JPS6468932A - Dry etching - Google Patents

Abstract

PURPOSE:To set the optimum etching conditions, by forming a hole for monitoring in a an element isolating oxide film in addition to a contact hole in a resist film for the contact hole, performing dry etching, and computing the amount of over etching of a silicon substrate based on the etching speed ratio between the oxide film and the silicon substrate. CONSTITUTION:A monitoring hole 6 is provided on an element isolating SiO2 film 2. A photoresist film 4, in which a contact hole 5 and the monitoring hole 6 are formed, is used as a mask, and dry etching is performed. After the etching, the thickness of the element isolating SiO2 film 2 at the monitoring hole 6 is measured. There is an etching speed ratio, which is determined by the etching conditions, between the etching amount of the SiO2 film 2 (b) and the etching amount of a silicon substrate 1 (a). The etching amount of the silicon substrate 1 can be computed based on said relation. For example, when the optimum etching amount of the silicon substrate 1 is To, the etching amount of the SiO2 film 2 is to. When the etching amount of the SiO2 film 2, which is measured now, is (t), the etching amount of the silicon substrate 1 at this time is estimated as T. Therefore, the etching conditions are set so as to obtain the optimum etching amount To for the silicon substrate.