High threshold NMOS source-drain formation with As, P and C to reduce damage
US7736983B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Jan 10, 2008 |
| Grant date | Jun 15, 2010 |
| Priority date | — |
| Expiry date | Apr 26, 2028 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH10D84/038
- WIPO fieldSemiconductors
- WIPO sectorElectrical engineering
Abstract
Pipe defects in n-type lightly doped drain (NLDD) regions and n-type source/drain (NDS) regions are associated with arsenic implants, while excess diffusion in NLDD and NSD regions is mainly due to phosphorus interstitial movement. Carbon implantation is commonly used to reduce phosphorus diffusion in the NLDD, but contributes to gated diode leakage (GDL). In high threshold NMOS transistors GDL is commonly a dominant off-state leakage mechanism. This invention provides a method of forming an NMOS transistor in which no carbon is implanted into the NLDD, and the NSD is formed by a pre-amorphizing implant (PAI), a phosphorus implant and a carbon species implant. Use of carbon in the NDS allows a higher concentration of phosphorus, resulting in reduced series resistance and reduced pipe defects. An NMOS transistor with less than 1·1014 cm−2 arsenic in the NSD and a high threshold NMOS transistor formed with the inventive method are also disclosed.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.