Rapid Thermal Oxidation Process Research Articles

Formation of HfOxNy nanorod GLAD films growth by rapid thermal oxidation

In this work, the hafnium oxynitride (HfON) nanorod films on p-type silicon (Si) wafer substrate have been fabricated by reactive magnetron sputtering with glancing angle deposition (GLAD) technique, subsequently with a rapid thermal oxidation process at 500–900 °C under low-vacuum state. The crystallinity and morphology were investigated by glazing-incident X-ray diffraction (GIXRD) and field-emission scanning electron microscopy (FE-SEM), respectively. As-deposited films were amorphous nanorod films. The surface-sensitive X-ray photoelectron spectroscopy (XPS) analytical technique revealed that nitrogen atoms are increasingly replaced with oxygen atoms at the surface. The distribution of nitrogen atoms investigated by X-ray absorption spectroscopy (XAS) revealed the substitution of nitrogen with oxygen at the film surface and molecular nitrogen trapped in the film as the annealing temperature was increased.

Porous Silicon on Insulator Technology

In this research, the structure, optical, and electrical properties of porous silicon prepared by electrochemical etching at current density 50 mA /cm2 with etching time 10 min, before and after rapid thermal oxidation process (RTO) at different oxidation temperature from (500-700) Ċ and constant oxidation time 60 s. Under optimum conditions, the pore size decreased after RTO leads to decrease porosity, the refractive index decreased for porous silicon (PS) and increased after oxidation. Electrical properties were showed an increase in rectification ratio after oxidation, where it varied from (3.93 to 158.8), the ideality factor which describes an approach the device from ideality characteristics founded decrease with increasing oxidation temperature where it varied from (9 to 5.4), the barrier height increased from (0.561 to 0.698 eV). The oxidation process improves electrical conductivity for electronic device by decreasing saturation current density that initiated from minority carriers, where (OPS/PS/Si) work as anti-reflected coating that benefit to eliminate swings effect and standing waves in photoresist.

Optimization of Bump Defect at High-Concentration In-Situ Phosphorus Doped Polysilicon/TEOS Oxide Interface for 3D NAND Flash Memory Application

In the 3D NAND Flash memory manufacturing process, high-concentration in-situ phosphorus-doped polysilicon and TEOS oxide stack will produce bump defects at the interfaces, causing pattern defects and electrical failures. The formation mechanism of bump defects caused by oxygen-containing groups and phosphorus at the lower and upper interfaces of phosphorus-doped polysilicon is investigated in detail. Two methods were demonstrated to reduce bump defects, wet processing and Rapid Thermal Oxidation (RTO). The wet processing is to remove oxygen-containing groups and phosphorus, while the RTO process increases the solubility of phosphorus in silicon. Both methods have significantly reduced bump defects and greatly increased the yield rate, and further verify the proposed formation mechanism of bump defects.

Large enhancement of ultra-violet photoresponse of silicon-nanoparticle-embedded porous silicon thin films by rapid-thermal-oxidation treatment

The ultra-violet (UV) photoresponses of silicon-nanoparticle-embedded porous silicon thin films that were prepared from electrochemical-etching silicon substrates in an anodization process had been greatly enhanced by rapid-thermal-oxidation (RTO) treatment. Experimental analysis demonstrated that the optical bandgap energy of the formed nanoporous silicon (NPS) films increased from 1.6eV to 3.5eV after the RTO process. It was supposed that this bandgap-widening effect resulted from the size shrinking of Si-nanocrystals embedded in the oxidized NPS films and led to the large increase in UV responses. With RTO treatment of 90s, the oxidized NPS films exhibited high UV photoresponses for incident light of wavelength between 300nm and 400nm, with peak photoresponsivity of 78mA/W at 375nm. In addition, under illumination of 350-nm UV light, the photodiode based on these RTO-treated NPS films got a 370-time larger photo-to-dark current ratio (PTDR) than that of one fabricated without RTO treatment. Therefore, oxidized NPS materials prepared by RTO treatment after the electrochemical-etching of Si wafers have high potential for development of Si-based UV photodetectors.

Effects of HfO2/SiON/SiN stacked trapping layer on operation characteristics of poly-Si flash memory devices

A HfO2/SiON/SiN (HON) bandgap-engineered trapping layer (BETL) on inversion-mode (IM) and junctionless (JL) polycrystalline-Si flash memory devices is investigated in this work. The HON layer is formed by performing a rapid thermal oxidation process between the depositions of SiN and HfO2. For IM device, the programming speed, retention and endurance characteristics are improved by the HON BETL while without degrading its erasing speed when compared to that with HfO2/SiN (HN) BETL. As to the JL device, improved erasing speed and retention characteristics are obtained with HON BETL; high programming speed and good endurance performances of the JL device are also observed. HON BETL is promising to improve retention characteristics of poly-Si flash memory devices since the conduction band level of SiON is higher and the trap density of SiON is lower as compared to those of SiN.

