An electronic device includes a first chip, a second chip bonded to the first chip with a bump, a first metal pattern provided on a first surface that is a surface of the first chip facing the second chip, and a second metal pattern provided on a second surface that is a surface of the second chip facing the first chip. The first chip has a first transmission region. A transmittance for light of the first transmission region is higher than a transmittance of a region other than the first transmission region in the first chip. The first metal pattern and the second metal pattern overlap the first transmission region in a thickness direction of the first chip and the second chip. The second metal pattern is located outside the first metal pattern in a direction in which the first surface and the second surface extend.

An apparatus comprising an integrated circuit device comprising a fiducial area of a first layer, the fiducial area comprising a metal area and a metal free area; and a plurality of zones that are metal free in multiple layers adjacent to the first layer, wherein the zones are defined by a footprint based on the fiducial area of the first layer and a second fiducial area of a second integrated circuit device, the footprint comprising multiple slits.

A method of processing a substrate that includes: forming an infrared (IR) absorbing separation layer over a first substrate; forming one or more layers over the IR absorbing separation layer; bonding the first substrate and a second substrate at a bonding interface between the one or more layers and the second substrate using a direct bonding technique to form a wafer stack; exposing the wafer stack to an infrared (IR) light irradiation to separate the first substrate from the one or more layers.