Abstract
Compared with n-channel Flash memory, P-channel Flash memory features such advantages as low voltage operation, low power consumption, better scaling capability and hot-hole injection free operation. However, disadvantages of small read current and serious drain disturbance limit its application. Therefore, in this study an Enhanced Band-to-band Tunneling programming P-channel Flash memory ( EBTP ) is proposed, with three main advantages of enhanced programming gate current and speed, enhanced read current, and smart control over the programmed threshold voltage. This is because a parasitic NPN bipolar transistor structure is included in the drain side of the EBTP cell. On the one hand, the hole current initiated by the band-to-band tunneling process serves as the base current of the drain-side parasitic NPN bipolar transistor, and thus an active operation mode is ensured. Indeed, this mode of operation forms a novel programming mechanism. On the other hand, the concept of enhanced read operation due to the parasitic NPN bipolar transistor is also employed from prior art to our device. In this way, a double performance enhancement is achieved in our device operation. Moreover, the enhanced programming drain current is incorporated with proper circuitry to control the distribution of the programmed threshold voltage. With the high speed and smart controlling mechanism of the programming operation, a drawback of high power consumption during programming can be avoided. Finally, the optimized process designed for the scaling of EBTP cell and designing guidelines based on operation performance are summarized in our study. From the aforementioned performance enhancement, EBTP Flash memory cell provides solutions to the limitations of concurrent p-channel Flash memory, demonstrating its potential in high speed and high density application.