KR102292205B1 - Adhesive film for wafer processing - Google Patents

Abstract

Disclosed is an adhesive film for wafer processing, capable of obtaining an effect of preventing collision of semiconductor chips in a wafer processing process. The adhesive film for wafer processing according to the present invention includes: a multi-layer substrate; and a first adhesive layer disposed on the upper surface of the multi-layer substrate, wherein the multi-layer substrate has a sandwich structure in which a second adhesive layer is interposed between a lower substrate layer and an upper substrate layer.

Description

Adhesive film for wafer processing {ADHESIVE FILM FOR WAFER PROCESSING}

The present invention relates to an adhesive film for wafer processing used in wafer processing such as wafer backgrinding. More specifically, the present invention relates to an adhesive film for wafer processing that is excellent in preventing chip collision during wafer processing.

The present invention also relates to a wafer-adhesive film assembly in which an adhesive film is adhered to the wafer.

With the recent development of technology, miniaturization and thinning of semiconductor chips are required.

A representative method for reducing the thickness of the chip is to reduce the thickness by grinding the back surface of the wafer on which the chip is formed.

Recently, in order to obtain a thin chip, a DBG (Dicing Before Grinding) method is used, which forms a groove from the surface of the wafer using a dicing blade, and then performs grinding from the back surface of the wafer to obtain individualized chips from the wafer. have. In the case of the DBG method, since the back surface grinding of the wafer and the separation of the wafer are performed simultaneously, a thin semiconductor chip can be efficiently manufactured.

In order to maintain the semiconductor chip during the backside grinding of the wafer, it is common to perform the backside grinding of the wafer in a state in which an adhesive film is attached to the surface of the wafer. Such an adhesive film includes an adhesive layer for adhesion to the substrate and the wafer surface, and a buffer layer or a shock absorbing layer such as urethane acrylate is formed on the back surface of the substrate for a buffering effect.

In the case of a buffer layer or a shock-absorbing layer such as urethane acrylate, it is formed through energy ray curing. In this energy ray curing method, since polymers having a functional group having a double bond are formed as one macromolecule, there is a disadvantage in that the modulus is increased and the buffer effect is reduced.

The problem to be solved by the present invention is to provide an adhesive film for wafer processing excellent in chip collision prevention effect.

Another object of the present invention is to provide a wafer-adhesive film assembly suitable for wafer processing such as a backgrinding process.

The technical problem to be achieved by the present invention is not limited to the above-mentioned problems, and other problems not mentioned will be clearly understood by those skilled in the art from the following description.

A pressure-sensitive adhesive film for wafer processing according to an embodiment of the present invention for solving the above problems is a multi-layer substrate; and a first pressure-sensitive adhesive layer disposed on the upper surface of the multilayer substrate. The multilayer substrate has a sandwich structure in which a second pressure-sensitive adhesive layer is interposed between the upper substrate layer and the lower substrate layer, the lower substrate layer and the upper substrate layer have a modulus of 1,000 MPa or more, and the second adhesive layer has a modulus of 10 MPa or less. has a modulus.

The lower base layer and the upper base layer are each polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate, wholly aromatic polyester, polyimide, polyamide, polycarbonate, polyacetal, modified polyphenylene oxide, polyphenylene sulfide. It may include at least one of phide, polysulfone, polyetherketone, and biaxially oriented polypropylene.

The lower substrate layer and the upper substrate layer may be made of polyethylene terephthalate (PET).

The second pressure-sensitive adhesive layer may have a glass transition temperature of 10° C. or less.

The second pressure-sensitive adhesive layer may include a thermosetting acrylic pressure-sensitive adhesive.

The second pressure-sensitive adhesive layer may have a thickness of 100 μm or less.

A primer layer may be additionally 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.

In the wafer-adhesive film assembly according to an embodiment of the present invention for solving the above problems, the adhesive film as described above is adhered to the surface of the wafer on which a plurality of semiconductor chips are formed.

The adhesive film for wafer processing according to the present invention includes a multilayer substrate having a sandwich structure in which a second adhesive layer having a low modulus of 10 MPa or less is interposed between substrate layers having a high modulus of 1,000 MPa or more. Substrate layers having a high modulus of 1,000 MPa or more provide sufficient modulus to support a wafer in a wafer processing process such as a wafer backgrinding process. In addition, the second pressure-sensitive adhesive layer with a low modulus can better absorb the impact transmitted by the substrate layers having a high modulus during wafer processing such as wafer backgrinding, thereby preventing collision of the semiconductor chip and generating cracks. can be suppressed.

