Ultra-low-temperature growth of high-integrity gate oxide films by low-energy ion-assisted oxidation

Abstract

The gate oxide films have been grown at a temperature as low as 450 °C by direct oxidation of silicon. Such a low-temperature oxidation has been realized by employing a precision controlled ion bombardment in an Ar/O2 mixed plasma for the surface activation. Perfectly controlled Ar ions give the bombardment energy for the oxide film growth. Dielectric breakdown fields of 10 MV/cm are achieved. Integration in a total low-temperature device process has been demonstrated by fabricating self-aligned Al-gate metal-oxide-silicon field effect transistor (MOSFET) formed without any heat processing over 450 °C. The precise control of the ion bombardment is quite essential for the low-temperature process.

Plasma-assisted oxidation, anodization, and nitridation of silicon

“…At a lateral distance >0.5 cm from the needle center projection on the wafer, the oxide thickness was essentially that obtained with a thermal oxidation process of equal time. With a positive needle potential [34], less enhancement occurred than in the thermal oxidation case; the thickest oxide (-70% thicker than thermal) was observed at a lateral distance of -1 cm from the needle center. Although the transport of oxygen ions (probably O ) is an important factor in explaining the "needle negative" results, an explanation for the results observed with the needle positive is currently lacking [35].…”

“…A dual-frequency parallel-plate reactor with a magnetically enhanced upper electrode operating at 100 MHz and a lower (substrate) electrode operating at 41 MHz has been used to oxidize silicon at temperatures between 100° and 450°C with 2.6% O^ in argon [34]. The power supplied to the lower electrode (2 W) established low energy (~15 eV) argon ion bombardment in order to "assist" the low-temperature oxidation.…”

High-intensity oxygen cluster ion beam generation and its application to cluster ion-assisted deposition

“…Energetic beams are quite useful for achieving low-temperature oxidation processing due to their excess kinetic energy [14][15][16]. We have demonstrated direct oxidation of silicon surfaces at room temperature with a low-energy oxygen cluster ion [3,5] and also PbO 2 film formation under oxygen cluster ion irradiation during Pb evaporation [10].…”

Effects of thickness and rf plasma oxidizing on structural and optical properties of SiOxNy thin films

“…Rf plasmas in oxygen or oxygen containing plasmas have wide applications in material processing such as photo resist etching, chemical vapor deposition, and oxidation. Other technologies include for example thin oxide growth at low temperature for the fabrication of gate oxide of thin film transistors [15]. The great majority of fundamental studies involve the interaction between oxygen plasma species and solid surfaces, but there is a lack of specific correlation between optical properties and plasma parameters.…”