Silicon-on-sapphire mesa transistor having doped edges
AssigneeRCA Corporation
InventorWilliam Edward Ham
Life of this patent
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Abstract
Instabilities in the leakage current and threshold voltage of a field effect transistor on an insulator substrate, at both room temperature and after operation at relatively high temperatures (150.degree. C), are substantially reduced by selectively doping edge regions adjacent the transverse side surfaces of the channel region of the field effect transistor, wherein the breakdown voltage of the channel-to-drain junction is substantially increased. Atoms are placed in these edge regions to provide therein a carrier concentration of at least 5 .times. 10.sup.16 atoms-cm.sup.-3 of the opposite conductivity type to that of the source and drain regions. The doped edge region extends partly across said channel region and extends fully across the side surface at the end of the source region.
Claims9
In a semiconductor device comprising:
- a substrate of electrically insulating material,
- a mesa of single crystal semiconductor material on said substrate,
- said mesa having transverse surfaces extending transversely from said substrate,
- means defining a field effect transistor having source and drain regions and a channel region, said channel region extending between said source and drain regions and between two of said transverse surfaces, and doped edge regions, in said channel region adjacent said two transverse surfaces of said channel region, having more conductivity modifiers than in the remainder of said channel region,
- said conductivity modifiers being of the opposite conductivity type as that of said source and drain regions,
- the improvement comprising said doped edge regions being extended only partly across said channel region adjacent a portion of the two transverse surfaces of the channel region and further comprising the doped edge region being extended adjacent the side surfaces only in said source region, whereby the breakdown voltage at any junction including said channel region at a side surface is substantially the same as the breakdown voltage of said field effect transistor.
Dependencies are inferred from the claim text.