Taiwan Semiconductor Manufacturing Comp. Ltd.

Chih-Shen Hung

Cheng-Hao Huang

Wen-Hsiang Tang

Yi-Fei Wang

A method of high aspect ratio etching (HARE) of metal layers in quarter micron technology is disclosed. High aspect ratio patterns are encountered because of the shrinking lateral dimensions over the constant remaining thickness of the features of ultra large scaled integrated chips. HARE is accomplished by employing a tungsten W-hardmask with a high selectivity of 10:1 with respect to the immediately underlying aluminum-copper metal layer. In order to protect the lithographic integrity, overlying organic BARC is used to prevent reflections from the W-hardmask as well as from the underlying metal layer. The lithographic resolution is further improved by using a thin photoresist layer in combination with the high selectivity hardmask. In this manner, the tradeoff that normally has to be made between a high resolution process and a reliable metal etch is circumvented.

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Hsin-Chu, Taiwan

Chih-Shen Hung