Colorimeter Metrology for Semiconductor Layer Thickness
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Solution Overview
Problem
Conventional metrology methods are inadequate for accurately measuring the thin thickness of semiconductor layers in photovoltaic devices, particularly those grown using atomic layer deposition (ALD), as they rely on optical interference which is not effective for very thin window/emitter layers.
Innovation Solution
A colorimeter metrology system is employed to measure layer thickness by analyzing absorbance and color properties, utilizing a processor with a look-up table to correlate hue and saturation of reflected light with layer thickness, and integrating a closed-loop feedback control system for real-time deposition control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional metrology methods based on optical interference are used, then measurement can be performed, but measurement precision deteriorates for very thin semiconductor layers
Solution Approach 1:
The invention changes the measurement parameters from optical interference-based methods to colorimetric methods based on absorbance. By measuring absorbance at specific wavelengths and converting to thickness through calibration curves, the system achieves reliable measurements for very thin layers (5-50 nm) where optical interference methods fail.
Solution Approach 2:
The invention replaces the optical interference measurement system with a colorimetric measurement system using a colorimeter. This substitution enables accurate thickness measurement of thin semiconductor layers by measuring light absorbance properties rather than relying on optical interference patterns.
2Manufacturing precision
If real-time feedback control is implemented, then manufacturing precision improves, but device complexity increases
Solution Approach 1:
The invention implements a closed-loop feedback control system where the colorimeter measures layer thickness in real-time during deposition, and the deposition process is automatically adjusted based on these measurements. This feedback mechanism maintains manufacturing precision while managing system complexity through automated control.
Solution Approach 2:
The system performs preliminary calibration by measuring absorbance of known thickness samples to generate calibration curves before actual deposition. This preliminary action establishes the relationship between absorbance and thickness, enabling accurate real-time control without requiring complex theoretical models during deposition.
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 precise measurement and real-time feedback control of ALD layer thickness, ensuring accurate deposition and enhancing the yield and performance of photovoltaic devices.
Implementation Method 1
A colorimeter metrology system is employed to measure layer thickness by analyzing absorbance and color properties
Implementation Method 2
Photovoltaic devices convert the energy of sunlight directly into electricity by the photovoltaic effect
Data Source
AI summary
Described herein is a method and apparatus for measuring the thickness of a deposited semiconductor material. A colorimeter has an optical source that illuminates a portion of a deposited semiconductor material with optical radiation, a sensor that collects and measures color information related to reflected radiation from the deposited semiconductor material, and a processor that receives the color information related to the reflected radiation from the sensor and calculates a thickness of the semiconductor material. The processor may control a semiconductor material deposition apparatus.