| 摘要 |
To provide a pressure sensor with good reproducibility, a cavern of elliptical outline is etched into a highly conductive monocrystalline n+ doped silicon chip, leaving a thin membrane of an epitaxial layer of elliptical outline, in which the ratio of the elliptical axes is about 2:1 and the elliptical axes extend at an angle of 45 DEG with respect to the (100) and (010) crystal axes; a resistance bridge, which may be formed by boron diffusion or ion implantation, or by transistor integrated circuit technology, is applied to the center of the membrane, having its resistance or transistor, for example FET transistor, branches arranged at the 45 DEG angle with respect to said crystal axes. Etching can be carried out electrochemically in a bath of diluted hydrofluoric acid, utilizing the differential conductivity between the epitaxial layer and an unmasked portion of the doped silicon to leave a membrane of the epitaxial layer; or by chemical etching in a bath of hydrofluoric acid, nitric acid, and acetic acid.
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