CN114944328A - Method for manufacturing semiconductor chip and protective film forming agent - Google Patents

Method for manufacturing semiconductor chip and protective film forming agent Download PDF

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Publication number
CN114944328A
CN114944328A CN202210125261.0A CN202210125261A CN114944328A CN 114944328 A CN114944328 A CN 114944328A CN 202210125261 A CN202210125261 A CN 202210125261A CN 114944328 A CN114944328 A CN 114944328A
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Prior art keywords
protective film
semiconductor wafer
forming agent
film forming
semiconductor chip
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CN202210125261.0A
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Chinese (zh)
Inventor
后藤龙生
木下哲郞
大久保明日香
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Tokyo Ohka Kogyo Co Ltd
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Tokyo Ohka Kogyo Co Ltd
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Priority claimed from JP2021201189A external-priority patent/JP2022125002A/en
Application filed by Tokyo Ohka Kogyo Co Ltd filed Critical Tokyo Ohka Kogyo Co Ltd
Publication of CN114944328A publication Critical patent/CN114944328A/en
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
    • H01L21/70—Manufacture or treatment of devices consisting of a plurality of solid state components formed in or on a common substrate or of parts thereof; Manufacture of integrated circuit devices or of parts thereof
    • H01L21/77—Manufacture or treatment of devices consisting of a plurality of solid state components or integrated circuits formed in, or on, a common substrate
    • H01L21/78—Manufacture or treatment of devices consisting of a plurality of solid state components or integrated circuits formed in, or on, a common substrate with subsequent division of the substrate into plural individual devices
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
    • H01L21/67—Apparatus specially adapted for handling semiconductor or electric solid state devices during manufacture or treatment thereof; Apparatus specially adapted for handling wafers during manufacture or treatment of semiconductor or electric solid state devices or components ; Apparatus not specifically provided for elsewhere
    • H01L21/67005—Apparatus not specifically provided for elsewhere
    • H01L21/67011—Apparatus for manufacture or treatment
    • H01L21/67092—Apparatus for mechanical treatment
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K26/00—Working by laser beam, e.g. welding, cutting or boring
    • B23K26/36—Removing material
    • B23K26/362—Laser etching
    • B23K26/364—Laser etching for making a groove or trench, e.g. for scribing a break initiation groove
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
    • C08K5/00—Use of organic ingredients
    • C08K5/04—Oxygen-containing compounds
    • C08K5/15—Heterocyclic compounds having oxygen in the ring
    • C08K5/151—Heterocyclic compounds having oxygen in the ring having one oxygen atom in the ring
    • C08K5/1545—Six-membered rings
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
    • C08K5/00—Use of organic ingredients
    • C08K5/16—Nitrogen-containing compounds
    • C08K5/17—Amines; Quaternary ammonium compounds
    • C08K5/18—Amines; Quaternary ammonium compounds with aromatically bound amino groups
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
    • C09D101/00—Coating compositions based on cellulose, modified cellulose, or cellulose derivatives
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
    • C09D129/00—Coating compositions based on homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by an alcohol, ether, aldehydo, ketonic, acetal, or ketal radical; Coating compositions based on hydrolysed polymers of esters of unsaturated alcohols with saturated carboxylic acids; Coating compositions based on derivatives of such polymers
    • C09D129/02—Homopolymers or copolymers of unsaturated alcohols
    • C09D129/04—Polyvinyl alcohol; Partially hydrolysed homopolymers or copolymers of esters of unsaturated alcohols with saturated carboxylic acids
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
    • C09D139/00—Coating compositions based on homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a single or double bond to nitrogen or by a heterocyclic ring containing nitrogen; Coating compositions based on derivatives of such polymers
    • C09D139/04—Homopolymers or copolymers of monomers containing heterocyclic rings having nitrogen as ring member
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
    • C09D7/00—Features of coating compositions, not provided for in group C09D5/00; Processes for incorporating ingredients in coating compositions
    • C09D7/40—Additives
    • C09D7/60—Additives non-macromolecular
    • C09D7/63—Additives non-macromolecular organic
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
    • H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
    • H01L21/02104—Forming layers
    • H01L21/02107—Forming insulating materials on a substrate
    • H01L21/02109—Forming insulating materials on a substrate characterised by the type of layer, e.g. type of material, porous/non-porous, pre-cursors, mixtures or laminates
    • H01L21/02112—Forming insulating materials on a substrate characterised by the type of layer, e.g. type of material, porous/non-porous, pre-cursors, mixtures or laminates characterised by the material of the layer
    • H01L21/02118—Forming insulating materials on a substrate characterised by the type of layer, e.g. type of material, porous/non-porous, pre-cursors, mixtures or laminates characterised by the material of the layer carbon based polymeric organic or inorganic material, e.g. polyimides, poly cyclobutene or PVC
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    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
    • H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
    • H01L21/02104—Forming layers
    • H01L21/02107—Forming insulating materials on a substrate
    • H01L21/02225—Forming insulating materials on a substrate characterised by the process for the formation of the insulating layer
    • H01L21/0226—Forming insulating materials on a substrate characterised by the process for the formation of the insulating layer formation by a deposition process
    • H01L21/02282—Forming insulating materials on a substrate characterised by the process for the formation of the insulating layer formation by a deposition process liquid deposition, e.g. spin-coating, sol-gel techniques, spray coating
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    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
    • H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
    • H01L21/04—Manufacture or treatment of semiconductor devices or of parts thereof the devices having potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer
    • H01L21/18—Manufacture or treatment of semiconductor devices or of parts thereof the devices having potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer the devices having semiconductor bodies comprising elements of Group IV of the Periodic Table or AIIIBV compounds with or without impurities, e.g. doping materials
    • H01L21/26—Bombardment with radiation
    • H01L21/263—Bombardment with radiation with high-energy radiation
    • H01L21/268—Bombardment with radiation with high-energy radiation using electromagnetic radiation, e.g. laser radiation
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    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
    • H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
    • H01L21/04—Manufacture or treatment of semiconductor devices or of parts thereof the devices having potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer
    • H01L21/18—Manufacture or treatment of semiconductor devices or of parts thereof the devices having potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer the devices having semiconductor bodies comprising elements of Group IV of the Periodic Table or AIIIBV compounds with or without impurities, e.g. doping materials
    • H01L21/30—Treatment of semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/26
