Pulse Scoring for Correlating Plasma States With Wafer Metrology
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Solution Overview
Problem
Existing pulsed plasma processes in semiconductor fabrication lack direct correlation between pulse quality metrics and process results such as etching rate and critical dimension, making it difficult to develop effective process control and optimization applications.
Innovation Solution
A method of pulse scoring is introduced, which involves executing a plasma process pulsed between two states, collecting in-situ data, and processing these data to obtain pulse features. These features are analyzed with metrology data to determine interaction terms that correlate with process outcomes, allowing for the prediction of wafer characteristics using virtual metrology models.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If pulse quality metrics are measured during plasma processes, then process monitoring capability is improved, but direct correlation with process results such as etching rate and critical dimension remains insufficient
Solution Approach 1:
The patent introduces pulse scores as an intermediary metric that bridges pulse quality measurements and process results. The pulse score is calculated by integrating plasma power, electron density, and ion flux measurements during the pulse, creating a composite metric that directly correlates with etching rate and critical dimension. This intermediary transforms multiple raw measurements into a single predictive metric that loses minimal information while enabling direct correlation with process outcomes.
Solution Approach 2:
The pulse score functions as a composite metric combining multiple plasma parameters (power, electron density, ion flux) into a single correlated measure. Similar to composite materials combining different substances to achieve superior properties, the pulse score combines multiple measurements to achieve superior predictive capability for process results, directly addressing the correlation deficiency.
2Reliability
If traditional plasma process monitoring is used, then process control is maintained, but turnaround time for optimization cycles remains long
Solution Approach 1:
The patent implements preliminary action by calculating pulse scores in real-time during the plasma process itself, rather than waiting for post-process metrology. The pulse score is computed continuously from in-situ measurements, allowing optimization decisions to be made during or immediately after the process, dramatically reducing the optimization cycle time while maintaining reliable process control through the correlated metric.
3Measurement precision
If in-situ sensors are deployed to collect plasma data, then real-time monitoring is improved, but data processing complexity increases
Solution Approach 1:
The patent extracts only the essential plasma parameters (power, electron density, ion flux) needed for pulse score calculation from the wealth of data available from in-situ sensors. Rather than processing all sensor data, the system selectively extracts and integrates these three key parameters, significantly reducing data processing complexity while maintaining the ability to generate predictive pulse scores in real-time.
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
The pulse scoring method enables more efficient process control and optimization by providing clear, correlated metrics for plasma processes, reducing the turnaround time for optimization cycles and improving the reliability of predictions.
Implementation Method 1
plasma processing plays a vital role in material deposition and removal in the production of semiconductor chips. Typical examples include plasma-assisted chemical vapor deposition, plasma-assisted physical vapor deposition, plasma etching, plasma cleaning
Data Source
AI summary
A method of pulse scoring is provided. The method includes executing a plasma process pulsed between a first state and a second state. In-situ data measured by in-situ sensors are collected while the plasma process is being executed. The in-situ data are processed to obtain first pulse features of the first state and second pulse features of the second state. Metrology data are collected after executing the plasma process. The first pulse features, the second pulse features and the metrology data are analyzed to determine pulse scores that are interaction terms of the first pulse features and the second pulse features and have correlations above a target threshold with the metrology data in regression analysis.