CN104900506A - Processing method - Google Patents

Abstract

The present invention provides a processing method. The processing method is a method of dividing a DAF pasted on the back surface of a wafer corresponding to each device. The wafer is divided by dividing lines formed in a lattice shape and a plurality of devices are formed on the front surface. It is characterized in that, Including the following steps: wafer preparation process, preparing a wafer with a modified layer formed inside the wafer along the planned dividing line, or a wafer divided into individual devices along the planned dividing line; The wafer prepared in the process is positioned in the ring frame having an opening for accommodating the wafer, and the back surface of the wafer is arranged on the expansion tape through the DAF; The tape expands, a tensile force acts on the wafer through the DAF, and the interval between adjacent devices is enlarged. At the same time, the DAF is divided according to the device. In the DAF dividing step, the DAF is heated to a predetermined temperature to soften the DAF.

Description

processing method

technical field

The present invention relates to a processing method, and particularly relates to a processing method for dividing a DAF bonded on the back surface of a wafer corresponding to devices.

Background technique

In the manufacturing process of semiconductor devices, semiconductor devices are formed by dividing a semiconductor wafer (hereinafter, sometimes simply referred to as a wafer) on which a plurality of devices such as ICs and LSIs are formed on the front surface into individual devices.

The divided semiconductor devices are chip-bonded (bonded) to metal substrates (lead frames) or tape substrates, etc., and these metal substrates or tape substrates are divided to manufacture individual semiconductor chips. The semiconductor chips manufactured in this way are widely used in electronic devices such as mobile phones and computers.

In order to bond the semiconductor device chip to the substrate, a method is used in which an adhesive such as solder, Au-Si eutectic, or resin glue is supplied to the semiconductor device mounting position on the substrate, and the semiconductor device is mounted on the semiconductor device mounting position. Glue in place.

In recent years, a method of adhering an adhesive film called DAF (die adhesive film) in advance on the back surface of a semiconductor wafer as disclosed in, for example, Japanese Patent Application Laid-Open No. 11-219962 has been widely used.

That is, the semiconductor device on which the adhesive film is mounted on the back surface is formed by dividing the semiconductor wafer on which the adhesive film is bonded on the back surface into individual devices. Then, the semiconductor device chip is bonded to the substrate by the DAF on the back surface of the semiconductor device, thereby minimizing the use of an adhesive and minimizing the mounting area of the semiconductor device.

On the other hand, in recent years, electrical equipment such as mobile phones and computers has been required to be lighter and smaller, and thinner devices have been required. As a technique for dividing a wafer into thinner devices, a so-called dicing-before-grinding (Dicing Before Grinding) technique has been developed and put into practical use (for example, refer to Japanese Patent Application Laid-Open No. 11-40520).

The dicing-first method is a technique in which dividing grooves of a predetermined depth (depth corresponding to the finished thickness of the device) are formed along the planned dividing line from the front surface of the semiconductor wafer, and then the semiconductor wafer with the dividing grooves formed on the front surface The back surface is ground to expose the dividing grooves on the back surface, thereby dividing the semiconductor wafer into individual devices. This dicing-first method can process the thickness of the device to 100 μm or less.

Furthermore, in the laser processing method of a wafer, a method is known in which a laser beam of a wavelength (for example, 1064 nm) which is transparent to the wafer is positioned at the inside of the wafer corresponding to the planned dividing line, and along the planned dividing line, A modified layer is formed inside the wafer by irradiating a laser beam, and then the wafer is divided into individual devices by applying an external force (see, for example, Japanese Patent No. 3408805).

However, in this method, a modified layer is formed inside the wafer, DAF is pasted on the back of the wafer, and the wafer is divided into individual devices by applying an external force. In such a method, it is difficult to cut the DAF while dividing the wafer.

As a method for solving this problem, Japanese Patent Application Laid-Open No. 2007-27250 describes a technique in which a reformed layer is formed inside a wafer that is divided into individual devices by a dicing method, or along a planned dividing line. The back surface of the wafer is bonded with an extension tape through the DAF, and the interval between devices is enlarged by expanding the extension tape, and the DAF is divided corresponding to the device.

Patent Document 1: Japanese Patent Application Laid-Open No. 11-219962

Patent Document 2: Japanese Patent Application Laid-Open No. 11-40520

Patent Document 3: Japanese Patent Laid-Open No. 2007-272505

However, in the DAF dividing method disclosed in Patent Document 3, although it is possible to cool the DAF to reduce the resistance or to increase the dividing force by applying acceleration when the expansion band expands, it is still difficult to reliably divide the DAF corresponding to each device. The problem.