    • H01L21/302—Treatment of semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/26 to change their surface-physical characteristics or shape, e.g. etching, polishing, cutting
    • H01L21/304—Mechanical treatment, e.g. grinding, polishing, cutting
    • H01L21/3043—Making grooves, e.g. cutting
    • H—ELECTRICITY
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    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
    • H01L21/67—Apparatus specially adapted for handling semiconductor or electric solid state devices during manufacture or treatment thereof; Apparatus specially adapted for handling wafers during manufacture or treatment of semiconductor or electric solid state devices or components ; Apparatus not specifically provided for elsewhere
    • H01L21/683—Apparatus specially adapted for handling semiconductor or electric solid state devices during manufacture or treatment thereof; Apparatus specially adapted for handling wafers during manufacture or treatment of semiconductor or electric solid state devices or components ; Apparatus not specifically provided for elsewhere for supporting or gripping
    • H01L21/6835—Apparatus specially adapted for handling semiconductor or electric solid state devices during manufacture or treatment thereof; Apparatus specially adapted for handling wafers during manufacture or treatment of semiconductor or electric solid state devices or components ; Apparatus not specifically provided for elsewhere for supporting or gripping using temporarily an auxiliary support
    • H01L21/6836—Wafer tapes, e.g. grinding or dicing support tapes
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2221/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof covered by H01L21/00
    • H01L2221/67—Apparatus for handling semiconductor or electric solid state devices during manufacture or treatment thereof; Apparatus for handling wafers during manufacture or treatment of semiconductor or electric solid state devices or components; Apparatus not specifically provided for elsewhere
    • H01L2221/683—Apparatus for handling semiconductor or electric solid state devices during manufacture or treatment thereof; Apparatus for handling wafers during manufacture or treatment of semiconductor or electric solid state devices or components; Apparatus not specifically provided for elsewhere for supporting or gripping
    • H01L2221/68304—Apparatus for handling semiconductor or electric solid state devices during manufacture or treatment thereof; Apparatus for handling wafers during manufacture or treatment of semiconductor or electric solid state devices or components; Apparatus not specifically provided for elsewhere for supporting or gripping using temporarily an auxiliary support
    • H01L2221/68354—Apparatus for handling semiconductor or electric solid state devices during manufacture or treatment thereof; Apparatus for handling wafers during manufacture or treatment of semiconductor or electric solid state devices or components; Apparatus not specifically provided for elsewhere for supporting or gripping using temporarily an auxiliary support used to support diced chips prior to mounting

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Abstract

The invention relates to a method for manufacturing a semiconductor chip and a protective film forming agent. Provided are a method for manufacturing a semiconductor chip by cutting a semiconductor wafer, and a protective film forming agent which can be used in the method for manufacturing a semiconductor chip, and which can form a processing groove in a protective film formed on the semiconductor wafer and the semiconductor wafer with high processing accuracy by laser irradiation. A method for manufacturing a semiconductor chip by cutting a semiconductor wafer, comprising: coating a protective film forming agent containing a water-soluble resin, a light absorbing agent and a solvent on a semiconductor wafer to form a protective film; and a processing groove for irradiating a predetermined position of 1 or more layers including a protective film on the semiconductor wafer with laser light including light having a wavelength of 515nm to form a pattern corresponding to the shape of the semiconductor wafer, wherein the protective film has an absorbance of 0.05 or more per 1 μm thickness at the wavelength of 515 nm.

Description

Method for manufacturing semiconductor chip and protective film forming agent
Technical Field
The invention relates to a method for manufacturing a semiconductor chip and a protective film forming agent.
Background
A wafer formed in a semiconductor device manufacturing process is obtained by dividing a laminated body in which an insulating film and a functional film are laminated on a surface of a semiconductor substrate such as silicon, into predetermined division lines in a grid pattern called streets (streets), and each region divided by the streets becomes a semiconductor chip such as an IC or an LSI.
A plurality of semiconductor chips can be obtained by cutting the wafer along the streets. In the optical device wafer, a multilayer body in which gallium nitride compound semiconductors and the like are stacked is divided into a plurality of regions by a track. By cutting along the track, the optical device wafer is divided into optical devices such as light emitting diodes and laser diodes. These optical devices have been widely used in electrical equipment.
Conventionally, such cutting of a wafer along a track is performed by a cutting device called a dicing saw (dicer). However, in this method, since the wafer having the laminated structure is a highly brittle material, when the wafer is cut into semiconductor chips or the like by a cutter (dicing blade), there is a problem that damage, chipping, or the like occurs, or an insulating film necessary as a circuit element formed on the chip surface is peeled off.
In order to eliminate such a problem, the following method for manufacturing a semiconductor chip is proposed: a method for manufacturing a semiconductor device includes the steps of applying a protective film forming agent containing a water-soluble resin, a light absorbing agent, and a solvent to the surface of a semiconductor wafer to form a protective film, irradiating the protective film with laser light to decompose and remove a part of the protective film, thereby exposing the surface of the semiconductor wafer to form a processing groove, and then cutting the semiconductor wafer by plasma etching to divide the semiconductor wafer into semiconductor chips (ICs) (see patent document 1).
Documents of the prior art
Patent document
Patent document 1: international publication No. 2020/100403
Patent document 2: japanese Kokai publication No. 2014-523112
Disclosure of Invention
Problems to be solved by the invention
According to the technique of patent document 1, an opening (a processing groove) having a desired shape can be formed at a desired position of the protective film by laser irradiation. By forming an opening (processing groove) having a desired shape at a desired position of the protective film, the semiconductor wafer can be cut to produce a semiconductor chip having a desired shape.
On the other hand, as a technique for dicing a semiconductor substrate, a technique described in patent document 2 is also known. That is, in the dicing method described in patent document 2, the following method is adopted: the mask is patterned using a laser having a wavelength of 530 nm or less and a laser pulse width of 500 femtoseconds or less.
Further, this method is considered to suppress chipping (chipping), micro-cracking, and peeling.
However, when a semiconductor chip is manufactured by the conventional technique disclosed in patent document 1 or the like, since a situation such as a situation where debris (hereinafter, referred to as "デブリ") from the semiconductor wafer or the protective film is accumulated in the vicinity of the opening of the protective film (for example, in the vicinity of the end of the processing groove) or the like occurs due to laser irradiation, it is sometimes difficult to form the processing groove formed in the protective film or the semiconductor wafer into a desired shape.
