Abstract
A new self-converging programming characteristic in a single-poly floating-gate memory cell with full-compatibility to a CMOS logic technology is observed and studied. A uniquely design cell with a narrow-bridging line between two coupling capacitors promotes a localized charging effect at the electron tunneling site, leading to clamping of threshold voltage states. Through this mechanism, the new multi time programmable (MTP) cells exhibit tight threshold voltage distributions for multi-level cells (MLC) operations. Improved cycling reliability and one-shot multi-level programming has been fully demonstrated in this work.
Highlights
As the market demand for embedded memory grows, there are many solutions that serve different users meeting their various needs on versatile CMOS platforms
multi-level cells (MLC) [2]–[4] are one of the common and effective schemes to raise storage volume without changing the basic memory array hardware. This method has been extended to triple-level cell (TLC) and quadruple-level cell (QLC) technologies used in many commercial nonvolatile memory products [5]
To ensure MLC operation, writing of data generally requires going into a few program-verify iterations [14], which in-turn calls for extra circuits, e.g., error correcting code (ECC) [15] and redundancy [16]–[17], increase the overhead on peripheral circuits
Summary
As the market demand for embedded memory grows, there are many solutions that serve different users meeting their various needs on versatile CMOS platforms. MLC [2]–[4] are one of the common and effective schemes to raise storage volume without changing the basic memory array hardware This method has been extended to triple-level cell (TLC) and quadruple-level cell (QLC) technologies used in many commercial nonvolatile memory products [5]. When removing stored electrons from the FG, a localized charging effect was found, causing a transient saturation of the threshold voltage This unique feature is applied to the programming of multiplelevel storage on the narrow-bridge single-poly MTP cells. The newly discovered unique programming characteristics on these cells, fully-compatible to standard CMOS process, is studied for precise Vth level control in multi-level cell operations This cell with proper operation scheme provides an easier mechanism to obtained stable multi-level threshold voltage states. Lower power consumption and enhances programming efficiency can be obtained with a single-pulse operation as compared to the conventional MLC methods [23]–[25]
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