KR20230024542A - Adhesive film for wafer back grinding - Google Patents

Abstract

The present invention provides an adhesive film for grinding the back side of a wafer, which comprises: a multilayer base including an upper base layer and a lower base layer; a first adhesive layer disposed on the upper base layer; and a second adhesive layer interposed between the upper base layer and the lower base layer, wherein the second adhesive layer is formed from an adhesive composition including a light-transmitting adhesive resin and light scattering particles and satisfies the following formula 1, 0.05 <= | A-B | <= 0.2, and the light scattering particle has the refractive index of 1.42 to 1.60. Accordingly, the generation of a residual adhesive in a process of grinding the back side of a wafer can be reduced and inhibited, the adhesive film has excellent buffering effects on the surface of the wafer, and the uniformity in the thickness of the wafer after the process of grinding the back side of a wafer can be enhanced. In formula 1, A is the refractive index of the light-transmitting adhesive resin and B is the refractive index of the light scattering particle.

Description

Adhesive film for grinding the back of the wafer {ADHESIVE FILM FOR WAFER BACK GRINDING}

The present invention relates to an adhesive film used to protect the surface of a wafer in a wafer back grinding (wafer lapping or wafer thinning) process. More specifically, the present invention relates to an adhesive film for grinding the backside of a wafer having excellent processability by reducing or eliminating the generation of adhesive residue when removing (peeling) the adhesive film after grinding the backside of the wafer. will be.

With the recent development of technology, miniaturization, high density, and thinning of semiconductor chips are required, and accordingly, thinning of wafers is also required. A typical method for thinning a wafer chip is grinding the back side of the wafer to reduce the thickness, and the thinning of the wafer may be achieved by performing a grinding process according to the type or specification of an electronic device in which the semiconductor chip is used.

Since grinding the backside of a wafer of a semiconductor chip is a process in which a physical impact is applied, in order to protect the surface of the wafer, grinding the backside of the wafer is generally performed with an adhesive film for grinding the backside of the wafer attached. Such an adhesive film includes an adhesive layer for bonding the surface of a substrate and a wafer, and a buffer layer or shock absorbing layer is generally formed on the back surface of the substrate for a buffer effect. Also, generally, the adhesive layer is formed of an energy ray-curable adhesive composition.

Further, in order to remove the adhesive film for the wafer backside grinding process from the wafer surface after grinding the backside of the wafer, energy rays are irradiated to lower the adhesive force and peel off.

On the other hand, in accordance with the recent rapid development of information and communication technology and the expansion of the market, there is a demand for higher density semiconductor devices. Accordingly, the thickness of the active layer disposed on the wafer surface increases, and the unevenness (or pattern) of the active layer gradually increases. For this reason, when the adhesive film for grinding the backside of the wafer is peeled off, energy ray curing does not sufficiently progress in the shaded area caused by the unevenness of the active layer in some cases. As a result, the adhesive strength of the adhesive film for grinding the backside of the wafer is not sufficiently lowered and the peeling force is lowered, so that the adhesive residue derived from the adhesive film easily remains on the wafer surface, impairing processability and consequently manufacturing semiconductors. It can adversely affect the quality of chips, and there is a technical need to solve this problem.

The present invention is for grinding the backside of a wafer, which can reduce or suppress the generation of adhesive residue when the adhesive film for grinding the backside of the wafer is peeled off after the wafer backside grinding process, even if there is a relatively large concavo-convex portion on the wafer or the active layer on the wafer surface. It aims at providing an adhesive film.

The object of the present invention is not limited to the above-mentioned object, and other objects and advantages of the present invention not mentioned above can be understood by the following description and will be more clearly understood by the examples of the present invention. It will also be readily apparent that the objects and advantages of the present invention may be realized by means of the instrumentalities and combinations thereof set forth in the claims.

In order to solve the above technical problem, according to one aspect of the present invention, a multi-layer substrate including an upper substrate layer and a lower substrate layer; a first adhesive layer disposed on the upper substrate layer; and a second adhesive layer disposed between the upper substrate layer and the lower substrate layer, wherein the second adhesive layer is formed of an adhesive composition comprising a light-transmitting adhesive resin and light scattering particles, and the following [Formula 1 ] is satisfied, and the refractive index of the light scattering particles is 1.42 to 1.60, and an adhesive film for grinding the backside of the wafer may be provided.

[Equation 1]: 0.05 ≤ | A-B | ≤ 0.2

In [Equation 1], A is the refractive index of the light-transmitting adhesive resin, and B is the refractive index of the light scattering particles.

0.1 to 10 parts by weight of the light scattering particles may be included with respect to 100 parts by weight of the adhesive composition of the second adhesive layer.

The light scattering particles may include at least one of inorganic particles and organic particles.

An average particle diameter of the light scattering particles may be 1 μm to 50 μm.

The inorganic particles may include at least one selected from the group consisting of silica particles, glass powder, and quartz particles.

