UBM, Under Barrier Metal is a metal film that provides solderability and wire bondability on the electrodes of the semiconductor wafers. Conventionally, electroless nickel plating by double zincate method has been used for UBM formation. However, depending on the types and the surface conditions of aluminum electrodes, the method is concerned to occur local corrosion, poor plating appearances and/or adhesion problems because of improper pretreatments.
Additionally, as power semiconductors demand higher resistance of electric current and power voltage, high-class heat resistance becomes very important for plating films. Until now, conventional electroless nickel plating films can cause cracks under the use at a high temperature environment. Therefore, we have developed TOP UBP PROCESS W for power device markets considering the use and the mounting at a high temperature.
TOP UBP PROCESS W is developed to form UBM on aluminum electrodes of semiconductor wafers. This process can minimize the local corrosion of aluminum electrodes (pure aluminum, Al-Si, Al-Cu, Al-Si-Cu) and form uniform and minute zincate substitution films. As the result, uniform and highly adhesive plating films can be obtained. Moreover, the plating film obtained from TOP UBP NICORON HRC, an electroless nickel plating solution, has excellent heat resistance and can prevent cracks even after the heat treatment at 400℃. Therefore, it is possible to apply the product to the plating for UBM in order to fabricate the power semiconductors for the next-generation.