JP2007027474A - Base material film for wafer full-cut dicing tape, and wafer full-cut dicing tape using the film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a base material film for a wafer full-cut dicing tape, capable of suppressing scraps in wafer full-cut dicing. <P>SOLUTION: The base material film for the wafer full-cut dicing tape is composed of an ethylene system copolymers of at least a first class, which is selected between ethylene-ethyl acrylate copolymer and ethylene vinylacetate copolymer, within a range of melting point ≥83°C and ≤88°C, as measured by a DSC method, based on JIS K 7121. The surface roughness (Ra) of the base material film is preferably 0.5-1.6 μm for the wafer full-cut dicing tape. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention mainly relates to a base film for a wafer full cut dicing tape for dicing a silicon wafer in a process of manufacturing various semiconductors, and a wafer full cut dicing tape having the same.

  Conventionally, as a base film of a wafer full-cut dicing tape, an inexpensive and versatile ethylene-ethyl acrylate copolymer (hereinafter referred to as “EEA”), an ethylene-vinyl acetate copolymer (hereinafter referred to as “ Synthetic resins such as "EVA") have been used (see Patent Document 1).

However, a wafer full cut dicing using a base film having a single resin single layer structure made of a synthetic resin such as conventional EEA and EVA, that is, a dicing blade is referred to as a work material (hereinafter referred to as “workpiece”). In the wafer full-cut dicing in which the blade tip reaches the base film located under the workpiece, thread-like cutting waste (hereinafter referred to as “cutting waste”) is generated. There was a problem. And generation | occurrence | production of such cutting waste was still a problem which became apparent with the miniaturization of the chip | tip obtained by cutting of a workpiece | work, and diversification of a dicing blade.
JP 2001-354930 A Narusawa, “Mechanical properties of plastics”, Sigma Publishing (1994) 220-221 pages

  The present invention aims to solve this problem.

  That is, an object of the present invention is to provide a base film of a wafer full cut dicing tape that suppresses generation of cutting waste in wafer full cut dicing and a wafer full cut dicing tape having the same.

  In the full-cut dicing of a dicing tape having a base film composed of a synthetic resin, the present inventors have made extensive studies to solve the above-mentioned problem of generation of cutting waste. [At least one selected from ethylene-ethyl acrylate copolymers and ethylene-vinyl acetate copolymers having a melting point of 83 ° C. or higher and 88 ° C. or lower as measured by DSC method according to JIS K 7121] It was found that only the base film of a wafer full-cut dicing tape composed of an ethylene-based copolymer ”can suppress the generation of cutting scraps, and the present invention has been completed.

  In order to achieve the above object, the invention described in claim 1 is an ethylene-ethyl acrylate copolymer having a melting point measured by a DSC method in accordance with JIS K 7121 in the range of 83 ° C to 88 ° C. A substrate film for a wafer full-cut dicing tape, characterized by comprising at least one ethylene copolymer selected from ethylene-vinyl acetate copolymers.

  The invention described in claim 2 is the invention described in claim 1, wherein the surface roughness (Ra) of the base film of the wafer full-cut dicing tape is 0.5 to 1.6 μm. It is characterized by.

  The invention described in claim 3 is a wafer full cut characterized in that an adhesive layer is provided on at least one surface of the base film of the wafer full cut dicing tape according to claim 1 or 2. Dicing tape for use.

  The present invention has the following effects.

  According to the invention described in claim 1, an ethylene-ethyl acrylate copolymer and an ethylene-vinyl acetate copolymer having a melting point measured by DSC method according to JIS K 7121 in the range of 83 ° C. to 88 ° C. Since it is comprised with the at least 1 sort (s) of ethylene-type copolymer chosen from coalescence, the base film of the wafer full cut dicing tape which suppressed generation | occurrence | production of the cutting waste in wafer full cut dicing can be provided.

  According to the invention described in claim 2, since the surface roughness (Ra) of the base film of the dicing tape is 0.5 to 1.6 μm, it is possible to prevent blocking and hugging to the roll. it can.

