阅读说明：本技术 背面研磨带 (Back grinding belt ) 是由 尹美善 金色拉 李光珠 延博拉 朴成灿 金殷英 于 2019-01-11 设计创作，主要内容包括：本发明涉及背面研磨带和使用该背面研磨带研磨晶片的方法,所述背面研磨带包括聚合物基底和粘合层,其中所述粘合层包含含有30重量％至60重量％的衍生自玻璃化转变温度为0℃或更高的单体或低聚物的重复单元的(甲基)丙烯酸酯树脂,以及其中所述粘合层的玻璃化转变温度为-20℃至10℃。(The present invention relates to a back-grinding tape comprising a polymer substrate and an adhesive layer, wherein the adhesive layer comprises a (meth) acrylate resin containing 30 to 60% by weight of a repeating unit derived from a monomer or oligomer having a glass transition temperature of 0 ℃ or more, and wherein the adhesive layer has a glass transition temperature of-20 to 10 ℃, and a method of grinding a wafer using the back-grinding tape.)

1. A back side grinding belt comprises a polymer substrate and a bonding layer,

wherein the adhesive layer comprises a (meth) acrylate resin containing 30 to 60% by weight of a repeating unit derived from a monomer or oligomer having a glass transition temperature of 0 ℃ or more, and

wherein the glass transition temperature of the bonding layer is from-20 ℃ to 10 ℃.

2. The backgrinding tape of claim 1, wherein

The monomer or oligomer having a glass transition temperature of 0 ℃ or more includes at least one compound selected from the group consisting of methyl acrylate, isobornyl (meth) acrylate, and hydroxycyclohexyl (meth) acrylate.

3. The backgrinding tape of claim 1, wherein

The (meth) acrylate resin further comprises a (meth) acrylate-based repeating unit having an alkyl group having 2 to 12 carbon atoms or a (meth) acrylate-based repeating unit containing a crosslinkable functional group, together with a repeating unit derived from the monomer or oligomer having a glass transition temperature of 0 ℃ or more.

4. The backgrinding tape of claim 3, wherein

The (meth) acrylate resin comprises 30 to 60% by weight of repeating units derived from a monomer or oligomer having a glass transition temperature of 0 ℃ or higher, and

40 to 70% by weight of a (meth) acrylate-based repeating unit having an alkyl group having 2 to 12 carbon atoms or a (meth) acrylate-based repeating unit containing a crosslinkable functional group.

5. The backgrinding tape of claim 1, wherein

When a force of 20000Pa is applied to the adhesive layer at 90 ℃, the creep deformation is 10% to 30%.

6. The backgrinding tape of claim 1, wherein

The adhesive layer further comprises a multifunctional (meth) acrylate compound.

7. The backgrinding tape of claim 6, wherein

The multifunctional (meth) acrylate compound has a weight average molecular weight of 100 to 100000, and includes at least one selected from the group consisting of a multifunctional urethane (meth) acrylate and a multifunctional (meth) acrylate monomer or oligomer.

8. The backgrinding tape of claim 1, wherein

The adhesive layer contains a photo-initiator,

at least one crosslinking agent selected from the group consisting of: isocyanate-based compounds, aziridine-based compounds, epoxy-based compounds, and metal chelate-based compounds,

or

At least one tackifier selected from the group consisting of: rosin resins, terpene resins, phenol resins, styrene resins, aliphatic petroleum resins, aromatic petroleum resins, and aliphatic and aromatic copolymerized petroleum resins.

9. The backgrinding tape of claim 1, wherein

The polymeric substrate comprises at least one polymeric resin selected from the group consisting of: low density polyethylene, linear polyethylene, medium density polyethylene, high density polyethylene, ultra-low density polyethylene, random copolymers of polypropylene, block copolymers of polypropylene, homopolypropylene, polymethylpentene, ethylene-vinyl acetate copolymers, ethylene-methacrylic acid copolymers, ethylene-methyl methacrylate copolymers, ethylene-ionomer copolymers, ethylene-vinyl alcohol copolymers, polybutylene, and styrene copolymers.

