Semiconductor eutectic alloy metal (seam) technology for fabrication of compliant composite substrates and integration of materials

Abstract

A method of semiconductor eutectic alloy metal (SEAM) technology for integration of heterogeneous materials and fabrication of compliant composite substrates takes advantage of eutectic properties of alloys. Sub,and Sub,are used to represent the two heterogeneous materials to be bonded or composed into a compliant composite substrate. For the purpose of fabricating compliant composite substrate, the first substrate material (Sub,) combines with the second substrate material (Sub,) to form a composite substrate that controls the stress in the epitaxial layers during cooling. The second substrate material (Sub,) controls the stress in the epitaxial layer grown thereon so that it is compressive during annealing. A joint metal (JM) with a melting point of T,is chosen to offer variable joint stiffness at different temperatures. JM and Sub,form a first eutectic alloy at a first eutectic temperature T,while JM and Sub,form a second eutectic alloy at a second eutectic temperature T,. T,and T,are the melting points of Sub,and Sub,respectively. The following condition should be met: T,, T,>T,>T,, T,. After cleaning of Sub,and Sub,JM is deposited on the bonding sides of Sub,and Sub,After preliminary bonding by applying force to press the bonding surfaces together at room temperature, high temperature bonding is subsequently performed, during which the temperature is ramped up to a temperature equal to or higher than T,. During cooling, JM solidifies first, after which two eutectic alloys solidify.