Dicing sheet for plasma dicing, method for producing semiconductor chip, and method for producing semiconductor package

Abstract

Provided are: a dicing sheet for plasma dicing, the dicing sheet having a base material that satisfies (a)-(c) below and a pressure-sensitive adhesive agent layer that is arranged on one surface of the base material; and a method for producing a semiconductor chip or a semiconductor package, the method using the dicing sheet for plasma dicing. (a) The content of a thermoplastic elastomer is 5-50 mass %; (b) the main melting peak temperature in a differential scanning calorimetry analysis is 105 °C or more; and (c) the thickness is 60-300 um.

Description

Dicing sheet for plasma dicing, method for manufacturing semiconductor chips, and method for manufacturing semiconductor packages

[0001] This invention relates to a dicing sheet for plasma dicing, a method for manufacturing a semiconductor chip, and a method for manufacturing a semiconductor package.

[0002] When obtaining semiconductor chips by dicing (dividing) a semiconductor wafer, a dicing sheet (dicing tape, dicing film) is bonded to the back surface (grinding surface) of the semiconductor wafer, and this dicing sheet is fixed to a dicing frame, on which the semiconductor wafer is diced. Therefore, the dicing sheet is required to have properties that allow it to fix the semiconductor wafer with sufficient adhesive force during dicing, while expanding after dicing to increase the distance between semiconductor chips, allowing the semiconductor chips to be easily picked up from the dicing sheet. To achieve these properties, a dicing sheet has been put into practical use that is made by laminating a substrate with desired expandability and an energy-ray curable adhesive layer. The energy-ray curable adhesive layer firmly fixes the semiconductor wafer with high adhesive force during dicing, while after dicing, the adhesive layer hardens by irradiation with energy rays such as ultraviolet light, reducing the adhesive force. As a result, good pickability can be achieved while maintaining the good expandability of the substrate.

[0003] A widely used method for dicing semiconductor wafers is to mechanically cut the wafer using a dicing blade (rotating blade). However, this method is prone to causing defects (chipping) in the semiconductor chips due to vibrations caused by the dicing blade, which can lead to contact between the semiconductor chips and the dicing blade, or between the semiconductor chips themselves. To address this problem, several dicing methods that do not use a dicing blade have been proposed, one of which is plasma dicing. Plasma dicing is a method of dividing a semiconductor wafer by selectively etching areas not covered by a mask with plasma. Plasma dicing is considered one of the optimal dicing processes due to its extremely high etching rate.

[0004] In plasma dicing, sulfur hexafluoride (SF ６ ) and carbon tetrafluoroethylene (CF ４ ) uses fluorine-based gases, which have very high reactivity with semiconductor wafers, as plasma generation gases, and therefore have excellent etching rates. However, because the processing is performed at high temperatures (for example, around 110°C) by plasma, the dicing sheet used requires special properties. That is, it must have both heat resistance that prevents melting at high temperatures and sufficient expandability (heat-resistant expandability) after exposure to high temperatures. The properties of the resin constituting the substrate are dominant in the expression of these properties, but generally, resins with high heat resistance tend to have poor flexibility, and resins with high flexibility tend to have poor heat resistance, making it difficult to create a substrate that achieves both high levels of heat resistance and flexibility. As a technology that focuses on this problem, for example, Patent Document 1 describes the following wafer fixing tape.

[0005] A wafer fixing tape comprising a base film and an adhesive layer, wherein the base film contains an ionomer resin obtained by crosslinking a ternary copolymer with metal ions, and the arithmetic mean roughness Ra of the surface of the base film opposite to the adhesive layer is 0.1 to 3.0 μm.

[0006] According to the wafer fixing tape described in Patent Document 1 above, it has heat resistance during plasma dicing and good pick-up properties, which can reduce the occurrence of chipping and improve yield.

[0007] Japanese Patent Publication No. 2016-171261

[0008] A dicing die bonding sheet, which integrates a dicing sheet and a die bonding sheet, is known. In a dicing die bonding sheet, the semiconductor wafer and the die bonding sheet are cut together by dicing, and in the pickup process, the semiconductor chip is picked up together with the cut die bonding sheet piece, and the semiconductor chip is mounted onto a substrate such as a lead frame via this die bonding sheet piece. When such a dicing die bonding sheet is applied to plasma dicing, it is necessary to cut not only the wafer but also the die bonding sheet, resulting in longer processing times compared to using a dicing sheet alone, and a tendency to require higher heat resistance. Furthermore, in plasma dicing, semiconductor wafers are often fragmented into tiny chip sizes of 1 mm or less. Therefore, in order to ensure sufficient spacing between all semiconductor chips in the pickup process, the expandability requirements of the dicing sheet are also becoming more sophisticated. In this invention, the term "dicing sheet" is used to encompass both a dicing sheet alone (a sheet consisting of a laminate of a base material and an adhesive layer) and a dicing die bonding sheet (a sheet consisting of a laminate of a base material, an adhesive layer, and a bonding agent layer), unless otherwise specified.

[0009] The present invention aims to provide a dicing sheet for plasma dicing that has excellent heat resistance and excellent expandability after exposure to high temperatures. The present invention also aims to provide a method for manufacturing a semiconductor chip or semiconductor package using the dicing sheet for plasma dicing.

