Simplified ohmic and Schottky contact formation for field effecttransistors using the single layer integrated metal field effecttransistor (SLIMFET) process |
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Authors: | DeSalvo GC Quach TK Bozada CA Dettmer RW Nakano K Gillespie JK Via GD Ebel JL Havasy CK |
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Affiliation: | Wright Lab., Wright-Patterson AFB, OH; |
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Abstract: | A new III-V semiconductor device fabrication process for GaAs-based field effect transistors (FET) is presented which uses a single lithographic process and metal deposition step to form both the ohmic drain/source contacts and the Schottky gate contact concurrently. This single layer integrated metal FET (SLIMFET) process simplifies the fabrication process by eliminating an additional lithographic step for gate definition, a separate gate metallization step, and thermal annealing for ohmic contact formation. The SLIMFET process requires a FET structure which incorporates a compositionally graded InxGa1-xAs cap layer to form low resistance, nonalloyed ohmic contacts using standard Schottky metals. The SLIMFET process also uses a Si3N4 mask to provide selective removal of the InGaAs ohmic layers from the gate region prior to metallization without requiring an additional lithographic step. GaAs MESFET devices were fabricated using this new SLIMFET process which achieved DC and RF performance comparable to GaAs MESFET's fabricated by conventional methods |
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