The Chemistry of Failure Analysis

This paper discusses the chemistry of failure analysis in sufficient detail to serve as a practical guide for the failure analyst. It includes a discussion of the chemistry of plastic composition formulation. This discussion is preparatory to the main body of the paper which covers the chemistry and mechanics of decapsulation and, also, an explanation of the principles of chemical etch of semiconductor building blocks and interconnect materials. Included in the paper is a general procedure of decapsulation and several examples are contained in Table 1. Source materials are cited that will provide additional information on actual decapsulation procedures for thermoplastics and single and composite thermo-setting encapsulation systems. The list of chemicals employed in failure analysis has evolved over the years into a rather impressive list of toxic and extremely dangerous organic and inorganic chemicals. These chemicals when mixed in the proper proportions and used in appropriate environmental conditions are capable of selectively removing plastic encapsulations and semiconductor building blocks to uncover semiconductor failure mechanisms. The safe use of these chemicals and others that may be presented in the future can and will provide the analyst with an excellent tool for determining the precise cause of failure.