Patrick Rabinzohn

Contact Lithography Modelling Using Statistical Experimental Designs

A Statistical Experimental Design Methodology has been applied to contact lithography modelling for GaAs technology. The AZ 4000 resists have been used with three thicknesses 1, 2 and 3 µm. A standard process with UV4 and UV3 exposures and a post exposure bake process with UV4 exposure have been modelled. Two optimisations of the UV4 process leading to vertical profiles and an optimization of the PEB process leading to a lift-off profile are presented.

The new two-dimensional electron gas base HBT (2DEG-HBT): two-dimensional numerical simulation

The bipolar/FET characteristics of the 2DEG-HBT are analyzed extensively by a two-dimensional numerical simulator based on a drift-diffusion model. For bipolar operations at high collector current densities, it is confirmed that the cutoff frequency f/sub T/ is determined mainly by the collector transit time of holes and by the charging time of the extrinsic base-collector capacitance C/sub bc//sup EXT/. The charging times of the emitter and base regions and the base transit time are shown to be negligible. A high cutoff frequency F/sub T/ (88 GHz) and current gain h/sub FE/

On the Determination of the Specific Contact Resistance of Alloyed Contacts to n-GaAs

The popular distributed model for metal-semiconductor ohmic contacts is extended to take into account the nonplanar nature of alloyed contacts. AuGe/Ni ohmic contacts are fabricated on n-GaAs epitaxial layers (3×1018 cm-3, 160 nm) with an undoped cap layer of varied thickness. Thus the specific contact resistance and the so-called alloyed depth are determined from the measured contact resistances. Typical values are, respectively, 10-7 Ωcm2 and 250 nm.

High quality plasma planarization: methodology and application to maskless selective interconnection

Abstract Reliable and tunable plasma planarization processes result from an extensive modelling of the sacrificial layer planarization efficiency as well as the back etching uniformity and selectivity. In addition a new maskless selective interconnect technique with unequaled packing density potential is demonstrated.