TWI808868B - Adhesive film for wafer processing - Google Patents

Abstract

An adhesive film for wafer processing of the present invention comprises a multilayer base material including an upper base material layer and a lower base material layer; a first adhesive layer disposed on the upper base material layer; and a second adhesive layer disposed between the upper base material layer and the lower base material layer. The adhesive film for wafer processing meets a tensile strength in the range of 70 to 150 MPa, and reduces or eliminates stress (shear stress) generated in the back surface grinding process by adjusting the fluidity of the first adhesive layer and the second adhesive layer, so as to prevent the wafer from damaging and inhibit curling. Moreover, the processability is excellent by preventing the movement or collision of the cut semiconductor chip and the occurrence of cracks.

Description

Adhesive film for wafer processing

The present invention relates to an adhesive film used to protect the surface of a wafer during wafer back grinding (wafer back grinding or wafer lapping or wafer thinning). More specifically, the present invention relates to an adhesive film for wafer back grinding that is excellent in processability by reducing or eliminating stress generated during wafer back grinding.

With the development of technology in recent years, semiconductor chips are required to be miniaturized, denser, and thinner, and therefore, wafers are also required to be thinner. A typical method for thinning wafer chips is to achieve thinning by grinding the backside of the wafer to reduce the thickness.

In this back grinding process, shear and compressive stress (vibration, impact, etc.) are generated as the temperature rises. To protect the surface of the wafer, the wafer back grinding process is performed with an adhesive film for wafer processing attached.

In general, known wafer backside grinding process methods are mainly applied: the conventionally used method of first grinding the backside of the wafer, and then dividing the thinned wafer according to the chip size (pre-grinding method), and the recent method of dicing chips by pre-forming grooves in the wafer and grinding the backside ("pre-dicing method" or "DBG (DBG) method").

When the back surface is ground by the pre-grinding method, the adhesive film for wafer back grinding is typically applied in the form of a soft base material and an adhesive layer adhered to the wafer on one side of the base material, or a hard base material and an adhesive layer adhered to the wafer on one side of the base material, and a soft buffer layer capable of cushioning impact on the opposite side of the adhesive layer. However, if a soft substrate is used or a hard substrate and a soft buffer layer are used as the substrate layer, the overall strength of the adhesive film for wafer backgrinding will be reduced, and when the adhesive film for wafer backgrinding is adhered to the wafer, residual stress will be left on the film because the applied tension is not released. In the state where such stress remains, when the wafer is thinned by the pre-polishing method, curling occurs on the polished wafer along the direction of the adherent adhesive film due to the residual stress, and then when the wafer is divided, it cannot be adsorbed to the jig for fixing the wafer, and the division process cannot be performed. Furthermore, in cases where warpage is severe, the wafer itself may break.

On the other hand, when the back surface is ground by the pre-dicing method, shear stress generated during the grinding process is applied after dicing the chip. Chips may move due to the fluidity of the adhesive layer under the influence of shear stress, and due to the movement of the chips, chips may collide with each other to generate crack defects.

In particular, the "Stealth Dicing Before Grinding (SDBG, Stealth DBG) process," which uses a laser beam to divide a wafer into individual device chips, has been introduced in recent years. As the distance between chips (also called "kerf width") after chip dicing becomes very narrow, it has become technically important to suppress chip movement.

The problem to be solved by the invention

An object of the present invention is to provide an adhesive film for wafer processing which is excellent in protecting the surface of the wafer during the wafer back grinding process (buffering effect), and at the same time prevents damage to the wafer by reducing or eliminating the stress (shear stress) generated during the process, suppresses curling (curl) generated along the direction of the adhesive film on the wafer due to residual stress, and prevents movement or collision of the diced semiconductor chip (chip) and the phenomenon of cracking (crack), so that the workability is excellent.

The purpose of the present invention is not limited to the above-mentioned purpose, and other unmentioned purposes and advantages of the present invention can be understood through the following description, and can be more clearly understood through the embodiments of the present invention. Furthermore, it can be seen that the objects and advantages of the present invention can be achieved by means and combinations thereof shown in the claims of the invention.

technical means to solve problems

The adhesive film for wafer processing according to the embodiment of the present invention for solving the above-mentioned technical problems may include: a multi-layer base material, including an upper base material layer and a lower base material layer; a first adhesive layer disposed on the upper base material layer; and a second adhesive layer disposed between the upper base material layer and the lower base material layer.

Formula 1: 0.2≤C1/C2≤1.4

In the above formula 1, C1 is the creep value (μm) of the first adhesive layer under the temperature condition of 30°C, and C2 is the creep value (μm) of the second adhesive layer under the temperature condition of 30°C.

Formula 2: 0.2≤C1'/C2'≤1.4

In the above formula 2, C1' is the creep value (μm) of the first adhesive layer at a temperature of 60°C, and C2' is the creep value (μm) of the second adhesive layer at a temperature of 60°C.

In the above formula 1 and formula 2, the above C1 and C1' may be 30 µm to 200 µm, and C2 and C2' may be 50 µm to 350 µm.

The sum of the thicknesses of the first adhesive layer and the second adhesive layer may be 20 μm to 150 μm.

