MXPA98000319A - Adhesives and tapes for the processing of semiconductor pads - Google Patents

Abstract

The present invention relates to a semiconductor wafer processing belt comprising a permanent backing and a layer of a non-pressure sensitive adhesive comprising a thermoplastic, elastomeric block copolymer on the permanent backing. Optionally, the adhesive may include an adhesion modifier such as a tackifying resin, a rubber or liquid rubber or a photo-crosslinking agent. The tapes are useful for operations both polishing the pads and fragmentation of the pads. A method of processing the semiconductor pellets is also described

Description

ADHESIVES AND DK TAPES PROCESSING OF SEMICONDUCTOR PADS BACKGROUND OF THE INVENTION Field of the Invention This invention relates generally to adhesive compositions and tapes useful for the processing of semiconductor wafers and, more specifically, to adhesive compositions and tapes that include a thermoplastic elastomeric block copolymer and which are useful in the polishing and fragmentation of semiconductor wafers.

Description of Related Art Semiconductor integrated circuit (IC) chips are commonly used in electronic components, whether for sophisticated industrial machinery, automobiles or common household appliances. The production of semiconductor IC chips begins with the manufacture of semiconductor chips containing many semiconductor elements. Finally, the chip is cut or broken into individual semiconductor elements (called matrices or dies, each member or element becomes a semiconductor IC chip.) Typically, a semiconductor chip is prepared by cutting or dividing a chip. Single-purity silicon bar or bar, single, in thin circular pellets approximately 500 to 1000 μm thick A pellet can be impurified to alter its electrical properties Electronic circuits are then applied to the front side of the pellet, usually by photolithography The separation lines are photolithographed on the tablet to provide cutting marks for a saw for the eventual fragmentation of the pellet into individual semiconductor IC chips The diameters of the pellets were traditionally approximately 76 to 102 mm (7.62 mm). or 10.16 cm (3 or 4 inches)) However, as the individual IC pellets have become larger, the diameter of the typical pellet has been increased to approximately 127 to 203 mm (5 to 8 inches) to allow more than one matrix to be formed from the single pellet. It has been expected that the diameters of the pellet will eventually expand to approximately 305 to 406 mm (12 to 16 inches), and perhaps to even larger sizes. To protect delicate electronic circuits from air pollution by dust, moisture, airborne corrosive acids and the like, the front side of the chip is provided with a passivating layer which can be an inorganic material such as oxynitride. of silicon or an organic material such as polyimide. To facilitate the manufacture of the electronic components, it is desirable to reduce the thickness of the pads (and consequently the thickness of the semiconductor IC pads formed therefrom). A common process involves holding the front side of the tablet against a vacuum table while polishing the back or back of the tablet to a thickness of approximately 200 to 500 μm in the presence of a water spray to remove the waste from the tablet. polished. However, the tablets are inherently brittle and susceptible to breakage during the polishing process, a problem which is improved when the diameter of the tablet becomes larger. In addition, the polishing process of the tablet generates dust that can contaminate electronic circuits. In addition, the front side of the chip is held against the vacuum table which could subject the passivating layer and the underlying circuits to abrasion. Consequently, there is a need to protect the chip (especially the front side) from breaking, contamination and abrasion. Initial approaches to this problem used a layer of paraffin wax on the front side of the tablet, with the wax being removed eventually by a solvent wash. The shortcomings of this approach are described in Pat. U.S. No. 4,853,286 (Narimatsu et al.). In other approaches, a photoprotective coating was coated by centrifugation on the front side of the tablet, but this did not always eliminate the rupture of the tablet. More recently, pressure sensitive adhesive tapes (PSA) have been used to protect the front side of the tablet. Sometimes PSA tapes are used alone and sometimes they are used in conjunction with a photoprotective coating to provide a surface to which the PSA tape can stick. However, according to the technical literature, the adhesive tapes have not provided a complete solution to the problem of the protection of the pads. Pat. U.S. No. 4,853,286 mentioned previously indicates that the rupture of the pellet still occurs and that the adhesive surface accumulates dust that can contaminate the pellet.

European Patent Publication No. 0 530 729 describes the difficulty in the subsequent removal of the PSA tape if it has a high initial adhesion to the tablet or if the adhesion increases from the time in which the tape is applied to the tablet. until it is removed. Various adhesive tapes that are reported to be useful in the polishing operations of the back side of the semiconductor wafer (sometimes referred to as the "pad polishing" -) have already been described. For example, Pat. U.S. No. 4,853,286 mentioned above discloses a pellet processing film which is used in the polishing of pellets to prevent rupture. The film includes a base film, a common adhesive layer, commercially available (such as an acrylic, ester, urethane or synthetic rubber adhesive), and an optional backing film laminated to the non-adhesive side of the base film. The U.S. Patent No. 5,126,178 (Ta emura et al.) Discloses a pellet processing film that includes a base film with a pressure sensitive adhesive on one side (which is protected by a removable release film), and a surfactant based on phosphoric acid on the back side. The pressure sensitive adhesive may be acrylic based, vinyl based, or rubber based, although a pressure sensitive adhesive of the aqueous emulsion type is preferred. In U.S. Pat. No. 5,183,699 (Takemura et al) describes a pellet processing film which is used when the pellets are polished to prevent rupture. The pellet processing film includes a base film and an adhesive layer (eg, a conventional acrylic or rubber-based adhesive) on the base film. A synthetic resin film, which has a surface roughness no greater than 2 μm, is arranged or distributed over the adhesive layer. European Patent Publication No. 0 252 739 discloses adhesive sheets which are applied to the front side of the semiconductor wafers in the course of polishing the reverse side of the wafers. The adhesive sheets include a base sheet and a layer of a water-soluble adhesive, which can be swollen with water, consisting essentially of a copolymer of a monomer containing unsaturated carboxylic acid and a monomer of the acrylic ester type. . European Patent Publication No. 0 530 729 discloses a pressure sensitive adhesive tape used in polishing the back side of a semiconductor wafer. The pressure sensitive adhesive, which has been reported to have a small initial adhesion and does not show an increase in adhesion strength over time, comprises an aqueous acrylic resin emulsion adhesive, a nonionic surfactant, an crosslinking agent of the epoxy and / or aziridine type, and a water soluble organic compound. Japanese Kokai Patent Application No. 62-58638 discloses an element for protecting the shaped surface of a semiconductor wafer when the back side of the wafer is polished. The protective element includes a moisture resistant sheet having a high elastic modulus and high dimensional stability. A pressure sensitive adhesive (eg, an acrylic, rubber, polyvinyl ether or urethane type adhesive) is deposited on the moisture resistant sheet. However, there is still a need for an adhesive tape having a greater utility in the polishing processes of the semiconductor wafer. Preferably, such tapes will possess several desirable properties. For example, the tape should rapidly provide initial adhesion to surfaces such as silicon, polyimide, silicon oxynitride and photoprotection coatings such that the semiconductor wafers will easily resist the post-processing steps still being easily removed when require Preferably, a single belt will provide acceptable initial adhesion to each of these surfaces to eliminate the need for storage of the different belts for the different surfaces. However, the final adhesion should not be so high that the removal of the tape will break or fracture a larger number of pellets than is allowed by conventional industry standards (typically approximately one pellet or less per thousand), or leave an adhesive residue that could damage the subsequent processing of the tablet. It could also be desirable if the initial and final adhesion properties of the tape were maintained for several days and, more preferably, for several weeks of storage. That is, there should not be a limiting increase in the process or material in adherence over time (sometimes as an accumulation of adhesion), a problem associated with certain PSA 's. Similarly, there should be no other significant change in adhesion, as could occur if the surfactants and other movable components in the adhesive migrate to the bond line of the adhesive so that a weak bond layer is formed. An adhesive that maintains its initial and final adhesion properties during storage could not only provide tapes having prolonged storage durations, but could also minimize the need to carry out the polishing process briefly after drilling the semiconductor pads. Another desirable attribute could be the ability to remove the adhesive tape without dyeing, which refers to a change in the optical density of the semiconductor wafer that is detected when the semiconductor wafer is observed under a microscope and which may be the result that microscopic amounts of the adhesive residue are left on the passivating layer during the partial removal of the passivating layer. It could also be useful if the adhesive is insensitive to water to prevent the tablet from being loosened by the water spray used during polishing. Following the polishing of the tablet, there are typically several intermediate manufacturing steps before the semiconductor wafers are cut or fragmented into individual semiconductor IC chips. Fragmentation of the tablet is conventionally carried out by fixing the polished back side of the tablet to the adhesive surface of a PSA tape (often called fragmentation tape), fixing or securing the tablet drilled to a vacuum table to restrain it against the movement, and using a rotating diamond saw sprinkled with water for cutting along the marks of the previously photolithographed saw on the semiconductor wafer. The individual semiconductor IC chips are then removed from the tape for fragmentation. This operation is usually facilitated by a needle or probe that pushes against the backing of the fragmentation tape in the area of the IC chip while a vacuum reception simultaneously holds the top of the IC chip to remove it from the tape. of fragmentation. The removed IC chips can then be further processed immediately, or they can be stored for later assembly in a finished article. The prior art publications describe several difficulties encountered when using fragmentation adhesive tapes. For example, European Patent Publications Nos. 0520 515 and 0 157 508 disclose the need for a sufficient level of addition to allow the semiconductor wafers to stick to the tape in a manner not too strong to prevent removal of the wafers. of IC fragmented. Adhesive tapes for use in chip breaking operations have been previously described. For example, European Patent Publication No. 0 520 515 mentioned above discloses a tape which is used to fix or secure the semiconductor wafers which are cut into individual configurations to form separate semiconductor wafers. The tape includes a radiation-curable pressure sensitive adhesive on a surface of a three-layer laminated support film. Preferably, the pressure sensitive adhesive contains an acrylic adhesive, a cyanurate or isocyanurate compound, and a polyester or a polyol urethane acrylate. European Patent Publication No. 0 588 180 discloses a fragmentation tape which includes a radiation transparent film and a radiation-curable pressure sensitive adhesive containing an initiation of the copolymerized radiation. The pressure sensitive adhesive can be synthesized from (meth) acrylic acid, (meth) acrylic ester, vinyl acetate or various alkyl vinyl ether monomers. The Japanese Kokai Patent Application No. 62-121781 discloses a fragmentation film of the semiconductor wafer in which a conventional pressure sensitive adhesive is applied to a polymeric film of the butene type. The Japanese Kokai Patent Application No. 5-230426 discloses an adhesive tape for chip fragmentation that includes an adhesive layer (especially an acrylic-type adhesive) or a base film made of a rubber-like elastic material. The prior reference to European Patent Publication No. 0 157 508 discloses a thin adhesive sheet which is used to protect a semiconductor wafer during the polishing step or to fix the wafer when cutting and separating the semiconductor wafer into the wafer chips. IC element. The adhesive sheet includes a light-permeable support and a pressure-sensitive adhesive which can be cured by irradiation of light to form a structure of the three-dimensional network. The adhesive comprises a mixture of a pressure sensitive adhesive based on rubber or acryl base, a photopolymerizable compound, and a photopolymerization initiator. However, there still remains a need for an adhesive tape that has an even greater utility in the fragmentation processes of the semiconductor wafer. Preferably, such tapes will possess several desirable properties. For example, the tape should provide sufficient initial adhesion to the silicon wafer (as well as other surfaces to which the tape may need to adhere such as gold-plated or stainless steel machine parts) such that the wafers The resulting semiconductor ICs will not become loose during fragmentation of the pellets. However, the final adhesion should not be too high so that the semiconductor IC chips will fracture or break during the removal of the tape in a larger number than is allowed under the conventional industrial standard. It could be desirable if the initial and final adhesion properties were maintained for several days and, more preferably, for several weeks of storage since several days or weeks may pass between the time that the semiconductor wafers were attached or fixed to the tape. of fragmentation and at the time in which the semiconductor IC chips are removed from the tape after drilling. If the adhesion increases substantially over time, it may be necessary to remove the semiconductor IC chips from the tape and store them, unless they have to be used immediately after the fragmentation. The semiconductor IC chip should also be removed cleanly from the adhesive tape so as not to leave adhesive residue that could interfere with subsequent processing such as welding or packing the IC chips. It could also be advantageous if the tape adhesive does not stick to the saw blade because this could require periodically interrupting the pickup fragmentation operation to clean the accumulated adhesive residue from the blade to prevent contamination of the IC chips. semiconductors. As well, if the adhesive does not stick to the saw blade, then it could be possible to use a thicker layer of the adhesive which could be advantageous to prevent the saw blade inadvertently cutting the backing of the belt. If the backing of the tape is partially cut during chip fragmentation, the tape could be weakened and prematurely broken during subsequent processing. The adhesive must also be insensitive to water to prevent too many pads from being loosened by spraying with water used in the fragmentation process. Finally, it could be advantageous to have a simple adhesive tape that could be used in the operations of both polishing the tablet and fragmentation of the tablet to eliminate the need to store different tapes for different processes.

