Pan Guoshun

Effect of pH on Material Removal Rate of Cu in Abrasive-Free Polishing

The effect of pH on the material removal rate (MRR) of Cu in an organic phosphonic acid system abrasive-free slurry was investigated by thermodynamics, X-ray photoelectron spectroscopy analysis, and electrochemical measurements. The pH range can be divided into three chemical regions according to the evolution of the polishing MRR, which relies on the effect of pH on the chelating effect of the chelating ligand, diethylene triamine penta methylene phosphonic acid. The higher the pH is, the more efficient the chelating ligand is. In the alkaline pH region, because of the enhanced chelating effect and precipitation of the chelate complex on the surface, both the MRR and friction coefficient during polishing process increase significantly, and the corrosion current acquired from the potentiodynamic polarization measurement decreases.

CMP of GaN using sulfate radicals generated by metal catalyst

A method for preparing atomically smooth gallium nitride (GaN) surface with high material removal rate that involves chemical mechanical polishing with sulfate radical (SO4-) oxidizer and Fe2+ activator in slurry is presented. The results indicate that complexing agent with Fe2+ activator is the key point to obtain atomically smooth GaN surface and higher removal rate of GaN. Atomic force microscope (AFM) shows that the average surface roughness (Ra) is 0.0601nm.

Chemical Mechanical Polishing of Copper in Organic Phosphonic Acid System Slurry

Chemical mechanical polishing behavior of copper in organic phosphonic acid system shiny with ammonium persulfate as oxidizer was studied, including the effect of different organic phosphonic acids, concentration of oxidizer and also pH value of slurry. Results showed that there is an optimized concentration value for each kinds of organic phosphonic acid to get maximum material removal rate. With the increasing of pH value, material removal rate also increases, especially when conies into alkaline scope. Shiny with 10mM Dietliylene Triamine Penta Methylene Phosphonic Acid and 3% ammonium persulfate gives the best polishing performance with a too high material removal rate as about 2000 nm/min. With appropriate additives, the material removal rate can be restricted in an acceptable value as below 800 nm/min, and the surface profile is also improved.