Feasibility study on 3-D shape analysis of high-aspect-ratio features using through-focus scanning optical microscopy

Area of Science:

• Semiconductor Manufacturing
• Optical Metrology
• Nanotechnology

Background:

• Current in-line metrologies face challenges with advanced semiconductor device scaling and novel architectures.
• Metrology and process control for three-dimensional (3-D) high-aspect-ratio (HAR) features are critical and complex.
• Need for advanced metrology solutions to maintain process control in nanomanufacturing.

Purpose of the Study:

• To investigate the feasibility of Through-Focus Scanning Optical Microscopy (TSOM) for 3-D shape analysis of HAR features.
• To evaluate TSOM's capability for analyzing both isolated and arrayed HAR features.
• To assess TSOM's potential to meet future semiconductor metrology requirements.

Main Methods:

• Utilized conventional optical microscopy to collect 3-D optical data.
• Performed simulations for trenches and holes down to the 11 nm node.
• Analyzed the capability of TSOM for single isolated and arrayed HAR features.

Main Results:

• TSOM demonstrated feasibility for 3-D shape analysis of HAR features.
• Simulations covered features down to the 11 nm node.
• TSOM allows analysis of smaller targets, saving wafer real estate.
• Sensitivity may meet or exceed International Technology Roadmap for Semiconductors (ITRS) requirements.

Conclusions:

• TSOM is a promising solution for 3-D shape analysis of HAR features in semiconductor manufacturing.
• The method offers simplicity, low cost, high throughput, and nanometer-scale sensitivity.
• TSOM is an attractive option for inspection and process monitoring in nanomanufacturing.