Patent US 11,742,014

A semiconductor device in which a memory region at each level of a memory device can be changed is provided. The semiconductor device includes a memory device including a first and a second memory circuit and a control circuit. The first memory circuit includes a first capacitor and a first transistor which has a function of holding charges held in the first capacitor. The second memory circuit includes a second transistor, a second capacitor which is electrically connected to a gate of the second transistor, and a third transistor which has a function of holding charges held in the second capacitor. The first and the third transistors each have a semiconductor layer including an oxide semiconductor, a gate, and a back gate. The voltage applied to the back gate of the first or the third transistor is adjusted, whereby the memory region of each of the first and the second memory circuit is changed.