In addition, when the second pressure-sensitive adhesive layer has a low modulus of 10 MPa or less and a low glass transition temperature of 10° C. or less, a higher impact absorption effect may be provided.

In addition, when the second adhesive layer has a low modulus of 10 MPa or less and a thickness of 100 μm or less, deformation of the adhesive film or separation of the second adhesive layer during wafer processing such as wafer backgrinding can be prevented. .

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.

The objects, specific advantages and novel features of the present invention will become more apparent from the following detailed description taken in conjunction with the accompanying drawings and preferred embodiments. 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 component is not limited by the terms. Hereinafter, in describing the present invention, detailed descriptions of related known technologies that may unnecessarily obscure the gist of the present invention will be omitted.

Hereinafter, the adhesive film for wafer processing according to the present invention will be described in detail with reference to the drawings.

In the present invention, wafer processing may include a wafer backgrinding process, a dicing process, a pick-up process of individualized semiconductor chips, and the like.

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 according to the present invention includes a multilayer substrate 110 and a first adhesive layer 120 disposed on the upper surface of the multilayer substrate.

multi-layered substrate

The multilayer substrate 110 includes a lower substrate layer 111 , an upper substrate layer 112 , and a second adhesive layer 115 . The second pressure-sensitive adhesive layer 115 is disposed between the lower substrate layer 111 and the upper substrate layer 112 . In the adhesive film for wafer processing according to 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 modulus. More specifically, the lower substrate layer 111 and the upper substrate layer 112 may have a modulus of 1,000 MPa or more, for example, 1,200 MPa or more, 1,500 MPa or more, 2,000 MPa or more, 3,000 MPa or more. Modulus is based on 23°C measurements. What is peculiar in the present invention is that not only the upper substrate layer 112 on the side to which the wafer is adhered, but also the lower substrate layer 111 is formed of a material having a high modulus.

When the modulus of the upper substrate layer 112 and the lower substrate layer 111 is relatively low (less than 1,000 MPa), the support force of the wafer or the fragmented semiconductor chip is low, and there is a possibility that the semiconductor chip collides in the backgrinding process. However, in the case of the present invention, by the lower base layer 111 and the upper base layer 112 having a high modulus, it is possible to sufficiently increase the supporting force of the wafer or the individualized semiconductor chip, and in a wafer processing process such as wafer backgrinding. It is possible to provide an effect of preventing collision of semiconductor chips.

In addition, when the modulus of the lower substrate layer 111 and the upper substrate layer 112 is high, the stress applied to the wafer or semiconductor chip when the wafer is adhered to the adhesive film or when the wafer or semiconductor chip is peeled from the wafer adhesive film. can be made small

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

Preferably, the lower substrate layer 111 and the upper substrate layer 112 may be made of the same material. For example, the lower substrate layer 111 and the upper substrate layer 112 may be made of polyethylene terephthalate (PET). PET may have a modulus of 1,000 MPa or more, so it is suitable for use as the lower substrate layer 111 and the upper substrate layer 112 .

The modulus of the lower substrate layer 111 and the upper substrate layer 112 may be adjusted. For example, the modulus of the substrate layer may be increased by reducing the content of the ethylene component in the copolymerization component in PET synthesis.

The lower substrate layer 111 and the upper substrate layer 112 may have the same thickness, but is not limited thereto. The lower base layer 111 and the upper base layer 112 may each have a thickness of about 10 to 150 μm. On the other hand, in the present invention, since the lower substrate layer 111 and the upper substrate layer 112 have a high modulus, the thickness of the lower substrate layer 111 and the upper substrate layer 112, particularly the upper substrate layer 112, is too high. If it is thick, it may be vulnerable to impacts generated during wafer processing such as backgrinding. Accordingly, the thickness of the lower substrate layer 111 and the upper substrate layer 112 is preferably set to about 150 μm or less.

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 111 and/or the upper substrate layer 112 .

