JP2011204850A - Method of manufacturing semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of manufacturing a semiconductor device, such that a pressure-sensitive adhesive film for die bonding is easily arranged on a reverse surface of the semiconductor, without making the semiconductor device have a defect nor burring the pressure-sensitive adhesive film for die bonding and further, even if the semiconductor device is divided in a pre-dicing method.SOLUTION: The method of manufacturing the semiconductor device includes inserting a heating wire heated at predetermined temperature into a groove of a wafer held with a dicing tape, bringing the heating wire into contact with the pressure sensitive adhesive film for die bonding exposed on a bottom of the groove to fuse the film, and thus forming a fracture starting point on the pressure sensitive adhesive film for die bonding. Then the dicing tape mounted on an annular frame is expanded, to break the pressure sensitive adhesive film for die bonding from the fracture starting point along a predetermined division line.

Description

  The present invention relates to a method for manufacturing a semiconductor device in which a pressure-sensitive adhesive film for die bonding is disposed on the back surface.

  In recent semiconductor device technology, a stacked package in which a plurality of semiconductor devices such as MCP (Multi Chip Package) and SiP (System in Package) are stacked in order to achieve high density and miniaturization of devices. Is being used effectively.

  A semiconductor device constituting such a stacked package has a die bonding adhesive film called DAF (Die Attach Film) attached to the back surface, and the die bonding adhesive film maintains the stacked state of the semiconductor devices. Yes.

  This pressure-sensitive adhesive film for die bonding is widely used as a substitute for an adhesive such as a silver paste resin conventionally used when mounting a semiconductor device (semiconductor chip) on a lead frame.

  A semiconductor device having a die bonding adhesive film attached to the back surface is generally manufactured by the following method. First, the back surface of a semiconductor wafer in which a semiconductor device is formed in each region partitioned by a plurality of division lines provided in a lattice shape on the front surface is ground and thinned.

  Then, after sticking the die bonding adhesive film to the backside of the thinned semiconductor wafer, cut the semiconductor wafer along the planned dividing line with the cutting blade of the cutting device and cut the die bonding adhesive film. By dividing, a semiconductor device having a die-bonding adhesive film disposed on the back surface is manufactured (see, for example, JP-A-8-239636).

  On the other hand, it is desired that the thickness of a semiconductor device be reduced to several tens of μm or less with the recent reduction in size and thickness of electronic devices. As a method for forming such a thin semiconductor device, a cutting groove corresponding to the finished thickness of the device is formed on the front surface side of the wafer, and then the back surface of the wafer is ground to expose the cutting groove from the back surface side. A so-called dicing before grinding method in which a semiconductor wafer is divided into individual semiconductor devices is proposed in Japanese Patent Application Laid-Open No. 11-40520 and is being widely adopted.

  In the first dicing method, the back surface of the semiconductor wafer is ground and divided into individual semiconductor devices. Therefore, the die bonding pressure-sensitive adhesive film cannot be attached to the back surface before dividing into semiconductor devices.

  Therefore, after disposing a die bonding adhesive film such as DAF on the back side of the semiconductor wafer in a state where each divided device is integrally supported by the protective tape, the protective tape is removed to remove the die bonding adhesive film. By cutting, a semiconductor device having a die bonding adhesive film disposed on the back surface is formed. For cutting the die-bonding adhesive film, for example, a method of fusing the die-bonding adhesive film by irradiating a laser beam as disclosed in JP-A-2002-118081 has been proposed.

JP-A-8-239636 JP 11-40520 A JP 2002-118081 A

  However, when the semiconductor wafer and the die bonding adhesive film are simultaneously cut with the cutting blade as in the general method described above, the die bonding adhesive film is entangled with the cutting blade, causing problems such as clogging of the cutting blade. Thus, a semiconductor device formed by cutting from a semiconductor wafer has defects such as chips and cracks. In addition, whisker-like burrs are generated in the die-bonding adhesive film, and the burrs cause disconnection during wire bonding.

