JP4074758B2 - Processing method of semiconductor wafer - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention provides a method for processing a semiconductor wafer in which a large number of rectangular regions partitioned by streets arranged in a lattice pattern are arranged on the surface, and each of the rectangular regions is provided with a semiconductor circuit, and such processing The present invention relates to a support substrate used in the method.
[0002]
As is well known to those skilled in the art, in the manufacture of semiconductor devices, a large number of rectangular areas are defined on the surface of a semiconductor wafer by streets arranged in a lattice pattern, and a semiconductor circuit is applied to each of the rectangular areas. Then, the back surface of the semiconductor wafer is ground to reduce its thickness, and the semiconductor wafer is cut along the streets, and the rectangular regions are individually separated to form semiconductor chips.
[0003]
Usually, the grinding means is applied to the back surface of the semiconductor wafer to reduce the thickness of the semiconductor wafer to a required value, and then the cutting means is applied from the surface of the semiconductor wafer to cut the semiconductor wafer along the street. The rectangular areas are separated individually. When cutting a semiconductor wafer along a street, a mounting opening is provided at the center so that the rectangular regions that have been individually separated can be transported and processed after the cutting. It is attached to the frame it has via the attachment tape. More specifically, a tape extending across the mounting opening is mounted on the frame, and the back surface of the semiconductor wafer is attached to the mounting tape in the mounting opening, thus mounting the semiconductor wafer on the frame. Next, the individually separated rectangular regions, that is, semiconductor chips are picked up and transported to a required place.
[0004]
Recently, first, a cutting means is applied from the surface of the semiconductor wafer to form a groove having a required depth along the street, and then a grinding means is applied to the back surface of the semiconductor wafer to obtain the thickness of the semiconductor wafer. It is also practiced to reduce each of the rectangular areas due to the presence of the grooves. Also in this case, when grinding the back surface of the semiconductor wafer, a mounting opening is provided in the center portion so that the rectangular regions separated individually can be transported and cleaned. It is attached to the frame via attachment tape. More specifically, a tape extending across the mounting opening is mounted on the frame, and the surface of the semiconductor wafer is attached to the mounting tape in the mounting opening, thus mounting the semiconductor wafer on the frame. Next, the individually separated rectangular regions, that is, semiconductor chips are picked up and transported to a required place.
[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.
[0006]
The present invention has been made in view of the above facts, and the main technical problem thereof is that even when the thickness of the semiconductor wafer is significantly reduced by grinding the back surface of the semiconductor wafer, the back surface grinding is performed without damaging the semiconductor wafer. A new and improved semiconductor that can be carried out, can transport the semiconductor wafer as easily as required, and can also freely access the surface of the semiconductor wafer after backside grinding of the wafer It is to provide a wafer processing method.
[0008]
[Means for Solving the Problems]
According to the present invention, as a semiconductor wafer processing method for achieving the main technical problem, a large number of rectangular regions partitioned by streets arranged in a lattice pattern are arranged on the surface, and each of the rectangular regions is arranged. In the method of processing a semiconductor wafer on which a semiconductor circuit is applied,
A plurality of high-rigidity layers are laminated on a low-rigidity layer, and each layer is adhered to each other via an adhesive, and the surface of the semiconductor wafer is adhered to the low-rigidity layer side of the support substrate. A mounting step of mounting the semiconductor wafer on a substrate;
Grinding to reduce the thickness of the semiconductor wafer by adsorbing the surface of the semiconductor wafer onto the chuck means via the support substrate and grinding the back surface of the semiconductor wafer by applying a grinding means to the back surface of the semiconductor wafer Process,
A mounting tape extending across the mounting opening is mounted on a frame having a mounting opening in the center, and the back surface of the semiconductor wafer is adhered to the mounting tape, and the semiconductor is placed in the mounting opening of the frame. A transfer step of mounting a wafer, and then sequentially separating the plurality of high-rigidity layers and the low-rigidity layer of the support base from the surface of the semiconductor wafer for each layer ;
A semiconductor wafer processing method characterized by comprising:
[0009]
The high-rigidity layer is preferably composed of a polyethylene terephthalate sheet or a polyethylene terephthalate film, and the low-rigidity layer is preferably composed of a polyolefin sheet or a polyolefin film. Preferably, the support substrate is larger than the semiconductor wafer, and the periphery of the support substrate extends by 1 to 2 mm beyond the periphery of the semiconductor wafer.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, preferred embodiments of a semiconductor processing method of the present invention and a supporting substrate used therewith will be described in more detail with reference to the accompanying drawings.
