SEMICONDUCTOR SHIFT REGISTER USING POLYCRYSTALLINE SILICON

摘要

1336301 Semi-conductor devices INTERNATIONAL BUSINESS MACHINES CORP 17 Oct 1972 [3 Nov 1971] 47774/72 Heading H1K A capacitor structure forming part of a semiconductor device comprises a semi-conductor body, an insulating layer on a sufrace of the body, a layer of doped polycrystalline semiconductor material overlying the insulating layer, a second insulating layer on the layer of polycrystalline material and a layer of conductive material in ohmic contact with the semi-conductor body overlying the polycrystalline layer and separated therefrom by the second insulating layer, the semi-conductor body and conductive layer forming one electrode of the capacitor, the polycrystalline layer, the second electrode and the insulating layers the dielectric. As shown the device is a bucket brigade shift register wherein such capacitors are connected between the collector and base of an array of switching bipolar transistors (Figs. 1 and 2, not shown). The transistors, comprising collector 40, collector contact region 42, base 44 and emitter 46, are formed in epitaxial layer 36 on monocrystalline silicon substrate 34 after sub-collector diffusion 38 has been formed. The transistors are separated by isolation diffusions 48. Layer 36 is covered by insulating layer 50 comprising thermal SiO 2 or SiO 2 /Si 3 N 4 with apertures for emitter, base and collector contacts 16, 18, 14. Layer 52 of doped polycrystalline silicon is insulated from overlying conductive layer by thermal SiO 2 layer 54. The capacitance of the device is between extension (58) of collector terminal 14 (Fig. 3, not shown) and polycrystalline layer 52 and between. collector region 40 and layer 52, one layer being in electrical contact with base terminal 18 through opening (56) (Fig. 3, not shown) in layer 54. Preferably the base terminals extend alternatively in opposite directions to contactone of a pair of clock lines (Fig. 3, not shown), best illustrated by the prior art arrangement (Fig. 1, not shown). The various metal layers may be deposited aluminium. In an alternative construction the device uses field effect transistors (Figs. 4, 5, not shown).