The above-mentioned first adhesive layer can be formed by an ultraviolet curable adhesive composition.

The above-mentioned second adhesive layer can be formed from a thermosetting adhesive composition.

The shear storage modulus of the second adhesive layer under the temperature conditions of 30° C. and 60° C. may be 0.02˜1.0 MPa.

The above-mentioned lower base material layer and upper base material layer may respectively include more than one selected from the group consisting of polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate, wholly aromatic polyester, polyimide, polyamide, polycarbonate, polyacetal, modified polyphenylene ether, polyphenylene sulfide, polyether ketone, and biaxially oriented polypropylene. More preferably, they may be formed of polyethylene terephthalate material. .

At least one of the upper surface of the upper base material layer, the lower surface of the upper base material layer, and the upper surface of the lower base material layer may further include a primer layer.

Efficacy compared to prior art

When the adhesive film for wafer processing of the present invention is applied to the back grinding process of a wafer, the protection effect (cushion effect) of the surface of the wafer is excellent.

The adhesive film for wafer processing of the present invention can prevent damage to the wafer by reducing or suppressing the stress generated during the back grinding process.

The adhesive film for wafer processing of the present invention can suppress the curling (curl) generated along the direction of the adhesive film on the wafer due to residual stress, and can improve the processability of the wafer and the quality of the prepared semiconductor chip by preventing the movement or collision of the cut semiconductor chip (chip) and the phenomenon of cracks.

The effects of the present description are not limited to the effects mentioned above, and other effects not mentioned can be clearly understood by those skilled in the art from the following description. Hereinafter, the above-mentioned effects and specific effects of the present invention will be described while describing specific details for implementing the present invention.

The foregoing objects, features, and advantages will be described in detail with reference to the accompanying drawings, whereby those skilled in the art to which the present invention pertains can easily implement the technical idea of the present invention. In describing the present invention, if it is judged that the detailed description of the known technology related to the present invention may unnecessarily obscure the gist of the present invention, the detailed description will be omitted. Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings. In the drawings, the same reference numerals are used for the same or similar structural elements.

In this specification, an arbitrary structure arranged on "above (or below)" a structural element or "above (or below)" a structural element not only means an arrangement where an arbitrary structure is in contact with the upper surface (or lower surface) of the above-mentioned structural element, but also means that other structures may be interposed between the above-mentioned structural element and any structure arranged on (or under) the above-mentioned structural element.

Singular expressions used in this specification include plural expressions unless otherwise explicitly mentioned in this specification. In this application, terms such as "consisting of" or "comprising" should not be interpreted as necessarily including all the various structural elements described in the specification, but should be interpreted as not including some of the structural elements, or may also include additional structural elements.

In this specification, terms such as "one side", "another side", and "both sides" are used to distinguish a certain structural element from other structural elements, and the structural elements are not limited to the above terms.

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

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

FIG. 1 is a cross-sectional view schematically showing a wafer processing adhesive film 100 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 configured on the upper substrate layer 112 of the multilayer substrate; and a second adhesive layer 115 configured between the above-mentioned upper substrate layer 112 and the lower substrate layer 111.

The first adhesive layer 120 can be adhered to the surface of the wafer to fix the wafer, and the second adhesive layer 115 can be disposed between the upper base material layer 112 and the lower base material layer 111, and serves as a buffer layer for alleviating the vibration and impact applied during back grinding.

In particular, as a result of intensive research by the present inventors, it has been confirmed that the tensile strength of the wafer processing adhesive film 100 can be increased by forming the upper base material layer 112 and the lower base material layer 111 as rigid base materials, thereby suppressing the residual stress during the back grinding process, and the second adhesive layer 115 can alleviate the impact generated during the back grinding process. However, if the tensile strength of the wafer processing adhesive film 100 is too high, it may become too hard to be used in the back grinding process. Considering this point, the tensile strength of the wafer processing adhesive film 100 of the present invention is preferably 70-150 MPa, more preferably 70-120 MPa, most preferably 70-100 MPa.

Moreover, in the present invention, it is also confirmed through experiments that the problem of movement of the semiconductor chips that are cut due to stress during the back grinding process and the phenomenon of cracks caused by collisions between semiconductor chips can be solved by properly adjusting the flow degree of the first adhesive layer 120 and the second adhesive layer 115, thereby significantly improving manufacturability.

Specifically, as a means for adjusting the fluidity of the first adhesive layer 120 and the second adhesive layer 115, the respective creep values (unit: μm) of the first adhesive layer 120 and the second adhesive layer 115 can be measured under temperature conditions of 30° C. and 60° C. (the highest temperature raised during the back grinding process), so that these ratios fall within a specific range. Preferably, the ranges of the following formulas 1 and 2 can be satisfied.

Formula 1: 0.2≤C1/C2≤1.4

In the above formula 1, C1 is the creep value (μm) of the first adhesive layer under the temperature condition of 30°C, and C2 is the creep value (μm) of the second adhesive layer under the temperature condition of 30°C.

