Laser chip separation method for GaAs MMIC wafers

A chip separation process is described that uses a Nd-YAG laser with the wafer mounted on stretchable tape for machine sort and load for GaAs monolithic microwave integrated circuit (MMIC) wafers. This method is considered especially suitable for prototype masks with multiple-chip design. One of the major advantages of this technique is that the laser can be programmed to cut any pattern desired such that the different circuits need not be laid out in a straight grid pattern as required for sawing. One hundred percent (100%) chip separation yield with no chipping or cracking has been demonstrated. The complete laser chip-separation process consists of eight steps: front scribe alley etch, backside lopping, wafer test, wafer mounting, protective coating for optimal die separation, laser cutting, protective coat removal, and stretch and frame for sorting and chip loading. The process steps are described, and the method´s advantages are noted.<>