BRIEF DESCRIPTION OF THE INVENTION This invention relates in general to adhesive compositions and tapes useful for the processing of semiconductor wafers, including both polishing and fragmentation of semiconductor wafers. Preferred adhesive compositions and bar processing tapes of the invention provide low initial adhesion to important substrates such as photoprotective layers, polyimide passivating layers, passivating layers of silicon oxynitride and silicon. Preferred embodiments show a minimum adhesion accumulation over time so that the semiconductor wafers and / or semiconductor IC wafers can be easily removed from the tablet processing tapes and without leaving visible amounts of the adhesive residue. In one embodiment, the invention provides a semiconductor wafer processing ribbon comprising a permanent backing and a layer of a pressure sensitive adhesive on the permanent backing. The adhesive comprises a block copolymer of thermoplastic elastomer. Preferably the adhesive has a storage module at room temperature that is greater than 1 x 106 Pascals. The thermoplastic elastomeric block copolymer comprises segments of a thermoplastic material (preferably styrene in an amount of about 5 to 30%, more preferably about 8 to 25%, more preferably 15 to 25%) and segments of an elastomer of rubber. Examples of the thermoplastic elastomeric block copolymers include those having styrene blocks and ethylene / propylene blocks such as the styrene-ethylene / propylene-styrene block copolymer and the styrene-ethylene / propylene-styrene-block copolymer. ethylene / propylene The preferred semiconductor wafer processing tapes according to the invention exhibit a peel adhesion of about 0.79 to 19.7 (more preferably about 0.79 to 7.9 kilograms per linear meter of width [20 to 500 (more preferably, in the form approximate 20 to 200) grams per linear inch of width] for one of the following substrates: silicon, polyimide, silicon oxynitride, and photoprotective coatings, and maintains this level of adhesion even after fixation or drying in contact with the substrate during 7 days under ambient conditions To provide the required adhesion to the substrate of interest, it may be desirable to include an adhesion modifier in the adhesive, such as a tackifying resin (typically less than 10% by weight, based on the combined weight of the adhesive). block copolymer of the thermoplastic elastomer and the tackifying resin, more preferably 3 to 8% by weight), a rubber or liquid rubber (typically less than 20% by weight based on the combined weight of the block copolymer of the thermoplastic elastomer and the rubber or liquid rubber, more preferably in about 5% to less than 20% by weight), or an photocrosslinking The tackifying resin and the rubber or liquid rubber adhesion modifiers are particularly useful where the thermoplastic, elastomeric block copolymer is hydrogenated. A photocrosslinking agent is particularly useful where the thermoplastic elastomeric block copolymer is not hydrogenated. A further embodiment of the invention provides a semiconductor wafer processing tape comprising a permanent backing and a layer of a non-pressure sensitive adhesive on the permanent backing, wherein the adhesive comprises a thermoplastic, hydrogenated, elastomeric block copolymer , which exhibits a storage module at 20 ° C from 2.7 x 106 to 4.0 x 106 Pascals. Styrene-ethylene / propylene-styrene and styrene-ethylene / propylene-styrene-ethylene / propylene block copolymers are particularly preferred in this embodiment. A particularly preferred aspect of the invention provides a chip fragmentation tape having the constructions described above. Such tapes can advantageously have relatively thin backings of about 15 to 50 μm (more preferably in approximately 12 to 25 μm form)., more preferably in approximately 12 to 15 μm form), such backs can have an elongation at break of about 100 to 200% (more preferably about 120 to 165%) in the machine direction. Advantageously, these chip fragmentation tapes can provide a peel adhesion of about 0.79 to 7.9 kilograms per linear meter of width (20 to 200 grams per linear inch of width) both at the time of applying the tape to a semiconductor wafer as after drying in contact with the tablet for 15 days under ambient conditions. The invention also relates to a method for processing a semiconductor wafer. The method comprises the steps of: (a) providing a semiconductor wafer; (b) adhesively bonding the semiconductor wafer to the adhesive surface of a semiconductor wafer processing strip comprising a permanent backing and a layer of a non-pressure sensitive adhesive on the permanent backing; and (c) processing the semiconductor wafer either by polishing the back side of the wafer or by fragmenting the wafer into the semiconductor wafers of the integrated circuit. The adhesive comprises an elastomeric, thermoplastic block copolymer, such as those described above.