[0010] The above problems of the present invention are solved by the following means: [1] A dicing sheet for plasma dicing having a substrate that satisfies the following (a) to (c) and an adhesive layer disposed on one side of the substrate: (a) Thermoplastic elastomer content is 5 to 50% by mass; (b) Main melting peak temperature in differential scanning calorimetry is 105°C or higher; (c) Thickness is 60 to 300 μm. [2] The dicing sheet for plasma dicing according to [1], wherein the substrate contains a polyolefin resin. [3] The dicing sheet for plasma dicing according to [2], wherein the polyolefin resin contains polypropylene. [4] The dicing sheet for plasma dicing according to any one of [1] to [3], wherein the thermoplastic elastomer contains a styrene-based thermoplastic elastomer. [5] The dicing sheet for plasma dicing according to [3], wherein the thickness of the substrate is less than 100 μm. [6] A dicing sheet for plasma dicing according to any one of [1] to [5], wherein the thickness of the substrate is less than 85 μm. [7] A dicing sheet for plasma dicing according to any one of [1] to [5], wherein the thickness of the substrate is greater than 85 μm. [8] A dicing sheet for plasma dicing according to any one of [1] to [7], wherein the adhesive layer is energy ray curable. [9] A dicing sheet for plasma dicing according to any one of [1] to [8], wherein the adhesive layer is on the side of the adhesive layer opposite to the substrate side.

[10] A method for manufacturing a semiconductor chip, comprising fixing a semiconductor wafer via a dicing sheet for plasma dicing according to any one of [1] to [9], and obtaining a semiconductor chip on the dicing sheet for plasma dicing by plasma dicing.

[11] A method for manufacturing a semiconductor package, comprising picking up the semiconductor chip obtained by the manufacturing method described in

[10] from the dicing sheet for plasma dicing and mounting it on a wiring board.

[0011] In this invention, a numerical range represented using "~" means a range that includes the numbers written before and after "~" as the lower and upper limits, respectively.

[0012] The dicing sheet for plasma dicing of the present invention has excellent heat resistance and also excellent expandability after exposure to high temperatures. The semiconductor chip or semiconductor package manufacturing method of the present invention makes it possible to manufacture semiconductor chips or semiconductor packages with a higher yield while applying plasma dicing to the process of dicing semiconductor wafers.

[0013] Figure 1 is a schematic cross-sectional view illustrating the process up to the application of surface protection tape to a semiconductor wafer when performing a plasma dicing process. Figure 1(a) shows the semiconductor wafer, Figure 1(b) shows the application of surface protection tape, and Figure 1(c) shows the semiconductor wafer with the surface protection tape applied. Figure 2 is a schematic cross-sectional view illustrating the process up to the thinning of a semiconductor wafer and the formation of a mask when performing a plasma dicing process. Figure 2(a) shows the thinning process of the semiconductor wafer, Figure 2(b) shows the peeling of the surface protection tape, Figure 2(c) shows the state with a mask formed on the pattern surface, and Figure 2(d) shows one form of layer configuration of the dicing sheet of the present invention. Figure 3 is a schematic cross-sectional view illustrating the process from plasma dicing to the individualization of a semiconductor wafer into semiconductor chips. Figure 3(a) shows a thin-film semiconductor wafer with a mask formed on its patterned surface to which the dicing sheet of the present invention has been bonded. Figure 3(b) shows the plasma dicing process. Figure 3(c) shows the thin-film semiconductor wafer being fragmented into semiconductor chips by plasma dicing. This is a schematic cross-sectional view illustrating the process from plasma dicing to picking up the semiconductor chips. Figure 4(a) shows the plasma ashing process. Figure 4(b) shows the state after the mask (resist) has been removed. Figure 4(c) shows the chip being picked up.

[0014] [Dicing Sheet for Plasma Dicing] The dicing sheet for plasma dicing of the present invention (hereinafter also simply referred to as "the sheet of the present invention") comprises a base material (base material film) and an adhesive layer disposed on one side of the base material. The sheet of the present invention may have an adhesive layer on the side of the adhesive layer opposite to the base material side. The sheet of the present invention in this form can be used as a dicing die bonding sheet for plasma dicing. The sheet of the present invention is characterized by the composition of the base material compared to conventional products. That is, in the sheet of the present invention, the base material satisfies all of the following requirements (a) to (c): (a) Thermoplastic elastomer content is 5 to 50% by mass; (b) Main melting peak temperature in differential scanning calorimetry is 105°C or higher; (c) Thickness is 60 to 300 μm. The heat resistance and flexibility of the dicing sheet are dominated by the properties of the base material, and in the present invention, by having the base material satisfy the above requirements (a) to (c), sufficient heat resistance can be imparted to the resulting sheet, and the expandability after exposure to high temperatures can also be further improved. As a result, a dicing sheet suitable for plasma dicing applications can be provided.

[0015] The sheet of the present invention can be adapted to the purpose by appropriately adopting conventional configurations applicable to plasma dicing, or by adjusting the design as necessary, for components other than the base material (such as adhesive layers and bonding layers). Furthermore, the plasma dicing conditions (including the plasma dicing conditions themselves, as well as the formation and removal of masks described later) can also be adapted to the purpose by appropriately adopting conventional conditions, or by adjusting the design as necessary. For components other than the base material and plasma dicing conditions, for example, the descriptions in Japanese Patent Publication No. 2016-171261 and Japanese Patent Publication No. 2022-97290 can be appropriately referred to.

