Horizontal Die Cracking as a Yield and Reliability Problem in Integrated Circuit Devices

The problem of horizontal silicon die cracking, which can occur in CERDIP packages with glass as a die bonding material, is addressed. This fracture mode has been attributed to the combined effects of mechanical and thermal stresses. The mechanism of the fracture will be proposed and related to both the die edge condition and the die attach process. The saw-and-break die separation method is identified as the prime source of stress raisers and die edge damage. Sudden cooling causes internal thermal stress and mechanical loads in the assembly due to the solidification of the glass die attach medium and the mismatch of the coefficients of thermal expansion in the package components. The development of a nondestructive sequential screening test and accept/reject criteria for devices that are more likely to develop cracks in the field during temperature changes or slight mechanical loading are described. In addition, the results of a quantitative computer analysis are presented. This analysis is based on the finite-element method and is performed to determine temperature distribution and stress levels inside the die as a result of the cooling process. Remedial recommendations for minimizing the problem are outlined.