Wafer Grinding Segmentation for Peripheral Chipping

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

The existing grinding processes for thinning wafers are prone to processing failures such as chipping and cracking at the outer peripheral portion during coarse grinding, leading to increased grinding time due to reduced removal amounts and slower progress in finish grinding to avoid these failures.

Innovation Solution

A processing method that involves coarse grinding with large abrasive grains to thin the workpiece, followed by an auxiliary grinding step to create an unground region at the outer peripheral portion, and then finish grinding with smaller abrasive grains to remove this region, allowing for increased feed rates and reduced processing failures.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If coarse grinding with large abrasive grains is performed to quickly thin the workpiece, then productivity is improved, but processing failures such as chipping and cracking occur at the outer peripheral portion

Engineering Contradiction:

Improvegrinding speedVSAvoidprocessing failure rate

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The grinding process is segmented into three distinct stages: coarse grinding for rapid material removal, auxiliary grinding to create an unground region at the outer periphery, and finish grinding for precision finishing. This segmentation allows each stage to optimize for its specific function, preventing processing failures while maintaining high productivity

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The auxiliary grinding step performs a preliminary action by intentionally leaving an unground region at the outer peripheral portion before finish grinding. This preliminary action prevents the large abrasive grains from directly contacting and damaging the outer periphery during coarse grinding, thereby preventing chipping and cracking

Inventive Principle:

Principle #10Preliminary action

2Reliability

If the removal amount by coarse grinding is reduced to suppress processing failures, then reliability is improved, but the grinding time increases

Engineering Contradiction:

Improveprocessing failure rateVSAvoidgrinding time

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

By segmenting the grinding process into coarse, auxiliary, and finish grinding stages, the patent allows coarse grinding to operate at high removal rates without concern for outer periphery damage, while the auxiliary and finish grinding stages handle the precision and quality requirements, thus maintaining both high productivity and reliability

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The auxiliary grinding step acts as an intermediary between coarse and finish grinding. It creates a transition zone (unground region) that protects the outer periphery from direct contact with large abrasive grains, serving as a mediator that enables high-rate coarse grinding while preventing processing failures

Inventive Principle:

Principle #24Intermediary (Mediator)

3Reliability

If finish grinding is performed after the workpiece is thinned to suppress processing failures, then processing failure rate is reduced, but the progress of grinding becomes slow

Engineering Contradiction:

Improveprocessing failure rateVSAvoidgrinding progress

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The patent segments the grinding process so that coarse grinding handles the bulk material removal with high productivity, while auxiliary and finish grinding handle the outer periphery with high precision. This segmentation ensures that finish grinding is not delayed until after significant thinning, but rather occurs in a controlled manner on the unground region, maintaining both productivity and reliability

Inventive Principle:

Principle #1Segmentation

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

This method shortens the grinding time while suppressing processing failures at the outer peripheral portion by using larger abrasive grains for initial thinning and smaller grains for finish grinding, optimizing the removal process.

Implementation Method 1

The grinding apparatus grinds and thins the workpiece by rotating the grinding wheel and bringing the rotating grinding stones into contact with the workpiece

Methodology Applied

Scientific EffectAbrasion: Abrasion

Data Source

PatentUS12064847B2Processing method of workpiece

Publication Date: 2024.08.20 DISCO CORP

AI summary

There is provided a processing method of grinding a workpiece. The processing method includes a holding step of holding the workpiece on a side of its front surface on a chuck table, a coarse grinding step of grinding the workpiece on a side of its back surface with first grinding stones until the workpiece has a predetermined thickness, an auxiliary grinding step of grinding the workpiece on the side of its back surface with the first grinding stones such that an unground region remains at an outer peripheral portion of the workpiece, an unground region grinding step of grinding the unground region with second grinding stones having an average abrasive grain size smaller than that of the first grinding stones, and a finish grinding step of grinding the workpiece on the side of its back surface with the second grinding stones until the workpiece has a predetermined finish thickness.