Semiconductor devices

A semiconductor device includes an error check and scrub (ECS) command generation circuit and an ECS control circuit. The ECS command generation circuit is configured to generate an ECS command by controlling a speed of a first counting operation that is performed based on a refresh command or a bank refresh command, according to a temperature and a refresh mode of the semiconductor device, or is configured to generate the ECS command by performing a second counting operation based on a periodic signal. The ECS control circuit is configured to sequentially generate an ECS active command, an ECS read command, an ECS write command, an ECS pre-charge command, and an end signal based on the ECS command. The refresh mode includes a fine granularity refresh (FGR) mode, and the temperature includes a high temperature that is a temperature above a certain temperature.