10. A method of grinding a wafer using the back side grinding tape of claim 1.

Technical Field

Cross Reference to Related Applications

This application claims the benefit of the application date of korean patent application No. 10-2018-.

The present invention relates to a back-grinding tape.

Background

Recently, the trend of electronic devices toward miniaturization, high functionality, and capacity increase is increasing, and the demand for densification and high integration of semiconductor packages is rapidly increasing. Reflecting this, the size of the semiconductor chip becomes larger, and at the same time, the thickness of the chip becomes thinner, and the integration degree of the circuit increases. However, the modulus of the chip itself is lowered, thereby causing a problem in terms of the reliability of the manufacturing process or the final product.

In order to meet such demands for enlargement and thinning of semiconductors, a grinding (back grinding) process for facilitating assembly is basically performed to reduce the thickness of a chip by grinding the back surface of a wafer with a polishing wheel composed of fine diamond particles. However, during the grinding process, damage to the wafer, such as contamination or cracking, often occurs due to large amounts of silicon residues (dust) and particles. Therefore, the role of an adhesive film or a back grinding tape for protecting the surface of a semiconductor wafer is further emphasized.

As semiconductor devices are further miniaturized and thinned, a process of grinding a wafer to a thinner thickness than a conventional wafer is required. Therefore, when the adhesive film used in the step of grinding the wafer to a thickness of about 100 μm is applied to the process of grinding the wafer to a thickness of about 50 μm, creep deformation of the adhesive tape is high, which may cause problems such as die misalignment (misalignment of die) after grinding.

Disclosure of Invention

Technical problem

An object of the present invention is to provide a back grinding tape which can be easily applied to a process of grinding a wafer having a thin thickness, and can prevent problems such as misalignment of a mold after grinding by keeping creep deformation of an adhesive tape at a low level.

Another object of the present invention is to provide a method of grinding a wafer using a back-grinding tape.

Technical scheme

In order to achieve the above object, the present invention provides a back-grinding tape comprising: a polymeric substrate; and an adhesive layer, wherein the adhesive layer comprises a (meth) acrylate resin containing 30 to 60 wt% of a repeating unit derived from a monomer or oligomer having a glass transition temperature of 0 ℃ or more, wherein the glass transition temperature of the adhesive layer is-20 to 10 ℃.

The invention also provides a method for grinding a wafer by using the back grinding belt.

Hereinafter, a back-grinding tape and a method of grinding a wafer according to embodiments of the present invention will be described in more detail.

As used herein, the term "(meth) acrylate" is intended to encompass both acrylates and methacrylates.

As described above, according to an embodiment of the present invention, there may be provided a back grinding tape including a polymer substrate and a bonding layer, wherein the bonding layer includes a (meth) acrylate resin containing 30 to 60% by weight of a repeating unit derived from a monomer or oligomer having a glass transition temperature of 0 ℃ or more, wherein the glass transition temperature of the bonding layer is-20 to 10 ℃.

The present inventors have studied on a back grinding tape comprising a polymer substrate and an adhesive layer, and found through experiments that, when the adhesive layer comprises a (meth) acrylate resin containing 30 to 60 wt% of repeating units derived from a monomer or oligomer having a glass transition temperature of 0 ℃ or more, the glass transition temperature thereof is-20 to 10 ℃, it can be easily applied to a process of grinding a wafer having a thin thickness of about 50 μm, and a problem such as mold misalignment after grinding can be prevented by keeping creep deformation of the adhesive tape at a low level, thereby completing the present invention.

More specifically, since the glass transition temperature of the adhesive layer is-20 ℃ to 10 ℃, the creep strain may be 10% to 30% when a force of 20000Pa is applied at 90 ℃. The condition of applying a force of 20000Pa at 90 ℃ may correspond to a horizontal force received by the grinding wheel during back grinding in the back grinding process. Since the creep deformation of the adhesive layer under the above conditions is 10% to 30%, the mold misalignment after the back grinding process can be prevented.