  In addition, when the above-described dicing method is adopted, if handling such as transportation is performed with each device supported by the protective tape, the protective tape is bent and the intervals between the devices may vary, or the cutting groove Bends. Thereafter, after a die bonding adhesive film such as DAF is disposed on the back surface side, the die bonding adhesive film is blown by irradiating a laser beam through the cutting groove.

  However, since the cutting groove is bent, it is difficult to irradiate a laser beam through the cutting groove, and a semiconductor device having a die bonding adhesive film on the back surface is manufactured by the first dicing method. There is a problem that is difficult.

  The present invention has been made in view of the above points, and the object of the present invention is to prevent the occurrence of defects in the semiconductor device, the generation of burrs in the adhesive film for die bonding, and the further dicing. It is an object of the present invention to provide a method for manufacturing a semiconductor device in which a die bonding adhesive film can be easily disposed on the back surface of a semiconductor device divided by the method.

  According to the present invention, there is provided a method for manufacturing a semiconductor device in which a die-bonding adhesive film is disposed on the back surface, and each device is formed in each region defined by division lines provided in a lattice shape on the surface. A groove having a depth corresponding to the finished thickness of the device is formed from the surface side of the wafer along the planned dividing line, and a protective tape is attached to the surface of the wafer on which the groove is formed. The back surface of the wafer divided into individual devices is divided by dividing the wafer into individual devices by grinding the back surface of the wafer to which the tape is attached to the finished thickness of the device, exposing the grooves from the back surface. The die bonding adhesive film is disposed on the outer periphery, and the die bonding adhesive film is attached to a ductile dicing tape whose outer peripheral portion is attached to the annular frame. The protective tape attached to the surface of the wafer is peeled off, and a heating wire having a thickness that can be inserted into the groove heated to a predetermined temperature is inserted into the groove of the wafer supported by the dicing tape, The heating wire is brought into contact with the die bonding pressure-sensitive adhesive film exposed at the bottom of the groove to melt the vicinity of the surface of the die bonding pressure-sensitive adhesive film to form a breakage starting point in the die bonding pressure-sensitive adhesive film. There is provided a method for manufacturing a semiconductor device, comprising the steps of extending the dicing tape mounted on the die and breaking the die-bonding adhesive film from the break starting point along the division line. The

  Preferably, in the semiconductor device manufacturing method, prior to performing the step of forming the fracture starting point, the dicing tape on which the wafer is mounted is expanded until the width of the groove becomes wider than the diameter of the heating wire. An expansion process is further provided.

  Preferably, the step of breaking the die bonding adhesive film from the break starting point is performed while cooling the dicing tape on which the wafer is mounted. Preferably, the heating temperature of the heating wire is in the range of 80 ° C to 300 ° C.

  According to the present invention, the dicing tape is expanded after inserting a thin heating wire into the groove between the devices divided by the prior dicing method to form a break starting point in the adhesive film for die bonding exposed at the groove bottom. The die bonding adhesive tape can be easily broken from the starting point along the wafer splitting line, and the die bonding adhesive film is attached to the back surface of the wafer that has been subjected to the dividing process by the first dicing method. You can get a device.

  In addition, the die bonding adhesive film can be more reliably broken by cooling the die bonding adhesive film in the die bonding adhesive film breaking step.

