JP7488231B2 - Tape for semiconductor processing and method for manufacturing semiconductor chips - Google Patents

Description

The present invention relates to a tape for semiconductor processing and a method for manufacturing semiconductor chips.

In recent years, semiconductor chips have been rapidly becoming thinner and smaller. In particular, in the case of IC cards with built-in semiconductor IC chips, such as memory cards and smart cards, the thickness of the semiconductor chip is required to be 75 μm or less. In LED/LCD driving devices, chips are becoming smaller, and there are chips that are 0.5 mm x 0.5 mm or less. As the demand for these devices increases in the future, it is expected that the need for thinner and smaller semiconductor chips will further increase.
Conventionally, semiconductor chips have been manufactured by a method in which a semiconductor wafer is thinned to a predetermined thickness in a back grinding process, an etching process, or the like, and then chipped in a dicing process. In this dicing process, a blade cut method is generally used in which the semiconductor wafer is cut by a dicing blade. In this case, the cutting resistance of the blade acts directly on the semiconductor wafer during cutting, and this cutting resistance may cause minute chipping in the semiconductor chip. This chipping not only damages the appearance of the semiconductor chip, but may also damage the circuit pattern on the chip in some cases. In particular, the allowable chipping level for the above-mentioned thinned or small chipped semiconductor chips is becoming stricter, so the problem of chipping will become even more serious in the future. In addition, the blade cut method has a relatively large blade width (also called a street or scribe line), which means that the semiconductor wafer cannot be used efficiently.

The occurrence of the above-mentioned chipping is regarded as one of the important problems to be solved, and various techniques for preventing the occurrence of chipping have been investigated.
For example, a laser dicing method has been proposed in which a semiconductor wafer is cut by irradiating it with a laser, and a pre-dicing method has been proposed in which a half cut with a blade or modification with a laser is performed prior to a back-grinding process, and individualization is performed in parallel with the back-grinding process. In such a dicing method, it is known that thermal decomposition products of the semiconductor wafer (e.g., silicon residues) generated by laser irradiation remain or accumulate on the semiconductor wafer, resulting in defects. A sheet or the like has been proposed that protects the semiconductor wafer from heat caused by laser irradiation while suppressing the remaining or accumulation of such thermal decomposition products. For example, Patent Document 1 describes "a protective sheet for laser dicing, comprising a base sheet and, on the upper surface of the base sheet,""(A) a water-soluble polymer and (B) a crosslinking agent, the weight average molecular weight (Mw) of the water-soluble polymer (A) being 10,000 to 150,000," and "a protective layer formed by applying a protective film composition for laser dicing, the protective layer having a thickness of 100 to 5,000 nm." However, even with the above-mentioned dicing method, the semiconductor wafer must ultimately be physically split in order to be divided into individual pieces, and the occurrence of chipping cannot be effectively suppressed.

A plasma dicing method has also been proposed, in which a semiconductor wafer is cut by spraying plasma-converted fluorine gas. The plasma dicing method can effectively suppress the occurrence of chipping because the semiconductor wafer can be divided into individual pieces by irradiating the plasma with plasma. Moreover, the plasma dicing method has a great advantage in that it can form streets that are small in width and highly linear, making efficient use of the semiconductor wafer. For example, Patent Document 2 describes a protective sheet used in the plasma dicing method as "a film in which a surface protective tape and a water-soluble film are laminated via an ultraviolet-curable adhesive layer, the water-soluble film being formed by partial saponification of a water-soluble polymer, and being insoluble in water at room temperature but soluble in warm water at 60°C to 100°C."

Japanese Patent No. 6055494 JP 2010-165963 A

However, when applying the plasma dicing method, as in Patent Document 2, a mask member is required to protect portions of the semiconductor wafer other than the streets from plasma, in addition to the surface protection tape that is peeled off after the backgrinding process.
The mask member arranged on the semiconductor wafer is removed only in the cutting region (the portion located on the street) by the grooving process, so that the street of the semiconductor wafer can be irradiated (exposed) to plasma. Therefore, the mask member used in the plasma dicing method has streets (grooves) formed by laser grooving prior to plasma dicing. At this time, the mask member is required to have heat resistance that is not easily deformed by heat generated by laser irradiation. In addition, the mask member is given fluidity to increase adhesion to the semiconductor wafer, and is particularly prone to deformation over time. However, in the actual manufacture of semiconductor chips, due to unique circumstances such as ensuring the freedom of process design, each process may not be performed in a continuous manner, for example, the laser grooving process and the plasma etching process may not be performed consecutively. While being able to respond to such circumstances in actual manufacture, in order to perform the plasma dicing process as desired, it is desirable for the mask member to have a time-dependent deformation suppression characteristic that at least suppresses time-dependent deformation of the street. However, when a mask member is formed from a material having high heat resistance or high resistance to deformation over time in order to impart heat resistance and resistance to deformation over time (both properties are collectively referred to as "laser grooving properties") to the mask member, there is generally a trade-off problem in that the adhesion to the semiconductor wafer and, further, the removability by washing with water, which will be described later, are reduced.

In addition, the masking material used in the plasma dicing method must be removed after the dicing process is completed. For example, Patent Document 2 describes that by making the film soluble in hot water, the film can be removed by washing with hot water. However, the film described in Patent Document 2 requires a process of heating to 60 to 100°C when attaching the water-soluble film and during the process of removing the water-soluble film, which makes the work complicated.

The present invention aims to provide a semiconductor processing tape that can be removed by washing with non-heated water while achieving both laser grooving properties and wafer adhesion. The present invention also aims to provide a method for easily manufacturing semiconductor chips using the semiconductor processing tape.

The inventors of the present invention have conducted intensive research in light of the above problems, and as a result have found that by using a water-soluble film containing a polymer compound having a weight-average molecular weight of 200,000 or more and a curable compound containing an oxazine structure as a mask member for plasma dicing, and laminating and integrating it with a surface protection tape that protects the circuit surface of a semiconductor wafer in a back grinding process to produce a semiconductor processing tape, it is possible to achieve both laser grooving properties and wafer adhesion while enabling the water-soluble film to be washed away with non-heated water. In addition, it has been found that by using this semiconductor processing tape in a semiconductor chip manufacturing method that includes a laser grooving process and a plasma dicing process, semiconductor chips can be easily manufactured. The present invention was completed after further research based on these findings.

The above object of the present invention is achieved by the following means.
<1> A (uncured) tape for semiconductor processing, which is a laminate of a water-soluble film containing a polymer compound having a weight average molecular weight of 200,000 or more and a curable compound containing an oxazine structure, and a surface protection tape that protects the circuit surface of a semiconductor wafer.
<2> The tape for semiconductor processing described in <1>, wherein the curable compound containing an oxazine structure has a (meth)acryloyl group.
<3> The semiconductor processing tape according to <1> or <2>, wherein the water-soluble film has a gel fraction of 10% or less when immersed in 100 g of water at 30°C for 10 minutes after curing.
<4> The semiconductor processing tape according to any one of <1> to <3>, wherein the content of the curable compound having an oxazine structure in the water-soluble film is 100 to 300 parts by mass per 100 parts by mass of the polymer compound.
<5> A step (a) of grinding the back surface of a semiconductor wafer in which the water-soluble film in the semiconductor processing tape according to any one of <1> to <4> is laminated to the circuit surface of the semiconductor wafer under non-heating;
a step (FC) of irradiating the water-soluble film in the semiconductor processing tape from the surface protection tape side with radiation to harden the water-soluble film;
(b) supporting and fixing the semiconductor wafer to a dicing tape via a ring frame;
a step (c) of peeling a surface protection tape of the semiconductor processing tape from the cured water-soluble film to expose the water-soluble film;
a step (d) of irradiating the hardened water-soluble film with a laser along a region to be cut of the semiconductor wafer to form a groove;
a step (e) of subjecting the semiconductor wafer to a plasma treatment from the water-soluble film side cut in the step (d) to separate the semiconductor wafer;
(f) a step of washing the cut water-soluble film with non-heated water to dissolve and remove the film;
A method for manufacturing a semiconductor chip comprising the steps of:

The present invention can provide a semiconductor processing tape that can be removed by washing with non-heated water while achieving both laser grooving properties and wafer adhesion. The present invention can also provide a method for easily manufacturing semiconductor chips using the semiconductor processing tape.

