Method for manufacturing wafer processing sheets and semiconductor devices

Abstract

The present invention provides a wafer processing sheet and a semiconductor device manufacturing method that can prevent some elements constituting the wafer processing sheet from reaching the wafer, thereby achieving wafer cleanliness. [Solution] The wafer processing sheet (10) has a water-soluble resin layer (30) and a base layer (20). The water-soluble resin layer (30) is made of a water-soluble resin. The base layer (20) is made of a resin sheet that covers one side of the water-soluble resin layer (30) and has tack force on the side facing the water-soluble resin layer (30) under predetermined conditions.

Description

Technical Field

[0001] The present invention relates to a sheet for wafer processing and a method for manufacturing a semiconductor device.

Background Art

[0002] Conventionally, it has been proposed to thermocompression-bond one surface of a thermocompression-bonding film having a base material layer made of polyolefin and not having an adhesive layer formed of an adhesive or the like to one surface of a workpiece such as a semiconductor wafer (see, for example, Patent Document 1). By using this thermocompression-bonding film, there is an advantage that even if the thermocompression-bonding film is peeled off, it is difficult for the adhesive to remain on one surface of the workpiece.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, according to the intensive research of the present inventor, in the prior art including Patent Document 1, as a result of the thermocompression-bonding film being closely adhered to the workpiece by thermocompression-bonding, there is a concern that extremely some elements constituting the thermocompression-bonding film remain on the workpiece side.

[0005] An object of the present invention is to provide a sheet for wafer processing and a method for manufacturing a semiconductor device capable of preventing some elements constituting the sheet for wafer processing from reaching the wafer and obtaining the cleanliness of the wafer.

Means for Solving the Problems

[0006] A sheet for wafer processing according to one aspect of the present invention includes a water-soluble resin layer made of a water-soluble resin, and a base layer made of a resin sheet that covers one side of the water-soluble resin layer and has a tack force on the surface on the side of the water-soluble resin layer under predetermined conditions.

[0007] The base layer may be larger than the water-soluble resin layer in a plan view and may extend beyond the entire outer periphery of the water-soluble resin layer.

[0008] The wafer processing sheet may have (or exhibit) tackiness when heat-pressed.

[0009] The thickness of the water-soluble resin layer may be 100 μm or less.

[0010] The dissolution rate of the water-soluble resin when dissolved in water at a first temperature of 0°C to 35°C may be 1 / 5 or less of the dissolution rate when dissolved in water at a second temperature of 35°C to 100°C.

[0011] A semiconductor device manufacturing method according to one aspect of the present invention comprises a wafer processing sheet having a water-soluble resin layer made of a water-soluble resin, and a base layer made of a resin sheet that covers one side of the water-soluble resin layer and has tack force on the side facing the water-soluble resin layer under predetermined conditions, wherein the base layer is larger than the water-soluble resin layer in a plan view and extends beyond the entire outer periphery of the water-soluble resin layer, and the wafer processing sheet is fixed to a plate-shaped wafer having a device region on which a device is formed and an outer peripheral excess region surrounding the device region, with the side of the wafer processing sheet facing the water-soluble resin layer; a processing step of processing the wafer while supplying a liquid containing water to the wafer; a peeling step of peeling at least the base layer of the wafer processing sheet from the wafer after the processing step; and a cleaning step of cleaning the surface of the wafer to which the wafer processing sheet was fixed with a liquid containing water after the peeling step.

[0012] The water-soluble resin layer may be larger than the device area in a plan view, and the device area may be covered with the water-soluble resin layer by the sheet fixing process.

[0013] The processing step may include a thinning step in which the wafer is ground to make it thinner.

[0014] The processing step may include a segmentation step in which the wafer is divided along a predetermined segmentation line set on the wafer, thereby segmenting the wafer into individual pieces. [Effects of the Invention]

[0015] According to the above embodiment, it is possible to provide a wafer processing sheet and a semiconductor device manufacturing method that can prevent some elements constituting the wafer processing sheet from reaching the wafer, thereby achieving wafer cleanliness. [Brief explanation of the drawing]

[0016] [Figure 1] This figure shows an example of the configuration of a wafer processing sheet. [Figure 2] This figure shows an example of a wafer configuration. [Figure 3] This figure shows an example of the process of fixing a wafer processing sheet to a wafer (sheet fixing process). [Figure 4] This is a diagram showing an example of the manufacturing process. [Figure 5] This figure shows an example of the peeling and cleaning processes. [Modes for carrying out the invention]

[0017] <Definitions of Terms, etc.> In this specification, "wafer processing sheet" may be interpreted as, for example, "wafer processing tape," "wafer processing film," "wafer processing component," "wafer processing auxiliary sheet," "wafer processing auxiliary tape," "wafer processing auxiliary film," or "wafer processing auxiliary component." Furthermore, "wafer" in "wafer processing sheet" may refer to any object that can be processed by various processing devices, and may be interpreted as "workpiece," "object to be processed," or "work." Processing of wafers by processing devices may include, for example, laser processing, where the wafer is processed with a laser beam; cutting, where the wafer is cut with an annular cutting blade; polishing, where the wafer is polished with a polishing pad; and grinding, where the wafer is ground with a grinding wheel. Furthermore, the wafer processing steps by processing devices may include thinning steps, where the wafer is ground to make it thinner, or fragmentation steps, where the wafer is divided into individual pieces along predetermined division lines set on the wafer.

