TW201541508A - Processing method - Google Patents

Abstract

To provide a processing method capable of reliably segmenting DAF (Die Attach Film) in correspondence to devices one by one. A processing method to segment, corresponding to one device by one device, the DAF attached on a wafer backside, wherein the wafer is formed with a plurality of devices divided by lattice-like scribing lines, characterized in that the processing method comprises: a wafer preparation step of preparing a wafer with a modified layer formed therein along the scribing lines, or a wafer having a plurality of devices already divided along the scribing lines; a wafer configuration step of positioning the wafer prepared in the wafer preparation step on an annular ring frame having an opening portion for receiving the wafer, and disposing the wafer backside on an expansion tape through the DAF; and a DAF segmentation step. After the wafer configuration step, the expansion tape is expanded through the DAF tape to apply a tensile force to the wafer for widening the space between adjacent devices, and the DAF is segmented in a manner of corresponding to the devices. Furthermore, in the DAF segmentation step, the DAF is softened by being heated to a predetermined temperature.

Description

processing methods Field of invention

The present invention relates to a processing method, and more particularly to a processing method for dividing a DAF attached to a back surface of a wafer in accordance with a device.

Background of the invention

In a semiconductor device manufacturing process, a semiconductor wafer (hereinafter, simply referred to as a wafer) in which a plurality of devices such as ICs and LSIs are formed on the surface is divided into individual devices to form a semiconductor device.

The divided semiconductor device is bonded (subjected) to a metal substrate (lead frame), a tape substrate, or the like by wafer bonding, and the metal substrate or the tape substrate is divided and manufactured. One semiconductor wafer. The semiconductor wafer thus manufactured is widely used in electronic devices such as mobile phones and computers.

In order to bond a semiconductor device to a substrate by wafer bonding, an adhesive such as solder or an Au-Si eutectic or a resin paste is supplied to a semiconductor device mounting position on a substrate, and a semiconductor device is placed thereon. And then the method.

In recent years, for example, Japanese Patent Laid-Open No. Hei 11-219962 As disclosed, a method of subsequently bonding a thin film called a DAF (wafer bonding film) on the back side of a semiconductor wafer has been widely employed.

That is, a semiconductor wafer having a wafer-bonding film on its back surface is divided into individual devices to form a semiconductor device in which a film is attached on the back surface. Thereafter, by performing wafer bonding on the substrate through the DAF on the back surface of the semiconductor device, there is an advantage that the adhesive used can be minimized and the loading region of the semiconductor device can be minimized.

On the other hand, in recent years, electric devices such as mobile phones and computers have been demanding to be lighter and smaller, and to require thinner devices. As a technique for dividing a wafer into a thinner device, a technique called a so-called post-cutting polishing method has been developed and put into practical use (see, for example, Japanese Laid-Open Patent Publication No. Hei 11-40520).

The first dicing method is a dividing groove which is formed from a surface of a semiconductor wafer along a predetermined dividing line to a predetermined depth (corresponding to a depth of a finished product thickness of the device), and thereafter, a semiconductor wafer having a dividing groove formed on the surface thereof The back surface is ground to expose the dividing groove to the back surface and divided into individual devices, and the thickness of the device can be processed to 100 μm or less.

Further, in the laser processing method of the wafer, a known method is to position a condensing point of a laser beam having a wavelength (for example, 1064 nm) having a penetrating property to the wafer inside the wafer corresponding to the dividing line. The laser beam is irradiated along the planned dividing line to form a modified layer inside the wafer, and then an external force is applied to divide the wafer into individual devices (see, for example, Japanese Patent No. 3408805).

However, using this method to form a modified layer inside the wafer, and further After attaching the DAF to the back side of the wafer, the method of applying an external force to the wafer to divide it into individual devices has a problem that it is difficult to cut the DAF while dividing the wafer.

As a method for solving this problem, Japanese Patent Laid-Open Publication No. 2007-27250 discloses a technique in which a wafer is divided into individual devices by a first dicing and polishing method, or along a dividing line. The back surface of the wafer on which the modified layer is formed inside the wafer is attached with an expanded tape through the DAF, and the expansion tape is expanded to widen the interval between the device and the device, and the DAF is corresponding to the device. And the technique of dividing.

Prior technical literature Patent literature

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

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

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

Summary of invention

However, in the method of dividing the DAF disclosed in Patent Document 3, although the DAF can be cooled to lower the endurance or the acceleration is added to the expansion of the expansion tape to increase the division force, it is difficult to correspond to the DAF. The problem that the devices are indeed segmented.

The present invention has been made in view of such problems, and an object thereof is to provide a process capable of reliably dividing a DAF corresponding to a single device. method.

