Abstract: A method of fabricating a SOI wafer using an isolation film as a polishing stopper, comprising the steps of: preparing a first and a second silicon substrates; implanting impurities into selected active regions of the first silicon substrate to a desired depth; etching the portion of the silicon substrate between the active regions to forming trenches having a desired depth; forming a first insulating layer of an oxide film on the first silicon substrate to be filled in the trenches; etching-back the first insulating layer to form a trench type isolation film; forming a second insulating layer of an oxide film on the first silicon substrate including the isolation film; bonding the first and the second silicon substrates to contact the second insulating layer with the second silicon substrate; firstly polishing the first silicon substrate by the vicinity of the portion of the first silicon substrate where the impurities are implanted; etching the polished first silicon substrate by using an etchant until the