Motorola Corporation

Freescale Semiconductor,inc.

Al T Koh

Yeong-Jyh Tom Lii

Bich-Yen Nguyen

Robert F Steimle

Kimberly Gay Reid

John M Grant

Marc A Rossow

Jonathan L Cobb

Daniel Thanh-Khac Pham

Anna M Phillips

James P Geren

Ricardo Garcia

Anne Vandooren

Andrea Franke

A method of forming a semiconductor device so as to provide the device inverted isolation trenches with convex sidewalls. Initially, a plurality of composite isolation posts () are formed on a substrate () through successive deposition, lithography, and etching steps. The posts comprise a bottom layer () of silicon dioxide and an overlying etch-stop layer of silicon nitride (). An insulating material () is then deposited over the isolation posts and areas of the substrate. Isolation structures () are established by etching the insulating material to form convex sidewall spacers () at the vertical walls of the isolation posts. Active areas () between spacers are filled with semiconductor material. In an embodiment, a strained cap layer () may be imposed on the active areas. The strained cap layer has a lattice constant that is different from the lattice constant of the semiconductor material.

Inverted isolation formed with spacers

A method for providing gates of transistors with at least two different work functions utilizes a silicidation of two different metals at different times, silicidation for one gate and polysilicon for the other, or silicidation using a single metal with two differently doped silicon structures. Thus the problem associated with performing silicidation of two different metals at the same time is avoided. If the two metals have significantly different silicidation temperatures, the one with the lower temperature silicidation will likely have significantly degraded performance as a result of having to also experience the higher temperature required to achieve silicidation with the other metal.

Method for forming a semiconductor device structure in a semiconductor layer

Growing community of inventors

Austin, TX, United States of America

Al T Koh