Semiconductor Surface Inspection via Diffracted Light Optimization
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional surface inspecting methods for semiconductor wafers, particularly for hole patterns, often fail to achieve optimal inspection conditions due to difficulties in determining the most effective azimuth angles for diffraction analysis, leading to suboptimal defect detection sensitivity and increased risk of receiving diffracted light from lower layers or incorrect pattern orientations.
Innovation Solution
A surface inspecting method and apparatus that sets the irradiation direction of illumination light to match the repeating arrangement direction of hole patterns, rather than line patterns, and performs simulations based on design and shape measurement information to maximize the change in diffracted light, ensuring optimal inspection conditions for defect detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional inspection methods use fixed azimuth angles (0 or 90 degrees) for diffraction analysis, then the inspection process is simple, but the defect detection sensitivity is insufficient and false positives from lower layers occur
Solution Approach 1:
The patent performs preliminary simulations using design information and shape measurement information to determine optimal inspection conditions before actual inspection. By pre-calculating the irradiation direction that maximizes diffracted light change for the specific hole pattern pitch and shape, the system avoids trial-and-error during inspection, thereby improving detection sensitivity without proportionally increasing operational complexity
Solution Approach 2:
The patent changes the inspection parameters by determining optimal irradiation directions based on the specific pitch and shape of hole patterns rather than using fixed azimuth angles. The simulation varies the irradiation direction parameter to find the condition that maximizes the change in diffracted light, thereby improving measurement precision for defect detection
2Reliability
If the irradiation direction is not optimized for hole patterns, then the inspection setup is straightforward, but diffracted light from lower layers is received causing false positives
Solution Approach 1:
The patent applies local quality by tailoring the inspection conditions specifically to the hole pattern characteristics (pitch and shape) rather than using universal fixed-angle inspection. The optimal irradiation direction is locally optimized for each pattern type, maximizing the diffracted light change signal from the target pattern while minimizing signals from lower layers, thereby improving reliability
Solution Approach 2:
The patent uses design information (a theoretical copy of the intended pattern) and shape measurement information (a measured copy of the actual pattern) to simulate and determine optimal inspection conditions. By copying the pattern geometry into simulation models, the system can predict optimal irradiation directions without physical trial-and-error, improving reliability while managing complexity
3Measurement precision
If traditional inspection methods are used for high-density patterns, then the process is simple, but detection sensitivity decreases due to smaller pitch and complex arrangements
Solution Approach 1:
For high-density patterns with small pitch and complex arrangements, the patent performs preliminary simulations using design information and shape measurement information to determine optimal inspection conditions before actual inspection. This advance preparation identifies the specific irradiation direction that maximizes diffracted light change for the particular high-density pattern configuration, enabling sensitive detection without overwhelming operational complexity during inspection
Solution Approach 2:
The patent adapts inspection parameters by determining optimal irradiation directions based on the specific pitch and shape characteristics of high-density hole patterns. The simulation varies the irradiation direction parameter to find the condition that maximizes the change in diffracted light for the particular high-density arrangement, thereby improving measurement precision for challenging patterns
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 enables more sensitive and accurate defect detection in hole patterns by optimizing the inspection conditions, reducing false positives from lower layers and improving detection sensitivity, especially in high-density pattern manufacturing where traditional methods struggle.
Implementation Method 1
detecting diffracted light corresponding to a pitch of the hole pattern from the surface irradiated with the illumination light
Data Source
AI summary
Provided is a surface inspecting method for inspecting a surface of a semiconductor substrate having linear line patterns repeatedly arranged and hole-shaped hole patterns formed on the line patterns. The surface inspecting method includes setting inspecting conditions; irradiating the surface of the semiconductor substrate with illumination light under the set inspecting conditions; detecting diffracted light from the semiconductor substrate irradiated with illumination light; and judging existence/nonexistence of a defect in the hole patterns, based on the detected diffracted light. The inspecting conditions are to be set so that the irradiating direction of the illumination light on the surface of the semiconductor substrate is different from the repeated arrangement direction of the line patterns and substantially matches the repeated arrangement direction of the hole patterns.