DETAILED DESCRIPTION OF THE PREFERRED MODALITIES This invention relates in general to adhesive compositions and adhesive tapes that are useful in tablet processing applications, including the processes of pad polishing and chip fragmentation. "Buffing the bar" as used herein, refers to the process of polishing the back side of a semiconductor wafer to reduce its thickness, a well-known process in the manufacture of semiconductor wafers. "Fragmentation of the pellet" as used herein, refers to cutting with a saw or fragmentation of a semiconductor pellet into individual matrices or semiconductor IC chips, which is also a well-known step in the conversion of the semiconductor pellets into the pellets. IC chips. Preferred adhesive compositions and chip processing tapes of the invention provide a low final adhesion to the important semiconductor industrial substrates such as photoprotective layers, organic passivating layers (e.g., polyimide), inorganic passivating layers (eg. example, the silicon oxinitrute), or silicon. Preferred embodiments show a minimum adhesion build-up over time so that the semiconductor wafers and / or semiconductor IC wafers can be easily removed from the wafer processing tapes of the invention without breaking or fracturing in numbers larger than those allowed by industry standards and without leaving visible quantities (at a glance) of adhesive residue. The highly preferred embodiments of the invention exhibit these attributes for several, and more preferably, for all of the surfaces of the aforementioned substrates. The highly preferred embodiments of the invention can also be removed from semiconductor wafers and / or semiconductor IC chips without dyeing. In one aspect, the tablet processing tapes of the invention comprise a permanent backing and a layer of a non-pressure sensitive adhesive (non-PSA) on the permanent backing, wherein the non-PSA comprises an elastomeric block copolymer, thermoplastic By "permanent backing" is meant a substrate or backing layer which is intended to form an integral part of the tablet processing belt rather than being a removable or releasable component, such as a protective, temporary release coating. . In order to promote a wide utility in the processing tapes of the tablet of the invention, the permanent backing will desirably possess various properties. For example, the permanent backing must be flexible enough to allow it to be wound around a core in the form of a roll for easy handling, storage and shipping. Also, the permanent backing must have the ability to be cut by a knife to allow the manufacture of wide continuous rolls that can be cut or subsequently slotted to narrower widths that can be used more easily, as well as to accommodate the manufacturing steps of the semiconductor IC chip that will require the permanent backup to be cut. Preferably, the permanent backing will not contain more extractable compounds with water or ionic components than those that are allowed under the industrial standards of tablet processing and, more preferably, will be free of such materials to reduce the water sensitivity of permanent backing and reduce the likelihood that the semiconductor wafers will become contaminated by these materials. The permanent backs useful in the processing tapes of the tablet of the invention can be provided as a single-ply film or as a multi-ply film. The thickness of the backing can vary widely as long as the resulting tape can be easily handled by the polishing equipment of the tablet and the fragmentation of the tablet. Within these guidelines or guides, the thickness of the permanent backing is typically about 5 to 500 μm, although for chip fragmentation tapes it is more preferred that the permanent backing has a thickness of about 12 to 50 μm, more preferably a thickness of about 12 μm. at 25 μm, and more preferably a thickness of about 12 to 15 μm. Also, the tablet processing tapes specifically proposed for use in fragmentation applications are preferred to be sufficiently stretchable so that they can accommodate the use of a push or pull needle or probe that can be employed to facilitate the Removal of a semiconductor matrix. Accordingly, the preferred permanent backs for use in the chip fragmentation tapes exhibit a tensile strength at the machine direction break of about 70 to 240 kiloPascals (kPa) and, in the transverse direction, about 100 to 300 kPa. Similarly, the elongation in the machine direction at the breaking of the preferred permanent backs for use in chip fragmentation applications is from about 100 to 200% (more preferably in the approximate 120 to 165% form), and approximately 30 to 90% in the transverse direction. Permanent backings having a tensile strength less than this range or an elongation greater than this range, will be further stretched when contacted with a probe for the removal of the semiconductor IC chip than the preferred permanent backings of the invention for use in the processes of fragmentation of the tablet. As a result, such backups that are not within the preferred ranges can lead to slower manufacturing speeds since the distance the probe travels will be increased. In addition, when the rigidity of the permanent backing is increased (ie, the high tensile strength, low elongation) it is easier to handle the larger diameter semiconductor chips that become more common. The materials from which the permanent backs useful in the processing tapes of the bar of the invention can be made, include polyolefins (for example polyethylene, polypropylene, polybutene and polymethylpentene), ethylene / vinyl copolymers (for example copolymers) ethylene / (meth) acrylic acid and ethylene / vinyl acetate copolymers), polybutadiene, poly (vinyl chloride), polyurethane, polyamine, and polyester (especially polyethylene terephthalate). Adhesive compositions useful in the invention are the non-PSA (non-pressure sensitive adhesive) materials they comprise and, more preferably, consisting essentially of an elastomeric, thermoplastic block copolymer. By a "non-PSA" is meant an adhesive that does not exhibit pressure-sensitive properties. A pressure sensitive adhesive is conventionally understood to refer to an adhesive that exhibits permanent and aggressive tackiness with respect to a wide variety of substrates after the application of only light pressure. An accepted quantitative description of a pressure-sensitive adhesive is given by the Dahlquist criteria line, which indicates that materials having a storage modulus (G ') of less than about 3 x 10 5 Pascals (measured at 10 radians) / second at room temperature, approximately 20 to 22 ° C) have pressure-sensitive properties, while materials that have a G 'in excess of this value do not. Accordingly, more specifically, a non-PSA, as used herein, refers to a material having a storage module at least above the Dahlquist criteria line, and more preferably, a storage module above 1 x 106. Pascals By "elastomeric, thermoplastic block copolymer" is meant a block copolymer or segments A and B segmented and which exhibit both thermoplastic and elastomeric (ie, rubber type) behavior. For reasons of simplicity, the terms "thermoplastic elastomer" and "block copolymer" as they are sometimes used herein, refer to an elastomeric, thermoplastic block copolymer. Therefore,. A thermoplastic elastomer can be easily distinguished from natural and synthetic rubbers or rubbers as well as conventional thermoplastics (for example, acrylates and vinyls). The thermoplastic elastomers useful in the adhesive compositions and bar processing tapes of the invention include multi-block copolymers having linear A-B, and triblock A-B-A, radial structures, as well as mixtures of these materials. In these structures A represents a thermoplastic segment different from the rubber or rubber (for example a final block) and B represents an elastomeric segment of rubber or rubber (for example, an intermediate block). However, small proportions of other monomers can be introduced into the block copolymers. Exemplary thermoplastic A blocks include mono and polycyclic aromatic hydrocarbons, and more particularly, mono and polycyclic lows. Exemplary mono and polycyclic loops include substituted and unsubstituted poly (vinyl) lobes of the monocyclic and bicyclic structure. Preferred thermoplastic elastomers include substituted and unsubstituted monocyclic and unsubstituted thermoplastic segments of sufficient segment molecular weight to ensure phase separation at room temperature. The thermoplastic A blocks may comprise a homopolymer or copolymer of the alkenyl brines. The lower alkenyl in the thermoplastic A blocks are preferably monoalkenyl-arene. The term "monoalkenyl arene" will be taken to particularly include those from the benzene series such as styrene and its analogs and homologs, including o-methylstyrene, p-methylstyrene, p-tert-butylstyrene, 1,3-dimethylstyrene, alpha -methylstyrene and other styrenes rented in the ring, particularly styrene-methylated in the ring, and other mono-alkenyl polycyclic aromatic compounds such as vinyl naphthalene, vinyl anthracene and the like. Preferred monoalkenyl-halides are the monocyclic monovinyl loins such as styrene and alpha-methylstyrene, and styrene is particularly preferred. The individual thermoplastic A blocks have a number average molecular weight of at least about 6,000 so as to promote good domain formation and, more preferably, a number average molecular weight of about 8,000 to 30,000. The thermoplastic A blocks typically constitute about 5 to 30 percent, and preferably, about 8 to 25 percent by weight of the block copolymer. When the B blocks are comprised of an elastomeric segment of saturated rubber, the most preferred thermoplastic elastomers contain A blocks which constitute approximately 15 to 25% by weight of the block copolymer. The ABA designation includes block copolymers that are branched as well as linear and also include structures in which the end blocks are different from each other but both are styrene derivatives or styrene homologs (such structures are sometimes referred to as copolymers). ABC blocks). Preferred rubber elastomer segments B are block copolymers composed of the homopolymers of a monomer or the copolymers of two or more aliphatic conjugated diene monomers. The conjugated dienes are preferably ones containing from 4 to 8 carbon atoms. Examples of suitable conjugated diene monomers include 1,3-butadiene (butadiene), 2-methyl-1,3-butadiene (isoprene), 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene. (piperylene), 1,3-hexadiene, and the like. In the most preferred styrenic block copolymers, the rubber segments can be saturated by the hydrogenation of unsaturated precursors such as the styrene-butadiene-styrene block copolymer having core blocks comprising a mixture of isomers 1, 4 and 1.2. During the hydrogenation of the latter, a styrene-ethylene / butylene-styrene block copolymer is obtained. Similarly, a styrene-isoprene-styrene block copolymer precursor can be hydrogenated to give a styrene-ethylene / propylene-styrene block copolymer. Rubber materials such as polyisoprene, polybutadiene and styrene-butadiene rubbers can also be used to form the elastomeric rubber segments. Also preferred are butadiene and isoprene. Mixtures of different conjugated dienes can also be used. The number average molecular weight of the B blocks of the linear diblock and triblock copolymers is preferably in the range of about 4,500 to 180,000. The radial block copolymers useful in this invention are of the type described in U.S. Pat. No. 3,281,383 and the following general formula (AB) nB are formed, wherein A is a polymerized thermoplastic block from styrene or homologs styrene, B is an elastomeric rubber block derived from conjugated dienes, as indicated above, X is an organic or inorganic connecting molecule with a functionality of 2-4 such as silicon tetrachloride, tin tetrachloride, or divinyl benzene, although others are mentioned in US Pat. No. 3,281,383. X may have a higher functionality in which still "n" is a number corresponding to the functionality of A. The numerical average molecular weight of the radial block copolymers is preferably in the range of about 125,000 to 400,000. The thermoplastic elastomer may also comprise a mixture of radial or linear triblock copolymers and simple diblock copolymers. However, the proportion of the diblock copolymers in the mixture of the diblock and triblock copolymers should not exceed about 85 weight percent and usually lower percentages such as 30% could be used.

