Scatterometry Metrology for Semiconductor Process Drift Detection
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Solution Overview
Problem
Existing semiconductor manufacturing processes struggle to accurately analyze the impact of various photolithographic parameters, such as post-bake temperature and illumination conditions, on critical dimensions, leading to difficulties in controlling semiconductor element characteristics.
Innovation Solution
A method utilizing scatterometry critical dimension metrology to measure and analyze the impact of multiple semiconductor manufacturing parameters by creating a relationship library between test line pitches and measured critical dimensions, allowing for the detection of process parameters through proximity profile error signatures and spectra analysis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If scatterometry metrology is used to measure critical dimensions, then measurement precision is improved, but the ability to detect multiple process parameters simultaneously deteriorates
Solution Approach 1:
The patent segments the measurement process into multiple distinct steps: first measuring critical dimensions to establish a baseline relationship, then measuring the same structures under different process conditions to detect parameter drifts. This segmentation allows the system to maintain high measurement precision while gaining the ability to detect multiple process parameters by comparing results across different measurement sessions.
Solution Approach 2:
The patent performs preliminary measurements under known process conditions to establish a reference relationship between critical dimensions and process parameters. This preliminary action creates a baseline that enables subsequent detection of process parameter changes without requiring direct measurement of each parameter, thus maintaining measurement precision while expanding detection capability.
2Device complexity
If limited process parameters are analyzed, then device complexity is reduced, but the ability to control semiconductor element characteristics deteriorates
Solution Approach 1:
The patent implements a feedback mechanism where critical dimension measurements are continuously taken and compared against reference values. When drifts are detected, the system provides feedback about which process parameters have changed, enabling operators to adjust manufacturing conditions. This feedback loop allows comprehensive parameter analysis without proportionally increasing system complexity, as the same measurement infrastructure is used for both monitoring and control.
Solution Approach 2:
The patent leverages changes in process parameters (such as exposure energy, post-bake temperature, and illumination conditions) and measures their impact on critical dimensions. By systematically varying and measuring these parameters, the system achieves comprehensive control of semiconductor element characteristics using the existing measurement apparatus, avoiding the need for additional complex equipment for each parameter analysis.
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 accurate detection and modification of process drifts in semiconductor manufacturing, improving the control of critical dimensions and enhancing the reliability of semiconductor products by analyzing the effects of photolithographic parameters on proximity behavior.
Implementation Method 1
The major principle of scatterometry is that the intensity of incident light of the periodic gratings varies with the incident angle or with the wavelength of the incident light and the relationship between reflectance and angle/wavelength can be recorded as different signatures.
Data Source
AI summary
A method for detecting semiconductor-manufacturing conditions includes providing a photomask with a plurality of pattern areas each having a plurality of test lines with different pitches, exposing a plurality of wafer with the photomask in different manufacturing conditions, measuring the critical dimensions of the plurality of pattern areas, generating a library of relationships between the pitches and the critical dimension of the pattern areas, exposing a test wafer in an unknown manufacturing condition, finding out a relationships between the pitches and the critical dimension of the pattern areas of the test wafer, searching for a most similar relationship in the library, and detecting a set of manufacturing parameters used to expose the test wafer.