微电子系统的可靠性分析

Summary—Life test data were obtained on the UTMC Microelectronic Systems 64K and 256KBit programmable
read-only memories (PROMs) following post-program conditioning (PPC). PPC is used to enhance the reliability
(and radiation tolerance) of the UTMC PROMs following programming. To date, the life-test data show a mean
time to failure (MTTF) for the 64K PROM of 1,476 years and a MTTF of 369 years for the 256K PROM (using a
60% confidence limit at 55°C). Data collection is continuing and updated reliability numbers will be published, as
they become available.
Introduction
The UTMC Microelectronic Systems (UTMC) 64K and 256K programmable read-only memory (PROM) uses an
amorphous silicon (a-Si) based antifuse. In the unprogrammed state the antifuse has a high resistance, typically
>109W. Following programming with a series of voltage pulses, a low resistance filament is created. The UTMC
PROMs use a 2-transistor/2-antifuse structure for each cell. Following programming, each cell has one
programmed (low-resistance) antifuse and one unprogrammed (high-resistance) antifuse. For reliable operation,
therefore, the programmed antifuse must stay in a low resistance state and the unprogrammed antifuse must stay in
a high resistance state for the life of the product.