Formula 2: 0.2≤C1'/C2'≤1.4

In the above formula 2, C1' is the creep value (μm) of the first adhesive layer at a temperature of 60°C, and C2' is the creep value (μm) of the second adhesive layer at a temperature of 60°C.

In the present invention, the adhesive composition used to form the adhesive layer of the measurement object is coated on polyethylene terephthalate (PET), dried at a temperature of 100°C for 4 minutes, and aged in a constant temperature and humidity device maintained at a temperature of 40°C and a relative humidity of 50%, to prepare an adhesive layer sample for measuring the creep value by aging for 3 days. Afterwards, the prepared adhesive layer sample was cut into a size of 15mm×120mm, and it was adhered to the adherend (stainless steel (SUS), glass (Glass), etc.) for creep measurement, so that the adhesion area was 15mm×15mm, and using a universal physical property analyzer (device name: TA.XT Plus_Stable Micro Systems), at 30°C and 60°C, when a force of 1.5kg was applied for 1000 seconds, the adhesion The length (μm) by which the layer deforms along the direction of the applied force is taken as the amount of creep.

Moreover, regarding the values of C1, C2, C1' and C2' in the above formula 1 and formula 2, preferably, the above-mentioned C1 and C1' related to the first adhesive layer may be 30-200 μm, more preferably, 30-160 μm, most preferably, 70-160 μm. And, preferably, the above-mentioned C2 and C2' related to the second adhesive layer may be 50-350 μm, more preferably, 50-320 μm, most preferably, 80-320 μm.

When the values of C1, C2, C1' and C2' in the above formulas 1 and 2 are less than the lower limit, it means that the cohesive force of the adhesive layer itself is very high. Therefore, the adhesion to the adherend is reduced, and the resistance to shear stress is reduced. Furthermore, when C2 and C2' related to the second adhesive layer are less than the lower limit, the shear storage modulus of the second adhesive layer becomes too high, and there is a problem that the function as a buffer layer cannot be fully exerted. On the other hand, when it is greater than the upper limit When the value is , the fluidity of the bonding layer increases, which can cause the movement of the chip and the resulting crack defect problem.

The thicknesses of the first adhesive layer 120 and the second adhesive layer 115 of the present invention are not limited, but may have a thickness within a range of 10˜100 μm, respectively.

Moreover, the sum of the thicknesses of the first adhesive layer 120 and the second adhesive layer 115 may be 20-150 μm, more preferably, 80-150 μm. When the sum of the thicknesses of the first adhesive layer 120 and the second adhesive layer 115 is less than 20 μm, there may be a problem of crack defects due to the inability to absorb the vibration and impact caused by the shear stress. When the sum of the thicknesses of the first adhesive layer 120 and the second adhesive layer 115 is greater than 150 μm, there may be a problem of movement of the chip due to an increase in creep and thus generation of crack defects.

Each layer of the adhesive film for wafer backgrinding will be described in detail below.

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 base material layer 112 , and the second adhesive layer 115 is disposed between the lower base material layer 111 and the upper base material layer 112 . In the adhesive film for wafer processing of the present invention, the multilayer substrate has a sandwich 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 formed of a material having a high tensile elastic modulus. More specifically, the lower base material layer 111 and the upper base material layer 112 may have a tensile modulus of 1000 MPa or higher, for example, 1200 MPa or higher, 1500 MPa or higher, 2000 MPa or higher, and most preferably 3000 MPa or higher.

When the tensile elastic modulus of the upper substrate layer 112 and the lower substrate layer 111 is relatively low, less than 1000 MPa, the semiconductor chip may collide during the back grinding process due to the low support force of the wafer or the cut semiconductor chip.

In the present invention, not only the upper substrate layer 112 on the bonding side of the wafer, but also the lower substrate layer 111 is also suitable for rigid substrates, so that the tensile strength of the adhesive film for wafer processing can meet 70 MPa or more. When the tensile strength is 70 MPa or more, the manufacturability can be improved by being resistant to strong stress in the back grinding process.

The lower substrate layer 111 and the upper substrate layer 112 may respectively include polyesters selected from polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polybutylene terephthalate (PBT), wholly aromatic polyesters, polyimide (PI), polyamide (PA), polycarbonate (PC), polyacetal, modified polyphenylene ether, polyphenylene sulfide, polyphenol, polyether ketone, bidirectional One or more of the group consisting of stretched polypropylene (Oriented Polypropylene).

Preferably, the lower substrate layer 111 and the upper substrate layer 112 may be formed of the same material. For example, the lower base material layer 111 and the upper base material layer 112 may be formed of a polyethylene terephthalate (PET) material having a tensile modulus of 3000 MPa or more.

The lower substrate layer 111 and the upper substrate layer 112 may have the same thickness, but not limited thereto. The lower substrate layer 111 and the upper substrate layer 112 may respectively have a thickness of about 10˜150 μm. On the other hand, in the present invention, since the lower base material layer 111 and the upper base material layer 112 have a high tensile modulus of elasticity, the lower base material layer 111 and the upper base material layer 112, especially when the thickness of the upper base material layer 112 is too thick, may be easily affected by the impact generated during the back grinding process. For this reason, preferably, the thicknesses of the lower base material layer 111 and the upper base material layer 112 can be set to be about 150 μm or less.

