Formation and characterization of shallow junctions by through-film ion implantation in GaAs

Abstract

Plasma-enhanced chemical vapor deposited Si 3N 4 thin film with a thickness of 140 nm was used as a mask to form shallow junctions by Si ion implantation. The implantation energy ranged from 60 to 120 keV and the doses were 4×10 14 cm −2 and 1×10 15 cm −2. Rapid thermal annealing was carried out at temperatures ranging from 850 up to 1050°C for 5 s. The active layers were characterized by HL5900 Stripping Hall System. Junctions as shallow as 30 to 200 nm were formed with electron concentrations of about 10 18 cm −3. It was found that the electron concentrations at the depth close to the surface were anomalously lowered and the results obtained by TRIM'91 program simulation. By coimplantation of P ions, the activation efficiency of silicon increased greatly. The electron concentration profile configuration fits well the simulated one. An electron concentration as high as about 10 19 cm −3 was obtained near the surface.