[0015]
FIG. 1 shows a typical example of a semiconductor wafer to which the processing method of the present invention can be applied. The illustrated semiconductor wafer 2 has a shape in which a straight edge 4 called an orientation flat is formed on a part of a disk shape, and a large number of rectangular regions 8 are defined on the surface by streets 6 arranged in a lattice pattern. Has been. Each rectangular area 8 is provided with a semiconductor circuit.
[0016]
In the processing method of the present invention, a mounting process is performed. In this mounting process, as shown in FIGS. 2 and 3, the surface of the semiconductor wafer 2 is stuck on the support substrate 10 and the semiconductor wafer 2 is mounted on the support substrate 10. The support substrate 10 may have a disk shape or a shape similar to the semiconductor wafer 2 and a straight edge corresponding to the straight edge 4 of the semiconductor wafer 2.
[0017]
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 housing 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.
[0018]
Supporting substrate 10, which stiffness is constituted by sticking to each other and each layer stacked relatively high rigidity layer multiple synthesis smaller low-rigidity layer via an adhesive, a semiconductor wafer It is important that 2 is attached to the low rigidity layer side. In the illustrated embodiment, the support substrate 10 is composed of a low-rigidity layer 12 positioned at the uppermost position and three high-rigidity layers 14 stacked therebelow. The low rigidity layer 12 may be a polyolefin sheet or a polyolefin film, and the high rigidity layer 14 may be a polyethylene terephthalate sheet or a polyethylene terephthalate film. The pressure-sensitive adhesive is preferably an ultraviolet-curing type that is cured by irradiation with ultraviolet rays and loses or decreases its adhesiveness, or a heat-curable adhesive that is cured by heating and loses or decreases its adhesiveness. It is. An adhesive that is preferably an ultraviolet curable type or a thermosetting type is also applied to the upper surface of the low-rigidity layer 12, and the surface of the semiconductor wafer 2 is adhered to the upper surface of the low-rigidity layer 12 by such an adhesive. The Thus, the semiconductor wafer 2 is mounted on the support substrate 10 with its front surface facing downward, in other words, with its back surface facing upward.
[0019]
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.
[0020]
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.
[0021]
Thus, the following facts should be noted for the support substrate 10 used in the illustrated embodiment. That is, the support substrate 10 is configured by laminating the low-rigidity layer 12 and the high-rigidity layer 14. Therefore, even if the rigidity of the high-rigidity layer 14 is relatively small, the entire laminate has a considerable rigidity. . The low-rigidity layer 12 protects the surface of the semiconductor wafer 2 from external force as a so-called buffer material. Therefore, when the back surface of the semiconductor wafer 2 is ground in the manner shown in FIG. 4, even if the semiconductor wafer 2 is ground to a thickness of 150 μm or less, particularly 50 μm or less, the semiconductor is supported by the support substrate 10. Since the wafer 2 is sufficiently reinforced, the semiconductor wafer 2 can be ground sufficiently satisfactorily without causing damage. On the other hand, when the support substrate 10 is detached from the surface of the semiconductor wafer 2, the three high-rigidity layers 14 are sequentially peeled off instead of simultaneously removing the entire support substrate 10, and then the low-rigidity layer 12 is removed. Can be peeled off. Therefore, when the support substrate 10 is detached from the surface of the semiconductor wafer 2, generation of excessive stress on the semiconductor wafer 2 can be avoided. In addition, when the high-rigidity layer 14 having relatively high rigidity is peeled off, the low-rigidity layer 12 interposed between the high-rigidity layer 14 and the surface of the semiconductor wafer 2 functions as a so-called buffer material. The stress generated in the semiconductor wafer 2 is reduced. In this way, the support substrate 10 can be detached from the surface of the semiconductor wafer 2 without generating excessive stress in the semiconductor wafer 2 and damaging the semiconductor wafer 2. When the entire support substrate 10 having a considerable rigidity is peeled off from the surface of the semiconductor wafer 2 at the same time, there is a possibility that a considerable stress is generated in the semiconductor wafer 2 and the semiconductor wafer 2 is damaged.
[0022]
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.
