K. Koh

Plasma-assisted formation of low defect density SiC–SiO2 interfaces

The initial stages of SiC–SiO2 interface formation by low temperature (300 °C) remote plasma assisted oxidation (RPAO) on flat and vicinal 6H SiC(0001) wafers with Si faces have been studied by on-line Auger electron spectroscopy (AES). Changes in AES spectral features associated with Si–C and Si–O bonds are readily evident as oxidation progresses; however, there are no detectable AES features that can be attributed to C–O bonds. Initial oxidation rates as determined from AES data are greater for vicinal wafers than for flat wafers paralleling results for RPAO oxidation of Si. Devices fabricated on vicinal SiC wafers require an 1150 °C anneal in an H2 containing ambient to reduce defect densities from the 1013 to 1011 cm−2 range, consistent with termination of C atom step edge dangling bonds by H atoms. Devices prepared by thermal oxidation also require a 1150 °C anneal in H2 even though silicon oxycarbide regions with C–O bonds are formed in a transition region at the SiC–SiO2 interfaces.

ULTRA-THIN GATE DIELECTRICS PREPARED BY LOW-TEMPERATURE REMOTE PLASMA-ASSISTED OXIDATION

Abstract This paper discusses the formation of ultra-thin nitrided gate oxides by a low temperature plasma assisted oxidation process using remotely excited N2O as the source gas for both oxygen and nitrogen atoms. Three aspects of this process are addressed: (i) the differences in oxide growth rates for O2 or N2O plasma oxidation processes; (ii) the reaction pathways for the incorporation of nitrogen at the SiSiO2 interface for the N2O plasma process; and (iii) possible nitrogen atom depletion during processing steps that follow the plasma assisted oxidation/nitridation process.

Plasma-engineered Si-SiO2 interfaces : monolayer nitrogen atom incorporation by low-temperature remote plasma-assisted oxidation in N2O

Abstract This paper presents experimental studies in which N-atoms have been incorporated at Si−SiO 2 interfaces by forming the interface and oxide film by a 300 °C remote plasma-assisted nitridation/oxidation process using N 2 O. Process dynamics have been studied by interrupted plasma processing using on-line Auger electron spectroscopy (AES). Based on the on-line AES, and complementary ex situ secondary ion mass spectroscopy and optical second harmonic generation results, monolayer nitrogen atom interface coverage has been confirmed. The factors that contribute to preferential nitrogen atom attachment at the Si−SiO 2 interface have been identified.

Controlled Nitrogen Incorporation at Si-SiO2 Interfaces by Remote Plasma-Assisted Processing.

This paper presents experimental studies in which N-atoms have been incorporated at Si–SiO2 interfaces by forming the interface and oxide film by a 300°C remote plasma assisted nitridation/oxidation process using N2O. Process dynamics have been studied by on-line Auger electron spectroscopy (AES) by interrupted plasma processing. Based on AES studies using N2O, O2 and sequenced N2O and O2 source gases, reaction pathways for i) N-atom incorporation at and/or ii) removal from buried Si–SiO2 interfaces have been identified, and contrasted with reaction pathways for nitridation using conventional furnace processing.

Improvement of Cell Stability at Low Voltage Operation on 6T-SRAM Cell with 0.1μm Channel Width

Cell stability at low voltage operation has been investigated with fully manufactured 0.1μm channel width 6T-SRAM cell. Increasing the channel width ratio of driver to access transistor, which is typical method to enhance the static noise margin (SNM), is no longer effective in sub0.1μm regime, because low voltage SNM is deteriorated due to inverse narrow width effect (INWE). To overcome the effect, the higher threshold voltages of cell nMOSFETs (driver and access) were effective for SNM improvement, but its method was limited by read current reduction, combined with narrow sensing margin. With separated Vth adjustment process, cell stability was improved by recovered SNM as well as read current.