Abstract:The center-satellite model for describing the distribution of defects on wafers is discussed. This model assigns each defect to a cluster. The distribution of cluster centers on a wafer is one basic component of the model. The other basic component is the distribution of defects (satellites) about the cluster centers. Physical justification for the model is provided. Current yield models are quite accurate for VLSI designs without redundancy. A more flexible model is needed to evaluate the redundancy technique… Show more
“…Although other models have been suggested (e.g., [69]), we will concentrate in this paper on this family of distributions due to the ease of calculation when using the Poisson distribution, the relative ease of the integration (analytical or numerical) needed for the compounding, and the documented good fit of these distributions to empirical data [17].…”
Section: A the Poisson And Compound Poisson Yield Modelsmentioning
“…Although other models have been suggested (e.g., [69]), we will concentrate in this paper on this family of distributions due to the ease of calculation when using the Poisson distribution, the relative ease of the integration (analytical or numerical) needed for the compounding, and the documented good fit of these distributions to empirical data [17].…”
Section: A the Poisson And Compound Poisson Yield Modelsmentioning
“…These Markov chains assume the defects "arrive" in a random order, so it is most relevant for repair algorithms that process one defect at a time and get their defects in random order (or are not harmed by ordering). This is the same technique as that used in [4]. Contrast this with the methods of [2,6], which rely, for example, on fault trees.…”
We give a Markov chain model of the yield of an embedded memory core. The model allows easy inclusion of the effect of possible defects elsewhere on the chip that includes the embedded memory. We propose a reconfiguration algorithm for the case of both spare rows and columns that is simple enough that it could serve as built-in self-repair on the chip. Compared to an optimal configuration algorithm, there is no visible difference in the yield. We use parameters from an IBM embedded SRAM process to illustrate the yield calculation. We study the effect of different spare allocations. We conclude that as long as there is at least one spare of each type, the spares do not need to be balanced, once the yield impact of being part of a system-on-a-chip has been taken into account.
“…Starting from (12), the second step of method A introduces the clustering effect that was not considered in the computation of Y r [by (11)]. λ r can be considered as the average number of faults left unrepaired after the first step; this is obtained by inverting the Poisson expression computed for k = 0, i.e., Y r = e −λ r .…”
Abstract-An accurate yield evaluation is essential in selecting redundancy allocation and testing strategies for memories. Yield evaluation can resolve the many issues revolving around costeffective built-in self-test (BIST) and automatic test equipment (ATE)-based solutions for a higher test transparency. In this paper, two yield-calculation methodologies for SRAM arrays are proposed. General yield expressions for VLSI chips are initially presented. The regular and repetitive structure of an SRAM array is exploited, and substantial yield improvements can be achieved by the introduction of redundancy. Two repair yield-evaluation methods for one-dimensional redundant memory arrays are introduced and compared for ATE application. The first method is based on the sum of the probabilities of all repairable fault patterns; the second method is based on Markov modeling. Using industrial data, it is shown that these methods are applicable to ATE usage under different conditions of defect rate in the possible defects. Different features of the proposed methods are discussed.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.