2nd adhesive layer

In the present invention, the second pressure-sensitive adhesive layer 115 has a modulus of 10 MPa or less. The second pressure-sensitive adhesive layer 115 that satisfies this may be formed of, for example, a thermosetting acrylic pressure-sensitive adhesive. The thermosetting acrylic pressure-sensitive adhesive may be prepared by thermosetting a composition including a resin and a heat curing agent.

A conventional energy ray polymerizable urethane acrylate impact absorbing layer has a high modulus by forming the entire layer of one macropolymer by energy ray curing, and this high modulus may act as an obstacle to shock absorption. On the other hand, the second pressure-sensitive adhesive layer 115 applied to the present invention may be formed of a thermosetting acrylic pressure-sensitive adhesive and have a low modulus of 10 MPa or less, thereby exhibiting superior impact absorption ability. Meanwhile, the modulus or the glass transition temperature of the second pressure-sensitive adhesive layer 115 may vary depending on the composition of the resin, the content of the curing agent, and the like.

In the thermosetting acrylic pressure-sensitive adhesive, the resin may be, for example, an acrylate compound. As the acrylate compound usable for the thermosetting acrylic pressure-sensitive adhesive, (meth)acrylate, an alkyl (meth)acrylate such as an alkyl (meth)acrylate having 4 or more carbon atoms, a non-urethane-based polyfunctional (meth)acrylate, etc. may be presented. have.

The curing agent usable for the thermosetting acrylic pressure-sensitive adhesive may include an isocyanate-based crosslinking agent, a carbodiimide-based crosslinking agent, an oxazoline-based crosslinking agent, an epoxy-based crosslinking agent, an aziridine-based crosslinking agent, a peroxide, and the like. The content of the curing agent may be 0.1 to 2 parts by weight based on 100 parts by weight of the resin, but is not necessarily limited thereto.

In the case of the present invention, the lower substrate layer 111 and the upper substrate layer 112 have a high modulus of 1,000 MPa or more, but the second adhesive layer 115 between these substrate layers is sufficient by exhibiting a low modulus of 10 MPa or less. It can exhibit shock absorption function. For example, the semiconductor chips may vibrate or move due to compression and shear stress generated in the wafer backgrinding process, and thus the semiconductor chips may collide with each other. However, in the present invention, since shock absorption is possible through the second pressure-sensitive adhesive layer 115 having a low modulus between the lower substrate layer 111 and the upper substrate layer 112 having a high modulus, such a collision of semiconductor chips is prevented. can do.

As described above, the second pressure-sensitive adhesive layer 115 may have a modulus of 10 MPa or less, preferably 0.01 MPa or more and 5 MPa or less, and more preferably 0.05 MPa or more and 5 MPa or less. When the modulus of the second pressure-sensitive adhesive layer exceeds 10 Mpa, since the impact mitigating effect is insufficient, the impact at the time of grinding transmitted through the substrate having a high modulus cannot be buffered, so that cracks may occur in the wafer, and it will be difficult to prevent chip collision. can On the other hand, when the modulus of the second pressure-sensitive adhesive layer is less than 0.01 MPa, the degree of curing of the pressure-sensitive adhesive is too low, and the pressure-sensitive adhesive flows due to heat and pressure during wafer backgrinding, thereby contaminating the wafer or the thickness precision of the wafer may be deteriorated after processing.

Meanwhile, the second pressure-sensitive adhesive layer 115 may have a thickness of 100 μm or less. When the thickness of the second pressure-sensitive adhesive layer exceeds 100 μm, for example, the second pressure-sensitive adhesive layer having a low modulus is deformed by the stress applied to the pressure-sensitive adhesive film during wafer backgrinding, so that the chip held on the pressure-sensitive adhesive film is displaced or the wafer The second pressure-sensitive adhesive layer may be separated by impact during processing. That is, thickness uniformity may deteriorate after grinding. Therefore, the thickness of the second pressure-sensitive adhesive layer is preferably 100 μm or less, and more preferably, may be set to about 5 to 70 μm.

In addition, the second pressure-sensitive adhesive layer 115 may have a glass transition temperature (Tg) of 10° C. or less, preferably, a glass transition temperature of -40 to 10° C., more preferably -35 It may have a glass transition temperature between ~ 10 ℃, most preferably may have a glass transition temperature between -30 ~ 8 ℃. Due to the low glass transition temperature of the second adhesive layer, strong adhesive force can be obtained, and as a result, the separation of the first substrate and the second substrate can be prevented even when wafer backgrinding is performed at a maximum of 90° C. from room temperature during grinding. have. However, if it has an excessively low glass transition temperature of less than -40°C, an adhesive may flow and contaminate the wafer due to heat and pressure during wafer backgrinding.

first adhesive layer

In FIG. 1 , the first pressure-sensitive adhesive layer 120 is a portion that is adhered to the wafer.

