Dry surface cleaning using CO2 snow

Abstract

Controlled expansion of high purity carbon dioxide through a nozzle forms a high velocity ‘‘snow’’ stream that effectively removes both particulate and thin film contaminants from silicon wafer surfaces [W. Whitlock, Presented at the 20th Annual Meeting of the Fine Particle Society, Boston, MA, August 22, 1989 (unpublished); R. Sherman and W. Whitlock, J. Vac. Sci. Technol. B 8, 563 (1990)]. This process will clean surfaces leaving no detectable film residue as well as reduce adventitious (native) hydrocarbon surface content. This article discusses the performance of CO2 snow cleaning on a variety of materials typically encountered in a surface analysis laboratory. Cleaning tests were performed on metals (aluminum and copper sheets), semiconductors (Si and InP wafers), and insulators (ceramics, laser optics, glass plates, and polymers). Performance is judged primarily through x-ray photoelectron spectroscopy measurements with primary consideration given to reduction of surface hydrocarbons. These measurements are compared with samples which were cleaned with a conventional solvent process. The results indicate that CO2 snow cleaning is comparable to solvent cleaning in its effectiveness for removal of hydrocarbon films. Recommendations are made for the use of CO2 snow cleaning in both industrial and laboratory applications.

Static SIMS studies of carboxylic acids on gold and aluminium–magnesium alloy surfaces

“…Carbon dioxide snow cleaning was also attempted: this involved the direction of a high-speed jet of carbon dioxide gas, containing small dry ice particles, at the Al-Mg alloy surface. 39 The combination of sonication in methylene chloride followed by 45 min of UV/ozone treatment resulted in the lowest percentage of surface carbon on the cleaned surfaces, as measured by XPS. Approximately 80% of the uncleaned alloy surface was composed of hydrocarbon residues.…”

Fabrication of a Current-Perpendicular to Plane Magneto-resistive Device with a Dry Ice Blasting Lift-off Process

“…Therefore, it is hard to define the process conditions. Dry ice blasting is a unique method as a surface cleaner in semi-conductor manufacturing 1,2) . The cleaning system basically consists of nozzle with narrow orifice which nozzle is connected with high pressurized CO2 (gas or liquid) cylinder.…”

Effective removal of field-emitting sites from metallic surfaces by dry ice cleaning

“…12 Dry ice cleaning ͑DIC͒ is a powerful technique which uses a high-pressure jet of pure carbon dioxide snow to loosen and remove different types of particulate contaminations from the surface by its unique combination of thermal, mechanical, and chemical effects. [13][14][15][16] The rapid cooling at the point of hitting brittles the particulates, thus weakening the adhesion for their efficient removal by the impact of snow particles. Unlike HPR, this technique significantly removes hydrocarbon contaminations from the cleaned surfaces, 13 since carbon dioxide is a good solvent for nonpolar chemicals.…”