DEEP DEPLETION INSULATED GATE FIELD EFFECT TRANSISTOR

摘要

1465244 IGFETs RCA CORPORATION 20 March 1975 [19 April 1974] 11701/75 Heading H1K The channel region 102 of a deep-depletionmode IGFET 78 formed in a thin semi-conductor layer 98 on an insulating substrate 72 comprises an upper layer 103, relatively highly doped (e.g. #1016 atoms/cm3) but less so than the source and drain regions 42, 44 which are of the same conductivity type as the layer 103, and a lower layer 104, also of the same conductivity type as the upper layer 103 but more lightly doped (e.g. # 1013 atoms/cm3-almost intrinsic). In the embodiment the deep-depletion-mode IGFET 78 forms a pair with an enhancement mode IGFET 76 formed identically except that the source and drain regions 82, 84 are of the opposite conductivity type. The substrate 72 is preferably of single crystal (1102) sapphire, Crdoped GaAs or spinel, permitting epitaxial deposition of the Si layer from which the devices 76, 78 are formed. The higher doped upper layers 87, 103 of the channel regions are formed by ion implantation. For n-type devices as shown the gate electrodes 96, 108 are preferably of p+ polycrystalline Si. For p-type devices Al or n+ polycrystalline Si is used.