CN115404015B

CN115404015B - Adhesive film for wafer processing

Info

Publication number: CN115404015B
Application number: CN202210580217.9A
Authority: CN
Inventors: 郑喆; 高乾英; 崔裁原; 金尚信
Original assignee: Innox Corp
Current assignee: Innox Corp
Priority date: 2021-05-28
Filing date: 2022-05-25
Publication date: 2024-08-13
Anticipated expiration: 2042-05-25
Also published as: TWI840819B; TW202246439A; CN115404015A; KR20220161081A

Abstract

The invention provides an adhesive film for wafer processing, which comprises: a multi-layer substrate comprising 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 made of a second adhesive composition, and the second adhesive composition comprises an adhesive resin and core-shell nanoparticles.

Description

Adhesive film for wafer processing

Technical Field

The present invention relates to an adhesive film for wafer processing used for wafer processing such as film back grinding of a wafer. More specifically, the present invention relates to an adhesive film for wafer processing which has excellent surface protection effect (buffer effect) of a wafer during wafer polishing processing.

Background

Recently, miniaturization and thinning of semiconductor chips are increasingly demanded with the development of technology.

As a typical example of the thinning of the chip, there is a method of reducing the thickness by polishing the back surface of a wafer on which the chip is formed.

Recently, thinned chips have been obtained by a wafer back side grinding (DBG, dicing Before Grinding) method, and diced chips have been obtained from a wafer by forming grooves on the surface of the wafer with a dicing blade and then grinding the back side of the wafer. In the case of using the wafer back surface polishing method, since back surface polishing of the wafer and dicing of the wafer are performed simultaneously, a thinned semiconductor chip can be efficiently manufactured.

In general, when back grinding of a wafer is performed, in order to maintain a semiconductor chip, back grinding of the wafer needs to be performed in a state where an adhesive film is attached to a surface of the wafer. The adhesive film includes an adhesive layer for bonding the substrate and the wafer surface, and a buffer layer or a vibration damping layer having a buffer effect, for example, urethane acrylate, may be formed on the back surface of the substrate.

The lower the modulus (module) of such a buffer layer is, the more excellent the buffer effect is, so that the surface of the wafer can be effectively protected. However, there may be a problem that, in the case of the low modulus buffer layer, the buffer layer flows at a high temperature or becomes uneven in thickness due to an increase in temperature when the back grinding process is performed.

Disclosure of Invention

Technical problem

The purpose of the present invention is to provide an adhesive film for wafer processing, which protects the surface of a wafer with an excellent buffer effect and improves the flow control and thickness uniformity at high temperatures when the back surface grinding processing of the wafer is performed.

The objects of the present invention are not limited to the above-mentioned objects, and other objects and advantages of the present invention, which are not mentioned, can be understood through the following description, and are more clearly understood through the embodiments of the present invention. Moreover, it is apparent that the objects and advantages of the invention can be realized by the means and combinations thereof indicated by the scope of the invention.

Technical proposal

In order to solve the above-mentioned problems, an adhesive film for wafer processing according to the present invention may comprise: a multi-layer substrate comprising 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 may be made of a second adhesive composition including an adhesive resin and core-shell nanoparticles.

The average particle diameter of the core-shell nanoparticle may be 5nm to 400nm.

The core of the core-shell nanoparticle may be a polyalkyl (meth) acrylate having a glass transition temperature of-50 to 40 ℃, and the shell of the core-shell nanoparticle may be a polyalkyl (meth) acrylate having a glass transition temperature of 50 to 150 ℃.

The core-shell nanoparticle may be contained in an amount of 0.1 to 20 parts by weight with respect to 100 parts by weight of the binder resin of the second binder composition.

The modulus (modulus) of the second adhesive layer may be 0.05MPa to 2MPa in a temperature range of 60 ℃ to 90 ℃.

The recovery force (recovery force) of the adhesive film measured according to the following formula 1 may be 55% to 90%. The method for measuring the restoring force by using the formula 1 will be specifically described below.

