Christopher Lee Timmons

Electrochemical Cleaning of Post-Plasma Etch Fluorocarbon Residues Using Reductive Radical Anion Chemistry

A process for cleaning post-etch fluorocarbon residues based on reductive radical ion chemistry has been developed and modified for use in semiconductor processing. Conventional liquid cleaning processes or oxidative processes may be incompatible with emerging low-dielectric constant materials. X-ray photoelectron spectroscopy results indicate that radical anion solutions, based on sodium-naphthalenide, are capable of defluorinating model fluorocarbon etch residues at a rate of 27 nm/min. To eliminate sodium, which is a semiconductor contaminant, radical naphthalene ions can be generated electrochemically without sodium. Comparable defluorination of fluorocarbon materials was observed. A selective carbon-carbon bond cleavage using aqueous ozone was necessary to complete the removal of the defluorinated residue. Semiconductor process compatibility was evaluated using three interlevel dielectric materials. Both silicon dioxide and Coral demonstrated good chemical and etch resistance to the process. Minimal oxidation of methylsilsesquioxane was observed during the ozone treatments.

Photoresist and Fluorocarbon Postplasma Etch Residue Removal Using Electrochemically Generated Radical Anions

Integration of new materials into semiconductor manufacturing sequences demands cleaning processes that are compatible with copper and low dielectric constant (low-k) materials. Conventional oxidative cleaning processes are currently used to remove fluorocarbon-based postplasma etch residues; however, these processes are generally incompatible with organic-containing low-k candidate materials. A photoresist removal and etch residue cleaning process based on reductive naphthalene radical anion chemistry has been developed and evaluated on patterned low-k etch residue samples. Solutions of naphthalene radical anions are generated by electrolysis using platinum electrodes in a split electrochemical cell. The radical anion process cleans effectively at room temperature and thus requires no elevated temperature steps for film removal or surface drying. The removal mechanism is a synergistic combination of solvent swelling and fluorocarbon attack, resulting in effective etch-residue removal; removal from vias as small as 130 nm has been demonstrated. Preliminary investigations indicate chemical compatibility with both Coral and methylsilsesquioxane low-k materials.

Photoresist Removal Using Alternative Chemistries and Pressures

Approximately 20% of the processing steps in integrated circuit (IC) fabrication involve surface cleaning and removal of photoresist and plasma etch residues. Continuous device minimization requires the use of thin films (<20 nm), closely spaced features, and ultra shallow junctions (<50nm); as a result, the challenges associated with effective surface cleaning are intensified. In addition, to insure high device performance, incorporation of alternate materials such as copper, ruthenium, and molybdenum, porous low dielectric constant SiO2-based insulators, and hafnium or zirconium oxides or silicates into device structures is taking place. Integration of these materials into working devices requires precise control of surface properties. In order to eliminate damage to films or substrates, avoid modification of surfaces, promote contaminant removal rates and enhance process control, approaches such as use of downstream plasmas, liquid cleaning with low concentrations of reactive chemicals, mechanical agitation, and liquid or particle jets have been implemented [1].

Particulate Generation Mechanisms during Bulk Filling and Mitigation via New Glass Vial

Contamination with foreign particulate matter continues to be a leading cause of parenteral drug recalls, despite extensive control and inspection during manufacturing. Glass is a significant source of particulate matter contamination; however, the mechanism, source, and quantification have not been extensively analyzed. Quantification of particulate matter generation with lab simulations suggests that glass-to-glass contact on the filling line produces large quantities of glass particles of various sizes. A new strengthened glass vial with a low coefficient of friction surface is proposed to address this root cause of glass particle generation. Lab simulations and two line trials using this new vial demonstrated a substantial reduction of glass particulate generation, of resulting product contamination, as well as of the frequency of required filling line interventions. These results suggest that substantial reductions in particulate matter contamination of all types, glass and non-glass, can be achieved through the use of a new glass vial designed to effectively eliminate a root cause of glass particle generation. LAY ABSTRACT: Contamination with foreign particulate contamination continues to be a leading cause of injectable drug recalls, despite extensive control and inspection during manufacturing. Glass particles are one of the most common types of particulate identified; however, the generation mechanism has not been extensively studied. Lab simulations suggest that routine glass-to-glass contact of vials during the filling process results in large quantities of glass particulate. A new, strengthened glass vial with a low coefficient of friction surface is proposed to address this mechanism. Lab simulations and multiple filling line trials demonstrated a substantial reduction of glass particulate matter generation and product contamination with use of the new vial. These results suggest that this new vial reduces contamination risk by eliminating a root cause of glass particulate generation.