Development of a Single-beam Megasonic System for Nano-particle Cleaning

Abstract

A single-beam megasonic system for nano-particle cleaning which less likely cause nano-pattern damage was designed. Considering ultrasonic wave propagation, a length of quartz waveguide was decided at a uniform acoustic wave region. The anti-resonance frequency of the piezoelectric actuator was measured to be 987 kHz, which agreed well with the fabricated quartz waveguide operating frequency of 983 kHz. The acoustic pressure of the single-beam megasonic system was measured, and the averaged value increased by 89% compared with a commercially available product (named an A-type). To compare uniformity, standard deviations of acoustic pressure values were calculated, and they were lower than A-type results by 20%. These results explain our system's performance improvement in acoustic pressure distribution. In addition, particle removal efficiency (PRE) tests were performed, and 91% of particles were removed after megasonic cleaning.

Cleaning and Damage Performance of Single Wafer Cleaning Tools using Physical Removal Forces

“…3. From lateral-force AFM measurements it was found that these structures are appropriate for damage tests (7). We also used gate stack lines composed of an SiO 2 hardmask on top of poly-crystalline silicon deposited on top of SiON with an aspect ratio ~ 4 (W/H/S = 40/160/1000nm) for comparison.…”

“…Two experimental datapoints obtained with gate stack lines as damage test structures and 78nm silica particles were also added for comparison and show better damage/cleaning performance as they are lying closer to the lower-right corner of the graph. This means that a-Si lines are much more fragile, probably due to the weaker a-Si/SiO 2 interface compared to the poly-Si/SiON interface (7). Customized damage/cleaning windows can be obtained by setting specifications on the damage density and particle removal efficiency.…”