Intrinsic tensile strength charts for the interface were developed as a function of varying moisture content. A new fundamental strategy to test and predict the reliability of critical interfaces in IC’s substrate and packages was demonstrated.

To demonstrate this strategy, a polyimide/nitride/ oxide/Si multilayer system from an IC was chosen and quantitative measure of degradation of in the fundamental tensile strength of interfaces due to controlled environment of moisture, temperature and hold time was presented. The key to afford this strategy is the Laser Spallation Technique which is capable of measuring the fundamental tensile strength and the FTIR spectroscopy which is capable of quantifying the quantity of moisture present in the sample. The strategy allows the prediction and optimization of device reliability during the design phase itself avoiding the time consuming accelerated tests that are presently employed by the industry.

Figure on the left is a schematic of the sample used during experimentation, while the figure on the right is the result of our analysis

The focus of this research is to address fundamental issues related to separation of basic features of lines, squares, and circular patches of varying geometrical dimensions deposited on a mother substrate and understand the mechanism of transfer to a target substrate, including issues of bonding at the landing sites.

To bring out the advantages over traditional approaches, features made from Al, gold, and polysilicon, shall be considered, and transferred to flexible polymeric tapes, and Si wafers. As a demonstration of future potential in constructing MEMS structures, three basic building blocks-a beam bridge, a membrane diaphragm, and an IC circuit on a flexible substrate, that are common to several useful MEMS structures shall be developed.

More information to come shortly!