The organic particles include acrylic resin particles, polystyrene resin particles, styrene-acrylic copolymer component particles, polyethylene resin particles, epoxy resin particles, silicone resin particles, polyvinylidene fluoride particles, Teflon particles, divinylbenzene resin particles, phenol At least one selected from the group consisting of resin particles, urethane resin particles, cellulose acetate particles, nylon particles, cellulose particles, benzoguanamine resin particles, and melamine resin particles may be included.

The total light transmittance of the adhesive film for grinding the backside of a wafer of the present invention may be 70% or more, and the diffuse transmittance may be 6% or more.

The thickness of the first adhesive layer may be 10 to 100 μm, and the thickness of the second adhesive layer may be 10 to 100 μm.

The lower substrate layer and the upper substrate layer are polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate, wholly aromatic polyester, polyimide, polyamide, polycarbonate, polyacetal, modified polyphenylene oxide, polyphenylene sul, respectively. It may include at least one selected from the group consisting of pide, polysulfone, polyether ketone, and biaxially stretched polypropylene, and preferably, the lower substrate layer and the upper substrate layer may be formed of polyethylene terephthalate.

The first adhesive layer may be formed of an adhesive composition containing an acrylic adhesive resin.

The light-transmitting adhesive resin of the second adhesive layer may include a light-transmitting acrylic adhesive resin.

A shear storage modulus of the second adhesive layer at a temperature of 30° C. may be 0.05 to 5.00 MPa.

A primer layer may be further included on at least one of the upper surface of the upper substrate layer, the lower surface of the upper substrate layer, and the upper surface of the lower substrate layer.

When the adhesive film for grinding the backside of a wafer of the present invention is applied to a backside grinding process, even if a relatively large concavo-convex portion exists on the wafer or the active layer on the wafer surface, it has excellent embedding of the concavo-convex when attached to the wafer surface, and the wafer backside grinding When the adhesive film for grinding the backside of the wafer is peeled off after the process, generation of adhesive residue may be reduced or suppressed, thereby improving wafer processing processability and quality of manufactured semiconductor chips.

In addition, when the adhesive film for grinding the backside of a wafer of the present invention is applied to the grinding process, the buffer effect (or protection effect) on the surface (surface) of the wafer is excellent, and the thickness uniformity of the wafer after the grinding process can also be improved. there is.

Effects of the present specification are not limited to the effects mentioned above, and other effects not mentioned will be clearly understood by those skilled in the art from the description below. In addition to the effects described above, specific effects of the present invention will be described together while explaining specific details for carrying out the present invention.

1 is a schematic flowchart of a process of applying an adhesive film for grinding the backside of a wafer to a process of grinding the backside of a wafer according to an aspect of the present invention and then peeling it off.
2 is a cross-sectional view of an adhesive film for grinding the backside of a wafer according to an aspect of the present invention.

The above objects, features and advantages will be described later in detail with reference to the accompanying drawings, and accordingly, those skilled in the art to which the present invention belongs will be able to easily implement the technical spirit of the present invention. In describing the present invention, if it is determined that the detailed description of the known technology related to the present invention may unnecessarily obscure the subject matter of the present invention, the detailed description will be omitted. Hereinafter, preferred embodiments according to the present invention will be described in detail with reference to the accompanying drawings. In the drawings, the same reference numerals are used to indicate the same or similar components.

In the present specification, the arrangement of an arbitrary element on the "upper (or lower)" or "upper (or lower)" of a component means that an arbitrary element is placed in contact with the upper (or lower) surface of the component. In addition, it may mean that other components may be interposed between the component and any component disposed on (or under) the component.

Singular expressions used herein include plural expressions unless the context clearly dictates otherwise. In this application, terms such as "consists of" or "includes" should not be construed as necessarily including all of the various components described in the specification, some of which may not be included, or additional configurations It should be construed as possibly including more elements.

In this specification, terms such as "one side", "the other side", and "both sides" are used to distinguish one component from another component, and the components are not limited by the above terms.

In the description of this specification, "(meth)acrylate" is used as a term encompassing "acrylate" and "methacrylate", and the same applies to terms similar thereto.

Hereinafter, in describing the present invention, detailed descriptions of related known technologies that may unnecessarily obscure the subject matter of the present invention will be omitted.

1 is an exemplary flowchart of a process of applying an adhesive film 100 for grinding the backside of a wafer to a wafer, reducing adhesive force by irradiating energy rays after grinding the backside of a wafer, and peeling the film 100 according to one embodiment of the present invention.

Specifically, S1 in FIG. 1 is a step of preparing a wafer before the back side grinding process (wafer loading), and shows that the active layer 300 is disposed on the surface of the wafer 200, and the active layer 300 may cover a substrate layer including concavo-convex (pattern) present on the surface of the wafer.

S2 in FIG. 1 is a step of attaching (or attaching) the adhesive film 100 for grinding the back side of the wafer to the surface side of the wafer, thereby removing the surface of the wafer 200 and/or the active layer 300 during grinding the back side of the wafer. will play a protective role.

