Laser dicing for singulation

A method, comprising:

• placing a semiconductor wafer in a laser machine, the semiconductor wafer including semiconductor device dies formed on a device side of the semiconductor wafer, the semiconductor device dies separated by scribe streets of the semiconductor wafer and having a metal layer covering a portion of the scribe streets;
• focusing a laser beam through a non-device side of the semiconductor wafer that is opposite the device side, the laser beam focused through the non-device side of the semiconductor wafer to a first focal depth in the metal layer in the scribe streets, the laser beam at a first power level sufficient to ablate metal in the metal layer;
• scanning the laser beam across the scribe streets on the semiconductor wafer between semiconductor device dies;
• and
• ablating the metal layer in the scribe streets.

A method of singulating semiconductor device dies, comprising:

• applying a dicing tape over a metal layer covering a portion of a surface of scribe streets on a device side of a semiconductor wafer that includes semiconductor device dies formed thereon separated from one another by the scribe streets on the semiconductor wafer, the semiconductor wafer having a non-device side opposite the device side;
• placing the semiconductor wafer with the device side facing away from a laser in a stealth dicing machine;
• adjusting a power of a laser beam in the stealth dicing machine to a first power level;
• focusing the laser beam through the non-device side of the semiconductor wafer to a first focal depth in the metal layer in a scribe street;
• scanning the laser beam across the scribe streets between the semiconductor device dies on the semiconductor wafer and ablating the metal layer from the scribe streets;
• adjusting the power of the laser beam to a second power level;
• focusing the laser beam through the non-device side of the semiconductor wafer to a second focal depth in the semiconductor material of the semiconductor wafer;
• scanning the laser beam across the scribe streets between the semiconductor device dies on the semiconductor wafer and forming polycrystalline regions in the scribe streets;
• stretching the dicing tape to propagate cracks through the semiconductor wafer in the scribe streets between the semiconductor device dies to separate the semiconductor device dies one from another;
• and
• removing the dies from the dicing tape.