Recording element substrate, method of manufacturing the recording element substrate, and liquid ejection head

A recording element substrate comprising:

• a substrate;
• an insulating layer disposed on or above the substrate;
• a plurality of heating portions which are arranged on the insulating layer and which produce thermal energy used to eject a liquid;
• and
• a plurality of heat conduction members, each being located between the adjacent heating portions with respect to an arrangement direction of the heating portions, the heat conduction members passing through the insulating layer between a front surface and a back surface of the insulating layer, the heat conduction members having higher thermal conductivity than the insulating layer.

A method of manufacturing a recording element substrate including a substrate, an insulating layer disposed on or above the substrate, and a plurality of heating portions which are arranged on the insulating layer and which produce thermal energy used to eject a liquid, the method comprising:

• supplying a substrate having an insulating layer and a heat conduction layer on one surface of the substrate, the heat conduction layer being composed of a material having higher thermal conductivity than the insulating layer;
• forming a plurality of openings in the insulating layer to expose the heat conduction layer;
• filling the plurality of openings with a material that has higher thermal conductivity than the insulating layer to form a plurality of heat conduction members which are in contact with the heat conduction layer;
• and
• forming the heating portions on the insulating layer between the adjacent heat conduction members so as not to be in contact with the heat conduction members.