The first pressure-sensitive adhesive layer 120 is not particularly limited as long as it has adequate adhesiveness at room temperature, and various pressure-sensitive adhesives such as known UV adhesives may be applied.

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

2 is a cross-sectional view schematically showing an adhesive film for wafer processing according to 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 multilayer substrate. The primer layer 113 may be for improving adhesion between the first pressure-sensitive adhesive layer 120 and the multilayer substrate 110 .

The primer layer 113 may be formed as a separate layer on the upper surface of the upper base layer 112 , that is, on the surface on which the first pressure-sensitive 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. A primer layer may also be formed on the surface.

The processing of the wafer may be performed while the adhesive film according to the present invention is attached to the surface of the wafer.

An example of a wafer backgrinding process is as follows. First, a groove or a modified region is formed on a wafer to which the adhesive film according to the present invention is adhered by using laser dicing, plasma dicing, or the like. This can be done from the wafer surface or from the back side. Thereafter, wafer backgrinding is performed through a grinding process, and the adhesive film is peeled off after being divided into a plurality of chips through a groove or a modified region.

<Example>

Hereinafter, preferred examples are presented to help the understanding of the present invention. However, the following examples are only provided for easier understanding of the present invention, and the contents of the present invention are not limited by the following examples.

1. Preparation of adhesive resin for the second adhesive layer

120 parts of ethyl acetate was put into a reaction vessel equipped with a cooling tube, a nitrogen introduction tube, a thermometer, and a stirrer, the air in the apparatus was substituted with nitrogen gas to prevent oxygen from being contained, and then the internal temperature of the vessel was raised to 75°C. After adding the entire amount of a solution of 0.05 parts of azobisisobutyronitrile (polymerization initiator) dissolved in 5 parts of ethyl acetate, while maintaining the internal temperature at 74 to 76° C., a monomer mixture having the composition shown in Table 1 was reacted over 2 hours. loaded within. Further, the reaction was completed by keeping the temperature at an internal temperature of 74 to 76°C for 5 hours. Finally, ethyl acetate was added to adjust the concentration of the (meth)acrylic resin to 40% to prepare a resin.

The weight average molecular weight (Mw), number average molecular weight (Mn) and glass transition temperature (Tg) of the prepared resin were measured. The molecular weights (Mw and Mn) of the prepared resin were measured as follows. Columns are arranged in series in a GPC device (model name: AGILENT-1200), and tetrahydrofuran is used as an eluent, sample concentration 5 mg/mL, sample introduction amount 100 μL, temperature 40° C., flow rate 1 mL/min. was measured in terms of standard polystyrene.

The glass transition temperature (Tg) of the prepared resin was measured using a dynamic mechanical analyzer Q-800 equipment from TA Instruments, under the condition of a measurement temperature range of -80 to 50° C. and a temperature increase rate of 10° C./min. The monomer composition (% by weight) of the monomer mixture used to prepare the second pressure-sensitive adhesive, and the weight average molecular weight (Mw), molecular weight distribution Mw/Mn, and glass transition temperature (Tg) of the prepared resin are summarized in Table 1.

[Table 1]

BA: n-butyl acrylate

EHA :2-ethyl hexyl acrylate

MA: methyl acrylate

HEA: 2-hydroxylethyl acrylate

AA: acrylic acid

2. Preparation of adhesive film

Between the upper substrate and the lower substrate shown in Table 3, the pressure-sensitive adhesive composition having the composition shown in Table 2 was applied and heat-cured to form a second pressure-sensitive adhesive layer.

[Table 2]

In Table 2, U-CAT 5003 (manufactured by San Apro) was used as the curing agent, KBM-403 (manufactured by Shinyetsu) was used as the additive as an epoxy silane coupling agent, and SFP-30M (average particle diameter of 0.7 μm) as the filler as silica. (manufactured by Electrochemical Industry Co., Ltd.) was used.

Then, on top of the upper substrate, by forming a first pressure-sensitive adhesive layer with the same UV pressure-sensitive adhesive film samples were prepared.