It is a surface side perspective view of a semiconductor wafer. FIG. 2A is an explanatory view of a cutting groove forming step, and FIG. 2B is a cross-sectional view of a semiconductor wafer on which cutting grooves are formed. It is the surface side perspective view of the semiconductor wafer in which the cutting groove was formed. It is a perspective view which shows a mode that a laser processing groove | channel is formed by irradiation of a pulse laser beam. FIG. 5A is a perspective view showing a state where a protective tape is attached to the surface of the semiconductor wafer, and FIG. 5B is a perspective view of a state where the protective tape is attached to the surface of the semiconductor wafer. 6A is an explanatory diagram of a cutting groove exposing step for grinding the back surface of the semiconductor wafer, FIG. 6B is a cross-sectional view of the state in which the cutting groove is exposed on the back surface of the semiconductor wafer by grinding, FIG. C) is a perspective view of the semiconductor wafer in a state in which cutting grooves are exposed on the back surface of the semiconductor wafer. FIG. 7A is a perspective view showing a state in which the DAF is disposed on the back surface of the semiconductor wafer, and FIG. 7B is a perspective view in a state in which the DAF is disposed on the back surface of the semiconductor wafer. FIG. 8A is a perspective view showing a state in which the DAF side of the semiconductor wafer is attached to a dicing tape whose outer peripheral portion is attached to the annular frame, and FIG. 8B is a dicing tape whose outer peripheral portion is attached to the annular frame. FIG. 3 is a perspective view of a state in which the DAF side of the semiconductor wafer is attached to the semiconductor wafer. FIG. 9A is a perspective view showing a state in which the back surface of the semiconductor wafer is attached to a DAF-attached dicing tape whose outer peripheral portion is attached to an annular frame, and FIG. 9B is similar to FIG. 8B. FIG. 3 is a perspective view of a state in which a semiconductor wafer with DAF is supported by an annular frame via a dicing tape. It is a perspective view which shows a mode that a protective tape is peeled from the surface of a semiconductor wafer. It is a perspective view of a braking device. It is explanatory drawing of a DAF fracture | rupture process. FIG. 13 is an enlarged view of a portion A in FIG.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Referring to FIG. 1, a front side perspective view of a semiconductor wafer 2 is shown. The semiconductor wafer 2 is made of, for example, a silicon wafer having a thickness of 700 μm, and a plurality of division lines (streets) 4 are formed in a lattice shape on the surface 2a. On the surface 2 a of the semiconductor wafer 2, devices 6 such as ICs and LSIs are formed in respective regions partitioned by a plurality of division lines 4 formed in a lattice shape.

  In the method of manufacturing a semiconductor device according to the embodiment of the present invention, first, a dividing step of dividing the semiconductor wafer 2 into individual semiconductor devices 6 along the division planned line 4 is performed. In the following description, an embodiment will be described in which this division step is performed by the prior dicing method.

  In this tip dicing method, a cutting groove forming step is first performed. That is, a cutting groove having a predetermined depth (a depth corresponding to the finished thickness of each device) is formed along the planned division line formed on the surface 2 a of the wafer 2.

  This cutting groove forming step is performed using a cutting apparatus 10 shown in FIG. The cutting apparatus 10 shown in FIG. 2A includes a chuck table 8 that includes suction holding means and is movable in the X-axis direction, a cutting unit 12, and moves integrally with the cutting unit 12 in the Y-axis direction and the Z-axis direction. A possible alignment unit 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 such as a CCD camera.

  In order to carry out the cutting groove forming step, the semiconductor wafer 2 is placed on the chuck table 8 with its surface 2a facing up. Then, the wafer 2 is held on the chuck table 8 by operating a suction means (not shown).

  In this way, the chuck table 8 that sucks and holds the wafer 2 is positioned directly below the imaging means 20 by a cutting feed mechanism (not shown). When the chuck table 8 is positioned immediately below the image pickup means 20, an alignment operation for detecting a cutting region in which a cutting groove is to be formed in the wafer 2 is performed by the image pickup means 20 and a control means (not shown).

  That is, the imaging unit 20 and a control unit (not shown) execute image processing such as pattern matching for aligning the division line 4 formed in the first direction of the wafer 2 with the cutting blade 18. Execute alignment of the cutting area. Further, the alignment of the cutting area is performed in the same manner for the division line 4 formed in the wafer 2 and extending in the second direction perpendicular to the first direction.

  After such alignment, the chuck table 8 holding the wafer 2 is moved to the cutting start position in the cutting area. Then, the cutting blade 18 moves downward while rotating in the direction indicated by the arrow 21 in FIG. This cutting feed amount is set such that the outer peripheral edge of the cutting blade 18 is at a depth position (for example, 50 μm) corresponding to the finished thickness of the device from the surface 2 a of the wafer 2.

