Contactless Gap Measurement in Constrained Plasma Chambers

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Solution Overview

Problem

Existing systems struggle to accurately measure the gap between a workpiece and a nearby object in a plasma processing chamber due to dimensional constraints and the need for non-invasive, precise positioning, especially in semiconductor manufacturing where misalignment can lead to yield loss and product defects.

Innovation Solution

A contactless system using low-profile assemblies with electromagnetic beam projection and imaging sensors to determine the gap between a workpiece and an object, capable of operating in constrained environments, including a central control unit and low-profile assemblies that project beams onto the object's surface to calculate the gap based on beam spot positions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If contactless measurement systems are used to precisely measure the gap between workpiece and focus ring, then measurement precision is improved, but device complexity increases due to the need for electromagnetic beam projection and imaging sensors in a constrained plasma chamber environment

Engineering Contradiction:

Improvegap measurement precisionVSAvoidsystem complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent replaces mechanical contact-based measurement systems with a contactless electromagnetic beam-based measurement system. The system uses electromagnetic beams (laser or other radiation) projected onto the focus ring surface, with imaging sensors detecting the beam spot positions to calculate gap distances, eliminating the need for physical contact probes or mechanical gauges in the plasma chamber.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent introduces electromagnetic beams as an intermediary medium to transfer measurement information from the focus ring to the imaging sensors. The beams act as a mediator that carries spatial information about the focus ring position and gap dimensions without requiring direct physical contact between measurement devices and the workpiece or focus ring.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Manufacturing precision

If the workpiece surface is leveled to the top of the focus ring to improve plasma uniformity, then plasma processing uniformity is improved, but measurement difficulty increases because the gap becomes harder to detect

Engineering Contradiction:

Improveplasma processing uniformityVSAvoidgap detection difficulty

Core Design Contradiction:

Manufacturing precisionVSDifficulty of detecting and measuring

Solution Approach 1:

The patent employs electromagnetic radiation (visible light or other wavelengths) that interacts with the focus ring surface, producing detectable optical signals. The imaging sensors detect changes in light intensity, reflection, or absorption patterns at different positions, enabling the system to distinguish the focus ring edge and calculate gap distances even when the workpiece surface is flush with the focus ring top.

Inventive Principle:

Principle #32Color changes

Solution Approach 2:

The patent replaces direct mechanical or optical contact measurement methods with a contactless electromagnetic beam projection and detection system. This allows measurement of the gap between workpiece and focus ring without physical interference, working effectively even when the surfaces are leveled to eliminate fringing effects.

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

Enables precise measurement of the gap between a workpiece and an object, even when the workpiece surface is level with the nearby object, ensuring accurate positioning and reducing errors in semiconductor fabrication processes.

Implementation Method 1

a projector for projecting an electromagnetic beam onto a surface of an object to produce a beam spot on the object surface

Methodology Applied

Scientific EffectElectromagnetic radiation: Light

Implementation Method 2

an imaging sensor array placed at the image plane and coupled with the image processor to determine a position of the image of the beam spot on the image plane

Methodology Applied

Scientific EffectPhotoelectric detection: Photoelectric Effect

Data Source

PatentUS20260017819A1Methods and systems for contactless object measurement

Publication Date: 2026.01.15 SHANGHAI GND ETECH CO LTD

AI summary

Provided are system and method for contactless precision measurement of the position of the system relative to a nearby object. The system comprises a workpiece, at least one low-profile assembly, and a central control unit. The low-profile assembly comprises a main axis directed to a first direction and approximately parallel to the surface of the workpiece to intersect the inner surface of the object. The assembly further comprises at least one projector for projecting an electromagnetic beam onto the object for the measurement. Both the low-profile assembly and the central control unit are attached on the surface of the workpiece at desired locations. The system can be operated stand alone in an enclosed and dimensional constrained operation environment.