FIG. 1 is a schematic longitudinal sectional view showing a preferred embodiment of the semiconductor processing tape of the present invention. FIG. 2 is a schematic vertical cross-sectional view for explaining the step (a) and the step (FC) in the method for producing a semiconductor chip of the present invention. FIG. 3 is a schematic vertical cross-sectional view illustrating steps (b) to (d) in the method for producing a semiconductor chip of the present invention. FIG. 4 is a schematic vertical cross-sectional view illustrating steps (e) and (f) and further the pick-up step in the method for producing a semiconductor chip of the present invention.

In the present invention, a numerical range expressed using "to" means a range including the numerical values before and after "to" as the lower and upper limits.
In the present invention, the term "(meth)acrylic" refers to either or both of acrylic and methacrylic. The same applies to (meth)acrylate.
In the present invention, the term "water-soluble film" has radiation curability, and unless otherwise specified, includes an "uncured water-soluble film" (sometimes called a water-soluble uncured film) containing a curable compound containing an oxazine structure, and a "cured water-soluble film" (sometimes called a water-soluble cured film) containing a cured product of a curable compound containing an oxazine structure by irradiation with radiation. Furthermore, in the present invention, the term "semiconductor processing tape" includes a semiconductor processing tape having a water-soluble uncured film as the water-soluble film (uncured semiconductor processing tape) and a semiconductor processing tape having a water-soluble cured film (cured semiconductor processing tape) unless otherwise specified. In the present invention, radiation means light rays such as ultraviolet rays, or ionizing radiation such as electron beams, and is preferably ultraviolet rays.

[Tape for semiconductor processing]
The semiconductor processing tape of the present invention is a laminated tape having a water-soluble film and a surface protection tape, and is suitably used in the manufacturing method of semiconductor chips, focusing on the water-soluble film, in step (d) (laser grooving step) and step (e) (plasma dicing step) described below. Therefore, the semiconductor processing tape of the present invention can also be called a semiconductor wafer processing tape.
The uncured tape for semiconductor processing is a tape having a layer structure in which a water-soluble uncured film containing a polymer compound having a weight average molecular weight of 200,000 or more and a curable compound containing an oxazine structure is laminated and integrated with a surface protection tape that protects the circuit surface of a semiconductor wafer. Since the uncured tape for semiconductor processing is an integrated surface protection tape and a water-soluble uncured film, when used in a method for manufacturing semiconductor chips, the surface protection tape and the water-soluble uncured film can be attached to the semiconductor wafer at once, thereby improving work efficiency. On the other hand, the cured tape for semiconductor processing is a tape having a layer structure in which a water-soluble cured film containing a polymer compound having a weight average molecular weight of 200,000 or more and a cured product of a curable compound containing an oxazine structure is laminated and integrated with a surface protection tape.
The semiconductor processing tape of the present invention may have the above-mentioned configuration, and other configurations are not particularly limited. For example, the water-soluble film and/or the surface protection tape may have a protective layer on the surface. In addition, the water-soluble film, the surface protection tape, and other films or layers may have a single layer structure or a multilayer structure of two or more layers.
A semiconductor processing tape 3, which is a preferred embodiment of the present invention, has a three-layer structure in which a surface protection tape 4 including a base film 4A and an adhesive layer 4B and a water-soluble film 5 are laminated in contact with each other via the adhesive layer 4B, as shown in FIG.

In the semiconductor processing tape of the present invention, the total thickness and the thickness of each layer are set appropriately depending on the application, etc. For example, the total thickness of the semiconductor processing tape (total thickness of each layer) can be 100 to 800 μm.

The semiconductor processing tape of the present invention is usually in the form of a long strip, but can also be in the form of a strip, sheet, string, or other suitable shape depending on the application, etc. The length and width of the semiconductor processing tape are set appropriately, and as an example, the length can be 20 m or more and the width can be 200 to 400 mm.
The semiconductor processing tape can be produced, for example, by preparing a water-soluble film and a surface protection tape, laminating them together, and adhering them with an adhesive layer.

The semiconductor processing tape of the present invention has the above-mentioned composition, and in the form of an uncured semiconductor processing tape, it exhibits water-washable removability, wafer adhesion, and heat resistance, and in the form of a cured semiconductor processing tape (a cured water-soluble film (a curable compound containing an oxazine structure)), it exhibits time-dependent deformation suppression properties while maintaining these properties.

In the semiconductor processing tape having the above layer structure, the peeling force (180° peeling force at 23 ° C.) between the water-soluble film and the surface protection tape (the adhesive layer if the surface protection tape has an adhesive layer) is set to such an extent that the adhesion is maintained and the surface protection tape does not peel off in the step (a) of grinding the back surface of the semiconductor wafer, and the surface protection tape can be easily peeled off from the water-soluble cured film before the step (d) of providing a groove in the water-soluble cured film. This peeling force is not uniquely determined, but from the viewpoint of the peelability of the surface protection tape from the water-soluble cured film, the upper limit is, for example, preferably 2 N/25 mm or less, more preferably 1 N/25 mm or less, and even more preferably 0.5 N/25 mm or less. On the other hand, from the viewpoint of the adhesion in the grinding step, the lower limit is, for example, preferably more than 0.1 N/25 mm, and more preferably 0.2 N/25 mm or more.
When the adhesive layer of the surface protection tape contains a radiation-curable adhesive, it is preferable that the adhesive layer before curing has a peel force that satisfies, for example, the above-mentioned lower limit and adheres firmly to the water-soluble uncured film, while the adhesive layer after curing has a peel force that satisfies, for example, the above-mentioned upper limit.
A water-soluble film having the above composition usually exhibits a peel strength of 0.1 N/25 mm against the adhesive layer of a surface protection tape, and this peel strength can be appropriately adjusted by changing the composition of the water-soluble film or the adhesive layer.
The peel strength is a value measured by the following measurement method. That is, the semiconductor processing tape of the present invention is cut to a width of 25 mm, and the maximum peel strength is measured when the water-soluble film and the surface protection tape (adhesive layer) are peeled off at 23°C, a peel angle of 180°, and a peel speed of 300 mm/min using Strograph VG1F (product name, manufactured by Toyo Seiki Co., Ltd.). The other conditions are in accordance with Japanese Industrial Standards (JIS) Z 0237:2009. The maximum peel strength (N/25 mm) thus obtained is the semiconductor processing tape peel strength (N/25 mm).

(Water-soluble film)
The water-soluble film is for forming a mask pattern used in the plasma treatment step in the semiconductor chip manufacturing method of the present invention, and is resistant to plasma using, for example, fluorine-based gas. This water-soluble film also exhibits water solubility. The water solubility of the water-soluble film may be such that it dissolves in non-heated water (usually pure water), for example, water below 60°C, preferably water below 40°C. The lower limit of the water temperature is not particularly limited, but it can usually be 15°C, preferably 20°C. This water solubility is specifically such that, in the water washing removability test in the examples, the water-soluble film dissolves in water and can be removed without leaving any adhesive residue. When a semiconductor processing tape having such a water-soluble film exhibiting water solubility is used in a semiconductor chip manufacturing method having a plasma dicing step, it can be easily removed after the dicing step is completed while maintaining the property of forming a predetermined mask and protecting the parts of the semiconductor wafer (circuit surface) other than the streets from plasma.

The water-soluble uncured film contains a polymeric compound having a weight-average molecular weight of 200,000 or more, and a curable compound containing an oxazine structure, and the water-soluble cured film contains a polymeric compound having a weight-average molecular weight of 200,000 or more, and a cured product of a curable compound containing an oxazine structure.
The polymer compound contained in the water-soluble film is usually a polymer, preferably a water-soluble polymer. The water solubility of the water-soluble polymer is not particularly limited as long as the water-soluble film can exhibit the above water solubility. The polymer compound is not particularly limited, but preferably, water-soluble polymers such as polyvinyl alcohol, polyethylene glycol, polyethylene oxide, polyvinylpyrrolidone, and poly(2-ethyl-2-oxazoline) can be used. Polyvinyl alcohol may be saponified depending on the water solubility required for the water-soluble film. The polymer as the polymer compound is usually used as a non-crosslinked product, and thus exhibits sufficient water solubility in non-heated water.
The weight average molecular weight of the polymer compound is 200,000 or more. By setting the weight average molecular weight of the polymer compound used in combination with the curable compound containing an oxazine structure or its cured product to 200,000 or more, the water-soluble film can be given laser grooving properties, wafer adhesion, and water-washing removability. The weight average molecular weight of the polymer compound is preferably 200,000 to 3,000,000, more preferably 300,000 to 2,000,000, and even more preferably 300,000 to 1,000,000, in terms of being able to achieve a good balance of laser grooving properties, wafer adhesion, and water-washing removability at a high level. The weight average molecular weight of the polymer compound is the value measured by the method described in the examples. When the polymer compound (polymer) is specified by the degree of polymerization, it can be, for example, 200 to 10,000, although it depends on the molecular weight of each component constituting the polymer compound.