Formula 1: restoring force (%) = (1- (X _f/X₀)) ×100

In the above formula 1, X ₀ is a thickness which is 1/2 times the original thickness of the adhesive film, and X _f is a thickness at which the adhesive film is pressed when no force is applied to the adhesive film in the case of being restored after being held for 10 seconds at X ₀.

The modulus of the lower substrate layer and the upper substrate layer may be 1000MPa or more under a temperature condition of 23 ℃.

The lower substrate layer and the upper substrate layer may each include one or more selected from the group consisting of polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate, wholly aromatic polyester, polyimide, polyamide, polycarbonate, polyacetal, modified polyphenylene oxide, polyphenylene sulfide, polysulfone, polyether ketone, and biaxially oriented polypropylene.

The binder resin of the second binder layer may include a thermosetting acrylic binder.

A primer layer may be additionally formed 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.

ADVANTAGEOUS EFFECTS OF INVENTION

The adhesive film for wafer processing of the present invention can realize excellent buffering effect (restoring force) of the wafer surface and improve fluidity control and thickness uniformity at high temperature at the time of performing back grinding processing of the wafer by including the second adhesive layer including core-shell nanoparticles therein.

The effects of the present invention are not limited to the above-mentioned effects, and other effects not mentioned can be clearly understood by those skilled in the art from the following description.

In addition to the above effects, the specific effects of the present invention will be described together in the following description of the specific embodiments of the present invention.

Drawings

Fig. 1 is a cross-sectional view schematically showing an adhesive film for wafer processing according to an embodiment of the present invention.

Fig. 2 is a cross-sectional view schematically showing an adhesive film for wafer processing according to another embodiment of the present invention.

Description of the reference numerals:

110: a substrate;

111: a lower substrate layer;

112: an upper substrate layer;

113: a primer layer;

115: a second adhesive layer;

120: a first adhesive layer.

Detailed Description

The above objects, features and advantages are described in detail below with reference to the accompanying drawings so that those skilled in the art to which the present invention pertains may easily implement the technical ideas of the present invention. In describing the present invention, if it is determined that a detailed description of known technologies related to the present invention may obscure the gist of the present invention, a detailed description thereof will be omitted. Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the drawings, the same reference numerals denote the same or similar structural elements.

In the present specification, the term "upper (or lower)" or "upper (or lower)" of a component means that not only an arbitrary structure is disposed in contact with the upper surface (or lower surface) of the component, but also another structure may be disposed between the component and an arbitrary structure disposed on (or under) the component.

In this specification, the singular reference is used to include the plural reference unless the context clearly indicates otherwise. In the present application, terms such as "comprising" or "including" should not be construed as necessarily including all the structural elements described in the specification, but may include no part of the structural elements therein or may include additional structural elements.

In the present description, terms such as "one side", "another side", and "both sides" are used only to distinguish one component from other components, and the components are not limited to the terms described above.

In the present invention, wafer processing may include a wafer back side grinding (back side grinding) process, a dicing process, a pick-up process of diced semiconductor chips, and the like.

In the following, in describing the present invention, a detailed description of known techniques that may unnecessarily obscure the gist of the present invention will be omitted.

The wafer-processing adhesive film of the present invention will be described in detail below.

The adhesive film for wafer processing of the present invention may include: a multi-layer substrate comprising 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, the second adhesive layer being made of a second adhesive composition including an adhesive resin and core-shell nanoparticles.

Fig. 1 is a cross-sectional view schematically showing an adhesive film for wafer processing according to an embodiment of the present invention. Referring to fig. 1, the adhesive film for wafer processing of the present invention includes: a multilayer substrate 110; a first adhesive layer 120 disposed on the upper substrate layer 112 of the multilayer substrate; and a second adhesive layer 115 disposed between the upper substrate layer 112 and the lower substrate layer 111.

Multilayer substrate

The multi-layer substrate 110 includes a lower substrate layer 111, an upper substrate layer 112, and a second adhesive layer 115. The first adhesive layer 120 is disposed on the upper substrate layer 112, and the second adhesive layer 115 is disposed between the lower substrate layer 111 and the upper substrate layer 112. In the adhesive film for wafer processing of the present invention, the multilayer substrate forms a sandwich-type structure in which the second adhesive layer 115 is disposed between the lower substrate layer 111 and the upper substrate layer 112.

