Method for facilitating crack initiation during controlled substrate spalling

A method for removing a material layer from a substrate, said method comprising:

• providing a substrate comprising, from bottom to top, a base portion comprising at least one first material having a first fracture toughness and having an entirely planar topmost surface and a surface portion comprising at least one second material having a second fracture toughness and having a bottommost surface forming an interface with said topmost surface of said base portion, wherein the second fracture toughness differs from the first fracture toughness and wherein a surface step region is located at each vertical edge and on a front side of the substrate, wherein said surface step region comprises a recessed portion of said first material or a region void of said first material;
• forming a stressor layer atop the front side of the substrate;
• and
• removing a material layer from the substrate by spalling, wherein crack propagation occurs only in one of the first material or the second material.