Semiconductor Wafer Defect Detection via Differential Signal Analysis
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Solution Overview
Problem
Conventional defect inspection methods for semiconductor wafers are inefficient and costly due to the need for advanced optical and calculation equipment, as they require comparing extensive image data from different regions of the wafer, leading to prolonged detection times and high costs, especially with the increasing integration and complexity of semiconductor devices.
Innovation Solution
A method and apparatus that irradiate a bare object and a processed object with light, generating differential signals by differentiating the reflection signals from both, allowing for defect detection without requiring image comparison, using a light source, light receiver, differentiation operator, and detector to identify signal deviations indicative of processing defects on the semiconductor substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional image comparison methods are used for defect inspection, then measurement precision can be achieved, but device complexity and cost increase significantly
Solution Approach 1:
The patent extracts only the necessary reflection signal information from the wafer surface by comparing signals from different regions, rather than processing complete images. This extraction approach maintains defect detection capability while eliminating the need for complex optical imaging systems, directly resolving the contradiction between measurement precision and device complexity
Solution Approach 2:
Instead of using complex optical systems to capture images and then comparing them, the patent inverts the approach by directly measuring reflection signals and comparing signal intensities. This inversion simplifies the optical path and equipment while maintaining the ability to detect defects through signal differentiation
2Measurement precision
If conventional image comparison methods are used for defect inspection, then measurement precision can be achieved, but loss of time increases due to extensive data comparison
Solution Approach 1:
The patent extracts only the essential reflection signal intensities from specific wafer regions, avoiding the time-consuming processing and comparison of complete images. By extracting and comparing only the necessary signal parameters, the inspection process is significantly accelerated while maintaining defect detection accuracy
Solution Approach 2:
The patent performs partial action by measuring reflection signals from only the necessary regions of the wafer (inspection region and reference region) rather than analyzing the entire wafer surface. This partial measurement approach reduces inspection time while maintaining sufficient precision for defect detection
3Measurement precision
If advanced optical equipment is used for defect inspection, then measurement precision improves, but manufacturing cost increases
Solution Approach 1:
The patent extracts the essential measurement function from complex optical imaging systems, using only simple reflection signal detection. By extracting and utilizing only the necessary signal information, the system achieves adequate measurement precision with significantly reduced equipment costs and simplified manufacturing
Solution Approach 2:
The patent replaces expensive, sophisticated optical equipment with simpler, more affordable signal detection components. The system uses basic reflection measurement capabilities rather than advanced imaging systems, reducing manufacturing cost while maintaining functional effectiveness for defect inspection
4Measurement precision
If complete image data is compared for defect detection, then measurement precision is maintained, but productivity decreases due to extensive processing
Solution Approach 1:
The patent extracts only the critical reflection signal parameters from the wafer surface, avoiding the generation and processing of complete image data. This extraction methodology maintains defect detection precision while dramatically reducing computational load and increasing inspection throughput
Solution Approach 2:
The patent performs partial action by measuring and comparing reflection signals from specific regions only, rather than processing complete wafer images. This partial data approach reduces computational complexity and increases productivity while maintaining sufficient measurement precision for quality control
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
Enables efficient and reliable detection of processing defects on semiconductor wafers by analyzing differential signals, reducing the need for high-cost equipment and time-consuming comparisons, thus improving manufacturing throughput and reducing costs.
Implementation Method 1
a first light is irradiated onto a bare object, and a first reflection signal is reflected from the bare object
Data Source
AI summary
In a method of inspecting an object, a first light is irradiated onto a bare object and a first reflection signal is reflected from the bare object. A second light is irradiated onto a processed object and a second reflection signal is reflected from the processed object. The first and second reflection signals are differentiated, to thereby generate respective first and second differential signals. A defect on the processed object is detected by a comparison between the first and second differential signals. The first and second differential signals overlap with each other and at least one signal-deviation portion is detected. The first and second differential signals are spaced apart out of an allowable error range in the signal-deviation portion. The defect is detected from a portion of the processed object corresponding to the signal-deviation portion.