Rapid thermal oxidation of zinc nitride film

In this work, a zinc nitride (ZnN) film was deposited at room temperature and subjected to pulse-mode rapid thermal oxidation. The physical and chemical structures of ZnN film were changed during the rapid thermal oxidation process. The presence of zinc-oxygen bonds in the oxidized ZnN film indicated that some nitrogen atoms within the ZnN film are replaced by oxygen atoms. Through the rapid thermal oxidation process, ZnN was converted into a zinc oxide material containing nitrogen atoms. The oxidized ZnN possessed more acceptor states than donor states, which resulted in p-type conduction. The carrier concentration, mobility, and resistivity of the rapid-thermal-oxidized ZnN were 6.49 × 1018 cm−3, 12.9 cm2 V−1 s−1 and 0.7 Ω cm, respectively.

Rapid Thermal Oxidation of Si-Face N and P-Type On-Axis 4H-SiC

This paper deals with the comparison of several MOS structures with different rapid thermal oxidation processes (RTO) carried out on Off and On-axis SiC material. A first set contains MOS capacitance structures on n-epitaxial layers, while a second set of MOS capacitance are built on p-implanted layers. Both sets include On and Off-Axis angle cuts. Furthermore, n-MOSFETs have been fabricated on On-axis p-implanted layers with the best oxidation process selected from the MOS capacitance study. The final objective is to show the performances of these On-axis p-implanted n-MOSFETs and to evidence the associated lower surface roughness at the SiO2/SiC interface.

Nanoscale electrical and structural modification induced by rapid thermal oxidation of AlGaN/GaN heterostructures

In this paper, the structural and electrical modifications induced, in the nanoscale, by a rapid thermal oxidation process on AlGaN/GaN heterostructures, are investigated. A local rapid oxidation (900 ° C in O2, 10 min) localized under the anode region of an AlGaN/GaN diode enabled a reduction of the leakage current with respect to a standard Schottky contact. The insulating properties of the near-surface oxidized layer were probed by a nanoscale electrical characterization using scanning probe microscopy techniques. The structural characterization indicated the formation of a thin uniform oxide layer on the surface, with preferential oxidation paths along V-shaped defects penetrating through the AlGaN/GaN interface. The oxidation process resulted in an expansion of the lattice parameters due to the incorporation of oxygen atoms, accompanied by an increase of the crystal mosaicity. As a consequence, a decrease of the sheet carrier density of the two-dimensional electron gas and a positive shift of the threshold voltage are observed. The results provide useful insights for a possible future integration of rapid oxidation processes during GaN device fabrication.

SURFACE MORPHOLOGY AND X-RAY DIFFRACTION ANALYSIS FOR SILICON NANOCRYSTAL-BASED HETEROSTRUCTURES

In this work, we studied the effect of rapid thermal oxidation process on the structural and surface morphology of silicon nanocrystal-based heterostructures. PLD technique was employed in combination with rapid thermal oxidation process to form multilayers heterostructures. Results show the dependence of the surface roughness and structure on the oxidation temperature. Best surface morphology was achieved at 723 K oxidation temperature, at which, the X-ray diffraction result ensured the formation of the Cu 2 O phase at (111) and (002) diffraction plain with uniform porous surface.

Characteristics of Nanostructure Silicon Photodiode using Laser Assisted Etching

Abstract We prepared nanostructures silicon photodiode (nPSi) by using laser assisted etching at fixed current density (30 mA/cm2) with different etching wavelengths of laser diode (532,650 and 810 nm), a (metal/nanostructure silicon/metal) photodiode has been fabricated from rapid thermal oxidation (RTO) and rapid thermal annealing (RTA) processes to improve the characterizations of PSi photodiode, A responsivity of (3A/w) was measured at (450 nm) with low value of dark current (1.33 μA/ cm) and higher value of photo current (610 μA/cm 2 ) at 5 volt reverse bias. The results show that the wavelength IR (810 nm) give us the best photodiode and electrical characteristics.

