JP2003077869A5 - - Google Patents

Description

[0005]
[Problems to be solved by the invention]
In order to form extremely small and lightweight semiconductor chips, it is recently desirable to reduce the thickness of the semiconductor wafer by grinding the back surface of the semiconductor wafer, for example, 150 μm or less, especially 50 μm or less. It is not rare that However, if the thickness of a semiconductor wafer made of silicon, for example, is made extremely thin, the rigidity of the semiconductor wafer becomes extremely small, making it difficult to grind without damaging it, and transporting the ground semiconductor wafer at the required speed. It is also extremely difficult to do. In order to prevent the semiconductor wafer from being damaged during grinding, the semiconductor wafer is ground by applying a grinding means to the back surface of the semiconductor wafer with a protective substrate or tape attached to the surface of the semiconductor wafer. You can do it. However, when a protective substrate or a tape is attached to the surface of the semiconductor wafer, in a processing process performed after the back grinding process of the semiconductor wafer, for example, cutting along the street or picking up individually separated rectangular areas However, it is necessary to directly access the semiconductor wafer from its surface, but such access is obstructed by the protective substrate or the protective tape.

In the transfer step, it is preferable that the support substrate is detached from the front surface of the semiconductor wafer after the back surface of the semiconductor wafer is attached to the mounting tape. Preferably, the support substrate is formed from a laminate including a plurality of layers. The laminate includes a high-rigidity layer having a relatively high rigidity and a low-rigidity layer having a relatively low rigidity. The surface of the semiconductor wafer is bonded to the low-rigidity layer side, and the support substrate is attached to the surface of the semiconductor wafer. When releasing, it is preferable to first release the high-rigidity layer and then release the low-rigidity layer. In particular, the support substrate preferably includes a plurality of high-rigidity layers stacked. The high-rigidity layer can be composed of a polyethylene terephthalate sheet or film, and the low-rigidity layer can be composed of a polyolefin sheet or film. The support substrate is larger than the semiconductor wafer, and the periphery of the support substrate preferably extends 1 to 2 mm beyond the periphery of the semiconductor wafer. In a preferred embodiment, the treatment step, the back surface of the semiconductor wafer adsorbed on the chuck means through the mounting tape is cut the semiconductor wafer along the streets by allowed acting cutting means from the surface of the semiconductor wafer cut It is a process. In another preferred embodiment, a groove having a required depth is cut along the street from the surface of the semiconductor wafer mounted on the support substrate. When the semiconductor wafer is ground in the grinding step, the semiconductor wafer Is separated into a number of rectangular regions, and the processing step is a pick-up step of picking up each of the rectangular regions that are individually separated. In the grinding step, the thickness of the semiconductor wafer can be reduced to 150 μm or less.

The support substrate 10 is slightly larger than the semiconductor wafer 2, and the periphery of the support substrate 10 preferably extends beyond the periphery of the semiconductor wafer 2. The overhanging length of the support substrate 10 that extends beyond the periphery of the semiconductor wafer 2 may be about 1 to 2 mm. When the support substrate 10 is disc-shaped and the semiconductor wafer 2 is formed with the straight edge 4, the periphery of the support substrate 10 extends beyond the periphery of the semiconductor wafer 2 by 1 to 2 mm in the portion excluding the straight edge 4. In addition, it is preferable that the protruding length of the peripheral edge of the support substrate 10 is greater than 1 to 2 mm in the portion of the straight edge 4 (in this specification, the protruding length of the peripheral edge of the support substrate 10 is the semiconductor wafer 2. In the case of having a straight edge 4, it means the protruding length of the peripheral edge of the support substrate 10 in a portion other than the straight edge of the semiconductor wafer 2). In the processing of the semiconductor wafer 2, a plurality of semiconductor wafers 2 are accommodated in a cassette (not shown), and more specifically, each of a plurality of accommodation grooves formed at intervals in the vertical direction on the side wall of the cassette. However, when the semiconductor wafer 2 is extremely thin (for example, 50 μm or less), if the periphery of the semiconductor wafer 2 is brought into contact with the bottom surface of the receiving groove, the semiconductor wafer 2 is There is a high risk of being damaged. However, when the peripheral edge of the support substrate 10 on which the semiconductor wafer 2 is mounted extends beyond the peripheral edge of the semiconductor wafer 2, it is ensured that the peripheral edge of the semiconductor wafer 2 directly contacts the bottom surface of the receiving groove. This prevents the semiconductor wafer 2 from being damaged. On the other hand, if the support substrate 10 is excessively large and the peripheral edge thereof excessively protrudes, the support substrate 10 on which the semiconductor wafer 2 is placed cannot be stored in the storage groove of the standard size cassette. Further, when the support substrate 10 is slightly larger than the semiconductor wafer 2 and the periphery of the support substrate 10 extends beyond the periphery of the semiconductor wafer 2, the reason is not necessarily clear, but according to the experiences of the present inventors, chipping on the periphery of the semiconductor wafer 2 is depleted established that occurs when grinding the back surface of the semiconductor wafer 2 to as to be described later, and also from the support base plate 10 and as described below when allowed to leave the semiconductor wafer 2 The disengagement operation becomes much easier.

