Jpn. J. Appl. Phys. 47 (2008) pp. 3412-3417  |Next Article|  |Table of Contents|
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Development of Developer-Soluble Gap Fill Materials for Planarization in Via-First Dual Damascene Process

Satoshi Takei, Yasushi Sakaida, Kazuhisa Ishii, and Tetsuya Shinjo

(Received November 16, 2007; accepted January 24, 2008; published online May 16, 2008)

Gap fill materials and planar-type bottom antireflective coating are needed for patterning metal trenches in the via-first dual damascene process. We have already reported on thermal cross-link gap fill materials and bottom antireflective coating as planarizing layers under a resist that can be spin-coated and etched faster than resists. In this study, developer-soluble gap fill materials were optimized in order to obtain excellent planarization, simplify the process, and increase wafer throughput. The developer-soluble gap fill materials using poly(4-hydroxystyrene) derivatives developed by an approach of the via-first dual damascene process was obtained by optimizing the concentration of the phenol group with solubility in the alkaline developer (0.26 N tetramethylammonium hydroxide, TMAH) and by thermal cross-link reaction. In addition to a superior via-filling performance, developer-soluble gap fill materials using poly(4-hydroxystyrene) derivatives showed a wide process window of prebake temperature, the controllable dissolution rate for the etch-back process, and a good CF₄ etch rate of 1.4 times higher than that of a resist for etching the substrate. These results were attributed to the polymer structures of poly(4-hydroxystyrene) derivatives. Both dry plasma cleaning and wet developer cleaning can be used to remove residual gap fill materials after processing. This novel approach using developer-soluble gap fill materials as a new type of sacrificial material in an advanced lithography process makes this solution convenient for planarizing surfaces and is economically favorable owing to high throughput.

URL: http://jjap.jsap.jp/link?JJAP/47/3412/
DOI: 10.1143/JJAP.47.3412
KEYWORDS:lithography, gap fill materials, planarization, etch rate, dual damascene

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