According to the processing method of the present invention, the DAF attached to the back surface of the wafer on which a plurality of devices arranged by the predetermined dividing line forming the grid are formed is formed, and the processing method is performed corresponding to the individual devices. The processing method includes: a wafer preparation step of preparing a wafer having a modified layer formed along a planned dividing line inside the wafer, or dividing into a plurality of devices along a dividing line a wafer in which the wafer prepared in the wafer preparation step is positioned on an annular frame having an opening for accommodating the wafer, and the back surface of the wafer is placed on the expansion tape through the DAF; In the DAF division process, after the wafer placement process is performed, the expansion tape is expanded to transmit the tensile force to the wafer through the DAF, the interval between adjacent devices is widened, and the DAF is divided corresponding to the device, and further, in the DAF In the dividing step, the DAF is heated to a predetermined temperature to soften it.

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

According to the present invention, since the expansion tape is expanded after the DAF is heated, the DAF located between the device and the device can be expanded in accordance with the expansion of the expansion tape, and the DAF can be surely divided correspondingly to the individual devices.

2‧‧‧Cutting unit

4, 14‧‧‧ shaft

6‧‧‧Cutting inserts

8‧‧‧Cutting trench

10, 26‧‧‧ chuck table

11‧‧‧Semiconductor wafer

11a‧‧‧ surface

11b‧‧‧Back

12‧‧‧ grinding unit

13‧‧‧Division line

15‧‧‧ device

16‧‧‧ wheel seat

17‧‧‧Protection tape

18‧‧‧ grinding wheel

19‧‧‧Modified layer

20‧‧‧ screws

21‧‧‧DAF

22‧‧‧ wheel abutment

23‧‧‧ Wafer Unit

24‧‧‧ grinding grinding stone

28‧‧‧ concentrator

30‧‧‧Segmentation equipment

32‧‧‧Framework means

34‧‧‧ Tape expansion means

36‧‧‧Frame holding components

36a‧‧‧Loading surface

38‧‧‧ clamp

40‧‧‧Expanding drum

42‧‧‧Support flange

44‧‧‧ Driving means

46‧‧‧ cylinder

48‧‧‧ piston rod

50‧‧‧heating station

F‧‧‧Ring frame

T1‧‧‧Expanding tape

X1, A, a, b‧‧‧ arrows

1 is a perspective view of a surface side of a semiconductor wafer.

Fig. 2 is a perspective view showing a cutting process in the first cutting and grinding method.

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

4(A) and 4(B) are perspective views showing the dividing process.

Fig. 5 is a perspective view showing a process of forming a reforming layer.

6(A) and 6(B) are cross-sectional views showing a step of forming a reforming layer.

FIG. 7 is a perspective view illustrating a wafer disposing process in which a wafer is placed on an expanded tape by DAF.

Figure 8 is a perspective view of the split device.

9(A) and 9(B) are partial cross-sectional side views showing the DAF dividing step.

Form for implementing the invention

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 (hereinafter, simply referred to as a wafer) 11 is shown.

On the surface 11a of the wafer 11, a plurality of predetermined dividing lines (cutting lines) 13 are formed in a lattice shape, and devices 15 such as ICs and LSIs are formed in respective areas partitioned by the dividing planned line 13. 11b is the wafer 11 The back. The wafer 11 can be, for example, a germanium wafer having a thickness of about 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 step is an embodiment in which a wafer is divided into individual devices by a dicing and polishing method, and the wafer is divided into wafers of individual devices, and reference is made to the drawings. 2 to 4 are explained.

In the first cutting and grinding method, a cutting process is performed, and the cutting is performed. The cutting step is to suck the holding back surface 11b side of the wafer 11 by a chuck table of a cutting device not shown, and as shown in FIGS. 2 and 3, the cutting insert 6 is attached to the front end of the rotating shaft 4 of the cutting unit 2. The surface 11a of the wafer 11 is cut along the dividing line 13 to form a cutting groove 8 having a thickness of the finished wafer 11 (the depth of the groove is about 100 μm or so).

In the cutting step, the chuck table 6 that sucks and holds the wafer 11 is processed and conveyed in the direction of the arrow X1 in FIG. 2, and the cutting blade 6 is rotated at a high speed (for example, 30,000 rpm) in the direction of the arrow A. The dividing line 13 extending in the one direction cuts into the surface 11a of the wafer 11 to form a cutting groove 8 which is deeper than the finished thickness of the wafer 11.

The cutting inserts 6 are conveyed in accordance with the pitch of each of the dividing lines 13 to cut all the dividing lines 13 extending in the first direction to form the same cutting grooves 8. Next, after the chuck table (not shown) that has held the wafer 11 is rotated by 90°, the same cutting groove 8 is formed along the planned dividing line 13 extending in the second direction orthogonal to the first direction.