[0016] <Substrate> (Requirement (a) above) The sheet of the present invention has a substrate containing a thermoplastic elastomer, the content of which is 5 to 50% by mass. By controlling the content of the thermoplastic elastomer within the range of 5 to 50% by mass while the substrate contains a resin that leads to requirement (b) above, flexibility is imparted to the substrate, and excellent heat resistance that can withstand plasma dicing can also be achieved.

[0017] The above-mentioned thermoplastic elastomer is not particularly limited, and a wide range of styrene-based thermoplastic elastomers, olefin-based thermoplastic elastomers, urethane-based thermoplastic elastomers, ester-based thermoplastic elastomers, polyamide-based thermoplastic elastomers, etc., can be used.

[0018] - Styrene-based thermoplastic elastomers - Examples of styrene-based thermoplastic elastomers include styrene-butadiene block copolymer (SBR), hydrogenated styrene-butadiene block copolymer (SEB, styrene-ethylene / butylene block copolymer), styrene-butadiene-styrene block copolymer (SBS), hydrogenated styrene-butadiene-styrene block copolymer (SEBS, styrene-ethylene / butylene-styrene block copolymer), styrene-isoprene block copolymer (SIR), hydrogenated styrene-isoprene block copolymer (SEP, styrene-ethylene / propylene block copolymer), styrene-isoprene-styrene block copolymer (SIS), hydrogenated styrene-isoprene-styrene block copolymer (SEPS, styrene-ethylene / propylene-styrene block copolymer), and the like. The above substrate may contain one or more of these styrene-based thermoplastic elastomers.

[0019] - Olefin-based thermoplastic elastomers - Examples of olefin-based elastomers include ethylene-propylene copolymer, ethylene-1-butene copolymer, ethylene-α-olefin copolymer, propylene-1-butene copolymer, propylene-α-olefin copolymer, 1-butene-α-olefin copolymer, propylene-1-butene-ethylene copolymer, propylene-α-olefin-ethylene copolymer, propylene-α-olefin-1-butene copolymer, and 1-butene-α-olefin-ethylene copolymer. The above substrate may contain one or more of these olefin-based thermoplastic elastomers.

[0020] - Urethane-based thermoplastic elastomers - Examples of urethane-based thermoplastic elastomers include elastomers containing structural units of a hard segment consisting of low molecular weight glycol and diisocyanate, and a soft segment consisting of high molecular weight (long-chain) diol and diisocyanate. Examples of high molecular weight (long-chain) diols include polypropylene glycol, polytetramethylene oxide, poly(1,4-butylene adipate), poly(ethylene-1,4-butylene adipate), polycaprolactone, poly(1,6-hexylene carbonate), and poly(1,6-hexylene-neopentylene adipate). The number average molecular weight of the high molecular weight (long-chain) diol is preferably 500 or more and less than 10,000. As low molecular weight glycols, short-chain diols such as ethylene glycol, propylene glycol, 1,4-butanediol, and bisphenol A can be used. The number average molecular weight of the short-chain diol is preferably 48 or more and less than 500. The above-mentioned substrate may contain one or more of these urethane-based thermoplastic elastomers.

[0021] - Polyamide-based thermoplastic elastomers - Examples of polyamide-based thermoplastic elastomers include multiblock copolymers in which the hard segment is polyamide and the soft segment is polyether or polyester. Examples of hard segments include polyamide 6, 66, 610, 11, 12, etc. Examples of polyethers in the soft segment include polyethylene glycol, diol poly(oxytetramethylene) glycol, poly(oxypropylene) glycol, etc., and examples of polyesters include poly(ethylene adipate) glycol, poly(butylene-1,4-adipate) glycol, etc. The above substrate may contain one or more of these polyamide-based thermoplastic elastomers.

[0022] - Ester-based thermoplastic elastomer - As the ester-based thermoplastic elastomer, for example, a block copolymer consisting of a high-melting-point polyester segment (hard segment) and a low-melting-point polymer segment (soft segment) with a molecular weight of about 400 to 6000 can be used. As the high-melting-point polyester segment, for example, polybutylene terephthalate (PBT) can be used. As the low-melting-point polymer segment, for example, an amorphous polyether with a glass transition temperature of -70°C, such as polytetramethylene ether glycol (PTMG) can be used. The above substrate may contain one or more of these ester-based thermoplastic elastomers.

[0023] In particular, the above-mentioned base material preferably contains a styrene-based thermoplastic elastomer. The proportion of styrene-based thermoplastic elastomer in the total thermoplastic elastomer contained in the above-mentioned base material is preferably 50% by mass or more, more preferably 60% by mass or more, even more preferably 70% by mass or more, even more preferably 80% by mass or more, and even more preferably 90% by mass or more. It is also preferable that all of the thermoplastic elastomer contained in the above-mentioned base material is a styrene-based thermoplastic elastomer.

