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Proceedings Paper

Improved planarization techniques applied to a low dielectric constant polyimide used in multilevel metal ICs
Author(s): Li-Hsin Chang; Ray Goodner
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Paper Abstract

A low dielectric constant fluorinated polyimide has been employed as the interlevel dielectric in a four-level metal VLSI process. Due to the stringent requirement of a near global planar topography compared with the partial planarizing properties of the polyimide, two advanced approaches were evaluated: (1) a "negative-image" sacrificial photoresist etchback process, and (2) a photoresist image reversal plus dry etch process. Both techniques remove the polyimide from the surface of the metal while leaving polyimide "islands" or "plugs" between the metal features. A second polyimide layer is then applied. The planarity of the finished structure is controlled by the thickness of the initial polyimide layer, the plasma etch process, and the planarizing characteristics of the second or "recoat" polyimide film. The improved global planarity achievable using the advanced techniques were compared to a standard single spin polyimide process using surface profilometer profiles and cross-sectional SEM micrographs. The pros and cons of the two planarization techniques are also discussed.

Paper Details

Date Published: 1 December 1991
PDF: 12 pages
Proc. SPIE 1596, Metallization: Performance and Reliability Issues for VLSI and ULSI, (1 December 1991); doi: 10.1117/12.51009
Show Author Affiliations
Li-Hsin Chang, Motorola Advanced Technology Ctr. (United States)
Ray Goodner, Motorola Advanced Technology Ctr. (United States)

Published in SPIE Proceedings Vol. 1596:
Metallization: Performance and Reliability Issues for VLSI and ULSI
Gennady Sh. Gildenblat; Gary P. Schwartz, Editor(s)

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