After the cutting process is performed, a dividing step of grinding the back surface 11b of the wafer 11 to thin the wafer 11 to the finished thickness and exposing the cutting groove 8 to the back surface 11b of the wafer 11 may be performed. The wafer 11 is divided into individual device wafers 15.

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

The grinding unit 12 of the grinding device comprises a motor driven rotation The rotating shaft 14, the wheel base 16 fixed to the front end of the rotating shaft 14, and the grinding wheel 18 fixed to the wheel base 16 by a plurality of screws 20 are detachably fixed. The grinding wheel 18 is composed of an annular wheel base 22 and a plurality of grinding stones 24 that are fixed in a ring shape at the outer peripheral portion of the lower end of the wheel base 22 .

In the dividing step, the chuck table 10 is rotated at a direction of, for example, 300 rpm in the direction of the arrow a, and the grinding wheel 18 is rotated in the same direction as the chuck table 10, that is, the direction of the arrow b, for example, at 6000 rpm. Further, the grinding unit conveying mechanism, not shown, is actuated to cause the grinding stone 24 to contact the back surface 11b of the wafer 11.

Then, the grinding wheel 18 is ground to a predetermined amount by a predetermined grinding transmission speed to perform grinding of the wafer 11. When the wafer 11 is continuously thinned to a finished thickness (for example, 90 μm), as shown in FIG. 4(B), the cutting groove 8 is exposed on the back surface 11b of the wafer 11, and the wafer 11 is divided into Device wafers 15 one by one.

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

In the reforming layer forming step, the condensing point of the laser beam having a wavelength (for example, 1064 nm) having a penetrating property to the wafer 11 is positioned inside the wafer 11 corresponding to the dividing line 13 to face the arrow. The chuck stage 26 is moved in the X1 direction, and the reforming layer 19 is formed inside the wafer 11 while irradiating the laser beam along the dividing line 13 .

As shown in FIG. 6(B), when the laser beam is irradiated from the concentrator 28 Upon reaching the end of the wafer 11, the irradiation of the laser beam is stopped, and the processing transfer of the chuck table 26 is stopped.

The wafer 11 is transferred in accordance with the pitch of each of the division planned lines 13 to form the reforming layer 19 inside the wafer along the dividing line 13 extending in the first direction. Next, the chuck table 26 is rotated 90. Thereafter, the same modified layer 19 is formed inside the wafer along all the planned dividing lines 13 extending in the second direction orthogonal to the first direction.

As described above, in the wafer preparation step of the second embodiment, the wafer 11 in which the modified layer 19 is formed inside the wafer along the planned dividing line 13 can be prepared.

After the wafer preparation process is performed, as shown in FIG. 7, a wafer arrangement step of positioning the wafer 11 on the annular frame F having the opening for accommodating the wafer 11 may be performed. The wafer 11 is placed on the expansion tape T1 through the DAF 21 attached to the back surface of the wafer 11. The expansion tape T1 is a DAF-attached expansion tape in which the DAF 21 is formed in advance, and the outer peripheral portion thereof is attached to the annular frame F to form the wafer unit 23.

In the wafer unit 23, the wafer 11 to which the DAF 21 is attached on the back surface is supported by the annular frame F through the expansion tape T1. The wafer 11 shown in FIG. 7 is a wafer 11 of the device 15 which is divided into individual devices by a dicing and post-grinding method, and the protective tape 17 which has been attached to the surface 11a of the wafer 11 at the time of the dividing process is shown. The state shown in 7 is stripped.

The wafer 11 of the wafer unit 23 shown in FIG. 7 is divided into the wafers of the devices 15 by the first cutting and polishing method, but may be the wafers described in the wafer preparation process. Internal along the dividing line A wafer of the second embodiment having the modified layer 19 is formed.

After the wafer arranging step is performed, a DAF dividing step of expanding the expansion tape T1 and applying a tensile force to the wafer 11 to widen the interval between the adjacent devices 15 and corresponding to the DAF 21 can be performed. The device 15 is divided. In this division process, for example, the division device 30 as shown in Fig. 8 is used.

The dividing device 30 shown in FIG. 8 includes a frame holding means 32 for holding the annular frame F, and a tape expanding means 34 for expanding the expansion tape T1 held by the annular frame F held by the frame holding means 32.

The frame holding means 32 is composed of an annular frame holding member 36 and a plurality of clamps 38 disposed as fixing means disposed on the outer circumference of the frame holding member 36. A mounting surface 36a on which the annular frame F is placed is formed on the upper surface of the frame holding member 36, and the annular frame F can be placed on the mounting surface 36a.

Further, the annular frame F placed on the placing surface 36a is fixed to the frame holding member 36 by the clamp 38. The frame holding means 32 thus constituted is supported by the tape expanding means 34 so as to be movable in the vertical direction.