S3 of FIG. 1 schematically shows performing a backside grinding process, and various backgrinding equipment used in the present art can be used without limitation, for example, a wafer is ground on a chuck table. Equipment capable of rotating a grinding wheel after loading may be used. On the other hand, the thickness of the wafer before the backside grinding process ranges from about 700 to 900 μm, and after the backside grinding process, depending on the specifications of the electronic device to which the semiconductor chip is applied, the thickness of the final wafer ranges from about 30 to 300㎛. can be thinned.

S4 in FIG. 1 is a step of irradiating energy rays (typically, ultraviolet (UV)) to peel off the adhesive film 100 for grinding the backside of the wafer after the backside grinding process, compared to the wafer 200 before the backside grinding process. , which briefly shows that the thickness of the wafer 210 after the backside grinding process is reduced. Accordingly, it is common that the adhesive layer of the adhesive film 100 for grinding the back side of the wafer is formed of an energy ray-curable adhesive composition.

S5 of FIG. 1 briefly shows the step of peeling the adhesive film 100 for grinding the back side of the wafer after the back side grinding process. At this time, if the exposure of the energy rays reaching the adhesive film 100 for grinding the backside of the wafer is insufficient, the adhesive strength is not sufficiently lowered to the extent that it can be peeled off satisfactorily. residues may remain. As described above, the region R where the adhesive residue remains is exemplarily shown in FIG. 1 .

If the residue of the adhesive film 100 for grinding the backside of the wafer remains on the wafer, a problem that adversely affects processability and the quality of a semiconductor chip to be manufactured may occur. In addition, as the degree of concavo-convex (pattern) of the wafer 200 or the active layer 300 disposed on the surface of the wafer is severe, the shaded area to which energy rays cannot reach increases.

Focusing on the above problems, the present inventors have focused on scattering light on the second adhesive layer 30 of the adhesive film 100 for grinding the backside of a wafer so that the exposure of energy rays can sufficiently reach the adhesive film for grinding the backside of a wafer. Particles (P) were added.

As described above, since the second adhesive layer 30 is formed of an adhesive composition including a light-transmitting adhesive resin and light scattering particles P, the light scattering effect may be exhibited. As a result, it was found that the irradiated energy rays can be evenly dispersed on the adhesive film 100 for grinding the backside of the wafer, thereby solving the problem caused by insufficient exposure described above, and completed the present invention.

Therefore, as shown in FIG. 2, the adhesive film for grinding the backside of a wafer of the present invention includes a multi-layer substrate including an upper substrate layer 20 and a lower substrate layer 40; a first adhesive layer 10 disposed on the upper substrate layer 20; and a second adhesive layer 30 disposed between the upper substrate layer 20 and the lower substrate layer 40, wherein the second adhesive layer 30 includes a light-transmitting adhesive resin and light scattering. It may be formed of an adhesive composition including the particles (P).

Hereinafter, the characteristics of the adhesive film for grinding the backside of the wafer and the structure of each layer will be described in detail.

<Multilayer substrate>

The multi-layer substrate includes a lower substrate layer 40 , an upper substrate layer 20 and a second adhesive layer 30 . The first adhesive layer 10 is disposed on the upper substrate layer 20 , and the second adhesive layer 30 is disposed between the lower substrate layer 40 and the upper substrate layer 20 . In the adhesive film for grinding the backside of a wafer according to the present invention, the multilayer substrate has a sandwich structure in which the second adhesive layer 30 is disposed between the lower substrate layer 40 and the upper substrate layer 20 .

The lower substrate layer 40 and the upper substrate layer 20 may be formed of a material having a high tensile modulus. More specifically, the lower substrate layer 40 and the upper substrate layer 20 may have a tensile modulus of 1,000 MPa or more, for example, 1,200 MPa or more, 1,500 MPa or more, 2,000 MPa or more, or 3,000 MPa or more, at this time Tensile modulus is based on measurements at 23°C.

When the tensile modulus of the lower substrate layer 40 and the upper substrate layer 20 is relatively low, less than 1,000 MPa, the bearing capacity for the wafer or semiconductor chip is low, and collision of the semiconductor chip occurs in the back grinding process (back grinding process) There is a possibility.

The lower substrate layer 40 and the upper substrate layer 20 are each made of polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polybutylene terephthalate (PBT), polyester such as fully aromatic polyester, polyimide ( PI), polyamide (PA), polycarbonate (PC), polyacetal, modified polyphenylene oxide, polyphenylene sulfide, polysulfone, polyether ketone, and a group consisting of oriented poly-propylene It may include one or more selected from.

In addition, the lower substrate layer 40 and the upper substrate layer 20 may be made of the same material, for example, the lower substrate layer 40 and the upper substrate layer 20 may be made of a polyethylene terephthalate (PET) material. .

