Process technology for InGaAs/InAlAs modulation doped field effect transistors in InP substrates
- Institut fur Angewandte Festkoerperphysik, Freirburg (Germany); and others
We present a process for fabricating lattice-matched InGaAs/InAlAs modulation doped field effect transistors (MODFETs)on InP wafers including molecular beam epitaxial growth of a high electron mobility transistor structure consisting of In{sub 0.53}Ga{sub 0.47}As and In{sub 0.52}Al{sub 0.48}As layers, and a electron-beam lithography for gate definition. For selective gate recessing we investigates both wet and dry etch processes. Viable procedures have been found with a citric acid: H{sub 2}O{sub 2}: H{sub 2}O wet etching solution and with an HBr/Ar gas mixture for reactive ion etching (RIE). The selective obtained for InGaAs with respect to InAlAs were 14:1 for the wet etchant and 6.7:1 for RIE. Another crucial process step is the MODFET isolation. Earlier work by other groups has shown that implant isolation is difficult on InGaAs. Therefore, we studied both oxygen ion implantation as well as wet-chemical mesa etching for device isolation on the same wafer. Although the isolation sheet resistance achieved with ion implantation is inferior to that obtained in a mesa process, we found similiar MODFET performance for both approaches. For devices with a 0.3-{mu}m gate length and 1.3-{mu}m source-drain distance, a transconductance of more than 600 mS/mm and threshold voltages of -1.3 and -0.6 V for wet and dry recessed transistors, respectively, were obtained. Wafer mapping measurements showed that MODFET data are uniform over an entire 2-in. wafer also from wafer-to-wafer within a batch. 14 refs., 3 figs., 2 tabs.
- OSTI ID:
- 263458
- Journal Information:
- Journal of Vacuum Science and Technology. B, Microelectronics Processing and Phenomena, Journal Name: Journal of Vacuum Science and Technology. B, Microelectronics Processing and Phenomena Journal Issue: 6 Vol. 12; ISSN JVTBD9; ISSN 0734-211X
- Country of Publication:
- United States
- Language:
- English
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