Therefore, it is desired to improve the processing accuracy by laser irradiation and to form a processing groove formed in the protective film and the semiconductor wafer into a desired shape.
The present invention has been made in view of the above-described problems, and an object thereof is to provide a method for manufacturing a semiconductor chip by cutting a semiconductor wafer, in which a processing groove can be formed in a protective film formed on the semiconductor wafer and the semiconductor wafer with high processing accuracy by laser irradiation, and a protective film forming agent that can be used in the method for manufacturing a semiconductor chip.
Means for solving the problems
The inventors of the present application have found that a method for manufacturing a semiconductor chip by cutting a semiconductor wafer includes: coating a protective film forming agent comprising a water-soluble resin (A), a light absorber (B) and a solvent (S) on a semiconductor wafer to form a protective film; and irradiating a predetermined position of 1 or more layers including the protective film on the semiconductor wafer with laser light including light having a wavelength of 515nm to form a processing groove having a pattern corresponding to the shape of the semiconductor chip with the surface of the semiconductor wafer exposed, and to set the absorbance of the protective film at a wavelength of 515nm per 1 μm thickness to 0.05 or more. More specifically, the present invention provides the following.
The 1 st aspect of the present invention is a method for manufacturing a semiconductor chip by cutting a semiconductor wafer, the method including the steps of:
coating a protective film forming agent comprising a water-soluble resin (A), a light absorbing agent (B) and a solvent (S) on a semiconductor wafer to form a protective film; and
irradiating a predetermined position of 1 or more layers including the protective film on the semiconductor wafer with laser light including light having a wavelength of 515nm to form a processing groove having a pattern corresponding to the shape of the semiconductor chip and exposing the surface of the semiconductor wafer,
wherein the protective film has an absorbance per 1 μm thickness at a wavelength of 515nm of 0.05 or more.
The invention of claim 2 is a protective film forming agent for forming a protective film on the surface of a semiconductor wafer during dicing of the semiconductor wafer,
which comprises a water-soluble resin (A), a light absorber (B), and a solvent (S),
the protective film has an absorbance per 1 μm thickness at a wavelength of 515nm of 0.05 or more.
A 3 rd aspect of the present invention is a method for manufacturing a semiconductor chip by cutting a semiconductor wafer, the method including the steps of:
coating a protective film forming agent comprising a water-soluble resin (A), a light absorbing agent (B) and a solvent (S) on a semiconductor wafer to form a protective film;
a processing groove for forming a pattern corresponding to the shape of the semiconductor chip, wherein the surface of the semiconductor wafer is exposed by irradiating a green laser beam to a predetermined position of 1 or more layers including the protective film on the semiconductor wafer; and
the protective film is removed and the protective film is removed,
wherein the protective film has an absorbance per 1 μm thickness at a wavelength of 515nm of 0.05 or more.
ADVANTAGEOUS EFFECTS OF INVENTION
According to the present invention, it is possible to provide a method for manufacturing a semiconductor chip by cutting a semiconductor wafer, which can form a processing groove in a protective film formed on the semiconductor wafer and the semiconductor wafer with high processing accuracy by laser irradiation, and a protective film forming agent that can be used in the method for manufacturing a semiconductor chip.
Drawings
Fig. 1 is a perspective view showing a semiconductor wafer processed by the method for manufacturing a semiconductor chip of the present invention.
FIG. 2 is an enlarged sectional view of the semiconductor wafer shown in FIG. 1.
FIG. 3 is an enlarged sectional view of a main portion of a semiconductor wafer having a protective film formed thereon.
Fig. 4 is a perspective view showing a state in which a semiconductor wafer having a protective film formed thereon is supported on a ring-shaped frame via a protective tape.
FIG. 5 is a perspective view of a main part of a laser processing apparatus for performing laser irradiation.
FIG. 6 is an enlarged cross-sectional view of a semiconductor wafer including a protective film and a processing groove formed by laser irradiation.
Fig. 7 is an explanatory view showing plasma irradiation to the semiconductor wafer shown in fig. 6.
Fig. 8 is an enlarged cross-sectional view showing a state where a semiconductor wafer is divided into semiconductor chips by plasma irradiation.
FIG. 9 is an enlarged sectional view showing a state where a protective film on a semiconductor chip has been removed.
Fig. 10 is a plan view illustrating a method of evaluating a machined groove (evaluating laser workability).
Description of the reference numerals
2: semiconductor wafer
20: substrate
21: laminated body
22: semiconductor chip
23: track path
24: protective film
25: laser processing tank
26: cutting groove
5: ring frame
6: protective adhesive tape
7: laser processing apparatus
71: chuck table of laser processing device
72: laser irradiation mechanism
Detailed Description
Method for manufacturing semiconductor chip and protective film forming agent
The method for manufacturing the semiconductor chip is performed by cutting the semiconductor wafer.
The method for manufacturing a semiconductor chip includes the steps of:
coating a protective film forming agent comprising a water-soluble resin (A), a light absorbing agent (B) and a solvent (S) on a semiconductor wafer to form a protective film; and
irradiating a predetermined position of 1 or more layers including the protective film on the semiconductor wafer with laser light or green laser light including light having a wavelength of 515nm to form a processing groove having a pattern corresponding to the shape of the semiconductor chip and exposing the surface of the semiconductor wafer,
wherein the protective film has an absorbance per 1 μm thickness at a wavelength of 515nm of 0.05 or more.
Hereinafter, the formation of the protective film is also referred to as a "protective film forming step", the formation of the processing groove is also referred to as a "processing groove forming step", and the cutting of the positions of the streets in the semiconductor wafer is also referred to as a "cutting step".
The steps in the method for manufacturing a semiconductor chip and the protective film forming agent usable in the method are specifically described below.
Protective film forming process
In the protective film forming step, a protective film forming agent is applied to the semiconductor wafer to form a protective film.
The shape of the processing surface of the semiconductor wafer is not particularly limited as long as the desired processing can be performed on the semiconductor wafer. Typically, the processing surface of a semiconductor wafer has a large number of irregularities. Further, a concave portion is formed in a region corresponding to the track.
In the processing surface of the semiconductor wafer, a plurality of regions corresponding to semiconductor chips are divided by streets.
The thickness of the protective film is typically preferably 0.1 μm to 100 μm, and more preferably 0.5 μm to 10 μm, depending on the size, performance, and the like of the semiconductor chip to be manufactured.