On the other hand, the lower substrate layer 111 and/or the upper substrate layer 112 may include a small amount of various additives, such as coupling agents, plasticizers, antistatic agents, antioxidants, etc., as required.

first bonding layer

In FIG. 1 , the first bonding layer 120 is a part bonded to the wafer. The first adhesive layer 120 is not particularly limited as long as it has appropriate adhesiveness under normal temperature conditions, and known ultraviolet curable adhesive compositions can be applied in various ways.

For example, the first adhesive layer is formed of an adhesive composition containing acrylic, polyurethane, rubber, silicon adhesive resin, etc., preferably, can be formed by an adhesive composition (acrylic adhesive composition) containing ultraviolet curing acrylic adhesive resin.

The above ultraviolet curable acrylic adhesive resin can be prepared by polymerizing a monomer containing at least an alkyl (meth)acrylate. Examples of the monomer include methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, n-butyl (meth)acrylate, n-pentyl (meth)acrylate, n-hexyl (meth)acrylate, n-heptyl (meth)acrylate, n-octyl (meth)acrylate, isooctyl (meth)acrylate, n-nonyl (meth)acrylate, n-decyl (meth)acrylate, (meth) Lauryl acrylate, 2-ethylhexyl acrylate, 4-methyl-2-pentyl acrylate, etc., and alkyl (meth)acrylate may be contained by 1 type or 2 or more types.

According to need, in order to adjust the adhesive properties of the acrylic adhesive composition, it may be polymerized by further including a functional group-containing monomer in addition to the alkyl (meth)acrylate monomer. Examples of the above-mentioned functional group include hydroxyl group, carboxyl group, amino group, epoxy group and the like.

Hydroxyl-containing monomers include hydroxyalkyl (meth)acrylates, such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 3-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, etc., or unsaturated alcohols, such as vinyl alcohol, allyl alcohol, etc.

When the acrylic adhesive composition is polymerized by including a functional group-containing monomer, it can also be prepared by further reacting a compound having a photopolymerizable unsaturated group. The compound having an unsaturated group is a compound having a substituent capable of bonding to a functional group in the acrylic adhesive composition and a photopolymerizable unsaturated group. The photopolymerizable unsaturated group may, for example, be a (meth)acryl group, a vinyl group, an allyl group or a vinylbenzyl group, preferably a (meth)acryl group.

In addition, in the compound having an unsaturated group, the substituent that can be bonded to the functional group includes isocyanate, glycidyl group, and the like. For example, the compound having an unsaturated group includes (meth)acryloxyethyl isocyanate, (meth)acryl isocyanate, glycidyl (meth)acrylate, and the like.

The first adhesive composition may further contain one or more of a crosslinking agent and a photopolymerization initiator.

The UV curing crosslinking agent includes isocyanate crosslinking agents, such as toluene diisocyanate, hexamethylene diisocyanate, etc., or epoxy crosslinking agents, such as ethylene glycol glycidyl ether, etc., or aziridine crosslinking agents, such as hexa[1-(2-methyl)-aziridinyl]triphosphotriazine, etc., or chelate crosslinking agents, such as aluminum chelate, etc.

Photopolymerization initiators include benzoin compounds, acetophenone compounds, acyl phosphine oxide compounds, titanocene compounds, thioxanthone compounds, and peroxide compounds. Examples include 1-hydroxycyclohexyl phenyl ketone, 2-hydroxy-2-methyl-1-phenyl-propan-1-one, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzyl phenylene sulfide, tetramethylthiuram monosulfide, azobisisobutyronitrile, dibenzyl, diacetyl, 8- Chloranthraquinone, bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide, etc.

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

FIG. 2 is a cross-sectional view schematically showing a wafer processing adhesive film 100 according to an embodiment of the present invention.

Referring to FIG. 2 , a primer layer 113 may further be included on the upper surface of the upper substrate layer 112 of the multilayer substrate. The primer layer 113 can be used to improve the adhesion between the first adhesive layer 120 and the multi-layer substrate 110 .

The primer layer 113 may be formed as a separate layer on the upper face of the upper substrate layer 112 , that is, on the face where the first adhesive layer 120 is formed. As another example, the primer layer 113 may be formed by modifying the upper surface of the upper substrate layer 112 .

2 shows an example in which the primer layer 113 is formed on the upper surface of the upper substrate layer 112, but 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 , a release film disposed on the upper surface of the first adhesive layer and bonded by the above-mentioned adhesive layer may also be included. A release treatment may be performed on one side of the release film. The above-mentioned release treatment can be used without limitation as long as it is a material commonly used for release treatment in this field. For example, silicone is preferably used for release treatment.

Second adhesive layer

In the present invention, the second adhesive layer 115 is an adhesive layer disposed between the upper base material layer 112 and the lower base material layer 111, and can be used as a buffer layer or a shock absorbing layer with a high buffering effect during wafer processing to protect the wafer surface.

The second adhesive layer of the present invention can be formed of a thermosetting resin composition, and various known thermosetting adhesive compositions can be used. Preferably, an adhesive composition comprising a thermosetting acrylic adhesive resin can be used.

