Localized Wafer Thinning Using Laser Ablation to Reduce Warpage

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Conventional wafer thinning methods, especially for thinning SiC wafers used in power and RF devices, result in high breakage ratios and significant warpage issues when the wafer thickness is reduced below 100 μm, making handling and subsequent processes difficult.

Innovation Solution

A localized laser thinning process that involves image recognition and localized laser processing based on die features to thin specific regions of the wafer, reducing warpage and breakage by selectively thinning areas of interest.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Volume of moving object

If conventional grinding methods are used to thin the entire backside of the wafer, then the wafer thickness is reduced, but the wafer warpage increases and breakage ratio increases

Engineering Contradiction:

Improvewafer thicknessVSAvoidwafer warpage

Core Design Contradiction:

Volume of moving objectVSStability of the object's composition

Solution Approach 1:

The patent applies localized laser thinning to specific regions of the wafer backside rather than uniform thinning. The laser processing is concentrated in the central region where epitaxial layers create stress, while leaving the peripheral region with original thickness to provide structural support and reduce warpage. This local quality differentiation resolves the contradiction between achieving thinness and maintaining stability.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The wafer backside is divided into different processing zones: a central region that is thinned by laser ablation and a peripheral region that retains original thickness. This segmentation allows different parts of the wafer to serve different functions - the thinned central region reduces stress from epitaxial layers while the thicker peripheral region provides mechanical support, thus reducing overall warpage.

Inventive Principle:

Principle #1Segmentation

2Volume of moving object

If wafer thickness is reduced below 100 μm, then device performance is improved, but handling difficulty increases and breakage ratio increases

Engineering Contradiction:

Improvewafer thicknessVSAvoidbreakage ratio

Core Design Contradiction:

Volume of moving objectVSReliability

Solution Approach 1:

The wafer is processed with non-uniform thickness distribution - the central region is thinned to below 100 μm to improve device performance, while the peripheral region maintains greater thickness to provide mechanical strength and reduce breakage during handling. This local quality approach allows the wafer to simultaneously achieve both performance improvement and reliability.

Inventive Principle:

Principle #3Local quality

3Stability of the object's composition

If the middle portion of the wafer backside is thinned using a smaller grinding wheel, then warpage is reduced, but supporting stress in the thinned region becomes insufficient

Engineering Contradiction:

Improvewafer warpageVSAvoidsupporting stress

Core Design Contradiction:

Stability of the object's compositionVSStrength

Solution Approach 1:

The patent replaces conventional mechanical grinding with laser ablation for wafer thinning. Laser processing provides more precise and controlled material removal, creating a smoother thickness transition zone that reduces stress concentration. This substitution of processing method allows for better control of the thinning process, maintaining structural integrity while reducing warpage.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 localized laser thinning process effectively reduces wafer warpage and breakage, enabling precise thickness control and improved handling of wafers, particularly for SiC wafers used in power and RF devices.

Implementation Method 1

performing localized laser thinning processing on a bottom surface of the wafer within the at least one to-be-thinned starting region of each of the plurality of dies by a laser apparatus

Methodology Applied

Scientific EffectLaser ablation: Laser Ablation

Data Source

PatentUS20250385136A1System for localized wafer thinning and method thereof

Publication Date: 2025.12.18 DEUVTEK CO LTD

AI summary

A method for localized wafer thinning, comprising following steps of: providing a wafer including a plurality of dies; for each of the plurality of dies, determining at least one interested feature related to at least one device formed on a top surface of the wafer and at least one to-be-thinned starting region according to the at least one interested feature; capturing at least one image of each of the plurality of dies; performing image recognition on the at least one image to recognize the at least one interested feature of each of the plurality of die; and performing localized laser thinning processing on a bottom surface of the wafer within the at least one to-be-thinned starting region of each of the plurality of dies, such that the wafer is locally thinned.