Semiconductor device, its manufacturing method and its testing method

A semiconductor device for SiP or PoP for downsizing, a method of manufacturing it, and a testing method suitable for SiP and PoP in which the simplification of a system and the enhancement of its efficiency are achieved are provided. A first semiconductor device including a first memory circuit determined as non-defective and a second semiconductor device including a second memory circuit and a signal processing circuit carrying out signal processing according to a program, determined as non-defective are sorted. The sorted devices are assembled as an integral semiconductor device. On a board for testing, a clock signal equivalent to the actual operation of the semiconductor device is supplied. A test program for conducting a performance test on the first memory circuit is written from a tester to the second memory circuit of the second semiconductor device. In the signal processing circuit, a performance test is conducted on the first memory circuit according to the written test program in correspondence wi