JP2008041748A - Fixture for semiconductor wafer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fixture for a semiconductor wafer capable of eliminating the possibility of the slipping-off of a dicing tape from a frame, and the breaking and cracking of the flaked semiconductor wafer and a chip, regardless of the quality of the material, or the like of the dicing tape and the presence of the irradiation of ultraviolet rays. <P>SOLUTION: The fixture for the semiconductor wafer has the hollow frame 1 housing the semiconductor wafer W flaked by a back grinding and the dicing tape 10, detachably holding and loading the thin semiconductor wafer W housed in the frame 1. A sticking layer 20, stuck to the dicing tape 10, is laminated on the rear of the frame 1. Since the slipping-off is prevented by firmly sticking the sticking layer 20 of the frame 1 to the dicing tape 10; the risk of the slip-off of the dicing tape 10 from the frame 1 and the breaking and cracking of the thin light semiconductor wafer W is eliminated, even if the quality of the material of a base layer is changed into an EVA having a small elongation at tension, and the dicing tape 10 having a low adhesion is adopted. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a fixing jig for a semiconductor wafer used in a dicing process or a die bonding process of a semiconductor wafer.

  Conventionally, when a semiconductor package is assembled by processing a semiconductor wafer having a thickness of about 100 μm by back grinding, first, a thin semiconductor wafer is mounted on a dicing tape called a UV tape of a dicing frame (not shown). The dicing tape is diced, and the back side of the dicing tape is irradiated with UV light to weaken the adhesive strength. The dicing frame is set in an expander called an expansion device, and then the dicing tape of the dicing frame is stretched evenly in all directions (expanded). The chips separated individually are picked up so as not to come into contact with surrounding chips, and a semiconductor package is assembled (see Patent Documents 1 and 2).

  The dicing frame is formed in a ring shape using stainless steel or the like, and a hollow frame that accommodates a thin semiconductor wafer and a flexible that mounts the thin semiconductor wafer that is directly adhered to the back surface of the frame so as to be peeled off. And dicing tape. The dicing tape has a base material layer formed to have a thickness of about 50 to 200 μm by extrusion using a soft soft vinyl chloride resin, and an acrylic adhesive is applied to the base material layer. It is formed in the multilayer structure provided with the adhesive layer formed in thickness of -50micrometer or more.

  By the way, in recent years, further thinning of the semiconductor wafer is required, and a material change is required for the dicing tape of the dicing frame. In view of this point, semiconductor wafers are required to be further thinned (for example, about 50 μm thick) in view of recent downsizing and thinning of portable devices. If the semiconductor wafer is further thinned to satisfy this requirement, the semiconductor wafer and the diced chips are very likely to be chipped and broken easily. Therefore, when handling, it is necessary to apply as little external force as possible.

In addition, the soft vinyl chloride resin that forms the base layer of the dicing tape is given flexibility by the addition of a plasticizer, but the plasticizer moves to the adhesive layer and swells it to pick up the chip. The adhesive layer swollen on the chip may move, or when the dicing tape is peeled off from the frame of the dicing frame, a part of the adhesive layer may remain on the frame and deteriorate the productivity and quality. Therefore, in recent years, there is an increasing demand for changing the material of the base material layer from a soft vinyl chloride resin to a polyolefin resin such as EVA (ethylene vinyl acetate).
JP 2006-73963 A JP 2006-49509 A

  However, if the material of the base material layer is simply changed to EVA, there will be a new major problem that the dicing tape is displaced from the frame of the dicing frame, and a thin semiconductor wafer or chip is chipped or broken.

  In other words, if the material of the base material layer is changed to EVA, it is possible to improve productivity and quality by preventing the migration and remaining of the pressure-sensitive adhesive layer, but the elongation at the time of pulling becomes small. In the case of sufficient separation, it is necessary to stretch by applying a larger force than in the case of a soft vinyl chloride resin. Based on this, when the dicing tape is stretched by applying a large force, there arises a problem that the dicing tape is displaced from the frame and detached, or a thin semiconductor wafer or chip is chipped or broken.

As means for solving such problems, (1) a method of further reducing the adhesive strength of the dicing tape and extremely reducing the adhesive strength at the time of chip pickup, and (2) increasing the initial adhesive strength of the dicing tape. In addition, there has been proposed a method of reducing the adhesive strength by irradiating ultraviolet rays from the dicing tape surface side after the dicing operation is completed.
However, when the method (1) is adopted, chipping (called chipping) on the back side during dicing occurs frequently, and the adhesive strength of the dicing tape is low, so when the dicing tape is stretched in all directions. There arises a new problem that the dicing tape is peeled off.

