No abstract

A novel multilevel interconnect scheme has been developed as part of an advanced submicron CMOS process technology. A salient feature of this interconnect scheme is the use of metal pillars for vertical connections between the devices on the substrate and the first level of metallization, as well as between successive levels of metallization, in place of the conventional etched contacts and vias. The pillar and conductor levels, with feature dimensions below 1 μm, were defined using contrast enhancement lithography and reactive ion etching. The application of these techniques to the definition of small and sparse photoresist features on an uneven metallic substrate and to the subsequent pattern transfer to the underlying metal films is described. The issues of surface topography and reflectivity, small‐area photoresist coverage, and dimension and profile control in the patterning of submicron features are addressed.

A multilevel metallization system, which results in smooth topography and high packing density by overcoming many of the limitations of the conventional approach, has been developed. In this scheme metallic pillars are used for interlevel wiring, instead of traditional contacts and vias. Refractory metal layers are employed at all levels as an etch stop/ diffusion barrier with a self-aligned metal silicide used to insure low contact resistance between conductor (aluminum) and silicon substrate. Planarized SiO2 is used as the dielectric at each level in which planarization of the dielehtric and exposure of the underlying metallization are achieved by the etchback technique using sacrificial photoresist films. This interconnection scheme can be extended to any number of levels of interconnection and may be readily scaled for use in submicron ULSI technologies.

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A cutaneous horn (corn cutaneum) is a dense, hyperkeratotic conical projection of skin arising from an unusual cohesiveness of keratinized material. Cutaneous horns most frequently occur in sites that are exposed to actinic radiation or burns. Forearm, cartilaginous portion of the ear, legs, and hands may also be affected. Cutaneous horns can occur in sun protected areas. Histologic confirmation is necessary to rule out malignant changes. No clinical features reliably distinguish between benign and malignant lesions. This is a case report of a cutaneous horn over inguinal region.