Abstract:
PROBLEM TO BE SOLVED: To provide a gate structure for MOSFETs for application of the CMOS technology, etc., which is durable against high temperature processes such as junction activation, etc., and reduces the gate propagation delay. SOLUTION: The gate structure 10 has an insulation layer 14 on a semiconductor substrate 12, and a polysilicon gate electrode 16 on the insulation layer 14. The gate structure 10 comprises a diffused barrier layer 20 having semi- insulative characteristics on the gate electrode 16, and a gate conductor 18 on the barrier layer 20. The conductor 18 is electrically contacted to the gate electrode 16. The constitution and the thickness of the barrier layer 20 are adjusted so as to effectively block the diffusion and the mixing between the gate conductor 18 and the gate electrode 16, but realize a capacitive coupling and/or a leak current not so increasing the gate propagation delayer of the gate surface 10.
Abstract:
A method of forming relatively thin uniform insulating collar in the storage trench of a storage trench DRAM cell. A DRAM trench is first formed in a silicon substrate. Then, a nitride liner (81) is deposited on the silicon trench walls. The nitride liner may be deposited directly on the silicon walls or on an underlying oxide layer (79). A layer of amorphous silicon (83) is then deposited over the nitride liner. A silicon nitride layer is deposited on the oxidized surface of the amorphous silicon. A resist (83) is formed in the lower portion of the trench, and the exposed silicon nitride layer on top of the amorphous silicon is removed, leaving the upper portion of the amorphous silicon layer exposed. The upper portion of the layer of amorphous silicon is then oxidized so as to form a relatively thin, uniform collar (89) along the entire circumference of the trench. The nitride liner underlying the amorphous silicon layer enhances the thickness uniformity of the amorphous silicon layer and thereby the uniformity of the resulting oxide collar. The nitride liner also acts to limit lateral oxidation of the silicon trench walls during oxidation of the amorphous silicon layer. The nitride liner underlying the collar is also effective in cell operation to control the cell charge at the collar-substrate interface.
Abstract:
A conductive structure in an integrated circuit ( 12 ), and a method of forming the structure, is provided that includes a polysilicon layer ( 30 ), a thin layer containing titanium over the polysilicon, a tungsten nitride layer ( 34 ) over the titanium-containing layer and a tungsten layer over the tungsten nitride layer. The structure also includes a silicon nitride interfacial region ( 38 ) between the polysilicon layer and the titanium-containing layer. The structure withstands high-temperature processing without substantial formation of metal silicides in the polysilicon layer ( 30 ) and the tungsten layer ( 32 ), and provides low interface resistance between the tungsten layer and the polysilicon layer.