Next, a grinding process is performed. Referring to FIG. 4, chuck means 16 including a porous chuck plate is used in the grinding process. The chuck means 16 has a somewhat larger outer diameter than the outer diameter of the supporting substrate 10, the semiconductor wafer 2 mounted on the supporting substrate 10 and the upper surface is placed on the chuck means 16. The chuck means 16 is communicated with a vacuum source, whereby the surface of the semiconductor wafer 2 is attracted onto the chuck means 16 via the support substrate 10. Then, the grinding means 18 is applied to the back surface of the semiconductor wafer 2 so that the back surface of the semiconductor wafer 2 is ground, and the thickness of the semiconductor wafer 2 is reduced to a predetermined value. Grinding means 18 may be configured annular grinding tool or found with grinding tool containing diamond particles on its lower surface, chuck means 16 holding the semiconductor wafer 2 when grinding the back surface of the semiconductor wafer 2 its center The grinding means 18 is rotated about its central axis, and the grinding means 18 is pressed against the back surface of the semiconductor wafer 2. In such a grinding process, since the semiconductor wafer 2 is reinforced by the support substrate 10 attached to the surface of the semiconductor wafer 2, the semiconductor wafer 2 can be damaged without causing problems such as damage to the semiconductor wafer 2. 2 can be ground to a thickness of, for example, 150 μm or less, in particular 50 μm or less. Grinding of the back surface of the semiconductor wafer 2 as described above can be conveniently performed by a grinding machine sold under the trade name “DFG841” by DISCO Corporation. When such a grinding machine is used, a plurality of semiconductor wafers 2 mounted on the support substrate 10 are stored in a well-known cassette (not shown) at intervals in the vertical direction for grinding. Can be supplied to the machine.

In the processing method of the present invention, it is important to perform a transfer process following the grinding process. In the transfer process illustrated in FIG. 5, first, the semiconductor wafer 2 is mounted on the frame 22 via the mounting tape 20. The frame 22 is composed of an annular member that can be formed from an appropriate synthetic resin or metal, and a circular mounting opening 24 is formed at the center thereof. The mounting tape 20 can be composed of an appropriate synthetic resin sheet or film, and an adhesive that is advantageously an ultraviolet curable adhesive or a thermosetting adhesive is applied to one side, that is, the lower surface thereof, The pressure sensitive adhesive is attached to one side, that is, the upper surface of the frame 22. As shown in FIG. 5 (a), it is placed on a support base 26 (this support base 26 can be constructed from the chuck means 16 shown in FIG. 4 or from a separate support member). The frame 22 on which the mounting tape 20 is adhered is lowered with respect to the semiconductor wafer 2 being placed, and the semiconductor wafer 2 is positioned in the mounting opening 24 of the frame 22. Then, the lower surface of the mounting tape 20 is attached to the back surface of the semiconductor wafer 2. Next, the support substrate 10, the semiconductor wafer 2, the frame 22, and the mounting tape 20 that are sequentially positioned from the bottom to the top are turned upside down, and the mounting tape 20 and the frame 22 are sequentially stacked from the bottom to the top. Then, the semiconductor wafer 2 and the support substrate 10 are positioned and placed on an appropriate support base 28. Then, the support substrate 10 is irradiated with ultraviolet rays or the support substrate 10 is heated to cure the adhesive existing between the support substrate 10 and the surface of the semiconductor wafer 2 and the adhesive existing between the layers of the support substrate 10. The adhesiveness disappears or decreases. Next, the layers constituting the support substrate 10, that is, the low-rigidity layer 12 and the three high-rigidity layers 14 are sequentially peeled by gradually pulling one edge portion toward the other edge portion. That is, in the state of FIG. 5B, the uppermost high-rigidity layer 14 is first peeled off, then the second high-rigidity layer 14 is peeled off, and the third high-rigidity layer 14 is peeled off. The rigid layer 12 is peeled off , and thus the support substrate 10 is peeled from the surface of the semiconductor wafer 2. Thus, the semiconductor wafer 2 can be changed from a state in which the front surface is attached to the support substrate 10 and attached to the support substrate 10 to a state in which the rear surface is attached to the attachment tape 20 and attached to the frame 22. FIG. 6 shows the semiconductor wafer 2 mounted on the frame 22 via the mounting tape 20 with its surface facing upward.

