A computer program product for implementing a scan chain to test a semiconductor including one or more computer-readable storage media and program instructions stored on the one or more computer-readable storage media, the program instructions including: program instructions to obtain an initial structure of the scan chain, program instructions to determine, according to function modules of the semiconductor corresponding to scan registers on the scan chain, at least one scan register pair with backward dependency, program instructions to adjust the initial structure of the scan chain such that the at least one scan register pair with backward dependency becomes a scan register pair with forward dependency, and program instructions to determine a key subset of a fan-out scan register in the at least one scan register pair with backward dependency.