Research And Design Of Flash Memory Used For DSP

The research and production of Flash memory have reached a mature stage, but with the rapid development of semiconductor and microelectronic industry, the design and production of Flash memory still faces many challenges, for instance, the limitation of device size reduction, as well as the conflicts between voltage, power consumption and programming speed. Flash memory design has become one of the most challenging directions in the field of semiconductor technology, especially in the design field of microprocessor, such as DSP.With the application of digital signal processor and memory continue to expand, Flash memory design is facing new challenges such as the stability and reliability in extreme conditions, or, the antiradiation performance in space environment or high energy physics experiment and so on. Under such background, a novel 1M bit Flash memory is presented in this paper. The proposed Flash memory satisfies design requirements of high reliability in extreme conditions, and achieves radiation-resistant performance under radiation dosage unit of 50K rad (Si).In this paper, first, based on the cell characteristic and design requirements, the array and system architecture, as well as the parameter setting and module division of Flash memory are presented. Further, for the radiation-resistant performance of 50K rad(Si), modified designs for the memory cell and peripheral circuits with the ability of antiradiation are proposed. For the storage cell design, the design scheme that both the memory cell and the NMOS select transistor are improved by the gate-all-round structure is chosen after a comprehensive analysis of the mechanism of radiation damage on MOSFET. For peripheral circuits design, the designs of devices and circuit units, which are vulnerable to the radiation effects, are improved by radiation hardening techniques. Furthermore, the bandgap voltage reference module and sense amplifier module are optimized. Under radiation condition of 50K rad (Si), the failure of positive charge pump is considered as the main factor that causes the malfunction of the non-volatile memory. To solve this problem, a novel ZMOS positive charge pump, which is radiation-resistant, is proposed. Peripheral circuits design also includes the hamming code error correction circuit, which can detect and correct the error code, and improve the stability of the memory circuit.Followed the circuit design, the layout and post-simulation of circuits is analyzed and completed.The results show that the voltage, power and speed of the proposed 1M bit Flash memory meet the design requirements, while the important parts of the memory being improved by radiation hardening techniques. The proposed memory has a wide range of application potentials.