  According to the invention described in claim 3, since the adhesive layer is provided on at least one surface of the base film of the wafer full-cut dicing tape according to claim 1 or 2, the wafer full-cut dicing is provided. It is possible to provide a base film for a wafer full cut dicing tape in which generation of cutting waste is suppressed.

  The present inventors regard the dicing process as a process in which cutting / grinding processing of a polymer material is applied, and follow the tribology, that is, wear science, between the blade and the base film during dicing. It was thought that the natural phenomenon occurred and the generation of cutting waste basically followed. And since the tribology of the resin is a combination of complicated factors, it is difficult to easily specify the cause of the generation of cutting waste. For example, Non-Patent Document 1 includes various resin tribology phenomena. Of these, it was recognized that the effects of ablation and the melting phenomenon seem to be related to the generation of chips. In the former, the solid physical property of the resin becomes a problem, and in the latter, the melt physical property of the resin becomes a problem.

  Further, Non-Patent Document 1 describes that when the friction speed increases at a certain face-to-face pressure, the surface of the plastic melts due to heat. In dicing, the base film normally melts because the blade rotates at a high speed of 20000-45000 rpm, and the base film melt is stretched by relative displacement (feed) between the blade and the work piece. It is thought that cutting waste is generated. Therefore, the present inventors considered that it is necessary to pay attention to the melt physical properties in order to suppress the cutting waste derived from the base film.

  In addition, the present inventors have found that the correlation between the cutting temperature of dicing and the base film resin melting point is extremely important for the suppression of cutting waste. Specifically, if the base film resin melting point is sufficiently lower than the cutting temperature, the surface of the base resin melts smoothly by the rotation of the blade during dicing and the grinding resistance is reduced, resulting in suppression of cutting waste. I found out.

  However, there has never been a known document disclosed with a clear measurement method for the temperature reached by the resin during dicing. Therefore, the present inventors conducted the following experiment. That is, for various olefin-based resin films, first, after clarifying the respective melting points by the DSC method (JIS K 7121), after selecting films having different melting points and putting one cutting line in one direction by dicing Then, dicing was performed at a fine interval in a direction perpendicular to the cutting line, and the dicing line was observed with a microscope. As a result, in the material having a melting point of around 90 ° C., the locus position of the first dicing was greatly displaced by the right-angled line inserted later, and there was particularly remarkable plastic deformation. According to Non-Patent Document 1, such a large deformation involves melting of the resin. On the other hand, such a displacement was not recognized in the material having a melting point of about 110 ° C.

  From the above experimental results, the present inventors have found that the cutting temperature is in the range of 90 ° C to 110 ° C. In actual dicing, that is, in a state where the workpiece is attached, the cutting resistance further increases, and thus the substrate temperature rises. Therefore, in the present invention, the ethylene copolymer having a melting point of about 90 ° C., which is considered to surely melt, was diced under various dicing conditions, and the generation state of cutting waste was examined. Hereinafter, the melting point of the base film material resin described in the present invention was measured by the DSC method (JIS K 7121). Moreover, the base film used for evaluation was obtained by T-die molding. The thickness was about 150 μm. In selecting a material, MFR 15 or less was used in consideration of the strength of the film.

  Generation | occurrence | production of the cutting waste was evaluated by observing the cutting line obtained by dicing with a microscope. Dicing was performed on a workpiece in which an acrylate adhesive material was applied to one surface of a base film to form a tape, and a silicon wafer was adhered to the adhesive surface. The rotation speed of the blade was 40000 rpm, and the feed rate was in the range of 40 mm / s to 160 mm / s. The dicing interval was every 10 mm. For dicing, a blade having a blade width of 35 μm for wafer dicing was used.

  As a result, in the case of a material having a melting point of less than 83 ° C., it was recognized that the film was fused to the vacuum chuck table of the dicing apparatus. In the material having a melting point exceeding 88 ° C., cutting waste was not suppressed. Furthermore, the effects of the present invention were exhibited when EEA and EVA having a melting point of 83 ° C. or higher and 88 ° C. or lower were used. In the ethylene-methyl methacrylate copolymer (EMMA) and ethylene-methacrylic acid (EMAA) in the same melting point range, generation of cutting scraps was sometimes observed.

