Applied Materials, Inc.

Ganming Zhao

Jeffrey D Chinn

Padmapani Nallan

Jeff Chinn

Thalia Kong

The present disclosure pertains to our discovery that a particular sequence of processing steps will lead to the formation of a rounded top corner on a trench formed in a semiconductor substrate. In general, the method of the invention includes the following steps: (a) providing a film stack comprising the following layers, from the upper surface of the film stack toward the underlying substrate, (i) a first layer of patterned material which is resistant to a wet etch solution used to etch an underlying second layer and which is resistant to dry etch components used to etch the semiconductor substrate, and (ii) a second layer of material which can be preferentially etched using a wet etch solution, wherein the second layer of material is deposited directly on top of the semiconductor substrate; (b) wet etching the second layer by immersing the film stack in a wet etch solution for a period of time sufficient to form an undercut beneath the first layer and to expose the underlying semiconductor substrate; and (c) isotropically dry etching the exposed semiconductor substrate so as to form a trench in the semiconductor substrate. The present invention provides a method for obtaining a rounded top trench corner while at the same time retaining excellent control of the critical dimensions of the trench. The method of the invention, which is useful in both shallow trench and vertical trench applications, provides a rounded top trench corner having a radius within the range of about 150 &angst; to about 500 &angst;, most preferably, within the range of about 200 &angst; to about 350 &angst;.

Method of obtaining a rounded top trench corner for semiconductor trench etch applications

An etchant composition for etching straight walled, tapered trenches in silicon comprising chlorine, nitrogen and a mixture of helium and oxygen. The resultant trenches can be readily filled with a dielectric material without the formation of voids. The etchant of the invention is less corrosive, and thus provides increased chamber life and reduced costs over hydrogen bromide-containing etchants.

Growing community of inventors

Fukushima, Japan

Ganming Zhao