The lower substrate layer 111 and the upper substrate layer 112 may be made of a high modulus material. More specifically, the lower substrate layer 111 and the upper substrate layer 112 have a modulus of 1000MPa or more, and may have a modulus of 1200MPa or more, 1500MPa or more, 2000MPa or more, and 3000MPa or more, for example, with the modulus at this time being based on a measured value at a temperature of 23 ℃. The present invention is characterized in that the upper substrate layer 112 and the lower substrate layer 111 are made of a material having a high modulus on the side where the wafer is bonded.

When the modulus of the upper substrate layer 112 and the lower substrate layer 111 is relatively low, in other words, less than 1000MPa, the supporting force of the wafer or diced semiconductor chips is lowered, which may cause collision of the semiconductor chips in the back grinding process.

The lower substrate layer 111 and the upper substrate layer 112 may each include one or more selected from the group consisting of polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polybutylene terephthalate (PBT), polyesters such as wholly aromatic polyesters, polyimide (PI), polyamide (PA), polycarbonate (PC), polyacetal, modified polyphenylene oxide, polyphenylene sulfide, polysulfone, polyether ketone, and biaxially Oriented polypropylene (Oriented Poly-propylene).

Preferably, the materials of the lower substrate layer 111 and the upper substrate layer 112 may be the same. For example, the lower substrate layer 111 and the upper substrate layer 112 may be made of polyethylene terephthalate (PET).

Although the lower substrate layer 111 and the upper substrate layer 112 may have the same thickness, they are not limited thereto. The lower substrate layer 111 and the upper substrate layer 112 may each have a thickness of about 10 μm to 150 μm. On the other hand, in the present invention, although the lower substrate layer 111 and the upper substrate layer 112 have a high modulus, when the thicknesses of the lower substrate layer 111 and the upper substrate layer 112 are relatively thick, in particular, if the thickness of the upper substrate layer 112 is too thick, it is difficult to withstand the impact generated during the wafer processing such as back grinding. Therefore, the thickness of the lower substrate layer 111 and the upper substrate layer 112 should preferably be set to 150 μm or less.

On the other hand, the lower substrate layer 111 and/or the upper substrate layer 112 may contain a small amount of various additives, for example, coupling agents, plasticizers, antistatic agents, antioxidants, and the like.

A first adhesive layer

The first adhesive layer 120 shown in fig. 1 is the portion that is bonded to the wafer.

The first adhesive layer 120 is not particularly limited as long as it has an appropriate adhesiveness under normal temperature conditions, and various adhesives, for example, a known Ultraviolet (UV) adhesive, and the like can be applied.

The thickness of the first adhesive layer 120 is not particularly limited, and may be, for example, 10 μm to 100 μm.

Fig. 2 is a cross-sectional view schematically showing an adhesive film for wafer processing according to still another embodiment of the present invention.

Referring to fig. 2, a primer layer 113 may be additionally included on the upper surface of the upper substrate layer 112 of the multi-layered substrate. Such a primer layer 113 may be used to improve adhesion between the first adhesive layer 120 and the multilayer substrate 110.

Primer layer 113 is formed on the upper surface of upper substrate layer 112, i.e., a separate layer may be formed on the side where first adhesive layer 120 is formed. As another example, primer layer 113 may be modified from the upper surface of upper substrate layer 112.

As an example, although fig. 2 shows the primer layer 113 formed on the upper surface of the upper substrate layer 112, the present invention is not limited thereto, and the primer layer may be formed on the lower surface of the upper substrate layer 112 or the upper surface of the lower substrate layer 111.

Although not shown in fig. 2, the present invention may further include a release film disposed on the upper surface of the first adhesive layer and bonded by the adhesive layer. One side of the release film may be subjected to a release treatment. In the release treatment, any material that is generally used in the release treatment in this field may be used without limitation, and for example, silicon is preferably used for the release treatment.

A second adhesive layer

In the present invention, the second adhesive layer 115 is an adhesive layer disposed between the upper substrate layer 112 and the lower substrate layer 111, and can be used as a buffer layer or a vibration damping layer having a high buffer effect for protecting the wafer surface during wafer processing.