  Further, when the method (2) is adopted, it is necessary to further strongly reduce the adhesive strength after ultraviolet irradiation as the semiconductor wafer is further thinned. In addition, if the adhesive strength is reduced by irradiating the entire semiconductor wafer including the dicing frame from the dicing tape surface side in consideration of productivity, the adhesive strength between the frame and the dicing tape is reduced, and the dicing tape is completely removed. When extending in the direction, there is a high possibility of causing peeling of the dicing tape.

  In order to avoid such harmful effects, the frame may be irradiated with ultraviolet rays by masking the frame to prevent ultraviolet rays. However, in this case, the productivity will be significantly reduced, and the adhesive will become more sensitive to ultraviolet rays, resulting in fluorescence. It is easily affected by lights and sunlight, and complicated management is required for movement and storage between factories and processes.

  The present invention has been made in view of the above, and there is a risk that the dicing tape may be detached from the frame and the sliced semiconductor wafer or chip may be chipped or cracked regardless of the material of the dicing tape or the presence or absence of ultraviolet irradiation. It aims at providing the fixing jig for semiconductor wafers which can be excluded.

In the present invention, in order to solve the above-mentioned problem, a hollow frame for accommodating a thinned semiconductor wafer and a dicing tape for mounting the semiconductor wafer accommodated in the frame are provided,
An adhesive layer that adheres to the dicing tape is provided on the back surface of the frame.

In addition, a mold release process can be performed on the surface of the frame.
Further, a fitting groove for the adhesive layer can be formed on the back surface of the frame.
In addition, the fitting groove can be formed deeper than the thickness of the adhesive layer on the back surface of the frame.

Furthermore, a hollow frame that accommodates the thinned semiconductor wafer and a dicing tape that mounts the semiconductor wafer accommodated in the frame are set in an expansion device after the semiconductor wafer is diced, and the dicing tape is stretched, It widens the interval between multiple chips separated by dicing,
An adhesive layer that adheres to the dicing tape may be provided on the back surface of the frame.

  Here, the thinned semiconductor wafer, frame, and dicing tape in the claims may or may not be integrated by a wafer mounter or the like. The semiconductor wafer is not particularly limited to a 200 mm type, a 300 mm type, a 450 mm type, a recycled wafer or the like. The dicing tape may be a tape containing a soft vinyl chloride resin or a tape containing a polyolefin resin.

  The dicing tape may or may not be a type that adheres when irradiated with ultraviolet rays or has a reduced adhesive strength. Furthermore, the fixing jig for a semiconductor wafer according to the present invention can be used in a dicing process in which the semiconductor wafer is cut into individual chips and separated, and the separated chips are picked up and mounted on a lead frame and bonded. It can also be used in a die bonding process or the like.

  According to the present invention, the adhesive layer of the frame strongly adheres to the dicing tape and increases the degree of adhesion. Deviation and dropout can be regulated.

  According to the present invention, regardless of the material of the dicing tape or the presence or absence of ultraviolet irradiation, it is possible to effectively eliminate the possibility that the dicing tape is displaced from the frame and detached, or the sliced semiconductor wafer or chip is chipped or cracked. There is an effect that can be.

Further, if a fitting groove for the adhesive layer is formed on the back surface of the frame and the adhesive layer is adhered to the fitting groove, proper positioning of the adhesive layer is facilitated.
Furthermore, if the fitting groove is formed deeper than the thickness of the adhesive layer on the back surface of the frame, the adhesive layer will not protrude from the back surface of the frame, so even if multiple frames are stacked up and down, they are positioned below. It can suppress that the adhesion component of the adhesion layer of a flame | frame transfers to an upper flame | frame, and frames adhere | attach.

  Hereinafter, a preferred embodiment of the present invention will be described with reference to the drawings. A fixing jig for a semiconductor wafer in this embodiment accommodates a thinned semiconductor wafer W as shown in FIGS. And a flexible dicing tape 10 that detachably holds and mounts a thin semiconductor wafer W accommodated in the frame 1, and an adhesive layer that adheres to the dicing tape 10 on the back surface of the frame 1. 20 are stacked and used in a dicing process or a die bonding process of the semiconductor wafer W.

  The semiconductor wafer W has a diameter of, for example, 300 mm (12 inches), and the back surface is back-ground by a back grinder so that it is ground and formed to a thickness of about 775 μm to a thickness of about 50 μm. The circuit surface which is the surface is exposed by being adhesively held on the top.

