Oxygen assisted ohmic contact formation to n-type gallium arsenide
US5358899A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Feb 9, 1994 |
| Grant date | Oct 25, 1994 |
| Priority date | — |
| Expiry date | Feb 9, 2014 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH10D64/62
- WIPO fieldSemiconductors
- WIPO sectorElectrical engineering
Abstract
This invention describes a low resistance contact structure to n-type GaAs and a method for making such a contact structure. The contact structure is formed by depositing successive layers of Ni, Au, Ge, and Ni. A fifth layer is then deposited on the first four layers. The fifth layer is a metallic tungsten oxide. The metallic tungsten oxide is formed by sputtering tungsten onto the 4 layer stack in a low pressure argon plus oxygen atmosphere. The resulting 5 layer stack is then annealed in a rapid thermal anneal (RTA) process. The RTA process heats the stack for 5 seconds at 600 degrees. The resulting structure consists of an intermetallic NiGe compound having a small amount of a AuGa compound dispersed within it and being covered by a metallic tungsten oxide film. The oxygen from the metallic tungsten oxide film acts as a gettering mechanism to create gallium vacancies in the GaAs lattice structure during the RTA process. The oxygen forms a compound with gallium which is sandwiched between the metallic tungsten layer and the NiGe metallurgy. The sheet resistance of the contact metallurgy is low because the metallic tungsten oxide film is substantially thicker than that required t…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.