Contents of the invention

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a processing method capable of reliably dividing a DAF for each device.

According to the present invention, there is provided a processing method in which a DAF bonded on the back surface of a wafer is divided corresponding to each device. A device, characterized in that the processing method includes the following steps: a wafer preparation step, in which a wafer with a modified layer formed inside the wafer along the planned dividing line is prepared, or a wafer along the planned dividing line is prepared. Wafers that are line-divided into individual devices; a wafer arrangement process, in which the wafer prepared in the wafer preparation process is positioned in a ring frame having an opening for receiving the wafer, and the The back side of the wafer is arranged on the expansion tape; and the DAF dividing process is to expand the expansion tape after implementing the wafer arrangement process, so that the tensile force acts on the wafer through the DAF, so that the interval between adjacent devices is enlarged, At the same time, the DAF is divided according to the device, and in the DAF dividing step, the DAF is heated to a predetermined temperature to soften the DAF. .

Preferably, the predetermined temperature is within the range of 50°C to 150°C.

According to the present invention, since the extended band is expanded after the DAF is heated, the DAF located between devices expands with the expansion of the extended band, and the DAF can be reliably divided for each device.

Description of drawings

FIG. 1 is a front perspective view of a semiconductor wafer.

Fig. 2 is a perspective view showing a cutting step in a cut-first method.

Fig. 3 is an enlarged cross-sectional view illustrating a cutting process.

Fig. 4 is a perspective view showing a dividing step.

Fig. 5 is a perspective view showing a modified layer forming step.

Fig. 6 is a cross-sectional view showing a modified layer forming step.

FIG. 7 is a perspective view illustrating a wafer placement step of placing a wafer on an extended tape via a DAF.

Fig. 8 is a perspective view of a dividing device.

Fig. 9 is a partially cutaway side view showing a DAF dividing step.

Label description

6: cutting tool;

8: cutting groove;

11: semiconductor wafer;

13: split the predetermined line;

15: device;

17: protective belt;

18: grinding wheel;

19: modified layer;

21: DAF;

24: Grinding abrasives;

28: concentrator;

30: Separation device;

32: frame holding member;

34: with expansion member;

40: Expansion cylinder;

50: Heated workbench.

Detailed ways

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Referring to FIG. 1 , there is shown a front perspective view of a semiconductor wafer (hereinafter, sometimes simply referred to as a wafer) 11 .

On the front surface 11a of the semiconductor wafer 11, a plurality of planned dividing lines (segment lanes) 13 are formed in a grid pattern, and devices 15 such as ICs and LSIs are formed in each area divided by the planned dividing lines 13. 11b is a wafer 11 on the back. The wafer 11 is, for example, a silicon wafer with a thickness of approximately 700 μm.

In the processing method of the present invention, first, a wafer preparation step of preparing a wafer to be processed is performed. The first embodiment of the wafer preparation process is an embodiment in which the wafer is divided into individual devices by a dicing-first method to prepare a wafer obtained by dividing the wafer into individual devices, and will be described with reference to FIGS. 2 to 4 .

In this dicing-first method, the back surface 11b side of the wafer 11 is sucked and held by a chuck table of a cutting device not shown, and the following cutting process is performed as shown in FIGS. 2 and 3 : The cutting tool 6 attached to the end of the main shaft 4 of the cutting unit 2 cuts the front surface 11 a of the wafer 11 along the planned dividing line 13 to form a cutting groove 8 (the depth of the groove is about 100 μm) reaching the finished thickness of the wafer 11 .

In the cutting process, while the chuck table holding the wafer 11 by suction is fed along the arrow X1 direction in FIG. The planned dividing line 13 extending in the first direction cuts into the front surface 11 a of the wafer 11 to form a cutting groove 8 reaching the finished thickness of the wafer 11 .

The cutting blade 6 is index-feeded at intervals of the planned dividing lines 13 , and all the planned dividing lines 13 extending in the first direction are cut to form the same cutting grooves 8 . Next, the unshown chuck table holding the wafer 11 by suction is rotated by 90°, and the same cutting groove 8 is formed along the planned dividing line 13 extending in the second direction perpendicular to the first direction.

After implementing the cutting process, implement the dividing step. In the dividing step, the back surface 11b of the wafer 11 is ground, the wafer 11 is thinned to the finished thickness, and the cutting groove 8 is exposed on the back surface 11b of the wafer 11, thereby the wafer 11 is divided into individual device chips 15 .

This division step will be described with reference to FIG. 4 . In the dividing step, as shown in FIG. 4(A), a protective tape 17 is attached to the front surface of the wafer 11, and the front surface 11a side of the wafer 11 is sucked through the protective tape 17 by the chuck table 10 of the grinding device. Hold so that the back surface 11b side of the wafer 11 is exposed.

The grinding unit 12 of the grinding device is composed of the following parts: a main shaft 14 driven by a motor to rotate; a wheel base 16 fixed to the end of the main shaft 14; grinding wheel 18 . The grinding wheel 18 is composed of an annular wheel base 22 and a plurality of grinding tools 24 that are annularly fixed to the outer peripheral portion of the lower end of the wheel base 22 .

In the dividing step, the chuck table 10 is rotated at, for example, 300 rpm in the direction of the arrow a, and the grinding wheel 18 is rotated at, for example, 6000 rpm in the same direction as the chuck table 10, that is, in the direction of the arrow b. The grinding unit feed mechanism operates to bring the grinding stone 24 into contact with the back surface 11 b of the wafer 11 .

Then, the grinding wheel 18 is ground-feeded downward by a predetermined amount at a predetermined grinding feed rate to grind the wafer 11 . When the wafer 11 is thinned to a finished thickness (for example, 90 μm) by continuing grinding, as shown in (B) of FIG. .

Next, a second embodiment of the wafer preparation step will be described with reference to FIGS. 5 and 6 . In the second embodiment, the reformed layer is formed inside the wafer along the planned dividing line 13 of the wafer 11 . FIG. 5 is a perspective view showing a modified layer forming step, and FIG. 6 is a cross-sectional view thereof.

In the reformed layer forming step, the chuck table 26 is moved toward the wafer 11 while the laser beam of a wavelength (for example, 1064 nm) having transmittance to the wafer 11 is positioned at the inside of the wafer 11 corresponding to the planned dividing line 13. While moving in the arrow X1 direction, the laser beam is irradiated along the planned division line 13 to form the reformed layer 19 inside the wafer 11 .

As shown in (B) of FIG. 6 , after the laser beam irradiated from the condenser 28 reaches the end of the wafer 11 , the irradiation of the laser beam is stopped, and the processing feed of the chuck table 26 is also stopped.

The wafer 11 is index-feeded at intervals of the planned dividing lines 13 , and the modified layer 19 is formed inside the wafer along the planned dividing lines 13 extending in the first direction. Next, after the chuck table 26 is rotated by 90°, the same modified layer 19 is formed inside the wafer along the planned dividing line 13 extending in the second direction perpendicular to the first direction.

In this way, in the wafer preparation process of the second embodiment, the wafer 11 in which the reformed layer 19 is formed inside the wafer along the planned dividing line 13 is prepared.

After the wafer preparation process is performed, a wafer arrangement process is performed as shown in FIG. The DAF 21 on the backside of the wafer 11 arranges the wafer 11 on the extension tape T1. The extended tape T1 is an extended tape with a DAF formed in advance with the DAF 21 , and the outer peripheral portion of the extended tape T1 is bonded to the ring frame F to form the wafer unit 23 .

In the wafer unit 23 , the wafer 11 on which the DAF 21 is attached on the back surface is supported by the ring frame F via the expansion tape T1 . The wafer 11 shown in FIG. 7 is divided into individual devices 15 by the dicing-first method, and the protective tape 17 affixed to the front surface 11 a of the wafer 11 in the dividing step is peeled off in the state shown in FIG. 7 .

The wafer 11 of the wafer unit 23 shown in FIG. 7 is a wafer that is divided into individual devices 15 by the dicing method first, but it may also be a modified wafer formed along the dividing line 13 described in the wafer preparation process. Layer 19 of the second embodiment of the wafer.

After the wafer arrangement process is carried out, the DAF division process is implemented. In this DAF division process, the expansion tape T1 is expanded to apply a tensile force to the wafer 11 to expand the interval between adjacent devices 15, and at the same time, the gap between adjacent devices 15 is increased. DAF21 is divided accordingly. In this dividing step, for example, a dividing device 30 shown in FIG. 8 is used.

The dividing device 30 shown in FIG. 8 includes: a frame holding member 32 holding the ring-shaped frame F;

The frame holding member 32 is composed of an annular frame holding member 36 and a plurality of clips 38 as fixing members arranged on the outer periphery of the frame holding member 36 . The upper surface of the frame holding member 36 is formed as a mounting surface 36a on which the ring-shaped frame F is mounted, and the ring-shaped frame F is placed on the mounting surface 36a.

Furthermore, the ring-shaped frame F placed on the mounting surface 36 a is fixed to the frame holding member 36 via the clamp 38 . The frame holding member 32 configured in this way is supported by the belt expansion member 34 so as to be movable in the vertical direction.

