METHOD OF ELIMINATING THIN FILM AT PART OF LAMINATED SUBSTRATE WHERE BONDING IS NOT COMPLETED

摘要

PURPOSE:To prevent contamination caused by exfoliation in a heat-treating process by a method wherein, after a plurality of semiconductor substrates are stuck, and one substrate is made a thin film of 100mum or less in thickness, the thin film at a part where bonding is not completed is eliminated by applying ultrasonic wave energy in liquid. CONSTITUTION:An oxide film is stuck on the surface of a substrate 1a to be stuck. On the other hand, the surface of a sticking substrate 1b doped with specified impurity is mirror-polished. The polished surface is cleaned, made hydrophilic, and brought into contact with the oxidized surface of the substrate 1a to be stuck, which are unified in a body. After that, by heat treatment in a nitrogen atmosphere at 1100 deg.C, a laminated substrate 1 is obtained which has bonding strength comparable with bulk silicon. The sticking substrate 1b is polished, and turned into a thin film 1c of 100mum or less in thickness. By using an ultrasonic wave applying apparatus, the thin film at a part where bonding is not completed is eliminated. The intensity of the ultrasonic wave may be 0.2W/cm2. Thereby, the thin film less than 2mm in thick ness at a part where bonding is not completed can easily be eliminated. Since the exfoliation of the thin film at a part where bonding is not completed is not generated in a heat-treating process, a clean processing can be maintained.