The curable compound having an oxazine structure contained in the water-soluble uncured film is a compound that functions as a radiation curing agent, and preferably has an oxazine structure and a polycondensation site (functional group).
The oxazine structure includes not only a 6-membered heterocyclic structure containing one oxygen atom and one nitrogen atom and having two unsaturated bonds, but also a 6-membered heterocyclic structure in which one or two of the unsaturated bonds have been reduced. Specifically, examples of the 6-membered heterocyclic structure having two unsaturated bonds include 1,2-oxazine, 1,3-oxazine, and 1,4-oxazine, and examples of the reduced 6-membered heterocyclic structure include dihydro- or tetrahydro-1,2-oxazine, dihydro- or tetrahydro-1,3-oxazine, and dihydro- or tetrahydro-1,4-oxazine. The oxazine structure is preferably a 6-membered saturated heterocyclic structure containing one oxygen atom and one nitrogen atom (tetrahydrooxazine), and more preferably tetrahydro-1,4-oxazine (morpholine).

The polycondensation site is preferably a polymerizable or condensable site (polymerizable functional group or condensable functional group), and is preferably a polymerizable functional group. Preferred examples of the polymerizable functional group include an ethylenically unsaturated bond and an epoxy group, and examples thereof include a vinyl group, an allyl group, a (meth)acryloyl group, a (meth)acryloyloxy group, a (meth)acryloylamino group, and a glycidyl group. Among these, a (meth)acryloyl group is preferred.
The oxazine structure and the polycondensation site are bonded directly or via a linking group. The bonding position of the oxazine structure is not particularly limited, but is preferably a nitrogen atom. The linking group is not particularly limited, and examples thereof include an alkylene group (preferably having 1 to 12 carbon atoms), an alkenylene group (preferably having 2 to 6 carbon atoms), an arylene group (preferably having 6 to 24 carbon atoms), an oxygen atom, a sulfur atom, a -NR ^N - group (R ^N represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or an aryl group having 6 to 10 carbon atoms), a carbonyl group, or a group combining these.

As the curable compound containing an oxazine structure, a compound having an oxazine structure, a polycondensation site, and an appropriate linking group can be used. A polymerizable compound having an oxazine structure is preferred, a polymerizable compound having an oxazine structure and a (meth)acryloyl group is more preferred, and (meth)acryloylmorpholine is even more preferred.
The curable compound containing an oxazine structure may have a substituent at any one of the oxazine structure, the polycondensation site, and the linking group.

The cured product of the curable compound containing an oxazine structure contained in the water-soluble cured film may be a compound (usually a polymer) obtained by curing the curable compound containing an oxazine structure, and forms an appropriate cured product depending on the polycondensation site. Specifically, it may be a cured product (polymer) obtained by a polymerization reaction or a cured product (condensate) obtained by a condensation reaction.

The content of the polymeric compound and the polymerizable compound having an oxazine structure or its cured product in the water-soluble film is not particularly limited and is appropriately determined. For example, the total content of the polymeric compound and the polymerizable compound having an oxazine structure or its cured product in the water-soluble film is preferably 40 to 100 mass%, more preferably 60 to 95 mass%. The content of the polymerizable compound having an oxazine structure or its cured product is preferably 100 to 300 mass parts per 100 mass parts of the polymeric compound. When the content of the polymerizable compound having an oxazine structure or its cured product is 300 parts by mass or less, the adhesion to the semiconductor wafer is strong, and peeling of the water-soluble film can be effectively suppressed in the step (a) of grinding the back surface of the semiconductor wafer and the step (d) of providing a groove. In addition, it exhibits high heat resistance. On the other hand, when it is 100 parts by mass or more, it exhibits time-dependent deformation suppression properties, and in the step (d) of providing a groove, deformation of the water-soluble film can be effectively suppressed over time. In order to achieve a good balance between high levels of laser grooving properties, wafer adhesion, and water-washing removability, it is more preferable that the content of the polymerizable compound having an oxazine structure or its cured product is 150 to 250 parts by mass.

It is preferable that the water-soluble film contains, in addition to the polymer compound and the polymerizable compound having an oxazine structure or a cured product thereof, a low molecular weight compound having a molecular weight of 800 or less, since this can further enhance wafer adhesion while maintaining the laser grooving properties and removability by water washing.
The low molecular weight compound is preferably a low molecular weight polymer, more preferably a water-soluble low molecular weight polymer. The water solubility of the water-soluble low molecular weight polymer is not particularly limited as long as the water-soluble film can exhibit the above water solubility. The low molecular weight compound is not particularly limited, but preferably polyvinyl alcohol and polyethylene glycol can be used. In terms of water solubility, the low molecular weight compound is preferably a compound that does not undergo a chemical reaction such as a crosslinking reaction with the polymer compound.
The molecular weight of the low molecular weight compound (weight average molecular weight in the case of a polymer) is 800 or less. By setting the molecular weight of the low molecular weight compound used in combination with the polymer compound and the polymerizable compound having an oxazine structure or its cured product to 800 or less, the water-soluble film can have laser grooving properties, wafer adhesion, and water-rinsing removability at a higher level. The molecular weight of the low molecular weight compound is preferably 100 to 800, more preferably 200 to 800, even more preferably 200 to 600, and particularly preferably 450 to 600. The weight average molecular weight of the low molecular weight compound (polymer) is a value measured by the same method as the weight average molecular weight of the polymer compound. In addition, when the low molecular weight compound (polymer) is specified by the degree of polymerization, it can be, for example, 5 to 20, although it depends on the molecular weight of each component constituting the low molecular weight compound.

When the water-soluble film contains a low molecular weight compound, the content is not particularly limited and is determined appropriately. For example, the total content of the polymer compound, the polymerizable compound having an oxazine structure or its cured product, and the low molecular weight compound in the water-soluble film is preferably 60 to 100 mass%, more preferably 80 to 100 mass%. The content of the low molecular weight compound is preferably 10 to 100 mass parts, more preferably 20 to 50 mass parts, per 100 mass parts of the polymer compound. If the content of the low molecular weight compound is 10 parts by mass or more, the adhesion to the semiconductor wafer is strong, and peeling of the water-soluble film can be effectively suppressed in the step (a) of grinding the back surface of the semiconductor wafer and the step (d) of providing a groove. On the other hand, if the content is 100 parts by mass or less, deformation of the water-soluble film can be effectively suppressed in the step (d) of providing a groove, and the linearity of the area to be cut can be improved in the subsequent step (e) of dividing into individual pieces.

The water-soluble film may contain a compound that does not fall under any of the categories of polymer compounds, polymerizable compounds having an oxazine structure or their cured products, and low molecular compounds, such as ultraviolet absorbers, radical initiators, surfactants, labeling materials, and silane coupling agents.
The ultraviolet absorber and the radical initiator can be any known one without any particular limitation. The content of the ultraviolet absorber and the content of the radical initiator in the water-soluble film are appropriately determined according to the content of the polymerizable compound having an oxazine structure and the absorbance of the water-soluble film, and can be, for example, 0.5 to 15% by mass, and preferably 1 to 13% by mass, based on 100 parts by mass of the polymer compound.

The water-soluble cured film preferably has a gel fraction of 10% or less when stirred in 100 g of water at 30°C for 10 minutes (300 rpm). If the gel fraction of the water-soluble cured film is 10% or less, the removability by washing with water is improved, and the water-soluble film remaining in a swollen state or adhesive residue in step (f) can be effectively reduced. In terms of further improving the removability by washing with water, the gel fraction of the water-soluble cured film is more preferably 8% or less, and even more preferably 5% or less. The gel fraction of the water-soluble cured film is the value measured using the method and conditions described in the examples.

