Metal Oxide Particle Removal Using Electrolyzed Anode Water

Abstract

RCA cleaning has been intensively studied and modified for high integration and environmental requirements for the past ten years. Ozonized, hydrogenized, and electrolyzed water cleaning technologies are being developed as alternatives for fulfilling the requirements. However, their particle cleaning concept is not breaking through the RCA paradigm of double-layer repulsion. In this work, only electrolyzed anode water was applied to clean particles based on the Pourbaix concept since the anode water was very oxidative and low in pH, and as a test vehicle, MgO particles were introduced to prove the new concept. MgO particles were immersed in the anode water and their weight losses due to dissolution were measured with time. Weight losses of MgO in 250 mL anode water were in the ranges of 100-700 micrograms and it was calculated that concentrations of reactive cleaning radicals in the anode water were at least in the range of 1 ϫ 10 18 ea/cm 3 . Hence it is realized that the anode water can be applied to the display and semiconductor cleaning since at most 1 ϫ 10 10 -1 ϫ 10 15 at/cm 2 ranges of contaminations are being dealt with in their processes. Also, it was observed that the anode water affected the surface conditions of silicon wafer. It does not develop microroughness on the hydrophobic silicon surface while it does on the native silicon oxide on silicon wafer even though it is known from the Pourbaix diagram that the normal silicon oxide or glass cannot be attacked by the anode water. This is believed to be due to the chemical instability of the native silicon oxide. It is conclusively issued that the anode water application may be very crucial even for nanoparticle cleaning because the nanoparticle removal concept is not based on the double-layer repulsion but rather the dissolution-like metal removal.

Silicon Surface Morphology after Annealing in Ambient Hydrogen Containing a Trace Amount of Hydrogen Halide Gas

“…For manufacturing microelectronic devices, a very flat silicon surface is necessary. Thus, many researchers studied the microroughness of silicon surface in relation to various processes and characterizations, such as wet cleaning, [1][2][3] epitaxial growth, [4][5][6] rapid thermal processing, 7) removing photoresist, 8) silicon wafer bonding, 9) surface characterization, 10,11) and gate oxide integrity. [12][13][14][15][16] Various important devices necessary for information technology and power electronics are produced from the silicon epitaxial wafer.…”