Formation of an asymmetric trench in a semiconductor substrate and a bipolar semiconductor device having an asymmetric trench isolation region
US9231089B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Apr 23, 2015 |
| Grant date | Jan 5, 2016 |
| Priority date | — |
| Expiry date | Apr 23, 2035 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH10D62/83
- WIPO fieldSemiconductors
- WIPO sectorElectrical engineering
Abstract
Disclosed is a trench formation technique wherein an opening having a first sidewall with planar contour and a second sidewall with a saw-tooth contour is etched through a semiconductor layer and into a semiconductor substrate. Then, a crystallographic wet etch process expands the portion of the opening within the semiconductor substrate to form a trench. Due to the different contours of the sidewalls and, thereby the different crystal orientations, one sidewall etches faster than the other, resulting in an asymmetric trench. Also disclosed is a bipolar semiconductor device formation method that incorporates the above-mentioned trench formation technique when forming a trench isolation region that undercuts an extrinsic base region and surrounds a collector pedestal. The asymmetry of the trench ensures that the trench isolation region has a relatively narrow width and, thereby ensures that both collector-to-base capacitance Ccb and collector resistance Rc are minimized within the resulting bipolar semiconductor device.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.