[0024] The content of thermoplastic elastomer in the above-mentioned substrate is preferably 10 to 50% by mass, more preferably 15 to 50% by mass, and also preferably 20 to 45% by mass.

[0025] (Requirement (b)) The sheet of the present invention has a main melting peak temperature of 105°C or higher, obtained by subjecting the substrate to differential scanning calorimetry (DSC analysis). By having the substrate contain a specific amount of the thermoplastic elastomer and the remainder contain a resin exhibiting a relatively high melting point that leads to requirement (b), both the flexibility and heat resistance of the substrate can be increased to a desired level suitable for use as a dicing sheet for plasma dicing. In the present invention, "main melting peak temperature" means the temperature of the peak with the highest peak height among the melting peaks (endothermic peaks) observed in DSC analysis. Since the melting peak in DSC analysis is a downward-pointing peak, the "peak with the highest peak height" means the "peak with the largest downward drop" when considering the direction of the peak. The "main melting peak" is usually a peak derived from the resin contained in the substrate (the resin contained in the remainder after removing the thermoplastic elastomer and constituting the main component of the substrate). The main melting peak temperature determined by the above DSC analysis can be determined in accordance with JIS K7121 (2012). More specifically, the melting peak can be determined based on the observed melting peak when the substrate sample to be measured is cut into 10 mg portions, placed in a measuring container (aluminum pan), and heated from 30°C to 250°C at a heating rate of 10°C / min using DSC.

[0026] The main melting peak temperature of the above-mentioned substrate is preferably 105 to 200°C, more preferably 105 to 180°C, even more preferably 105 to 160°C, and still more preferably 105 to 140°C.

[0027] (Requirement (c)) The sheet of the present invention has a substrate thickness of 60 to 300 μm. The substrate thickness is preferably 60 to 200 μm, more preferably 60 to 150 μm, even more preferably 60 to 120 μm, and even more preferably 60 to 100 μm. This thickness may be 60 μm or more and less than 100 μm, and is also preferably 65 to 98 μm, and also preferably 70 to 96 μm. When the substrate thickness is thick, the expandability tends to decrease, and by setting the substrate thickness to, for example, less than 100 μm, the expandability can be increased more stably and sufficiently. Also, if the substrate thickness is too thin, breakage is likely to occur during expansion, and it tends to be difficult to ensure uniform expandability.

[0028] From the viewpoint of more easily transmitting pin-pushing stress to the chip during pickup, the thickness of the base material is preferably 60 μm or more and less than 85 μm, more preferably 65 to 84 μm, and even more preferably 70 to 83 μm.

[0029] From the viewpoint of further reducing the risk of substrate breakage during expansion, the thickness of the substrate is preferably greater than 85 μm and less than 100 μm, more preferably between 86 and 98 μm, and even more preferably between 87 and 96 μm or less.

[0030] The above-mentioned substrate typically contains a resin in the remainder after removing the thermoplastic elastomer. The melting point of this resin is typically 105°C or higher, preferably 110 to 200°C, more preferably 120 to 200°C, even more preferably 130 to 200°C, even more preferably 140 to 190°C, and even more preferably 150 to 180°C. The above-mentioned resin is preferably a polyolefin resin. Specific examples of polyolefin resins include polypropylene, polyethylene, ethylene-propylene copolymer, ethylene-acrylic acid copolymer, ionomer, polybutene-1, poly-4-methylpentene-1, ethylene-vinyl acetate copolymer, ethylene-methyl acrylate copolymer, and ethylene-acrylic acid copolymer. In this invention, as is commonly understood in the art to which this invention belongs, resins and elastomers are positioned as different entities. Some thermoplastic elastomers contain propylene components, but polymers that fall under the category of thermoplastic elastomers do not fall under the category of resins. The resin content in the above-mentioned substrate is preferably 50 to 90% by mass, more preferably 50 to 85% by mass, and also preferably 55 to 80% by mass.

[0031] The above-mentioned base material preferably has a tensile modulus of 10 to 50 MPa, more preferably 20 to 45 MPa, even more preferably 23 to 40 MPa, even more preferably 25 to 35 MPa, and even more preferably 25 to 30 MPa. By controlling the tensile modulus of the base material within the above range, it becomes less likely to break during expansion, and the pin-pushing stress can be sufficiently transmitted to the tip during pickup. The tensile modulus can be determined in accordance with JIS K6251 (2017). More specifically, a test specimen was prepared by punching out a No. 1 dumbbell shape, and the tensile modulus was determined by measuring the load at break between the gauge marks under the conditions of a gauge mark distance of 40 mm, 23°C, and a tensile speed of 300 mm / min.

