Power storage element, manufacturing method thereof, and power storage device

A power storage device comprising:

• a transistor over a substrate;
• and
• a power storage element over the transistor,
• wherein the power storage element comprises:
• a positive electrode and a negative electrode over the substrate;
• a solid electrolyte layer over and in contact with the positive electrode and the negative electrode;
• a carrier supplying layer over the solid electrolyte layer;
• and
• a sealing layer over the positive electrode, the negative electrode, the solid electrolyte layer, and the carrier supplying layer,
• wherein the transistor is electrically connected to one of the positive electrode and the negative electrode,
• wherein the positive electrode and the negative electrode are arranged in a same plane,
• wherein the positive electrode comprises a first metal and an oxide of the first metal, and the negative electrode comprises a second metal and an oxide of the second metal, and
• wherein the oxide of the first metal covers an upper surface and side surfaces of the first metal, and the oxide of the second metal covers an upper surface and side surfaces of the second metal.

A manufacturing method of a power storage element, comprising:

• forming a first metal layer and a second metal layer over a substrate;
• performing oxidation treatment on the first metal layer and the second metal layer to form a first metal oxide layer on an upper surface and side surfaces of the first metal layer and a second metal oxide layer on an upper surface and side surfaces of the second metal layer;
• forming a solid electrolyte layer over and in contact with the first metal oxide layer and the second metal oxide layer;
• forming a carrier supplying layer over the solid electrolyte layer;
• and
• forming a sealing layer over the first metal oxide layer, the second metal oxide layer, the solid electrolyte layer, and the carrier supplying layer,
• wherein the first metal layer and the second metal layer are arranged in a same plane.