[0018] In this specification, "wafer" may mean, for example, a "semiconductor wafer" which is the base of a semiconductor integrated circuit. A semiconductor wafer may be realized as a disc of appropriate thickness obtained by cutting a single crystal column made by growing silicon (Si) or silicon carbide (SiC) into a thin slice. Furthermore, "wafer" may not be limited to semiconductor components but may refer to a wafer-shaped workpiece made of various materials such as silicon (Si), silicon carbide (SiC), glass, or resin. In this specification, when simply referring to "wafer," it may be used as a broad concept that includes not only semiconductor wafers but also wafer-shaped workpieces not limited to semiconductor components. Also, "wafer" and "semiconductor wafer" may be read as interchangeable (in particular, even when referring to a semiconductor wafer, it may be interpreted as referring to a wafer-shaped workpiece not limited to semiconductor components).

[0019] As used herein, the "wafer processing sheet" is attached to at least one surface (at least one side) of a wafer when the wafer is processed by various processing apparatuses, and has a function of protecting the attachment surface of the wafer, particularly the device region (chip region). After the processing of the wafer by various processing apparatuses is completed, the wafer processing sheet is removed from the wafer.

[0020] As used herein, the "water-soluble resin layer" has a property and function such that even when residual elements (residues) of the base layer and thus the wafer processing sheet are generated, the residual elements (residues) do not reach the wafer (particularly the device region), i.e., the base layer is not brought into direct contact with the wafer (particularly the device region) (isolating and separating the source and destination of the residual elements (residues)). And after the "water-soluble resin layer" has served its purpose of not bringing into direct contact (isolating and separating), it can be removed (washed away) from the wafer during washing with washing water (liquid containing water). That is, even if the water-soluble resin layer remains on the wafer as a residual element (residue) (interpreted as a residual element (residue) when the water-soluble resin layer remains on the wafer) or residual elements (residues) due to the base layer remain thereon, these can be reliably removed (washed away) from the wafer.

[0021] As used herein, the "base layer" is composed of a resin sheet that covers one side of the above-mentioned water-soluble resin layer (for example, the side opposite to the wafer-facing surface), and has (exerts) tack force on the surface on the side of the above-mentioned water-soluble resin layer (for example, the wafer-facing surface) under predetermined conditions. "Tack force" refers to the force (initial adhesion force, instantaneous adhesion force) that indicates the property of adhering to the wafer (adhered object) in a short time just by gently touching (approaching) the wafer (adhered object), and is used in the concept including, for example, adhesive force and thermocompression bonding force. Also, the "predetermined conditions" can vary according to the factors causing the tack force (the attachment mechanism of the wafer processing sheet to the wafer). Specifically, when using adhesive force, exposing the adhesive surface of the base layer and approaching it to the wafer (adhered object) corresponds to the "predetermined conditions". In the case of thermocompression bonding force, approaching the thermocompression bonding surface of the base layer to the wafer (adhered object) and heating it corresponds to the "predetermined conditions". The base layer does not always need to have tack force (adhesive force or thermocompression bonding force), and it is sufficient if it can exert tack force under the "predetermined conditions" when attached to the wafer. Thus, there is freedom in the mechanism for generating tack force in the base layer, and various design changes are possible.

[0022] As used herein, the "base layer" composed of a resin sheet having (exerting) tack force, in a broad sense, includes those in which adhesives or adhesives may remain even after removal of the wafer processing sheet by utilizing adhesive force, adhesive strength, etc. Also, the "base layer" composed of a resin sheet having (exerting) tack force, in a narrow sense, excludes those in which adhesives or adhesives may remain by utilizing adhesive force, adhesive strength, etc., and does not include those in which adhesives or adhesives may remain after removal of the wafer processing sheet by utilizing thermocompression bonding force, etc. (however, there is a possibility of generation of residual elements (residues)).

[0023] The base layer may be larger than the water-soluble resin layer in a plan view and may extend beyond the entire outer periphery of the water-soluble resin layer. That is, when considering the wafer-facing surface of the wafer processing sheet, the water-soluble resin layer may be located in a part of the wafer-facing surface (e.g., the central part), and the base layer (a resin sheet with tack force) may be located in another part of the wafer-facing surface (e.g., the peripheral part). For example, when the wafer and the wafer-facing surface have the same (approximately the same) circular (approximately circular) contour, the water-soluble resin layer may constitute the central circular (approximately circular) portion of the wafer-facing surface, and the base layer may constitute the peripheral annular (approximately annular) portion of the wafer-facing surface. In this case, when the wafer-facing surface of the wafer processing sheet is attached to the wafer, the peripheral side (excess peripheral region) of the wafer and the wafer-facing surface are bonded by the tack force of the base layer, and the water-soluble resin layer is filled (sealed) into the closed space (sealed space) on the central side. Furthermore, if a device region (chip region) is formed on the central side of the wafer, a water-soluble resin layer filled (sealed) in the closed space (sealed space) on the central side of the wafer-facing surface can provide extremely advantageous protection for the device region (it is possible to reliably prevent water supplied during wafer processing, the base layer, and even residual elements (residues) generated in the wafer processing sheet from reaching the device region (chip region)).

[0024] The wafer processing sheet is not limited to a laminated structure of two layers, a water-soluble resin layer and a base layer; additional or alternative layers may be provided. For example, the wafer processing sheet may have a PET (Poly Ethylene Terephthalate) layer positioned on the side of the base layer opposite to the water-soluble resin layer (the base layer may be located between the water-soluble resin layer and the PET layer).

[0025] In this specification, "water-soluble resin (layer)" is composed of a molten metal solubility film, that is, a resin (layer) that exhibits higher solubility (dissolution rate) in a relatively high-temperature liquid (molten metal) than in a relatively low-temperature liquid (water). As an example of a molten metal solubility film, the dissolution rate of the water-soluble resin when dissolved in water at a first temperature of 0°C to 35°C may be 1 / 5 or less of the dissolution rate when dissolved in water at a second temperature of 35°C to 100°C. In this case, the 35°C water may be divided into either the first temperature water or the second temperature water. That is, the first temperature water may be defined as water at 0°C to less than 35°C, and the second temperature water may be defined as water at 35°C to 100°C. Alternatively, the first temperature water may be defined as water at 0°C to 35°C, and the second temperature water may be defined as water at a temperature greater than 35°C and 100°C or less.

[0026] <Composition of wafer processing sheet> The configuration of the wafer processing sheet 10 will be explained with reference to Figures 1 to 3. Figure 1 (Figures 1A and 1B) shows an example of the configuration of the wafer processing sheet 10. Figure 2 shows an example of the configuration of the wafer 40. Figure 3 (Figures 3A and 3B) shows an example of the process of fixing the wafer processing sheet 10 to the wafer 40 (sheet fixing process).

[0027] The wafer processing sheet 10 has a base layer 20 and a water-soluble resin layer 30.

[0028] The base layer 20 constitutes the functional layer of a so-called thermocompression sheet and possesses (exhibits) tack force when thermocompressed. The base layer 20 has a first surface 21 and a second surface 22 located on opposite sides of each other, with the first surface 21 being the surface facing the wafer 40 and the second surface 22 being the surface not facing the wafer 40 (the surface opposite to the wafer 40).

[0029] The base layer 20 is made of a resin sheet that, under predetermined conditions, has (exhibits) tack force on its first surface 21 (the surface facing the water-soluble resin layer 30). That is, by heating the first surface (thermocompression bonding surface) 21 of the base layer 20 in close proximity to the wafer 40, tack force is generated on the first surface (thermocompression bonding surface) 21 of the base layer 20, thereby fixing the base layer 20 and, consequently, the wafer processing sheet 10 to the wafer 40.

[0030] The resin sheet (resin material) constituting the base layer 20 has a degree of freedom and various design changes are possible, but for example it can be configured as follows. That is, the resin sheet (resin material) constituting the base layer 20 may be made of a plastic material such as a polymer, for example, polyolefin, polyethylene (PE), or polypropylene (PP). For example, a polyolefin film can be stretched flexibly when heated (when heated to a temperature in the range of 60°C to 150°C) and is flexible. Therefore, the base layer 20 can be made to conform to the mounting surface of the wafer 40 (for example, by absorbing the topography) and exert a tack force (fix it). Furthermore, the tack force exerted by the base layer 20 on the wafer 40 may be due not only to conforming to (conforming to) the mounting surface of the wafer 40, but also to intermolecular forces due to adhesion.

[0031] The water-soluble resin layer 30 is made of (or contains) a water-soluble resin and has a first surface 31 and a second surface 32 located on opposite sides of each other. The first surface 31 is a surface that faces and protects the wafer 40 (more specifically, the device region 43 of the first surface 41, which will be described later), and the second surface 32 of the water-soluble resin layer 30 is a surface that is fixed, bonded, or coated to the first surface 21 of the base layer 20. That is, one side of the water-soluble resin layer 30 (the second surface 32) is covered by the first surface 21 of the base layer 20.

[0032] Here, there is flexibility in the timing and method of integrating the base layer 20 and the water-soluble resin layer 30, allowing for various design changes. For example, before fixing the wafer processing sheet 10 to the wafer 40, the water-soluble resin layer 30 may be fixed or bonded to the first surface 21 of the base layer 20 in advance (both the base layer 20 and the water-soluble resin layer 30 may be in a dry state), or the water-soluble resin layer 30 may be applied to the first surface 21 of the base layer 20 and then dried. Alternatively, the water-soluble resin layer 30 may be applied to the first surface 21 of the base layer 20 immediately before fixing the wafer processing sheet 10 to the wafer 40 (in this case, the water-soluble resin layer 30 may be in a wet state). In a broader sense, it is also possible to apply a water-soluble resin layer 30 to a desired area of ​​the wafer 40 (for example, the device area 43 of the first surface 41, as described later) immediately before fixing the wafer processing sheet 10 to the wafer 40, and then fix or bond the base layer 20 on top of it by thermocompression.

[0033] The thickness of the water-soluble resin layer 30 is 100 μm or less, and may be set to be sufficiently smaller than the thickness of the base layer 20. In Figures 1A and 3A, the thickness of the water-soluble resin layer 30 (the amount of protrusion from the base layer 20) is exaggerated and depicted as large, but in reality, the image is that a thin water-soluble resin layer 30 is placed (coated) on the first surface 21 of the base layer 20, and the step difference between the part of the first surface 21 of the base layer 20 where the water-soluble resin layer 30 is present and the part where it is not is not extremely large. Therefore, the tack force of the base layer 20 may be exerted not only in the part where the water-soluble resin layer 30 is not present, but also in the part where the water-soluble resin layer 30 is present. In other words, the water-soluble resin layer 30 does not need to have (exert) tack force, and it is sufficient if it can perform the protective function (barrier function, shielding function) of the wafer 40 (device area 43) as described later.

