Chemically controlled megasonic cleaning of patterned structures using solutions with dissolved gas and surfactant
Bichitra Nanda Sahoo1, So Young Han1, Hyun-Tae Kim1
1Department of Materials Science and Chemical Engineering, Hanyang University, Ansan 15588, Republic of Korea.
Ultrasonics Sonochemistry
|December 30, 2021
Summary
Megasonic cleaning of silicon wafers using dissolved hydrogen and SDS surfactant optimizes particle removal while minimizing pattern damage. Bubble dynamics analysis reveals chemical influences on cleaning performance.
Area of Science:
- Materials Science
- Chemical Engineering
- Acoustics
Background:
- Megasonic cleaning is crucial in semiconductor manufacturing for delicate wafer structures.
- Controlling acoustic cavitation is key to balancing particle removal efficiency (PRE) and pattern damage (PD).
Purpose of the Study:
- To evaluate the impact of dissolved hydrogen (H2) and sodium dodecyl sulfate (SDS) concentrations on megasonic cleaning performance.
- To understand how these factors influence particle removal efficiency (PRE) and pattern damage (PD) on silicon wafers.
Main Methods:
- Investigated cleaning solutions with varying concentrations of H2 and SDS in deionized water (DIW).
- Assessed PRE and PD on silicon wafers using megasonic cleaning.
- Employed a high-speed camera to analyze bubble dynamics under ultrasonic fields.
Main Results:
- Increased H2 concentration enhanced PRE but also increased PD.
- SDS surfactant initially increased PRE in DIW, then decreased it at higher concentrations.
- SDS significantly reduced PD in both DIW and H2-DIW solutions.
- Bubble coalescence, agglomeration, and multi-bubble populations were observed to influence PRE and PD.
Conclusions:
- The study elucidates the complex interplay between dissolved gases, surfactants, and bubble dynamics in megasonic cleaning.
- Optimal concentrations of H2 and SDS can be determined to achieve high PRE and low PD for fragile semiconductor patterns.