[0032] <Adhesive Layer> The adhesive layer of the sheet of the present invention must possess both heat resistance that allows it to maintain its adhesive strength even after plasma dicing or plasma ashing, and easy peelability when picking up semiconductor chips after dicing. Such adhesive layers themselves are well known, and for example, it is known to use non-curing adhesive layers (pressure-sensitive adhesive layers) or energy-ray curing adhesives. The sheet of the present invention can be fitted with any of these adhesive layers, but it is preferable to have an energy-ray curing adhesive layer. The energy-ray curing adhesive layer undergoes a curing reaction (three-dimensional networking) by irradiating it with energy rays (ultraviolet rays, electron beams, etc.) after plasma dicing and before the picking process, which reduces its adhesive strength, making it easier to pick up semiconductor chips, and also reduces the amount of adhesive residue left on the surface of the picked-up semiconductor chips. As described above, the adhesive layer constituting the sheet of the present invention can be a conventional adhesive layer applicable to plasma dicing, which can be appropriately adopted depending on the purpose, or the design can be adjusted as necessary. For example, the structure of the adhesive layer described in Japanese Patent Publication No. 2016-171261 is suitable as the adhesive layer of the sheet of the present invention. From the viewpoint of further suppressing adhesive residue in the pick-up process, it is preferable that the above adhesive layer does not contain components that are prone to bleeding out (for example, low molecular weight components, mold release agent components, etc.; specifically, silicone compounds, etc.).

[0033] <Adhesive Layer> In addition to the laminated structure of a substrate and an adhesive, the sheet of the present invention may also have an adhesive layer on the side of the adhesive layer opposite to the substrate side. In this case, the sheet of the present invention can be used as a dicing die bonding sheet for plasma dicing (also referred to as "dicing die bonding tape," "dicing die attach film," etc.). By providing an adhesive layer on the adhesive layer to make it a dicing die bonding sheet, it becomes easier to proceed to the die bonding process after picking up the semiconductor chip. When the sheet of the present invention is a dicing die bonding sheet, the structure of the adhesive layer itself is known, and a normal adhesive layer applicable to plasma dicing can be appropriately adopted depending on the purpose, or the design can be adjusted as necessary. For example, a curable composition containing epoxy resin, a curing agent, a binder resin (phenoxy resin, acrylic resin, polyurethane resin, etc.), a thermally conductive filler, etc. is suitable as an adhesive layer that can be used in the sheet of the present invention. Details of the adhesive layer that can be used in the sheet of the present invention can be found in, for example, International Publication No. 2012 / 160916, International Publication No. 2021 / 033368, Japanese Patent No. 7042986, and the like.

[0034] <Plasma Dicing> Plasma dicing methods themselves are well known, and conventional methods can be appropriately adopted depending on the purpose, or the design can be adjusted as necessary.

[0035] An example of plasma dicing will be explained with reference to the drawings. A semiconductor wafer 1 has a patterned surface 2 on its surface S where circuits of semiconductor elements are formed (see Figure 1(a)). A surface protection tape 3 is bonded to this patterned surface 2 (see Figure 1(b)), and a semiconductor wafer 1 is obtained in which the patterned surface 2 is covered with the surface protection tape 3 (see Figure 1(c)).

[0036] Next, the back surface B of the semiconductor wafer 1 is ground by a wafer grinding apparatus M1 to reduce the thickness of the semiconductor wafer 1 (see FIG. 2(a)). Thereafter, the surface protection tape 3 is peeled off from the patterned surface 2 (see FIG. 2(b)). A resist 4 is laminated on the exposed patterned surface 2 in accordance with a common method to form a mask (see FIG. 2(c)). Meanwhile, the sheet 5 of the present invention to be attached to the back surface of the wafer is prepared. Here, as the sheet 5 of the present invention, one having a two-layer structure in which an adhesive layer 5b is laminated on a base film 5a is shown (see FIG. 2(d)).

[0037] The sheet 5 of the present invention is attached to the ground back surface B of the semiconductor wafer 1, and is supported and fixed to a ring frame F (see FIG. 3(a)). Then, from the front surface S side, SF ６ processing is performed using gas plasma P1, the semiconductor wafer 1 is etched (see FIG. 3(b)), and divided into individual semiconductor chips (hereinafter, also simply referred to as "chips") 7 to be singulated (see FIG. 3(c)).

[0038] Next, O ２ ashing is performed using gas plasma P2 (see FIG. 4(a)), the resist 4 remaining on the front surface S is removed, and the patterned surface 2 is exposed on the surface to obtain singulated chips 7 (see FIG. 4(b)). Then, the chips 7 are pushed up by pins M2, adsorbed by a collet M3, and picked up (see FIG. 4(c)).

[0039] Note that SF ６ plasma and O ２ the etching rate by plasma is preferably 2.0 µm / min or less, more preferably 1.0 µm / min or less, and still more preferably 0.5 µm / min or less. The lower limit of the etching rate is preferably 0.1 µm / min or more.

[0040] Next, the materials used in the above examples will be described. The semiconductor wafer 1 is, for example, a silicon wafer having a patterned surface 2 on one side where circuits of semiconductor elements and the like are formed, and the patterned surface 2 is the surface where circuits of semiconductor elements and the like are formed.

[0041] The surface protection tape 3 has a function of protecting semiconductor elements formed on the pattern surface 2. That is, in the subsequent wafer thinning step, the semiconductor wafer 1 is supported by the pattern surface 2 and the back surface of the wafer is ground, so it is necessary to withstand the load during this grinding. Therefore, the surface protection tape 3 has a thickness sufficient to cover the elements formed on the pattern surface 2, has low pressing resistance, and has high adhesiveness enough to allow the elements to be closely adhered so as to prevent intrusion of dust, grinding water and the like during grinding. The surface protection tape 3 itself is widely known to those skilled in the art, and a conventional surface protection tape can be used.

