Processor for controlling substrate biases in accordance to the operation modes of the processor

A semiconductor integrated circuit device comprising:

• a logic circuit including at least one transistor, which has at least a first mode and a second mode;
• a substrate bias voltage control circuit which controls a substrate bias voltage applied to the at least one transistor;
• and
• an operation mode control circuit which operates in response to execution of an instruction to proceed to the first mode or interruption to proceed to the second mode;
• wherein the operation mode control circuit controls the substrate bias voltage in response to execution of the instruction so that the substrate bias voltage is controlled to be a first voltage in the first mode;
• wherein the operation mode control circuit controls the substrate bias voltage in response to interruption so that the substrate bias voltage is controlled to be a second voltage in the second mode, a threshold voltage of the at least one transistor applied with the first voltage is higher than a threshold voltage of the at least one transistor applied with the second voltage;
• wherein the logic circuit is controlled not to change input of the logic circuit in response to execution of the instruction;
• and
• wherein the logic circuit starts to operate after the substrate bias voltage applied to the at least one transistor is stabilized to a predetermined level, after interruption.