Wafer Mounting Abnormality Detection via Optical Pattern Analysis

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Solution Overview

Problem

Existing substrate processing systems face challenges in accurately detecting abnormalities in the mounting state of wafers on heat plates due to foreign substances, leading to inconsistent temperature distribution and critical dimension variations in resist patterns.

Innovation Solution

A substrate processing apparatus and method that includes a development part, a heat plate, a distribution acquisition part for optically measuring the size distribution of pattern dimensions, and a determination part to assess the mounting state based on the acquired size distribution, enabling precise detection of abnormalities.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If temperature monitoring is used to detect foreign substances on the heat plate, then detection capability is improved, but detection accuracy deteriorates when foreign substance height is small

Engineering Contradiction:

Improvedetection accuracyVSAvoiddetection reliability

Core Design Contradiction:

Measurement precisionVSReliability

Solution Approach 1:

The patent replaces the mechanical/thermal detection method (temperature monitoring) with an optical measurement method. The optical measurement unit measures the distance between the heat plate surface and the wafer back surface using light, enabling detection of even small foreign substances that cause minimal temperature changes. This substitution of detection principle resolves the contradiction by providing high detection accuracy for small foreign substances while maintaining reliable abnormality detection.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Temperature

If wafer is heated on heat plate with foreign substance, then heating function is achieved, but temperature distribution uniformity deteriorates

Engineering Contradiction:

Improveheating effectivenessVSAvoidtemperature distribution uniformity

Core Design Contradiction:

TemperatureVSStability of the object's composition

Solution Approach 1:

The patent performs preliminary detection of foreign substances on the heat plate before wafer heating using optical measurement. By detecting the distance between the heat plate surface and wafer back surface before heating occurs, the system can identify and alert operators to foreign substance contamination, preventing subsequent non-uniform heating. This preliminary action resolves the contradiction by maintaining temperature distribution uniformity while preserving heating effectiveness.

Inventive Principle:

Principle #10Preliminary action

3Reliability

If CD variation is used as indicator of mounting abnormality, then abnormality detection is achieved, but detection timing deteriorates to after pattern formation

Engineering Contradiction:

Improveabnormality detection capabilityVSAvoiddetection timing

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The patent implements preliminary detection of mounting abnormalities by measuring the distance between the heat plate surface and wafer back surface immediately after wafer placement and before heating and pattern formation. This early detection capability identifies mounting abnormalities at the source, enabling immediate corrective action and preventing downstream defects. The principle resolves the contradiction by achieving reliable abnormality detection while eliminating time loss associated with post-processing detection.

Inventive Principle:

Principle #10Preliminary action

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 approach allows for highly accurate detection of mounting abnormalities, ensuring consistent critical dimensions and improving the reliability of substrate processing by identifying and addressing issues related to foreign substances on the heat plate.

Implementation Method 1

a heat plate that heats a substrate having a resist film formed thereon, before development

Methodology Applied

Scientific EffectHeating: Heating

Implementation Method 2

a distribution acquisition part configured to optically acquire a size distribution of a dimension of the pattern on the surface of the substrate

Methodology Applied

Scientific EffectOptical measurement: Light

Data Source

PatentUS11430704B2Substrate processing apparatus, substrate processing method, and storage medium

Publication Date: 2022.08.30 TOKYO ELECTRON LTD

AI summary

A substrate processing apparatus, including: a development part configured to develop a substrate on which an exposed resist film formed to form a pattern on a surface of the substrate; a heat plate configured to mount and heat the substrate on which the resist film formed on the heat plate before the development is performed; a distribution acquisition part configured to optically acquire a size distribution of a dimension of the pattern on the surface of the substrate; and a determination part configured to determine whether abnormality has occurred in a mounting state of the substrate on the heat plate, based on the size distribution of the dimension of the pattern.