Laser processing method for thin film structures

A method of processing a thin film structure comprising:

• providing the thin film structure comprising a stack of two or more thin film layers supported on a surface of a substrate, the stack having a depth orthogonal to the surface of the substrate;
• forming a cut having a cut line width through the depth of the stack by using a direct write laser technique to scan a laser beam having a laser beam diameter or a spot width along a scan path covering an area of a desired cut line on a surface of the stack to ablate a material of the stack by creating a plasma from the material along the cut line and through the depth of the stack at least to the surface of the substrate, wherein the laser beam diameter is smaller than the cut line width and the laser beam is scanned relative to the cut line width as well as along its length to remove a required width of material;
• wherein the direct write laser technique is implemented using an ultrashort pulsed laser outputting pulses with a duration of 1000 femtoseconds or less, at a wavelength in a range of 100 to 1500 nm, and delivering a fluence in a range of 50 to 100,000 mJ/cm2;
• and further wherein the spot width of the laser beam is 0.001 to 0.1 mm and the cut line has a width of 0.015 to 2 mm;
• the method further comprising the steps of, after forming the cut through the depth of the stack, applying a layer of dielectric material to cover the surface of the stack, as well as to cover one or more side walls and a base of the cut;
• and
• subsequently slicing through a remaining thickness of the substrate at the base of the cut.