Method for forming field effect transistors having different threshold voltages and devices formed thereby
US5907777A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jul 31, 1997 |
| Grant date | May 25, 1999 |
| Priority date | — |
| Expiry date | Jul 31, 2017 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH10D84/0144
Abstract
The preferred embodiment provides a method for fabricating field effect transistors that have different threshold voltages without requiring excessive masking and other fabrication steps. In particular, the method facilitates the formation of FETs with different threshold voltages by doping the gate dielectric with various amounts of ions. This provides a built in potential in the gate dielectric proportional to the amount of ions in the gate dielectric. This potential changes the threshold voltage of the FET. Thus, by selectively doping the gate dielectric with ions the threshold voltage of a FET can be changed. The selective doping of many FETs to many different threshold voltages can be done with only one additional masking step. Thus, the present invention provides the ability to form FETs having different threshold voltages without requiring excessive process complexity.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.