Structural characterization of poly-Si Films crystallized by Ni Metal Induced Lateral Crystallization.

Area of Science:

• Materials Science
• Nanotechnology
• Semiconductor Physics

Background:

• Polycrystalline silicon (poly-Si) films are crucial for semiconductor devices.
• Ni Metal Induced Lateral Crystallization (Ni-MILC) is a common technique for growing poly-Si films.
• Solid Phase Crystallization (SPC) often occurs in parallel with Ni-MILC at higher temperatures.

Purpose of the Study:

• To investigate the growth mechanism of poly-Si films using Ni-MILC at a lower temperature (413°C).
• To compare the film morphology and growth mode at 413°C with those grown at temperatures above 500°C.
• To understand the role of suppressed Solid Phase Crystallization (SPC) in the Ni-MILC process at low temperatures.

Main Methods:

• Amorphous silicon films were subjected to Ni-MILC at 413°C.
• Transmission Electron Microscopy (TEM) was employed to analyze the morphology and growth of the poly-Si films.
• Growth rates and crystallographic orientations of resulting silicon whiskers were characterized.

Main Results:

• At 413°C, SPC is suppressed, altering the growth mode compared to higher temperatures.
• The poly-Si films consist of two types of whiskers: fast-growing <111> oriented whiskers and slower-growing whiskers with random orientations.
• Significant orientation filtering occurs due to growth-velocity competition between whiskers.
• A uniform tweed-like structure is formed by the mixture of differently oriented whiskers.

Conclusions:

• Low-temperature Ni-MILC (413°C) effectively suppresses SPC, leading to distinct poly-Si film morphologies.
• The growth-velocity competition between differently oriented whiskers is a key factor in forming the observed tweed-like structure.
• This study provides insights into controlling poly-Si film microstructure through temperature-dependent crystallization mechanisms.