PATENT COVER GRAPHIC |
United States Patent 3,489,622 January 13, 1970 Method Of Making High Frequency Transistors Fred Barson Vir A. Dhaka Filed May 18, 1967 |
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Abstract of the DisclosureA method of making transistors useful for high frequency applications by forming on the surface of a semiconductor substrate of a first conductivity type a silicon dioxide layer doped with a conductivity determining impurity of opposite type. The doped layer covers only the portions of the surface corresponding to the selected extrinsic base area of the transistor; the intermediate portion of the surface corresponding to the selected intrinsic base area is left uncovered. The extrinsic base is formed by diffusion from the doped layer and the intrinsic base and emitter are formed by diffusion through the intermediate uncovered area. |
Figure descriptions: cover graphic |
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Citations [54]:3,312,881 04/1967 Yu 3,389,023 06/1968 |
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