Retention testing of MNOS LSI memories

User-oriented test methods for MNOS LSI memories with built-in test modes have been developed. Their application is demonstrated on the commercial ER3401 memory. The memory retention is evaluated in two cases-the static retention time in power-down or in stand-by and the read retention during repeated reading, i.e., the maximum number of read cycles. In the first case, the two loss mechanisms, tunneling and thermal excitation of stored charge are evaluated separately and their influence is combined. In the second case, the limiting mechanism is slow writing by the read signal. On bases of these investigations, a static retention time of 60 yr at 70°C and 2 yr at 125°C is predicted and a read retention of 3×10/SUP 11/ read cycles at 70°C and 2×10/SUP 9/ cycles at 125°C is found for the ER3401.