Abstract

Pulsed laser etching of copper using chlorine has been demonstrated and investigated (1-3). Chlorine, however, strongly corrodes copper even in the absence of light. To avoid this problem, we have examined UV photoetching of copper using the vapor of two room temperature liquids, CF₂Br₂ and CCl₄. Both species are inert towards copper in the dark, but will undergo gas-phase photolysis with near unit quantum efficiency to produce Br or Cl atoms. At 248 nm, the gas-phase absorption of CF₂Br₂ is some 3 orders larger than CCl₄ Yet surprisingly, the 248 nm etch rate is similar for both over the range 1-10 torr. At 351 nm, where the gas-phase absorption for both species becomes vanishingly small, CCI₄ is observed to etch copper with the same rate as at 248 nm, while CF₂Br₂ does not cause etching. These results suggest that gas-phase photolysis of CF₂Br₂, but not CCI₄, is important in initiating copper etching.

© 1989 Optical Society of America