a schematic view of the boule or workpiece 10 including the subsurface separation layer 15 produced by ion beam 30 to illustrate the implanted layer and the spiral nature of the process the thickness of sheet 20 and the depth of the implanted layer which would generally be less than a few hundred micrometers are highly exaggerated in the figure compared to the diameter of boule 10 which would normally be of the order of centimeters the resulting sheet or film of material will have a natural tendency to curl a supportive backing or handle is also useful in keeping the film flat in order to prevent cracking of the film when flattened and to minimize film stress due to flattening the boule radius r should satisfy the equation where t is the film thickness e is the modulus of elasticity of the material and u03c3 is the tensile strength of the material due to the brittle nature of materials such as silicon r should generally exceed the quantity on the right hand side of the equation by a substantial factor of safety such as 10 u00d7 another advantage of applying a handle whether permanent or temporary is that tension may be applied to the handle to assist in smooth continuous separation or delamination of the film from the boule this requires that the handle be attached at a point prior to the line where the film separates from the boule alternately various forms of energy may be applied to the boule at this line to induce separation of the film from the bulk this could take the form of a mechanical stressor such as roller similar to the pinch roller 60 or a.