Chartered Semiconductor Manufacturing Ltd (corporation)

Institute of Microelectronics

Tsun-Lung Alex Cheng

Marokkey Raphael Sajan

Joseph Zhifeng Xie

Leong Tee Koh

Zhu Sui Hua

A new method is provided for the creation of a dual damascene structure. The method of the invention uses a gray tone mask to form dual damascene trenches in one single masking and etch step. The gray tone mask technology allows for a photoresist patterning process after which the photoresist profile can be transferred into the underlying substrate by an etch process. By making the photoresist profile equal to the profile of a dual damascene structure, the dual damascene profile can be created in the surface of a substrate.

One step dual damascene patterning by gray tone mask

Under the first embodiment of the invention, a three layer composite layer of insulation is deposited. The trench is etched into this composite layer of insulation followed by a hard bake. The via etch is performed, completing the formation of the dual damascene profile. The created dual damascene profile is transferred into the underlying substrate; the layer of photoresist is removed. Under the second embodiment of the invention, a two layer composite layer of insulation is deposited over a semiconductor surface. The trench is etched into this composite layer of insulation. A layer of positive photoresist is deposited over the second layer of cross-linked negative resist and masked for the via etch. The via etch is performed, the created dual damascene profile is transferred into the underlying substrate. The removal of the layers of patterned photoresist completes the formation of the dual damascene structure.

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Singapore, Singapore

Tsun-Lung Alex Cheng