1. Basic Concepts in Reliability Design - nl3prc

[2] Designing for Reliability2.4 Factor Analysis TechniquesIn general, the analysis of reliability factors during product design and process design is very effectivefor improving reliability. The main reliability factor analysis techniques are:(1) Design Review (DR)(2) Fault Tree Analysis (FTA)(3) Failure Mode and Effect Analysis (FMEA)DR, in the case of semiconductor devices, means verifying the items shown in Table 2.1 and correctingany problems so as to yield a more robust product. Normally, a design standard is defined to simplifyand guide this process. Design thus proceeds according to the standard and the design is checkedagainst the standard during the DR. If there are any deviations, tests are run to confirm adherence tothe standard and the standard is updated as necessary.FTA analyzes factors contributing to device failure, such as circuit configuration, pattern design,manufacturing process, package design and operation method.The analysis divides the design, manufacturing, packaging and operation phases into well-defineddetailed functional items. The possible failure modes and the effects of such failures are known foreach item. These items are then weighted so that countermeasure priorities can be defined andestablished.An example of the FMEA method is shown in Table 2.6 for a plastic-package MOS LSI manufacturingprocess. Using a scale of 1 to 10, the Failure Index section of the table rates failure information interms of frequency, effect (on the product, equipment or system) and detectability. A failure index iscalculated by multiplying these three rated values together. The larger the index value, the moreserious the failure.The last column in Table 2.6 shows countermeasures for each process-related failure.2-8