Formation of Silicon-Gold Eutectic Bond Using Localized Heating Method

A new bonding technique is proposed by using localized heating to supply the bonding energy. Heating is achieved by applying a dc current through micromachined heaters made of gold which serves as both the heating and bonding material. At the interface of silicon and gold, the formation of eutectic bond takes place in about 5 minutes. Assembly of two substrates in microfabrication processes can be achieved by using this method. In this paper the following important results are obtained: 1) Gold diffuses into silicon to form a strong eutectic bond by means of localized heating. 2) The bonding strength reaches the fracture toughness of the bulk silicon. 3) This bonding technique greatly simplifies device fabrication and assembly processes.