Trench MIS device having implanted drain-drift region and thick bottom oxide and process for manufacturing the same
US7033876B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Dec 19, 2002 |
| Grant date | Apr 25, 2006 |
| Priority date | — |
| Expiry date | Aug 7, 2023 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH10D64/516
- WIPO fieldSemiconductors
- WIPO sectorElectrical engineering
Abstract
A trench MIS device is formed in a P-epitaxial layer that overlies an N+ substrate. In one embodiment, the device includes a thick oxide layer at the bottom of the trench and an N-type drain-drift region that extends from the bottom of the trench to the substrate. The thick insulating layer reduces the capacitance between the gate and the drain and therefore improves the ability of the device to operate at high frequencies. Preferably, the drain-drift region is formed at least in part by fabricating spacers on the sidewalls of the trench and implanting an N-type dopant between the sidewall spacers and through the bottom of the trench. The thick bottom oxide layer is formed on the bottom of the trench while the sidewall spacers are still in place. Therefore, in embodiments where the thermal budget of the process is limited following the implant of the drain-drift region, the PN junctions between the drain-drift region and the epitaxial layer are self-aligned with the edges of the thick bottom oxide. The drain-drift region can be doped more heavily than the conventional “drift region” that is formed in an N-epitaxial layer. Thus, the device has a low on-resistance. The relatively fla…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.