Integrated Circuits Incorporating Thin-Film Active and Passive Elements P. K. WEIlfER, FELLOW, IEEE, H. BORmV, SENIOR MEMBER, IEEE,

The most spectacular achievements in integrated electronics undoubtedly fall in the category of Devices and Structures. The realization of useful circuit functions through combination of the new materials technology, new process technology, and the exploration of functional circuit needs above the discrete device level represents the first departure from conventional electronics using solid-state components. The use of the word integrated as the modifier for this new form of electronics signifies the combination of the previously separate disciplines of materials, devices, and circuits into a single discipline; not, as is sometimes erroneously assumed, just the combination of previously discrete components into a single function entity. Of the many problems facing the integrated circuit technologist, none is more intriguing or elusive than the practical realization of active as well as passive circuit elements in thin-film form. The following invited paper by Dr. P. I(. LYeimer, and his associates, describes a significant approach to the subject.-The Editors Summary-The thin-film field-effect transistor (TFT) provides the active element for complex integrated circuits deposited upon an insulating substrate. N-type transistors are obtained with evaporated layers of cadmium sulfide or selenide and *type transistors with evaporated tellurium. Switching speeds of less than 4 nsec and gainbandwidth products of greater than 30 Mc are observed with polycrystalline films of cadmium sulfide. Oscillations at frequencies up to 74 Mc have been noted. Significant improvements in the life and stability of the coplanar-electrode TFT have been obtained by encapsulation. A 30-stage completely integrated thin-film scan generator incorp+ rating 60 TFT’s, 30 diodes, 60 resistors and 30 capacitors has been designed. The novel circuit, whose operating characteristics resemble those of a shift register, is deposited by evaporation using movable metal masks controlled from outside the vacuum system. In one unit 28 consecutive stages were operated for nearly 700 hours. Laboratory models of the scan generator are being used to drive the address strips in experimental solid-state image-sensor panels.