  As shown in FIG. 1 and FIG. 2, the frame 1 is formed in a substantially flat ring-shaped flat plate larger than the semiconductor wafer W thinned using, for example, stainless steel, PPS resin, or the like, and at least the periphery of the hollow portion on the surface Is subjected to mold release processing such as uneven texturing 2 and functions to accommodate the semiconductor wafer W in the hollow portion with a gap. The size and dimensions of the frame 1 are set based on the SEMI standard so that it can be stored in a semiconductor wafer storage container (FOSB, FOUP, etc.) (not shown).

  As shown in FIGS. 1 and 2, the dicing tape 10 includes a base material layer formed to a thickness of about 50 to 200 μm by, for example, extrusion using EVA, and an acrylic adhesive on the surface of the base material layer. By applying the agent, it is formed to a thickness of about 10 to 50 μm or more, is formed into a multilayer structure including the back surface of the semiconductor wafer W and an adhesive layer that adheres, and is cut into a planar circle.

  In such a dicing tape 10, after the semiconductor wafer W is diced in the dicing process, a fixing jig is set in an expander (expansion device) (not shown) or an expand part (expansion device) of the die bonder in the die bonding process. Then, it functions to make it easy to pick up each chip by expanding (expanding) evenly by the apparatus and widening the interval between a plurality of chips separated by dicing.

  As shown in FIG. 2, the pressure-sensitive adhesive layer 20 is formed in a substantially ring shape by applying, drying, or adhering an acrylic pressure-sensitive adhesive, a polypropylene-based elastomer, a gel sheet or the like to the periphery of the hollow portion on the back surface of the frame 1. The thin film is formed in a thin layer and functions to adhere to the pressure-sensitive adhesive layer of the dicing tape 10 in surface contact. Other parts are the same as in the conventional example.

  In the above, in order to assemble the semiconductor package by processing the semiconductor wafer W diced by a dicing device (not shown), the dicing tape 10 of the fixing jig is set on the expander device, and the frame 1 of the fixing jig is pushed down. If the dicing tape 10 is stretched evenly in all directions (expanded) and the individually separated chips are picked up so as not to come into contact with surrounding chips, the semiconductor package can be assembled.

  When the dicing tape 10 is stretched or chips are picked up, the dicing tape 10 is lifted by pins from the back side to pick up the chips, or the dicing tape 10 on which the chips are mounted is gradually peeled off from the end. Thus, a pinless pickup system that picks up the chip is appropriately employed.

  According to the above configuration, the dicing tape 10 is not simply adhered to the frame 1 only by the adhesive layer, but the adhesive layer 20 of the frame 1 is firmly adhered to the dicing tape 10 to prevent displacement and dropping. Even if the material of the base material layer is changed to EVA having a small elongation at the time of pulling, or the dicing tape 10 having a low adhesive strength is adopted, the dicing tape 10 stretched from the frame 1 in the die bonding process may be displaced and removed. There is no risk that the thin and light semiconductor wafer W or chip will be chipped or broken. In addition, this effect can greatly contribute to the production of semiconductors that require further thinning in the future, such as system-in-package and large-capacity memory.

  Further, since it is not necessary to irradiate the entire semiconductor wafer W including the dicing frame 1 with ultraviolet rays from the dicing tape surface side to reduce the adhesive force, in addition to maintaining and improving productivity, avoid complicated management of ultraviolet rays. In addition, it is possible to facilitate the transfer and storage between factories and processes. Furthermore, since the surface of the frame 1 is subjected to a mold release process, even when the plurality of frames 1 from which the dicing tape 10 has been peeled are stacked and managed in a plurality of stages or stocked, the adhesive layer 20 of the frame 1 located below is stored. It becomes possible to reduce that the adhesive component of this transfers to the surface of the flame | frame 1, and the flame | frame 1 adheres.

  Next, FIG. 3 shows a second embodiment of the present invention. In this case, the fitting groove 3 for the adhesive layer 20 is cut into a substantially ring shape on the periphery of the hollow portion on the back surface of the frame 1. The depth of the adhesive layer 20 is slightly longer than the thickness of the pressure-sensitive adhesive layer 20, and the flat substantially ring-shaped pressure-sensitive adhesive layer 20 is adhered to the fitting groove 3 so as to be immersed therein. The other parts are the same as those in the above embodiment, and the description thereof is omitted.

