of the wafer 11.

  Next, using a dividing device (expanding device) 40 as shown in FIG. 4, a breaking step for breaking the DAF 23 along the chip 15A is performed. The dividing device 40 includes a frame holding unit 42 that holds the annular frame F.

  The frame holding unit 42 includes an annular frame holding member 44 and a plurality of clamps 46 as fixing means disposed on the outer periphery of the frame holding member 44. An upper surface of the frame holding member 44 forms a mounting surface 44a on which the annular frame F is mounted, and the annular frame F of the wafer unit 25 is mounted on the mounting surface 44a.

  The annular frame holding member 44 is moved in the vertical direction by the moving unit 48. The moving unit 48 has a plurality of air cylinders 50, and the piston rod 52 of the air cylinder 50 supports the annular frame holding member 44.

  A support table 54 is disposed inside the annular frame holding member 44. The support table 54 has a circular recess 56 at its upper end, and the circular recess 56 is closed by a flexible member 58 that can be expanded and contracted, and a sealed space 60 is defined immediately below the flexible member 58.

  The support table 54 is formed with a cooling gas inflow passage 62 for supplying cooling gas into the sealed space 60 and a gas discharge passage 68 for discharging the gas in the sealed space 60. The cooling gas inflow passage 62 is connected to a cooling air source 66 through an electromagnetic switching valve 64. The gas discharge path 68 is connected to the atmosphere via the flow rate adjusting means 70.

  Reference numeral 72 denotes an air cylinder, and a piston rod 74 of the air cylinder 72 supports the support table 54. Therefore, by driving the air cylinder 72, the support table 54 is moved up and down.

  Hereinafter, the operation of the dividing apparatus 40 configured as described above will be described. First, as shown in FIG. 4, the DAF 23 of the wafer unit 25 is placed on a stretchable flexible member 58 disposed on the upper portion of the support table 54, and the annular frame F is placed on the placement surface 44 a of the frame holding member 44. A wafer unit fixing step is performed in which the annular frame F is clamped by the clamp 46 and fixed.

  After performing the wafer unit fixing step, as shown in FIG. 5, the electromagnetic switching valve 64 is switched to the communication position, the cooling gas inflow passage 62 is connected to the pressurized cooling air source 66, and the sealed space 60 is pressurized. Introduced cooling gas. And the flow volume adjustment means 70 is adjusted appropriately and the gas in the sealed space 60 is discharged from the gas discharge path 68 at a predetermined ratio.

  By setting the inflow amount of the pressurized cooling gas flowing in through the cooling gas inflow passage 62 to be larger than the exhaust gas amount, the flexible member 58 that can expand and contract is introduced into the sealed space 60 under the pressurized cooling state. As shown in FIG. 5, the expanded sheet T is expanded into a hemispherical shape by the gas. As a result, since an external force is uniformly applied to the entire DAF 23, the DAF 23 is broken along the chip 10A while being cooled.

  Thus, in the adhesive film breaking step using the dividing device 40 of the present embodiment, the pressurized cooling gas flows into the sealed space 60 and is discharged at a predetermined rate. The flexible member 58 is expanded into a hemispherical shape by the introduced pressurized gas, and the expanded sheet T is expanded into a hemispherical shape.

  As a result, since an external force is uniformly applied to the entire DAF 23, the DAF 23 can be reliably broken along the chip 15A. Also, since fresh pressurized cooling gas is always introduced into the sealed space 60, the DAF 23 can be continuously cooled, and the DAF 23 can be efficiently broken.

  If the air cylinder 70 is operated to push up the support table 54 or the air cylinder 50 is operated to lower the frame holding member 44 in addition to the introduction of the pressurized cooling gas into the sealed space 60, the expanded The sheet T can be further expanded, and the DAF 23 can be more reliably broken.

  Next, with reference to FIG. 6 thru | or FIG. 10, the fracture | rupture method of the adhesive film of 2nd Embodiment of this invention is demonstrated. In the method for breaking the adhesive film of the present embodiment, a split starting point forming step for forming a split starting point on the wafer 11 is performed. This division starting point forming step is performed by a modified layer forming step of forming a modified layer inside the wafer 11 using, for example, a laser processing device 76 as shown in FIG.

  The laser processing apparatus 76 includes a laser beam irradiation unit 80. The laser beam irradiation unit 80 includes a laser beam generation unit 84 (see FIG. 7) housed in a casing 82, and a collector attached to the tip of the casing 82. An optical device (laser processing head) 86 is included.

  As shown in FIG. 7, the laser beam generation unit 84 includes a laser oscillator 88 that oscillates a YAG laser or a YVO4 laser, a repetition frequency setting means 90, a pulse width adjustment means 92, and a power adjustment means 94. .

  In this modified layer forming step, the wafer 11 is imaged by the imaging unit 96, and alignment is performed so that the region corresponding to the planned division line 13 is aligned with the condenser 86 in the X-axis direction. For this alignment, well-known image processing such as pattern matching is used.

  After the alignment of the division line 13 extending in the first direction is performed, the alignment of the division line 13 extending in the second direction orthogonal to the first direction after rotating the chuck table 78 by 90 degrees is similarly performed. carry out.

  After the alignment, the laser beam condensing point is positioned inside the wafer 11, and the laser beam is irradiated from the surface 11 a side of the wafer 11 along the planned division line 13, so that the modification that becomes the division starting point inside the wafer 11 is performed. A modified layer forming step for forming the quality layer 27 is performed.

  The modified layer 27 is formed inside the wafer 11 corresponding to all the division lines 13 that extend in the first direction while indexing and feeding the chuck table 78 in the Y-axis direction. Next, after the chuck table 78 is rotated by 90 degrees, a similar modified layer 27 is formed inside the wafer 11 corresponding to the division line 17 extending in the second direction orthogonal to the first direction.