2. Evaluation of the backgrinding properties of the adhesive film

After attaching a wafer including 320 semiconductor chips to the prepared adhesive films, grinding was performed under the same conditions, and the wafer thickness uniformity after grinding, sludge intrusion evaluation, and chip corner crack characteristics were evaluated.

In Table 3, the thickness uniformity and the presence or absence of sludge intrusion after grinding were evaluated under the following conditions.

A: Wafer thickness deviation 10㎛ or less after grinding

B: After grinding, the thickness deviation of the wafer exceeds 10 μm

C: No sludge intrusion

D: Sludge intrusion

[Table 3]

Referring to Table 3, in the case of the specimens according to Examples 1 to 5, wherein the modulus of the upper substrate and the lower substrate is 1000 MPa or more, and the modulus of the second adhesive layer is 10 MPa or less, relatively few chip corner cracks were exhibited. In contrast, the specimens according to Comparative Examples 1 and 2, in which the modulus of the substrate is less than 1000 MPa, and the specimen according to Comparative Example 3, in which the modulus of the second adhesive layer exceeds 10 MPa, exhibited relatively high chip corner cracks.

In addition, among the specimens according to Examples 1 to 5, the specimens according to Examples 1 to 3 exhibited better characteristics in the evaluation of thickness uniformity after grinding. That is, the specimens according to Examples 1 to 3 have a thickness uniformity after grinding compared to the specimens according to Example 4 in which the modulus of the second adhesive layer is only 0.005 MPa and the specimen according to Example 5 in which the thickness of the second adhesive layer exceeds 100 μm. The evaluation showed better properties.

As described above, the adhesive film for wafer processing according to the present invention includes a multilayer substrate having a sandwich structure in which a second adhesive layer having a low modulus is interposed between substrate layers having a high modulus. While providing a sufficient modulus to obtain a chip collision prevention effect in a wafer processing process such as a wafer backgrinding process by the substrate layers having a high modulus, a sufficient buffering effect can be provided by the second pressure-sensitive adhesive layer having a low modulus. .

Although the present invention has been described as described above, the present invention is not limited by the embodiments disclosed herein, and it is apparent that various modifications may be made by those skilled in the art within the scope of the technical idea of the present invention. In addition, although the effects of the configuration of the present invention are not explicitly described and described while describing the embodiments of the present invention, it is natural that the effects predictable by the configuration should also be recognized.

110: description
111: lower base layer
112: upper substrate layer
113: primer layer
115: second pressure-sensitive adhesive layer
120: first pressure-sensitive adhesive layer

Claims (8)

multilayer substrates; and
A first pressure-sensitive adhesive layer disposed on the upper surface of the multi-layer substrate,
The multilayer substrate has a sandwich structure in which a second pressure-sensitive adhesive layer is interposed between the upper substrate layer and the lower substrate layer,
The lower substrate layer and the upper substrate layer have a modulus of 1,000 MPa or more,
The second pressure-sensitive adhesive layer has a modulus of 10 MPa or less, and a glass transition temperature of -35 ℃ ~ 10 ℃ pressure-sensitive adhesive film for processing.
According to claim 1,
The lower base layer and the upper base layer are each polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate, wholly aromatic polyester, polyimide, polyamide, polycarbonate, polyacetal, modified polyphenylene oxide, polyphenylene sulfide. An adhesive film for wafer processing, comprising at least one selected from the group consisting of phide, polysulfone, polyether ketone, and biaxially stretched polypropylene.
3. The method of claim 2,
The adhesive film for wafer processing, characterized in that the lower substrate layer and the upper substrate layer are made of a polyethylene terephthalate material.
According to claim 1,
The second pressure-sensitive adhesive layer is an adhesive film for wafer processing, characterized in that it comprises a thermosetting acrylic pressure-sensitive adhesive.
According to claim 1,
The second pressure-sensitive adhesive layer is an adhesive film for wafer processing, characterized in that it has a thickness of 100 μm or less.
According to claim 1,
At least one surface 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, the adhesive film for wafer processing, characterized in that it further comprises a primer layer.
A wafer-adhesive film assembly, characterized in that the adhesive film according to any one of claims 1 to 6 is adhered to the surface of the wafer on which a plurality of semiconductor chips are formed. delete

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