Semiconductor structure having an abrupt doping profile
AssigneeInternational Business Machines Corporation
InventorsFrank Cardone, Jack Oon Chu, Khalid EzzEldin Ismail
Life of this patent
Estimating the term…
Abstract
A structure and method of forming an abrupt doping profile is described incorporating a substrate, a first epitaxial layer of Ge less than the critical thickness having a P or As concentration greater than 5×1019 atoms/cc, and a second epitaxial layer having a change in concentration in its first 40 Å from the first layer of greater than 1×1019 P atoms/cc. Alternatively, a layer of SiGe having a Ge content greater than 0.5 may be selectively amorphized and recrystalized with respect to other layers in a layered structure. The invention overcomes the problem of forming abrupt phosphorus profiles in Si and SiGe layers or films in semiconductor structures such as CMOS, MODFET'S, and HBT's.
Claims9
A structure having an abrupt doping profile comprising:
- a single crystal semiconductor substrate having an upper surface,
- a first epitaxial layer of Ge over said upper surface,
- said first epitaxial layer having a thickness in the range from about 0.5 nm to about 2 nm, said first epitaxial layer having a concentration of dopant greater than 5×1019 atoms/cc, said dopant selected from the group consisting of phosphorus and arsenic, and
- a second epitaxial layer of a semiconductor material over said first epitaxial layer.
A field effect transistor comprising:
- a single crystal substrate having a source region and a drain region with a channel therebetween and a gate electrode above said channel to control charge in said channel, and
- a first layer of Ge from about 0.5 nm to about 2 nm in thickness and doped with a dopant selected from the group consisting of phosphorus and arsenic at a dopant concentration of greater than 5×1019 atoms/cc, wherein said first layer of Ge is positioned below said channel and extends through said source and drain regions.
A field effect transistor comprising:
- a single crystal substrate,
- a first layer of Ge from about 0.5 nm to about 2 nm in thickness and doped with a dopant selected from the group consisting of phosphorus and arsenic at a dopant concentration of greater than 5×1019 atoms/cc, wherein said first layer of Ge is formed on said substrate,
- a second layer of undoped SiGe epitaxially formed on said first layer,
- a third layer of strained undoped semiconductor material selected from the group consisting of Si and SiGe,
- a source region and a drain region with a channel therebetween, and
- a gate electrode above said channel to control charge in said channel.
A field effect transistor comprising
- a single crystal substrate,
- an oxide layer formed on said substrate having an opening,
- a gate dielectric and gate electrode formed in said opening over said substrate,
- a source and drain region formed in said substrate aligned with respect to said gate electrode,
- a dielectric sidewall spacer formed on either side of said gate electrode and above a portion of said source and drain regions,
- a first layer of Ge from about 0.5 nm to about 2 nm in thickness and doped with a dopant selected from the group consisting of phosphorus and arsenic selectively positioned over exposed portions of said source and drain regions,
- a second layer of semiconductor material selected from the group consisting of Si and SiGe doped with a dopant selected from the group consisting of phosphorus and arsenic epitaxially formed over said first layer to form raised source and drain regions.
Dependencies are inferred from the claim text.