The above-mentioned thermosetting acrylic adhesive resin can be prepared by polymerizing a monomer containing an alkyl (meth)acrylate having 4 or more carbon atoms, and can be polymerized by further including a monomer containing a functional group in addition to the alkyl (meth)acrylate monomer in order to adjust the adhesive properties if necessary. Examples of the above-mentioned functional group include hydroxyl group, carboxyl group, amino group, epoxy group and the like.

Acrylate compounds that can be used in thermosetting acrylic adhesive compositions include (meth)acrylates, alkyl (meth)acrylates such as alkyl (meth)acrylates with an alkyl group having 4 or more carbon atoms, non-urethane polyfunctional (meth)acrylates, etc., but are not limited thereto.

The above-mentioned second bonding composition may also include a thermosetting agent, such as an isocyanate thermosetting agent, a carbodiimide thermosetting agent, an oxazoline thermosetting agent, an epoxy thermosetting agent, an aziridine thermosetting agent and a peroxide thermosetting agent, etc., but is not limited thereto.

With respect to 100 parts by weight of the adhesive resin of the second adhesive composition, the thermosetting agent may be included in an amount of 2 parts by weight or less, but is not necessarily limited thereto.

On the other hand, since the second adhesive layer 115 functions as a buffer layer, the lower the shear storage modulus, the better the buffer effect, thereby effectively protecting the surface of the wafer. On the contrary, in the case of a buffer layer having a low shear storage modulus, there may be a problem that the buffer layer flows under high temperature conditions or has non-uniform thickness due to temperature rise in the back grinding process. Considering this problem, preferably, the shear storage modulus of the second adhesive layer 115 at the temperature of 30° C. and 60° C. may be 0.02-1.0 MPa, more preferably 0.02-0.5 MPa, most preferably 0.02-0.2 MPa.

The above-mentioned second adhesive layer 115 may have a glass transition temperature (Tg) below 10°C, preferably between -35°C and 10°C, more preferably between -30°C and 8°C. Due to the low glass transition temperature of the second adhesive layer, it can have a strong adhesive force. Therefore, even if the temperature of the wafer back grinding process is raised from normal temperature to a maximum of 90° C., the separation of the upper substrate layer 112 and the lower substrate layer 111 can be prevented. However, with too low a glass transition temperature below -35° C. temperature conditions, the second bonding composition flows due to the heat and pressure that may be generated during the wafer backgrinding process, contaminating the wafer.

Hereinafter, the structure and function 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 should not be construed as limiting the present invention in any sense. Contents not described here can be sufficiently technically deduced by a person skilled in the art, and therefore descriptions thereof are omitted.

Preparation Example 1: Preparation of Adhesive Composition A1

A monomer mixture consisting of 27 grams of n-butyl acrylate (BA), 48 grams of methyl acrylate (MA) and 25 grams of hydroxyethyl acrylate (HEA) was put into the reactor, and a cooling device was set in the reactor to make the nitrogen reflux and adjust the temperature easily.

Next, put 100 parts by weight of ethyl acetate (EAc) as a solvent into 100 parts by weight of the above-mentioned monomer mixture, and in order to remove oxygen in the above-mentioned reactor, inject nitrogen gas and mix thoroughly at a temperature of 30° C. for more than 30 minutes. Thereafter, the temperature was raised to 50° C. and maintained, and azobisisobutyronitrile was added at a concentration of 0.1 parts by weight as a reaction initiator to start the reaction, and then polymerized for 24 hours to prepare a first reactant.

24.6 parts by weight of 2-methacryloxyethyl isocyanate (MOI) and 1 part by weight of catalyst (dibutyltin dilaurate (DBTDL: dibutyl tin dilaurate)) relative to MOI were mixed with the above-mentioned first reactant, and the acrylic resin with a weight average molecular weight of 600,000 was obtained by reacting at a temperature of 40° C. for 24 hours.

As a photoinitiator, 0.1 parts by weight of Irgacure 184 (manufactured by BASF, trade name) was mixed with the polymerization liquid (acrylic polymer, content: 100 parts by weight) obtained through the above operation, and 2 parts by weight of isocyanate crosslinking agent (Nippon Polyurethane Kogyo Co., Ltd. (Nippon Polyurethane Kogyo Co., Ltd.) prepared, trade name "Coronate C") was added to obtain adhesive composition A1.

Preparation Example 2: Preparation of Adhesive Composition A2

In the preparation process of the adhesive composition A1, except that the monomer mixture consisting of 45 g of n-butyl acrylate (BA), 30 g of methyl acrylate (MA) and 25 g of hydroxyethyl acrylate (HEA) was changed, and the isocyanate crosslinking agent (“Coronate C”) was changed to 1 part by weight, it was prepared in the same manner as the adhesive composition A1.

Preparation Example 3: Preparation of Adhesive Composition B1

A monomer mixture consisting of 33 grams of n-butyl acrylate (BA), 50 grams of methyl acrylate (MA), 10 grams of hydroxyethyl acrylate (HEA) and 10 grams of 2-ethylhexyl acrylate (EHA) was put into the reactor, and a cooling device was set in the reactor to make the nitrogen reflux and adjust the temperature easily.