A wide variety of commercially available thermoplastic elastomers can be used (either alone or in combination) in the invention, including the SOLPRENE family of materials (Phillips Petroleum Co.), the FINAPRENE family of materials (Fine), the TUFPRENE families and ASAPRENE of materials (Asahi), the STEREON family of materials (Firestone Synthetic Rubber &Latex Co.), the family EUROPRENE SOL T of materials (Enichem), the VECTOR family of materials (Dexco Polymers), and the CARIFLEX TR family of materials (Shell Chemical Co.). Also useful is the SEPTON family of materials (Kuraray Co. Ltd), such as SEPTON 2002, 2005, 2007, 2023, 2043 and 2063. The KRATON family of materials (Shell Chemical Co.), such as D-1101, is also useful. , D-1102, D-1107P, D-llll, D-1112, D-1114PX, D-1116, D-1117P, D-1118X, D-1119, D-1122X, D-1124, D-1125PX, D -1184, D-1300X, D-1320X, 4141, 4158, 4433, RP-6408, RP-6409, RP-6614, RP-6906, RP-6912, G-1650, G-1651, G-1652, G -1654X, G-1657, G-1701X, G-1702X, G-1726X, G-1750X, G-1765X, FG-1901X, FG-1921X, FG-1924, and TKG-101. In general, the KRATON series of hydrogenated thermoplastic elastomers is preferred. One class of materials which is highly preferred are hydrogenated block copolymers comprising styrene segments and ethylene / propylene segments, especially those which have a reported binding efficiency of 100%, which are approximately 15 to 25% (yet more preferably about 18 to 23%) of styrene, a tensile strength of about 3100 psi, and about 9% adjustment at the point of rupture. Such materials can exhibit the following module profile in storage (at 10 radians / second): approximately 2.5 x 106 to 4.0 x 106 Pascal at 0 ° C, approximately 2.7 x 106 to 4.0 x 106 Pascal at 20 ° C, and approximately 2.9 x 106 to 3.8 x 106 Pascals at 40 ° C. Representative of this class of materials are KRATON RP-6906 and RP-6912, the latter being particularly unique as a linear, multi-block copolymer having four separate blocks (styrene-ethylene / propylene-styrene-ethylene / propylene). Mixtures of these materials are also useful. This class of materials advantageously provides a level of usefulness of the adhesion without adding adhesion modifiers. Certain of these thermoplastic elastomers useful in the invention may have inherent levels of adhesion that are either too low (especially certain hydrogenated thermoplastic elastomers) or too high (especially certain unhydrogenated thermoplastic elastomers) for maximum utility in tablet processing applications. . In addition, certain of the thermoplastic elastomers may insufficiently wet the surface of the substrate to be bonded, may form a low quality coating, may be difficult to coat, or a combination thereof, for better utility in processing applications. of the pill. Accordingly, the adhesive compositions of the invention may additionally and optionally comprise an adhesion modifier such as a tacky resin or a liquid rubber to increase the inherent adhesion, the wettability or the coating capacity of the thermoplastic elastomer, or a photo-crosslinking agent. to decrease the inherent adhesion of the thermoplastic elastomer. Sticky resins can be added to the thermoplastic elastomer to improve the adhesion resistance thereof and to decrease the modulus thereof to improve the ability of the adhesive composition to rapidly wet the surface of the substrate to which they are applied. Sticky resins can also impart other desirable properties to the adhesive composition such as lower viscosity, improved coating ability, and adhesion during the improved release.

Sticky resins useful in the adhesive compositions of the invention include resins derived by the polymerization of the monomers of unsaturated hydrocarbons with 5 to 9 carbon atoms, polyterpenes, synthetic polyterpenes, and the like. Sticky resins may contain an ethylene unsaturation; however, saturated sticky resins are especially preferred for use with hydrogenated thermoplastic elastomers. Sticky hydrocarbon resins can be prepared by the polymerization of monomers consisting mainly of olefins and diolefins and include, for example, monomers of residual by-products of the isoprene manufacturing process. These sticky hydrocarbon resins typically exhibit ball and ring softening points from about 80 ° C to 145 ° C, acid numbers from about 0 to 2, and saponification values of less than one. Sticky resins useful in the adhesive compositions of the invention are typically low molecular weight materials; for example, a weighted average molecular weight of about 350 to 2,500. It is also preferred that the tackifying resins are compatible with the thermoplastic elastomer, whereby it is understood that there is no visible evidence of phase separation of these components at room temperature.

Examples of commercially available tackifying resins useful in the adhesive compositions of the invention and which are based on a 5-carbon olefin fraction, include ingtack® 95 and ingtack® R 115 (Wingtack Plus) which are sticky resins available from Goodyear Tire and Rubber Co. Other hydrocarbon resins include Regalrez® 1078, Regalrez® 1094 and Regalrez® 1126 available from Hercules Chemical Co., Inc .; Arkon resins, such as Arkon R P115, available from Arakawa Forest Chemical Industries; and Escorez R resins available from xxon Chemical Co. Examples of the rosin derivatives, especially hydrogenated derivatives, which are useful in the invention include Foral R 85 and Foral R 105 from Hercules Chemical Co., Inc. Other suitable resins include polymers of terpene, such as polymeric resinous materials obtained by polymerization and / or copolymerization of terpene hydrocarbons such as alicyclic, mono, and bicyclic monoterpenes and mixtures thereof, including carene, isomerized pinene, terpinene, turpinene, and various other terpenes. Commercially available resins of the terpene type include the Zonape R terpene B series and the 7000 series available from the Arizona Chemical Corp. Typically the properties reported for the Zonarez R terpene resins include ball and ring softening points of approximately 80. at 145 ° C, and saponification numbers of less than one. The tackifying resins used in an effective amount, which is a quantity proposed to give the appropriate level of adhesion to the substrate of interest. The actual amount of the tackifying resin employed will depend on the level of adhesion desired, the substrate to be bonded, and the modulus of the thermoplastic elastomer. An insufficient amount of sticky resin can not lead to an adequate increase in adhesion. On the other hand, the tackifying resin should not be employed in an amount which will lead to an unacceptably high level of final adhesion because this would cause an unacceptably high level of rupture of the semiconductor wafer during the removal of the wafer processing tape. In general, the minimum amount of tackifying resin necessary to achieve the desired adhesion while maintaining the non-PSA character of the adhesive, is employed, which is an amount that is typically less than 10% by weight based on the combined weight of the sticky resin and the thermoplastic elastomer. More preferably, about 3 to 8% by weight is used. Alternatively, a liquid rubber can be used to increase the strength of the initial adhesion of the adhesive composition, decrease its modulus, and improve its ability to wet the surface to be joined. The liquid rubber must be selected to be compatible with the thermoplastic elastomer, so it is understood that there is no visible evidence of phase separation at room temperature. The molecular weight of the liquid rubber should be selected to inhibit the likelihood of the liquid rubber migrating to the adhesive bond line, which could cause a weak boundary layer and premature failure of the chip processing belt. A molecular weight of approximately 25,000 to 50,000 is useful. Although partially hydrogenated liquid rubbers can be used, those that are more fully hydrogenated are preferred, such as hydrogenated liquid isoprene rubber (eg, Kuraray LIR 290, which has a molecular weight of approximately 25,000 Kuraray Co. Ltd.) . The liquid rubber must be used in an effective amount, which is an amount that is selected by the same criteria described above in conjunction with the sticky resin. Within these parameters, a typical amount of the liquid rubber is less than 20% by weight, based on the combined weight of the thermoplastic elastomer and the liquid rubber, more preferably from 5 to less than 20% by weight.

On the other hand, if the final adhesion of the thermoplastic elastomer is too high to allow a facilitated removal of the pellet processing tape, then it may be appropriate to add a photocrosslinking agent to reduce the final adhesion of the thermoplastic elastomer. When used herein, a "photocrosslinking agent" refers to an agent which, during exposure to ultraviolet radiation (e.g., radiation having a wavelength of about 250 to 400 nanometers), causes the elastomer thermoplastic reticulate. Photocrosslinking agents suitable for use in the invention include aldehydes, such as benzaldehyde, acetaldehyde, and their substituted derivatives; ketones such as acetophenone, benzophenone and their substituted derivatives such as Sandoray 1000R (Sandoz Chemicals, Inc.); quinones such as benzoquinones, anthraquinone and their substituted derivatives; thioxanthones such as 2-isopropylthioxanthone and 2-dodecylthioxanthone; and certain substituted chromophoric halomethyl-trizines such as 2,4-bis- (trichloromethyl) -6- (3 ', 4'-dimethoxyphenyl) -sym-triazine, although these latter materials are less preferred because of their potential for generate halogen pollutants.

The photocrosslinking agent is used in a curatively effective amount, by which is meant an amount that is sufficient to cause crosslinking of the adhesive to provide the desired final adhesion properties to the substrate of interest. An insufficient amount of photocrosslinking agent can cause improper curing (ie, cross-linking) of the adhesive composition such that the adhesion still remains too high, although the excess photocrosslinking agent can lead to non-uniform curing through the volume of the adhesive composition. Within these parameters, the amount of the photocrosslinking agent is typically about 0.05 to 2% by weight of the thermoplastic elastomer, more preferably about 0.2 to 1% by weight, and even more preferably about 0.3 to 0.5. % in weigh. Minor amounts of various additives may also be included in the adhesive compositions. Such additives include pigments, dyes, plasticizers, stabilizers, ultraviolet light absorbers, antioxidants, processing oils, and the like. The amount of additives used may vary depending on the desired final properties.