The tape expanding means 34 is provided with an expanding drum 40 disposed inside the annular frame holding member 36. The expansion drum 40 has an inner diameter smaller than the inner diameter of the annular frame F and larger than the outer diameter of the semiconductor wafer 11 attached to the expansion tape T1 of the annular frame F.

The expansion drum 40 has a support flange 42 formed integrally at its lower end. The tape expanding means 34 further includes a driving means 44 for moving the annular frame holding member 36 in the vertical direction. This driving means 44 is configured by A plurality of cylinders 46 on the flange 42 are supported and the piston rod 48 is coupled to the lower surface of the frame holding member 36.

The driving means 44 composed of a plurality of cylinders 46 allows the annular frame holding member 36 to be vertically positioned at a reference position at which the mounting surface 36a and the upper end of the expanding drum 40 are substantially at the same height, and the distance expanding drum The upper end of 40 moves between the expanded positions below the predetermined amount.

The dividing means 30 further has a heating stage 50 disposed inside the expanding drum 40. The heating stage 50 is provided with a Peltier element or the like in its interior, and can control the surface temperature of the heating stage 50 by controlling the applied current. The heating stage 50 is movable in the up and down direction by a driving means not shown.

The division process performed using the division device 30 configured as described above will be described with reference to FIGS. 9(A) and 9(B). As shown in FIG. 9(A), the annular frame F supporting the wafer 11 to which the DAF 21 is attached via the expansion tape T1 is placed on the mounting surface 36a of the frame holding member 36, 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 where the mounting surface 36a and the upper end of the expansion drum 40 are substantially the same height.

In this state, the heating stage 50 is raised and brought into contact with the expansion tape T1, and the DAF 21 attached to the back surface of the wafer 11 is heated by the expansion tape T1. Preferably, the DAF 21 is heated by the heating stage 50 to a temperature in the range of 50 ° C to 150 ° C. By this heating, the DAF 21 is softened and becomes in a state of being easily broken.

When the DAF 21 is sufficiently heated to a predetermined temperature, the heating stage 50 can be lowered. Then, the cylinder 46 is driven to lower the frame holding member 36 to The expanded position shown in Fig. 9(B). Thereby, since the annular frame F fixed to the mounting surface 36a of the frame holding member 36 is also lowered, the expansion tape T1 attached to the annular frame F abuts against the upper end edge of the expansion drum 40. Expand in the radial direction.

As a result, the tensile force acts radially on the DAF 21 and the wafer 11 attached to the expansion tape T1. When the tensile force is radially applied to the wafer 11 and the DAF 21 as such, the wafer 11 will widen the interval between the adjacent devices 15 in accordance with the expansion of the expansion tape T1, and because the adjacent device 15 is located. The DAF 21 between them is heated to a predetermined temperature and becomes easily expanded, so that it can be expanded in the radial direction, and the device 16 corresponding to the DAF 21 is surely divided.

In the wafer 11 prepared in the wafer preparation step of the second embodiment described above, since the modified layer 19 is formed along the planned dividing line 13 inside the wafer, when the expanded tape T1 is expanded, the wafer 11 is formed. The dividing line 13 which is reduced in strength along the formation of the reforming layer 19 is divided into individual devices 15, and the DAF 21 is easily expanded due to being heated to a predetermined temperature, so that it can be expanded in the radial direction. The device 15 corresponding to the DAF 21 is surely divided.

11‧‧‧Semiconductor wafer

15‧‧‧ device

21‧‧‧DAF

32‧‧‧Framework means

36‧‧‧Frame holding members

36a‧‧‧Loading surface

38‧‧‧ clamp

40‧‧‧Expanding drum

44‧‧‧ Driving means

46‧‧‧ cylinder

48‧‧‧ piston rod

50‧‧‧heating station

F‧‧‧Ring frame

T1‧‧‧Expanding tape

Claims (2)

A processing method is a processing method in which a DAF attached to a back surface of a wafer on which a plurality of devices arranged by forming a lattice-shaped dividing line are formed on a surface, and which is divided into a plurality of devices, is characterized in that The processing method includes: a wafer preparation process, preparing a wafer having a modified layer formed inside a wafer along a dividing line, or a wafer which has been divided into individual devices along a dividing line; In the disposing step, the wafer prepared in the wafer preparation step is positioned on the annular frame having the opening for accommodating the wafer, and the back surface of the wafer is placed on the expansion tape via the DAF; and the DAF division process is performed. After the wafer arranging step is performed, the expansion tape is expanded to spread the tensile force to the wafer through the DAF, and the interval between the adjacent devices is widened, and the DAF is divided corresponding to the device, and in the DAF division process, The DAF is heated to a predetermined temperature to soften it. The processing method of claim 1, wherein the predetermined temperature is in the range of 50 ° C to 150 ° C.