Hereinafter, a method for manufacturing a semiconductor chip by dicing (cutting) a semiconductor wafer including a plurality of semiconductor chips divided by grid-like streets, using a protective film forming agent, will be described as a preferred embodiment of a method for manufacturing a semiconductor chip, with reference to the drawings.
Fig. 1 is a perspective view of a semiconductor wafer to be processed. Fig. 2 is an enlarged cross-sectional view of a main portion of the semiconductor wafer shown in fig. 1. In the semiconductor wafer 2 shown in fig. 1 and 2, a laminated body 21 in which a functional film (which forms an insulating film and a circuit) is laminated is provided on a surface 20a of a semiconductor substrate 20 made of silicon or the like. In the stacked body 21, a plurality of semiconductor chips 22 such as ICs and LSIs are formed in a matrix.
Here, the shape and size of the semiconductor chip 22 are not particularly limited, and may be appropriately set according to the design of the semiconductor chip 22.
Each semiconductor chip 22 is divided by traces 23 formed in a lattice shape. In the illustrated embodiment, the insulating film used as the laminate 21 includes a Low dielectric constant insulator film (Low-k film) including: SiO 2 2 A film or an inorganic film such as SiOF or BSG (SiOB); organic films as polymer films such as polyimide-based and parylene-based polymer films.
The surface of the laminate 21 corresponds to the surface 2a as a processing surface. On the surface 2a, a protective film is formed using a protective film forming agent.
In the protective film forming step, a protective film is formed by applying a protective film forming agent to the front surface 2a of the semiconductor wafer 2 by, for example, a spin coater. The method of applying the protective film forming agent is not particularly limited as long as a protective film having a desired film thickness can be formed.
The protective film formed in the protective film forming step has an absorbance of 0.05 or more per 1 μm of thickness at a wavelength of 515 nm. By forming the protective film having such absorbance, the processing groove can be formed with high processing accuracy, and details will be described later.
The absorbance of the protective film per 1 μm thickness at a wavelength of 515nm is preferably 0.10 or more, more preferably 0.20 or more, and further preferably 0.40 or more.
The protective film preferably has an absorption maximum wavelength in a wavelength range of 495nm to 566nm inclusive. The maximum absorption wavelength refers to a wavelength showing the maximum absorbance in the absorption spectrum.
The protective film forming agent capable of forming a protective film in the protective film forming step contains a water-soluble resin (A), a light absorbing agent (B) and a solvent (S).
Hereinafter, essential or optional components contained in the protective film forming agent will be described. The absorbance of the protective film can be set to a desired value by adjusting the type and amount of each component contained in the protective film forming agent.
< Water-soluble resin (A) >)
The water-soluble resin (a) is a base material of a protective film formed using the protective film forming agent. The type of the water-soluble resin is not particularly limited as long as it is a resin that can be dissolved in a solvent such as water and applied and dried to form a film.
In the present specification, the term "water-solubility of the water-soluble resin (A)" means that 0.5g or more of a solute (water-soluble resin) is dissolved in 100g of water at 25 ℃.
Specific examples of the type of the water-soluble resin (a) include vinyl resins, cellulose resins, polyethylene oxide, polyglycerol, water-soluble nylon, and the like.
The vinyl resin is not particularly limited as long as it is a water-soluble resin which is a homopolymer or a copolymer of a monomer having a vinyl group. Examples of the vinyl resin include polyvinyl alcohol, polyvinyl acetal (including a vinyl acetate copolymer), polyvinyl pyrrolidone, polyacrylamide, poly (N-alkylacrylamide), polyallylamine, poly (N-alkylallylamine), partially amidated polyallylamine, poly (diallylamine), allylamine-diallylamine copolymer, polyacrylic acid, polyvinyl alcohol polyacrylic acid block copolymer, and polyvinyl alcohol polyacrylate block copolymer.
The cellulose resin is not particularly limited as long as it is a water-soluble cellulose derivative. Examples of the cellulose resin include methyl cellulose, ethyl cellulose, and hydroxypropyl cellulose.
These can be used alone in 1 kind, also can be combined with more than 2 kinds.
In the specific example of the water-soluble resin (a), from the viewpoint of preventing the shape of the processed tank from being deteriorated due to thermal collapse of the protective film, a vinyl resin and a cellulose resin are preferable, and polyvinylpyrrolidone, polyvinyl alcohol, and hydroxypropyl cellulose are more preferable.
The water-soluble resin (a) is preferably a resin that exhibits a weight loss rate of 70 wt% or more when heated to 500 ℃ in thermogravimetric measurement. The resin showing a weight loss rate of 70 wt% or more when heated to 500 ℃ in the thermal gravimetric measurement is a resin which mostly decomposes and disappears when heated to about 500 ℃. The weight loss rate at a temperature of 500 ℃ is more preferably 80% by mass or more, and still more preferably 90% by mass or more and 95% by mass or more.
In the case of using the protective film forming agent containing the water-soluble resin (a) having the weight loss rate at a temperature of up to 500 ℃ in the above range, the decomposition of the water-soluble resin (a) in the protective film based on the laser energy proceeds favorably, and therefore, the processed groove having a more favorable opening can be easily formed in the protective film by laser irradiation.
The water-soluble resin (a) preferably has a weight loss rate of 10 wt% or more, more preferably 15 wt% or more, when heated to 350 ℃.
In the case of using the water-soluble resin (a), at least the water-soluble resin (a) is easily decomposed by the energy given by the laser light, and even in the case of irradiating the laser light with low output, a processed groove which is more favorably opened in the protective film is easily formed.
The thermogravimetric measurement for determining the weight loss rate can be performed according to a usual thermogravimetric measurement method.
The method for adjusting the weight loss rate of the water-soluble resin (a) is not particularly limited. In general, in the case of the same type of resin, the smaller the average molecular weight, the higher the weight reduction rate of the water-soluble resin (A).
From the viewpoint of achieving both the degradability upon laser irradiation and the film-forming property, the weight average molecular weight of the water-soluble resin (a) is preferably 15,000 to 300,000, and more preferably 20,000 to 200,000.
