Defect size distribution in VLSI chips

Very large scale integration (VLSI) patterns consisting of parallel lines of polycrystalline Si have been fabricated and electrically tested for shorts. The number of observed shorts was related to the line spacings by using an analytical model for defect-sensitive pattern areas. It was found that the simple defect size distribution function h(x)=k×x ^-n used previously with values of n around three, projects that total number of shorts arising from a given defect density with reasonable accuracy. However, actual defect size distributions observed microscopically are bimodal or multimodal. This complication has only a minor influence on the results projected by the model because the smaller defects are more numerous than the larger ones that make up the secondary distributions