When the transfer process is completed, a process process is performed in which the semiconductor wafer 2 is accessed from its surface and a required process is performed. In the illustrated embodiment, as shown in FIG. 7, the back surface of the semiconductor wafer 2 is adsorbed onto the chuck means 30 via the mounting tape 20 attached thereto, and the cutting means 32 is attached to the surface of the semiconductor wafer 2. Then, the semiconductor wafer 2 is cut along the streets 6. The chuck means 30 includes a porous chuck plate that communicates with a vacuum source and sucks the back surface of the semiconductor wafer 2 through the mounting tape 20. The cutting means 32 can be conveniently constructed from a thin disk-shaped blade that can be formed by bonding diamond abrasive grains with a suitable binder. The cutting means 32 is centered on its central axis. By relatively moving the chuck means 30 and the cutting means 32 along the streets 6 while rotating at high speed, the rectangular regions 8 can be separated individually by cutting along the streets 6 of the semiconductor wafer 2. . The mounting tape 20 is maintained without being cut. Therefore, even if the rectangular regions 8 are separated individually, the back surface of each rectangular region 8 is stuck to the mounting tape 20 and is held by the frame 22. After performing such a cutting process, the individually separated rectangular regions 8 can be washed and then individually picked up and transported to a required place. The cutting of the semiconductor wafer 2 as described above can be conveniently performed by, for example, a cutting machine (also referred to as a dicer) sold by Disco Corporation under the trade name “DFD641”. Even when such a cutting machine is used, a plurality of semiconductor wafers 2 mounted on the frame 22 via the mounting tape 20 are accommodated in a well-known cassette (not shown) in the vertical direction. Then, it can be supplied to a cutting machine.

[Brief description of the drawings]
[Figure 1]
The slope view which shows the typical example of the semiconductor wafer to which the processing method of this invention is applied .
[Figure 2]
The slope view which shows the state which mounted | wore the support substrate in the mounting process in the processing method of this invention.
[Fig. 3]
The side view which shows the state which mounted | wore the support substrate in the mounting process in the processing method of this invention.
[Fig. 4]
The simplified side view which shows the grinding process in the processing method of this invention.
[Figure 5]
The simplified sectional view showing the transfer process in the processing method of the present invention.
[Fig. 6]
The slope view which shows the state by which the semiconductor wafer is mounted | worn with the mounting tape via the mounting tape after the transfer process in the processing method of this invention.
[Fig. 7]
The simplified sectional view showing the cutting process (processing process) in the processing method of the present invention.
[Explanation of symbols]
2: Semiconductor wafer 6: Street 8: Rectangular area 10: Support substrate 12: Low rigidity layer 14: High rigidity layer 16: Chuck means 18: Grinding means 20: Mounting tape 22: Frame 26: Mounting opening 30: Chuck means 32: Cutting means

Claims (2)

The treatment step, the back surface of the semiconductor wafer adsorbed on the chuck means through the mounting tape, a cutting step of cutting the semiconductor wafer along the streets by allowed acting cutting means from the surface of the semiconductor wafer, according to claim 9. A method for processing a semiconductor wafer according to any one of 1 to 8. Periphery of the support substrate protrudes 1 to 2mm beyond the periphery of the semiconductor wafer, the supporting substrate of a semiconductor wafer according to claim 16, wherein.