Clarification of Nitridation Effect on Oxide Formation Methods

Abstract

The electrical characteristics of gate dielectrics have been intensively studied. We examined four types of gate dielectrics: thermal oxide films formed in a pyrogenic steam ambient, those in a dry oxygen ambient, chemical vapor deposition (CVD) oxide films, and the thermal/CVD stacked oxide films. The effects of nitridation on oxide properties have been also systematically investigated using the nitrogen implantation technique. It is found that hot-carrier degradation can be improved by nitridation irrespective of the oxidation methods. This improvement is attributed to the suppression of interface state generation and the reduction in the number of electron traps in the oxide films. Our extensive investigation concludes that the nitridation of gate oxide films by nitrogen implantation is very promising for the improvement in reliability in spite of the difference in oxide formation methods.

Effects of the surface deposition of nitrogen on the thermal oxidation of silicon in O2

“…[1][2][3] In particular, the thermal oxidation in O 2 of Si wafers previously implanted with N ions has been considered recently as a route to prepare silicon oxynitride films for gate dielectrics in ultralarge scale integrated ͑ULSI͒ metal-oxide semiconductor field effect transistor ͑MOSFET͒ devices. [4][5][6][7] It has been known for a long time that the presence of rather small concentrations of N ͑1 at % and less͒ slows down the thermal oxide ͑oxynitride͒ growth in O 2 . 8 The effect of N implantation doses below and around the equivalent to 1 monolayer in reducing the rate of thermal growth of SiO 2 in dry O 2 has been reported previously.…”

Ultrathin silicon oxynitride film formation by plasma immersion nitrogen implantation

“…[3][4][5][6][7] Further, ion implantation can result in oxynitrides with higher N concentration than the aforementioned thermal processes.…”

Growth of ultrathin oxides of silicon by wet oxidation at very low (0.04 atm) water vapour pressure

“…Growth of these ultrathin oxides with good thickness uniformity and high electrical quality imposes stringent demands on oxidation techniques. Even though there are several reports regarding the superior quality of the wet oxide over dry oxide process [1][2][3][4][5][6][7][8], the dry oxidation process has been the main candidate for the growth of ultrathin oxides of silicon for gate oxide applications. So far, wet oxidation has not been considered for gate and tunnel oxide applications for the following reasons; (i) high growth rate associated with conventional wet oxidation (at 1 atm water vapour pressure) and (ii) the large density of electron trapping centres present in the wet oxide.…”