Segmented Collimator Arrangement for Plasma Optical Interrogation

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Solution Overview

Problem

Existing plasma processing systems face challenges with optical viewport deposition or etching, leading to increased system downtime and difficulty in separating signal intensity changes due to plasma properties from changes in window transmittance, especially when high aspect ratio collimators are impractical or costly to manufacture.

Innovation Solution

A collimator arrangement with a plurality of collimators separated by a connecting region, allowing for independent machining and alignment to achieve a high effective aspect ratio, reducing viewport conditioning and off-axis light collection while maintaining optical signal intensity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If a single long collimator with high aspect ratio is used, then the angle of acceptance is reduced and viewport conditioning is minimized, but the manufacturing cost and complexity increase significantly

Engineering Contradiction:

Improveviewport conditioningVSAvoidcollimator manufacturing complexity

Core Design Contradiction:

Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The collimator is divided into multiple separate collimator sections (first collimator section, second collimator section, etc.) that can be manufactured independently and then assembled. Each section has a manageable aspect ratio while the combined assembly achieves the desired high effective aspect ratio, reducing individual manufacturing complexity while maintaining the protective function against viewport conditioning.

Inventive Principle:

Principle #1Segmentation

2Object-affected harmful factors

If a single long collimator with high aspect ratio is used, then the angle of acceptance is reduced, but the manufacturing cost and practical feasibility decrease

Engineering Contradiction:

Improveangle of acceptanceVSAvoidcollimator manufacturing feasibility

Core Design Contradiction:

Object-affected harmful factorsVSEase of manufacture

Solution Approach 1:

The collimator is segmented into multiple manageable sections that can be manufactured using standard machining processes. Each section has a practical aspect ratio that is feasible to manufacture, while the assembled configuration achieves the required low angle of acceptance through the cumulative effect of multiple sections in series.

Inventive Principle:

Principle #1Segmentation

3Ease of manufacture

If multiple collimators are assembled together, then the effective aspect ratio increases and manufacturing becomes more practical, but the alignment precision requirements increase

Engineering Contradiction:

Improvecollimator manufacturing practicalityVSAvoidcollimator alignment precision

Core Design Contradiction:

Ease of manufactureVSManufacturing precision

Solution Approach 1:

The collimator is divided into multiple sections that can be manufactured separately with standard tolerances. The segmentation is designed so that each section contributes to the overall high effective aspect ratio while being manufacturable with practical precision requirements, avoiding the need for a single extremely precise long collimator.

Inventive Principle:

Principle #1Segmentation

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 effectively protects the viewport from plasma species, reduces system downtime, and increases the mean time between failures (MTBF) for optical components, while being cost-efficient and practical in manufacturing.

Implementation Method 1

collecting optical signals, through the collimator arrangement, from the plasma within the plasma processing chamber

Methodology Applied

Scientific EffectLight transmission: Light

Implementation Method 2

resulting in highly collimated optical signals

Methodology Applied

Scientific EffectCollimation:

Implementation Method 3

The collimator arrangement is configured with a plurality of collimators, wherein a first collimator of the plurality of collimators is separated by a connecting region from a second collimator in the plurality of collimators

Methodology Applied

Scientific EffectPhysical barrier blocking:

Data Source

PatentUS7907260B2Collimator arrangements including multiple collimators and implementation methods thereof

Publication Date: 2011.03.15 LAM RES CORP

AI summary

A method for optical interrogation of plasma during plasma processing in a plasma processing chamber is provided. The method includes providing an optical viewport. The method also includes providing a collimator arrangement. The collimator arrangement is configured with a plurality of collimators, wherein a first collimator of the plurality of collimators is separated by a connecting region from a second collimator in the plurality of collimators. The method further includes collecting optical signals, through the collimator arrangement, from the plasma within the plasma processing chamber while a substrate is being processed, resulting in highly collimated optical signals.