The absorbance of the water-soluble film to electromagnetic waves with a wavelength of 355 nm is not particularly limited, but the absorbance of the water-soluble cured film is preferably 30% or more, more preferably 50% or more, in terms of excellent groove forming ability by laser irradiation. The absorbance of the water-soluble film can be appropriately adjusted by a known ultraviolet absorber and its content. Examples of the ultraviolet absorber include benzophenone, benzotriazole, and hydroxyphenyltriazine, and benzotriazole and hydroxyphenyltriazine are preferred from the viewpoint of energy absorption efficiency. In the present invention, the electromagnetic wave refers to electromagnetic waves among the radiation described below, and includes, for example, infrared rays, visible light, ultraviolet rays, X-rays (X-rays), and gamma rays (γ-rays).
The absorbance is a value measured by the following measurement method. That is, for a water-soluble cured film formed on a PET film (thickness 38 μm), the absorbance is measured in the wavelength range of 300 to 1000 nm using a spectrophotometer U-5100 (manufactured by Yamato Scientific Co., Ltd.) with the PET film as a reference. The absorbance at a wavelength of 355 nm is determined and regarded as the absorbance of the water-soluble film.

The thickness of the water-soluble film is not particularly limited, and is appropriately determined taking into consideration the removability by water washing, the conditions of step (f), the laser grooving characteristics, and further the suppression of the occurrence of edge dissolution (seepage) in step (a) of grinding the back surface. For example, it can be 1 to 100 μm, and is preferably 20 μm or less, more preferably 5 to 20 μm, and even more preferably 5 to 10 μm, in terms of excellent suppression of the occurrence of seepage while maintaining the removability by water washing and the laser grooving characteristics.

(Surface protection tape)
The surface protection tape may be any tape that is commonly used in the manufacturing method of semiconductor chips, without any particular limitation. The surface protection tape has a function of protecting the circuit surface of the semiconductor wafer in the manufacturing method of semiconductor chips, particularly in the back grinding step.
The surface protection tape used in the present invention has at least a base film and an adhesive layer on the surface of the base film. In the present invention, a preferred surface protection tape 4 has a two-layer structure having an adhesive layer 4B on the surface of a base film 4A, as shown in FIG. 1. In addition to the base film and the adhesive layer, a protective layer or the like may be present. The base film and the adhesive layer may each have a single layer structure or a multi-layer structure of two or more layers. The total thickness of the surface protection tape 4 (total thickness of each layer) is not particularly limited and can be, for example, 100 to 800 μm.

The material for forming the base film is not particularly limited, and examples of the material that is preferably used include polyolefin resins such as homopolymers or copolymers of α-olefins, such as polyethylene, polypropylene, ethylene-vinyl acetate copolymer, ethylene-acrylic acid copolymer, and ionomer, or mixtures thereof; engineering plastics, such as polyethylene terephthalate, polycarbonate, and polymethyl methacrylate; and thermoplastic elastomers, such as polyurethane, styrene-ethylene-butene-styrene, and pentene copolymers.
The substrate film can be produced by a general extrusion method. When various resins are laminated, a co-extrusion method, a lamination method, or the like can be applied. In this case, an adhesive layer may be provided between the resins, as is commonly done in the production method of ordinary laminate films. The thickness of the substrate film is preferably 30 to 200 μm from the viewpoints of strength/elongation properties and radiation transparency.

The adhesive layer may be any layer containing an adhesive, and may be formed, for example, using an adhesive composition. The adhesive composition is not particularly limited, and may be a composition containing an ordinary adhesive such as (meth)acrylic, rubber, or silicone. In terms of weather resistance, cost, etc., a (meth)acrylic adhesive is preferably used.
The (meth)acrylic adhesive may be a composition containing a copolymer having a (meth)acrylic acid ester as a constituent component (hereinafter referred to as "(meth)acrylic acid ester copolymer") as an adhesive component. This composition may contain a curing agent, which will be described later, in addition to the (meth)acrylic acid ester copolymer.

Examples of (meth)acrylic acid esters that are components of the (meth)acrylic acid ester copolymer include alkyl acrylates or alkyl methacrylates having a straight-chain or branched alkyl group having 30 or less carbon atoms, preferably 4 to 18 carbon atoms, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, t-butyl, isobutyl, amyl, isoamyl, hexyl, heptyl, cyclohexyl, 2-ethylhexyl, octyl, isooctyl, nonyl, isononyl, decyl, isodecyl, undecyl, lauryl, tridecyl, tetradecyl, stearyl, octadecyl, and dodecyl. The (meth)acrylic acid esters may be used alone or in combination of two or more kinds.
In the components constituting the (meth)acrylic acid ester copolymer, the content of the (meth)acrylic acid ester component is preferably 80% by mass or more, more preferably 90% by mass or more, and even more preferably 95 to 99.9% by mass.

The (meth)acrylic acid ester copolymer may contain components other than the (meth)acrylic acid ester (also referred to as other components). Examples of other components include carboxyl group-containing monomers such as (meth)acrylic acid, carboxyethyl (meth)acrylate, carboxypentyl (meth)acrylate, itaconic acid, maleic acid, fumaric acid, and crotonic acid, acid anhydride monomers such as maleic anhydride and itaconic anhydride, hydroxyl group-containing monomers such as hydroxyalkyl (meth)acrylate (preferably, the alkyl group of the (meth)acrylic acid ester is substituted with a hydroxy group), styrene sulfonic acid, allyl sulfonic acid, 2-(meth)acrylamide-2-methylpropanesulfonic acid, (meth) Examples of the monomers include sulfonic acid group-containing monomers such as acrylamidopropanesulfonic acid, sulfopropyl (meth)acrylate, and (meth)acryloyloxynaphthalenesulfonic acid, phosphoric acid group-containing monomers such as 2-hydroxyethyl acryloyl phosphate, (meth)acrylamide, (meth)acrylic acid N-hydroxymethylamide, (meth)acrylic acid alkylaminoalkyl esters (e.g., dimethylaminoethyl methacrylate, t-butylaminoethyl methacrylate, etc.), N-vinylpyrrolidone, acryloylmorpholine, vinyl acetate, styrene, and acrylonitrile. These components may be used alone or in combination of two or more.

In the solid components of the adhesive layer, the content of the (meth)acrylic acid ester copolymer (converted into the content in the state before reaction with the curing agent or photopolymerizable compound described below) is preferably 80% by mass or more, more preferably 90% by mass or more, and even more preferably 95 to 99.9% by mass.

The curing agent that may be contained in the (meth)acrylic adhesive is not particularly limited, and for example, the curing agents described in JP 2007-146104 A can be used. For example, epoxy compounds having two or more epoxy groups in the molecule such as 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane, 1,3-bis(N,N-diglycidylaminomethyl)toluene, 1,3-bis(N,N-diglycidylaminomethyl)benzene, N,N,N,N'-tetraglycidyl-m-xylylenediamine, 2,4-tolylenediisocyanate, 2,6-tolylenediisocyanate, 1,3-xylylenediisocyanate, 1,4-xylylenediisocyanate, and diphenylmethane-4,4'-diisocyanate and other isocyanate compounds having two or more isocyanate groups in the molecule; and aziridine compounds having two or more aziridinyl groups in the molecule, such as tetramethylol-tri-β-aziridinyl propionate, trimethylol-tri-β-aziridinyl propionate, trimethylolpropane-tri-β-aziridinyl propionate, and trimethylolpropane-tri-β-(2-methylaziridine)propionate.
The content of the curing agent may be adjusted according to the desired adhesive strength, and is preferably 0.01 to 10 parts by mass, and more preferably 0.1 to 5 parts by mass, per 100 parts by mass of the (meth)acrylic acid ester copolymer.

The (meth)acrylic adhesive may be a radiation-curable adhesive containing a photopolymerizable compound and a photopolymerization initiator in addition to the above adhesive component. By containing an adhesive component, a photopolymerizable compound, and a photopolymerization initiator, the adhesive layer can be cured by irradiation with radiation (preferably ultraviolet light), thereby reducing the adhesive strength of the adhesive layer. As such a photopolymerizable compound, for example, low molecular weight compounds having at least two or more photopolymerizable carbon-carbon double bonds in the molecule that can be three-dimensionally reticulated by irradiation with light, or oligomers obtained by polymerizing them, as described in JP-A-60-196956 and JP-A-60-223139, can be used.
The photopolymerizable compound is not particularly limited, and examples thereof include trimethylolpropane tri(meth)acrylate, pentaerythritol di(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol monohydroxypenta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, neopentyl glycol di(meth)acrylate, 1,4-butylene glycol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, (poly)ethylene glycol di(meth)acrylate, (poly)propylene glycol di(meth)acrylate, epoxy (meth)acrylate ((meth)acrylic acid adduct of epoxy compound), polyester (meth)acrylate ((meth)acrylic acid adduct of polyester), and urethane (meth)acrylate ((meth)acrylic acid adduct of urethane).
The photopolymerization initiator is not particularly limited, and for example, the photopolymerization initiators described in JP-A-2007-146104 or JP-A-2004-186429 can be used. Specifically, isopropyl benzoin ether, isobutyl benzoin ether, benzophenone, Michler's ketone, chlorothioxanthone, benzyl methyl ketal, α-hydroxycyclohexyl phenyl ketone, 2-hydroxymethylphenylpropane, etc. can be used.