The belt expansion member 34 includes an expansion tube 40 disposed inside the annular frame holding member 36 . The expansion cylinder 40 has an inner diameter smaller than the inner diameter of the ring frame F and larger than the outer diameter of the semiconductor wafer 11 attached to the expansion tape T1 attached to the ring frame F. As shown in FIG.

The expansion barrel 40 has a support flange 42 integrally formed at its lower end. The belt expansion member 34 further includes a driving member 44 for moving the annular frame holding member 36 in the vertical direction. The drive member 44 is composed of a plurality of air cylinders 46 arranged on the support flange 42 , and the piston rod 48 thereof is connected to the lower surface of the frame holding member 36 .

The driving member 44 composed of a plurality of air cylinders 46 makes the ring-shaped frame holding member 36 at a reference position substantially at the same height as the upper end of the expansion tube 40 on its mounting surface 36 a in the up-down direction, and closer to the upper end of the expansion tube 40 . Move between expansion positions by the amount specified below.

The split member 30 further includes a heating table 50 disposed inside the expansion cylinder 40 . The heating table 50 incorporates a Peltier element or the like inside, and by controlling the applied current, the surface temperature of the heating table 50 can be controlled. The heating table 50 is movable in the up and down direction by a driving means not shown.

The dividing process performed using the dividing apparatus 30 comprised as mentioned above is demonstrated with reference to FIG. 9(A) and FIG. 9(B). As shown in FIG. 9(A), the ring frame F supporting the wafer 11 on which the DAF 21 is bonded on the back side is placed on the mounting surface 36a of the frame holding member 36 through the expansion tape T1, and is clamped by the clamp 38. The frame holding member 36 is fixed. At this time, the frame holding member 36 is positioned at a reference position at which the mounting surface 36 a is substantially at the same height as the upper end of the expansion cylinder 40 .

In this state, the heating stage 50 is raised to come into contact with the spreading tape T1, and the DAF 21 attached to the back surface of the wafer 11 is heated through the spreading tape T1. Preferably, the DAF 21 is heated to a temperature within a range of 50° C. to 150° C. using the heating stage 50 . By this heating, DAF 21 is softened and is in an easily broken state.

After the DAF 21 is sufficiently heated to a predetermined temperature, the heating table 50 is lowered. Then, the air cylinder 46 is driven to lower the frame holding member 36 to the expanded position shown in (B) of FIG. 9 . As a result, the annular frame F fixed on the mounting surface 36a of the frame holding member 36 also descends, so that the expansion band T1 attached to the annular frame F comes into contact with the upper end edge of the expansion tube 40, and mainly radially expands. up expansion.

As a result, a tensile force acts radially on the DAF 21 and the wafer 11 attached to the expanding tape T1. In this way, when the active force radially acts on the wafer 11 and the DAF 21, in the wafer 11, the interval between adjacent devices 15 expands along with the expansion of the expansion band T1. The DAF 21 is heated to a predetermined temperature and becomes easy to expand. Therefore, the DAF 21 expands in the radial direction, and the DAF 21 is reliably divided corresponding to each device 15 .

In the wafer 11 prepared in the wafer preparation process of the second embodiment described above, since the reformed layer 19 is formed along the planned division line 13 inside the wafer, when the expansion tape T1 is expanded, the wafer 11 is formed along the planned dividing line 13 . The planned dividing line 13 that reduces the strength by modifying the layer 19 is divided into individual devices 15, and since the DAF 21 is heated to a predetermined temperature and easily expands, the DAF 21 expands in the radial direction, and the DAF 21 and the individual devices 15 corresponds to being reliably segmented.

Claims (2)

1. A processing method, the processing method is a processing method of dividing DAF pasted on the back surface of a wafer corresponding to each device, the wafer is divided by dividing lines formed in a lattice shape and a plurality of devices are formed on the front surface, It is characterized in that, The processing method includes the following steps: Wafer preparation process, in this wafer preparation process, preparing the wafer with modified layer formed inside the wafer along the planned dividing line, or the wafer divided into individual devices along the planned dividing line; Wafer placement process, in which the wafer prepared in the wafer preparation process is positioned in a ring frame having an opening for accommodating the wafer, and the rear surface of the wafer is placed on the expansion tape through the DAF ;as well as In the DAF division process, after the wafer arrangement process is performed, the expansion tape is expanded, the tensile force is applied to the wafer through the DAF, the interval between adjacent devices is enlarged, and the DAF is divided corresponding to the device, In the DAF dividing step, the DAF is heated to a predetermined temperature to soften the DAF. 2. processing method according to claim 1, is characterized in that, The prescribed temperature is within the range of 50°C to 150°C.