Detecting material transition in semiconductor structure

摘要

A process for material transition detection in semiconductor structures during an anisotropic plasma deep etch-structuring process, involving successive alternate etching and masking (or deposition) steps, comprises (a) determining the concentration of one or more specific materials in the plasma as a function of time by means of intensity measurement; (b) determining the beginning of each etching step by attainment of a fixed intensity peak value (W); (c) when the peak value (W) is attained, beginning a delay time ( tau ) of longer duration than that of a first intensity maximum (1) which is not characteristic of the material transition, thus allowing this first intensity maximum (1) to be ignored during transition detection; (d) after expiry of the delay time ( tau ), determining a second intensity maximum (2) which is characteristic of the transition; and (e) monitoring the second intensity maxima (2) of the etching steps for detecting the transition when the maxima are greater than or less than a preset value.