If creep deformation is less than 10% when a force of 20000Pa is applied to the adhesive layer at 90 ℃, the modulus of the adhesive layer is high and thus the adhesive stability is reduced, so that it may be released during the process. If the creep deformation is more than 30% when a force of 20000Pa is applied to the adhesive layer at 90 ℃, the modulus of the adhesive layer is low, and thus the mold may be misaligned or adhesive residues may be formed on the surface of the semiconductor circuit.

Creep deformation means deformation of a material with time when a certain force is applied to a predetermined material for a long time, and the degree of deformation tends to increase with the lapse of time.

The back-grinding tape of the present embodiment can exhibit a low level of creep deformation rate by including the aforementioned adhesive layer. Therefore, even when a force is applied to the semiconductor wafer to which the back-grinding tape is attached in the back-grinding process, the deformation of the adhesive layer may not be large, and the occurrence of mold shift due to the force applied to the wafer during the back-grinding process may be suppressed.

Since the adhesive layer includes a (meth) acrylate resin containing 30 to 60% by weight of a repeating unit derived from a monomer or oligomer having a glass transition temperature of 0 ℃ or more, the glass transition temperature thereof may be-20 to 10 ℃.

More specifically, the glass transition temperature of the monomer or oligomer having a glass transition temperature of 0 ℃ or more may be 0 ℃ to 100 ℃. Specific examples of the monomer or oligomer having a glass transition temperature of 0 ℃ or more include at least one compound selected from the group consisting of methyl acrylate, isobornyl (meth) acrylate, and hydroxycyclohexyl (meth) acrylate.

In addition, the (meth) acrylate resin may further include a (meth) acrylate-based repeating unit having an alkyl group having 2 to 12 carbon atoms or a (meth) acrylate-based repeating unit containing a crosslinkable functional group, together with a repeating unit derived from a monomer or oligomer having a glass transition temperature of 0 ℃ or more.

Specifically, the (meth) acrylate resin may include 30 to 60% by weight of a repeating unit derived from a monomer or oligomer having a glass transition temperature of 0 ℃ or more, and 40 to 70% by weight of a (meth) acrylate-based repeating unit having an alkyl group having 2 to 12 carbon atoms or a (meth) acrylate-based repeating unit containing a crosslinkable functional group.

The (meth) acrylate-based repeating unit having an alkyl group having 2 to 12 carbon atoms may be a repeating unit derived from at least one monomer or oligomer selected from the group consisting of: pentyl (meth) acrylate, n-butyl (meth) acrylate, ethyl (meth) acrylate, hexyl (meth) acrylate, n-octyl (meth) acrylate, isooctyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, dodecyl (meth) acrylate, decyl (meth) acrylate, and the like.

Specific examples of the (meth) acrylate-based repeating unit containing a crosslinkable functional group include a (meth) acrylate-based repeating unit containing a hydroxyl group, a carboxyl group, a nitrogen-containing functional group, and the like, and the (meth) acrylate-based repeating unit containing a crosslinkable functional group may be derived from a (meth) acrylate-based monomer containing a crosslinkable functional group.

In this case, examples of the hydroxyl group-containing (meth) acrylate-based monomer may include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, and the like. Examples of the carboxyl group-containing (meth) acrylate-based monomer may include (meth) acrylic acid and the like. Examples of the (meth) acrylate monomer having a nitrogen-containing functional group include, but are not limited to, (meth) acrylonitrile, N-vinylpyrrolidone, N-vinylcaprolactam, and the like.