To provide improved utility in tablet processing applications, the tapes for chip processing must be essentially free of ionic impurities that could migrate on and contaminate the IC semiconductor chip. The adhesive compositions and the processing tapes of the tablet of the invention can be prepared easily. Typically, the thermoplastic elastomer and any tacky resin or liquid rubber are solubilized in a non-polar organic solvent such as toluene (which may be combined with minor amounts of heptane and / or cyclohexane, or equal parts by weight of the mixture of methyl ethyl ketone and isopropanol) using a roller mill or other mixing device with low shear at room temperature for several hours (typically in about 2 to 4 hours) until no undissolved visible thermoplastic elastomer is observed. If a photocrosslinking agent is included, it can be added at this time with additional mixing on the roller mill to ensure complete dissolution. The resulting solubilized thermoplastic elastomer can be diluted to a solids content (eg, about 25%) that provides a coatable viscosity (eg, from about 4,000 to 5,000 cps) using additional non-polar organic solvents of the type described above. A combination of 50% / 25% / 25% by weight of toluene / methyl ethyl ketone / isopropanol is particularly preferred as a diluting solvent. The solvent solution can then be applied to permanent backing by a variety of coating methods including knife coating, coating with slotted blades or coating with reverse rolls and then drying at a temperature (eg, from about 65 to 120 ° C) and a time (eg, several minutes to about an hour) to provide an adhesive tape. The thickness of the dry adhesive layer can vary over a wide range of about 10 to several hundred (for example, about 200) microns, although for the polishing processes of the tablet, a thickness of the dry adhesive of about 80 to 90 μm is more preferred, although a dry adhesive thickness of about 50 to 100 μm can be used for the tapes used in the chip fragmentation processes. If a photocrosslinking agent has been used, the adhesive can be exposed to ultraviolet radiation having a wavelength of about 250 to 400 nm. The radiant energy in this preferred range of wavelengths required to crosslink the adhesive is from about 100 to 1,500 millijoules / cm 2, more preferably in the approximate form of 200 to 800 millijoules / cm 2. The adhesive can be crosslinked either before or after tablet processing (eg, polishing or fragmentation). Once the adhesive composition has been dried to provide a tablet processing tape, an adhesive surface of the tape can, optionally, be protected with a temporary, removable release coating, such as a polyolefin (eg, polyethylene or polyethylene). polypropylene) or a polyester film (for example, polyethylene terephthalate), or a paper or plastic film that has been treated with a release material such as silicones, waxes, fluorocarbons, and the like. The invention will be more fully appreciated with reference to the following non-limiting examples. The examples were evaluated with respect to certain test methods which are described later. All the dimensions given in the test methods and the examples are nominal dimensions.

Test Methods Test Method A of Adhesion during Detachment Adhesion during detachment for several substrates that could be found in the tablet polishing applications was evaluated by fixing a sample of the tablet processing tape (the tape having a width of 25 millimeters and a length of approximately 130 mm. ) with two passes of a roller covered with rubber of approximately 2 kg. The substrate with the tablet processing ribbon attached thereto is then allowed to dry at 23 ° C and a relative humidity (RH) of 50% for a period of time specified in the examples as "drying". Next, the opposing surface of the substrate (i.e., the surface of the substrate does not have the tablet processing ribbon attached thereto) was securely tapered to the adhesion tester of an adhesion tester of Instrumentors, Inc., Slip-Peel Tester Model SP-102C-3M90. A free end of the test strip of the tablet processing belt is attached to the force sensor of the tension tester and the test strip was detached from the surface at an angle of 180 ° and at a speed of 30 cm / min. Adhesion during peeling was recorded in grams per linear inch of width (gliw, which approximates grams by 25 mm, or 0.03937 kilograms per linear meter of width (kgmw)) and the values reported in conjunction with the following examples They are an average of at least 2 measurements. The adhesion values in the release should be from about 0.79 to 197 klgmw (20 to 500 gliw), and more preferably in about 0.79 to 7.9 kgmw (20 to 200 gliw) to promote wide acceptance of the processing tapes of the pill in the industry semiconductor wafer manufacturers. Preferably the adhesive compositions show a minimum adhesion build-up over time; that is, a final adhesion that is still within these ranges. If the pellet processing tapes were considered removable, they were also evaluated qualitatively. A tape was considered removable if it could be removed from the substrate without breaking or fracturing, and if there is no adhesive residue visible to the naked eye on the substrate. The substrates against which the adhesion in the release is measured were: (1) smooth polyimide (which has been applied to a smooth surface semiconductor silicon wafer); (2) a IC polyimide passivating layer representative of those conventionally used in the manufacture of semiconductor IC chips (which have been applied to a semiconductor silicon wafer having photolithographed electronic circuits thereon such that exposed surfaces) for the union were both polyamide and electronic circuit materials); (3) an epoxy-based photoprotective layer (representative of those commonly used in the manufacture of semiconductor wafers) which have been coated on the IC polyimide passivation layer described now); and (4) an IC silicon oxynitride passivator layer representative of those conventionally used in the manufacture of conductive IC chips (which have been applied to a semiconductor silicon wafer having photolithographed electronic circuits thereon in such a way that the exposed surfaces for the union were both silicon oxynitride and electronic circuit materials).

Test Method B of Adhesion during Detachment Adhesion during detachment for several substrates that could be found in the tablet fragmentation applications were also evaluated. The test strips of the pellet processing tape measuring approximately 115 mm x 19 mm were cut with a fixed blade razor and adhesively bonded to a smooth surface semiconductor silicon wafer, floating glass and substrates of 315 grade stainless steel with 2 passes of a roller coated with rubber of approximately 2 kg. The surfaces of the substrate were precleared with diacetone alcohol applied with a lint-free cloth, then rinsed in heptane and dried. The samples were conditioned at 21 ° C and 55% RH for a period of time specified in the examples as "drying". Adhesion during detachment was measured on an adhesion tester Instrumentors, Inc. Slip-Peel Tester Model SP-102C 3M90. A free end of the test strip of the pellet processing tape was attached to the force sensor of the adhesion tester and the test strip was detached from the substrate at an angle of 180 ° at a speed of 30 cm / min. . Adhesion during detachment was recorded in kilograms per linear meter of width (kgmw [grams per linear inch of width (gliw)] and the values reported in conjunction with the following examples are an average of 5 measurements. of the pellet, the adhesion during peeling is preferably in the form of about 0.79 to 7.9 kglmw (20 to 200 gliw), more preferably about 1.64 to 5.91 kglmw (40 to 150 gliw), and more preferably about 3.94 kg (100 gliw), although actual adhesion may depend on the size of the matrix, smaller matrices often require adhesion at the largest release, preferably the adhesive composition exhibits minimal adhesion buildup over time; that is, a final adhesion that is still within these ranges.

Polishing the Passion Semiconductor The utility of the pellet processing tapes in tablet polishing applications was evaluated with a tape sample having a width at least equal to the width of a semiconductor silicon wafer. The tape was applied in a clean room of class 1000 at room temperature to the different surface of the silicon of the tablet with one pass of a roller coated with rubber of approximately 2 kg. The silicon pellet with the pellet processing tape attached thereto was then allowed to dry at ambient conditions for no more than eight hours, and usually less than one hour. The semiconductor pad with the tape was placed the tape of the descending side on the mandrel to the vacuum of a disco pad polisher Model DFG-83H / 6. In the polishing process the semiconductor wafer is passed under a series of three abrasive wheels (each available from Disco Corp.). The first grinding wheel (model No. RS-01-2-40 / 60-NA-A) removed 120 μm of silicon, the second grinding wheel (model No. RS-01-2-20 / 30-NA-C) it removed 100 μm of silicon, and the third abrasive wheel (model No. RS-03-2-2 / 34-P) removed 10 μm of silicon. The total grinding time was approximately 10 minutes. Following the third grinding wheel, the semiconductor wafer is washed with water to remove polishing debris, dried with air, and allowed to dry at ambient conditions for approximately 16 hours. Two 25 mm wide test strips of the pellet processing tape with the exposed back were cut, each approximately 12.7 mm (0.5 in.) In from the edge of the pellet, using a fixed blade razor . A 50 mm wide piece of Nitto 315S removal tape (from Nitto Denko Company) was then applied downwardly in the center of the exposed backing of the tablet processing belt using two passes of a rubber coated roller of approximately 2 kg. The removal tape attached to the middle section of the tablet processing belt between the two cut strips was then manually removed. The two pieces of the exposed back edge of the pellet processing tape were removed manually without the use of the removal tape. Next, the opposite surface of the semiconductor wafer (i.e., the surface that does not have the test strips attached thereto) is securely covered to the adhesion test wagon of an adhesion tester Instrumentors, Inc. Slip -Peel Tester Model SP-102C-3M90. One end of the test tape was attached to the strength sensor of the adhesion tester and the removal tape with the tablet processing tape was removed from the tablet at an angle of 180 ° and at a speed of 30 cm / min. . Adhesion at detachment was recorded in grams per linear inch of width and the values reported in conjunction with the examples are from a single measurement.

The pellet processing tape was considered to be peelable and therefore useful in tablet polishing applications if the tape could be removed from the semiconductor wafer without breaking or fracturing the wafer and if there was no remaining residue on the wafer that was visible to the naked eye Fragmentation of the Semiconductor Tablet The specific utility of the pellet processing tapes as tablet fragmentation tapes was evaluated by stretching a sample of 20 square mm of tape on a ring of band tape of 147 mm diameter (# 8572 by Gustav irz AG, Berg, Switzerland) and fixing the tape downwards with the external fixing ring. A 127 mm diameter polished silicon wafer having a thickness of about 0.43 mm was carefully placed on the stretched film to avoid trapping air between the wafer and the film. A gentle finger pressure along the back of the tape was used to remove any air voids. Within 30 minutes of fixing the silicon wafer, it was fragmented using an automatic Fragmentation Saw of Disco Abrasive System (Model No. DAD-2H / 5 equipped with a Saw Blade Disc NDCZ-205-L that has an external diameter of 50.8 mm and a thickness of 0.050 mm ). The fragmentation saw was operated at a speed of 25.4 mm / sec using a water wash of 2.11 kg / cm2 (30 psi) to cut the silicon pellet in the die measuring 4.3 mm by 4.3 mm on cutting centers. The number of washes of the die or matrix to remove the tape during the chip fragmentation process was recorded.

Dyeing of the Semiconductor Tablet The tendency of the tablet processing tapes to cause dyeing of the semiconductor wafer was evaluated by placing the test surface of a tablet (i.e., the surface from which the wafer processing tape was removed) under a Zeiss Axioplan Universal Semiconductor microscope equipped with a Model MM 100 of Zeiss Microscope and optically examining the entire surface under a minus 128X amplification power to verify changes in the optical density of the test surface. Any change in the optical density of the test surface was considered as dyeing. The percentage of surface area that was dyed was then estimated. In general, the presence of dyeing was considered undesirable because it can limit how widely the tablet processing tape is used.

