Pressure sensing elements (壓力 感知 素 子) with a semiconductor device and its manufacturing method

摘要

PURPOSE:To obtain a flat back surface and to make it possible to provide other active elements on a substrate at the peripheral part of a pressure sensing element, by providing a layer, into which high concentration impurities are introduced, on the bottom surface of a thin film part, which is contacted with a concave part that forms the pressure sensing element, thereby controlling the etching speed when the concave part is etched. CONSTITUTION:A photoresist mark 14 is provided at the back surface of a low impurity concentration p type Si substrate 6. Anisotropic etching, which uses alkali etching liquid such as KOH, is performed, and a deep concave part 15 is provided so as to reach an n+ type embedded layer 9. When alkali etching of an impurity doped silicon crystal substrate is performed, the etching speed is quickly lowered when impurity concentration approaches the order of 1019. Therefore, when the etching reaches a high concentration embedded layer, the etching speed is controlled by itself. Therefor partial unevenness of etching caused by foreign matters, dirt, crystal defects, and the like on the back surface of the substrate is eliminated, and the flat etched surface is obtained as the bottom surface of the thin film part.