The weight average molecular weight of the (meth) acrylate resin may be 100000 to 1500000, preferably 200000 to 1000000. When the weight average molecular weight of the (meth) acrylate resin is less than 100000, the coating property or cohesion is reduced, and a residue may remain on the adherend during peeling, or a fracture phenomenon of the adhesive may occur. In addition, when the weight average molecular weight of the (meth) acrylate resin is greater than 1500000, an additional dilution solvent needs to be added due to high viscosity, and coating characteristics may be deteriorated.

Meanwhile, the adhesive layer may include an ultraviolet curable adhesive or a heat curable adhesive. When the ultraviolet curable adhesive is used, ultraviolet rays are irradiated to increase the cohesive force and the glass transition temperature of the adhesive, thereby decreasing the adhesive strength. In the case of heat curable adhesives, the temperature is increased to reduce the bond strength.

The (meth) acrylate-based resin may further include a low molecular weight compound containing a carbon-carbon double bond of vinyl acetate, styrene, or acrylonitrile.

The adhesive layer may further include a multifunctional (meth) acrylate compound.

The multifunctional (meth) acrylate compound has a weight average molecular weight of 100 to 100000, and may include at least one selected from the group consisting of a multifunctional urethane (meth) acrylate and a multifunctional (meth) acrylate monomer or oligomer.

The weight average molecular weight is a weight average molecular weight in terms of polystyrene measured by a GPC method.

The content of the polyfunctional (meth) acrylate compound may be 5 parts by weight to 400 parts by weight, preferably 10 parts by weight to 200 parts by weight, based on 100 parts by weight of the (meth) acrylate resin. When the content of the polyfunctional (meth) acrylate compound is less than 5 parts by weight, the adhesive strength after curing may not be sufficiently reduced. When the content of the polyfunctional (meth) acrylate compound exceeds 400 parts by weight, the cohesive force of the adhesive before ultraviolet irradiation may be insufficient.

The adhesive layer may further comprise a photoinitiator. The type of the photoinitiator is not particularly limited, and a conventional initiator known in the art may be used. The content thereof may be 0.05 parts by weight to 20 parts by weight based on 100 parts by weight of the multifunctional (meth) acrylate compound. When the content of the photoinitiator is less than 0.05 parts by weight, the curing reaction by ultraviolet irradiation may be insufficient. When the content of the photoinitiator exceeds 20 parts by weight, a crosslinking reaction occurs in a short unit or an unreacted ultraviolet curable compound is generated during curing, which may cause residue on the surface of an adherend, or the peel force after curing may be too low.

The adhesive layer may comprise at least one crosslinker selected from the group consisting of: isocyanate-based compounds, aziridine-based compounds, epoxy-based compounds, and metal chelate-based compounds.

The crosslinking agent may be included in an amount of 2 to 40 parts by weight, preferably 2 to 20 parts by weight, based on 100 parts by weight of the multifunctional (meth) acrylate compound. When the content of the crosslinking agent is less than 2 parts by weight, the cohesive force of the adhesive may be insufficient, and when the content exceeds 20 parts by weight, the adhesion before ultraviolet irradiation may be insufficient.

The adhesive layer may further comprise at least one tackifier selected from the group consisting of: rosin resins, terpene resins, phenol resins, styrene resins, aliphatic petroleum resins, aromatic petroleum resins, and aliphatic and aromatic copolymerized petroleum resins.

The method of coating and drying the adhesive composition for forming the adhesive layer is not particularly limited, and for example, the following methods may be used: wherein a composition comprising the above-mentioned respective components is used as it is or diluted with an appropriate organic solvent, coated by a known tool such as comma coater, gravure coater, die coater or reverse coater, and then the solvent is dried at a temperature of 60 ℃ to 200 ℃ for 10 seconds to 30 minutes. Further, in the above process, an aging step may be additionally performed to perform a sufficient crosslinking reaction of the adhesive.

The thickness of the adhesive layer is not particularly limited, but may be, for example, in the range of 5 μm to 300 μm, or 10 μm to 100 μm.