The protective film formed on the surface of the semiconductor wafer is usually removed from the surface of the semiconductor wafer or the semiconductor chip by, for example, water washing at an appropriate time after the formation of the processing tank in accordance with the method of cutting the semiconductor wafer provided with the protective film and the processing tank into semiconductor chips. Therefore, from the viewpoint of water-washability of the protective film, a water-soluble resin having low affinity with the surface of the semiconductor wafer is preferable. The water-soluble resin having a low affinity with the surface of the semiconductor wafer is preferably a resin having only an ether bond, a hydroxyl group, and an amide bond as a polar group, and examples thereof include polyvinyl alcohol, polyethylene glycol, polyvinylpyrrolidone, and hydroxypropyl cellulose.
The ratio of the mass of the water-soluble resin (a) in the protective film forming agent to the total mass of the water-soluble resin (a) and the mass of the light absorber (B) is preferably 60 to 99 mass%, more preferably 80 to 95 mass%, in view of preventing the occurrence of an opening defect when the protective film is irradiated with laser light to form a processed groove, the shape of the processed groove being deteriorated due to thermal collapse of the protective film, and the like.
< light absorber (B) >
The protective film forming agent contains a light absorber (B) for the purpose of efficiently absorbing the energy of the laser light to promote the thermal decomposition of the protective film.
Further, the light absorber (B) contains an absorber having an absorbing ability for light having a wavelength of 515 nm.
As the absorbent having an absorbing ability for light having a wavelength of 515nm, an organic compound is preferable. Examples of the absorbent having an absorption ability for light having a wavelength of 515nm include a water-soluble dye, and a water-soluble ultraviolet absorber. They are all water-soluble, and are advantageous in terms of being uniformly present in the protective film. In addition, they exhibit high affinity for the surface of semiconductor wafers. Therefore, when a protective film forming agent containing these light absorbers (B) is used, a protective film having high adhesiveness to the surface of the semiconductor wafer can be easily formed.
When the water-soluble light absorbing agent (B) is used, the protective film forming agent has high storage stability, and the protective film forming agent does not cause problems such as phase separation of the protective film forming agent and sedimentation of the light absorbing agent (B) during storage, and therefore, it is advantageous in that the protective film forming agent can be easily maintained in good coatability for a long period of time.
A water-insoluble light absorbing agent such as a pigment may be used. When a water-insoluble light absorbing agent is used, although the use of a protective film forming agent is not seriously hindered, variation in the laser absorption capability of the protective film may occur, it is difficult to obtain a protective film forming agent having excellent storage stability and coatability, or it is difficult to form a protective film having a uniform thickness.
Specific examples of the absorbent (B) having an ability to absorb light having a wavelength of 515nm include basic Red 2, basic Red 5, rhodamine 6G, acid Red 1, acid Red 18, acid Red 27, acid Red 114, Azolorubin, and tetrabromofluorescein. The absorbent (B) preferably contains at least one selected from rhodamine, fluorescein and derivatives thereof, and particularly preferably contains rhodamine 6G and tetrabromofluorescein, from the viewpoints of high water solubility and excellent absorption ability of light having a wavelength of 515 nm.
In addition, the light absorber (B) is preferably a mother nucleus (chemical structure) having three or more aromatic rings conjugated with each other, from the viewpoint of easily improving the absorption ability of light at a wavelength of 515 nm.
The light absorber (B) may include: an absorbent having an absorption ability for light having a wavelength of 515 nm; and an absorbent having no absorption ability for light having a wavelength of 515 nm.
The ratio of the mass of the absorbent having an ability to absorb light having a wavelength of 515nm to the mass of the light absorber (B) is preferably 70% by mass or more, more preferably 80% by mass or more, still more preferably 95% by mass or more, and particularly preferably 100% by mass.
The ratio of the mass of the light absorbing agent (B) in the protective film forming agent to the total mass of the water-soluble resin (a) and the mass of the light absorbing agent (B) is preferably 1 mass% to 40 mass%, more preferably 5 mass% to 20 mass%, from the viewpoint that an opening defect when the protective film is irradiated with laser light to form a processed groove, a shape deterioration of the processed groove due to thermal collapse of the protective film, and the like are less likely to occur.
< basic Compound (C) >
The protective film forming agent may contain the basic compound (C) or may not contain the basic compound (C). As the basic compound (C), any of inorganic compounds and organic compounds can be used. As the basic compound (C), an organic compound is preferable.
Specific examples of the basic compound (C) include basic inorganic compounds such as sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, sodium silicate, sodium metasilicate, and ammonia, and basic organic compounds such as ethylamine, n-propylamine, monoethanolamine, diethylamine, di-n-propylamine, diethanolamine, triethylamine, methyldiethylamine, dimethylethanolamine, triethanolamine, tetramethylammonium hydroxide, tetraethylammonium hydroxide, pyrrole, piperidine, 1, 8-diazabicyclo [5,4,0] -7-undecene, and 1, 5-diazabicyclo [4,3,0] -5-nonane.
The amount of the basic compound (C) used is not particularly limited within a range not to impair the object of the present invention. The amount of the basic compound (C) used is preferably 1 mole or more, more preferably 1 mole or more and 20 moles or less, relative to 1 mole of the light absorbent (B). The lower limit of the amount of the basic compound (C) to be used may be 1.5 moles or more, 2 moles or more, and 3 moles or more based on 1 mole of the light absorbent (B). The upper limit of the amount of the basic compound (C) used may be 15 moles or less, 10 moles or less, and 5 moles or less with respect to the light absorbent (B).
< other additives >
The protective film forming agent may contain other compounding agents in addition to the water-soluble resin (a) and the light absorbing agent (B) as long as the object of the present invention is not impaired. Examples of the other compounding agents include preservatives, surfactants, and the like.
As preservatives, benzoic acid, butyl paraben, ethyl paraben, methyl paraben, propyl paraben, sodium benzoate, sodium propionate, benzalkonium chloride, benzethonium chloride, benzyl alcohol, cetylpyridinium chloride, chlorobutanol, phenol, phenylethyl alcohol, 2-phenoxyethanol, phenylmercuric nitrate, thimerosal, m-cresol, lauryl dimethyl amine oxide or combinations thereof may be used.
