The invention relates to the preparation of a thin layer comprising a step in which an interface is created between a layer used to create said thin layer and a substrate, characterized in that said interface is made in such a way that it is provided with at least one first zone (Z1) which has a first level of mechanical strength, and a second zone (Z2) which has a level of mechanical strength which is substantially lower than that of the first zone. Said interface can be created by glueing surfaces which are prepared in a differentiated manner, by a layer which is buried and embrittled in a differentiated manner in said zones, or by an intermediate porous layer.