Method for photolithographic definition of recessed features on a semiconductor wafer utilizing auto-focusing alignment
US5783340A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jul 31, 1997 |
| Grant date | Jul 21, 1998 |
| Priority date | — |
| Expiry date | Jul 31, 2017 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01P2015/0828
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
A method is disclosed for photolithographically defining device features up to the resolution limit of an auto-focusing projection stepper when the device features are to be formed in a wafer cavity at a depth exceeding the depth of focus of the stepper. The method uses a focusing cavity located in a die field at the position of a focusing light beam from the auto-focusing projection stepper, with the focusing cavity being of the same depth as one or more adjacent cavities wherein a semiconductor device is to be formed. The focusing cavity provides a bottom surface for referencing the focusing light beam and focusing the stepper at a predetermined depth below the surface of the wafer, whereat the device features are to be defined. As material layers are deposited in each device cavity to build up a semiconductor structure such as a microelectromechanical system (MEMS) device, the same material layers are deposited in the focusing cavity, raising the bottom surface and re-focusing the stepper for accurately defining additional device features in each succeeding material layer. The method is especially applicable for forming MEMS devices within a cavity or trench and integrating the …
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.