Optimization of Nitridation and Reoxidation Conditions for an EEPROM^* Tunneling Dielectric

Abstract

We show that the maximum reoxidation time is one of the useful parameters for determining the optimum processing condition of reoxidized nitrided oxide (RONO) film. The maximum reoxidation time is defined as the time in which the thickness of a nitrided oxide film increases 10%. Since many RONO process parameters have a close relationship to this parameter, it is easy to determine an optimum RONO condition. Using such an optimized condition of RONO film formation, that is, performing the nitridation of oxide in 50% NH3 ambient at 1050°C for 30 s and following it with reoxidation in O2 ambient at 1100°C for 120 s, we formed 9-nm-thick RONO film as the EEPROM tunnel dielectric. The film is found effective not only in improving the endurance to more than 106 cycles, but also in causing no degradation at all to the characteristics of the 1M-bit EEPROM devices actually fabricated.

Low-Temperature SiO[sub 2] Layers Deposited by Combination of ECR Plasma and Supersonic Silane/Helium Jet

“…A broad range of applications, including wafer postprocessing, 1 thin-film transistors ͑TFTs͒ for large displays, 2 and three-dimensional integrated circuits ͑3D ICs͒, such as stacked memory devices, 3 require very good dielectrics with excellent interfaces. 4 However, these applications constrain the thermal budgets to the processing temperature below 400-450°C. Such a low temperature generally leads to inferior film properties.…”