New in situ electron beam patterning process for GaAs using an electron-cyclotron-resonance plasma-oxidized mask and Cl2 gas etching

A new electron beam (EB) patterning process capable of resistless nanofabrication for GaAs has been developed using enclosed continuous-vacuum processes. These processes are surface oxidation by electron cyclotron resonance (ECR) O2 plasma, oxidized-surface modification by EB irradiation, and subsequent etching by Cl2 gas. The time and oxygen gas pressure required for the oxidation are greatly reduced, compared to other oxidation methods, by using ECR plasma to form an oxide mask for Cl2 gas etching. The plasma-oxidized mask without EB irradiation cannot be removed by Cl2 gas etching even for 4 h at a sample temperature of 100-degrees-C. In spite of its resistance to Cl2 gas etching, the mask can be easily removed by thermal treatment of the sample at about 620-degrees-C in an As atmosphere.