The thickness of the lower substrate layer 40 and the upper substrate layer 20 is not particularly limited and may have the same thickness. For example, each of the lower substrate layer 40 and the upper substrate layer 20 may have a thickness of about 10 μm to about 150 μm. On the other hand, in the present invention, since the lower substrate layer 40 and the upper substrate layer 20 have a high tensile modulus, the thickness of the lower substrate layer 40 and the upper substrate layer 20, particularly the upper substrate layer 20 If it is too thick, it may be vulnerable to impact generated in the backside grinding process. Therefore, for example, the thickness of the lower substrate layer 40 and the upper substrate layer 20 may be about 150 μm or less, but is not limited thereto.

Meanwhile, a small amount of various additives such as a coupling agent, a plasticizer, an antistatic agent, and an antioxidant may be included in the lower substrate layer 40 and/or the upper substrate layer 20 as necessary.

<First adhesive layer>

In FIG. 2 , the first adhesive layer 10 is a portion that is adhered (or attached) to the wafer. The first adhesive layer 10 is not particularly limited as long as it has appropriate adhesiveness at room temperature, and is a known UV (ultraviolet ray) curable adhesive composition such as an acrylic adhesive composition, a silicone adhesive composition, a polyester adhesive composition, and a polyamide adhesive composition. , It may be formed of various adhesive compositions such as a urethane-based adhesive composition, a styrene-diene block copolymer adhesive composition, but preferably an acrylic adhesive composition.

For example, the first adhesive layer 10 may be formed of an adhesive composition containing an acrylic adhesive resin, and the acrylic adhesive resin may be a polymer of a (meth)acrylic monomer having an alkyl group having 1 to 14 carbon atoms. , Specifically, it may be one or more polymers selected from the group consisting of ethylhexyl acrylate, butyl acrylate, ethyl acrylate, methyl acrylate, acrylic acid, hydroxyethyl acrylate, and hydroxybutyl acrylate, preferably Preferably, it may be a polymer polymerized by including a monomer including a monomer to which a carboxyl group or a hydroxyl group is bonded.

In addition, the adhesive composition for forming the first adhesive layer 10 may further include a photopolymerization initiator and a crosslinking agent, and is not particularly limited as long as it is commonly used in the art.

The crosslinking agent serves to increase the cohesive strength of the pressure-sensitive adhesive composition. For example, one or more crosslinking agents such as an isocyanate crosslinking agent, an epoxy crosslinking agent, an aziridine crosslinking agent, and a metal chelate crosslinking agent may be mixed and used.

The photopolymerization initiator is a material that initiates the reaction of the UV curable crosslinking agent by UV irradiation, and is used by appropriately selecting the type and content in consideration of the curing rate of the resin composition, and may be used by mixing one or more photopolymerization initiators. . For example, hydroxycyclohexylphenylketone (Irgacure 184), 2-methyl-1 [4- (methylthio) phenyl] -2-morpholino-propan-1-one (2-methyl-1 [ 4-(methythio)phenyl]-2-morpholino-propan-1-on; Irgacure 907), α,α-methoxy-α-hydroxyacetophenone (Irgacure 651), and 2 -Hydroxy-2-methyl-1-phenyl-propan-1-one (2-hydroxy-2-methyl-1-phenyl-propan-1-one; Irgacure 1173) and the like can be used.

Meanwhile, the thickness of the first adhesive layer 10 is not particularly limited, and may be, for example, approximately 10 to 100 μm.

Although not shown in FIG. 2, it is provided on the upper surface of the first adhesive layer and may further include a release film adhered by the first adhesive layer. One surface of the release film may be subjected to release treatment. The release treatment can be used without limitation as long as it is a material that can be commonly used for release treatment in the art, and it is preferable to release treatment with silicone, for example.

<Second adhesive layer>

2, the second adhesive layer 30 is disposed between the upper substrate layer 20 and the lower substrate layer 40, and a buffer layer capable of mitigating impact on the wafer during the backside grinding process and light having a light scattering effect. It acts as a diffusion layer.

As described above, the second adhesive layer 30 of the present invention is more advantageous as it has a low shear storage modulus in order to have a buffering effect, but if it has an excessively low shear storage modulus, the buffer layer is heated at a high temperature due to a temperature increase during the grinding process. Problems such as flowing or non-uniform thickness may occur. Considering the above points, the shear storage modulus of the second adhesive layer 30 at a temperature of 30° C. is preferably 0.05 to 5 MPa, more preferably 0.05 to 3 MPa, and 0.05 to 2.5 MPa. It is most preferable to be The adhesive film 100 for grinding the backside of a wafer including the second adhesive layer 30 of the present invention has an excellent buffering effect on the surface of the wafer and can improve the thickness uniformity of the wafer after the backside grinding process. .

