| 摘要 |
PURPOSE:To improve the ohmic characteristics by a method wherein a silicon wafer etched with KOH is temporarily washed and after neutralizing the etched part with acid base chemical and ultrasonic washing the same, an electrode layer is formed by evaporating process. CONSTITUTION:An N<-> type epitaxial layer 2 is grown on an N-type silicon wafer 1 and then a P-type impurity region 3 is buried in the epitaxial layer 2. The surface of epitaxial layer 2 is coated with a silicon oxide film 4 while a part of the silicon oxide film 4 on the surface of region 3 is opened to be coated with a P-type surface electrode layer 5. A thin natural oxide film 6 is formed by mechanically grinding the backside of wafer 1. The natural oxide film 6 on the ground surface is removed by immersing the wafer 1 in KOH contained in an etching vessel at constant temperature of around 40-60 deg.C for slightly etching the ground surface. next, the wafer 1 is temporarily washed and after cleansing with acid base chemical to be ultrasonic washed. Finally, after centrifugal drying process, a backside electrode layer 7 is formed on the ground surface by evaporating process. Through these procedures, the electrode layer 7 is provided with excellent ohmic characteristics to the silicon wafer 1 while improving the bonding strength.
|