  When the cutting blade 18 is cut and fed in this way, the chuck table 8 is cut and fed in the X-axis direction, that is, in the direction indicated by the arrow X1 in FIG. As shown in FIG. 2B, a cutting groove 22 having a depth (for example, 50 μm) corresponding to the finished thickness of the device is formed along the planned dividing line 4 (cutting groove forming step). This cutting groove forming step is performed along all the division lines 4 formed on the wafer 2. FIG. 3 shows a top perspective view of the wafer 2 obtained as a result.

  Instead of forming the above-mentioned cutting groove, a laser beam may be formed on the surface 2a of the wafer 2 by irradiating a laser beam along a planned division line. The formation of the laser processing groove is performed using a laser beam irradiation means 40 of a laser processing apparatus as shown in FIG.

  The laser beam irradiation means 40 has a cylindrical casing 42. In the casing 42, a pulse laser beam oscillation means including a pulse laser beam oscillator such as a YAG laser oscillator or a YVO4 laser oscillator and a repetition frequency setting means is disposed.

  A condenser 44 for condensing the pulse laser beam oscillated from the pulse laser beam oscillating means is attached to the tip of the casing 42. Reference numeral 46 denotes an alignment unit that detects a processing region, and includes an imaging unit 48. The imaging means 48 includes, for example, a CCD camera and a microscope.

  Image processing such as pattern matching for imaging the processing region of the wafer 2 with the imaging unit 48 and aligning the condenser 44 of the laser beam irradiation unit 40 with the street 4 is executed by the alignment unit 46. Beam irradiation position alignment is performed.

  When the street 4 of the wafer 2 held on the chuck table 8 is detected in this way and the alignment of the laser beam irradiation position is performed, the condenser 44 that irradiates the chuck table 8 with the laser beam is provided. The chuck table 8 is moved in the X1 direction at a predetermined feed rate (for example, 100 mm / second) while moving to the laser beam irradiation area and irradiating the laser beam from the condenser 44 along the street 4 of the wafer 2. Then, a laser processing groove 50 is formed on the surface 2 a of the wafer 2. The depth of the laser processing groove 50 is set to a depth (for example, 50 μm) corresponding to the finished thickness of the device.

  The laser processing conditions are as follows, for example.

Light source: YAG pulse laser Wavelength: 355 nm (third harmonic of YAG laser)
Output: 3.0W
Repetition frequency: 20 kHz
Condensing spot diameter: 1.0 μm
Feeding speed: 100 mm / second

  After the end of the cutting groove forming process or after the end of the laser processing groove forming process described with reference to FIG. 4, the surface 2a of the semiconductor wafer 2 (the surface on which the device 6 is formed) as shown in FIG. A protective tape 24 for grinding is attached.

  As the protective tape 24, for example, a polyolefin tape having a thickness of 150 μm is used. A perspective view of a state in which the protective tape 24 is adhered to the surface 2a of the wafer 2 is shown in FIG.

  Next, the back surface 2b of the wafer 2 having the protective tape 24 attached to the front surface is ground, and the cutting groove exposing process is performed in which the cutting groove 22 is exposed on the back surface 2b and the wafer 2 is divided into individual devices 6. .

  As shown in FIG. 6A, the cutting groove exposing step is performed by a grinding device 26 including a chuck table 28 and a grinding unit 30. The grinding unit 30 includes a mounter 32 fixed to the tip of a spindle 33 and a grinding wheel 36 fixed to the mounter 32 with bolts 34.

  In this cutting groove exposing step, the back surface 2b of the wafer 2 is held on the chuck table 28. For example, while rotating the chuck table 28 in the direction indicated by the arrow 29 at 300 rpm, the grinding wheel 36 is indicated by the arrow 31. Rotating at 6000 rpm in the direction shown, the grinding wheel 36 is brought into contact with the back surface 2b of the wafer 2 to grind the back surface 2b of the wafer 2. This grinding is performed until the cutting groove 22 appears on the back surface 2b of the wafer 2 as shown in FIG.

  By grinding until the cutting groove 22 is exposed in this way, the wafer 2 is divided into individual devices 6 as shown in FIG. In addition, since the protective tape 24 is affixed on the surface 2a of the plurality of divided devices 6, the form of the wafer 2 is maintained without being separated.