In addition, the second adhesive layer 30 of the present invention is formed of an adhesive composition containing a light-transmitting adhesive resin and light scattering particles (P), and thus acts as a light diffusion layer that imparts a light scattering effect. Due to the light scattering effect of the second adhesive layer 30 as described above, energy rays irradiated to peel off the adhesive film for grinding the back side of the wafer are evenly distributed, and the generation of adhesive residue during peeling can be reduced or suppressed. , it is possible to improve processability and quality of semiconductor chips to be manufactured excellently. In addition, the adhesive composition for forming the second adhesive layer 30 can be used by mixing one or more cross-linking agents such as metal chelate, isocyanate, and epoxy, if necessary.

Therefore, it was experimentally derived that the difference in refractive index between the light-transmitting adhesive resin and the light scattering particles P is preferably 0.05 to 0.2 so that the second adhesive layer 30 can exhibit a scattering effect, and this relationship is It can be embodied as the following [Formula 1].

[Equation 1]: 0.05 ≤ | A-B | ≤ 0.2

In [Equation 1], A is the refractive index of the light-transmitting adhesive resin, and B is the refractive index of the light scattering particles.

In addition, based on 100 parts by weight of the adhesive composition for forming the second adhesive layer 30 of the present invention, it is preferable to include 0.1 to 10 parts by weight of the light scattering particles (P). If the content of the light scattering particles (P) is less than 0.1 part by weight, the light scattering effect may not be sufficient. In addition, if the content of the light scattering particles (P) is more than 10 parts by weight, the total light transmittance is lowered, so that curing by energy rays cannot proceed to a required extent in the peeling process, and the effect of reducing the adhesive residue may not be sufficient, including an excessive amount of particles This may adversely affect the uniformity of the wafer after the wafer backside grinding process.

Hereinafter, the light-transmitting adhesive resin and the light scattering particles (P) included in the second adhesive layer 30 will be described in detail.

light scattering particles

The light scattering particles (P) are particles for diffusing or scattering light, and are preferably transparent fine particles to have light transmittance. In addition, the light scattering particles (P) preferably have a sphere shape so that the light scattering effect can be uniform. In addition, to have high light transmittance, the refractive index of the light scattering particles (P) is preferably in the range of 1.42 to 1.60.

In addition, the average particle diameter of the light scattering particles (P) is preferably 1 to 50 μm, more preferably 1 to 10 μm. If the average particle diameter is less than 1 μm, the light diffusing effect or light scattering effect is low, and if it exceeds 50 μm, the particles are too coarse, so that the second adhesive layer 30 including the same and the adhesive film 100 for grinding the backside of the wafer Thickness uniformity may deteriorate. On the other hand, the average particle diameter is measured based on the coulter counter method. It is generally desirable that the average particle diameter of the light scattering particles (P) be uniform to improve uniformity, but in order to adjust the diffusion characteristics, two or more types of light scattering particles (P) having different materials or particle diameters may be mixed and used. may be

As long as the above conditions are satisfied, the type of light scattering particles P is not particularly limited, and may include at least one of inorganic particles and organic particles. The inorganic particles may include at least one selected from the group consisting of silica particles, glass powder, and quartz particles. The organic particles include acrylic resin particles, polystyrene resin particles, styrene-acrylic copolymer component particles, polyethylene resin particles, epoxy resin particles, silicone resin particles, polyvinylidene fluoride particles, Teflon particles, divinylbenzene resin particles, phenol At least one selected from the group consisting of resin particles, urethane resin particles, cellulose acetate particles, nylon particles, cellulose particles, benzoguanamine resin particles, and melamine resin particles may be included.

light transmissive adhesive resin

In order for the second adhesive layer 30 of the present invention to function as a light diffusion layer, the adhesive resin forming it needs to be selected as a light-transmitting adhesive resin.

For example, the refractive index of the light-transmitting adhesive resin is preferably in the range of 1.40 to 1.70, more preferably in the range of 1.45 to 1.55.

The light-transmitting adhesive resin is not particularly limited as long as it is a light-transmitting resin material such as a light-transmitting thermoplastic resin, thermosetting resin, or photocurable resin. For example, room temperature pressure-sensitive adhesive resins such as polyethylene resins, polypropylene resins, cycloolefin resins, polyester resins, epoxy resins, polyurethane resins, silicone resins, and acrylic resins may be used, or polymethylmethaethylene Resins that do not have room temperature pressure-sensitive adhesive, such as acrylate resins, polycarbonate resins, polyethylene terephthalate resins, and polyvinyl chloride resins, can also be used.

Preferably, in the present invention, an acrylic adhesive resin may be used as the light-transmitting adhesive resin. For example, the acrylic adhesive resin may be a homopolymer or copolymer of acrylic monomers such as acrylic acid and its esters, methacrylic acid and its esters, acrylamide, and acrylonitrile, and at least one of the above-mentioned acrylic monomers. and a copolymer of vinyl monomers such as vinyl acetate, maleic anhydride, and styrene. Moreover, monomers, such as ethyl acrylate, butyl acrylate, and 2-ethylhexyl acrylate, which show adhesiveness; Monomers, such as vinyl acetate, acrylamide, acrylonitrile, styrene, and methacrylate, which serve as cohesion components; Acrylic acid, methacrylic acid, itaconic acid, maleic anhydride, hydroxyethyl methacrylate, hydroxypropyl methacrylate, dimethylaminoethyl methacrylate, methylol acrylamide, glycidyl methacrylate that can further improve adhesive strength Functional group containing monomers, such as a rate; Fluorine-containing acrylate or sulfur-containing acrylate for adjusting the refractive index; can be further copolymerized with one selected from the group consisting of, and used as an acrylic adhesive resin.