Next, put 100 parts by weight of ethyl acetate (EAc) as a solvent into 100 parts by weight of the above-mentioned monomer mixture, and in order to remove oxygen in the above-mentioned reactor, inject nitrogen gas and mix thoroughly at a temperature of 30° C. for more than 30 minutes. Thereafter, the temperature was raised to 50° C. and maintained, and azobisisobutyronitrile was added at a concentration of 0.1 parts by weight as a reaction initiator to start the reaction, and then polymerized for 24 hours to obtain an acrylic resin with an average molecular weight of 500,000.

1.5 parts by weight of an isocyanate crosslinking agent (manufactured by Nippon Polyurethane Kogyo Co., Ltd., trade name "Coronate C") was added to the polymerization liquid (acrylic polymer, content: 100 parts by weight) obtained through the above operations to obtain a bonding composition B1.

Preparation Example 4: Preparation of Adhesive Composition B2

In the preparation process of the adhesive composition A1, except that the monomer mixture consisting of 50 g of n-butyl acrylate (BA), 20 g of methyl acrylate (MA), 8 g of hydroxyethyl acrylate (HEA) and 22 g of 2-ethylhexyl acrylate (EHA) was changed, and the isocyanate crosslinking agent ("Coronate C") was changed to 0.5 parts by weight, it was prepared in the same manner as the adhesive composition A1.

Example 1

The adhesive composition A1 of Preparation Example 1 was coated on a release-treated PET (polyethylene terephthalate film with a thickness of 50 μm) at a thickness of 30 μm, and then a composite film having a first adhesive layer with a thickness of 130 μm was prepared by bonding a biaxially oriented PET film (upper substrate layer) with a thickness of 50 μm.

Next, the adhesive composition B1 of Preparation Example 3 was coated with a thickness of 50 μm on a biaxially oriented PET film (lower substrate layer) with a thickness of 25 μm to prepare a composite film having a second adhesive layer with a thickness of 75 μm.

An adhesive film for wafer handling with a total thickness of 205 μm was prepared by bonding the composite film having the above first adhesive layer and the composite film having the second adhesive layer.

Embodiment 2 to embodiment 9 and comparative example 1 to comparative example 5

Adhesive films for wafer processing were prepared in the same manner as in Example 1. As shown in Tables 1 to 3 below, the types and thicknesses of the adhesive composition, the types and thicknesses of the upper substrate layer and the lower substrate layer were changed to prepare the respective adhesive films for wafer processing in Examples 2 to 9 and Comparative Examples 1 to 5.

Experimental example 1: Tensile elastic modulus of base layer and tensile strength of adhesive film for wafer processing

The tensile modulus of elasticity of the upper base material layer and the lower base material layer and the tensile strength of the wafer processing adhesive film in Examples 1 to 9 and Comparative Examples 1 to 5 were measured using a universal material testing machine (device name: 5566A_Instron) at a speed of 200 mm/min by preparing a test piece of 15 mm×200 mm in size, and are shown in Tables 1 to 3 below.

Experimental example 2: Shear storage modulus of the second bonding layer

The shear storage modulus of the second adhesive layer in Examples 1 to 9 and Comparative Examples 1 to 5 was prepared by laminating the adhesive compositions of Preparation Example 3 and Preparation Example 4 to form a circular test piece with a diameter of 8 mm and a thickness of 500 μm. The measurement temperature was set at 0 to 80° C., the heating rate was 10/min, and the measurement frequency was 0.796 Hz. The shear storage modulus measurement equipment (device name: ARES G2_TA Instruments) was used for measurement, and indicated In Tables 1 to 3 below.

Experimental Example 3: Creep

The first adhesive composition and the second adhesive composition of Example 1 to Example 9 and Comparative Example 1 to Comparative Example 5 were respectively prepared into samples, and the creep value was measured. The above samples were prepared by coating the adhesive composition used to form the adhesive layer of the measurement object on a polyethylene terephthalate (PET) adherend according to the thicknesses of the first adhesive layer and the second adhesive layer described in Tables 1 to 3 below, dried at 100°C for 4 minutes, and then aged for 3 days in a constant temperature and humidity device at a temperature of 40°C and a relative humidity of 50%. Afterwards, the prepared adhesive layer sample was cut into a size of 15mm×120mm, and adhered to the adherend for creep measurement with an adhesion area of 15mm×15mm. Using a universal physical property analyzer (equipment name: TA.XT Plus_Stable Micro Systems) at a temperature environment of 30°C and 60°C, when a force of 1.5kg was applied for 1000 seconds, the length (μm) of the adhesive layer deformed along the direction of the applied force was used as the creep value, and expressed In Tables 1 to 3 below.

