Furnace system and method for selectively oxidizing a sidewall surface of a gate conductor by oxidizing a silicon sidewall in lieu of a refractory metal sidewall
US6774012B1 · kind B1 · utility
Assignee
Inventor
Key dates
| Filing date | Nov 8, 2002 |
| Grant date | Aug 10, 2004 |
| Priority date | — |
| Expiry date | Nov 8, 2022 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH01L21/28247
- WIPO fieldSemiconductors
- WIPO sectorElectrical engineering
Abstract
An improved furnace system and method is provided to substantially minimize, if not eliminate, ambient air from entering a heated chamber of the furnace system during a critical processing step. The furnace system can be used in, for example, an oxidation step where ambient air containing oxygen is prevented from entering an atmospheric pressure tube by essentially purging potential leak areas with an inert gas, such as nitrogen, at the critical moment during temperature ramp up and ramp down, and prior to temperature stabilization and the introduction of an oxidizing gas. If oxygen is not present within the tube, then a tungsten sidewall surface of a gate conductor, for example, will not inadvertently oxidize at the critical pre- and post-oxidation moments. However, if steam is present where hydrogen is available with oxygen, the underlying polysilicon sidewall surface will selectively oxidize instead of the overlying tungsten. The inert gas-filled containers are retrofitted to potential leak areas of not only the tube, but also a torch that is used to forward heated gas into the tube.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.