US 7,615,425 B2
Open source/drain junction field effect transistor
Joe R. Trogolo, Plano, Tex. (US); Hiroshi Yasuda, Dallas, Tex. (US); Badih El-Kareh, Cedar Park, Tex. (US); and Philipp Steinmann, Richardson, Tex. (US)
Assigned to Texas Instruments Incorporated, Dallas, Tex. (US)
Filed on Aug. 15, 2006, as Appl. No. 11/504,412.
Prior Publication US 2008/0042199 A1, Feb. 21, 2008
This patent is subject to a terminal disclaimer.
Int. Cl. H01L 21/337 (2006.01)
U.S. Cl. 438—186  [257/256] 26 Claims
OG exemplary drawing
 
1. A method of forming a p type junction field effect transistor and an n type junction field effect transistor in a semiconductor substrate, comprising:
forming a first n type buried layer in the substrate;
forming a first p type buried layer in the substrate;
forming a first n type epitaxial layer over the substrate;
forming a second p type buried layer over the first p type buried layer in the first n type epitaxial layer;
forming one or more deep n+ type regions over at least some of the first n type buried layer in the first n type epitaxial layer;
forming a second n type epitaxial layer over the first n type epitaxial layer;
forming a p type surface shield near an upper surface of the second n type epitaxial layer, where the p type surface shield resides over at least some of the second p type buried layer;
forming an n type channel in the second n type epitaxial layer, where the n type channel resides over at least some of the second p type buried layer;
forming a p type back gate extension near a lower surface of the second n type epitaxial layer, where the p type back gate extension resides over at least some of the second p type buried layer and over less than all of the first n type buried layer;
forming an n type surface shield near an upper surface of the second n type epitaxial layer, where the n type surface shield resides over at least some of the first n type buried layer;
forming a p type channel in the second n type epitaxial layer, where the p type channel resides over at least some of the first n type buried layer;
forming one or more isolation areas that isolate the p type junction field effect transistor from the n type junction field effect transistor;
forming one or more n type deep back gate contact regions in the second n type epitaxial layer down to the one or more deep n+ type regions in the p type junction field effect transistor;
forming one or more p type deep back gate contact regions in the second n type epitaxial layer down to the second p type buried layer in the n type junction field effect transistor;
forming a deep p type region in the second n type epitaxial layer down to the second p type buried layer in the p type junction field effect transistor:
forming a layer of silicide block material over the second n type epitaxial layer;
patterning the silicide block material to expose areas of the second n type epitaxial layer where gate, source and drain regions are to be formed;
forming an n type gate region in the p type channel of the p type junction field effect transistor, and n type source and drain regions in the n type channel of the n type junction field effect transistor;
forming p type source and drain regions in the p type channel of the p type junction field effect transistor, and a p type gate region in the n type channel of the n type junction field effect transistor;
siliciding the gate, source and drain regions in the p type channel of the p type junction field effect transistor and the n type channel of the n type junction field effect transistor;
forming a layer of dielectric material over the silicides and second n type epitaxial layer;
forming conductive contacts down through the layer of dielectric material to the silicided gate, source and drain regions in the p type channel of the p type junction field effect transistor and the n type channel of the n type junction field effect transistor; and
forming a field plate over at least one of the conductive contacts extending down to the gate regions of the p type junction field effect transistor and the n type junction field effect transistor, where the field plates also extend over at least some of at least one of the source and drain regions of the p type junction field effect transistor and the source and drain regions of the n type junction field effect transistor.