Wafer Weighing Support Layout for Precise Mass Measurement

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Solution Overview

Problem

Semiconductor wafers that are not flat or not supported level during weight measurement can lead to inaccurate weight readings due to edge deviations and electrostatic forces, which affect the precision of mass change measurements.

Innovation Solution

A weighing device with a support system that contacts the wafer underside less than D/3 from its edge to stabilize the wafer during measurement, ensuring accurate weight readings by maintaining a level orientation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If the wafer is supported at the center during weight measurement, then the support structure is simple, but the measurement precision deteriorates due to edge deviations and electrostatic forces

Engineering Contradiction:

Improvesupport structure complexityVSAvoidweight measurement precision

Core Design Contradiction:

Device complexityVSMeasurement precision

Solution Approach 1:

The support structure is segmented into multiple contact elements (at least three) positioned at specific locations on the balance pan, rather than using a single centralized support point. This segmentation allows the wafer to be supported at multiple points closer to the edge, stabilizing the wafer and reducing edge deviations while maintaining structural simplicity

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The contact elements are positioned at specific radial distances from the center (between 0.15R and 0.4R) and at specific angular positions (at least 120 degrees apart), transitioning from a single-point support to a distributed multi-point support system in both radial and angular dimensions, thereby improving measurement precision without significantly increasing complexity

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Measurement precision

If the contact elements are positioned close to the wafer edge, then the measurement precision improves by reducing edge uncertainties, but the device complexity increases

Engineering Contradiction:

Improveweight measurement precisionVSAvoidsupport structure complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

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 solution provides stable support for curved or bowed wafers, reducing edge uncertainties and electrostatic interference, resulting in precise mass measurements.

Implementation Method 1

to support the wafer during a weight measurement

Methodology Applied

Scientific EffectGravitational force: Gravitation

Implementation Method 2

the support comprises a plurality of contact elements configured to contact an underside of the wafer to support the wafer

Methodology Applied

Scientific EffectNormal force: Mechanical Force

Implementation Method 3

reducing edge uncertainties and electrostatic interference

Methodology Applied

Scientific EffectElectrostatic force: Electrostatics

Data Source

PatentEP4490474B1Weighing device for a semiconductor wafer

Publication Date: 2025.12.10 METRYX

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AI summary

An apparatus comprising: a measurement chamber, wherein the measurement chamber has a removable lid; and a plurality of wafer support elements for supporting a wafer from beneath, wherein the plurality of wafer support elements are provided on the lid.