Preferably, the second adhesive layer of the present invention is made of a second adhesive composition comprising an adhesive resin and core-shell nanoparticles. The second adhesive layer may be manufactured by thermally curing the above-described second adhesive composition.

The binder resin of the second binder composition may contain a thermosetting acrylic binder resin, and the second binder composition may contain a thermosetting agent in addition to the binder resin.

For example, the thermosetting acrylic binder resin may be a methyl acrylate compound. Examples of the methyl acrylate compound that can be used for the thermosetting acrylic adhesive include (meth) acrylic acid esters, alkyl (meth) acrylates such as alkyl (meth) acrylates having an alkyl group with 4 or more carbon atoms, and non-urethane polyfunctional (meth) acrylic acid esters, but are not limited thereto.

Examples of the curing agent that can be used for the thermosetting acrylic adhesive include, but are not limited to, isocyanate-based crosslinking agents, carbodiimide-based crosslinking agents, oxazoline-based crosslinking agents, epoxy-based crosslinking agents, aziridine-based crosslinking agents, peroxides, and the like. The content of the curing agent may be 2 parts by weight or less with respect to 100 parts by weight of the binder resin of the second binder composition, but is not limited thereto.

In order to achieve the cushioning effect, the lower the modulus of the second adhesive layer as the cushioning layer, the more advantageous, but in the case where the modulus is too low, there is a possibility that the cushioning layer flows at a high temperature or becomes uneven in thickness due to an increase in temperature when the back grinding step is performed.

Accordingly, the present inventors have found that the above-described problems can be solved by including nanoparticles having a core-shell structure in the second adhesive layer in order to control the fluidity of the second adhesive layer due to heat generated when the back grinding process of the wafer is performed.

The average particle diameter of the core-shell nanoparticle is preferably 5nm to 400nm, more preferably 100nm to 300nm. If the average particle diameter of the nanoparticles is less than 5nm, dispersion unevenness may be caused by aggregation due to electrostatic charge between particles, and if the average particle diameter of the nanoparticles is greater than 400nm, there may be a problem that the thickness uniformity of the coating layer becomes uneven, etc. on the surface.

The core of the core-shell nanoparticle described above plays a role of maintaining modulus at high temperature by forming a crosslinked structure, and thus, is preferably made of a material having a low glass transition temperature.

The core of the core-shell nanoparticle may have a glass transition temperature of-50 to 40 ℃, more preferably-30 to 30 ℃, and most preferably-30 to 20 ℃. In the above glass transition temperature range, a desired buffer effect can be achieved in a process temperature (40 to 90 ℃) range against an impact generated during back grinding.

If the glass transition temperature of the core is higher than 40 ℃, the absorption capacity of the impact generated in the processing temperature range is limited, and thus the chip may be broken (CHIP CRACK), and if the glass transition temperature of the core is lower than-50 ℃, the particle shape may be easily deformed by the pressure at the time of the processing, and the impact absorption function may be problematic.

For example, the core may comprise one or more polyalkyl (meth) acrylates having a glass transition temperature in the range of-50 ℃ to 40 ℃. Preferably, the core may include one or more of polymethyl acrylate, polyethyl acrylate, cyclohexyl acrylate, benzyl acrylate, isopropyl acrylate, polybutyl methacrylate, polyhexamethylene methacrylate, polymethyl cyanoacrylate, and poly-2-cyanoethyl methacrylate, but is not limited thereto. More preferably, the core may comprise one or more of polymethyl acrylate and polybutyl methacrylate.

Preferably, the shell of the core-shell nanoparticle functions to form a hard structure, and is made of a material having a high glass transition temperature in order to ensure dispersibility in the binder layer.

The glass transition temperature of the shell of the core-shell nanoparticle may be 50 to 150 ℃, more preferably 60 to 130 ℃, and most preferably 80 to 130 ℃.

If the glass transition temperature of the shell is less than 50 ℃, there is a possibility that aggregation (aggregation) is caused by a decrease in particle dispersibility or that organic particles are deformed by heat generated when a processing step is performed, resulting in a decrease in recovery performance of the adhesive film under impact. If the glass transition temperature of the shell is more than 150 ℃, the cushioning effect may be deteriorated due to an increase in the hardness of the particles.

