Exposure Apparatus Focus Control with Selective Height Points

Solution Overview

Problem

Existing exposure apparatuses face issues with focus operations being performed based on measurement results from measurement points with low repeatability, potentially leading to important regions being exposed in a defocus state.

Innovation Solution

A measurement system measures the height of a substrate at multiple points, a user interface prompts settings for using these points, and a controller controls focus operations based on these measurements to ensure accurate alignment with the projection optical system.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If focus operation is performed using measurement results from all measurement points, then comprehensive coverage is achieved, but measurement precision deteriorates due to inclusion of low repeatability points

Engineering Contradiction:

Improvefocus operation reliabilityVSAvoidheight measurement precision

Core Design Contradiction:

ReliabilityVSMeasurement precision

Solution Approach 1:

The patent applies local quality by differentiating the treatment of measurement points based on their individual characteristics. Measurement points are classified into different groups (e.g., first measurement points with higher reliability and second measurement points with lower reliability) and different processing methods are applied to each group. This allows the system to weight or select measurement results based on local quality attributes rather than treating all points uniformly.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent segments the set of measurement points into multiple categories based on repeatability characteristics. By dividing the measurement points into groups (such as using points from high-repeatability regions versus low-repeatability regions), the system can selectively combine results from different segments to optimize both reliability and precision in the focus operation.

Inventive Principle:

Principle #1Segmentation

2Area of stationary object

If measurement points from low repeatability regions are included, then complete region coverage is achieved, but focus accuracy deteriorates in important regions

Engineering Contradiction:

Improvemeasurement coverage areaVSAvoidexposure focus accuracy

Core Design Contradiction:

Area of stationary objectVSManufacturing precision

Solution Approach 1:

The patent applies local quality by differentiating the treatment of measurement points based on their individual characteristics. Measurement points are classified into different groups (e.g., first measurement points with higher reliability and second measurement points with lower reliability) and different processing methods are applied to each group. This allows the system to weight or select measurement results based on local quality attributes rather than treating all points uniformly.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent extracts and separates measurement points from low repeatability regions from the overall measurement set. By identifying and isolating measurement points that are likely to degrade focus accuracy (those from regions with low repeatability), the system can either exclude them or apply different weighting, thereby preventing them from negatively impacting the focus operation in important regions while still maintaining comprehensive coverage where applicable.

Inventive Principle:

Principle #2Taking out (Extraction)

Data Source

PatentUS20250271773A1Exposure apparatus, control method therefor, information processing apparatus, information processing method, non-transitory computer readable medium, and article manufacturing method

Publication Date: 2025.08.28 CANON KK

AI summary

An exposure apparatus for exposing an exposure region of a substrate by projecting a pattern of an original to the exposure region by a projection optical system, includes a measurement system configured to measure a height of the substrate at each of a plurality of measurement points in the exposure region, a user interface configured to prompt a user to make a setting concerning use of each of the plurality of measurement points, and a controller configured to control a focus operation of the exposure region with respect to an image plane of the projection optical system by using a measurement result of the measurement system based on the setting.