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Multilevel air gap interconnect structure with photosensitive dielectric

IP.com Disclosure Number: IPCOM000012831D
Original Publication Date: 2003-May-30
Included in the Prior Art Database: 2003-May-30
Document File: 2 page(s) / 67K

Publishing Venue

IBM

Abstract

It is shown how the use of photosensitive dielectric materials can simplify the fabrication of certain air-gap-containg interconnect structures.

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Multilevel air gap interconnect structure with photosensitive dielectric

    Advanced interconnect structures of the future are likely to incorporate air-gap dielectrics, due to the low k value of air (k ~ 1.0). Methods to form multilevel air-gap-containing interconnect structures can be quite complex, relying on multiple etch back, fill, and planarization steps for each level. Disclosed here is a novel approach to making a multilevel air-gap-containing interconnect structure with a combination "air-gap plus solid" via-level dielectric (with the solid dielectric only under the lines) plus a mostly air-gap line-level dielectric. The fabrication method builds up planar via + line level pairs embedded in a dielectric matrix comprising regions of a permanent dielectric and regions of a sacrificial place-holder (SPH) material. When the desired number of line levels have been assembled, the SPH in all the levels is selectively removed through a perforated dielectric bridge layer by an isotropic extraction process (such as ashing or dissolution in a solvent), leaving the permanent dielectric behind. The perforations in the bridge layer are then pinched off by means of an additional dielectric deposition step.

The novel approach disclosed here is based on the use of a photosensitive material that can be changed by exposure to UV light from a permanent low-k dielectric to a selectively removable SPH material. The UV exposure is blanket; the wiring patterns function as a self-aligned mask. The exposure woul...