As the radiation-curable pressure-sensitive adhesive, in addition to the combination of the above-mentioned (meth)acrylic acid ester copolymer and a low molecular weight compound having at least two radiation-polymerizable carbon-carbon double bonds in the molecule, it is also preferable to use a (meth)acrylic copolymer which is a copolymer having a (meth)acrylic acid ester as a constituent component and in which the repeating unit constituting this copolymer has a radiation-polymerizable carbon-carbon double bond (hereinafter referred to as a "radiation-polymerizable (meth)acrylic copolymer").
A radiation-polymerizable (meth)acrylic copolymer is a copolymer having reactive groups in the copolymer molecule that can undergo a polymerization reaction when irradiated with radiation, particularly ultraviolet light. Such reactive groups are ethylenically unsaturated groups, i.e., groups having a carbon-carbon double bond (ethylenically unsaturated bond), and examples of such groups include vinyl groups, allyl groups, styryl groups, (meth)acryloyloxy groups, and (meth)acryloylamino groups.
The radiation-polymerizable (meth)acrylic copolymer is not particularly limited, and examples thereof include (meth)acrylic copolymers obtained by reacting a (meth)acrylic copolymer having a functional group a with a compound having a functional group b reactive with the functional group a and a radiation-polymerizable carbon-carbon double bond (hereinafter referred to as a "radiation-polymerizable compound having functional group b"). Examples of the (meth)acrylic copolymer having a carbon-carbon double bond include the same materials as those described in paragraphs [0036] to [0055] of JP2014-192204A.

In the radiation-polymerizable compound having the functional group b, examples of the functional group b include a carboxyl group, a hydroxyl group, an amino group, a cyclic acid anhydride group, an epoxy group, and an isocyanate group. Specific examples of the radiation-polymerizable compound having the functional group b include acrylic acid, methacrylic acid, cinnamic acid, itaconic acid, fumaric acid, phthalic acid, 2-hydroxyalkyl acrylates, 2-hydroxyalkyl methacrylates, glycol monoacrylates, glycol monomethacrylates, N-methylol acrylamide, N-methylol methacrylamide, allyl alcohol, N-alkylaminoethyl acrylates, N-alkylaminoethyl methacrylates, acrylamides, methacrylamides, maleic anhydride, itaconic anhydride, fumaric anhydride, phthalic anhydride, glycidyl acrylate, glycidyl methacrylate, allyl glycidyl ether, and polyisocyanate compounds in which a portion of the isocyanate groups has been urethanized with a monomer having a hydroxyl group or a carboxyl group and a radiation-polymerizable carbon-carbon double bond.
In the reaction between the (meth)acrylic copolymer having the above functional group a and the radiation-polymerizable compound having the above functional group b, the acid value, hydroxyl value, etc. can be appropriately set by leaving unreacted functional groups.

The radiation-polymerizable (meth)acrylic copolymer can be obtained by solution polymerization in various solvents. As the organic solvent for solution polymerization, ketones, esters, alcohols, and aromatics can be used. In general, it is preferable to use a solvent that is a good solvent for acrylic polymers and has a boiling point of 60 to 120°C. For example, toluene, ethyl acetate, isopropyl alcohol, benzene, methyl cellosolve, ethyl cellosolve, acetone, methyl ethyl ketone, etc. can be used. As the polymerization initiator, radical generators such as azobis-based agents such as α,α'-azobisisobutylnitrile and organic peroxide-based agents such as benzoyl peroxide can be used. In this case, a catalyst and a polymerization inhibitor can be used in combination as necessary, and a copolymer with a desired molecular weight can be obtained by adjusting the polymerization temperature and polymerization time. The synthesis method is not limited to solution polymerization, and other methods such as bulk polymerization and suspension polymerization can also be used.

In addition, the adhesive composition constituting the adhesive layer 3 may contain a release agent, a tackifier, an adhesive adjuster, a surfactant, or other modifiers, as appropriate. It may also contain an inorganic compound filler.

The adhesive layer can be formed by applying the adhesive composition to a substrate such as a release film, drying it, and then transferring it to the surface of the substrate film.

There are no particular limitations on the thickness of the adhesive layer, so long as it does not interfere with adhesion to the water-soluble film and does not cause infiltration of dust or grinding water during grinding, but a thickness of 5 to 100 μm is usually appropriate.

[Method of manufacturing semiconductor chip]
Next, the method for producing a semiconductor chip of the present invention (hereinafter, sometimes simply referred to as the production method of the present invention) has the following steps, and a semiconductor chip can be simply produced by subjecting a semiconductor wafer to the treatment of each step. Therefore, the method for producing a semiconductor chip of the present invention can also be said to be a method for treating a semiconductor wafer.
The manufacturing method of the present invention is a method of sequentially carrying out the following steps (a) to (f) in the stated order, and other steps employed in manufacturing semiconductor chips may be appropriately carried out before step (a), between each step, or after step (f).
In the present invention, the step (FC) is carried out before the step (b) in consideration of handling, manufacturing workability, etc., but it can also be carried out after the step (b), i.e., after fixing to the dicing tape.

Step (a): The water-soluble film of the semiconductor processing tape of the present invention is applied to the circuit of a semiconductor wafer.
A step of grinding the back surface of a semiconductor wafer bonded to a surface of the semiconductor processing tape without heating. Step (FC): A water-soluble film of the semiconductor processing tape is irradiated from the surface protection tape side.
Step (b): The semiconductor wafer obtained in step (FC) is diced through a ring frame.
Step (c): A step of supporting and fixing the surface protection tape in the semiconductor processing tape to the water-soluble film (water
Step (d): Irradiating the water-soluble cured film with a laser along the intended cutting region of the semiconductor wafer.
Step (e): The semiconductor wafer is cut from the side of the cut water-soluble cured film by plasma.
Step (f): A step of washing the cut water-soluble cured film with non-heated water to dissolve and remove the film.

The semiconductor wafer used in the manufacturing method of the present invention is a wafer having a circuit surface (also called a pattern surface) on one side of which a circuit or the like of a semiconductor element is formed, and examples of such a wafer include a silicon wafer, a SiC wafer, a GaAs wafer, and a GaN wafer.
In the present invention, the circuit side refers to the side of the semiconductor wafer on which a pattern such as a circuit of a semiconductor element is formed, and the back side refers to the side opposite to the circuit side on which no circuit is formed (non-circuit side). This circuit side has lattice-like streets in a plan view. Here, the streets refer to the cutting lines of the semiconductor wafer.

In the manufacturing method of the present invention, with respect to the processes other than those related to the semiconductor processing tape of the present invention, processes in a normal semiconductor chip manufacturing method can be applied without any particular limitations.
The equipment and materials used in the manufacturing method of the present invention can be any equipment and materials that have been conventionally used for processing or treating semiconductor wafers, without any particular limitations, and the operating conditions of the equipment can be set appropriately.

The manufacturing method of the present invention will be specifically described with reference to the drawings, focusing on the processing related to the semiconductor processing tape of the present invention. Note that in the following description and drawings, the same or corresponding elements are given the same reference numerals, and duplicate explanations will be omitted. Figures 2 to 4 are schematic vertical cross-sectional views (cross-sectional views cut in the thickness direction along the diameter direction of the semiconductor wafer) showing a preferred embodiment of the manufacturing method of the present invention.