Experimental Example 4: Back Grinding Process

On the semiconductor circuit surface of a wafer with a diameter of 8 inches and a thickness of 775 μm, use a dicing and dividing (sawing; sawing) device (device name: DFD6341_DISCO), use a blade with a width of 32.5 mm to perform half-cutting (pre-cutting) in a size of 5 mm × 5 mm, and stick (Device name: DT-ECS2030-SL_Dynatech) the wafer processing adhesives of Examples 1 to 9 and Comparative Examples 1 to 5 conjunctiva. Afterwards, the back grinding process (equipment name: DGP8760_DISCO) was performed until the thickness of the wafer reached 50 μm. After the backside grinding process, dicing tape is attached to the back of the wafer with the adhesive film for wafer processing attached, and 300mJ/cm2 of ultraviolet A is irradiated on the adhesive film for wafer processing, and then the adhesive film for wafer processing is removed to obtain diced wafer chips.

Experimental Example 5: Measuring the distance between chips (= cutout; kerf)

In the above-mentioned Experimental Example 4, when the point where four corners of arbitrary wafer chips are gathered on the diced wafer adhered to the dicing tape is taken as the measurement position P, the distance between adjacent chips among the four chips around P is referred to as L (the distance between four chips for each P is measured, L1 to L4). Select 12 arbitrary Ps (P1 to P12) for each wafer, and measure L1 to L48 (see Figure 3 for detailed measurement methods). In this case, the difference between the largest value and the smallest value among L1 to L48 is defined as a distance change between chips (=notch change). The incision changes of the wafer processing adhesive films of Examples 1 to 9 and Comparative Examples 1 to 5 were measured and shown in Tables 1 to 3 below.

Experimental Example 6: Crack Generation Rate Between Chips

In the above-mentioned Experimental Example 4, cracks were observed by microscopically observing the chips attached to the dicing tape. The crack generation rate means the percentage of cracked chips among all wafer chips that were diced, was defined and calculated by Equation 3 below, and is shown in Tables 1 to 3 below.

Formula 3: Crack generation rate (%) = (number of wafer chips with cracks/total number of wafer chips) × 100 (%)

Experimental Example 7: Curl Measurement

The wafer processing adhesive films of Examples 1 to 9 and Comparative Examples 1 to 5 were adhered on the semiconductor circuit surface of a wafer having a diameter of 8 inches and a thickness of 775 μm (device name: DT-ECS2030-SL_Dynatech). Afterwards, the back grinding process (equipment name: DGP8760_DISCO) was performed until the thickness of the wafer reached 50 μm.

After the back grinding process, the wafer with the adhesive film attached is placed on a horizontal platform at a temperature of 25°C and a relative humidity of 50%. The protruding part is in contact with the platform, and the height from the horizontal platform to the highest position is measured by a ruler, and its length is defined as curl. When the length of the curl was 10 mm or less, it was evaluated as good (◯), and when it exceeded 10 mm, it was evaluated as poor (×), which are shown in Tables 1 to 3 below.

Table 1 Example 1 Example 2 Example 3 Example 4 Example 5 Type and thickness of the first adhesive layer [μm] A1 30 30 60 A2 30 30 Type and thickness of the second adhesive layer [μm] B1 50 50 50 50 50 B2 Type and thickness of upper substrate layer [μm] PET (50) PET (50) PET (50) PET (50) PET (50) The type and thickness of the lower substrate layer [μm] PET (25) PET (50) PET (25) PET (50) PET (25) Tensile elastic modulus of upper substrate layer [MPa] 3000 3000 3000 3000 3000 Tensile elastic modulus of the lower substrate layer [MPa] 3000 3000 3000 3000 3000 Shear storage modulus of the second bonding layer [MPa] 30℃ 0.19 0.19 0.19 0.19 0.19 60℃ 0.1 0.1 0.1 0.1 0.1 Tensile strength [MPa] 79 98 78 97 79 Creep (μm, @30℃) C1 72 72 94 94 91 C2 81 81 81 81 81 Creep (μm, @60℃) C1' 98 98 153 153 131 C2' 115 115 115 115 115 Creep ratio C1/C2 0.89 0.89 1.16 1.16 1.12 C1'/C2' 0.85 0.85 1.33 1.33 1.14 Notch change (μm) 19.7 11.4 21.0 12.3 20.8 Crack rate (%) 0.8 0.6 1.5 1.0 1.4 curl ○ ○ ○ ○ ○

Table 2 Example 6 Example 7 Example 8 Example 9 Type and thickness of the first adhesive layer [μm] A1 60 30 30 30 A2 Type and thickness of the second adhesive layer [μm] B1 100 50 50 B2 50 Type and thickness of upper substrate layer [μm] PET (50) PET (50) PET (50) PET (50) The type and thickness of the lower substrate layer [μm] PET (25) PET (25) PI (25) PEN (25) Tensile elastic modulus of upper substrate layer [MPa] 3000 3000 3000 3000 Tensile elastic modulus of the lower substrate layer [MPa] 3000 3000 4300 5000 Shear storage modulus of the second bonding layer [MPa] 30℃ 0.08 0.19 0.19 0.19 60℃ 0.02 0.1 0.1 0.1 Tensile strength [MPa] 78 79 85 89 Creep (μm, @30℃) C1 91 72 72 72 C2 122 106 81 81 Creep (μm, @60℃) C1' 131 98 98 98 C2' 303 154 115 115 Creep ratio C1/C2 0.75 0.68 0.89 0.89 C1'/C2' 0.43 0.64 0.85 0.85 Notch change (μm) 12.8 19.2 16.7 15.4 Crack rate (%) 1.6 1.3 0.8 0.7 curl ○ ○ ○ ○