For example, the shell may comprise a polyalkyl (meth) acrylate having a glass transition temperature of 50 ℃ to 150 ℃. Preferably, the shell may include one or more of polymethyl methacrylate (PMMA), polyethyl methacrylate, polypropylene methacrylate, polybutyl methacrylate, polyisopropyl methacrylate, polyisobutyl methacrylate, and polycyclohexyl methacrylate, but is not limited thereto. More preferably, the shell may comprise polymethyl methacrylate.

The above-mentioned shell may be contained in an amount of 1 to 70 parts by weight, preferably 5 to 60 parts by weight, more preferably 10 to 50 parts by weight, relative to 100 parts by weight of the core-shell nanoparticle. If the content of the shell in the core-shell nanoparticle is less than 1 part by weight, the core cannot be sufficiently surrounded, and if it is more than 70 parts by weight, the surface protection effect of the wafer in the back grinding step is lowered, and if it is too much, the cushioning effect is lowered, and thus the restoring force of the adhesive film cannot be well maintained. Therefore, the balance of the buffer effect and the modulus can be maintained only when the above-mentioned shell satisfies the range of 1 to 70 parts by weight of the core-shell nanoparticle.

The core-shell nanoparticle may be contained in an amount of 0.1 to 20 parts by weight, more preferably 1 to 10 parts by weight, and most preferably 2 to 8 parts by weight, with respect to 100 parts by weight of the above-described second adhesive composition. If the content of the core-shell nanoparticle is less than 0.1 part by weight, the buffer effect of the nanoparticle may be insignificant, and if it is more than 20 parts by weight, uneven aggregation may occur due to a decrease in the binding force and a deterioration in the dispersibility of the particles, resulting in a halving of the buffer effect.

Preferably, the modulus of the second adhesive layer is 0.05 to 2MPa, more preferably 0.05 to 1MPa, in a temperature range of 60 to 90 ℃.

Preferably, the modulus of the second adhesive layer is 2MPa or less, since the use of a low modulus material is advantageous for further improving the cushioning effect characteristics. However, if the modulus is too low, the fluidity of the adhesive layer increases, and therefore, the thickness may be uneven due to the pressure applied during the back grinding process of the wafer, and therefore, the modulus of the second adhesive layer at high temperature is preferably 0.05MPa or more.

Preferably, the adhesive film of the present invention has a restoring force of 55% to 90%, more preferably 65% to 90%, most preferably 70% to 90%, as measured based on the following formula 1.

Formula 1: restoring force (%) = (1- (X _f/X₀)) ×100

In the above formula 1, X0 is a thickness 1/2 times the original thickness of the adhesive film, and X _f is a thickness at which the adhesive film is pressed when no force is applied to the adhesive film in the case of restoration after being held for 10 seconds at X ₀.

According to the adhesive film having a restoring force of 55% to 90%, the adhesive film is not deformed even under heat and pressure generated in the back grinding process of the wafer, and thus stable thickness uniformity of the wafer chip can be maintained. If the restoring force is less than 55%, the surface protection effect is insufficient when the wafer processing step is performed, and if the restoring force is more than 90%, the buffer effect is reduced, and the impact generated when the back grinding step is performed is transmitted to the wafer, so that the wafer may be broken.

In the present invention, the restoring force of the adhesive film is intended to measure the restoring force of the film including the adhesive layer, and the measurement is performed using a physical property tester (Texture Analyzer, ta.xt_plus), specifically as follows.

Measurement method

A test piece bonded in this order of polyethylene terephthalate (PET) film (50 μm)/adhesive film (length. Times.20 mm, width: 20mm, thickness: 60 μm)/polyethylene terephthalate film (50 μm) was fixed on a plate, then pressed at a high temperature (60 ℃) using a rectangular probe (probe) to a thickness of 1/2 times the original thickness of the adhesive film, namely X ₀ (unit: μm), at a speed of 300mm/min, and then held for 10 seconds, and thereafter restored at the same speed (300 mm/min) as the pressing speed, and when the thickness of the adhesive film pressed when a force of 0kPa was applied to the adhesive film was set to X _f (unit: μm), a restoring force (%) was calculated by the above formula 1.

