Nonequilibrium activated dissociative chemisorption: SiH4 on Si(100)

Area of Science:

• Chemical Engineering
• Materials Science
• Physical Chemistry

Background:

• Gas-surface interactions are crucial for chemical vapor deposition (CVD) processes.
• Understanding the kinetics of silane (SiH4) decomposition on silicon surfaces is key for optimizing silicon film growth.
• Non-equilibrium conditions in CVD can significantly alter surface reaction pathways.

Purpose of the Study:

• To analyze and predict the dissociative sticking coefficients of SiH4 on Si(100) under various non-equilibrium conditions.
• To determine the threshold energy for SiH4 dissociative chemisorption.
• To model a strategy for enhancing silicon CVD rates at low surface temperatures.

Main Methods:

• A three-parameter local hot spot model was utilized to simulate gas-surface reactivity.
• A 15-dimensional microcanonical kinetics approach was employed, considering active degrees of freedom including surface oscillators, molecular vibrations, rotations, and translational energy.
• Calculations were performed under varied non-equilibrium conditions.

Main Results:

• The threshold energy for SiH4 dissociative chemisorption was determined to be 19 kJ/mol.
• The model demonstrated quantitative agreement with recent GGA-DFT calculations.
• A simple scheme for increasing silicon CVD rates from SiH4 at low surface temperatures was successfully modeled.

Conclusions:

• The local hot spot model provides an accurate framework for predicting SiH4 sticking coefficients on Si(100).
• The identified threshold energy is a critical parameter for understanding and controlling SiH4 chemisorption.
• The proposed method offers a potential pathway for efficient low-temperature silicon deposition.