Characteristics of tunneling nitride grown by electron cyclotron resonance nitrogen-plasma nitridation and its application to low-voltage electrical erasable-programmable read-only memory

Abstract

Characteristics of a tunneling-nitride insulator grown by low-temperature electron cyclotron resonance (ECR) nitrogen-plasma nitridation are presented. The ECR nitridation shows a very high growth rate at lower temperatures and the thickness is proportional to the growth time. For example, we obtain a thickness of 16 [nm] and a refractive index of 1.75 after the nitridation time of 80 [min] at 400 degreesC. The barrier heights measured from the Fowler-Nordheim (F-N) tunneling current are 2.3 [eV] and 1.4 [eV] in the inversion and the accumulation modes, respectively. These lower heights allow us much faster programming and erasing times of an electrical erasable-programmable read-only memory (EEPROM) with the ECR nitride than those of the conventional EEPROM with the thermal oxide. A double-gate EEPROM with an ECR-nitride tunneling insulator was fabricated. Surprisingly, it does not show any threshold voltage (V-TH) degradation even after 100,000 cycles of programming and erasing.