  After the back surface of the wafer 2 is ground and the wafer 2 is divided into individual devices 6, a DAF (Die Attach Film) 38, which is a die bonding adhesive film, is disposed on the back surface 2b of the wafer 2 as shown in FIG. . Next, as shown in FIG. 8, the DAF 38 side of the wafer 2 is attached to a ductile dicing tape T having an outer peripheral portion attached to the annular frame F.

  The DAF 38 is not limited to the single DAF shown in FIG. 7A, and a dicing tape integrated DAF 38 as shown in FIG. 9A can also be used. In this case, the back surface of the wafer 2 is adhered to the DAF 38 of the DAF integrated dicing tape T whose outer peripheral portion is adhered to the annular frame F.

  If the wafer 2 having the DAF 38 disposed on the back surface thereof is supported by the annular frame F via the dicing tape T, the protective tape 24 is peeled off from the surface 2a of the wafer 2 as shown in FIG. Next, a DAF breaking step of breaking the DAF 38 along the planned dividing line 4 is performed using the braking device 60 shown in FIG.

  The braking device 60 shown in FIG. 11 includes a frame holding means 62 that holds the annular frame F, and a tape extending means 64 that extends the dicing tape T attached to the annular frame F held by the frame holding means 62. ing.

  The frame holding means 62 includes an annular frame holding member 66 and a plurality of clamps 68 as fixing means arranged on the outer periphery of the frame holding member 66. An upper surface of the frame holding member 66 forms a mounting surface 66a on which the annular frame F is mounted, and the annular frame F is mounted on the mounting surface 66a.

  The annular frame F placed on the placement surface 66 a is fixed to the frame holding member 66 by a clamp 68. The frame holding means 62 configured as described above is supported by the tape extending means 64 so as to be movable in the vertical direction.

  The tape expansion means 64 includes an expansion drum 70 disposed inside the annular frame holding member 66. The expansion drum 70 has an inner diameter 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 70 has a support flange 72 formed integrally with the lower end thereof. The tape expanding means 64 further includes driving means 74 that moves the annular frame holding member 66 in the vertical direction. The driving means 74 is composed of a plurality of air cylinders 76 disposed on the support flange 72, and the piston rod 78 is connected to the lower surface of the frame holding member 66.

  The drive means 74 composed of a plurality of air cylinders 76 has an annular frame holding member 66 with a predetermined amount from the reference position where the mounting surface 66a is substantially flush with the upper end of the expansion drum 70 and the upper end of the expansion drum 70. Move vertically between lower expansion positions.

  The braking device 60 further includes cooling means 80 for cooling the DAF 38 attached to the back surface of the semiconductor wafer 2. As shown in FIG. 12, the cooling means 80 includes a support column 82 disposed in the expansion drum 70. A support plate 84 is attached to the upper end of the support column 82, a cooling element 86 such as a Peltier element is disposed on the support plate 84, and the cooling element 86 is covered with a cooling plate 88.

  A DAF breaking step performed using the braking device 60 configured as described above will be described with reference to FIGS. As shown in FIG. 12A, the annular frame F that supports the semiconductor wafer 2 with the DAF 38 attached to the back surface thereof is supported via the dicing tape T, and is placed on the placement surface 66a of the frame holding member 66. The annular frame F is fixed to the frame holding member 66 by the clamp 68. At this time, the frame holding member 66 is positioned at a reference position where the placement surface 66 a is substantially the same height as the upper end of the expansion drum 70.

  In this state, as shown in FIG. 13 which is an enlarged view of a portion A in FIG. 12, the heating wire 90 heated to a predetermined temperature is inserted into the cutting groove 22, and the heating wire is applied to the DAF 38 exposed at the bottom of the groove 22. 90 is brought into contact to melt the vicinity of the surface of the DAF 38 to form a fracture base 92 in the DAF 38. The diameter of the heating wire 90 needs to be thick enough to be inserted into the groove 22. The heating temperature of the heating wire 90 is preferably in the range of 80 ° C to 300 ° C.

