Papers by Author: Tadahiro Ohmi

Abstract: As technology node progressing, ultra low-k film has been implemented to reduce RC delay in LSI circuit. A fluorocarbon (CFx) film is proposed as foreground ultra low-k film because of non-porous structure [1]. Although CFx film is expected to be stable for its structure advantage, damage-less process is anticipated to avoid dielectric constants change in subsequence process steps [2]. CMP and post CMP process are concerned to bring damage on devices, so the effect of post CMP cleaning solutions on CFx structure and electric property is evaluated.

Abstract: Brush scrubbing has been widely used in post chemical mechanical planarization (CMP) applications to remove contaminations, such as slurry residues and particles, from the wafer surface. During brush scrubbing, particle removal results from direct contact between a soft poly vinyl alcohol (PVA) brush and the wafer surface in which the brush asperities engulf the particles while the rotating motion of the brush, as well as the cleaning fluid at the surface, dislodge and carry the particles away from the wafer. The cleaning performance of brush scrubbing depends heavily on the choice of the cleaning solution and brush scrubber kinematics. In this work, the effect of various cleaning solutions and brush scrubber kinematics on the frictional attributes of post copper CMP cleaning process was investigated.

Abstract: With a progress of device dimension miniaturization, an ultraclean wafer surface is continuously increasing its importance crucial for high quality processing in Silicon Technologies [1]-[8]. Cleaning of silicon wafer surface has been accomplished by RCA wet cleaning in the past [9], where there exists high temperature processes consisting of H2SO4/H2O2/H2O, NH4OH/H2O2/H2O and HCl/H2O2/H2O treatments. Thus, RCA cleaning requires a large number of processing steps, resulting in the consumption of a huge volume of liquid chemicals and UPW, and simultaneously consuming a large volume of clean air exhaust to suppress chemical vapor from getting into the clean room. Moreover, RCA cleaning is used at high temperature and contain alkali solutions, which increase the roughness of the silicon wafer surface [10].