Meanwhile, the thickness of the second adhesive layer 30 is not particularly limited, and may be, for example, about 10 to 100 μm.

<Adhesive film for grinding the back side of the wafer>

The adhesive film 100 for grinding the backside of a wafer according to the present invention preferably has a total light transmittance of 70% or more and a diffuse transmittance of 6% or more.

Specifically, in order to peel the adhesive film 100 for grinding the backside of the wafer from the wafer, energy rays (typically, UV) are irradiated to reduce the adhesive force so that the curing reaction proceeds. At this time, it is preferable that the total light transmittance is 70% or more so that the curing reaction by the energy rays can sufficiently proceed.

On the other hand, as the second adhesive layer 30 of the present invention includes the light scattering particles P, the light scattering or light diffusion effect is expressed in the entire structure of the adhesive film 100 for grinding the backside of the wafer. In order to sufficiently exhibit the light scattering or light diffusion effect, it is preferable that the diffuse transmittance of the entire structure of the adhesive film 100 for grinding the backside of the wafer is 6% or more.

Hereinafter, the configuration and operation of the present invention will be described in more detail through preferred embodiments of the present invention. However, this is presented as a preferred example of the present invention and cannot be construed as limiting the present invention by this in any sense. Since contents not described herein can be sufficiently technically inferred by a person skilled in the art, the description thereof will be omitted.

Preparation Example 1: Preparation of the first adhesive composition for forming the first adhesive layer

A mixture of monomers consisting of 27 g of butyl acrylate (BA), 48 g of methyl acrylate (MA) and 25 g of hydroxyethyl acrylate (HEA) is introduced into a reactor equipped with a cooling device so that nitrogen gas is refluxed and the temperature is easily controlled. did

Subsequently, 100 parts by weight of ethyl acetate (EAc) as a solvent was added to 100 parts by weight of the monomer mixture, and the mixture was sufficiently mixed at 30° C. for 30 minutes or more while injecting nitrogen into the reactor to remove oxygen. Thereafter, the temperature was raised and maintained at 50° C., and 0.1 parts by weight of azobisisobutyronitrile, a reaction initiator, was added, and the reaction was initiated, followed by polymerization for 24 hours to prepare a primary reactant.

24.6 parts by weight of 2-methacroyloxyethyl isocyanate (MOI) and 1 part by weight of a catalyst (DBTDL: dibutyl tin dilaurate) based on MOI were mixed with the primary reactant, and reacted at 40 ° C. for 24 hours, resulting in a weight average molecular weight of 500,000 An acrylic adhesive resin was obtained.

Based on 100 parts by weight of the acrylic adhesive resin, after adding 0.1 parts by weight of Irgacure 184 (BASF) as a photopolymerization initiator and 2 parts by weight of an isocyanate-based crosslinking agent (Nippon Polyurethane Kogyo, trade name: Coronate C) as a crosslinking agent, sufficiently By mixing, the first adhesive composition for forming the first adhesive layer was prepared.

Preparation Example 2: Preparation of a second adhesive composition for forming a second adhesive layer

20 parts by weight of butyl acrylate, 10 parts by weight of ethylhexyl acrylate, 55 parts by weight of methyl acrylate, 7 parts by weight of 2-hydroxyethyl acrylate, 8 parts by weight of acrylic acid, 0.05 part by weight of azobisisobutyronitrile, ethyl acetate A mixture obtained by mixing 100 parts by weight was polymerized at 60° C. for 6 hours under a nitrogen atmosphere to obtain an acrylic adhesive resin having a weight average molecular weight of 600,000.

Based on 100 parts by weight of the acrylic adhesive resin, 3 parts by weight of an isocyanate-based crosslinking agent (manufactured by Nippon Polyurethane Kogyo Co., Ltd., trade name "Coronate C") is added and sufficiently mixed to form a second adhesive composition for forming a second adhesive layer. was manufactured.

The refractive index of the prepared second adhesive composition was measured to be 1.48, and was measured using an Abbe refractometer.

Example 1

The first adhesive composition of Preparation Example 1 is coated on the release-treated PET (polyethylene terephthalate film, thickness 50 μm) so that the thickness of the first adhesive layer is 20 μm, and the biaxially stretched polyethylene terephthalate having a thickness of 50 μm ( PET) film (substrate) was bonded to produce a first composite film having a first adhesive layer having a thickness of 120 μm.

