US Patent 9496189 Stacked semiconductor devices and methods of forming same

Stacked semiconductor devices and methods of forming the same are disclosed. First tier workpieces are mounted on a top surface of a semiconductor device to form first tier stacks, the semiconductor device comprising one or more integrated circuit dies, the semiconductor device having one or more test pads per integrated circuit die on the top surface of the semiconductor device. Each of the first tier stacks is electrically tested to identify first known good stacks and first known bad stacks. Second tier workpieces are mounted atop the first known good stacks, thereby forming second tier stacks. Each of the second tier stacks is electrically tested to identify second known good stacks and second known bad stacks. Stacking process further comprises one or more workpiece mounting/testing cycles. The stacking process continues until the stacked semiconductor devices comprise desired number of workpieces.