[0042] A general resist such as those used in photolithography processes can be applied as the resist 4. In addition, a conventional spin coating method or the like can be used for the coating step on the pattern surface 2.

[0043] A plasma etching apparatus can be used to perform plasma dicing and plasma ashing. The plasma etching apparatus is an apparatus capable of performing dry etching on the semiconductor wafer 1, in which a sealed processing space is formed in a vacuum chamber, the semiconductor wafer 1 is placed on an electrostatic chuck table on a high-frequency electrode side, and a plasma generating gas is supplied from a gas supply electrode side provided opposite to the high-frequency electrode. Plasma can be generated between the gas supply electrode and the high-frequency electrode by applying a high-frequency voltage to the high-frequency electrode.

[0044] In plasma dicing, the semiconductor wafer 1 in the plasma etching apparatus is fixed on the electrostatic chuck table by a fixing method called an electrostatic adsorption method, as described above.

[0045] An example of plasma dicing has been described above, the plasma dicing method itself is a known technology that has also been put into practical use. For various embodiments of plasma dicing, reference can be made to, for example, Japanese Patent Application Laid-Open No. 2016-171261, Japanese Patent Application Laid-Open No. 2014-60366, and Japanese Patent Application Laid-Open No. 2018-186240.

[0046] In relation to the plasma dicing described above, the present invention provides, in one embodiment, the following method for manufacturing a semiconductor chip: A method for manufacturing a semiconductor chip, comprising fixing a semiconductor wafer via a sheet of the present invention and obtaining a semiconductor chip on the sheet of the present invention by plasma dicing the semiconductor wafer into individual pieces.

[0047] Furthermore, in one embodiment, the present invention provides a method for manufacturing a semiconductor package, which includes picking up a semiconductor chip obtained by the above-described semiconductor chip manufacturing method from the sheet of the present invention and mounting it on a wiring board. That is, a semiconductor package can be obtained by mounting a semiconductor chip on a wiring board as described above and sealing it with a sealing resin or the like.

[0048] The present invention will be described more specifically based on examples and comparative examples, but the present invention is not limited to the embodiments described below.

[0049] [Example 1] Preparation of a dicing sheet for plasma dicing <Preparation of base film> 60 parts by mass of polypropylene and 40 parts by mass of thermoplastic elastomer (product name: Hybler, styrene-based, manufactured by Kuraray Co., Ltd.) were melt-kneaded at 205°C and formed into a long film using an extruder to obtain a base film with a thickness of 90 μm.

[0050] <Preparation of Adhesive> A copolymer of 2-ethylhexyl acrylate, 2-hydroxyethyl acrylate, and methyl methacrylate was prepared, and 2-isocyanatoethyl methacrylate was added and reacted to obtain acrylic copolymer P1. Acrylic copolymer P1 had a weight-average molecular weight of 800,000, a glass transition temperature of -64°C, an energy-ray polymerizable carbon-carbon double bond count of 23 (iodine value), and a hydroxyl value of 33.7 mgKOH / g. To 100 parts by mass of acrylic copolymer P1, 8 parts by mass of Coronate L (trade name, manufactured by Tosoh Corporation, polyisocyanate compound) was added as a curing agent, and 5 parts by mass of Irgacure 184 (trade name, manufactured by Ciba-Geigy Japan Co., Ltd.) was added as a photopolymerization initiator to obtain an energy-ray curable adhesive.

[0051] <Preparation of Adhesive> 28 parts by mass of bisphenol A type phenoxy resin (manufactured by Nippon Steel Epoxy Co., Ltd., trade name "YP-50S", Mw 60,000, Tg 84℃), 55 parts by mass of solid bisphenol A type epoxy resin (manufactured by Nippon Steel Epoxy Co., Ltd., trade name "YD-011", Mw 1,000, epoxy equivalent 450 g / eq), 49 parts by mass of liquid bisphenol A type epoxy resin (manufactured by Nippon Steel Epoxy Co., Ltd., trade name "YD-128", Mw 400, epoxy equivalent 190 g / eq), and 9 parts by mass of imidazole-based epoxy resin curing agent (manufactured by Shikoku Chemicals, Ltd., trade name "Curesol 2PHZ-PW") were dissolved in methyl ethyl ketone, and then 74 parts by mass of silica filler (manufactured by Admatex Co., Ltd., trade name "SO-C2", average particle size 0.5 μm) were mixed in to obtain an adhesive.

[0052] <Preparation of Dicing Sheet> By applying the adhesive to one side of the above-mentioned base film and drying it, a dicing sheet was obtained consisting of a laminate of a base material with a thickness of 90 μm and an adhesive layer with a thickness of 10 μm. This dicing sheet (without an adhesive layer) is one form of the sheet of the present invention.

[0053] <Preparation of adhesive film> The above adhesive was applied to a 50 μm thick polyethylene terephthalate film (release liner) that had been treated with silicone release agent, and then dried at 130°C for 5 minutes to obtain an adhesive film consisting of a laminate of a 20 μm thick adhesive layer and a release liner.

