PowerPoint Presentation

Updates of Iowa State University S. Dumpala, S. Broderick and K. Rajan

Oct-22, 2013 Summary Comparison of plasma and thermal oxidation with hyperthermal oxidation

Literature review on sub oxide species analysis for thermal oxidation of silicon and comparison with APT results

FIM Attempts

Plasma OxidationThermal OxidationThe concentrations of Si+1 (Si2O), Si+2 (SiO) in the interfacial region II and concentration of Si4+ (SiO2) in the bulk region III for the plasma oxidation match with hyperthermal one.

In the thermal case, the concentration of Si4+ (SiO2) in region III is much lower.

In thermal oxidation regime, the oxide thickness remains constant and is equal to native-oxide thickness- U. Khalilov et.al. - The observed trend is in agreement with no significant increase of Si4+

ReaxFF Simulation

Si+4Hyper thermal, Plasma and Thermal OxidationSub Oxide Species - Thermal OxidationTheoretical work demonstrated the role of sub oxide species on electronic properties (band gap profiles) of interface and leakage currents [1] [1]. B.H. Kim, et.al. J. App.Phys., 113, 2013

Theoretical models shown that sub stoichiometry effects phonon frequency shifts (Transverse optical, Longitudinal optical) apart from the compressive stress factor [2,3]. [2]. A. Roy, et.al. Phys. Rev B, 67, 2003 [3]. H. Ono, . J. App.Phys., 84, 1998

Studies of SiOx Thermal Oxidation

Synchrotron radiation photoemissionspectroscopy (PES) studies showed thatamounts of Si+2, Si+3 increases with T (700 1000 C), while Si+1 remains constant [4].[4]. Z.H. Lu, J. Vac. Sci. Technol. B., 13(4), 1995

This is attributed to structural relaxation to relieve long-range uniaxial strain (thermodynamic factor)

Another model predicts the change of distribution of sub stoichiometry near interface with increasing T from 550 to 700 C, and also predicts that sub oxide rich layer at higher temperature to be thicker [2]Significance of SiOx

Effect of Temperature on Growth Mechanism

APT results experimentally prove the increase in the interfacial width and change of sub oxide distribution and growth mechanism that agree with ReaxFF simulations

Thermal oxidation Vs Hyperthermal and Plasma oxidation (change of concentration of SiOx, and range of temperature)

Schematic FIM images of 110-oriented hemisphericaltip (radius 8nm) subjected to field evaporation (image-force model without polarization component) at 77K [1] Field Ion Microscopy (FIM)Preliminary attempts of FIM experiments were conducted using Tungsten tip Experimental resultSchematic ImageExperimental image of 110-oriented hemisphericaltip subjected to field evaporation (image-force model without polarization component) at 30 K using Ne gasChallengesThe temperature of stage and image quality

Software and equipment related issues Attempts of FIM on Si tips of Maryland

Initial results were obtained, but could not collect enough data

Tips tried studying were fractured

Images need to be analyzed

Bare Si need to be studied to estimate the damage250 V Ar bombarded 50 Monolayer Sample (Video clip of FIM Acquisition) FuturePlan to acquire better FIM images and analyze the results

Oxidation of Si paper is being written up Tentative Title : Effect of growth temperature on oxidation of Si and interfacial sub oxide species analysis via Atom Probe Tomography

New Aluminum needles for Ar bombardment studies for Jarred are being ordered

Simulation results of Ar bombardment effects on Aluminum