BIST(Built-in self test) is to detect various faults of the existing memory and BIRA(Built-in redundancy analysis) is to repair detected faults by allotting spare. Also, BISR(Built-in self repair) which integrates BIST with BIRA, can enhance the whole memory's yield. However, the previous methods were suggested for RAM and are difficult to diagnose disturbance that is NAND-type flash memory's intrinsic fault when used for the NAND-type flash memory with different characteristics from RAM's memory structure. Therefore, this paper suggests a BISD(Built-in self diagnosis) to detect disturbance occurring in the NAND-type flash memory and to diagnose the location of fault, and BISR to repair faulty blocks.

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It has been an increase in consumers who want a high-capacity and fast speed by the newly diffused mobile device(Smart phones, Ultra books, Tablet PC). As a result, the demand for Flash Memory is constantly increasing. Flash Memory is separated by a NAND-type and NOR-type. NAND-type Flash Memory speed is slow, but price is cheaper than the NOR-type Flash Memory. For this reason, NAND-type Flash Memory is widely used in the mobile market. So Fault Detection is very important for Flash Memory Test. In this paper, Proposed PMBIST for Pattern Test of NAND-type Flash Memory improved Fault detection.

As cell size shrinks in NAND Flash memory, assuring adequate reliability characteristics is getting difficult due to the sensitivity of Flash cell against small process changes. Especially, it is still unclear how the combination of mechanical stresses encapsulating the cell structure affects the reliability characteristics. In this paper, we present our results on how to improve reliability with optimizing mechanical stress in active and interpoly dielectrics (IPD) thickness, and confirmed the results through various simulations and test methods on 41nm NAND technology. Hereafter, we need to fully confirm the ISO and IPD beyond 3x nm technology node.