  Also in this embodiment, the same effect as the above embodiment can be expected, and the adhesive layer 20 is adhered to the fitting groove 3 recessed from the back surface, not the back surface of the frame 1. Clearly it will be easier. Moreover, since the depth of the fitting groove 3 is deeper than the thickness of the adhesive layer 20 and the adhesive layer 20 does not protrude from the back surface of the frame 1, even when a plurality of frames 1 are stacked and stocked in multiple stages. It is clear that the adhesive component of the adhesive layer 20 of the frame 1 positioned below can be reliably prevented with a simple configuration that the adhesive component 20 moves to the surface of the frame 1 and adheres to each other.

  Next, FIG. 4 shows a third embodiment of the present invention. In this case, a planar substantially ring-shaped fitting groove 3 is cut out in a U-shaped cross section at the periphery of the hollow portion on the back surface of the frame 1. The depth of the adhesive layer 20 is slightly deeper than the thickness of the adhesive layer 20, and the adhesive layer 20 is adhered and immersed in the fitting groove 3. The other parts are the same as those in the above embodiment, and the description thereof is omitted.

  Also in this embodiment, the same effect as the above embodiment can be expected, and unlike the second embodiment, the adhesive layer 20 is formed on the inner peripheral wall defining the hollow portion of the frame 1 from the inside of the fitting groove 3. Obviously, there is no fear of the end portion protruding, and further, the shape of the fitting groove 3 can be diversified.

  In the above embodiment, the frame 1 is simply shown, but an RF tag of the RFID system may be attached to the surface of the frame 1 for convenience of management. Moreover, in the said embodiment, although the adhesion layer 20 was surface-contacted to the dicing tape 10, it is not limited to this at all. As long as the dicing tape 10 extended from the frame 1 can be prevented from shifting and coming off, or the thin semiconductor wafer W or chip can be chipped or cracked, it can be adhered by point contact or line contact.

  Moreover, although the adhesion layer 20 was adhered to at least the periphery of the hollow part on the back surface of the frame 1, it is not limited to this. For example, the adhesive layer 20 may be adhered to at least the periphery of the hollow portion on the back surface of the frame 1 via a double-sided adhesive tape. Further, a plurality of adhesive layers 20 having an arc shape may be arranged on the back surface of the frame 1 at intervals and adhered.

Hereinafter, examples of a fixing jig for a semiconductor wafer according to the present invention will be described together with comparative examples.
Example 1
First, an acrylic adhesive (manufactured by Soken Chemical Co., Ltd.) melted at a width of 15 mm radially outward from the periphery of the hollow portion in the circumferential direction of the back surface of a stainless steel frame (manufactured by DISCO Co., Ltd.) formed into a substantially ring shape ) Was applied to a thickness of about 50 μm, and the acrylic adhesive was dried with hot air to form a dried adhesive layer having a thickness of about 20 μm. The frame was formed to have an inner diameter of 350 mm and an outer diameter of 400 mm so as to accommodate a 300 mm diameter semiconductor wafer.

  Once the adhesive layer is formed, a UV-type dicing tape (product name D650 manufactured by Lintec Corporation) is adhered to the adhesive layer with a wafer mounter (product name RAD2700F12 manufactured by Lintec Corporation), and ultraviolet rays are applied to the whole from the back side. After irradiating with a UV irradiation device (trade name RAD2000F12, manufactured by Lintec Co., Ltd.), the expanded portion of the die bonder device (trade name: SPA-300, manufactured by Shinkawa Co., Ltd.) is expanded with a drop of 10 mm, 20 mm, or 30 mm. The presence or absence of omission was observed.

  As a result of the expansion, the dicing tape did not come off from the frame, and good bonding processing could be performed.

Example 2
First, using a PPS resin (trade name FZ2140, manufactured by Dainippon Ink Co., Ltd.) and a known injection molding machine, a plane substantially ring-shaped frame is injection molded to a thickness of 3.5 mm. Compliant.

  Also, a polypropylene elastomer (trade name Tafflen 3712 manufactured by Sumitomo Chemical Co., Ltd.) is extruded by a known T-die melt extrusion method to form a film having a thickness of 50 μm, and this film is formed into a ring shape having an inner diameter of 350 mm and an outer diameter of 380 mm. The adhesive layer was formed by cutting, and this adhesive layer was adhered to the frame in the circumferential direction on the back surface via a double-sided adhesive tape (trade name Nystack, manufactured by Nichiban Co., Ltd.).

