Structure and method for FinFET device with buried sige oxide

摘要

The present disclosure provides a semiconductor device that includes a substrate of a first semiconductor material; a fin feature having a first portion, a second portion and a third portion stacked on the substrate; an isolation feature formed on the substrate and disposed on sides of the fin feature; semiconductor oxide features including a second semiconductor material, disposed on recessed sidewalls of the second portion, defining dented voids overlying the semiconductor oxide features and underlying the third portion; and a gate stack disposed on the fin feature and the isolation feature. The gate stack includes a gate dielectric layer extended into and filling in the dented voids. The first and third portions include the first semiconductor material having a first lattice constant. The second portion includes the second semiconductor material having a second lattice constant different from the first lattice constant.

主权项

1. A semiconductor device comprising:
a substrate of a first semiconductor material having a first lattice constant; a fin feature formed on the substrate, wherein the fin feature includes a first portion of the first semiconductor material disposed over the substrate; a second portion of a second semiconductor material disposed over the first portion, wherein the second semiconductor material has a second lattice constant different from the first lattice constant; and a third portion of the first semiconductor material disposed over the second portion; an isolation feature formed on the substrate and disposed on sides of the fin feature, wherein the second portion includes recessed sidewalls; semiconductor oxide features including the second semiconductor material, disposed on the recessed sidewalls of the second portion, defining dented voids overlying the semiconductor oxide features and underlying the third portion of the fin feature, wherein the isolation feature includes an edge portion contacting a sidewall of the semiconductor oxide features, wherein the edge portion of the isolation feature has a top surface below a top surface of the second portion; and a gate stack disposed on the fin feature and the isolation feature, wherein the gate stack includes a gate dielectric layer extended into and filling in the dented voids, thereby forming side dielectric tips in the dented voids.