In the manufacturing method of the present invention, prior to step (a), as shown in Fig. 2 (a-1), the semiconductor processing tape 3 of the present invention (uncured tape for semiconductor processing) is laminated with the semiconductor wafer 1 so that the water-soluble uncured film 5 of the semiconductor processing tape 3 of the present invention contacts the circuit surface 1A of the semiconductor wafer 1, and they are laminated under non-heating. In the present invention, "non-heating" refers to a temperature of, for example, less than 60°C, preferably a temperature of 40°C or less. The lower limit temperature is not particularly limited, but can usually be 15°C, preferably 20°C. The method of laminating the semiconductor processing tape 3 and the semiconductor wafer 1 can be applied by a normal method without any particular limitation, but since the water-soluble uncured film 5 has sufficient adhesion (adhesiveness) to the semiconductor wafer 1, they can be laminated simply by laminating them, and if necessary, further pressurized.
During lamination, a semiconductor processing tape 3 of the same size as or smaller than the semiconductor wafer 1 is used so that the tape does not protrude from the outer periphery of the semiconductor wafer 1 when laminated to the semiconductor wafer 1. This makes it possible to prevent damage such as burning of the semiconductor processing tape 3 (water-soluble cured film 5C) protruding from the semiconductor wafer 1 by plasma, for example, in the singulation step (e) described below.

Next, the back surface 1B of the semiconductor wafer 1 having the water-soluble uncured film 5 of the semiconductor processing tape 3 bonded to the circuit surface 1A thereof as shown in Fig. 2(a-1) is ground (step (a)). As a result, as shown in Fig. 2(a-2), the semiconductor processing tape 3 is bonded to the circuit surface 1A, and the semiconductor wafer 1 is thinned to a predetermined thickness.
The method for grinding the back surface 1B of the semiconductor wafer 1 is not particularly limited, and may be a commonly applied back grinding (BG) process or an etching process, with the BG process being preferred. As the method and conditions in the process (a), commonly applied methods and conditions can be used.

In the manufacturing method of the present invention, next, as shown in Fig. 2 (FC), the water-soluble uncured film 5 of the semiconductor processing tape 3 is irradiated with radiation 5U from the side of the surface protection tape 4 (step (FC)). This allows the water-soluble uncured film 5 (curable compound containing an oxazine structure) to be cured, to obtain a water-soluble cured film 5C (cured tape for semiconductor processing).
The radiation irradiation method and conditions can be those of commonly used devices and conditions, and are appropriately set in consideration of the composition and physical properties of the water-soluble uncured film 5. For example, a known ultraviolet ray irradiation device can be used, and conditions can be selected from an ultraviolet ray intensity of 10 to 1000 mW/cm ² and an irradiation time of 5 to 100 seconds.

When the adhesive layer 4B contains a radiation-curable adhesive, the adhesive layer 4 is also cured together with the water-soluble uncured film 5 in step (FC).

In the manufacturing method of the present invention, next, as shown in FIG. 3(b), the semiconductor wafer 1 obtained in step (FC) is supported and fixed to a dicing tape 11 via a ring frame 12 (step (b)).
The ring frame 12 and dicing tape 11 used in step (b), as well as the method of supporting and fixing, may be any commonly used method or may be applied without any particular limitation. For example, the dicing tape 11 may be a laminated tape of a base film 11A and a pressure-sensitive adhesive layer 11B, and specifically, the tape described in Patent Document 2 may be used.

3(c), the surface protection tape 4 (base film 4A and adhesive layer 4B) of the semiconductor processing cured tape 3 is peeled off from the water-soluble cured film 5C (step (c)). In this manner, the surface protection tape 4 is removed to expose the water-soluble cured film 5C, thereby obtaining a semiconductor wafer 1 having the water-soluble cured film 5C bonded to the circuit surface 1A.
The surface protection tape 4 may be peeled off with a force equal to or greater than the peeling force between the water-soluble cured film 5C and the surface protection tape 4, and when the pressure-sensitive adhesive layer 4B contains a radiation-curable pressure-sensitive adhesive, the surface protection tape 4 can be easily peeled off from the water-soluble cured film 5C by irradiating radiation from the surface protection tape 4 side to cure the pressure-sensitive adhesive layer 4B. A typical method can be used as a specific method for peeling the surface protection tape 4.

In the manufacturing method of the present invention, next, as shown in Fig. 3(d-1), a laser is irradiated along the intended cutting regions (streets, not shown in Fig. 3(d-1)) of the semiconductor wafer 1 obtained in step (c) to cut the water-soluble cured film 5C (step (d)). Thus, as shown in Fig. 4(d-2), grooves 8 that enable irradiation of the semiconductor wafer 1 with plasma, as described below, are provided in the water-soluble cured film 5C to individualize the water-soluble cured film 5C. As a result, the intended cutting regions of the semiconductor wafer 1 are exposed at the bottom of the grooves 8. It is preferable that the width of the grooves 8 to be formed is equal to or smaller than the width of the streets.
As a method for cutting the water-soluble cured film 5C, for example, as shown in FIG. 3(d-1), a laser grooving method is exemplified in which a laser beam 7 outputted (emitted) from a laser beam irradiation means 6 is irradiated onto the water-soluble film 5 while moving the laser beam 7 relatively along the street to cut the film. As the laser beam irradiation means 6, for example, the device described in Patent Document 2 can be used. Even when the water-soluble cured film 5C of the semiconductor processing cured tape 3 is cut by laser irradiation, the individual pieces of the water-soluble cured film 5C do not soften or melt, and grooves 8 of a predetermined size and shape can be formed. Moreover, the water-soluble cured film 5C is not easily deformed over time, and the grooves 8 can maintain the groove width at the time of formation for a long period of time.
The groove formation conditions in the laser grooving method may be those normally applied, but are appropriately set in consideration of the composition, physical properties, etc. of the water-soluble cured film 5C. For example, the conditions for the laser grooving method may be selected from the following conditions: output power of 0.3 to 4.0 W, frequency of 50 to 100 kHz, and processing feed rate of 1 to 800 mm/sec.

4(e), plasma 10A is irradiated onto the exposed portion of the semiconductor wafer 1 from the cut (diced) water-soluble cured film 5C side to perform plasma treatment (step (e)). In this way, the semiconductor wafer 1 is etched and diced into individual chips.
The method for dividing the semiconductor wafer 1 can be a commonly used plasma dicing method without any particular limitations. In the manufacturing method of the present invention, as shown in Fig. 4(e), the method is performed under appropriate conditions using a plasma etching device 10. For example, the device described in Patent Document 2 can be used as the plasma etching device 10. Specifically, the conditions for plasma dicing are that a fluorine-based gas such as _SF6 is introduced, and the etching rate can be selected from 0.5 to 10 µm/s.

4(f), the cut (individualized) water-soluble cured film 5C is then washed with non-heated water (usually pure water) 9 (step (f)). In this manner, the water-soluble cured film 5C is dissolved and removed to obtain the semiconductor chip 2.
The method for cleaning and removing the water-soluble cured film is not particularly limited as long as it is a method for contacting the water-soluble cured film with non-heated water. For example, a method may be used in which the assembly of the individualized semiconductor chips 2 is held on a spinner table while being fixed to the ring frame 12, and cleaning water consisting of non-heated water 9 and air is sprayed from a nozzle located above the center of the assembly of the semiconductor chips 2 while rotating the assembly of the semiconductor chips 2, and then air is sprayed from an air nozzle onto the semiconductor chips 2 to dry them.
Since the water-soluble cured film of the semiconductor processing tape of the present invention exhibits sufficient solubility in non-heated water as described above, non-heated water can be used as the water for washing the water-soluble cured film in this step, and this step can be carried out simply and energy-savingly. The temperature of the washing water can be, for example, less than 60°C, and preferably 40°C or less. The lower limit of the water temperature is not particularly limited, but can usually be 15°C, and is preferably 20°C.
The water washing method is not particularly limited, and examples thereof include a method of spraying non-heated water onto the assembly of semiconductor chips, a method of applying non-heated water onto the assembly of semiconductor chips, and a method of immersing the assembly of semiconductor chips in non-heated water.
The water washing conditions are appropriately determined taking into consideration the water solubility and thickness of the water-soluble cured film, and can be selected from, for example, conditions of a water amount of 10 to 500 mL/min, a water washing time of 1 to 5 minutes, and a drying time of 1 to 5 minutes.

In the manufacturing method of the present invention, as shown in FIG. 4(g), a pick-up step (g) can be performed to pick up the assembly of semiconductor chips 2 (singulated semiconductor wafer 1) obtained in step (f). The pick-up step (g) can be performed using a commonly used method without any particular restrictions. For example, as shown in FIG. 4(g), a method can be used in which the semiconductor chip 2 is pushed up together with the dicing tape 11 by a pin 15 and adsorbed by a collet 16 to pick up the semiconductor chip 2.