[0034] In a plan view, the base layer 20 is larger than the water-soluble resin layer 30 and extends beyond the entire outer periphery of the water-soluble resin layer 30. More specifically, when considering the wafer-facing surface of the wafer processing sheet 10 (the surface on the side of the first surface 21 of the base layer 20 and the first surface 31 of the water-soluble resin layer 30), the water-soluble resin layer 30 (first surface 31) is located in the central circular (approximately circular) portion, and the base layer 20 (first surface 21) is located in the peripheral annular (approximately annular) portion.

[0035] The water-soluble resin layer 30 may be, for example, a water-soluble thermoplastic resin (wet state) whose solubility in water varies greatly with temperature, and may be obtained by forming such a thermoplastic resin into a film of any thickness (e.g., 100 μm or less). Examples of thermoplastic resins constituting the water-soluble resin layer 30 include PVA (polyvinyl alcohol) with a high degree of saponification. As the degree of saponification of PVA increases, it becomes less soluble in water at low temperatures (it has the properties of a molten metal film). Here, the degree of saponification of PVA is preferably 97% or more when the degree of polymerization of PVA is 600 or more and less than 1700, and is preferably 96% or more when the degree of polymerization of PVA is 1700 or more.

[0036] The PVA used in the water-soluble resin layer 30 may contain other monomer units as long as it does not lose the characteristics described above. Examples of monomer units that may be contained in PVA include α-olefins such as ethylene, propylene, 1-butene, isobutene, and 1-hexene, acrylic acid and its salts, and acrylic acid esters such as methyl acrylate, ethyl acrylate, n-propyl acrylate, i-propyl acrylate, n-butyl acrylate, i-butyl acrylate, t-butyl acrylate, 2-ethylhexyl acrylate, dodecyl acrylate, and octadecyl acrylate, methacrylic acid and its salts, methyl methacrylate, ethyl methacrylate, and n-methyl methacrylate. -Propyl, i-propyl methacrylate, n-butyl methacrylate, i-butyl methacrylate, t-butyl methacrylate, 2-ethylhexyl methacrylate, dodecyl methacrylate, octadecyl methacrylate and other methacrylic acid esters, acrylamide, N-methylacrylamide, N-ethylacrylamide, N,N-dimethylacrylamide, diacetoneacrylamide, acrylamidepropanesulfonic acid and its salts, acrylamidopropyldimethylamine and its salts, N-methylolacrylamide and its derivatives Acrylamide derivatives such as methylmethacrylamide, N-methylmethacrylamide, N-ethylmethacrylamide, methacrylamidepropanesulfonic acid and its salts, methacrylamidepropyldimethylamine and its salts, N-methylolmethacrylamide and its derivatives, and other methacrylamide derivatives, N-vinylpyrrolidone, N-vinylformamide, N-vinylacetamide and other N-vinylamides, allyl ethers having polyalkylene oxide as a side chain, methyl vinyl ether, ethyl vinyl ether, n-propyl vinyl These include vinyl ethers such as nyl ethers, i-propyl vinyl ether, n-butyl vinyl ether, i-butyl vinyl ether, t-butyl vinyl ether, dodecyl vinyl ether, and stearyl vinyl ether; nitriles such as acrylonitrile and methacrylonitrile; vinyl halides such as vinyl chloride, vinylidene chloride, vinyl fluoride, and vinylidene fluoride; allyl compounds such as allyl acetate and allyl chloride; maleic acid and its salts or esters; vinyl silyl compounds such as vinyltrimethoxysilane; and isopropenyl acetate.

[0037] Furthermore, a plasticizer may be added to the thermoplastic resin used in the water-soluble resin layer 30. That is, the thermoplastic resin used in the water-soluble resin layer 30 may contain a plasticizer in addition to the PVA described above. By adding a plasticizer to the water-soluble resin layer 30, the water-soluble resin layer 30 becomes more easily deformable to follow the shape of the wafer 40 (particularly the device region 43 described later), allowing the water-soluble resin layer 30 to adhere more securely to the wafer 40 (particularly the device region 43 described later). In addition, it is preferable to use a water-soluble plasticizer. This is because by adding a water-soluble plasticizer to the water-soluble resin layer 30, the water-soluble plasticizer and, consequently, the water-soluble resin layer 30 can be removed (washed away) without leaving any residue on the wafer 40 (particularly the device region 43 described later).

[0038] Such plasticizers can be any plasticizer commonly used for PVA, without limitation. Specific examples of plasticizers include polyhydric alcohols such as glycerin, diglycerin, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, trimethylolpropane, pentaerythritol, and 1,3-butanediol; polyethers such as polyethylene glycol and polypropylene glycol; polyvinylamides such as polyvinylpyrrolidone; amide compounds such as N-methylpyrrolidone and dimethylacetamide; compounds obtained by adding ethylene oxide to polyhydric alcohols such as glycerin, pentaerythritol, and sorbitol, or water. The water-soluble resin layer 30 may contain only one of these plasticizers, or two or more.

[0039] Furthermore, these plasticizers may be added to the water-soluble resin layer 30 not only to improve conformability to the wafer 40 (particularly the device region 43 described later), but also to improve water solubility. To improve the water solubility of the water-soluble resin layer 30, it is preferable to use glycerin, diglycerin, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, trimethylolpropane, polyethylene glycol, polyvinylpyrrolidone, etc. as plasticizers. To suppress the decrease in water solubility of the water-soluble resin layer 30 due to plasticizer bleed-out, glycerin, diglycerin, trimethylolpropane, polyethylene glycol, polyvinylpyrrolidone, etc. may also be used as plasticizers.

