Effect of Bias Frequency on Bottom-Up SiO₂ Gap-Filling Using Plasma-Enhanced Atomic Layer Deposition

Area of Science:

• Materials Science
• Semiconductor Manufacturing
• Plasma Physics

Background:

• Next-generation 3D semiconductor devices require high-aspect-ratio (HAR) patterns.
• Void and seam formation during gap-filling of HAR patterns, like deep trenches, is a significant challenge, especially at the nanoscale.

Purpose of the Study:

• To investigate the effect of bias power frequency on SiO2 trench gap-filling using plasma-enhanced atomic layer deposition (PEALD) with ion collision.
• To achieve void-free, bottom-up gap-filling in HAR patterns.

Main Methods:

• Utilized a SiO2 PEALD process with substrate bias power for ion collision.
• Systematically varied the bias power frequency to study its impact on trench gap-filling.
• Analyzed the formation of overhangs and the deposition profile within trenches.

Main Results:

• Bias power frequency did not significantly alter the SiO2 process rate (growth per cycle).
• Low bias frequencies led to overhang formation at trench entrances via sputtering and redeposition, blocking the pattern.
• High-frequency bias power prevented overhang formation.
• Ion scattering within the trench resulted in thicker deposition at the bottom, enabling bottom-up filling.

Conclusions:

• Optimizing bias power frequency in PEALD is crucial for void-free gap-filling of HAR patterns.
• High-frequency bias power effectively suppresses overhang formation, allowing for successful bottom-up deposition.
• This method is promising for fabricating advanced 3D semiconductor devices.