CMOS structures and methods for improving yield
View Patent ↗A simple, effective and economical method to improved the yield of CMOS devices using contact etching stopper liner, including, single neutral stressed liner, single stressed liner and dual stress liner (DSL), technology is provided. In order to improve the chip yield, the present invention provides a method in which a sputter etching process is employed to smooth/flatten (i.e., thin) the top surface of the contact etch stopper liners. When DSL technology is used, the inventive sputter etching process is used to reduce the complexity caused by DSL boundaries to smooth/flatten top surface of the DSL, which results in significant yield increase. The present invention also provides a semiconductor structure including at least one etched liner.
1. A semiconductor structure comprising:
a first transistor of a first polarity laterally separated from a second transistor of a second polarity different than the first polarity over a semiconductor substrate; and
at least one stressed layer over said first and second transistors, wherein said at least one stressed layer comprises a first stressed layer portion having a first stress over said first transistor and a second stressed layer portion of a second stress that differs from said first stress over said second transistor, wherein said first and second stressed layer portions abut and overlap each other over an isolation region and said second stressed layer portion that overlaps said first stressed layer portion has tapered sidewalls that form an inverted V-shape having an apex over said isolation region, and wherein an etch stop material portion is located only over said isolation region and between a portion of said first stressed layer portion and said second layer portion and wherein said at least one stressed layer over the first and second transistors has tapered surface sidewalls over the first transistor and second transistor that meet each other at a pointed tip forming an inverted V-shaped stress layer over each of the first transistor and the second transistor,
wherein an apex of the pointed tip of each of said inverted V-shaped stress layer is present between opposing sidewalls of the gate electrode of each of the first and second transistors, and
wherein:
a first thickness of the at least one stressed layer is defined as the thickness of a first portion of the at least one stressed layer between the opposing sidewalls of the gate electrode of each of the first and second transistors,
a second thickness of the at least one stressed layer is defined as the thickness of a second portion of the at least one stressed layer different from the first portion, and
the first thickness is less than the second thickness.
2. The semiconductor structure of claim 1 wherein said at least one stressed layer over one of said first transistor and second transistors has a compressive stress.
3. The semiconductor structure of claim 2 wherein said at least one stressed layer over one of said first transistor and second transistors has a tensile stress.
4. The semiconductor structure of claim 1 further comprising a stressed neutral layer atop the at least one stressed layer.
5. The semiconductor structure of claim 1 further comprising an interlevel dielectric material having contact vias located therein atop said semiconductor substrate and said at least one stressed layer.
6. A semiconductor structure comprising:
a first transistor of a first polarity laterally separated from a second transistor of a second polarity different from the first polarity over a semiconductor substrate, wherein at least one dummy gate is located on a surface of a trench isolation region in said substrate between said first and second transistors;
a first stressed layer having a first stress located over the first transistor; and
a second stressed layer having a second stress different from said first stress over the second transistor, said second stressed layer over said second transistor has tapered surface sidewalls that meet each other forming a first inverted V-shaped second stress layer portion, wherein said first inverted V-shaped second stress layer portion has a first pointed tip located directly over a gate electrode of the second transistor and said first pointed tip of said first inverted V-shaped second stress layer does not extend beyond a sidewall the gate electrode of second transistor, and wherein said first stressed layer and said second stressed layer overlap each other in an area over the dummy gate, wherein said second stressed layer in said overlap area has tapered surface sidewalls that meet each other forming a second inverted V-shaped second stress layer portion, wherein said second inverted V-shaped second stress layer portion has a second pointed tip having an apex that provides the single highest point of the second pointed tip that is located over the dummy gate and is between opposing sidewalls of said dummy gate,
wherein:
a first thickness of the second stressed layer is defined as the thickness of a first portion of the second stressed layer between the opposing sidewalls of the gate electrode of the second transistor,
a second thickness of the second stressed layer is defined as the thickness of a second portion of the second stressed layer different from the first portion, and
the first thickness is less than the second thickness.
7. The semiconductor structure of claim 6 further comprising a stressed neutral layer atop the first and second stressed layers.
8. The semiconductor structure of claim 6 further comprising an interlevel dielectric material having contact vias located therein atop the semiconductor substrate and the first and second stressed layers.