"PI" and "PEN" in Table 1 and Table 2 above mean polyimide and polyethylene naphthalate.

table 3 Comparative example 1 Comparative example 2 Comparative example 3 Comparative example 4 Comparative Example 5 Type and thickness of the first adhesive layer [μm] A1 30 30 30 30 A2 60 Type and thickness of the second adhesive layer [μm] B1 50 50 50 50 B2 120 Type and thickness of upper substrate layer [μm] PET (50) PET (50) PE (50) PET (50) PET (50) The type and thickness of the lower substrate layer [μm] EVA (25) PE (25) PET (25) PET (50) PET (25) Tensile elastic modulus of upper substrate layer [MPa] 3000 3000 350 3000 3000 Tensile elastic modulus of the lower substrate layer [MPa] 100 350 3000 3000 3000 Shear storage modulus of the second bonding layer [MPa] 30℃ 0.19 0.19 0.19 0.08 0.19 60℃ 0.1 0.1 0.1 0.02 0.1 Tensile strength [MPa] 49 53 50 95 79 Creep (μm, @30℃) C1 72 72 72 72 123 C2 81 81 81 216 81 Creep (μm, @60℃) C1' 98 98 98 98 275 C2' 115 115 115 681 115 Creep ratio C1/C2 0.89 0.89 0.89 0.33 1.52 C1'/C2' 0.85 0.85 0.85 0.14 2.39 Notch change (μm) 31.9 34.2 36.0 40.1 32.8 Crack rate (%) 3.4 4.1 4.9 6.7 4.8 curl x x x ○ ○

"EVA" and "PE" in Table 3 above mean ethylene vinyl acetate and polyethylene.

As described above, although the present invention has been described with reference to the illustrated drawings, the present invention is not limited by the embodiments and drawings disclosed in this specification, and it is obvious that those skilled in the art can implement various modifications within the scope of the technical idea of the present invention. Furthermore, even if the effect on the structure of the present invention is not explicitly described in the first description of the embodiment of the present invention, the effect that can be predicted by the corresponding structure should be recognized.

100: Adhesive film for wafer processing 110: multi-layer substrate 111: lower substrate layer 112: upper substrate layer 113: primer layer 115: Second bonding layer 120: the first bonding layer A1-A10: Bonding Compositions L1-L4: Distance between chips

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

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

3 is a schematic diagram for briefly explaining a method of measuring the distance between chips (=kerf width) in Experimental Example 5 of the present invention.

100: Adhesive film for wafer processing

110: Substrate

111: lower substrate layer

112: upper substrate layer

115: Second bonding layer

120: the first bonding layer

Claims (10)

An adhesive film for wafer processing, comprising: a multi-layer substrate comprising an upper substrate layer and a lower substrate layer; a first adhesive layer configured on the upper substrate layer; and The second adhesive layer is configured between the upper substrate layer and the lower substrate layer, The adhesive film for wafer processing satisfies the following formulas 1 and 2, and has a tensile strength of 70-150 MPa: Formula 1: 0.2≤C1/C2≤1.4, In the formula 1, C1 is the creep value of the first bonding layer under the temperature condition of 30°C, C2 is the creep value of the second bonding layer under the temperature condition of 30°C, and the unit of the creep value is μm Formula 2: 0.2≤C1'/C2'≤1.4, In the above formula 2, C1' is the creep value of the first adhesive layer under the temperature condition of 60°C, and C2' is the creep value of the second adhesive layer under the temperature condition of 60°C, and the unit of the creep value is μm. The adhesive film for wafer processing according to claim 1, wherein the C1 and C1' are respectively 30-200 μm. The adhesive film for wafer processing according to Claim 1, wherein the C2 and C2' are 50-350 μm, respectively. The adhesive film for wafer processing according to claim 1, wherein the sum of the thicknesses of the first adhesive layer and the second adhesive layer is 20-150 μm. The adhesive film for wafer processing as claimed in claim 1, wherein the lower base material layer and the upper base material layer respectively include at least one selected from the group consisting of polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate, wholly aromatic polyester, polyimide, polyamide, polycarbonate, polyacetal, modified polyphenylene ether, polyphenylene sulfide, polypyrene, polyether ketone, and biaxially oriented polypropylene. The adhesive film for wafer processing according to claim 5, wherein the lower base material layer and the upper base material layer are formed of polyethylene terephthalate material. The adhesive film for wafer processing according to claim 1, wherein the first adhesive layer is formed of an ultraviolet curable adhesive composition. The adhesive film for wafer processing according to claim 1, wherein the second adhesive layer is formed of a thermosetting adhesive composition. The adhesive film for wafer processing according to claim 1, wherein 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 further includes a primer layer. The adhesive film for wafer processing according to claim 1, wherein the shear storage modulus of the second adhesive layer under the temperature conditions of 30° C. and 60° C. is 0.02-1.0 MPa.

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