  In FIG. 13, only one heating wire 90 for forming the break starting point 92 is shown, but a heating wire unit having a plurality of heating wires 90 spaced apart by a predetermined pitch is used to improve work efficiency. In addition, it is preferable to form the fracture starting point 92 in the DAF 38 exposed at the bottom of the plurality of cutting grooves 22 at a time.

  If the width of the cutting groove 22 is too narrow to insert the heating wire 90, a pre-expansion step of driving the air cylinder 76 to lower the frame holding member 66 and expanding the dicing tape T in the radial direction is performed. carry out. This pre-expansion step expands the width of the groove 22 between the devices 6 and 6 so that the heating wire 90 can be easily inserted into the groove 22.

  After the pre-expansion step, the air cylinder 76 is further driven to lower the frame holding member 66 to the extended position shown in FIG. As a result, the annular frame F fixed on the mounting surface 66a of the frame holding member 66 is also lowered, so that the DAF 38 attached to the annular frame F abuts on the upper edge of the cooling plate 88 and mainly in the radial direction. Expanded.

  As a result, tensile force acts radially on the DAF 38 attached to the dicing tape T. When a tensile force is applied to the DAF 38 in a radial manner in this manner, the DAF 38 is formed with a break starting point 92. Therefore, the DAF 38 is broken from the break starting point along the division line 4 and the DAF 38 is adhered to the back surface. The device 6 can be obtained.

  The DAF breaking step is preferably performed while the cooling means 80 is operated and the DAF 38 is cooled. This is because when DAF 38 is cooled to 10 ° C. or less, its stretchability is lowered and it is easily broken.

2 Semiconductor wafer 6 Device 10 Cutting device 18 Cutting blade 22 Cutting groove 24 Protective tape 26 Grinding device 36 Grinding wheel 38 DAF
50 Laser processing groove 60 Braking device 62 Frame holding means 64 Tape expanding means 80 Cooling means 86 Cooling element T Dicing tape F Annular frame

Claims (5)

A method of manufacturing a semiconductor device in which an adhesive film for die bonding is disposed on the back surface,
A wafer in which a device is formed in each region partitioned by a predetermined division line provided in a lattice shape on the surface is formed with a depth corresponding to the finished thickness of the device from the surface side along the predetermined division line. Forming grooves,
A protective tape is attached to the surface of the wafer in which the groove is formed,
Grinding the backside of the wafer to which the protective tape has been applied to the finished thickness of the device, exposing the grooves from the backside to divide the wafer into individual devices,
A die bonding adhesive film is arranged on the back side of the wafer divided into individual devices,
Adhering the adhesive film for die bonding to a ductile dicing tape whose outer periphery is attached to an annular frame,
Peel off the protective tape attached to the wafer surface,
A heating wire having a thickness that can be inserted into the groove heated to a predetermined temperature is inserted into the groove of the wafer supported by the dicing tape, and the electric wire is applied to the die bonding adhesive film exposed at the bottom of the groove. Contact the heat ray to melt the vicinity of the surface of the adhesive film for die bonding, forming a break starting point in the adhesive film for die bonding,
Expanding the dicing tape attached to the annular frame to break the die bonding adhesive film from the break starting point along the division line;
A method of manufacturing a semiconductor device, comprising each step.   The semiconductor device manufacturing method according to claim 1, further comprising a pre-expansion step of expanding the dicing tape on which the wafer is mounted until the groove has a width wider than the diameter of the heating wire before forming the break starting point. Method.   3. The method of manufacturing a semiconductor device according to claim 1, wherein the step of breaking the die bonding adhesive film from the break starting point is performed while cooling the dicing tape to which the die bonding adhesive film is attached.   The method for manufacturing a semiconductor device according to claim 1, wherein a temperature for heating the heating wire is in a range of 80 ° C. to 300 ° C. 5.   The method for manufacturing a semiconductor device according to claim 1, wherein the step of forming a groove having a depth corresponding to the finished thickness of the device is performed by irradiation with a pulsed laser beam.

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