The present invention will be described in more detail below with reference to examples and comparative examples, but the present invention is not limited to the following examples.

[Preparation of uncured tape for semiconductor processing]
Example 1
(1) Preparation of Surface Protection Tape 1.5 parts by mass of Coronate L (product name, manufactured by Tosoh Corporation) as a curing agent was dissolved in ethyl acetate for 100 parts by mass of an acrylic polymer containing 2-ethylhexyl acrylate as a constituent component, to obtain an ethyl acetate solution of adhesive. This solution was applied onto a release-treated PET film (Therapeel WZ (product name), thickness 25 μm, manufactured by Toray Industries, Inc.) so that the thickness after drying would be 30 μm, and then dried by heating. Thereafter, the adhesive layer was bonded to a substrate film (Nipolon Hard 4010 (product name, manufactured by Tosoh Corporation) made of polyethylene extrusion-formed to a thickness of 100 μm, to prepare a surface protection tape with a PET film.

(2) Preparation of water-soluble uncured film 100 parts by mass of PVP-K90 (Polyvinylpyrrolidone K90 (trade name), manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was dissolved in water with 100 parts by mass of acryloylmorpholine (ACMO (registered trademark)) as a curable compound containing an oxazine structure, 5 parts by mass of a photoradical initiator (KIP-100F (trade name)), 30 parts by mass of polyethylene glycol (PEG600) as a low molecular weight compound, and 5 parts by mass of Tinuvin 477 (product name, manufactured by BASF) as an ultraviolet absorber, to obtain a water-soluble film solution. The obtained solution was applied to a release-treated PET film (Therapeel WZ (trade name), thickness 25 μm, manufactured by Toray Industries, Inc.) so that the thickness after drying was 10 μm, and the film was dried by heating to prepare a water-soluble uncured film with a PET film.

(3) Preparation of Uncured Tape for Semiconductor Processing After peeling off the PET film from the surface protection tape with PET film obtained in (1) above, the adhesive layer of the surface protection tape and the water-soluble uncured film of the water-soluble uncured film with PET film were laminated together to prepare an uncured tape for semiconductor processing having a four-layer laminate structure of base film/adhesive layer/water-soluble uncured film/PET film.

The weight average molecular weight (Mw) of polyvinylpyrrolidone K90 and polyethylene glycol PEG600 (product names, manufactured by Sanyo Chemical Industries, Ltd.) was measured as a value (polyethylene glycol/polyethylene oxide (PEG/PEO) equivalent value) when measured by GPC (Gel Permeation Chromatography) under the following conditions.

GPC conditions:
Column: TSKgel SuperMultiporePW-M (6.0 mm I.D. x 15 cm)
Eluent: 100 mmol/L _NaNO3
Flow rate: 0.6 mL / min
Detector: RI
Temperature: 25°C
Injection volume: 20 μL
Sample preparation: A 3 mg/mL solution of the sample was prepared using pure water.

The retention volume obtained by GPC measurement was converted to molecular weight using a calibration curve prepared using PEG/PEO for molecular weight calibration, which was an Agilent polyethylene glycol/polyethylene oxide standard kit.

<Examples 2 to 8 and Comparative Examples 1 to 3>
In the "Preparation of Water-Soluble Film" step of Example 1, the uncured tapes for semiconductor processing of Examples 2 to 8 and Comparative Examples 1 to 3 were each produced in the same manner as in Example 1, except that the material, content (composition), and thickness forming the water-soluble film were changed to the material, content, and thickness shown in the "Water-Soluble Film" column of Table 1 or Table 2.
In Comparative Example 2, the components could not be mixed, and a water-soluble uncured film could not be produced.

The materials used in each of the examples and comparative examples are shown below, and Tables 1 and 2 show the weight average molecular weights of each material measured by the above-mentioned method.
<Water-soluble uncured film>
(Polymer Compound)
PVP-K90: Polyvinylpyrrolidone K90 (product name), manufactured by Fujifilm Wako Pure Chemical Industries, Ltd. Poval 60-98: Polyvinyl alcohol, saponification degree 98%, manufactured by Kuraray Co., Ltd. (curable compound containing an oxazine structure)
ACMO: acryloylmorpholine, manufactured by KJ Chemical Co., Ltd. Acrylic monomer: 1,6-hexanediol diacrylate, manufactured by Shin-Nakamura Chemical Co., Ltd. M5700: trade name, 2-hydroxy-3-phenoxypropyl acrylate, manufactured by Toagosei Co., Ltd.

(Photoradical initiator)
KIP-100F: Trade name, a mixture of Oligo[2-hydroxy-2-methyl-1-[4-(1-methylvinyl)phenyl]propanone] and 2-hydroxy-2-methylpropiophenone, manufactured by BASF (low molecular weight compound)
PEG 600: Polyethylene glycol, manufactured by Sanyo Chemical Industries, Ltd. PEG 400: Polyethylene glycol, manufactured by Sanyo Chemical Industries, Ltd. (Other components)
Tinuvin 477: UV absorber, manufactured by BASF

<Adhesive Layer>
2eha: acrylic polymer containing 2-ethylhexyl acrylate as a constituent component, manufactured by Shin-Nakamura Chemical Co., Ltd. Coronate L: hardener shown below, manufactured by Tosoh Corporation

[test]
The uncured tapes for semiconductor processing obtained in the above-mentioned Examples and Comparative Examples were tested for the following items. The results are summarized in Table 1 or Table 2.

<Test 1: Wafer Adhesion>
The adhesion of each of the uncured tapes for semiconductor processing produced in each of the Examples and Comparative Examples to a semiconductor wafer was evaluated by measuring the peel force (N/25 mm) according to the test described below.
The water-soluble film solution prepared in the same manner as in the Examples and Comparative Examples was applied to a PET film that had been subjected to an adhesion treatment, and then dried by heating to prepare a test tape of PET film (thickness 38 μm)/water-soluble uncured film (thickness 10 μm). The adhesion treatment was performed by subjecting the surface of the PET film to a corona treatment at a strength of 5 A.
Next, the obtained test tape was cut into a width of 25 mm, and the water-soluble uncured film surface of the test tape was laminated to the mirror surface of a silicon wafer at a temperature of 23°C. This lamination was performed by overlapping the test tape on the silicon wafer and running a rubber roller with a load of 2 kg back and forth on the surface of the test tape three times. The maximum peel strength between the water-soluble uncured film and the wafer immediately after lamination and after leaving the test tape in an environment of a temperature of 23°C and a humidity of 50 RH% for 1 hour after lamination was measured using Strograph VG1F (trade name, manufactured by Toyo Seiki Co., Ltd.) under the conditions of 23°C, peel angle of 180°, and peel speed of 300 mm/min. The conditions other than the above conditions were in accordance with Japanese Industrial Standards (JIS) Z 0237:2009.
The maximum peel strength (N/25 mm) immediately after lamination and the maximum peel strength (N/25 mm) after leaving for 1 hour after lamination were evaluated according to the following evaluation criteria.

- Evaluation criteria -
○: The maximum peel strength immediately after lamination and the maximum peel strength after standing for 1 hour after lamination are both greater than 1 N/25 mm. △: The maximum peel strength after standing for 1 hour after lamination is greater than 1 N/25 mm. ×: The maximum peel strength after standing for 1 hour after lamination is 1 N/25 mm or less, or the water-soluble film is partially peeled off from the wafer.

Furthermore, the water-soluble cured film of the semiconductor processing tape prepared in the examples did not peel off from the silicon wafer when the surface protection tape was peeled off in step (c) of the semiconductor chip manufacturing method of the present invention, and the water-soluble cured film also adhered firmly to the silicon wafer.

<Test 2: Laser grooving resistance (heat resistance) test>
The PET film was peeled off from each semiconductor processing tape obtained in each Example and Comparative Example, and the surface of the water-soluble uncured film was laminated to the mirror surface of a silicon wafer at a temperature of 23°C. This lamination was performed by overlapping the semiconductor processing tape on the silicon wafer, and reciprocating a rubber roller with a load of 2 kg on the surface of the semiconductor processing tape three times. Thereafter, ultraviolet rays of 1000 mJ/ ^cm2 were irradiated using a metal halide lamp with an intensity of 100 mW/ ^cm2 to cure the water-soluble uncured film. Next, the water-soluble cured film exposed by peeling off the surface protection tape was cut using a laser dicer DFL7160 (trade name, manufactured by Disco) to form a groove. The laser grooving conditions were 1 W output, 100 Hz frequency, 50 mm/sec processing speed, and 10 μm groove width. The wafer portion (exposed portion of the wafer) after cutting the water-soluble cured film was observed under a microscope, and the groove widths of the formed grooves were measured at 10 points at a depth of 1 μm from the surface layer at intervals of 100 μm along the groove length. The average value of the 10 measured widths was calculated and evaluated based on the following evaluation criteria.
This test is a test to evaluate the laser grooving resistance (heat resistance) of a water-soluble cured film, that is, the resistance to laser grooving that does not soften or melt due to the heat of laser irradiation, does not flow down into the grooves (exposed parts of the wafer), and can be diced into semiconductor chips of a predetermined size by plasma etching.

