Accession Number : ADD016239

Title :   Method for Laser-Assisted Silicon Etching Using Halocarbon Ambients.

Descriptive Note : Patent, Filed 12 Dec 91, patented 30 Nov 93,

Corporate Author : DEPARTMENT OF THE NAVY WASHINGTON DC

Personal Author(s) : Russell, Stephen D ; Sexton, Douglas A ; Orazi, Richard J

Report Date : 30 Nov 1993

Pagination or Media Count : 23

Abstract : An etching process allows a selective single-step patterning of silicon devices in a noncorrosive environment. The etching of silicon relies on a maskless laser-assisted technique in a gaseous halocarbon ambient, such as the gaseous chlorofluorocarbons, dichlorodifluoromethane and chloropentafluoroethane. Laser-assisted photothermal chemical etching reactions on silicon occur in these ambients when the incident fluence from an excimer laser at 248 nm exceeds the melt threshold (approximately 0.75 J/ sq cm) When incident fluence exceeds the ablation threshold (approximately 2.2 J/ sq cm) an undesirable, increased surface roughness is observed. Etch rates as large as approximately 15 angstroms per pulse are attained within predetermined processing windows. This provides a means for thin membrane formation in silicon, rapid etches and processing of packaged devices or partially fabricated dies.

Descriptors :   *CARBON, *ETCHING, *LASERS, *SILICON, *PATENTS, ABLATION, CHEMICALS, DICHLORODIFLUOROMETHANE, ENVIRONMENTS, FLOW, EXCIMERS, MELTS, MEMBRANES, PROCESSING, HYDROCARBONS, GASES, PULSES, RATES, ROUGHNESS, SURFACE ROUGHNESS, SURFACES, WINDOWS, PRESSURE, PATTERNS, ADSORPTION, CORROSION RESISTANCE, METHANE, LIGHT, CHLORINE, FLUORINE, ETHANES, DIES, HALOGENS

Subject Categories : Lasers and Masers
      Inorganic Chemistry
      Organic Chemistry
      Optics

Distribution Statement : APPROVED FOR PUBLIC RELEASE