Process enhancement using molybdenum plugs in fabricating integrated circuits

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS The use of a moly plug in accordance with the invention allows aluminum to make contact through a thermally stable barrier with other interconnects, diffusions or gates as well as thin film resistors.
The process permits the simultaneous formation of another level of interconnect using the moly as an interconnect and also as a barrier plug.
Further, the moly plug process allows the use of diffusion as an interconnect by allowing the contact of moly as a strap.
Thus, aluminum to moly to diffusion strap can be easily created.
Additionally, two or more levels of interconnects can be contacted with diffusions using the moly as a barrier between the interconnect (aluminum, polysilicon, silicide poly or refractory metals) and the diffusion.
By using the moly plug process as a strap between various interconnect levels, two dissimilar interconnects that might metallurgically interact with each other can be strapped and electrically connected to each other using the moly plug process.
Referring now to the drawing, FIG.
1 is a section view of a portion of an integrated circuit illustrating the general process scheme for forming multi-level interconnects and contacts between various circuit elements.
In this embodiment a silicon substrate 10 has a diffused region 12 in a surface thereof.
Formed on the surface is a silicon oxide layer 14 and silicon nitride layers 16,18.
A thick oxide layer 20 is formed over the nitride layers, and formed on the oxide layer 20 is a thin film resistor 22 and a plurality of aluminum contacts 24, 26, 28, and 30.
Nitride and oxide layers 32 and 34, respectively, are formed on the top of the structure.
In section one of the structure a moly one layer 36 and a moly two layer 38 are separated by thin nitride layer to function as a capacitor.
In section two of the circuit, the moly one and moly two layers form a plug separating the aluminum contact 26 from the diffused region 12.
In section three of the circuit, the moly one layer separates the contacts 28 and 30 from opposite ends of the thin film resistor 22