SEMI MS5 - Test Method for Wafer Bond Strength Measurements Using Micro-Chevron Test Structures
This Test Method enables the determination of the bond strength between two wafers using micro-chevron test structures. Wafer-wafer bonding is a mainstay for microelectromechanical system (MEMS) and three dimensional stacked integrated circuits (3DS-IC) design and fabrication. MEMS components, such as acceleration sensors, gyroscopes, micropumps, or microvalves that are increasingly found in smart automotive and navigation control systems or in medical devices typically use wafer bonding technologies. Due to being subjected to mechanical stresses, the industrial applications of these components require high mechanical strength, low leakage, and high reliability of the wafer-bonded interface. For a knowledge of the strength determining factors (such as fatigue and stress corrosion) of wafer bonding, for quality control, and for the development of new bonding technologies, a method for determining the strength of such bonds is important to producers and users of MEMS devices, of wafer bonding equipment, and of wafer materials.
This Test Method allows determination of the bond-interface strength, using micro-chevron test structures, of bonded wafer materials. The bond-interface strength is expressed in units of energy per unit area and is technically the critical wafer bond toughness. It is restricted to the use of silicon wafers with or without a thin intermediate layer with one geometrical configuration for the micro-chevron test structures.
The processing of the micro-chevron test structures (including steps such as the etching used to create the micro-chevron pattern, the bonding of the wafers, and the sawing of the bonded wafers) is beyond the scope of this Test Method. Although these steps are discussed in general terms, this Test Method does not recommend etching, bonding, or sawing techniques, rather, it is used to ascertain the bond strength once the wafers are bonded. Therefore, this Test Method can be used to determine a preferred bonding technique.
This Test Method can be used to obtain the on-wafer spatial distributions of wafer bond strength.
Referenced SEMI Standards