The structure and operation of the present invention will be described in more detail below with reference to preferred embodiments of the present invention. This is a preferred illustration of the invention and should not be construed as limiting the invention in any way.

Preparation example

Preparation example 1: second adhesive layer Forming composition ("M1")

A mixture obtained by mixing 42 parts by weight of butyl acrylate, 10 parts by weight of ethylhexyl acrylate, 30 parts by weight of methyl acrylate, 5 parts by weight of 2-hydroxyethyl acrylate, 13 parts by weight of acrylic acid, 0.05 part by weight of azobisisobutyronitrile, 100 parts by weight of ethyl acetate was polymerized under a nitrogen atmosphere for 6 hours at a temperature of 60 ℃ to obtain an acrylic resin polymerization liquid a having a weight average molecular weight of 80 ten thousand.

To 100 parts by weight of the acrylic resin polymerization liquid a, 2 parts by weight of an isocyanate-based curing agent (trade name "cornonate C" manufactured by japan polyurethane industry co., ltd.) was added, thereby obtaining a second adhesive layer-forming composition (labeled "M1").

Preparation example 2: second adhesive layer Forming composition ("M2")

A mixture obtained by mixing 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, 100 parts by weight of ethyl acetate was polymerized under a nitrogen atmosphere for 6 hours at a temperature of 60 ℃ to obtain an acrylic resin polymer liquid B having a weight average molecular weight of 60 ten thousand.

To 100 parts by weight of the above-mentioned acrylic resin polymerization liquid B, 3 parts by weight of an isocyanate-based curing agent (trade name "cornonate C" manufactured by japan polyurethane industry co., ltd.) was added, thereby obtaining a second adhesive layer-forming composition (labeled "M2").

Preparation example 3: first adhesive layer Forming composition ("A1")

A reactor provided with a cooling device in such a manner that nitrogen was circulated and the temperature was adjusted was charged with a monomer mixture composed of 27g of Butyl Acrylate (BA), 48g of Methyl Acrylate (MA) and 25g of hydroxyethyl acrylate (HEA).

Next, 100 parts by weight of ethyl acetate (EAc) was put as a solvent into 100 parts by weight of the above monomer mixture, nitrogen was injected into the above reactor to remove oxygen, and the mixture was thoroughly mixed at 30 ℃ for 30 minutes or more. Next, the temperature was maintained at 50℃and after charging azobisisobutyronitrile having a concentration of 0.1 part by weight as a reaction initiator and initiating a reaction, polymerization was performed for 24 hours to prepare a first reactant.

24.6 Parts by weight of methacryloyloxyethyl isocyanate (MOI) and 1% by weight of catalyst (DBTDL: dibutyl tin dilaurate) relative to the MOI were prepared and reacted at 40℃for 24 hours to obtain an acrylic polymer C having a weight average molecular weight of 50 ten thousand.

To 100 parts by weight of the above-mentioned acrylic polymer C, 0.1 part by weight of a photoinitiator (Irgacure) 184 (trade name manufactured by BASF) as a photopolymerization initiator was blended, and 2 parts by weight of an isocyanate-based curing agent (trade name "cornate C" manufactured by japan polyurethane industry co., ltd.) was added to obtain a first adhesive layer-forming composition (labeled "A1").

Preparation example 4: core-shell nanoparticles ("b 1")

The core was formed of polymethyl acrylate (PMA, tg:10 ℃ C.), and the shell was formed of polymethyl methacrylate (PMMA, tg:105 ℃ C.), thereby constituting a core-shell structure, and in the core-shell nanoparticle, the shell was 40 parts by weight with respect to 100 parts by weight of the core-shell nanoparticle, and the average particle diameter was 230nm.

Preparation example 5: core-shell nanoparticles ("b 2")

The core is formed of polymethyl acrylate (PMA), and the shell is formed of polymethyl methacrylate (PMMA), thereby constituting a core-shell structure, and in the core-shell nanoparticle, the shell is 30 parts by weight with respect to 100 parts by weight of the core-shell nanoparticle, and the average particle diameter is 130nm.