  The modified layer 27 refers to a region where the density, refractive index, mechanical strength, and other physical characteristics are different from the surroundings. For example, it includes a melt rehardening region, a crack region, a dielectric breakdown region, a refractive index change region, and the like, and also includes a region in which these regions are mixed.

  The processing conditions in this modified layer forming step are set as follows, for example.

Light source: LD excitation Q switch Nd: YVO 4 pulse laser Wavelength: 1064 nm
Repetition frequency: 100 kHz
Pulse output: 10μJ
Condensing spot diameter: φ1μm
Processing feed rate: 100 mm / sec

  The division starting point is not limited to the modified layer 27 formed inside the wafer 11 described above, and the wafer is irradiated with a laser beam having a wavelength that is absorptive to the wafer, and the division starting point is obtained by ablation processing. A laser processing groove to be formed may be formed on the wafer. Alternatively, the wafer 11 may be cut incompletely with a cutting blade of a cutting device to form a cutting groove, and this cutting groove may be used as a division starting point.

  After performing the modified layer forming step, the back surface 11b of the wafer 11 is attached to the DAF 23 attached to the expanded sheet T, and the outer peripheral edge of the expanded sheet T is attached to the annular frame F as shown in FIG. A wafer unit 25A is formed.

  After performing the wafer unit forming step, a breaking step for breaking the adhesive film 23 together with the wafer 11 along the dividing starting point (modified layer) is performed using the dividing device (expanding device) 40.

  In this breaking step, as shown in FIG. 9, the DAF 23 of the wafer unit 25 </ b> A is placed on the stretchable flexible member 58 disposed on the support table 54, and the annular frame F is placed on the frame holding member 44. A wafer unit fixing step of mounting on the mounting surface 44 a and clamping the annular frame F with the clamp 46 is performed.

  Next, similarly to the first embodiment described with reference to FIG. 5, as shown in FIG. 10, the electromagnetic switching valve 64 is switched to the communication position, and the cooling gas inflow passage 62 is connected to the pressurized cooling air source 66. Then, the pressurized cooling gas is introduced into the sealed space 60. And the flow volume adjustment means 70 is adjusted appropriately and the gas in the sealed space 60 is discharged from the gas discharge path 68 at a predetermined ratio.

  By setting the inflow amount of the pressurized cooling gas flowing in through the cooling gas inflow passage 62 to be larger than the exhaust gas amount, the flexible member 58 that can expand and contract is introduced into the sealed space 60 under the pressurized cooling state. As shown in FIG. 10, the expanded sheet T is expanded into a hemispherical shape by the gas.

  As a result, the external force is uniformly applied to the entire DAF 23 together with the wafer 11, so that the wafer 11 and the DAF 23 are broken along the modified layer 27 that is the division starting point while being cooled.

  Also in this embodiment, in addition to the introduction of the pressurized cooling gas into the sealed space 60, the air cylinder 70 is operated to push up the support table 54, or the air cylinder 50 is operated to move the frame holding member 44. If pulled down, the expanded sheet T can be further expanded, and the wafer 11 and the DAF 23 can be more reliably broken.

11 Semiconductor wafer 13 Scheduled division line 15 Device 17 Cutting groove 18 Cutting blade 23 Adhesive tape (DAF)
25,25A Wafer unit 40 Dividing device (expanding device)
58 Stretchable flexible member 60 Sealed space 62 Cooling gas inflow path 68 Gas exhaust path 70 Flow rate adjusting means 80 Laser beam irradiation unit 84 Laser beam generation unit 86 Concentrator

Claims (2)

A method for breaking an adhesive film,
A wafer unit forming step for forming a wafer unit in a form in which an adhesive film is attached to the back surface of a wafer divided into individual chips and the wafer is attached to an expanded sheet via the adhesive film and supported by an annular frame. When,
After carrying out the wafer unit forming step, a stretchable flexible member having a diameter equal to or larger than that of the wafer of the wafer unit and supporting the wafer via the expanded sheet, and a seal formed immediately below the flexible member The wafer unit is mounted on a support table including a space, a cooling gas inflow passage connected to a cooling gas source for supplying a cooling gas to the sealed space, and a gas discharge passage for discharging the gas in the sealed space. And a wafer unit fixing step for fixing the frame by frame fixing means disposed on the outer periphery of the support table;
After performing the wafer unit fixing step, the cooling gas is allowed to flow into the sealed space to expand the expanded sheet together with the flexible member, and the cooling gas is discharged from the gas discharge path to cool the adhesive film. A breaking step to break along the tip;
A method for breaking an adhesive film, comprising: A method for breaking an adhesive film,
A wafer unit forming step for forming a wafer unit in a form in which an adhesive film is attached to the back surface of the wafer on which the division starting point is formed and the wafer is attached to the expanded sheet via the adhesive film and supported by an annular frame ,
After carrying out the wafer unit forming step, a stretchable flexible member having a diameter equal to or larger than that of the wafer of the wafer unit and supporting the wafer via the expanded sheet, and a seal formed below the flexible member The wafer unit is mounted on a support table including a space, a cooling gas inflow passage connected to a cooling gas source for supplying a cooling gas to the sealed space, and a gas discharge passage for discharging the gas in the sealed space. And a wafer unit fixing step for fixing the frame by frame fixing means disposed on the outer periphery of the support table;
After performing the wafer unit fixing step, the adhesive film is cooled by allowing cooling gas to flow into the sealed space and discharging the cooling gas from the gas discharge passage while expanding the expanded sheet together with the flexible member. A breaking step for breaking the adhesive film together with the wafer along the dividing starting point;
A method for breaking an adhesive film, comprising:

Images