The preservative is preferably used not only from the viewpoint of corrosion prevention by the protective film forming agent but also from the viewpoint of reducing the load of waste liquid treatment after cleaning of the semiconductor wafer. In order to clean the semiconductor wafer, a large amount of cleaning water is generally used. However, in the process using the above-described protective film forming agent, there is a concern that the propagation of the undesired bacteria in the waste liquid may be caused by the water-soluble resin (a) contained in the protective film forming agent. Therefore, it is preferable that the waste liquid from the process using the aforementioned protective film forming agent is treated separately from the waste liquid from the process not using the protective film forming agent. However, when the protective film forming agent contains a preservative, the propagation of the undesired bacteria by the water-soluble resin (a) is suppressed, and therefore, the waste liquid from the process in which the protective film forming agent is used can be treated in the same manner as the waste liquid from the process in which the protective film forming agent is not used. Therefore, the load on the wastewater treatment process can be reduced.
The surfactant is used to improve, for example, defoaming property during production of the protective film forming agent, stability of the protective film forming agent, coatability of the protective film forming agent, and the like. In particular, a surfactant is preferably used from the viewpoint of defoaming property at the time of producing the protective film forming agent.
In general, the protective film is formed by spin coating a protective film forming agent. However, when the protective film is formed, unevenness due to bubbles may occur. In order to suppress the generation of such unevenness, an antifoaming agent such as a surfactant is preferably used.
As the surfactant, a water-soluble surfactant can be preferably used. As the surfactant, any of nonionic surfactants, cationic surfactants, anionic surfactants, and amphoteric surfactants can be used. The surfactant may be silicone based. From the viewpoint of cleaning properties, nonionic surfactants are preferred.
< solvent (S) >
The protective film-forming agent usually contains a solvent (S) in order to dissolve the water-soluble resin (a) and the light absorber (B). As the solvent (S), any of water, an organic solvent, and an aqueous solution of an organic solvent can be used. The solvent (S) is preferably water or an aqueous solution of an organic solvent, in view of low risk of ignition during use, low cost, and the like.
Examples of the organic solvent that can be contained in the protective film forming agent include methanol, ethanol, alkylene glycol monoalkyl ether acetate, and the like.
Examples of the alkylene glycol include ethylene glycol and propylene glycol. Examples of the alkylene glycol monoalkyl ether include ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, propylene glycol monomethyl ether, and propylene glycol monoethyl ether. Examples of the alkylene glycol monoalkyl ether acetate include ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, propylene glycol monomethyl ether acetate, and propylene glycol monoethyl ether acetate.
The protective film forming agent may contain 2 or more kinds of organic solvents in combination.
When the protective film forming agent contains water and an organic solvent as the solvent (S), the concentration of the organic solvent in the solvent (S) may be, for example, 50 mass% or less, 30 mass% or less, or 20 mass% or less.
The solid content concentration of the protective film forming agent is not particularly limited within a range not to hinder the object of the present invention. The solid content concentration is, for example, preferably 5 mass% to 60 mass%, more preferably 5 mass% to 50 mass%, and still more preferably 10 mass% to 40 mass%. In the present specification, the solid component means a component other than the solvent (S).
Next, the liquid protective film forming agent covering the surface 2a is dried as necessary. Thereby, as shown in fig. 3, the protective film 24 is formed on the front surface 2a of the semiconductor wafer 2.
After the protective film 24 is formed on the front surface 2a of the semiconductor wafer 2 in the above manner, as shown in fig. 4, the protective tape 6 attached to the ring frame 5 is attached to the back surface of the semiconductor wafer 2.
< working groove Forming Process >
In the process groove forming step, a predetermined position of 1 or more layers including the protective film 24 on the semiconductor wafer 2 is irradiated with laser light, and a process groove having a pattern corresponding to the shape of the semiconductor chip 22 and exposing the front surface 20a of the semiconductor substrate 20 is formed.
Specifically, the laser light passes through the protective film 24 and is irradiated to the surface 2a (the trace 23) on the semiconductor wafer 2. As shown in fig. 5, the laser irradiation is performed by using a laser irradiation mechanism 72.
In the present embodiment, the laser light to be irradiated is a laser light including light having a wavelength of 515nm, or a green laser light.
The laser is preferably a so-called femtosecond laser.
In the present specification, the femtosecond laser refers to an ultrashort pulse laser in which a pulse width of a pulse laser is 1 femtosecond (fs) to 300 femtoseconds (fs).
The green laser beam is a laser beam including a light beam having a wavelength of 500nm to 560nm, and examples thereof include a green laser beam (wavelength of 532nm), an shg (second Harmonic generation) laser beam (wavelength of 532nm corresponding to half of a fundamental wave (1064 nm)), and the like.
By irradiating the protective film 24 formed on the semiconductor wafer 2 with laser light including light having a wavelength of 515nm or green laser light, laser processing is performed on the protective film 24 and the semiconductor wafer 2, which has a short wavelength, a narrow pulse width, and a suppressed thermal influence. Further, as described above, since the protective film 24 has an absorbance per 1 μm thickness at the wavelength of 515nm as high as 0.05 or more, the laser light including the light having the wavelength of 515nm and the reflected light of the green laser light when reaching the substrate are absorbed, and a good processed shape is maintained.
Therefore, the processed groove 25 can be formed satisfactorily in the protective film 24 and the semiconductor wafer 2, and the chips from the semiconductor wafer 2 and the protective film 24 can be suppressed, so that the processed groove 25 can be formed with high accuracy in the protective film 24 and the semiconductor wafer 2. Therefore, the processing groove 25 formed in the protective film 24 and the semiconductor wafer 2 can be formed in a desired shape, and a semiconductor chip having a desired shape can be manufactured by a subsequent cutting process.
The laser irradiation in the processing groove forming step is performed under the following processing conditions, for example. The diameter of the light collecting spot is appropriately selected in consideration of the width of the processing tank 25.
Laser: laser or green laser including light having wavelength of 515nm
Pulse width: 100 to 300 femtoseconds
Repetition frequency: 50kHz or more and 400kHz or less
Output power: 0.1W to 10.0W inclusive
Processing and conveying speed: 1 mm/sec to 800 mm/sec
By performing the above-described working groove forming step, as shown in fig. 6, the working grooves 25 are formed along the streets 23 in the laminated body 21 including the streets 23 in the semiconductor wafer 2.
After the irradiation of the laser light is performed along the predetermined track 23 as described above, the semiconductor wafer 2 held on the chuck table 71 is indexed in the direction indicated by the arrow Y only by the interval of the track, and the irradiation of the laser light is performed again.