  Next, the same dicing tape as that in Example 1 was adhered to the adhered adhesive layer, and ultraviolet rays were irradiated on the whole from the back side by a UV irradiation device (trade name RAD2000F12 manufactured by Lintec Corporation), and then a die bonder device (stock) The product was expanded by dropping 10 mm, 20 mm, and 30 mm in the expanded portion of Shinkawa Co., Ltd. (trade name SPA-300), and the presence or absence of dicing tape displacement or dropout was observed.

  As a result of the expansion, the dicing tape did not come off from the frame, and good bonding processing could be performed.

Example 3
First, a 0.5-mm-thick urethane-based gel sheet (trade name Hypergel manufactured by Exeal Corporation) was cut into a ring shape having an inner diameter of 350 mm and an outer diameter of 380 mm to form an adhesive layer. It adhered to the back surface circumferential direction of the frame via a double-sided adhesive tape (trade name Nystack, manufactured by Nichiban Co., Ltd.).

  Next, the same dicing tape as that in Example 1 was adhered to the adhered adhesive layer, and ultraviolet rays were irradiated on the whole from the back side by a UV irradiation device (trade name RAD2000F12 manufactured by Lintec Corporation), and then a die bonder device (stock) The product was expanded by dropping 10 mm, 20 mm, and 30 mm in the expanded portion of Shinkawa Co., Ltd. (trade name SPA-300), and the presence or absence of dicing tape displacement or dropout was observed.

  As a result of the expansion, the dicing tape did not peel off from the frame, and the bonding process could be performed satisfactorily.

Example 4
First, a fitting groove for the adhesive layer is cut out into a flat ring shape at the periphery of the hollow portion on the back surface of the frame used in Example 2 so that the depth is slightly 0.1 mm deeper than the thickness of the adhesive layer. Then, a flat ring-shaped adhesive layer was formed in the fitting groove. For the adhesive layer, an acrylic adhesive (manufactured by Soken Chemical Co., Ltd.) melted in the fitting groove is applied to a thickness of about 50 μm, and this acrylic adhesive is dried with hot air to form a layer having a thickness of about 20 μm. It was formed by laminating. Others were observed in the same manner as in the above example for the presence or absence of dicing tape displacement or dropout.

  As a result of the expansion, the dicing tape did not peel off from the frame, and the bonding process could be performed satisfactorily. Moreover, although the several flame | frame was laminated | stacked on the upper and lower multistage, it was able to prevent that the adhesion component of the adhesion layer of the flame | frame located below transfers to the surface of a flame | frame, and frames adhere.

Comparative Example The same dicing tape as that of Example 1 was directly adhered to the periphery of the hollow part on the back surface of the frame used in Example 2, and UV rays were irradiated on the entire surface from the back side with a UV irradiation device (trade name, manufactured by Lintec Corporation). RAD2000F12), and then expanded by dropping 10 mm, 20 mm, and 30 mm at the expanding portion of the die bonder apparatus (trade name SPA-300, manufactured by Shinkawa Co., Ltd.), and the presence or absence of dicing tape displacement or dropout was observed.

  As a result of the expansion, the dicing tape partially peeled off from the frame, resulting in pickup displacement and equipment stop during bonding, resulting in hindrance to bonding processing.

It is a perspective explanatory view showing typically an embodiment of a fixture for semiconductor wafer concerning the present invention. It is a fragmentary sectional view showing typically the upside down fixing jig in the embodiment of the fixing jig for semiconductor wafer concerning the present invention. It is a fragmentary sectional view showing typically the upside down fixing jig in the 2nd embodiment of the fixing jig for semiconductor wafers concerning the present invention. It is a partial cross section explanatory view showing typically the fixing jig turned upside down in the 3rd embodiment of the fixing jig for semiconductor wafers concerning the present invention.

Explanation of symbols

1 Frame 2 Wrinkle processing (release process)
3 Fitting groove 10 Dicing tape 20 Adhesive layer W Semiconductor wafer

Claims (4)

A fixing jig for a semiconductor wafer comprising a hollow frame for accommodating a semiconductor wafer that has been cut into a thin piece, and a dicing tape for mounting the semiconductor wafer accommodated in the frame,
A fixing jig for a semiconductor wafer, characterized in that an adhesive layer that adheres to a dicing tape is provided on the back surface of the frame.   The fixing jig for a semiconductor wafer according to claim 1, wherein a release treatment is performed on a surface of the frame.   The fixing jig for a semiconductor wafer according to claim 1 or 2, wherein a fitting groove for an adhesive layer is formed on the back surface of the frame.   The fixing jig for a semiconductor wafer according to claim 3, wherein the fitting groove is formed deeper than the thickness of the adhesive layer on the back surface of the frame.

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