[0040] Preferably, the water-soluble resin layer 30, composed of a combination of thermoplastic resins and plasticizers as described above, has properties as a molten metal film such that the dissolution rate when dissolved in water at a first temperature of 0°C to 35°C is 1 / 5 or less of the dissolution rate when dissolved in the same water at a second temperature of 35°C to 100°C. The first temperature water may be defined as water at 0°C to less than 35°C, and the second temperature water may be defined as water at 35°C to 100°C. Alternatively, the first temperature water may be defined as water at 0°C to 35°C, and the second temperature water may be defined as water at a temperature greater than 35°C and 100°C or less.

[0041] The above conditional equation indicates that the water-soluble resin layer 30 has higher solubility (dissolution rate) in a liquid (hot water) at a relatively higher temperature (second temperature) than in a liquid (water) at a relatively lower temperature (first temperature). Therefore, for example, by using a liquid (water) at the first temperature supplied in the processing step described later, even if the supplied water at the first temperature comes into contact with the water-soluble resin layer 30, the water-soluble resin layer 30 will not (almost) dissolve, and will be able to perform the protective function (barrier function, shielding function) of the wafer 40 (device region 43) as described later. On the other hand, by using a liquid (hot water) at the second temperature supplied in the cleaning step described later, the water-soluble resin layer 30, which has finished performing the protective function (barrier function, shielding function) of the wafer 40 (device region 43) as described later and is no longer needed, can be easily and quickly dissolved and removed (washed away) by the water at the second temperature.

[0042] To facilitate the expression of the differences in solubility (dissolution rate) described above, the first temperature of the water is preferably 10°C to 30°C, and more preferably 15°C to 30°C. Furthermore, the second temperature of the water is preferably 40°C to 70°C, and more preferably 45°C to 60°C.

[0043] The wafer 40 may be, for example, a substantially disc-shaped substrate made of materials such as Si (silicon), SiC (silicon carbide), GaN (gallium nitride), GaAs (gallium arsenide), or other semiconductor materials, or a material such as sapphire, glass, or quartz. The glass may be, for example, alkali glass, alkali-free glass, soda-lime glass, lead glass, borosilicate glass, or quartz glass.

[0044] The wafer 40 has a first surface 41 and a second surface 42 located on opposite sides of each other. The first surface 41 is the surface facing the wafer processing sheet 10 (the first surface 21 of the base layer 20 and the first surface 31 of the water-soluble resin layer 30), and the second surface 42 is the surface that does not face the wafer processing sheet 10 (the surface opposite to the wafer processing sheet 10).

[0045] The first surface 41 of the wafer 40 is divided into a device region (chip region) 43 formed in a central circular (approximately circular) portion and an outer peripheral excess region 44 formed in an annular (approximately annular) portion on the periphery. In other words, the first surface 41 of the plate-shaped (disk-shaped) wafer 40 has a device region 43 on which a device is formed and an outer peripheral excess region 44 surrounding this device region 43.

[0046] Although not shown in the diagram, the device region 43 is divided by a plurality of division lines (streets) arranged in a grid, and devices such as ICs (Integrated Circuits), LSIs (Large Scale Integrations), and LEDs (Light Emitting Diodes) are formed in each region divided by the division lines. The processing (processing steps) of the wafer 40 in this embodiment may include, for example, a thinning (step) in which the wafer 40 (the second surface 42) is thinned by grinding, and / or a fragmentation (step) in which the wafer 40 (the device region 43) is divided along the division lines set in the wafer 40 to form individual pieces.

[0047] There is some flexibility in the arrangement balance between the device region 43 and the outer peripheral excess region 44 on the first surface 41 of the wafer 40, and various design changes are possible. For example, an annular (approximately annular) line 1 mm to 5 mm inward from the outermost edge of the first surface 41 of the wafer 40 may be used as a reference line, with the area inward from this reference line set as the device region 43 and the area outward from this reference line set as the outer peripheral excess region 44.

[0048] In this embodiment, when viewed from above, the wafer processing sheet 10 and the wafer 40 have the same (approximately the same) circular shape. When focusing on the wafer-facing surface of the wafer processing sheet 10, the first surface 31 of the water-soluble resin layer 30 corresponds to the device region 43 of the wafer 40, and the first surface 21 of the base layer 20 (the outer peripheral exposed portion of the first surface 31 of the water-soluble resin layer 30) corresponds to the outer peripheral excess region 44 of the wafer 40. When viewed from above, the first surface 31 of the water-soluble resin layer 30 covers (coats) the device region 43 of the wafer 40 and has a shape that is the same as, or slightly larger than, the device region 43 of the wafer 40.

[0049] Therefore, both before and after fixing the wafer processing sheet 10 and the wafer 40, or at least after fixing the wafer processing sheet 10 and the wafer 40, the water-soluble resin layer 30 is larger than the device region 43 of the wafer 40 in a plan view. The device region 43 of the wafer 40 is covered by the water-soluble resin layer 30 by the sheet fixing process described later. Furthermore, the base layer 20 (the outer peripheral exposed portion of the water-soluble resin layer 30) is fixed to the outer peripheral excess region 44 of the wafer 40 by thermocompression (fixed by tack force), so the water-soluble resin layer 30 is filled (encapsulated) on the inner peripheral side of the outer peripheral base layer 20, and the water-soluble resin layer 30 protects (barriers, shields) the device region 43 of the wafer 40.

