The invention relates to a method according to the part of the surface of the semiconductor body adjoining the opening and which is to be kept free is provided with a cover layer after which the high-crystalline layer is formed by means of a deposition process. The material of the cover layer can then easily be chosen such that it can be selectively etched relative to the silicon underneath. In addition, the cover layer can easily be selectively deposited on the relevant part of the surface because use can be made of an anisotropic deposition process. In such a process the cover layer is not deposited in the hollow and on the bottom of the hollow. It will be apparent that for the high-crystalline layer also other materials can be chosen such as SiGe having such low Ge contents that the SiGe cannot be etched selectively very well compared to the Silicon.