Another Step in Developing a Single Wafer Integrated Process: Rapid Thermal Low Pressure Metalorganic Chemical Vapor Deposition of Local Diffused W(Zn) Contacts

A selective deposition of W(Zn) metallization, for formation of diffused ohmic contacts onto InP-based material was realized by means of rapid thermal, low pressure metalorganic chemical vapor deposition (RT-LPMOCVD). The W(Zn) layers were deposited using a reactive gas mixture that contained diethylzinc (DEZn), WF 6 , H 2 and Ar, at temperatures of 450 to 550°C and pressures in the range of 1–5 torr. Uniform andcontinuous layers of W(Zn), 30 to 120 nm thick, were obtained. These layers contained Zn at concentrations higher than 1×l0 18 cm −3 , which was subsequentially in-diffused into the underlying semiconductor layer to form highly doped semiconductor layers as thick as 0.2μm. As a result, the specific contact resistance of the W(Zn)/ In 0.53 Ga 0.47 As contact was reduced to minimum value of 5×l0 −6 Ω·cm 2 . The W(Zn) film were found to be mechanically stable with a small compressive stress of 5.10 −8 dyne. cm −2 , and dry etch rates of up to 90 nmmin.