Subsequently, based on 100 parts by weight of the second adhesive composition of Preparation Example 2, 1.0 parts by weight of organic particles (referred to as 'b1') of a polystyrene component having a refractive index of 1.59 and an average particle diameter of 3 μm were added as light scattering particles, and then , were thoroughly mixed and coated on a biaxially stretched polyethylene terephthalate (PET) film having a thickness of 25 μm to a thickness of 20 μm to prepare a second composite film having a second adhesive layer having a thickness of 45 μm.

The first composite film and the second composite film were bonded together to prepare an adhesive film for grinding the backside of the wafer having a total thickness of 115 μm (the thickness of the release PET was excluded from the total thickness).

Examples 2-3 and Comparative Examples 1-3

In Example 1, the adhesive film for grinding the backside of the wafer was prepared in the same manner as in Example 1, except that the type or content of each component and the thickness of the adhesive layer were changed as shown in Table 1 below.

Experimental Example 1: Optical Characteristics Evaluation

For the adhesive films for grinding the back of the wafer of Examples 1 to 3 and Comparative Examples 1 to 3, total transmittance (T.T, %) and diffuse transmittance (D.T , %) was measured, and the results are shown in Table 1.

Experimental Example 2: Measurement of the shear storage modulus of the second adhesive layer

The second adhesive layer for forming the second adhesive layer of the adhesive film for grinding the back of the wafer of Examples 1 to 3 and Comparative Examples 1 to 3 using a shear storage modulus measuring device, Rheometer (TA instruments; ARES-G2). The shear storage modulus of a sample having a size of 8 mm in diameter x 1 mm in thickness obtained by laminating a single-layer adhesive layer formed of an adhesive composition solution was measured at 1 Hz in an environment of -20 ° C to 120 ° C, and the shear storage modulus at 30 ° C was recorded. and are shown in Table 1 below.

Experimental Example 3: Test for thickness uniformity and residue after grinding the back of the wafer

After attaching the adhesive film for grinding the back of the wafer of Examples 1 to 3 and Comparative Examples 1 to 3 on the semiconductor circuit surface (= wafer surface), back grinding equipment (DISCO; DGP8760) was used to obtain a wafer with a thickness of 725 μm. Back grinding was performed to a thickness of 100 μm.

After the backside grinding process was completed, UV A of 300 mJ/cm 2 was irradiated using exposure equipment (Semyung Vactron Co., Ltd.; TRSJ-3000). Then, heat sealing tape (MBS-100R) was thermally compressed to one outer portion of the adhesive film for grinding the backside of the wafer at 220° C., and then the adhesive film for grinding the backside of the wafer was removed.

After the backside grinding process, 20 points on the surface of the wafer from which the adhesive film was removed were observed under a microscope to check the wafer's thickness uniformity and adhesive residue, and the specific method is as follows.

(1) Adhesive residue test

The size of the residue at 20 points in the back-ground wafer was measured and evaluated as follows, and the results are shown in Table 1 below.

○: No residues with a size of 10 μm or less

△: Residues with a size of 10 μm or less

×: A large amount of residue with a size of 10 μm or more occurs

(2) Test for wafer thickness uniformity

If the standard deviation of the thickness at 20 points in the back-ground wafer was less than ±4㎛, the degree of uniformity of the thickness of the wafer was evaluated as good (○), and if the standard deviation of thickness was more than ±6㎛, the degree of uniformity of the thickness of the wafer was evaluated as poor. (x) was evaluated, and the results are shown in Table 1 below.

Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Comparative Example 3 First adhesive layer thickness (μm) 20 20 20 20 20 20 Second adhesive layer thickness (μm) 20 20 40 40 20 40 Light scattering particle content
(%) b1 (1.59) 1.0 8.0 - - 15.0 - b2 (1.42) - - 5.0 - - - b3(1.49) - - - - - 8.0 Value of Equation 1 0.11 0.11 0.06 1.48 0.11 0.01 Total transmittance (%) 83.4 79.6 71.9 86.5 59.8 85.7 Diffuse transmittance (%) 6.3 17.2 21.1 3.5 25.2 4.5 of the second adhesive layer
Shear storage modulus
(Mpa, @ 30℃) 0.15 2.32 1.45 0.12 5.33 1.96 adhesive residue
test result ○ ○ ○ × △ △ thickness uniformity
test result ○ ○ ○ ○ × ○

b1 to b3 of Table 1 are as follows.

-b1: Light scattering particles, a polystyrene component with a refractive index of 1.59, and an average particle diameter of 3㎛.

-b2: Teflon component with a refractive index of 1.42 as a light scattering particle, and an average particle diameter of 3㎛.

- b3: Light scattering particles, a polymethyl methacrylate component with a refractive index of 1.49, and an average particle diameter of 3 μm.

As can be seen from Table 1, in Examples 1 to 3 according to the present invention, the second adhesive layer functions as a buffer layer to have a protective effect during grinding the backside of the wafer, and includes light scattering particles in the second adhesive layer to form an adhesive Excellent results were also obtained in the residue test and thickness uniformity test.