After the irradiation and the indexing movement of the laser light are performed in accordance with all the streets 23 extending in the predetermined direction as described above, the semiconductor wafer 2 held on the chuck table 71 is rotated by 90 degrees and the irradiation and the indexing movement of the laser light are performed along the respective streets 23 extending at right angles to the predetermined direction as described above. In the above manner, the processed grooves 25 can be formed along all the streets 23 formed by the stacked body 21 on the semiconductor wafer 2.
< cutting Process >
In the cutting step, the semiconductor wafer 2 having the processing tank 25 is cut at a position corresponding to the position of the track 23.
Examples of the cutting method include: a method of cutting the semiconductor wafer 2 provided with the protective film 24 or the semiconductor wafer 2 from which the protective film 24 has been peeled off by a cutter; a method of cutting the semiconductor wafer 2 by irradiating the semiconductor wafer 2 provided with the protective film 24 and the processing groove 25 with laser light or plasma.
When cutting is performed by a cutter, for example, the semiconductor wafer 2 is cut by the cutter along the position of the processing bath 25 while supplying pure water to the cutting portion.
When the laser beam is irradiated, the processing bath 25 is irradiated with the laser beam to cut the semiconductor wafer 2. The laser light irradiated in the cutting step may be the same as or different from the laser light irradiated in the processing tank forming step.
When plasma is irradiated, a part or the entire surface of the semiconductor wafer 2 provided with the protective film is irradiated with plasma so that the plasma is exposed to the surface of the processing bath 25.
When cutting is performed by plasma irradiation, as shown in fig. 7, plasma is irradiated to the semiconductor wafer 2 provided with the protective film 24 and the processing bath 25. In this way, as shown in fig. 8, the positions of the processing grooves 25 in the semiconductor wafer 2 are cut.
Specifically, as described above, the processing groove 25 is formed in the semiconductor wafer 2 covered with the protective film 24, and then the protective film 24 and the surface 20a of the semiconductor substrate 20 exposed from the processing groove 25 are subjected to plasma irradiation, whereby the semiconductor wafer 2 is cut in accordance with the shape of the semiconductor chip 22, and the semiconductor wafer 2 is divided into the semiconductor chips 22.
The plasma irradiation conditions are not particularly limited as long as the semiconductor wafer 2 can be cut satisfactorily at the position of the processing bath 25. The plasma irradiation conditions are appropriately set within the range of general conditions for plasma etching of a semiconductor substrate, taking into consideration the material of the semiconductor wafer 2, the type of plasma, and the like.
In the plasma irradiation, a gas for generating plasma is appropriately selected according to the material of the semiconductor wafer 2. Typically, SF is used in the generation of the plasma 6 A gas.
Alternatively, the supply C may be alternately performed according to a so-called BOSCH process 4 F 6 Or C 4 F 8 The semiconductor wafer 2 is cut by protecting the side wall with gas or the like and etching the semiconductor wafer 2 by plasma irradiation. According to the BOSCH process, etching can be performed with a high aspect ratio, and the semiconductor wafer 2 can be easily cut even when the semiconductor wafer 2 is thick.
Next, as shown in fig. 9, the protective film 24 covering the surface of the semiconductor chip 22 is removed. As described above, the protective film 24 is formed using the protective film forming agent containing the water-soluble resin (a), and therefore the protective film 24 can be washed away with water (or hot water).
The method for manufacturing semiconductor chips by dicing a semiconductor wafer according to the embodiment has been described above. The protective film forming agent and the method for manufacturing a semiconductor chip according to the present invention can be applied to various methods for manufacturing a semiconductor chip as long as the methods include the following steps: a protective film is formed on the surface of a semiconductor wafer, and a processing groove is formed at a position corresponding to a track on the surface of the semiconductor wafer having the protective film.
Examples
The present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.
< Water-soluble resin (A) >)
In the examples and comparative examples, hydroxypropyl cellulose (HPC-SSL (manufactured by japan sodak)), polyvinyl pyrrolidone (PITZCOL K-90 (manufactured by first industrial pharmaceutical company)), and polyvinyl alcohol (PVA-505C (KURARAY co., LTD)) were used as the water-soluble resin (a).
As a result of thermogravimetric measurement of each water-soluble resin (a) used in the following manner, the weight loss rate of hydroxypropylcellulose was 99% by weight when heated to 500 ℃ and 50% by weight when heated to 350 ℃, 70% by weight when heated to 500 ℃ and 25% by weight when heated to 350 ℃ were measured as the weight loss rate of polyvinylpyrrolidone, and 90% by weight when heated to 500 ℃ and 50% by weight when heated to 350 ℃ were measured as the weight loss rate of polyvinyl alcohol.
Thermogravimetry was carried out using a TG/DTA apparatus (differential thermal-thermogravimetry apparatus, Hitachi High-Tech Science, TG/DTA6200R) under the following conditions.
Measuring temperature: 40-500 deg.C
Temperature rise rate: 10 ℃/min
Atmosphere: air (flow 200 NmL/min)
< light absorber (B) >, a process for producing the same
In the examples and comparative examples, basic red 2, basic red 5, rhodamine 6G, acid red 1, acid red 18, acid red 27, acid red 114, azorubine, tetrabromofluorescein, and ferulic acid (all manufactured by tokyo chemical industries, ltd.) were used as the light absorbing agent (B).
< basic Compound (C) >)
In some examples, monoethanolamine is used as the basic compound (C).
< organic solvent >
In examples and comparative examples, a mixed solvent of ion-exchanged water and an organic solvent was used as the solvent (S). As the organic solvent in the solvent (S), Propylene Glycol Monomethyl Ether (PGME) was used.
[ examples 1 to 11 and comparative example 1]
The protective film forming agents of examples and comparative examples were obtained by uniformly dissolving the water-soluble resin (a) of the kind and part by mass shown in table 1, the light absorbing agent (B) of the kind and part by mass shown in table 1, and the basic compound (C) of the part by mass shown in table 1 in the solvent (S) so that the solid content concentration became 10 mass%.
[ measurement of absorbance of protective film per 1 μm film thickness at wavelength of 515nm ]
The obtained protective film forming agent was applied onto a transparent glass substrate by a spin coating method. After the coating, the coating film was dried at 70 ℃ for 5 minutes to form a protective film having a film thickness (thickness) shown in table 2.
The formed protective film was measured for transmittance using a spectrophotometer (MCPD-3000 (Otsuka electronics)). From the measurement result of the transmittance at the wavelength of 515nm, the absorbance of the protective film at the wavelength of 515nm per 1 μm of the film thickness was measured using the following formula. The results are set forth in Table 2.
