US Patent 10339994 Semiconductor device

A semiconductor device according to an aspect of die present invention has: a plurality of memory cells MC; a plurality of word lines WL each coupled to a corresponding one of the plurality of memory cells MC; and a control circuit that intermittently monitors accesses to, the plurality of word lines WL, stores/erases some captured row-addresses in a first number of registers, and detects, by comparison with stored addresses, in response to a first number of accesses to one of the word lines WL a first period of time. According to the present invention, access histories can be precisely analyzed by a small-scale circuit configuration, and measures against, for example, the Row Hammer problem, etc. can be taken.