Thermal dry-etching of nickel using oxygen and 1,1,1,5,5,5 - hexafluoro-2,4-pentanedione (Hhfac)

A thermal dry-etching process of nickel (Ni) was studied using 1,1,1,5,5,5-hexafluoro-2,4-pentanedione (Hhfac). This process realizes isotropic etching of nickel at high rates without using halogens such as chlorine or fluorine. There are two main reactions in the process; (i) oxidation of nickel by oxygen to form nickel oxide and (ii) subsequent removal of nickel oxide by reaction with Hhfac. Nickel was etched at temperatures as low as 250°C and at rates of up to 500 nm min^-1 at 325 °C by simultaneous flow of Hhfac with oxygen under an appropriate flow ratio over a heated substrate. Hhfac etching did not proceed in absence of oxidizer with the metal nickel surface and exposure to the fully oxidized nickel surface. The etching rate increased with substrate temperature and chamber pressure over the range of the parameters studied. This process is expected to apply for removal of the depositions inside the chemical vapor deposition reactor and selective etching of the metal film on the micro devices.