Quality and reliability impact of defect data analysis

Abstract

In the last decade we have seen a shift towards a broader application of information on IC manufacturing defects.Here an overview will be given of the methods used to gather data on the defects with a focus on local defects in the interconnection layers. Next this information is applied to determine a model describing the geometrical aspects of such defects. This model is used to come to the definition of hard faults and soft faults and to derive a relationship between the relative number of occurrence for either fault. Because the electrical impact of some of the soft faults will be closely related to the behavior of small open circuits or gate-oxide shorts, this relationship is an indication for the amount of quality and reliability problems.

Critical area extraction for soft fault estimation

“…For a regular array of tracks of width and separation the sensitivity to hard faults , for defects with diameter , is given by for for for (1) The sensitivity to both hard and soft (H&S) faults [2] is given by for for for (2) Taking a of , as a conservative definition of the defect size that can cause a soft fault, and gives the sensitivity function shown in Fig. 2.…”

“…This deterioration is related to both the thickness of the remaining dielectric and on the level of electrical activity at the affected nodes. It has been suggested that a minimum safe distance is half of the minimum track separation [2].…”

“…This can be a useful metric for comparing the defect sensitivity of integrated circuit layouts, giving a measure of all the faults that must be discovered by test procedures to eliminate defect related lifetime faults. The second term in (4) can also be used to assess the susceptibility of a layout to long-term defect-related reliability problems [2].…”

“…These faults are difficult to detect during test and a proportion of them will deteriorate throughout the life of the device, resulting in reliability problems [2].…”

“…This paper presents a method of extracting the critical area of soft faults, that have been proposed as a source of reliability problems, using the fault model reported by Bruls [2]. Other work has reported that soft faults have an effect on Manuscript received March 20, 1996; revised April 7, 1997.…”