SEMICONDUCTOR STRUCTURE WITH SINGLE CRYSTAL MEMBER LYING ABOVE CAVITY PROVIDED TO SEMICONDUCTOR BOARD AND PROCESS THEREFOR

摘要

PROBLEM TO BE SOLVED: To realize a sensor such as an accelerometer which is useful for the detection of lateral acceleration and built on the surface bulk silicon of a semiconductor board. SOLUTION: A process where a sensor 10 such as an accelerometer 10 is formed comprises a first step where an epitaxial layer 14 is formed on a semiconductor board 12 and a second step where single crystal fingers 20 and 22 are provided by partly patterning the epitaxial layer 14. The heights 4 to 3 of the fingers 20 and 22 are at least twice as large as their width 4 to 4. The above process comprises a step where a cavity (40) is provided under a part of the fingers 20 and 22 so as to expose the bases of the fingers 20 and 22 using etching agent which is possessed of an etching selection ratio of the semiconductor board 12 to the epitaxial layer 14 is set above about 10:1. A distance 4 to 2 from the base of the cavity to the above member is larger than about 5μm.