method for manufacturing a, an isolated stuurelektrode veldeffecttransistor provided the verrijkingstype and veldeffecttransistor manufactured with this method.

摘要

1,248,580. IGFETs. GENERAL ELECTRIC CO. 7 Oct., 1968 [13 Oct., 1967], No. 47482/68. Heading H1K. In making an IGFET the gate electrode is used to mask the semi-conductor during formation of the source and drain regions by diffusion. In one embodiment one or more pairs of complementary IGFETs are formed in an N-type silicon wafer 60 (Fig. 6) using common processing steps. First a genetic oxide layer 62 is formed on one face by heating in oxygen followed by annealing in helium. Molybdenum (or tungsten) 63 is then deposited overall by a glow discharge process and selectively removed from the sites of the sources and drains. A pure silica layer 75 is deposited overall and thinned by etching over the N channel IGFET sites prior to deposition of a boron-doped silica layer 76. The masking effect of the various oxide and molybdenum layers is such that in a subsequent heating boron diffuses inward to produce a continuous P-type base layer 82 at the site of each N channel device and spaced P-type source and drain inclusions 78, 79 where the oxide was not thinned. After removal of the boron doped oxide, phosphorus doped oxide 83 is applied over the N channel device sites by overall deposition followed by selective etching, and then diffused in. The molybdenum masks this diffusion to provide spaced N-type source and drain inclusions 86, 87 in each P-type base. Contacts and any desired interconnections are finally provided by suitably aperturing the insulating layers, depositing aluminium overall and then form etching. One or more N channel IGFETs only may be made on an N-type body by a simplified version of the above process. In this the boron doped film may be deposited directly: on the patterned molybdenum and the pure oxide either superposed on it before or after boron diffusion or dispensed with altogether. To form P channel devices on a P-type wafer, after forming the genetic oxide layer and molybdenum pattern phosphorus doped oxide is deposited and diffused in to form the sources and drains. A deposited layer of pure oxide may be provided between it and the pattern or on top of it. In a further alternative the pure oxide is deposited prior to patterning the molybdenum layer. In all the above processes the oxide layers are deposited by pyrolysis of ethyl orthosilicate alone or mixed with triethyl phosphate or borate where doping is required. Patterning of the various layers for forming masks, apertures, and contacts is effected by photoresist and etching steps using ferricyanide, a mixture of orthophosphoric, acetic and nitric acids; and hydrofluoric acid to remove molybdenum, aluminium and oxides respectively. Concentric and linear source and drain configurations are described. Where a number of identical devices are made on a common wafer it may subsequently be cut up and individual devices ohmically attached to headers using gold-indium alloy or donor-doped gold according to whether the wafer is P or N type.