On the other hand, the polymer substrate is not particularly limited, and examples of the polymer substrate include at least one polymer resin selected from the group consisting of: polyurethane, polyethylene terephthalate, low density polyethylene, linear polyethylene, medium density polyethylene, high density polyethylene, ultra-low density polyethylene, random copolymers of polypropylene, block copolymers of polypropylene, homopolypropylene, polymethylpentene, ethylene-vinyl acetate copolymers, ethylene-methacrylic acid copolymers, ethylene-methyl methacrylate copolymers, ethylene-ionomer copolymers, ethylene-vinyl alcohol copolymers, polybutylene, and styrene copolymers.

The thickness of the polymer substrate is not particularly limited, and may be, for example, in the range of 10 μm to 500 μm.

On the other hand, according to another embodiment of the present invention, there can be provided a method of grinding a wafer using the aforementioned back-grinding tape.

The step of grinding the semiconductor wafer may be performed in a state where a back-grinding tape is adhered to one surface of the semiconductor wafer. After the grinding step, the back-side grinding tape may be irradiated with ultraviolet rays or subjected to heat treatment or the like to peel the tape.

In the step of grinding the semiconductor wafer, a method of using a back grinding tape is not particularly limited, and for example, after attaching the back grinding tape to a half-cut circuit (half-cut circuit) surface at room temperature to a thickness of 50 μm, the back grinding tape may be attached to a semiconductor waferThe surface to which the abrasive tape is attached is fixed to a vacuum table (vacuum table), so that the back surface of the circuit surface can be ground. Then, the concentration of the solution can be adjusted to 500mJ/cm by using UV A²Or more irradiation of the back side grinding tape on the ground wafer.

Advantageous effects

According to the present invention, it is possible to provide a back grinding tape which can be easily applied to a process of grinding a wafer having a thin thickness and can prevent problems such as misalignment of a mold after grinding by maintaining creep deformation of an adhesive tape at a low level, and a method of grinding a wafer using the back grinding tape.

Detailed Description

The present invention will be described in more detail by the examples shown below. However, these examples are provided for illustrative purposes only, and the scope of the present invention is not intended to be limited to or by these examples.

[ preparation example: preparation of (meth) acrylate resin

Preparation example 1

A monomer mixture consisting of 27g of 2-ethylhexyl acrylate (2-EHA), 48g of methyl acrylate (MA, glass transition temperature 86 ℃), and 25g of hydroxyethyl acrylate (HEA) was added to a reactor equipped with a cooling system to achieve reflux of nitrogen and easy temperature control.

Then, 400ppm of n-DDM as a Chain Transfer Agent (CTA) and 100 parts by weight of ethyl acetate (EAc) as a solvent were added thereto based on 100 parts by weight of the monomer mixture, and sufficiently mixed with each other at 30 ℃ for 30 minutes or more while injecting nitrogen gas to remove oxygen from the reactor. Then, the temperature was raised to 50 ℃ and maintained at 50 ℃, 300ppm of V-70[2,2' -azobis (4-methoxy-2, 4-dimethylvaleronitrile) ] as a reaction initiator was added thereto to thereby initiate a reaction, followed by polymerization for 24 hours to prepare a first reaction substance.

24.6 parts by weight of 2-methacryloyloxyethyl isocyanate (MOI) (70 mol% based on HEA in the first reaction substance) and 1% by weight of a catalyst (dibutyltin dilaurate: DBTD L) based on MOI were mixed in the first reaction substance, and then allowed to react at 40 ℃ for 24 hours, thereby introducing ultraviolet curing groups into the branched chains of the polymer in the first reaction substance.

Preparation example 2

A (meth) acrylate-based polymer resin (weight average molecular weight: about 900000g/mol) was prepared in the same manner as in preparation example 1, except that a monomer mixture composed of 27g of 2-ethylhexyl acrylate (2-EHA) and 25g of hydroxyethyl acrylate (HEA) was added.

Examples and comparative examples: preparation of Back-grinding tape