Resistance to Traction and Percentage of Elongation in the Rupture The properties of tensile strength and elongation at break of several of the examples were tested. More specifically, the test samples were prepared by cutting test strips measuring approximately 150 mm x 20 mm using a fixed blade razor. Any release coating associated with the samples was removed prior to the test. The test samples were preconditioned at 21 ° C and 55% RH for at least four hours before measurement on an Instron Model 1122 Voltage Tester that has a load cell of 22.7 kg (50 pounds), a crosshead speed of 125 mm / minute, and a hole or vacuum of 50 mm. Samples were tested in both the machine and transverse directions, with both the tensile strength and the percentage of elongation that are measured at the break. The tensile strength was calculated in pounds per square inch as the force at the break divided by the cross-sectional area of the tape and then converted to kiloPascals (kPa). The results reported below in the examples are an average of five measurements.

Examples 1 to 11 A series of processing tapes of the tablet according to the invention was prepared. The adhesive composition used in the tablet processing tapes for each of the examples was prepared by combining 30 grams (g) of thermoplastic elastomer and 70 g of toluene in a one-quarter glass jar, closing the jar, and placing the in a roller mill until no undissolved thermoplastic elastomer was visible. The total mixing time was less than eight hours. The solution of the adhesive composition was then coated on a 50 μm thick polyethylene terephthalate film using a knife box with a breakpoint knife configured with a coating vacuum which ensured a dry adhesive coating thickness of approximately 76 μm . Once coated, the pellet processing tapes were dried for approximately 10 minutes at room temperature followed by 10 minutes at 82 ° C.

Table 1 given below shows the registered name of the thermoplastic elastomer used in each of the examples in the company of a description of the type of the thermoplastic elastomer and the percentage of styrene (% styrene) in the thermoplastic elastomer. In Table 1 (as well as in the subsequent tables), SIS refers to a styrene-isoprene-styrene block copolymer, SBS refers to a styrene-butadiene-styrene block copolymer, SB refers to a copolymer of styrene-butadiene blocks, SEBS refers to a styrene-ethylene / butylene-styrene block copolymer, SEPS refers to a styrene-ethylene / propylene-styrene block copolymer, and SEPSEP refers to a block copolymer of styrene-ethylene / propylene-styrene-ethylene / propylene. KRATON materials are commercially available from Shell Chemical Company. They are also displayed in. Table 1 the results of the adhesion test during the release (method A) where the substrate was the smooth polyimide and the drying time was 1 day, including the observations regarding the detachability of the processing tapes of the tablet.

TABLE 1 * The adhesion during the release was too high to allow the removal of the tape.

Table 1 shows that saturated thermoplastic elastomers are generally preferred for use in the invention (although Example 6 showed the buildup of adhesion over time and Example 8 did not produce a smooth surface during drying), because the Insaturadbs materials tend to give a higher adhesion. However, the levels of adhesion of the unsaturated materials could be usefully reduced by means of the incorporation of a photocrosslinking agent as described above and shown later in other examples. Although not specifically shown in Table 1, each example had a storage module above the Dahlquist criteria line.

Examples 12 to 19 A series of pellet processing tapes according to the invention was prepared following the procedure described in conjunction with examples 1 to 11 except that the thermoplastic elastomers shown below were used in Table 2. SEB (I) S refers to SEBS block copolymer having an isoprene arm or branch. SEPTON materials are commercially available from Kuraray Co. Ltd. The pellet processing belts were evaluated for adhesion during peeling (using test method A) on the substrates and with the drying times specified in Table 2, in the company of the observations about the detachment of the tapes. In these examples, the polyimide substrate was a IC polyimide passivating layer as described above. Examples 5, 6, 7, 10, and 11 were repeated in Table 2.

TABLE 2 Table 2 shows that the materials having a relatively high adhesion to the smooth polyimide in Table 1 also have a relatively high adhesion to the substrates in Table 2, although the adhesion to the photoprotective layer was often less than the adhesion to the IC passivative polyimide layer. As a class, block copolymers of SEPS are more generally preferred. Although not specifically shown in Table 2, each example had a storage module above the Dahlquist criteria line.

Examples 20 to 25 A series of tablet processing tapes according to the invention was prepared following the procedure described in conjunction with examples 1 to 11 except that the mixtures of two thermoplastic elastomers were used as shown in Table 3 below where the percentages relative to the thermoplastic elastomers are given as percentages by weight. Also shown in Table 3 are the results of method A of the adhesion test in the release in which the substrate had a passivating layer of IC polyimide, accompanied by observations about strip detachibility.

TABLE 3 Table 3 shows that the adhesion during peeling can usually be controlled by varying the type of block copolymer used in a mixture and the relative amounts of the block copolymers used in the mixture. Mixtures of different block copolymers of SEPS or mixtures of these with block copolymers of modified SEBS (for example block copolymers SEB (I) S) are preferred. Although not specifically shown in Table 3, each example had a storage module above the Dahlquist criteria line.

Examples 26 to 30 A series of tablet processing tapes according to the invention was prepared as described in conjunction with Examples 1 to 11 except that the adhesive composition was prepared by combining varying amounts of Kraton G-1650 thermoplastic elastomer and Regalrez 1094 sticky resin ( a hydrocarbon resin from Hercules, Inc.) with 115 g of toluene. The more specific information that relates to the adhesive formulations used in Examples 26 to 30 is given in Table 4 below. Also reported in Table 4 are the results of the detachment adhesion test (method A) in which the substrate had a passive polyimide layer of IC, accompanied by observations about strip detachment.

TABLE 4 Table 4 shows that a tacky resin can be useful in increasing the adhesion resistance during release of an adhesive composition. Typically, the amount is less than 10% by weight (based on the combined weight of the thermoplastic elastomer and the tackifying resin), more preferably, in the form of about 3 to 8% by weight. Although not specifically shown in Table 4, each example had a storage module above the Dahlquist criterion line.

Examples 31 and 32 A pair of tablet processing tapes according to the invention was prepared as described in conjunction with Examples 1 to 11 except that the adhesive composition comprised varying amounts of the Kraton RP-6906 thermoplastic elastomer, and a liquid hydrogenated isoprene polymer. Kuraray LIR-290 having a molecular weight of approximately 25,000 as a liquid rubber component. In addition, the adhesive compositions of Examples 31 and 32 were prepared in a 0.47 1 (1 pint) glass jar. The pellet processing tape of Example 32 also included a preparation layer, the composition of which is described below in conjunction with Example 37. Additional information about the adhesive compositions of these examples are given in Table 5 below . Example 10 is repeated in Table 5. Also reported in Table 5 are the results of the adhesion test during the release (method A) in which the substrates were a polyimide passivating layer and an epoxy-based photoprotective layer in the company of observations. about the detachibility of the tapes.

TABLE 5 Table 5 shows that small amounts of liquid rubber may be useful in modifying the adhesion strength during release of the adhesive compositions. The amount of liquid rubber used is typically less than 20% by weight (based on the combined weight of the thermoplastic elastomer and the liquid rubber), more preferably, about 5 to less than 20% by weight. Although not specifically shown in Table 5, each example had a storage module above the Dahlquist criteria line. The tablet processing tapes of Examples 6, 10, 11, 30 and 32 were subjected to the polishing test of the semiconductor wafer described above and then their adhesion on peeling was measured (using the test procedure described in conjunction with the polishing test of the semiconductor wafer) with the results reported below in Table 6. Once the pellet processing tape was removed, the surface of the semiconductor pellet was examined according to the stain test of the pellet. semiconductor pellet described above, the results of which are also shown in Table 6, in the company of the observations about strip detachability.

TABLE 6 Examples 33 to 36 A series of processing tapes of the tablet according to the invention was prepared. The adhesive composition used in the tablet processing tape for each example was obtained by combining 20 g of a thermoplastic elastomer with 46 g of toluene in a glass jar of 0.47 1 (one pint) which was then closed and placed in a roller mill and allowed to mix until no undissolved thermoplastic elastomer is observed. At this time, the benzophenone photocrosslinking agent was added and the combination was mixed for an additional hour on the roller mill to ensure the dissolution of the benzophenone. The adhesive composition was then coated on a 50 μm thick polyethylene terephthalate film and dried using the procedure described in conjunction with examples 1 to 11. After drying, the film coated with the adhesive was passed under a bench four mercury lamps of average pressure of 200 watts / inch at a speed of 2.9 m / minute to provide a total dose of 600 mJ / cm2 to the sheet coated with the adhesive.

(The light output was measured with a light meter model UM 365 H-S from Electronic Instrumentation Technologies, Inc., Sterling VA.). Further information regarding the composition of the adhesives used in these examples is given below in Table 7 wherein the percentage of the crosslinking agent is based on the weight of the thermoplastic elastomer. The adhesives described in examples 5 and 12 were made again and retested as shown in Table 7. Also shown in Table 7 are the results of the peel adhesion test (method A) on various substrates ( a passive layer of polyimide IC and an epoxy-based photoprotective layer) in the company of the observations about the detachability of the tape.

