Bonded assembly with integrated temperature sensing in bond layer

An assembly, for example an electrostatic chuck assembly, includes a first member, a second member disposed proximate the first member, a bond layer disposed between the first member and the second member, and at least one optical sensor disposed proximate the bond layer to detect a temperature of the bond layer in a field of view of the at least one optical sensor. The bond layer includes a phosphorescent material and provides a dual function of bonding the second member to the first member and emitting phosphorescent radiation towards the at least one optical sensor. In one form, the first member is an electrostatic chuck member and the second member is a heating plate. The assembly may further include a cooling plate and an additional bond layer disposed between the heating plate and the cooling plate.