Optical Metrology for Damaged Semiconductor Wafer Structures
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Solution Overview
Problem
Conventional optical metrology systems struggle to accurately measure damaged structures on semiconductor wafers, as they fail to account for stochastic effects such as damaged materials, which can lead to inaccurate profile determination and quality assessment.
Innovation Solution
A method involving the calculation of a simulated diffraction signal for a hypothetical damaged periodic structure, allowing for the comparison with a measured diffraction signal to determine the extent of damage by defining a profile with undamaged and damaged portions, and using this comparison to establish the damage amount.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional optical metrology is used to measure structures on semiconductor wafers, then the measurement process is simple and fast, but the measurement precision deteriorates when damaged structures are present due to unaccounted stochastic effects
Solution Approach 1:
The structure profile is segmented into multiple portions (first portion, second portion, third portion) with different damage characteristics. Each portion is measured and analyzed separately to determine its specific damage amount, allowing for precise characterization of damaged structures without requiring a complete redesign of the measurement system.
Solution Approach 2:
Damage assessment is performed preliminarily during the optical metrology measurement process itself, before final quality determination. The method identifies and quantifies damage in different structure portions during the initial measurement, enabling early detection and accurate profiling of damaged structures.
2Reliability
If conventional optical metrology measures structures without accounting for damage, then the measurement process is straightforward, but the reliability of quality assessment deteriorates
Solution Approach 1:
The measurement system applies local quality analysis by determining different damage amounts for different portions of the structure. The first portion, second portion, and third portion each have their own damage characteristics that are measured and evaluated separately, providing reliable local quality assessment rather than a single average value.
Solution Approach 2:
The patent introduces an intermediary analysis layer that processes the optical measurement data to extract damage information. By analyzing the relationship between measured properties and known damage patterns, the system mediates between raw measurements and final quality assessment, improving reliability without requiring direct complex damage detection.
3Manufacturing precision
If the structure is formed with stochastic effects causing damaged materials, then manufacturing variability increases, but the measurement system cannot distinguish between intentional profile variations and damage
Solution Approach 1:
The measurement system dynamically adapts its analysis based on detected variations. By comparing measurements across different portions and analyzing deviations from expected profiles, the system dynamically identifies which variations represent intentional design features versus damage, preserving manufacturing precision information while recovering damage data.
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 precise measurement and assessment of damage in semiconductor wafer structures, improving the accuracy of quality evaluation and process control in semiconductor manufacturing.
Implementation Method 1
Optical metrology involves directing an incident beam at a structure, measuring the resulting diffracted beam, and analyzing the diffracted beam to determine various characteristics
Data Source
AI summary
A method of measuring a damaged structure formed on a semiconductor wafer using optical metrology, the method includes obtaining a measured diffraction signal from a damaged periodic structure. A hypothetical profile of the damaged periodic structure is defined. The hypothetical profile having an undamaged portion, which corresponds to an undamaged area of a first material in the damaged periodic structure, and a damaged portion, which corresponds to a damaged area of the first material in the damaged periodic structure. The undamaged portion and the damaged portion have different properties associated with them. A simulated diffraction signal is calculated for the hypothetical damaged periodic structure using the hypothetical profile. The measured diffraction signal is compared to the simulated diffraction signal. If the measured diffraction signal and the simulated diffraction signal match within a matching criterion, then a damage amount for the damaged periodic structure is established based on the damaged portion of the hypothetical profile used to calculate the simulated diffraction signal.