Bonded body, ceramic circuit substrate, and semiconductor device

A bonded body, comprising:

• a ceramic substrate;
• a copper plate;
• and
• a bonding layer located on at least one surface of the ceramic substrate,
• the bonding layer bonding the ceramic substrate and the copper plate,
• the bonding layer including
• a Ti reaction layer including titanium nitride or titanium oxide as a major component,
• a plurality of first alloys positioned between the Ti reaction layer and the copper plate, each of the plurality of first alloys including at least one selected from a Cu—Sn alloy and a Cu—In alloy, at least a portion of the plurality of first alloys being a Cu—Sn alloy, and
• a second alloy positioned between the Ti reaction layer and the copper plate, the second alloy being a Ti—Sn alloy,
• the plurality of first alloys having mutually-different Sn concentrations or In concentrations,
• a total surface area of the plurality of first alloys being greater than a total surface area of the second alloy based respectively on average values analyzed in three regions,
• each of the three regions being a thickness of the bonding layer×40 μm in a width direction,
• the at least a portion of the plurality of first alloys and the second alloy detected by EDX point analysis of the bonding layer being within a region of a ternary phase diagram of Cu, Sn, and Ti surrounded with (97, 3, 0), (60, 40, 0), (2, 40, 58), and (39, 3, 58).