Effect Of Device Reliability On Memory Reliability

Two important factors in the design of a memory for a computer with a long life expectancy are: the reliability of the parts comprising the system and type of reliability enhancement technique selected. The most significant conclusion of this paper is that memory system reliability is extremely sensitive to memory IC failure rate, λ For the memory system example, λ must be approximately 10-7 failures/hour for the system to have a useful life expectancy. If λ is appreciably less than 10_-7 then little or no protection is required to achieve the design goals. On the other hand, if the failure rate is appreciably greater than 10_-7, then the design goals cannot be achieved no matter which technique is selected. Apparently, the underlying factor is the reliability per function. This quantity improves as the level of integration increases since chip reliability is relatively insensitive to chip density.