Method for enhancing the solubility of dopants in silicon

Patent · Tue Sep 30 00:00:00 EDT 2003

OSTI ID:1174513

Sadigh, Babak; Lenosky, Thomas J.; De La Rubia, Tomas Diaz

A method for enhancing the equilibrium solid solubility of dopants in silicon, germanium and silicon-germanium alloys. The method involves subjecting silicon-based substrate to biaxial or compression strain. It has been determined that boron solubility was largely enhanced (more than 100%) by a compressive bi-axial strain, based on a size-mismatch theory since the boron atoms are smaller than the silicon atoms. It has been found that the large enhancement or mixing properties of dopants in silicon and germanium substrates is primarily governed by their, and to second order by their size-mismatch with the substrate. Further, it has been determined that the dopant solubility enhancement with strain is most effective when the charge and the size-mismatch of the impurity favor the same type of strain. Thus, the solid solubility of small p-type (e.g., boron) as well as large n-type (e.g., arsenic) dopants can be raised most dramatically by appropriate bi-axial (compressive) strain, and that solubility of a large p-type dopant (e.g, indium) in silicon will be raised due to size-mismatch with silicon, which favors tensile strain, while its negative charge prefers compressive strain, and thus the two effects counteract each other.

• Research Organization: The Regents of the University of California, Oakland, CA (United States),; Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States)
• Sponsoring Organization: USDOE
• DOE Contract Number: W-7405-ENG48
• Assignee: The Regents of the University of California (Oakland, CA)
• Patent Number(s): 6,627,522
• Application Number: 09/945,878
• OSTI ID: 1174513
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE