Effects of humidity on nano-oxidation of silicon nitride thin film

Humidity- tunable liquefaction of Cr thin-film and its application to patterning

Electric field induced liquefaction of chromium (Cr) thin-films, being a surface-based process, is affected by the moisture content in the surroundings. The said process is an electrochemical reaction, which takes place on an electrically stressed Cr thin-film. The reaction results in a liquid region, which appears to flow out radially from the tip of the cathode. A proper understanding of the phenomenon is warranted as it is applied for performing a nanolithography process, electrolithography (ELG). In this study we have focused on the effect of relative humidity (RH) on the material formation and transport on electrically stressed Cr thin-film. Varying the RH over a wide range, the phenomenon is studied using different levels of DC stress. The effect of the applied DC stress coupled with varying levels of RH showed trends which are explained qualitatively and quantitatively. The results indicate that RH could be a pivotal parameter affecting the above-mentioned phenomenon on electrically stressed Cr thin-films and could significantly alter the minimum feature size attainable by ELG. To demonstrate the effect of RH on ELG, lines are drawn at various humidity levels resulting in greater than 100% increase in the attainable line width when RH is increased by about 40%.

Impact of parameter variation in fabrication of nanostructure by atomic force microscopy nanolithography

In this letter, we investigate the fabrication of Silicon nanostructure patterned on lightly doped (10¹⁵ cm⁻³) p-type silicon-on-insulator by atomic force microscope nanolithography technique. The local anodic oxidation followed by two wet etching steps, potassium hydroxide etching for silicon removal and hydrofluoric etching for oxide removal, are implemented to reach the structures. The impact of contributing parameters in oxidation such as tip materials, applying voltage on the tip, relative humidity and exposure time are studied. The effect of the etchant concentration (10% to 30% wt) of potassium hydroxide and its mixture with isopropyl alcohol (10%vol. IPA ) at different temperatures on silicon surface are expressed. For different KOH concentrations, the effect of etching with the IPA admixture and the effect of the immersing time in the etching process on the structure are investigated. The etching processes are accurately optimized by 30%wt. KOH +10%vol. IPA in appropriate time, temperature, and humidity.

INFLUENCE OF ROOM HUMIDITY ON THE FORMATION OF NANOSCALE SILICON OXIDE PATTERNED BY AFM LITHOGRAPHY

Nanometer-scale silicon oxide mask was patterned by atomic force microscope (AFM) lithography for fabrication of nanoelectronic devices. The oxide growth mechanism is similar to a well-known local anodic oxidation, which a negative voltage applied to conductive AFM tip in order to grow oxide patterns on silicon layer surface. The surrounding environment is one of the very important parameter on the formation of nanoscale silicon oxide patterns via AFM lithography. Therefore, in this work, the effect of relative humidity (RH) has been studied systematically in the range of 55–72%. Meanwhile, the applied tip voltage, exposure time, and scanning speed were kept constant during lithography process. From AFM topographic analysis on the fabricated nanopatterns found that the oxide width and thickness are significantly depending on the room humidity. These results proved that the room humidity is playing an important role on the fabrication of nanometer-scale oxide patterns by using AFM nanolithography.

Electro-oxidative nanopatterning of silane monolayers on boron-doped diamond electrodes

Oxidized boron-doped diamond (BDD) electrodes were coated with a monolayer of n-octadecyltrichlorosilane as well as of other silanes. Scanning force microscopy was applied to pattern these monolayers, utilizing doped diamond-coated conductive probes. Patterns were generated on the nanometer scale, and conditions for the patterning process were quantified with regard to humidity and potential bias. It was observed that a sample bias of 3-3.5 V and a relative humidity >70% are necessary to generate reproducible and stable patterns. At potentials and relative humidities below these values, no or incomplete removal of the monolayer occurred. The results show that electro-oxidative patterning is an expedient way for the generation of nanostructures on chemically modified BDD.