Method for thermocompression bonding structures

Abstract

A method for thermocompression bonding structures together including structures having different coefficients of thermal expansion, for example, thermocompression bonding optical diode arrays or other semiconductor structures to silicon substrates to form electronic or optoelectronic devices. The method includes aligning and contacting the structures to be interconnected, thermocompressing the structures via their contact pad elements at a bonding temperature, establishing an encapsulation temperature, applying an encapsulant material between the bonded structures, and curing the encapsulant material at the encapsulation temperature. Conventional bonding processes, which treat encapsulation as a separate step apart from bonding processes, melt the bonded assembly together and include at least one thermal cycle in which the bonded assembly is cooled to room temperature and then is re-heated to the encapsulation temperature before applying the encapsulant material. The inventive method eliminates this thermal cycle by including encapsulation as an integral step in the thermocompression bonding process and therefore reduces or eliminates the possibility of damage to bonds or their multi-layered contact elements between the time of bonding and the time of encapsulation. Resultingly, the inventive method advantageously improves the quality and reliability of the resulting bonds within the formed device compared to bonds formed in a conventional manner.