[0054] <Preparation of Dicing Die Bonding Sheet> By bonding the adhesive layer of the above adhesive film to the adhesive layer side of the above dicing sheet under the following conditions, a dicing die bonding sheet (with release liner) having a structure in which the substrate, adhesive layer, and adhesive layer are laminated in this order was obtained. This dicing die bonding sheet (with adhesive layer) is one form of the sheet of the present invention. (Bonding conditions) Pressing at a pressure of 0.3 MPa using a hand roller on a stage (70°C).

[0055] [Example 2] A dicing die bonding sheet was obtained in the same manner as in Example 1, except that the amount of polypropylene was 80 parts by mass and the amount of thermoplastic elastomer was 20 parts by mass in the preparation of the base film of Example 1.

[0056] [Example 3] A dicing die bonding sheet was obtained in the same manner as in Example 1, except that the amount of polypropylene added was 50 parts by mass and the amount of thermoplastic elastomer added was 50 parts by mass.

[0057] [Example 4] A dicing die bonding sheet was obtained in the same manner as in Example 1, except that the thickness of the base film was 60 μm in the preparation of the base film as in Example 1.

[0058] [Example 5] A dicing die bonding sheet was obtained in the same manner as in Example 1, except that the thickness of the base film was set to 100 μm in the preparation of the base film in Example 1.

[0059] [Comparative Example 1] A dicing die bonding sheet was obtained in the same manner as in Example 1, except that a base film made of polypropylene was prepared without incorporating a thermoplastic elastomer in the preparation of the base film of Example 1.

[0060] [Comparative Example 2] A dicing die bonding sheet was obtained in the same manner as in Example 1, except that the amount of polypropylene was 40 parts by mass and the amount of thermoplastic elastomer was 60 parts by mass in the preparation of the base film of Example 1.

[0061] [Comparative Example 3] A dicing die bonding sheet was obtained in the same manner as in Example 1, except that the thickness of the base film was 50 μm in the preparation of the base film in Example 1.

[0062] [Comparative Example 4] Instead of preparing the base film as in Example 1, an ethylene-methacrylic acid copolymer (trade name: Nucrel N0908C, manufactured by Mitsui DuPont Polychemicals) was used to prepare the base film. Also, instead of preparing the adhesive as in Example 1, a copolymer consisting of 90 parts by mass of 2-ethylhexyl acrylate and 10 parts by mass of 2-hydroxyethyl acrylate was prepared, and 5 parts by mass of Coronate L (trade name, manufactured by Tosoh Corporation, polyisocyanate compound) as a curing agent and 5 parts by mass of Irgacure 184 (manufactured by Ciba-Geigy Japan, trade name) as a photopolymerization initiator were added to prepare the adhesive. Except as described above, the dicing die bonding tape was prepared in accordance with Example 1. The dicing die bonding tape of Comparative Example 4 had a base thickness of 100 μm, an adhesive layer thickness of 10 μm, and a bonding layer thickness of 20 μm.

[0063] [Comparative Example 5] A dicing die bonding sheet was obtained in the same manner as in Example 1, except that a 100 μm thick base film was prepared using an ionomer resin (trade name: Hymiran, manufactured by Mitsui DuPont Polychemicals) which is an ethylene-methacrylic acid-(2-methyl-propyl acrylate) terpolymer in which the metal ion is a Mg metal ion.

[0064] [Comparative Example 6] A dicing die bonding sheet was obtained in the same manner as in Example 1, except that in the preparation of the base film of Example 1, 60 parts by mass of 4-ethyl-1-pentene copolymer and 20 parts by mass of polypropylene were blended instead of 60 parts by mass of polypropylene, and the amount of thermoplastic elastomer blended was 20 parts by mass.

[0065] [Test Example 1] Heat Resistance Test The following evaluation was conducted to determine whether the wafer possessed sufficient heat resistance to withstand plasma dicing. An 8-inch diameter silicon wafer was prepared, with a resist patterned with dicing lines for obtaining 1 mm x 1 mm chips on one side. The adhesive layer side of the dicing die bonding sheet obtained in each example and comparative example was attached to the side of this wafer opposite to the resist to obtain a wafer with a dicing die bonding sheet. Next, the wafer with the dicing die bonding sheet was held by electrostatic adsorption on the electrostatic chuck table of a plasma dicing apparatus equipped with an electrostatic chuck table in a vacuum chamber, with the substrate facing the electrostatic chuck table side. Then, the inside of the vacuum chamber was set to a vacuum condition of 0.03 MPa pressure and a temperature of 25°C, and SF was used as the plasma generation gas. ６ Using a gas, a silicon wafer was irradiated with plasma through a resist at an etching rate of 0.3 μm / min for 30 minutes. The dicing die bonding sheet was visually observed to see if wrinkles formed as a result of this plasma irradiation, and its heat resistance was evaluated according to the following evaluation criteria. The results are shown in Table 1. <Heat Resistance Evaluation Criteria> ○: No wrinkles formed on the sheet. ×: Wrinkles were clearly present on the sheet.

