Method for pre-processing semiconducting thermoelectric materials for metallization, interconnection and bonding

A thermoelectric device, comprising:

• a number of N thermoelectric elements of semiconducting thermoelectric conversion material doped to n-type conductivity and a number of N thermoelectric elements of semiconducting thermoelectric conversion material doped to p-type conductivity, where N is an integer from 1 to n,
• a number of 2N+1 electric contact elements comprising a first bonding layer of a metal A and a second bonding layer of a metal B, and
• a first substrate in thermal contact with a heat reservoir and second substrate in thermal contact with a heat sink,
• where
• the N thermoelectric elements of n-type conductivity and the N thermoelectric elements of p-type conductivity are electrically connected in series by the 2N+1 electric contact elements,
• the thermoelectric elements are bonded to the electric contact elements by solid liquid interdiffusion bonds, and
• the thermoelectric elements are on a first side in thermal contact with the first substrate in thermal contact with a heat reservoir, and on a second side opposite the first side, the thermoelectric elements are on a second side opposite the first side in thermal contact with the second substrate in thermal contact with a heat sink, characterised in that
• each of the N thermoelectric elements of n-type conductivity and the N thermoelectric elements of p-type conductivity have on their first and second surface:
• i) a first adhesion layer of a first metal deposited directly onto the first and second surfaces,
• ii) a diffusion barrier layer of a non-metallic compound of a second metal deposited directly onto the first adhesion layer on the first and second surfaces,
• iii) a second adhesion layer of a third metal deposited directly onto the diffusion barrier layer of the non-metallic compound of the second metal on the first and second surfaces,
• iv) a first bonding layer of a metal A deposited directly onto the second adhesion layer on the first and second surfaces, and
• v) a second bonding layer of a metal B deposited directly onto the first bonding layer the on the first and second surfaces,
• where
• the non-metallic compound of the second metal is either a nitride or an oxide of the second metal,
• the melting point of metal A is higher than metal B and metal B is chemically reactive towards metal A at their common interface when subject to heating above the melting point of metal B, and
• the solid liquid interdiffusion bonds are formed by laying the second bonding layer of metal B of the thermoelectric elements and the electric contact elements, respectively, facing and contacting each other followed by an annealing which causes metal B of the second bonding layer to melt and reacting with metal A of the first bonding layer.