On the other hand, Comparative Example 1 did not include light scattering particles in the second adhesive layer, but a large amount of residue having a size of 10 μm or more was generated in the adhesive residue test. Comparative Example 2 contained an excessive amount of light scattering particles, but poor results were obtained in the adhesive residue test and the thickness uniformity test, and the shear storage modulus of the second adhesive layer was higher than that of Examples. In Comparative Example 3, the difference in refractive index between the adhesive resin and the light scattering particles for forming the adhesive layer was too low, and did not satisfy Equation 1, so the light scattering (diffusion) effect was not sufficient, and the adhesive residue test result showed that 10 Residues of a size of less than ㎛ were generated, so the effect of suppressing the occurrence of residues was not excellently derived.

As described above, the present invention has been described with reference to the drawings illustrated, but the present invention is not limited by the embodiments and drawings disclosed in this specification, and various modifications are made by those skilled in the art within the scope of the technical idea of the present invention. It is obvious that variations can be made. In addition, although the operational effects according to the configuration of the present invention have not been explicitly described and described while describing the embodiments of the present invention, it is natural that the effects predictable by the corresponding configuration should also be recognized.

100: adhesive film for grinding the back of the wafer
200: wafer before back side grinding process
210: wafer after backside grinding process
300: active layer
R: Area where residues of adhesive remain
10: first adhesive layer
20: upper base layer
30: second adhesive layer
40: lower substrate layer
P: light scattering particles

Claims (14)

A multi-layer substrate including an upper substrate layer and a lower substrate layer;
a first adhesive layer disposed on the upper substrate layer; and
a second adhesive layer disposed between the upper substrate layer and the lower substrate layer;
including,
The second adhesive layer is formed of an adhesive composition containing a light-transmitting adhesive resin and light scattering particles, satisfies the following [Equation 1], and the light scattering particles have a refractive index of 1.42 to 1.60, characterized in that,
Adhesive film for grinding the back side of the wafer:
[Equation 1]: 0.05 ≤ | AB | ≤ 0.2
In [Equation 1], A is the refractive index of the light-transmitting adhesive resin, and B is the refractive index of the light scattering particles.
According to claim 1,
Characterized in that it comprises 0.1 to 10 parts by weight of the light scattering particles based on 100 parts by weight of the adhesive composition of the second adhesive layer.
Adhesive film for grinding the backside of a wafer.
According to claim 1,
Characterized in that the total light transmittance is 70% or more,
Adhesive film for grinding the backside of a wafer.
According to claim 1,
Characterized in that the diffuse transmittance is 6% or more,
Adhesive film for grinding the backside of a wafer.
According to claim 1,
Characterized in that the light scattering particles include at least one of inorganic particles and organic particles,
Adhesive film for grinding the backside of a wafer.
According to claim 1,
Characterized in that the average particle diameter of the light scattering particles is 1 to 50 μm,
Adhesive film for grinding the backside of a wafer.
According to claim 5,
Characterized in that the inorganic particles include at least one selected from the group consisting of silica particles, glass powder and quartz particles,
Adhesive film for grinding the backside of a wafer.
According to claim 5,
The organic particles include acrylic resin particles, polystyrene resin particles, styrene-acrylic copolymer component particles, polyethylene resin particles, epoxy resin particles, silicone resin particles, polyvinylidene fluoride particles, Teflon particles, divinylbenzene resin particles, phenol Characterized in that it comprises at least one selected from the group consisting of resin particles, urethane resin particles, cellulose acetate particles, nylon particles, cellulose particles, benzoguanamine resin particles and melamine resin particles,
Adhesive film for grinding the backside of a wafer.
According to claim 1,
The thickness of the first adhesive layer is 10 ~ 100㎛,
Characterized in that the thickness of the second adhesive layer is 10 to 100 μm,
Adhesive film for grinding the backside of a wafer.
According to claim 1,
The lower substrate layer and the upper substrate layer are polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate, wholly aromatic polyester, polyimide, polyamide, polycarbonate, polyacetal, modified polyphenylene oxide, polyphenylene sul, respectively. Characterized in that it comprises at least one member selected from the group consisting of pide, polysulfone, polyether ketone and biaxially oriented polypropylene,
Adhesive film for grinding the backside of a wafer.
According to claim 10,
The lower substrate layer and the upper substrate layer are characterized in that formed of polyethylene terephthalate,
Adhesive film for grinding the backside of a wafer.
According to claim 1,
The first adhesive layer is characterized in that formed of an adhesive composition containing an acrylic adhesive resin,
Adhesive film for grinding the backside of a wafer.
According to claim 1,
Characterized in that the light-transmitting adhesive resin of the second adhesive layer includes a light-transmitting acrylic adhesive resin,
Adhesive film for grinding the backside of a wafer.
According to claim 1,
Characterized in that the shear storage modulus of the second adhesive layer at a temperature of 30 ℃ is 0.05 ~ 5.00 MPa,
Adhesive film for grinding the backside of a wafer.

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