1.  Field
This disclosure relates generally to semiconductor device packaging, and more specifically, to die bonding used in semiconductor device packaging. 
2.  Related Art
The functionality of semiconductor devices continues to provide very significant utility.  Because of the very small size of the die that makes a semiconductor device, the interface with the system of which it is a part is very important.  Also the ability to dissipate heat can be very significant.  Generally, the die is attached to something rigid that is useful in providing an interface with a system and also may be useful in dissipating heat.  In one type of case the die is bonded to a substrate which is useful for physical support and as a heat sink for heat dissipation.  An effective way this is done is to bond the metal to the die through a gold/silicon (AuSi) eutectic bond.  The back of the die is coated with gold.  The substrate may have a first coating that functions as a barrier and a second coating of gold on the first coating.  A common composition for the barrier is cobalt and nickel.  The gold layers are pressed together and heated to form a eutectic bond to provide physical attachment and for conducting heat.  This may provide the desired functions but the gold is quite expensive.  Cost continues to be important so there is a need for a lower cost die bond.