TABLE 7 * "min." means minutes Table 7 shows that a photoprotection agent can be used to reduce the adhesion in the release of the non-hydrogenated thermoplastic elastomer, especially the thermoplastic elastomers SIS and SBS. However, increasing amounts of the photocrosslinking agent can lead to a residue of the adhesive on the bonded surface after the removal of the tablet processing tape. The amount of the photo-crosslinking agent is typically in the form of about 0.05 to 2% by weight of the thermoplastic elastomer, more preferably in about 0.2 to 1% by weight, and more preferably in about 0.3 to 0.5% by weight form. Although not specifically shown in Table 7, each of the thermoplastic elastomers of the example had a storage modulus above the Dahlquist line of the criteria. A . Additional series of three tablet processing tapes according to the invention were then prepared. These tapes used the adhesive composition of Example 18 (a SEPS thermoplastic elastomer) to which 0%, 0.5% and 1.0% benzophenone photocrosslinking agent (based on the weight of the thermoplastic elastomer) was added. The adhesive composition with the photocrosslinker was then coated on a polyethylene terephthalate film 50 μm thick to a dry thickness of approximately 85 μm and dried following the procedure described in conjunction with examples 1 to 11. After drying , the film coated with the adhesive was passed six times under an average pressure mercury lamp of 7.87 Watts / mm (220 Watts / inch) at a speed of 24 m / min to provide a total dose of 600 mJ / cm2 at the sheet coated with the adhesive. (The light output was measured with a light meter Model UM 365 H-S as above). The second series of pellet processing tapes was then evaluated for adhesion on peel (using test method A) and a drying time of 16 hours on a TC polyimide substrate. (The IC polyimide substrate was representative of those used in the semiconductor wafer fabrication industry but with a different polyimide and electronic circuit configuration than that used in the other examples). Adhesion in the detachment of the sample that does not contain the benzophenone was 6.69 kgmw (170 gliw), the adhesion in the detachment of the sample containing 0.5% of benzophenone was 4.65 kglmw (118 gliw), and the adhesion in the detachment of the sample containing 1.0% of the benzophenone was 1.46 kglmw (37 gliw). All three samples were detachable. The storage module of the thermoplastic elastomer used in these examples was above the Dahlquist criteria line. The second series of examples showed that a crosslinking agent can be employed in a useful manner to reduce adhesion in the release of the adhesive compositions comprising the hydrogenated thermoplastic elastomers, especially those which are based on styrene-ethylene / propylene-styrene.

Example 37 A 3.85 kg Kraton RP-6906 thermoplastic elastomer and 7.15 kg toluene were added to a closed lid 18.92 1 (five gallons) bucket. The closed cube was then placed on two rollers of large mills and the mixture was allowed to mix until nothing was observed of the undissolved thermoplastic elastomer (approximately 16 hours). The solution of the thermoplastic elastomer was then diluted to a concentration of 25% solids using a dilution solvent comprised of 50/25/25% w / w / w of toluene / methyl ethyl ketone / isopropanol. Using a positive displacement pump, the thermoplastic elastomer solution was coated on a grooved die or die to a thickness of 84 μm on a 50 μm thick polyethylene terephthalate backing. The backing has been previously coated with a 5 μm thick (dry thickness) coating layer that comprised 10% solids of the polymer / solvent solution in which the solvent consisted of a 65% toluene / methyl ethyl ketone mixture. 35% w / w and the polymer consisted of a mixture of equal parts of polychloroprene rubber, calcium and zinc resonate, terpene resin and equal parts of a polymer of acrylonitrile-butadiene and a phenolic resin, the combined parts of the last two materials is equal to approximately 60% of the total polymer weight. The preparation and thermoplastic elastomer solutions were separately dried by passing the wet coated film through a four-zone forced air drying oven, with zones one and two set at approximately 65 ° C, zone three adjusted to approximately 80 ° C, and zone four adjusted to approximately 93 ° C, and line speeds of approximately 7.6 and 3 meters / minute, respectively. During the exit from the furnace, a silicone-coated polyethylene terephthalate release liner was laminated onto the dry adhesive surface and the structure was rolled up on itself.

The rolled items were then converted to a clean place of class 1000 in individual rolls using a Dusenberry shear router. Example 37 was then evaluated using the polishing test of the semiconductor wafer with a passive polyimide layer of IC and an epoxy-based photoprotective layer as the substrates. The adhesion in the release was measured as described in the polishing test of the semiconductor wafer. The results are shown below in Table 8 in the company of observations about the condition of the substrate surface after the removal of the pellet processing tape. Also shown in Table 8 are three commercially available tablet processing tapes, which. they are widely used in the manufacture of semiconductor wafers. In general commercially available tapes include an ethylene / vinyl acetate copolymer backing (approximately 125 to 150 μm thick) with an acrylic adhesive layer (thickness less than 25 μm) on the backing.

TABLE 8 Table 8 shows the superior performance of the tablet processing tapes of the invention when compared to three widely used commercially available tapes. The tablet processing tapes of the invention showed only an occasional trace amount of dyeing over the IC polyimide while commercially available tapes showed higher levels of dyeing. On the photoprotective layer, the tablet processing tape of example 37 showed no dyeing or damage; the commercially available tapes both fractured and stained. Although not shown specifically in Table 8, Example 37 had a storage module above the Dahlquist criteria line.

Examples 38 to 43 A series of processing tapes of the tablet according to the invention were prepared. In each example, the adhesive composition was obtained by preparing a solvent solution of the thermoplastic elastomer which comprised 24% by weight of the thermoplastic elastomer, 69% by weight of toluene, and 7% by weight of isopropanol. These ingredients were combined in a 3,785 1 (1 gallon) metal can and then mixed in a roller mill for 24 hours until there was no visible evidence of undissolved thermoplastic elastomer. The adhesive composition was then coated on the polyethylene terephthalate backing which has been prepared as described in conjunction with Example 37. The adhesive coating was carried out at a rate of 1.52 m (5 feet) per minute using a box of knives 22.86 cm (9 inches) wide with a break-off blade that was adjusted to provide a dry adhesive thickness of approximately 50 μm. The film coated with the adhesive was then dried. The thermoplastic elastomer and the thickness of the backing were varied as shown in Table 9 below.

TABLE 9 The tensile strength and elongation properties of several of the examples were then tested as described above and with the results reported later in Table 10. The Nitto Denko V-12-S is also shown later in Table 10. which is a widely used, commercially available chip fragmentation tape, which includes a vinyl backing approximately 110 μm thick and an acrylic pressure sensitive adhesive approximately 10 μm thick.

TABLE 10 Table 10 shows that the tablet processing tapes of the invention have a higher transverse direction tensile strength and a lower elongation (in both directions) than commercially available tape. Permanent backings that have low tensile strength or high elongation will stretch further when placed in contact with a semiconductor IC chip removal probe than permanent backs with higher tensile strength or longer elongation short. The backs that stretch further can lead to slower manufacturing speed since the distance the probe travels will be increased. In addition, when the rigidity of the permanent backing is increased (i.e., high tensile strength, short elongation) it is easier to manipulate the larger diameter semiconductor wafers which are becoming more common. The examples were also tested to verify adhesion in the release using test method B with various substrates and drying times and with the results shown later in table 12.

Examples 44 to 49 A series of adhesive coated tapes were prepared. In each example the adhesive composition comprised a 25% solids solution of the thermoplastic elastomer which was obtained by combining 28% by weight of the thermoplastic elastomer, 64% by weight of toluene, and 8% by weight of isopropanol in a glass jar of a fourth, sealing the jar, and allowing the combination to mix on a roller table for 24 hours until there is no visible evidence of undissolved thermoplastic elastomer. The adhesive composition was then coated on a 50 μm thick polyethylene terephthalate backing using a doctor blade with a breaker tip draw bar having approximately one 100 μm thick coating void or gap. The adhesive coated film was then dried for 30 minutes at 70 ° C to give a dry adhesive thickness of about 20-30 μm. The thermoplastic elastomer was varied as shown later in Table 11.

TABLE 11 The examples were tested to verify adhesion in the release using test method B with various substrates and drying times as shown below in Table 12 in the light of the results.

TABLE 12 The above data shows the ability of the processing tapes of the tablet of the invention to incorporate relatively thin permanent backings. This can be advantageous to allow the use of a relatively thicker layer of the adhesive that can make it easier to cut the semiconductor wafers without cutting the backing. Also, with thinner backings, the amount of tape that can be wound around a core in the form of a roll can be increased, which reduces the frequency of tape roll change, thereby increasing the efficiency of the tape. the making. It could be possible to selectively increase or reduce the adhesion of these examples by the use of the adhesion modifiers as described above. Preferably, the tablet processing tapes show a minimum adhesion buildup for two weeks, and more preferably for approximately one month, so that a prolonged storage duration is provided and the need to remove the semiconductor IC chips after trimming and storing them until they are really needed is eliminated. Although not specifically shown in Table 12, each example of the invention had a storage module above the Dahlquist criteria line. Several of the examples were evaluated using the semiconductor pellet cutout test described above. The results reported later in Table 13 represent the number of complete washes of the matrix to remove the tape during the pellet trimming process.

TABLE 13 Table 13 shows that preferred examples of the invention (examples 38 and 41) gave better results than those obtained with commercially available tape. widely used. However, the tablet processing tapes of the invention were easier to work with than the commercially available tape because the tapes of the invention had a thicker layer of adhesive. Accordingly, the semiconductor wafers could be cut without cutting the backs used in the tapes of the invention. The semiconductor wafers may not be fragmented without cutting the backing of commercially available tape. If the backing of the tape is cut during the fragmentation of the pad, it could fail prematurely. In addition, even with a thick adhesive layer, the tablet processing tapes of the invention do not leave an adhesive residue on the blade of the fragmentation saw. Various modifications and alterations of this invention will become apparent to those skilled in the art without departing from the spirit and scope of the invention. It should be understood that this invention is not limited to the illustrative embodiments described herein.

It is noted that in relation to this date the best method known by the applicant to carry out the aforementioned invention, is that which is clear from the present description of the invention.

