Wafer Thickness Dependent Profile Library for Optical Metrology
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Optical metrology in semiconductor manufacturing faces challenges in accurately measuring wafer profiles due to material variations across wafers and lots, caused by non-uniform films and process changes, leading to inconsistencies in optical properties and physical properties during etching processes.
Innovation Solution
The implementation of Real-Time Parameter Tuning (RTPT) procedures using Transparent Coupling Devices (TCDs) to feed-forward tuning parameters, which update models and recipes in real-time, and the creation of a thickness-dependent profile library to improve measurement accuracy by establishing a wafer-thickness-dependent profile data space and selecting the best estimate signal for measurement corrections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional optical metrology system uses a static profile library for measuring wafer structures, then the measurement process is simple and fast, but the measurement accuracy deteriorates due to material variations across wafers and lots
Solution Approach 1:
The patent implements a dynamic profile library system that adapts to real-time wafer conditions. The system determines wafer state (thickness, temperature) and selects appropriate profile data from the library based on these conditions, transforming a static measurement system into a dynamic one that adjusts to material variations across wafers and lots, thereby improving measurement accuracy without requiring complete system redesign
Solution Approach 2:
The system changes the parameters used for measurement by incorporating wafer-specific parameters (thickness, temperature, material composition) into the measurement process. By determining the actual wafer state and selecting profile data matching these parameters, the system compensates for material variations and optical property changes, improving measurement precision while maintaining operational simplicity
2Measurement precision
If the profile library is made wafer-thickness-dependent to improve measurement accuracy, then measurement precision improves, but the complexity of the measurement system increases
Solution Approach 1:
The patent segments the profile library into multiple subsets, each corresponding to specific wafer state conditions (thickness ranges, temperature ranges, material compositions). By dividing the library into condition-specific segments and selecting the appropriate segment based on real-time wafer state determination, the system improves measurement accuracy while managing complexity through organized data structure rather than monolithic system complexity
3Measurement precision
If real-time parameter tuning is implemented to account for wafer variations, then measurement accuracy improves, but the processing time increases
Solution Approach 1:
The system performs preliminary determination of wafer state (thickness, temperature, material properties) before conducting the actual optical measurement. By pre-determining these parameters and pre-selecting the appropriate profile library subset in advance, the system minimizes processing time during the measurement itself while still achieving high accuracy through condition-matched profile 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 enhances the precision and accuracy of optical measurements by accounting for real-time wafer thickness and temperature variations, leading to more accurate process control and improved measurement results, especially in smaller geometry technologies below the 65 nm node.
Implementation Method 1
One example of optical metrology involves directing an incident beam at a structure, measuring the resulting diffracted beam, and analyzing the diffracted beam to determine various characteristics, such as the profile of the structure.
Data Source
AI summary
A method for facilitating an ODP (optical digital profile) measurement of a semiconductor wafer. The method includes obtaining real time wafer characteristic data for a measurement site on the wafer and detecting a measured diffraction signal from a structure within the measurement site of the wafer. The measured diffraction signal is matched with a simulated diffraction signal stored in a wafer characteristic dependent profile library. A hypothetical profile structure associated with the simulated diffraction signal in the wafer characteristic dependent profile library is then identified. The real time wafer characteristic data is used to facilitate at least one of the matching and identifying. The real time wafer characteristic data may be real time wafer thickness data.