- Evaluation criteria -
◯: The measured width of the formed groove is within the range of 90 to 110% of the groove formation width of 10 μm. △: The measured width of the formed groove is within the range of 60 to 140% of the groove formation width of 10 μm (excluding the range of 90 to 110%).
×: The actual width of the formed groove is less than 60% or more than 140% of the groove formation width of 10 μm.

<Test 3: Laser grooving resistance (restraint of deformation over time) test>
In the above <Test 2: Laser grooving resistance (heat resistance) test>, the wafer with the laser grooved water-soluble cured film was left for 7 days in an environment of 23° C. and 50% RH, and the groove width of the groove formed in each water-soluble cured film was measured in the same manner. The rate of change [(measured value over time/initial measured value)×100(%)] of the groove width after standing for 7 days relative to the groove width measured in the above Test 1 (initial measured value) was calculated and evaluated based on the following evaluation criteria.
This test is a test conducted under harsh conditions to evaluate the laser grooving resistance (time-dependent deformation suppression property) of a water-soluble cured film after a long period of time (7 days) to determine the property of suppressing deformation over time of the water-soluble cured film, in particular the property of suppressing dimensional change over time of grooves formed by laser irradiation, which enables individualization of semiconductor chips of a predetermined shape and size even in cases where the plasma etching step cannot be performed promptly after the laser grooving step.

- Evaluation criteria -
○: The rate of change is within the range of 90 to 110%. △: The rate of change is within the range of 60 to 140% (excluding the range of 90 to 110%).
×: The rate of change is less than 60% or more than 140%.

<Test 4: Removability by washing with water>
The PET film was peeled off from each semiconductor processing tape obtained in each Example and Comparative Example, and the surface of the water-soluble uncured film was laminated to the mirror surface of a silicon wafer at a temperature of 23 ° C., and then the water-soluble uncured film was cured. The lamination was performed by overlapping the semiconductor processing tape on the silicon wafer and reciprocating a rubber roller with a load of 2 kg on the surface of the semiconductor processing tape three times. In addition, curing was performed by irradiating ultraviolet rays of 1000 mJ / cm ² using a metal halide lamp with an intensity of 100 mW / cm ^2. Next, the surface protection tape was peeled off from the water-soluble cured film. Thereafter, the silicon wafer having the water-soluble cured film was set on a spin coater (model number: Active Co., Ltd.), and pure water with a rotation speed of 200 rpm and a water temperature of 23 ° C. was poured over 2 minutes at a water amount of 100 mL / min. After washing with water in this way, it was visually confirmed whether the water-soluble cured film remained on the silicon wafer, and it was evaluated based on the following evaluation criteria.
In the evaluation criteria of this test, "glue" refers to a mass formed when the water-soluble cured film swells with water.

- Evaluation criteria -
◯: The water-soluble cured film was dissolved and no adhesive residue was left behind. Δ: The adhesive residue of the water-soluble cured film was slight and acceptable for a semiconductor chip. ×: The adhesive residue of the water-soluble cured film exceeded the acceptable amount for a semiconductor chip, or the water-soluble cured film did not dissolve to the extent that it clogged the drainage groove (diameter 40 mm) of the spin coater.

<Test 5: Gel fraction of water-soluble cured film>
A water-soluble uncured film with a PET film was prepared in the same manner as the preparation of the water-soluble film in each of the Examples and Comparative Examples. The water-soluble uncured film with a PET film was cured. The curing was performed by irradiating the film with ultraviolet light of 1000 mJ/ ^cm2 using a metal halide lamp with an intensity of 100 mW/ ^cm2 .
The resulting water-soluble cured film was then peeled off from the PET film, and about 1 g of the water-soluble cured film was placed in 100 g of pure water under conditions of 30° C. and 50% RH, stirred at 300 rpm for 10 minutes, and passed through a 100-mesh wire net to determine the mass of the components remaining on the wire net, and the ratio to the original mass was calculated to obtain the gel fraction (%).

The above results reveal the following:
The comparative example of an uncured tape for semiconductor processing, which has a water-soluble uncured film that contains a polymeric or low molecular compound but does not contain a curable compound containing an oxazine structure, is unable to achieve both laser grooving properties after curing and adhesion to semiconductor wafers when uncured or removability by washing with water after curing, and is therefore unsuitable for use in semiconductor chip manufacturing methods that include a laser grooving process and a plasma dicing process.
In contrast, the uncured semiconductor processing tape of the embodiment, which includes a water-soluble uncured film containing a polymer compound and a curable compound having an oxazine structure, can balance the laser grooving characteristics after curing (heat resistance and time-dependent deformation suppression characteristics), adhesion to a semiconductor wafer when uncured, and water washability after curing. Therefore, the uncured semiconductor processing tape of the embodiment exhibits high water washability that allows water washability with non-heated water even after curing while balancing the laser grooving characteristics after curing and wafer adhesion when uncured. Therefore, the semiconductor processing tape of the embodiment can protect the circuit surface of the semiconductor wafer in the back grinding process, and can easily perform the laser grooving process and the plasma dicing process while ensuring the freedom of process design, and is suitable for use in a semiconductor chip manufacturing method including a laser grooving process and a plasma dicing process. It can be seen that these semiconductor processing tapes can be used in a semiconductor chip manufacturing method including a laser grooving process and a plasma dicing process to easily manufacture semiconductor chips with high dimensional accuracy without chipping while ensuring the freedom of process design.

REFERENCE SIGNS LIST 1 Semiconductor wafer 1A Circuit surface 1B Back surface 2 Semiconductor chip 3 Semiconductor processing tape 4 Surface protection tape 4A Base film 4B Adhesive layer 5 Water-soluble uncured film 5C Water-soluble cured film 5U Ultraviolet light 6 Laser light irradiation means 7 Laser light 8 Groove 9 Non-heated water 10 Plasma etching device 10A Plasma 11 Dicing tape 11A Base film 11B Adhesive layer 12 Ring frame 15 Pin 16 Collet

Claims (5)

A semiconductor processing tape comprising a water-soluble film used as a mask member for plasma dicing and a surface protection tape for protecting the circuit surface of a semiconductor wafer, the surface protection tape being laminated together,
The water-soluble film comprises a polymer compound having a weight-average molecular weight of 200,000 or more, and a radiation - curable compound having an oxazine structure. 2. The semiconductor processing tape according to claim 1, wherein the radiation -curable compound containing an oxazine structure has a (meth)acryloyl group. The semiconductor processing tape according to claim 1 or 2, in which the gel fraction of the water-soluble film when hardened and stirred in 100 g of water at 30°C for 10 minutes is 10% or less. 4. The semiconductor processing tape according to claim 1, wherein the content of the radiation -curable compound having an oxazine structure in the water-soluble film is 100 to 300 parts by mass per 100 parts by mass of the polymer compound. A step (a) of grinding the back surface of a semiconductor wafer in which the water-soluble film in the semiconductor processing tape according to any one of claims 1 to 4 is laminated to the circuit surface of the semiconductor wafer without heating;
a step (FC) of irradiating the water-soluble film in the semiconductor processing tape from the surface protection tape side with radiation to harden the water-soluble film;
(b) supporting and fixing the semiconductor wafer to a dicing tape via a ring frame;
a step (c) of peeling a surface protection tape of the semiconductor processing tape from the cured water-soluble film to expose the water-soluble film;
A step (d) of irradiating the hardened water-soluble film with a laser along a region to be cut of the semiconductor wafer to form a groove;
a step (e) of subjecting the semiconductor wafer to a plasma treatment from the water-soluble film side cut in the step (d) to separate the semiconductor wafer;
(f) a step of washing the cut water-soluble film with non-heated water to dissolve and remove the film;
A method for manufacturing a semiconductor chip comprising the steps of:

Images