Absorbance ═ Log 10 (transmittance/100)
Figure BDA0003500205000000171
As for the results of the above tests, as shown in Table 2, the absorbance per 1 μm thickness of the protective film formed using the protective film forming agent of the example at 515nm was as high as 0.05 or more. Therefore, the protective film of the example was provided on the semiconductor wafer, and the laser beam including the light having the wavelength of 515nm and the green laser beam were irradiated, whereby the laser beam near the end portion of the processing groove of the protective film was absorbed and scattering was suppressed, and thus the shape of the processing groove was satisfactory. In addition, the laser beam is reflected from the substrate to cause unexpected processing defects in the protective film near the processing groove, thereby suppressing the occurrence of delamination (delamination) in the protective film and the semiconductor wafer, and forming the processing groove with high processing accuracy.
[ evaluation of solubility in solvent of light absorbent (B) ]
In the protective film forming agents of examples 1 to 11 and comparative example 1, the light absorbent (B) was rapidly dissolved in examples 3, 9, 10 and 11.
[ evaluation of machined groove (evaluation of laser processability) ]
< formation of processing groove by laser irradiation >
The protective film-forming agents of examples 3 and 9 to 11 and comparative example 1 thus obtained were applied to an 8-inch silicon substrate by spin coating to form a protective film having a film thickness (thickness) shown in table 3.
The surface of the silicon substrate provided with the protective film on the protective film side was irradiated with laser light in a straight line under the following conditions to form a processed groove, and then washed with water (shower: 3 minutes) to remove the protective film.
< laser irradiation conditions >
Laser: peak wavelength 514.355nm (including femtosecond laser with wavelength 515 nm)
Frequency: 100kHz
Conveying speed: 100mm/sec
Number of processes (Pass number): 1 time of
Processing strength: 100 percent
The following processing strengths were set as 100%: the protective films formed using the protective film forming agent of example 3 and having the film thicknesses shown in table 3 had a processing strength under the condition that the silicon substrate was shaved by 2 μm in the laser irradiation direction at a frequency of 100kHz, a transport speed of 100mm/sec, and the number of processing times of 1.
In comparative example 1, the laser light to be irradiated was nanosecond laser light having a peak wavelength of 355 nm.
< evaluation >
As a result of observing the laser-irradiated portion of the silicon substrate from which the protective film was removed with an optical microscope (MX-50 manufactured by Olympus Corporation, magnification: 100 times), in comparative example 1, a large amount of debris adhered to the vicinity of the processing groove (the vicinity of both end portions in the width direction of the processing groove). On the other hand, in examples 3 and 9 to 11, chipping was significantly less than in comparative example 1.
As for the adhered debris, as shown in fig. 10 which is a plan view illustrating a method of evaluating a processed groove (evaluation of laser processability), when the silicon substrate 80 is viewed from the side irradiated with the laser light (the side on which the protective film is formed), the width of the processed groove 81 (processing width x) and the width of the debris 82 and the entire processed groove 81 (layered width y) are measured, and the difference y-x between the layered width y and the processing width x is obtained. The larger the adhesion of debris, the larger the value of y-x. The results are shown in Table 3.
From the above results, it was found that by providing a specific protective film formed using the protective film forming agent of the example on a substrate and irradiating laser light including light having a wavelength of 515nm or green laser light, a processed groove can be formed satisfactorily, chipping can be suppressed, and a processed groove can be formed with high accuracy. The reason why the debris is attached in a large amount and in a wide range in comparative example 1 is presumed that the protective film cannot absorb reflection of the laser light reaching the substrate, and the protective film is pushed up and peeled off (delaminated) from the substrate.
[ Table 1]
Figure BDA0003500205000000191
[ Table 2]
Figure BDA0003500205000000201
[ Table 3]
Figure BDA0003500205000000202

Claims (8)

1. A method for manufacturing a semiconductor chip by cutting a semiconductor wafer, the method comprising the steps of:
coating a protective film forming agent comprising a water-soluble resin (A), a light absorbing agent (B), and a solvent (S) on the semiconductor wafer to form a protective film; and
irradiating a predetermined position of 1 or more layers including the protective film on the semiconductor wafer with laser light including light having a wavelength of 515nm to form a processing groove having a pattern corresponding to the shape of a semiconductor chip, in which the surface of the semiconductor wafer is exposed,
wherein the protective film has an absorbance per 1 μm thickness at a wavelength of 515nm of 0.05 or more.
2. The method for manufacturing a semiconductor chip according to claim 1, wherein the light absorber (B) contains at least one selected from the group consisting of rhodamine, fluorescein, and derivatives thereof.
3. The method for manufacturing a semiconductor chip according to claim 1, wherein a weight loss rate at a temperature of 500 ℃ in thermogravimetric measurement of the water-soluble resin (A) is 70% by weight or more.
4. The method for manufacturing a semiconductor chip according to any one of claims 1 to 3, comprising a step of cutting the position of the processing groove in the semiconductor wafer with a cutter.
5. A protective film forming agent for forming a protective film on a surface of a semiconductor wafer in dicing the semiconductor wafer,
which comprises a water-soluble resin (A), a light absorber (B) and a solvent (S),
the protective film has an absorbance per 1 [ mu ] m thickness at a wavelength of 515nm of 0.05 or more.
6. The protective film forming agent according to claim 5, wherein the light absorber (B) contains at least one selected from rhodamine, fluorescein, and derivatives thereof.
7. The protective film forming agent according to claim 5 or 6, wherein a weight loss rate at a temperature of 500 ℃ in thermogravimetric measurement of the water-soluble resin (A) is 70% by weight or more.
8. A method for manufacturing a semiconductor chip by cutting a semiconductor wafer, the method comprising the steps of:
coating a protective film forming agent comprising a water-soluble resin (A), a light absorber (B) and a solvent (S) on the semiconductor wafer to form a protective film;
a processing groove for forming a pattern corresponding to the shape of a semiconductor chip, in which the surface of the semiconductor wafer is exposed, by irradiating a green laser beam to a predetermined position of 1 or more layers including the protective film on the semiconductor wafer; and
the protective film is removed and the protective film is removed,
wherein the protective film has an absorbance per 1 μm thickness at a wavelength of 515nm of 0.05 or more.
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