Non-destructive testing of semiconductors using acoustic wave method

摘要

A contactless non-destructive technique for measuring at least one surface property of a first semiconductor material surface utilizes an electrically conductive interdigital transducer and a metal plate defined on a piezoelectric material. The metal plate has a window therein and the semiconductor material is positioned with its first surface over the window and facing the exposed piezoelectric material of the window. A radio frequency pulse is applied to the interdigital transducer to generate a surface acoustic wave on the piezoelectric material. This produces a transverse electric field which extends above the surface of the piezoelectric material and propagates across the window. This field acts as a probing field in the semiconductor material at the surface facing the piezoelectric material, and due to acousto-electric interaction a transverse acousto-electric voltage is produced. A dc voltage is applied to an opposite surface of the semiconductor to change the surface potential of the semiconductor material. A characteristic curve plotting the transverse acoustoelectric voltage against the dc voltage can be utilized to determine various surface properties for the semiconductor material. The window also defines the position where this surface property is measured.