Wafer Edge Support Layer for Crack-Resistant Back Grinding

Solution Overview

Problem

Conventional wafer grinding methods result in weak edges and potential cracking due to insufficient structural support at the wafer edge, leading to chipping and cracking during handling.

Innovation Solution

A wafer grinding method that includes forming a patterned photoresist or thermosetting material layer on the annular peripheral area of the wafer to provide edge support, followed by attaching a back grinding tape and performing a back grinding process on the back side of the wafer base.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Length of moving object

If the wafer is ground to reduce size and provide thinner profiles, then the semiconductor device size is reduced, but the wafer edge becomes sharp and weak, leading to cracking and chipping

Engineering Contradiction:

Improvewafer thicknessVSAvoidwafer edge strength

Core Design Contradiction:

Length of moving objectVSStrength

Solution Approach 1:

The method applies preliminary action by forming a patterned photoresist or thermosetting material layer on the annular peripheral area of the wafer before the grinding process. This pre-formed layer provides structural support to the wafer edge during subsequent grinding operations, preventing the edge from becoming sharp and weak. The support layer is applied in advance to counteract the weakening effect that would otherwise occur during thickness reduction.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The invention applies local quality by providing targeted support only to the annular peripheral area where the wafer edge is located, while leaving the solder ball area exposed. The patterned layer is formed with specific spatial distribution - covering the peripheral region that requires strength reinforcement during grinding, but not covering the active solder ball region. This localized approach strengthens the wafer edge without interfering with the functional solder ball area.

Inventive Principle:

Principle #3Local quality

2Productivity

If conventional grinding methods are used without edge support, then the grinding process is simple and fast, but the wafer edge is susceptible to cracking and chipping during handling

Engineering Contradiction:

Improvegrinding process efficiencyVSAvoidwafer edge integrity

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The method applies preliminary action by forming a patterned photoresist or thermosetting material layer on the annular peripheral area of the wafer before the grinding process. This pre-formed layer provides structural support to the wafer edge during subsequent grinding operations, preventing the edge from becoming sharp and weak. The support layer is applied in advance to counteract the weakening effect that would otherwise occur during thickness reduction.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The invention applies local quality by providing targeted support only to the annular peripheral area where the wafer edge is located, while leaving the solder ball area exposed. The patterned layer is formed with specific spatial distribution - covering the peripheral region that requires strength reinforcement during grinding, but not covering the active solder ball region. This localized approach strengthens the wafer edge without interfering with the functional solder ball area.

Inventive Principle:

Principle #3Local quality

3Strength

If a patterned support layer is formed on the wafer edge, then the wafer edge strength is reinforced, but the process complexity increases

Engineering Contradiction:

Improvewafer edge strengthVSAvoidmanufacturing process complexity

Core Design Contradiction:

StrengthVSDevice complexity

Solution Approach 1:

The method employs a disposable patterned layer made of photoresist or thermosetting material that is applied temporarily to the wafer edge, serves its protective function during grinding, and can be removed afterward. This temporary structure provides the necessary edge support without requiring permanent, complex modifications to the wafer or equipment. The layer is inexpensive and single-use, eliminating the need for complex, expensive, or permanent structural modifications.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

Solution Approach 2:

The patterned photoresist or thermosetting material layer acts as an intermediary element between the wafer edge and the grinding process. Rather than directly modifying the wafer structure or the grinding equipment, this intermediate layer provides the necessary mechanical support during the critical grinding operation. The intermediary layer can be easily applied and removed, simplifying the overall process compared to permanent structural modifications.

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS20260001190A1Wafer grinding methods

Publication Date: 2026.01.01 STATS CHIPPAC LTD

AI summary

A wafer grinding method comprises: providing a wafer base comprising a front side and a back side, wherein the front side comprises a solder ball area and an annular peripheral area surrounding the solder ball area; forming a patterned photoresist layer on the front side of the wafer base, wherein the patterned photoresist layer at least partially covers the annular peripheral area but exposes the solder ball area; forming solder balls on the solder ball area; attaching a back grinding tape on the front side to cover both the solder ball area and the annular peripheral area; and performing a back grinding process on the back side of the wafer base.