Examples

Example 1

The first adhesive layer-forming composition ("A1") in preparation example 3 was coated on a release-treated polyethylene terephthalate (PET) film (thickness 50 μm) so that the thickness of the first adhesive layer reached 20 μm, and then a film having a first adhesive layer with a total thickness of 120 μm was produced by bonding a polyethylene terephthalate base film (thickness 50 μm) having a primer layer formed thereon.

Next, the core-shell nanoparticle B1 in preparation example 4 was added and mixed to the second binder layer-forming composition ("M2") in preparation example 2 in such a manner that the ratio between the acrylic resin polymerization liquid B and the core-shell nanoparticle B1 in preparation example 4 reached 100 parts by weight to 4 parts by weight, and then coated on a polyethylene terephthalate film (thickness 20 μm) at a thickness of 20 μm, thereby producing a film having a second binder layer with a total thickness of 40 μm.

The film having the first adhesive layer and the film having the second adhesive layer were joined to each other to prepare a composite film having a total thickness of 160 μm, and the wafer processing adhesive film was finally prepared by using a protective sheet.

Example 2

The preparation was performed in the same manner as in example 1, except that the second adhesive layer-forming adhesive composition ("M1") in preparation example 1 was used as the second adhesive layer instead of the second adhesive layer-forming adhesive composition ("M2") in preparation example 2, and the "b2" in preparation example 5 was used as the core-shell nanoparticle instead of the "b1" in preparation example 4.

Example 3

The preparation was performed in the same manner as in example 1, except that "M2" was used and a coating was performed on a polyethylene terephthalate film (thickness of 20 μm) at a thickness of 50 μm to form a second adhesive layer having a total thickness of 70 μm.

Example 4

The preparation was performed in the same manner as in example 2, except that "M1" was used and coating was performed on a polyethylene terephthalate film (thickness of 20 μm) at a thickness of 50 μm to form a second adhesive layer having a total thickness of 70 μm and so that the content of "b2" in preparation example 5 as core-shell nanoparticles was 2 parts by weight.

Example 5

The preparation was performed in the same manner as in example 1, except that "M2" was used and coating was performed on a polyethylene terephthalate film (thickness of 20 μm) at a thickness of 80 μm to form a second adhesive layer having a total thickness of 100 μm, and 8 parts by weight of "b2" in preparation example 5 was used as the core-shell nanoparticle instead of "b1" in preparation example 4.

Example 6

The preparation was performed in the same manner as in example 2, except that "M1" was used and coating was performed on a polyethylene terephthalate film (thickness of 20 μm) at a thickness of 80 μm to form a second adhesive layer having a total thickness of 100 μm and 8 parts by weight of the core-shell nanoparticle "b2" in preparation example 5 was used.

Comparative example 1

The preparation was performed in the same manner as in example 4, except that the core-shell nanoparticles were not included in the second binder layer.

Comparative example 2

Preparation was performed in the same manner as in example 3, except that "b1" in preparation example 4 was used as the core-shell nanoparticle instead of "b2" in preparation example 5 and the content thereof was 25 parts by weight.

Experimental example

Experimental example 1: determination of modulus of adhesive film (60 ℃ C., 90 ℃ C.)

The modulus at a temperature of from-20℃to 120℃was measured on a sample having a size of 8mm in diameter by 1mm in thickness obtained by laminating an adhesive layer of a single layer formed from a solution of the second adhesive layer forming composition used in examples and comparative examples using a modulus measuring apparatus Rheometer (Rheometer, american thermal analysis instruments, inc., TA instruments), ARES-G2, and the moduli at temperatures of 60℃and 90℃were recorded and are shown in Table 1.

Experimental example 2: restoring force

The restoring force of the adhesive film was measured by using a physical property tester (Texture Analyzer, ta.xt_plus) and calculated based on the following formula 1, and a specific measurement method is as follows.

Formula 1: restoring force (%) = (1- (X _f/X₀)) ×100

Measurement method

The restoring force of the adhesive films in examples 1 to 6 and comparative examples 1 to 2 was measured according to the above formula 1 and measurement method and is shown in table 1.