[0023]
In the illustrated embodiment, the semiconductor wafer 2 is cut along the streets 6 after grinding the back surface of the semiconductor wafer 2 to reduce the thickness of the semiconductor wafer 2 to a predetermined value. Prior to the grinding step shown in FIG. 5, a groove having a required depth can be formed along the street 6 on the surface of the semiconductor wafer 2 (the formation of such a groove is the same as the cutting step described with reference to FIG. 7). Can be accomplished by a similar cutting process). In this case, if the thickness of the semiconductor wafer 2 is reduced by grinding the back surface of the semiconductor wafer 2 in the grinding step shown in FIG. 4, the semiconductor wafer 2 is separated into individual rectangular regions 8 due to the presence of the grooves. The Then, the separated rectangular area 8 is continuously mounted on the support substrate 10. Then, when the transfer process as described with reference to FIG. 5 is performed, a state in which each of the individually separated rectangular regions 8 is attached to the frame 22 via the attachment tape 20 is established. In such a case, as a processing step performed after the transfer step, the individually separated rectangular areas 8 are individually picked up and transported to a required place (for example, on the mounting base on which the rectangular area 8 is to be mounted). What is necessary is just to perform a known pick-up process.
[0024]
【The invention's effect】
According to the semiconductor wafer processing method of the present invention, even when the thickness of the semiconductor wafer is significantly reduced by grinding the back surface of the semiconductor wafer, the back surface grinding can be performed without damaging the semiconductor wafer. It can be transported sufficiently easily as required, and it is also possible to freely access the surface of the semiconductor wafer after backside grinding of the wafer.
[0025]
The semiconductor support substrate of the present invention can be conveniently used as a support substrate for attaching the surface of the semiconductor wafer, and damages the semiconductor wafer when the support substrate is detached from the surface of the semiconductor wafer. It can be avoided reliably.
[Brief description of the drawings]
FIG. 1 is a perspective view showing a typical example of a semiconductor wafer to which a processing method of the present invention is applied .
FIG. 2 is a perspective view showing a state in which a semiconductor wafer is mounted on a support substrate in a mounting step in the processing method of the present invention.
FIG. 3 is a side view showing a state where a semiconductor wafer is mounted on a support substrate in a mounting step in the processing method of the present invention.
FIG. 4 is a simplified side view showing a grinding step in the processing method of the present invention.
FIG. 5 is a simplified cross-sectional view showing a transfer step in the processing method of the present invention.
FIG. 6 is a perspective view showing a state in which the semiconductor wafer is mounted on the frame via the mounting tape after the transfer step in the processing method of the present invention.
FIG. 7 is a simplified cross-sectional view showing a cutting step (processing step) 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 (3)

A large number of rectangular regions partitioned by streets arranged in a lattice pattern are disposed on the surface, and a semiconductor wafer processing method in which a semiconductor circuit is applied to each of the rectangular regions,
A plurality of high-rigidity layers are laminated on a low-rigidity layer, and each layer is adhered to each other via an adhesive, and the surface of the semiconductor wafer is adhered to the low-rigidity layer side of the support substrate. a mounting step of mounting the semiconductor wafer on a substrate,
Grinding said surface of the semiconductor wafer adsorbed on the chuck means through the supporting substrate, allowed to reduce the thickness of the semiconductor wafer to be brought effect the grinding means to the back surface of the semiconductor wafer by grinding the back surface of the semiconductor wafer Process,
A frame having a mounting opening in the center, the semiconductor with mounting a mounting tape extending straddling the said mounting opening, tighten dressing adhered to the back surface of the semiconductor wafer to said mounting tape within said mounting opening of the frame the wafer is mounted, then the sorting process allowed to sequentially separated from the surface of the semiconductor wafer for each layer and the support base plate said plurality of rigid layers of the low stiffness layer,
A method for processing a semiconductor wafer, comprising: The high stiffness layer is composed of polyethylene terephthalate sheet or a polyethylene terephthalate film, the low stiffness layer is composed of a polyolefin sheet or polyolefin film, method for processing a semiconductor wafer according to claim 1, wherein.   3. The method of processing a semiconductor wafer according to claim 1, wherein the support substrate is larger than the semiconductor wafer, and the periphery of the support substrate extends by 1 to 2 mm beyond the periphery of the semiconductor wafer.

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