Pre-polymerized Protective Layer for Semiconductor Wafer Warpage

Solution Overview

Problem

Semiconductor wafer warpage increases with larger die sizes and thinner dies, affecting the stacking and handling of multiple semiconductor dies in multi-chip packages due to compressive stress from polymer buffer coat films formed during the curing process.

Innovation Solution

A pre-polymerized protective layer is applied to the semiconductor wafer, which is already in a polymerized state, eliminating further shrinkage and stress on the wafer, and patterned to expose bonding pads and facilitate die separation without inducing warpage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a polymer buffer coat film is formed during the curing process, then protective coverage is provided, but compressive stress and warpage increase

Engineering Contradiction:

Improveprotective coverageVSAvoidcompressive stress

Core Design Contradiction:

ReliabilityVSStress or pressure

Solution Approach 1:

The polymer buffer coat film is pre-formed and cured on a separate carrier substrate before being transferred to the semiconductor wafer. This preliminary curing action allows the polymer to complete its polymerization and shrinkage process beforehand, preventing subsequent stress development on the semiconductor wafer while maintaining protective coverage.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

A carrier substrate serves as an intermediary medium where the polymer buffer coat film is initially formed and cured. This intermediary approach separates the polymer formation process from the semiconductor wafer, allowing stress-free transfer of the pre-cured protective film to the wafer surface.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If a polymer buffer coat film is formed during the curing process, then protective coverage is provided, but warpage increases

Engineering Contradiction:

Improveprotective coverageVSAvoidwarpage

Core Design Contradiction:

ReliabilityVSShape

Solution Approach 1:

The polymer buffer coat film is pre-formed and cured on a separate carrier substrate before being transferred to the semiconductor wafer. This preliminary curing action allows the polymer to complete its polymerization and shrinkage process beforehand, preventing subsequent stress development on the semiconductor wafer while maintaining protective coverage.

Inventive Principle:

Principle #10Preliminary action

3Productivity

If die thickness is reduced, then integration density increases, but warpage increases

Engineering Contradiction:

Improveintegration densityVSAvoidwarpage

Core Design Contradiction:

ProductivityVSShape

Solution Approach 1:

The pre-cured polymer buffer coat film acts as a cushioning layer that compensates for the reduced mechanical strength and increased warpage susceptibility of thinner dies. By providing this protective layer before stacking, the system maintains structural integrity despite reduced die thickness.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

4Adaptability or versatility

If die size is increased, then functional capacity increases, but warpage increases

Engineering Contradiction:

Improvefunctional capacityVSAvoidwarpage

Core Design Contradiction:

Adaptability or versatilityVSShape

Solution Approach 1:

The pre-cured polymer buffer coat film acts as a cushioning layer that compensates for the reduced mechanical strength and increased warpage susceptibility of thinner dies. By providing this protective layer before stacking, the system maintains structural integrity despite reduced die thickness.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

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 reduces mechanical stress on the semiconductor wafer, minimizing warpage and improving the ability to stack and handle multiple dies in multi-chip packages by applying a stress-free pre-polymerized protective layer that maintains its shape and structure.

Implementation Method 1

attaching the polymerized material layer to the semiconductor wafer

Methodology Applied

Scientific EffectAdhesion: Adhesive

Implementation Method 2

etching portions of the polymerized material layer that are proximal to the openings through the etch mask layer by applying an etchant into the openings through the etch mask layer in an etch process

Methodology Applied

Scientific EffectChemical etching:

Data Source

PatentUS11538777B2Semiconductor structure containing pre-polymerized protective layer and method of making thereof

Publication Date: 2022.12.27 SANDISK TECHNOLOGIES LLC

AI summary

A method of forming a semiconductor structure includes providing a semiconductor wafer including a plurality of semiconductor dies, providing a polymerized material layer, attaching the polymerized material layer to the semiconductor wafer such that the polymerized material layer is polymerized prior to the step of attaching the polymerized material layer to the semiconductor wafer, applying and patterning an etch mask layer over the polymerized material layer, such that openings are formed through the etch mask layer, etching portions of the polymerized material layer that are proximal to the openings through the etch mask layer by applying an etchant into the openings through the etch mask layer in an etch process, and removing the etch mask layer selective to the polymerized material layer. Alternatively, a patterned polymerized material layer may be transferred from a transfer substrate to the semiconductor wafer.