  That is, according to the above experiment, it is suggested that cutting waste can be suppressed by setting the melting point to a certain value or less regardless of the type of monomer copolymerized with polyethylene. Especially, the effect was recognized notably in EEA and EVA.

  Therefore, the base film of the wafer full-cut dicing tape of the present invention includes an ethylene-ethyl acrylate copolymer and an ethylene having a melting point measured by DSC method in accordance with JIS K 7121 in the range of 83 ° C. to 88 ° C. -It comprises at least one ethylene copolymer selected from vinyl acetate copolymers. Thus, at least one selected from ethylene-ethyl acrylate copolymer and ethylene-vinyl acetate copolymer having a melting point measured by DSC method according to JIS K 7121 in the range of 83 ° C. or higher and 88 ° C. or lower. When comprised with an ethylene-based copolymer, it is possible to provide a substrate film for a wafer full-cut dicing tape in which generation of cutting waste is suppressed in wafer full-cut dicing.

  According to the present invention, it has been found that when the base film of the wafer full-cut dicing tape is sufficiently melted, cutting burrs are reduced, and as a result, cutting waste is significantly suppressed. Furthermore, it has been found that when the blade feed rate is slow and an arbitrary portion of the substrate is cut by the blade for a long time, cutting waste is likely to be generated.

  Therefore, in the present invention, the effect is particularly apparent when the feed rate is 60 mm / s or more, and cutting waste may be generated at 40 mm / s. Moreover, when it exceeds 120 mm / s, in the base film of this invention, it will become easy to generate | occur | produce chipping of a workpiece | work, and its practicality is scarce. From the above, the base film of the present invention is most effective when the dicing feed rate is 60 mm / s or more and 120 mm / s or less.

  The preferable thickness of the base film of the present invention is 70 to 300 μm. When the thickness of the substrate film is less than 70 μm, there is a concern of the substrate fusion due to the cutting heat of dicing. Further, when the thickness of the substrate film exceeds 300 μm, the weight increases, so it is not practical in terms of both cost and workability, and expandability deteriorates, making it difficult to pick up diced wafer chips. Become.

  Moreover, in this invention, in order to suppress blocking, it is preferable that the unevenness | corrugation is formed in the single side | surface of a base film at least by embossing or embossing. The surface roughness of the base film of the present invention is preferably 0.5 to 1.6 μm in arithmetic mean Ra, and more preferably 0.7 to 1.0 μm. If the surface roughness of the substrate film of the present invention is less than 0.5 μm, blocking may occur, and if it exceeds 1.0, the visibility is impaired.

  Supplementing the concavo-convex processing, in particular, when a base film is produced using a resin material whose physical properties are defined in the present invention, blocking and winding around the roll are likely to occur. Therefore, it is necessary to add an anti-blocking material, a slip material, etc., and / or uneven processing. The additive is preferably less than 2 parts by weight with respect to 100 parts by weight of the resin. When the addition amount increases, the additive may bleed on the surface of the base film, and peeling may occur at the interface between the pressure-sensitive adhesive layer and the base film layer. When such a tape is used, since the adhesive property of the tape is lowered, the work pieces are scattered during dicing. Therefore, the base film of the wafer full-cut dicing tape of the present invention can be subjected to anti-blocking treatment by concavo-convex processing rather than addition of an additive, and has a higher degree of completion.

  The substrate film of the wafer full-cut dicing tape of the present invention is sufficiently effective with a single material and a single layer structure, but one kind or two or more kinds of resins satisfying the physical properties defined in the present invention are mixed. It is possible to use mixed materials which mainly contain In the case where the blade cuts only a layer mainly containing a resin that satisfies the physical properties defined in the present invention, it is also possible to use a film having a laminated structure in which an arbitrary resin is provided in a layer where the blade is not cut. The effect is unimpeded. However, the structure of the mixed material or the laminated film is not preferable because it not only increases the cost but also has poor recyclability and high environmental load. Therefore, the implementation of the present invention most preferably illustrates the configuration of a single resin material and a single layer.

