Resist Pattern Inspection for Semiconductor Surface Defect Detection
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Solution Overview
Problem
Conventional inspection methods for semiconductor wafers falsely detect grain boundaries as defects, leading to re-evaluation by site-operators and reduced throughput.
Innovation Solution
A method involving the formation of a resist pattern on a semiconductor wafer, where surface defects are detected by analyzing the intensity ratio of reflected light or by comparing surface images, ensuring that the focal point is aligned with the resist pattern rather than grain boundaries.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional inspection methods irradiate laser light on semiconductor wafer surface to detect foreign matter, then detection capability is provided, but grain boundaries are falsely detected as defects reducing throughput
Solution Approach 1:
A resist pattern is introduced as an intermediary layer on the semiconductor wafer surface. This resist pattern serves as a mediator that modifies the optical properties of the surface, enabling the inspection system to distinguish between actual defects and grain boundaries through enhanced light scattering characteristics.
Solution Approach 2:
The optical parameters of the wafer surface are changed by forming a resist pattern with specific optical properties. The resist pattern alters the light scattering behavior, creating distinct optical signatures that allow the inspection system to differentiate between grain boundaries (normal structures) and actual defects based on scattering intensity ratios.
2Measurement precision
If inspection system detects grain boundaries as defects, then detection sensitivity is improved, but re-evaluation by site-operators is required increasing time consumption
Solution Approach 1:
The inspection system uses feedback from the light scattering intensity ratios to automatically distinguish between grain boundaries and defects. By analyzing the characteristic scattering patterns produced by the resist pattern, the system provides feedback that enables automatic classification, eliminating the need for manual re-evaluation of false positives.
Solution Approach 2:
The resist pattern creates a standardized optical copy or template of the wafer surface structure. By comparing actual light scattering patterns against the expected pattern from the resist structure, the system can automatically identify deviations representing true defects without requiring operator intervention.
3Measurement precision
If light scattering intensity ratio method is used to detect defects, then detection capability is provided, but false detection of grain boundaries occurs
Solution Approach 1:
The resist pattern introduces local quality variations across the wafer surface that are uniform and controlled. These localized optical modifications create consistent reference points that help the inspection system distinguish between normal surface variations (grain boundaries) and abnormal defects based on deviations from the expected local pattern.
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 reduces false detection of grain boundaries, eliminates the need for re-evaluation by site-operators, and enhances visual inspection sensitivity and throughput.
Implementation Method 1
detecting a surface defect occurring in the surface electrode during the first process, either using a difference of intensities of lights reflected from the resist pattern on the surface electrode between an area thereof where the surface defect occurs and an area thereof where no surface defect occurs by irradiating light on the resist pattern
Implementation Method 2
using a comparison between a surface image of the area where the surface defect occurs and a surface image of the surface where no surface defect occurs by photographing the surface of the semiconductor wafer using a photographing mechanism
Data Source
AI summary
A resist film formed on a surface electrode is exposed and developed, thereby forming a fine resist pattern. An exposure focus is aligned with a surface of the resist film on a normal portion of the surface electrode, whereby deficient pattern portions of the resist pattern are caused on a convex defect and on a concave defect of the surface electrode. The deficient pattern portions of the resist pattern are detected either using a difference of intensities of lights reflected from the resist pattern on the surface electrode between an area thereof where the deficient pattern portion is formed and an area thereof where no surface defect occurs by irradiating light on the resist pattern, or using a comparison between a surface image of deficient pattern portion and a surface image of the surface where no surface defect occurs by photographing the surface of the semiconductor wafer.