[0050] First, the protective function (barrier function, shielding function) of the base layer 20, which is thermocompressed (fixed) to the excess area 44 on the outer periphery of the wafer 40, prevents water supplied in the processing step described later from reaching the water-soluble resin layer 30. Even if some of the water supplied in the processing step described later were to pass through the base layer 20 and enter the inner periphery, the protective function (barrier function, shielding function) of the water-soluble resin layer 30 prevents some of that water from reaching the device area 43 of the wafer 40. In this way, the double protective function (barrier function, shielding function) of the base layer 20 and the water-soluble resin layer 30 of the wafer processing sheet 10 reliably prevents water supplied in the processing step described later from reaching the device area 43 of the wafer 40.

[0051] Furthermore, due to the protective function (barrier function, shielding function) of the water-soluble resin layer 30, even if residual elements (residues) are generated in the base layer 20 and consequently in the wafer processing sheet 10 while the wafer processing sheet 10 and wafer 40 are fixed together, the base layer 20 is not made to come into direct contact with the wafer 40 (device region 43) so that these residual elements (residues) do not reach the wafer 40 (device region 43) (isolation and separation of the source and destination of the residual elements (residues)). In addition, during cleaning in the cleaning process described later, the water-soluble resin layer 30, which has finished its role of preventing direct contact (isolation and separation), can be removed (washed away) from the wafer 40.

[0052] Incidentally, the excess region 44 on the outer edge of the wafer 40 is not protected (barrier, shielding) by the water-soluble resin layer 30, so residual elements (residues) from the base layer 20 and, consequently, the wafer processing sheet 10 may adhere to it. However, since the excess region 44 on the outer edge is unrelated to the function of the wafer 40 (for example, its electrical properties as a semiconductor wafer), no adverse effects will occur due to residual elements (residues). This is also true when using adhesive force or tack force as the mechanism of tack force of the wafer processing sheet 10 (base layer 20), and even if adhesive or tack agent remains in the excess region 44 on the outer edge of the wafer 40, no adverse effects will occur.

[0053] <Methods for manufacturing semiconductor devices> Next, the semiconductor device manufacturing method of this embodiment will be described with reference to Figures 3 to 5. Figure 3 (Figures 3A and 3B) shows an example of the sheet fixing process. Figure 4 shows an example of the processing process. Figure 5 (Figures 5A and 5B) shows an example of the peeling process and the cleaning process.

[0054] ≪Sheet fixing process≫ First, a wafer processing sheet 10 is prepared, having the above-described configuration, namely a water-soluble resin layer 30 made of a water-soluble resin, and a base layer 20 made of a resin sheet that covers one side (second surface 32) of the water-soluble resin layer 30 and has (exhibits) tack force on the side of the water-soluble resin layer 30 (first surface 21) under predetermined conditions. The base layer 20 is larger than the water-soluble resin layer 30 in a plan view and extends beyond the entire outer periphery of the water-soluble resin layer 30. Next, a plate-shaped wafer 40 is prepared, having the above-described configuration, namely a device region 43 on which a device is formed, and an outer peripheral excess region 44 surrounding the device region 43. Then, the wafer processing sheet 10 is fixed to the plate-shaped wafer 40 with the side of the water-soluble resin layer 30 facing it.

[0055] More specifically, the wafer-facing surfaces of the wafer processing sheet 10 (the first surface 21 of the base layer 20 and the first surface 31 of the water-soluble resin layer 30) are brought into contact with the first surface 41 of the wafer 40 (the device region 43 and the outer peripheral excess region 44). At this time, the first surface 31 of the water-soluble resin layer 30 is aligned with the device region 43, and the first surface 21 of the base layer 20 (the outer peripheral exposed portion of the first surface 31 of the water-soluble resin layer 30) is aligned with the outer peripheral excess region 44. Then, the wafer-facing surfaces of the wafer processing sheet 10 (the first surface 21 of the base layer 20 and the first surface 31 of the water-soluble resin layer 30) are brought close to the first surface 41 of the wafer 40 (the device region 43 and the outer peripheral excess region 44) and pressed against each other (in close contact) (see Figure 3A). In this pressed (closely attached) state, a heater (not shown) heats at least one of the wafer processing sheet 10 and the wafer 40, generating a thermocompression force (tack force) on the wafer processing sheet 10 (base layer 20) to fix the wafer processing sheet 10 and the wafer 40 together (see Figure 3B). Here, for the sake of ease of drawing, in the process from Figure 3A to Figure 3B (thermocompression process), the water-soluble resin layer 30 of the wafer processing sheet 10 is shown to melt and spread radially (left-right direction in the figure) to cover the outer diameter side (part of the outer peripheral excess region 44) of the device region 43 of the wafer 40, and the base layer 20 is shown to wrap around the outer peripheral side of the water-soluble resin layer 30.

[0056] In the sheet fixing process, a heater roller (not shown) may be used to heat-press the wafer-facing surface of the wafer processing sheet 10 onto the first surface 41 of the wafer 40. Furthermore, a wafer processing sheet 10 that is not the same size as the wafer 40 may be attached to the wafer 40, and then the wafer processing sheet 10 may be cut to match the shape of the wafer 40. For example, a wafer processing sheet 10 that is larger than the wafer 40 when viewed from above may be prepared, and the wafer processing sheet 10 may be attached so as to cover the wafer 40 and protrude from the periphery, and then the excess portion of the wafer processing sheet 10 (the portion that protrudes from the wafer 40 when viewed from above) may be cut off.

