Method to form mosfet with an inverse T-shaped air-gap gate structure
US5869374A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Apr 22, 1998 |
| Grant date | Feb 9, 1999 |
| Priority date | — |
| Expiry date | Apr 22, 2018 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH10D62/371
- WIPO fieldSemiconductors
- WIPO sectorElectrical engineering
Abstract
A method for fabricating a MOS transistor with an inverse T-shaped air-gap gate structure on a semiconductor substrate is disclosed. The T-shaped air-gap gate structure reduces the parasitic resistance and capacitance; hence device structure operation speed can be improved. The method comprises the following steps: firstly, a gate hollow is defined in the pad oxide/nitride layer. Next an ultra-thin nitrogen rich dielectric as a gate oxide is formed. After that, a thin .alpha.-Si is deposited, then an ion implantation is done to form a punchthrough stopping region. After forming a CVD oxide film, an anisotropic etching is followed to form oxide spacers. An undoped silicon layer then followed to refill the gate hollow region. A CMP processes or a dry etching is done to remove silicon layer until the nitride layer is exposed. Subsequently, the oxide spacers is removed to expose a dual hollow. A LDD implantation is then implanted into the substrate. Next a pad nitride/oxide layer is successive removed to expose the substrate by a dry etching method. Subsequently, a source/drain/gate implantation and a hight temperature oxidation are carried out to grow an oxide layer and seal the dual …
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.