Adhesion quantification methods for wafer bonding

Integrated circuit technology and its later development, microsystem technology, make good use of wafer bonding. An increased interest in bond adhesion quantification can be anticipated when wafer bonding is optimized for complex microelectro-mechanical systems where the bonding process must take every other component into consideration when it comes to cost, temperature budget and process compatibility. Adhesion quantification methods for evaluation of bonded brittle material, especially direct wafer bonded, are reviewed in this paper. The most commonly utilized methods, namely the double cantilever beam, tensile, chevron and blister test methods, are thoroughly covered and miscellaneous techniques are mentioned. The physics background and modeling presented by different authors are examined. Based on models and experiences made in neighboring research fields improvements are suggested. Practical capabilities and limitations and origin and mitigation of measurement errors are addressed. Experimental foundation on fundamental knowledge in solid mechanics and the statistical nature of brittle fracture behavior is emphasized. The methods’ adequacy are compared and ranked for three types of uses: general understanding, bonding process optimization and quality control. It is shown that the quality of all commonly used methods for adhesion quantification of wafer bonding can be dramatically improved by small means.