[0057] ≪Processing process≫ The wafer 40 is processed while a water-containing liquid is supplied to it. Figure 4 illustrates a thinning process (backgrinding thinning process) in which the wafer 40 is thinned by grinding as part of the processing steps. Specifically, the composite of the wafer processing sheet 10 formed in the sheet fixing process and the wafer 40 is rotated (inverted) so that the second surface 42 of the wafer 40, which is the target of processing, faces upward in the figure, and the grinding processing device (thinning device) 50 and the water supply device 60, which are processing devices, are placed facing the second surface 42. Then, while a water-containing liquid (for example, water at a first temperature, 20°C water) is supplied to the second surface 42 of the wafer 40 from the nozzle 61 of the water supply device 60, the second surface 42 of the wafer 40 is ground by the grinding processing part (grinding pad) 51 of the grinding processing device 50, thereby thinning the wafer 40 (see Figure 4; it can be seen that the wafer 40 has been thinned compared to Figure 3B).

[0058] In this processing step, the liquid containing water supplied from the water supply device 60 (for example, water at a first temperature) is prevented from reaching the device region 43 of the wafer 40 by the double protective function (barrier function, shielding function) of the base layer 20 and the water-soluble resin layer 30 of the wafer processing sheet 10. Furthermore, even if residual elements (residues) are generated in the base layer 20 and consequently in the wafer processing sheet 10, the water-soluble resin layer 30, protected (barrier, shielded) by the base layer 20, functions to prevent the base layer 20 from directly contacting the wafer 40 (device region 43) (isolating and separating the source and destination of the residual elements (residues)).

[0059] <<Peeling process>> After the processing steps described above, at least the base layer 20 of the wafer processing sheet 10 is peeled off from the wafer 40. More specifically, the bond between the wafer processing sheet 10, which has been processed (thinned) in the processing steps, and the wafer 40 is rotated (inverted) again so that the wafer processing sheet 10 (base layer 20 and water-soluble resin layer 30) faces upward in the figure. Then, the base layer 20 of the wafer processing sheet 10 is peeled off from the wafer 40 by holding (grabbing) the edge of the base layer 20 of the wafer processing sheet 10 with a peeling device (not shown) and pulling it away (peeling it off) (see Figure 5A). In this state of peeled base layer 20, the water-soluble resin layer 30 of the wafer processing sheet 10 remains covering the device region 43 of the wafer 40.

[0060] ≪Cleaning Process≫ After the peeling process described above, the surface of the wafer 40 to which the wafer processing sheet 10 was fixed (the first surface 41) is cleaned with a water-containing liquid (for example, hot water at a second temperature or 70°C). More specifically, the cleaning device 70 is placed opposite the first surface 41 of the wafer 40, and a water-containing liquid (for example, hot water at a second temperature or 70°C) is supplied from the nozzle 71 of the cleaning device 70 to clean the first surface 41 of the wafer 40 (see Figure 5B). At this time, the water-soluble resin layer 30 that remained covering the device region 43 is removed (washed away) from the wafer 40. As described above, the water-soluble resin layer 30 functions to prevent residual elements (residues) generated in the base layer 20 and, consequently, in the wafer processing sheet 10 from reaching the wafer 40 (device region 43) by preventing the base layer 20 from directly contacting the wafer 40 (device region 43) (isolating and separating the source and destination of the residual elements (residues)). After fulfilling its function (role), it can be removed (washed away) from the wafer 40.

[0061] <Example 1> In the above embodiment (Figure 4), a thinning process (thinning process by back grinding) in which the wafer 40 is thinned was described as an example of a processing process. However, the processing process is not limited to a thinning process, and may also be applied to a piece-forming process (piece-forming process by dicer full cut, piece-forming process in which thinning and chip division are performed simultaneously by grinding after dicer half cut) in which the wafer 40 is divided into individual pieces along a predetermined division line set on the wafer 40. In the piece-forming process as well, cutting (processing with a cutting blade) is performed while supplying a liquid containing water (for example, water at a first temperature, water at 20°C) to the wafer 40. At that time, water is supplied and cutting is performed from the first surface 41 of the wafer 40, that is, from the side of the fixed surface of the wafer processing sheet 10, but the double protective function (barrier function, shielding function) of the base layer 20 and the water-soluble resin layer 30 prevents water and residual elements (residue) from reaching the device region 43 of the wafer 40. Furthermore, the processing steps of this embodiment are applicable to all types of processing steps other than thinning steps (thinning steps by back grinding) and piece formation steps (piece formation steps by full cutting with a dicer, and piece formation steps in which thinning and chip division are performed simultaneously by grinding after half cutting with a dicer).

[0062] <Modification 2> The above embodiment illustrates a case where the base layer is larger than the water-soluble resin layer in a plan view and extends beyond the entire outer circumference of the water-soluble resin layer. However, the base layer may have the same contour as the water-soluble resin layer or a portion that extends further inward in a plan view (at least a part of the water-soluble resin layer may be exposed on the side). In this case, the protective function (barrier function, shielding function) of the base layer is partially weakened, but as long as the water-soluble resin layer covers the device area of ​​the wafer, the protective function (barrier function, shielding function) of the water-soluble resin layer is ensured (guaranteed), and a certain effect for achieving wafer cleanliness can be achieved.