  The base film of the wafer full-cut dicing tape of the present invention may be subjected to a surface treatment such as corona discharge on at least one side of the base film before the adhesive layer is applied to the base film. These surface treatments such as corona discharge can improve the adhesiveness between the pressure-sensitive adhesive and the base film, and further increase the practicality in carrying out the present invention. Moreover, you may irradiate energy rays, such as an electron beam, to this base film before application | coating of the adhesive layer to the base film of this invention. By this step, it is possible to impart properties such as improving the substrate strength of the film.

  The dicing tape of this invention is provided with an adhesive layer on at least one surface of the base film of the dicing tape according to any one of claims 1 to 3. Thus, when the pressure-sensitive adhesive layer is provided on at least one surface of the base film of the dicing tape according to any one of claims 1 to 3, generation of cutting waste is suppressed in full-cut dicing. A dicing tape can be provided.

(Production of film)
The base films in Examples 1 to 3 and Comparative Examples 1 to 14 were prepared by extruding the resins shown in Table 1 below using a T die. Mitsui DP in Table 1 is Mitsui DuPont Chemical Company. The width of the die was 550 mm, and the opening of the extruded portion (lip) was 500 μm. The width | variety of the collection | collection film cut | judged both ends by providing a cutter in the winding-up process, and was finally set to 300 mm. The target thickness was 150 μm, and a film with a total length of 50 m was obtained as a specimen while adjusting with the winding speed.

  The thickness of the specimen is determined by cutting out a card-sized specimen at both ends and the center of the film at the 5th, 15th, and 30m sections from the beginning of winding, and measuring each thickness with a dial gauge. went. For the target thickness of 150 μm, all the parts in the range of ± 10 μm are subjected to surface corona treatment, or after electron beam irradiation, a 15 μm thick acrylic adhesive layer is provided on one side by coating, for evaluation Dicing tape was obtained.

(Dicing test)
As the dicing apparatus, DAD341 manufactured by DISCO was used. The blade used was NBC-ZH2050-27HEEE made by DISCO. The blade width of this blade is 35 μm. The rotation speed of the blade was 40,000 rpm, and the feed rate was 40, 60, 80, 100, 120 mm / s. The water temperature of the cooling water was 25 ° C., and the amount of water was 1.0 L / min.

  As a dicing workpiece, a wafer piece having a thickness of 600 μm previously cut into 40 mm × 40 mm was used. After the work was adhered to the dicing tape, the dicing tape was placed on the chuck table of the dicing apparatus. The dicing pattern was diced (second direction) with a similar pattern so that it was 90 ° with the first direction after dicing at 10 mm intervals (first direction). About the dicing depth, it cut | disconnected to 40 micrometers from the adhesive material side of the base film.

  The presence / absence of generation of cutting scraps after dicing was observed using an ultra-depth morphological observation microscope (VK-8500 manufactured by Keyence Corporation) at a magnification of 1000 to 2500 times. The observation targets were all dicing lines formed on the wafer. The number of tests was 10 times for one type of film, and the number of tests was taken when even one beard-like cutting waste was found on the workpiece. However, this observation was performed only for a film that had never been fused by dicing. The test results are shown in Table 2 below.

In Table 2, the criteria for determination of fusion properties are
○: The tape can be pulled away from the chuck table of the dicing machine after dicing, and there is no problem in practical use. It is assumed that there is a problem, and the criterion for wafer dicing is
○: There is no generation of cutting waste and there is no problem in practical use. ×: There is generation of cutting waste, and there is a problem in practical use.
○: No fusing or generation of cutting waste and no problem in practical use ×: Fusing or generation of cutting waste is present, and there is a practical problem.

Claims (3)

  At least one ethylene copolymer selected from ethylene-ethyl acrylate copolymer and ethylene-vinyl acetate copolymer having a melting point measured by DSC method in accordance with JIS K 7121 in the range of 83 ° C. to 88 ° C. A base film for a wafer full-cut dicing tape, characterized by comprising a united body.   The base film of the wafer full cut dicing tape according to claim 1, wherein the surface roughness (Ra) of the base film of the wafer full cut dicing tape is 0.5 to 1.6 µm. .   3. A wafer full-cut dicing tape, wherein an adhesive layer is provided on at least one surface of the base film of the wafer full-cut dicing tape according to claim 1 or 2.