| dc.description.abstract | With the development of Artificial Intelligence (AI), the emphasis on large memory capacity and low-power consumption has become the mainstream of chip design. In order to achieve high memory capacity and low-power consumption, NAND FLASH is the mainstream of non-volatile memory because of its low cost and low-power consumption, but its read and write speed is slower. With the rapid development of the emerging memory technologies recently, the RRAM has faster read and write capability and reliability , compared to NAND Flash memory. Therefore, the RRAM becomes the most promising candidate in terms of its smaller size, low-power consumption and simple manufacturing process.
In this thesis, we have proposed a multi-bit-storage technology using the RRAM 1-transistorand 1-RRAM array. The 1 transistor (T) in 1T1R is a control transistor to control access of the RRAM cell, and the 1 RRAM (R) is a metal-insulator-metal (MIM) structure. The use of continuous linear gradual tuning scheme to operating the SET and RESET operation can effectively extend the the memory window. The designed RRAM can achieve multi-bit storage in both low resistance states (LRS) and high resistance states (HRS). The multi-bit storage method is advantageous to realize the operation of Ternary Content Addressable Memories (TCAM) because the TCAM stores three states, including the logic “1”, the logic “0” and the “don’t care” state. We define the LRS as the logic “1” and the HRS as the logic “0”.As a result, we need to find a stable resistive state between the LRS and HRS to define the “don’t care” state to realize the operation of the TCAM.
In comparison of the traditional the SRAM-based TCAM, the size of the RRAM-based one is much smaller . The RRAM array with a capacity of 1Mb1-Mb with an unit area of 0.0079 um2, and the difference of the memory window between the low-resistance state and high-resistance state can be up to near 200 times. As far as the multi-bit storage performance is concerned, there are 10 states in the low-resistance states and 15 states in the high-resistance states, leading to total 25 states, which can effectively improve the storage density of the 1T1R RRAM array. With the further development and maturity of the mult-bit-storage 1T1R RRAM technology, RRAM-based TCAM may have a greater advantage in future in-memory-searching applications. | en_US |