Having described the invention as above, property is claimed as contained in the following

Claims (38)

1. A semiconductor wafer processing strip, characterized in that it comprises a permanent backing and a layer of a non-pressure sensitive adhesive comprising a thermoplastic, elastomeric block copolymer on the permanent backing.

2. A semiconductor wafer processing tape according to claim 1, characterized in that the storage module of the adhesive composition at room temperature is larger than 1 x 106 Pascals,

3. A semiconductor wafer processing belt according to claim 1, characterized in that the thermoplastic elastomeric block copolymer comprises 15 to 25% by weight of styrene.

4. A semiconductor wafer processing tape according to claim 1, characterized in that the thermoplastic elastomeric block copolymer is a styrene-ethylene / propylene-styrene copolymer.

5. A semiconductor wafer processing tape according to claim 1, characterized in that the thermoplastic elastomeric block copolymer is a styrene-ethylene / propylene-styrene-ethylene / propylene block copolymer.

6. A semiconductor wafer processing tape according to claim 1, characterized in that the adhesive further comprises a sticky resin.

7. A semiconductor wafer processing tape according to claim 6, characterized in that the tackifying resin is present in an amount of less than 10% by weight, based on the combined weight of the elastomeric, thermoplastic block copolymer and the tackified resin .

8. A semiconductor wafer processing belt according to claim 7, characterized in that the tackifying resin is present in an amount of about 3 to 8% by weight, based on the combined weight of the thermoplastic elastomeric block copolymer, and of the sticky resin.

9. A semiconductor wafer processing tape according to claim 1, characterized in that the adhesive further comprises a rubber or liquid rubber.

10. A semiconductor wafer processing belt according to claim 9, characterized in that the rubber or liquid rubber is present in an amount of less than 20% by weight, based on the combined weight of the elastomeric, thermoplastic and rubber block copolymer. or liquid rubber.

11. A semiconductor wafer processing tape according to claim 10, characterized in that the liquid rubber is present in an amount of about 5% to less than 20% by weight, based on the combined weight of the elastomeric block copolymer, thermoplastic and of liquid rubber.

12. A semiconductor wafer processing belt according to claim 1, characterized in that it further comprises a preparer for bonding the adhesive to the permanent backing.

13. A semiconductor wafer processing tape according to claim 1, characterized in that it also comprises a temporary and removable protective coating on the exposed layer of the adhesive.

14. A semiconductor wafer processing tape according to claim 13, characterized in that the temporary and removable protective coating is a polyester film that does not include a release agent.

15. The use of a semiconductor wafer processing belt according to claim 1, for adhesively bonding a semiconductor wafer to the exposed layer of the adhesive.

16. A semiconductor wafer processing tape according to claim 1, characterized in that the tape exhibits a peel adhesion of about 0.79 to 19.7 kilograms per linear meter of width (20 to 500 grams per linear inch of width) to a selected substrate. from the group consisting of silicon, polyimide, a passivating layer of silicon oxynitride, and photoprotective coatings.

17. A semiconductor wafer processing tape according to claim 16, characterized in that the tape exhibits a peel adhesion of about 0.79 to 7.9 kilograms per linear meter of width (20 to 200 grams per linear inch of width) to a selected substrate. from the group consisting of silicon, an integrated circuit polyimide passivating layer, a silicon oxynitride passivator layer, and photoprotective coatings.

18. A semiconductor wafer processing tape according to claim 16, characterized in that the tape exhibits a peel adhesion of about 0.79 to 19.7 kilograms per linear meter of width (20 to 500-grams per linear inch of width) after drying in contact with the substrate for at least 7 days under environmental conditions.

19. A semiconductor wafer processing tape according to claim 17, characterized in that the tape exhibits a peel adhesion of about 0.79 to 7.9 kilograms per linear meter of width (20 to 200 grams per linear inch of width) after drying in contact with the substrate for at least 7 days under environmental conditions.

20. A semiconductor wafer processing tape, characterized in that it comprises a backing and a non-pressure sensitive adhesive layer on the permanent backing, wherein the adhesive comprises a thermoplastic, hydrogenated block copolymer, and an adhesion modifier selected from the group which consists of a sticky resin, a rubber or liquid rubber, and a photo-crosslinking agent.

21. A semiconductor wafer processing belt according to claim 20, characterized in that the adhesion modifier is a tackifying resin present in an amount of about 3 to 8% by weight, based on the combined weight of the elastomeric block copolymer, thermoplastic, hydrogenated and sticky resin.

22. A semiconductor wafer processing tape according to claim 20, characterized in that the adhesion modifier is a rubber or liquid rubber present in an amount of about 5% to less than 20% by weight, based on the combined weight of the elastomeric, thermoplastic, hydrogenated block copolymer and rubber or liquid rubber.

23. A semiconductor wafer processing tape according to claim 20, characterized in that the tape exhibits a peel adhesion of about 0.79 to 7.9 kilograms per linear meter of width (20 to 200 grams per linear inch of width) to a selected substrate. from the group consisting of silicon, an integrated circuit polyimide passivating layer, a silicon oxynitride passivator layer, and photoprotective coatings.

24. A semiconductor wafer processing tape according to claim 23, characterized in that the tape exhibits a peel adhesion of about 0.79 to 7.9 kilograms per linear meter of width (20 to 200 grams per linear inch of width) after drying in contact with the substrate for at least 7 days under environmental conditions.

25. A semiconductor wafer processing tape, characterized in that it comprises a permanent backing and a non-pressure sensitive adhesive layer on the permanent backing, wherein the adhesive comprises an elastomeric, thermoplastic block copolymer and a photocrosslinking agent.

26. A semiconductor wafer processing tape according to claim 25, characterized in that the tape exhibits a peel adhesion of about 0.79 to 7.9 kilograms per linear meter of width (20 to 200 grams per linear inch of width) to a selected substrate. from the group consisting of silicon, an integrated circuit polyimide passivating layer, a silicon oxynitride passivator layer, and photoprotective coatings.

27. A semiconductor wafer processing tape according to claim 26, characterized in that the tape exhibits a peel adhesion of about 0.79 to 7.9 kilograms per linear meter of width (20 to 200 grams per linear inch of width) after drying in contact with the substrate for at least 7 days under environmental conditions.

28. A semiconductor wafer processing tape, characterized in that it comprises a permanent backing and a non-pressure sensitive adhesive layer on the permanent backing, wherein the adhesive comprises a thermoplastic, hydrogenated elastomeric block copolymer, exhibiting a module in the storage at 20 ° C from 2.7 x 106 to 4.0 x 106 Pascals.

29. A semiconductor wafer processing ribbon according to claim 28, characterized in that the thermoplastic, hydrogenated, elastomeric block copolymer is a styrene-ethylene / propylene-styrene block copolymer.

30. A semiconductor wafer processing tape according to claim 28, characterized in that the thermoplastic, hydrogenated elastomeric block copolymer is a styrene-ethylene / propylene-styrene-ethylene / propylene block copolymer.

31. A semiconductor wafer processing tape, characterized in that it comprises a permanent backing and a layer of non-pressure sensitive adhesive on the permanent backing, wherein the adhesive has a storage module at room temperature greater than 1 x 106 Pascals and comprises an elastomeric block copolymer, thermoplastic and further wherein the tape exhibits a peel adhesion of about 0.79 to 19. 7 kilograms per linear meter of width (20 to 500 grams per linear inch of width) to a substrate selected from the group consisting of silicon, polyimide, a silicon oxynitride psoriasis layer, and photoprotective coatings both at the time of application of the tape as after drying in contact with the substrate for at least 7 days under ambient conditions.

32. A semiconductor wafer processing tape according to claim 31, characterized in that it further comprises an adhesion modifier selected from the group consisting of a sticky resin, liquid rubber and photocrosslinking agent.

33. A semiconductor wafer processing belt according to claim 31, characterized in that the elastomeric, thermoplastic block copolymer comprises blocks of styrene and ethylene / propylene.

34. A fragmentation strip of semiconductor wafers, characterized in that it comprises a permanent backing and a layer of a non-pressure sensitive adhesive on the permanent backing, wherein the adhesive has a module in storage at an ambient temperature greater than 1 x 106 Pascals and it comprises an elastomeric, thermoplastic block copolymer, and furthermore wherein the tape exhibits a peel adhesion of about 0.79 to 7.9 kilograms per linear meter of width (20 to 200 grams per linear inch of width) to the silicon surface of a semiconductor wafer both at the time of application of the tape and after drying in contact with the substrate for at least 7 days under ambient conditions.

36. A fragmentation strip of semiconductor wafers according to claim 34, characterized in that the adhesion on peeling at the time of application of the tape to the substrate and after drying in contact with the substrate for at least 15 days under ambient conditions is from about 0.79 to 7.9 kilograms per linear meter of width (20 to 200 grams per linear inch of width).

36. A fragmentation ribbon of semiconductor wafers according to claim 26, characterized in that the permanent backing has a thickness of about 12 to 25 μm.

37. A fragmentation strip of semiconductor wafers according to claim 26, characterized in that the permanent backing has an elongation at the break of approximately 120 to 165% in the machine direction

38. A method of processing semiconductor wafers, the method is characterized in that it comprises the steps of: (a) providing a semiconductor wafer; (b) adhesively bonding the semiconductor wafer to the adhesive surface of a semiconductor wafer processing strip comprising a permanent backing and a layer of a non-pressure sensitive adhesive on the permanent backing, the adhesive comprises an elastomeric block copolymer , thermoplastic; and (c) processing the semiconductor chips either by polishing the back side of the chips or by fragmenting the chips into integrated circuit semiconductor chips.