Wafer Chuck Perimeter Support Gap Design

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Solution Overview

Problem

Conventional wafer chucks damage the active front side of wafers during backside processing due to mechanical contact, leading to defect formation and potential electrical failures, as they require the front side to be upside down, which complicates layer deposition and processing.

Innovation Solution

A wafer chuck design that supports the wafer only along its outer perimeter, maintaining a gap between the front side and the chuck to prevent mechanical contact, allowing for backside processing while keeping the front side untouched, and is compatible with various processing tools and deposition methods.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a conventional wafer chuck contacts the front side of the wafer during backside processing, then the wafer can be securely held and processed, but the front side of the wafer is damaged leading to defect formation and potential electrical failures

Engineering Contradiction:

Improvewafer processing reliabilityVSAvoidmechanical contact damage to front side

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The wafer chuck is segmented into distinct functional zones: an outer peripheral contact region that holds the wafer edge and an inner central region that remains free of contact. This segmentation allows the chuck to secure the wafer mechanically at the periphery while leaving the front side's active processing area untouched, thereby preventing mechanical damage during backside processing

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The wafer chuck applies local quality by providing contact only at specific locations (the outer perimeter/edge of the wafer) rather than across the entire surface. The contact regions are localized to the peripheral area, while the central region maintains a gap to avoid damaging the front side, thus achieving secure holding without mechanical contact damage

Inventive Principle:

Principle #3Local quality

2Adaptability or versatility

If the wafer is positioned with the front side facing away from the chuck for backside processing, then the backside can be processed, but the front side becomes vulnerable to damage from mechanical contact

Engineering Contradiction:

Improvebackside processing capabilityVSAvoidfront side damage risk

Core Design Contradiction:

Adaptability or versatilityVSObject-affected harmful factors

Solution Approach 1:

The wafer chuck inverts the conventional positioning approach by holding the wafer with its front side facing away from the chuck (toward the processing region) rather than contacting the front side directly. The chuck contacts only the peripheral edge, allowing the front side to face the processing region without mechanical contact, thus enabling backside processing while protecting the front side

Inventive Principle:

Principle #13The other way round (Inversion)

3Manufacturing precision

If a conventional wafer chuck design is used, then mechanical contact is established for secure holding, but parasitic plasma formation occurs and processing precision is reduced

Engineering Contradiction:

Improveprocessing precisionVSAvoidparasitic plasma formation

Core Design Contradiction:

Manufacturing precisionVSObject-generated harmful factors

Solution Approach 1:

The invention extracts the harmful interaction between the wafer chuck and the front side processing area by removing any contact or proximity between the chuck and the central region of the wafer. The chuck is designed to contact only the peripheral edge, extracting the source of parasitic plasma formation and enabling high-precision processing without interference

Inventive Principle:

Principle #2Taking out (Extraction)

Data Source

PatentUS11387081B2Wafer chuck and processing arrangement

Publication Date: 2022.07.12 INFINEON TECHNOLOGIES AG

AI summary

According to various embodiments, a wafer chuck may include at least one support region configured to support a wafer in a receiving area; a central cavity surrounded by the at least one support region configured to support the wafer only along an outer perimeter; and a boundary structure surrounding the receiving area configured to retain the wafer in the receiving area.