Articles

January 14,2021

Quantum Tunneling Mechanism in NeoFuse

NeoFuse is a logic-process compatible non-volatile memory (logic-NVM) using impedance change for data storage in one-time programming (OTP) applications. Storing data through NeoFuse can enable low-power operation, high reliability, and strong security. Using NeoFuse OTP IP as an embedded memory solution in a chip will provide user-friendly interface and fully integrated OTP IP that minimizes design effort and circuit complexity.

The NeoFuse OTP IP can be used for: (1) code storage, (2) identification or encryption data storage, (3) storage of timing, parameter setting, function selection, (4) and flexibility of field updates and product customization. Therefore, NeoFuse macros suits a wide range of applications, including set-top boxes, application processors, digital TVs, CMOS imaging sensors, baseband processors, LCD drivers, power management ICs and more.

The judgement on data “0” or data “1” relies on the gate conduction current level of a core nFET within the NeoFuse cell. The initial state of a NeoFuse bit-cell shows high impedance in the gate oxide because the trap density of the gate oxide is extreme low. To write data, the impedance of the gate oxide can be changed through programming with a well-chosen gate bias. After programming, the gate conduction current will significantly increase. The sensing amplifier in the NeoFuse macro can distinguish whether the memory bit stays at data “1” or data “0”.

To generate a high gate conduction current in a thick-oxide FET, a percolation path must be created under the high gate electric field for the gate current to move through this percolation path. However, the conducting mechanism in ultra-thin gate oxide is quite different. The main conducting mechanism is quantum tunneling in the ultra-thin gate oxide.

Classic mechanics predict that particles with insufficient energy cannot surmount an energy barrier. However, a proportion of particles can actually penetrate an energy barrier even if all particles do not have enough energy. Quantum mechanics predict a non-zero probability of a particle to be on the other side of the energy barrier because every particle has wave-particle duality in nanoscale or quantum-scale....More