Spectroellipsometric method for process monitoring semiconductor thin films and interfaces

Area of Science:

• Materials Science
• Thin Film Technology
• Optical Metrology

Background:

• Plasma-deposited microcrystalline silicon (μc-Si) is crucial for electronic devices.
• Controlling layer thickness and crystallinity is essential for device performance.
• Real-time monitoring during deposition is needed for process optimization.

Purpose of the Study:

• To develop a real-time monitoring technique for μc-Si growth.
• To model and analyze the inhomogeneity within the μc-Si layer.
• To enable precise control over layer thickness and crystallinity.

Main Methods:

• Utilized multiwavelength phase-modulated ellipsometry for real-time monitoring.
• Employed the WKBJ method to approximate the reflection coefficient, accounting for layer inhomogeneity.
• Applied Bruggeman effective medium theory to describe the optical properties of μc-Si.

Main Results:

• Successfully monitored the crystallinity in both upper and lower parts of the μc-Si layer.
• Achieved simultaneous monitoring of layer thickness and crystallinity.
• Demonstrated fast inversion algorithms with calculation times under 5 seconds on a standard computer.

Conclusions:

• The developed method allows for precise, real-time control of μc-Si layer thickness and crystallization.
• This technique is applicable for optimizing the fabrication of devices such as solar cells and thin-film transistors.