Experimental example 3: wafer grinding test (thickness uniformity)

The adhesive films of examples 1 to 6 and comparative examples 1 to 2 were attached to the semiconductor circuit surface, and then a wafer of 725 μm was back-polished to a thickness of 100 μm. The adhesive film was removed by irradiating UV A300 mJ/cm ², and then the average thickness uniformity of 10 points within the polished wafer was compared. If the average value of the thickness variation at each point is 4 μm or less, the value is evaluated as "O" (good), and if it is 6 μm or more, the value is evaluated as "X" (bad).

TABLE 1

As shown in table 1 above, examples 1 to 6 including core-shell nanoparticles have excellent recovery force and thickness uniformity compared to comparative example 1. In comparative example 2, the modulus value of the second adhesive layer was more than 2MPa, the restoring force was more than 90%, the cushioning property was insufficient, and it was difficult to measure the thickness uniformity.

The present invention has been described above with reference to the accompanying drawings, but the present invention is not limited to the embodiments and drawings disclosed in the present specification, and it is obvious that various modifications can be made by one skilled in the art to which the present invention pertains within the scope of the technical ideas of the present invention. Also, it should be understood that the operational effects of the structure of the present invention, which are not explicitly described in the course of describing the embodiments of the present invention, include effects that can be predicted by the corresponding structure.

Claims

1. An adhesive film for wafer processing, characterized in that,

Comprising the following steps:

A multi-layer substrate comprising 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,

The second adhesive layer is made of a second adhesive composition comprising an adhesive resin and core-shell nanoparticles,

The core of the core-shell nanoparticle is polyalkyl (methyl) acrylate with the glass transition temperature reaching-50 ℃ to 40 ℃,

The shell of the core-shell nanoparticle is polyalkyl (methyl) acrylate with the glass transition temperature reaching 50-150 ℃,

Comprising 2 to 8 parts by weight of core-shell nanoparticles relative to 100 parts by weight of the binder resin of the second binder composition,

The core-shell nanoparticle comprises 1 to 70 parts by weight of the shell per 100 parts by weight of the core-shell nanoparticle.

2. The wafer processing adhesive film according to claim 1, wherein the core-shell nanoparticles have an average particle diameter of 5nm to 400nm.

3. The adhesive film for wafer processing according to claim 1, wherein the modulus of the second adhesive layer is 0.05 to 2MPa at a temperature ranging from 60 to 90 ℃,

Wherein the modulus is obtained by measuring the modulus at a temperature of-20 ℃ to 120 ℃ in a sample having a diameter of 8mm by 1mm in thickness by a modulus measuring device under a condition of 1 Hz.

4. The wafer processing adhesive film according to claim 1, wherein,

The adhesive film has a restoring force of 55% to 90% as measured according to the following formula 1,

Formula 1: restoring force (%) = (1- (X _f/X₀)) ×100

In the above formula 1, X ₀ is a thickness 1/2 times the original thickness of the adhesive film, and X _f is a thickness at which the adhesive film is pressed when no force is applied to the adhesive film in the case of recovery after holding for 10 seconds with X ₀.

5. The adhesive film for wafer processing according to claim 1, wherein the modulus of the lower substrate layer and the upper substrate layer is 1000MPa or more at a temperature of 23 ℃.

6. The adhesive film for wafer processing according to claim 1, wherein the lower substrate layer and the upper substrate layer each contain one or more selected from the group consisting of polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate, wholly aromatic polyester, polyimide, polyamide, polycarbonate, polyacetal, modified polyphenylene oxide, polyphenylene sulfide, polysulfone, polyether ketone, and biaxially oriented polypropylene.

7. The wafer processing adhesive film according to claim 6, wherein the lower substrate layer and the upper substrate layer are made of polyethylene terephthalate.

8. The wafer processing adhesive film according to claim 1, wherein the adhesive resin of the second adhesive layer comprises a thermosetting acrylic adhesive resin.

9. The adhesive film for wafer processing according to claim 1, wherein a primer layer is additionally formed 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.