Method for fabricating an SOI device in alignment with a device region formed in a semiconductor substrate

A method of forming a semiconductor-on-insulator device, comprising the steps of:

• forming a first alignment mark on an upper major surface of a semiconductor substrate at a first reference position;
• forming a device region in the semiconductor substrate at a position located a selected distance from the first alignment mark, said device region including a diffusion region having an impurity element;
• providing an insulator layer on the upper major surface of the semiconductor substrate, said insulator layer having an upper major surface with a depression therein at the first reference position in correspondence with the first alignment mark, said insulator layer being configured so as to expose a part of the upper major surface of the semiconductor substrate;
• providing a semiconductor layer having corresponding first and second portions respectively on the upper major surface of the insulator layer and on, and in contact with, the exposed part of the upper major surface of the semiconductor substrate, said semiconductor layer having an upper major surface with a first depression therein at the first reference position in correspondence with the first alignment mark;
• recrystallizing the semiconductor layer by heating same to a first temperature, above the melting point temperature of the semiconductor layer, and cooling same subsequently to a second temperature, below the melting point temperature and less than the first temperature, starting from the second portion of the semiconductor layer in contact with the exposed part of the upper major surface of the semiconductor substrate and moving therefrom, laterally along the semiconductor layer, thereby to form a single crystal semiconductor layer having an upper major surface with a second depression therein at a second, different reference position;
• and
• patterning the single crystal semiconductor layer using the second depression in the upper major surface of the semiconductor layer as a second alignment mark and thereby to form a semiconductor device in alignment with the device region in the semiconductor substrate, the first reference position of said first alignment mark being offset from the second reference position of the second alignment mark by an amount corresponding to, and thereby cancelling out, the expansion of the single crystal semiconductor layer caused by the recrystallizing step.