[0066] [Test Example 2] Heat-resistant expandability test A dicing die bonding sheet, which holds 1 mm x 1 mm chips after the wafer has been fragmented by the plasma dicing described in Test Example 1, was subjected to an integrated irradiation dose of 200 mJ / cm using a high-pressure mercury lamp. ２Ultraviolet light was irradiated to achieve the following. Subsequently, expansion was performed with an expansion amount (the amount the table on which the sample was placed) of 10 mm. Then, 100 chips in the central part were picked up using a die bonder device (product name "DB-830Plus", manufactured by Fasford Technology) with a push-up height of 0.1 mm using a push-up pin. The presence or absence of sheet breakage during the above expansion-to-pickup process was used as an indicator, and the pickup success rate (a pickup was considered successful if one chip was peeled off independently from the adhesive layer along with a piece of adhesive layer, and the pickup success rate ({number of chips successfully picked up / 100 chips} × 100%)) was also taken into consideration, and the heat-resistant expandability was evaluated according to the evaluation criteria below. If the sheet does not break and is sufficiently expanded to ensure sufficient and uniform spacing between chips, the pickup success rate will be high. The results are shown in Table 1. <Heat-resistant expandability evaluation criteria> ◎: The dicing sheet did not break and the pickup success rate was 100%. ○: The dicing sheet did not break, and the pickup success rate was between 90% and 99%. △: The dicing sheet did not break, and the pickup success rate was between 80% and 89%. ×: The dicing sheet broke, or the pickup success rate was 79% or less.

[0067]

[0068] As shown in the table above, sheets in which the substrate did not contain thermoplastic elastomer exhibited poor heat-resistant expandability (Comparative Example 1). Furthermore, sheets in which the main melting peak temperature of the substrate was lower than that specified in the present invention could not withstand the plasma dicing temperature and were therefore unsuitable for plasma dicing applications (Comparative Examples 4 and 5). In addition, sheets in which the thermoplastic elastomer content in the substrate was higher than that specified in the present invention resulted in reduced heat resistance and poor heat-resistant expandability (Comparative Example 2). Moreover, even sheets in which the substrate contained thermoplastic elastomer in the amount specified in the present invention and the main melting peak temperature of the substrate was within the specified range, if the thickness of the substrate was thinner than that specified in the present invention, the result was at least poor heat-resistant expandability (Comparative Examples 3 and 6). In contrast, when the composition or physical properties of the substrate satisfied the specifications of the present invention, it showed heat resistance suitable for plasma dicing applications and also exhibited excellent heat-resistant expandability (Examples 1 to 5). In particular, it can be seen that the heat-resistant expandability was further improved by making the thickness of the substrate thinner than 100 μm (comparison between Examples 1 and 4 and Example 5). In the section on [Examples], the effects of the present invention were verified using a dicing die bonding sheet. As mentioned above, the composition of the base material is dominant in determining the heat resistance and expandability of the sheet. Therefore, it can be understood that even a dicing sheet having a base material and an adhesive layer, but without an adhesive layer, can have improved heat resistance or heat-resistant expandability compared to one that does not satisfy the provisions of the present invention.

[0069] Although we have described the present invention along with its embodiments, we do not intend to limit our invention in any detail of the description unless specifically designated, and we believe that it should be interpreted broadly without contradicting the spirit and scope of the invention as set forth in the appended claims.

[0070] This application claims priority based on Japanese Patent Application No. 2025-051011, filed in Japan on 26 March 2025, the contents of which are incorporated herein by reference as part of this specification.

[0071] 1 Semiconductor wafer 2 Pattern surface 3 Surface protection tape M1 Wafer grinding apparatus 4 Resist 5 Dicing sheet 5a Base material film 5b Adhesive layer F Ring frame P1 SF ６ Plasma P2 O ２ Plasma 7 Semiconductor chip M2 Push-up pin M3 Collet

Claims

1. A dicing sheet for plasma dicing having a substrate that satisfies the following (a) to (c) and an adhesive layer disposed on one side of the substrate: (a) Thermoplastic elastomer content of 5 to 50% by mass; (b) Main melting peak temperature of 105°C or higher in differential scanning calorimetry; (c) Thickness of 60 to 300 μm.

2. The dicing sheet for plasma dicing according to claim 1, wherein the substrate contains a polyolefin resin.

3. The dicing sheet for plasma dicing according to claim 2, wherein the polyolefin resin includes polypropylene.

4. The dicing sheet for plasma dicing according to claim 3, wherein the thermoplastic elastomer includes a styrene-based thermoplastic elastomer.

5. The dicing sheet for plasma dicing according to claim 3, wherein the thickness of the substrate is less than 100 μm.

6. The dicing sheet for plasma dicing according to claim 5, wherein the thickness of the substrate is less than 85 μm.

7. The dicing sheet for plasma dicing according to claim 5, wherein the thickness of the substrate exceeds 85 μm.

8. The dicing sheet for plasma dicing according to claim 3, wherein the adhesive layer is energy ray curing type.

9. The dicing sheet for plasma dicing according to claim 3, wherein the adhesive layer is located on the side of the adhesive layer opposite to the substrate side.

10. A method for manufacturing a semiconductor chip, comprising fixing a semiconductor wafer via a plasma dicing sheet described in any one of claims 1 to 9, and obtaining a semiconductor chip on the plasma dicing sheet by dicing the semiconductor wafer into individual pieces.

11. A method for manufacturing a semiconductor package, comprising picking up a semiconductor chip obtained by the manufacturing method described in claim 10 from the plasma dicing sheet and mounting it on a wiring board.

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