[0063] <Variation 3> The above embodiment illustrates a case where, focusing on the wafer-facing surface of a wafer processing sheet, a circular (approximately circular) water-soluble resin layer is located in the central part (center side) of the wafer-facing surface, and an annular (approximately annular) base layer is located in the peripheral part (periphery side) of the wafer-facing surface. However, there is flexibility in the arrangement, shape, number, and other patterns of the water-soluble resin layer and base layer on the wafer-facing surface of the wafer processing sheet, and various design changes are possible. For example, if the device area of ​​the wafer is not concentrated only in the central part (center side) but is also distributed to the peripheral part (periphery side), the water-soluble resin layer can be divided into multiple layers and distributed in the gaps of the base layer to evenly and efficiently protect (barrier, shield) the device area of ​​the wafer.

[0064] As described above, the wafer processing sheet of this embodiment comprises a water-soluble resin layer made of a water-soluble resin, and a base layer made of a resin sheet that covers one side of the water-soluble resin layer and has tack force on the side facing the water-soluble resin layer under predetermined conditions.

[0065] Furthermore, the semiconductor device manufacturing method of this embodiment comprises a sheet fixing step of fixing a wafer processing sheet, which has a water-soluble resin layer made of a water-soluble resin and a base layer made of a resin sheet that covers one side of the water-soluble resin layer and has tack force on the side facing the water-soluble resin layer under predetermined conditions, wherein the base layer is larger than the water-soluble resin layer in a plan view and extends beyond the entire outer circumference of the water-soluble resin layer, to a plate-shaped wafer having a device region on which a device is formed and an outer peripheral excess region surrounding the device region, with the side of the wafer processing sheet facing the water-soluble resin layer; a processing step of processing the wafer while supplying a liquid containing water to the wafer; a peeling step of peeling at least the base layer of the wafer processing sheet from the wafer after the processing step; and a cleaning step of cleaning the surface of the wafer to which the wafer processing sheet was fixed with a liquid containing water after the peeling step.

[0066] This prevents some elements that make up the wafer processing sheet from reaching the wafer, making it possible to achieve wafer cleanliness.

[0067] Furthermore, the embodiments of the present invention are not limited to the embodiments and modifications described above, and may be modified, substituted, or altered in various ways without departing from the spirit of the technical idea of ​​the present invention. Moreover, if the technical idea of ​​the present invention can be realized in a different way by advances in the art or by other derived arts, it may be implemented by that method. Accordingly, the claims cover all embodiments that may fall within the scope of the technical idea of ​​the present invention. [Industrial applicability]

[0068] As described above, the present invention can be applied, for example, to wafer processing sheets and semiconductor device manufacturing methods that can ensure the cleanliness of wafers from residual elements (residues). [Explanation of symbols]

[0069] 10: Sheet for wafer processing 20: Base layer 21: 1st page 22:Second side 30: Water-soluble resin layer 31: 1st page 32: 2nd side 40: Wafer 41: 1st page 42:Second side 43: Device area (chip area) 44: Peripheral surplus region 50: Grinding equipment (thinning equipment) 51: Grinding section (grinding pad) 60:Water supply device 61: Nozzle 70: Washing device 71: Nozzle

Claims

1. A water-soluble resin layer made of a water-soluble resin, A base layer consisting of a resin sheet that covers one side of the water-soluble resin layer and has tackiness on the side of the water-soluble resin layer under predetermined conditions, Equipped with, A wafer processing sheet characterized by the following features.

2. The base layer is larger than the water-soluble resin layer in a plan view and extends beyond the entire outer periphery of the water-soluble resin layer. The wafer processing sheet according to feature 1.

3. The wafer processing sheet has tack force when heat-pressed. The wafer processing sheet according to feature 2.

4. The thickness of the water-soluble resin layer is 100 μm or less. A wafer processing sheet according to any one of claims 1 to 3.

5. The water-soluble resin has a dissolution rate of 1 / 5 or less when dissolved in water at a first temperature of 0°C to 35°C, compared to the dissolution rate when dissolved in water at a second temperature of 35°C to 100°C. A wafer processing sheet according to any one of claims 1 to 3.

6. A wafer processing sheet is characterized by having a water-soluble resin layer made of a water-soluble resin, and a base layer made of a resin sheet that covers one side of the water-soluble resin layer and has tack force on the side facing the water-soluble resin layer under predetermined conditions, wherein the base layer is larger than the water-soluble resin layer in a plan view and extends beyond the entire outer circumference of the water-soluble resin layer, and the wafer processing sheet is fixed to a plate-shaped wafer having a device region on which a device is formed and an outer peripheral excess region surrounding the device region, with the side of the water-soluble resin layer of the wafer processing sheet facing the wafer processing sheet, in a sheet fixing step, A processing step in which a liquid containing water is supplied to the wafer while processing it, After the processing step, a peeling step is performed to peel at least the base layer of the wafer processing sheet from the wafer, After the peeling process, a cleaning process is performed in which the surface of the wafer to which the wafer processing sheet was fixed is cleaned with a liquid containing water. A semiconductor device manufacturing method comprising the same components.

7. The water-soluble resin layer is larger than the device area in a plan view. The device region is covered with the water-soluble resin layer by the sheet fixing process. The semiconductor device manufacturing method according to feature 6.

8. The processing step includes a thinning step in which the wafer is thinned by grinding it. A method for manufacturing a semiconductor device according to claim 6 or 7, characterized by the features described above.

9. The processing step includes a segmentation step in which the wafer is divided along a predetermined division line set on the wafer, thereby segmenting the wafer into individual pieces. A method for manufacturing a semiconductor device according to claim 6 or 7, characterized by the features described above.

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