Anti-static Protective Sheet for Semiconductor Wafer Grinding

Solution Overview

Problem

Conventional surface protective sheets used in semiconductor wafer backside grinding fail to prevent wafer curvature and provide sufficient anti-static ability, leading to potential damage from static charges generated during the grinding process.

Innovation Solution

A surface protective sheet comprising an adhesive layer, a support film, and an anti-static coat layer with inorganic conductive fillers and a cured product of a curable resin, which has a stress relaxation rate of 60% or more and a Young's modulus of 100 to 2000 MPa, effectively dispersing static charges and preventing wafer curvature.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Stability of the object's composition

If a surface protective sheet with high stress relaxation rate is used to prevent wafer curvature, then wafer flatness is improved, but static charge accumulates causing circuit damage

Engineering Contradiction:

Improvewafer flatnessVSAvoidstatic charge

Core Design Contradiction:

Stability of the object's compositionVSObject-affected harmful factors

Solution Approach 1:

The base is divided into two functional layers: a support film providing mechanical strength and stress relaxation, and an anti-static coat layer dissipating static charge. This segmentation allows each layer to specialize in one function, resolving the contradiction between preventing curvature and reducing static charge.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The base combines a support film (providing stress relaxation) with an anti-static coat layer containing inorganic conductive filler (dissipating static charge). This composite structure integrates both required functions into a single component, simultaneously achieving wafer flatness and static charge prevention.

Inventive Principle:

Principle #40Composite materials

2Object-affected harmful factors

If an anti-static coat layer is added to the surface protective sheet, then static charge is reduced, but the sheet causes wafer curvature

Engineering Contradiction:

Improvestatic chargeVSAvoidwafer flatness

Core Design Contradiction:

Object-affected harmful factorsVSStability of the object's composition

Solution Approach 1:

The base is divided into two functional layers: a support film providing mechanical strength and stress relaxation, and an anti-static coat layer dissipating static charge. This segmentation allows each layer to specialize in one function, resolving the contradiction between preventing curvature and reducing static charge.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different parts of the base have different properties: the support film has high stress relaxation rate (60% or more) for maintaining flatness, while the anti-static coat layer has conductive properties for charge dissipation. This local differentiation of properties allows both functions to coexist without conflict.

Inventive Principle:

Principle #3Local quality

3Adaptability or versatility

If the base material is made thinner to accommodate thinner wafers, then adaptability to thin wafers is improved, but the base loses mechanical strength

Engineering Contradiction:

Improveadaptability to thin wafersVSAvoidbase strength

Core Design Contradiction:

Adaptability or versatilityVSStrength

Solution Approach 1:

The base combines a support film (providing stress relaxation) with an anti-static coat layer containing inorganic conductive filler (dissipating static charge). This composite structure integrates both required functions into a single component, simultaneously achieving wafer flatness and static charge prevention.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The support film is designed with specific mechanical parameters: stress relaxation rate of 60% or more and Young's modulus of 100 to 2000 MPa. These parameter specifications ensure the film has sufficient strength and flexibility to handle thin wafers without breaking or causing curvature.

Inventive Principle:

Principle #35Parameter changes

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The solution effectively suppresses wafer curvature and prevents damage from static charges, ensuring the integrity of the semiconductor wafer circuit during and after grinding.

Implementation Method 1

an anti-static coat layer including an inorganic conductive filler and a cured product of a curable resin (A)

Methodology Applied

Scientific EffectElectrical conduction: Conduction (electrical)

Implementation Method 2

a stress relaxation rate of the base after 1 minute of 10% stretch is 60% or more

Methodology Applied

Scientific EffectStress relaxation: Stress Relaxation

Implementation Method 3

a stress relaxation rate of the base after 1 minute of 10% stretch is 60% or more, and a Young's modulus of the base is 100 to 2000 MPa

Methodology Applied

Scientific EffectViscoelasticity: Viscoelasticity

Data Source

PatentUS10224230B2Surface protective sheet

Publication Date: 2019.03.05 LINTEC CORP

AI summary

A surface protective sheet is used when grinding the rear surface of a semiconductor wafer having a circuit formed on the front surface, and is provided with: a base material comprising a support film and an antistatic coating layer which includes an inorganic conductive filler and a cured product of a curable resin (A); and an adhesive layer. The stress relaxation percentage of the base material after 1 minute at 10% elongation is at least 60%. The Young's modulus of the base material is 100-2000 MPa.