The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Apr. 29, 2014
Filed:
Apr. 15, 2011
Srivatsa G. Kundalgurki, Austin, TX (US);
Scott Dye, Austin, TX (US);
Srivatsa G. Kundalgurki, Austin, TX (US);
Scott Dye, Austin, TX (US);
Freescale Semiconductor, Inc., Austin, TX (US);
Abstract
MEMS devices () using etched cavities () are desirably formed using multiple etching steps. Preliminary cavities () formed by locally anisotropic etching to nearly the final depth have irregular () sidewalls () and steep and/or inconsistent sidewall () to bottom () intersection angles (). This leads to less than desired cavity diaphragm () burst strengths. Final cavities () with smooth sidewalls (), smaller and consistent sidewall () to bottom () intersection angles (), and having more than doubled cavity diaphragm () burst strengths are obtained by treating the preliminary cavities () with TMAH etchant, preferably relatively dilute TMAH etchant. In a preferred embodiment, a cleaning step is performed between the etching step and the TMAH treatment step to remove any anisotropic etching by-products present on the preliminary cavities' () initial sidewalls (). The multi-step cavity etching procedure is especially useful for forming robust MEMS pressure sensors, but is applicable to any type of MEMS device.