Wafer Edge Exposure Apparatus Using Segmented Reticle Patterns

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Solution Overview

Problem

Current wafer edge exposure methods, such as chemical edge bead removal and wafer edge exposure, face challenges like long processing times, high solvent consumption, irregular edge trimming, and damage to valid dies due to concentric ring exposure patterns, which affect the yield and quality of semiconductor devices.

Innovation Solution

A wafer edge exposure apparatus and method that includes a wafer carrying module, reticle, alignment module, and exposure module, where the reticle is shaped to match the valid region of the wafer, allowing precise alignment and exposure of the edge region without damaging the valid area, using a control module to synchronize the movement of the wafer and reticle for accurate edge exposure.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If concentric ring exposure pattern is used for wafer edge exposure, then the edge region can be exposed, but the valid region will be partially exposed causing damage to valid dies

Engineering Contradiction:

Improveedge exposure precisionVSAvoidvalid die integrity

Core Design Contradiction:

Manufacturing precisionVSReliability

Solution Approach 1:

The patent divides the exposure process into two distinct stages: first exposing only the edge region using a customized reticle with edge region pattern, then exposing the interior region using a standard reticle with interior region pattern. This segmentation prevents overlap exposure that would damage valid dies while ensuring complete coverage of the edge region.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent applies different exposure patterns to different regions of the wafer. The edge region receives exposure through a customized reticle with specific edge patterns, while the interior region receives exposure through standard reticles. This local differentiation ensures that the edge region is properly exposed without affecting the validity of the interior dies.

Inventive Principle:

Principle #3Local quality

2Loss of substance

If chemical edge bead removal is used, then photoresist can be removed from wafer edge, but the process takes long time and consumes high solvent

Engineering Contradiction:

Improvephotoresist removal effectivenessVSAvoidedge removal efficiency

Core Design Contradiction:

Loss of substanceVSProductivity

Solution Approach 1:

The patent replaces the chemical edge bead removal process with an optical exposure method. Instead of using chemical solvents to remove photoresist from the edge, the system uses light exposure through a customized reticle to selectively expose the edge region, achieving photoresist removal without chemical consumption and with faster processing.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Loss of substance

If chemical edge bead removal is used, then photoresist can be removed from wafer edge, but the edge trimming becomes irregular affecting yield

Engineering Contradiction:

Improvephotoresist removal effectivenessVSAvoidedge trimming uniformity

Core Design Contradiction:

Loss of substanceVSManufacturing precision

Solution Approach 1:

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent uses a customized reticle that contains a precise pattern matching the desired edge region geometry. This reticle acts as a template or copy of the target edge shape, ensuring that the exposure is applied uniformly and precisely to the edge region, eliminating the irregularity problems associated with chemical methods.

Inventive Principle:

Principle #26Copying

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 solution ensures accurate and efficient removal of photoresist from the wafer edge, avoiding damage to the valid region and improving the product yield by precisely controlling the exposure process.

Implementation Method 1

the alignment detection units are configured to detect the alignment state of the reticle with the wafer

Methodology Applied

Scientific EffectOptical detection: Light

Implementation Method 2

the control module is configured to control the exposure module to perform wafer edge exposure on the wafer

Methodology Applied

Scientific EffectPhoto exposure: Photopolymerisation

Data Source

PatentUS11822261B2Wafer edge exposure apparatus, wafer edge exposure method and photolithography device

Publication Date: 2023.11.21 CHANGXIN MEMORY TECH INC

AI summary

A wafer edge exposure apparatus includes a wafer carrying module, a reticle, a reticle driving module, an alignment module, an exposure module, and a control module; the wafer carrying module is configured to carry the wafer and drive the wafer to rotate; the wafer includes a valid region and an edge region surrounding the valid region; the reticle driving module is configured to drive the reticle to rotate; the alignment unit is configured to detect the alignment state of the reticle with the wafer; and the control module is configured to control the movement state of the wafer carrying module and the reticle driving module and configured to control the exposure module to perform wafer edge exposure on the wafer.