Novellus Systems Incorporated

Guangquan Lu

Sean C Chang

Bhadri N Varadarajan

Kevin J Ilcisin

Victor Y Lu

James Samuel Sims

Maxim Kelman

Krishnan Shrinivasan

Feng Wang

David Mordo

Michael Carris

Mandar Pandit

A highly tensile dielectric layer is generated on a heat sensitive substrate while not exceeding thermal budget constraints. Ultraviolet (UV) irradiation is used to produce highly tensile films to be used, for example, in strained NMOS transistor architectures. UV curing of as-deposited PECVD silicon nitride films, for example, has been shown to produce films with stresses of at least 1.65 E10 dynes/cm. Other dielectric capping layer film materials show similar results. In transistor implementations, the stress from a source/drain region capping layer composed of such a film is uniaxially transferred to the NMOS channel through the source-drain regions to create tensile strain in the NMOS channel.

Tensile dielectric films using UV curing

The present invention addresses provides improved methods of preparing a low-k dielectric material on a substrate. The methods involve multi-step ultraviolet curing processes in which UV intensity, wafer substrate temperature and other conditions may be independently modulated at each step. In certain embodiments, a film containing a structure former and a porogen is exposed to UV radiation in a first step to facilitate removal of the porogen and create a porous dielectric film. In a second step, the film is exposed to UV radiation to increase crosslinking within the porous film. In certain embodiments, the curing takes place in a multi-station UV chamber wherein UV intensity and substrate temperature may be independently controlled at each station.

Method for reducing stress in porous dielectric films

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Fremont, CA, United States of America

Guangquan Lu