Facile fabrication of cuprous oxide nanocomposite anode films for flexible Li-ion batteries via thermal oxidation

In the present work, nanostructured Cu2O films are directly grown from a Cu metal foil by means of a rapid thermal oxidation process. The structural characteristics of the films are investigated by field emission scanning electron microscopy, X-ray diffraction and attenuated total reflectance Fourier-transformed infrared spectroscopy. The electrochemical behaviour is investigated in both lithium (liquid electrolyte) and all-solid lithium polymer cells. At a discharge/charge rate of C/5, the films can provide a specific capacity greater than 220 mAh g-1 in the all-solid configuration, with excellent cycling stability and capacity retention after prolonged cycling. High surface area, short diffusion path and good conduction of the Cu2O films are considered to be responsible for the good electrochemical performance, along with the use of the polymeric electrolyte which is directly formed in situ on the electrode film surface. The present findings can provide a new and easy approach to fabricate nanocomposite films with interesting performance as negative electrode particularly for the next generation of flexible all-solid-state Li-ion microbatteries.

Fabrication and Characterization of NOR-Type Tri-Gate Flash Memory with Improved Inter-Poly Dielectric Layer by Rapid Thermal Oxidation

Floating-gate (FG)-type tri-gate flash memories with an improved inter-poly dielectric (IPD) layer have been successfully fabricated by introducing a newly developed rapid thermal oxidation (RTO) process, and their NOR-mode operation including threshold voltage (Vt) variations before and after one program/erase (P/E) cycle have been systematically investigated. It was experimentally confirmed that the gate breakdown voltage (BVg) is greatly increased from 12 to 19 V by introducing the RTO process thanks to the high quality and thin thermal silicon dioxide (SiO2) formation on the FG surface and etched edge regions, which effectively blocks the leakage pass of the IPD layer. A source–drain (SD) breakdown voltage (BVDS) as high as 4.5 V was obtained even when the gate length (Lg) was as small as 117 nm. It was also experimentally confirmed that the memory window increases with increasing gate voltage (Vg) in NOR-mode programming thanks to the increased efficiency of channel hot electron (CHE) injection. The developed tri-gate flash memory with improved IPD layer is useful for the further scaling of NOR-type flash memory.

Facile fabrication of cuprous oxide nanocomposite anode films for flexible Li-ion batteries via thermal oxidation

In the present work, nanostructured Cu2O films are directly grown from a Cu metal foil by means of a rapid thermal oxidation process. The structural characteristics of the films are investigated by field emission scanning electron microscopy, X-ray diffraction and attenuated total reflectance Fourier-transformed infrared spectroscopy. The electrochemical behaviour is investigated in both lithium (liquid electrolyte) and all-solid lithium polymer cells. At a discharge/charge rate of C/5, the films can provide a specific capacity greater than 220 mAh g−1 in the all-solid configuration, with excellent cycling stability and capacity retention after prolonged cycling. High surface area, short diffusion path and good conduction of the Cu2O films are considered to be responsible for the good electrochemical performance, along with the use of the polymeric electrolyte which is directly formed in situ on the electrode film surface. The present findings can provide a new and easy approach to fabricate nanocomposite films with interesting performance as negative electrode particularly for the next generation of flexible all-solid-state Li-ion microbatteries.

Formation, rapid thermal oxidation and passivation of solar grade silicon nanowires for advanced photovoltaic applications

Uniform and regular silicon nanowires (SiNWs) arrays are fabricated on both sides of solar grade silicons (SiGS) by silver assist-electrochemical etching. SiNWs arrays exhibit an excellent antireflection character with an overall reflectance of 2% in the range from 300 to 1000nm. More importantly, the effective lifetimes of the symmetric SiNWs/Si structures decreased due to the high densities of dangling bonds and surface defects. Surface passivation to overcome lifetime degradation is realized by means of rapid thermal oxidation (RTO). Following rapid oxidation, Fourier Transform Infrared spectroscopy reveals that oxygen diffusion is enhanced inside silicon nanowires where the morphological structure is preserved during RTO. Moreover, it is shown that even the rapid thermal oxidation process is not effective to recover initial τeff due to the high density of imperfections involved during nanowires formation and the contamination level induced by silver. The interdiffusion between residual silver and metal contaminants in the core of the nanowire can probably limit the passivation effect due to the segregation of metal atoms at SiO2 and to the redistribution of both impurities across the wire.

Evaluation of the WOx Film Properties for Resistive Random Access Memory Application

The formation condition, microstructure, and growth kinetics of the WOx layer for WOx resistive random access memory are investigated. To understand the optimal condition for the rapid thermal oxidation process which forms the WOx layer, various annealing temperature and annealing time are systemically studied through transmission electron microscopy, X-ray diffraction, Raman spectra analyses and electrical characterizations. The growth kinetics for WOx under rapid thermal oxidation is found similar to the one for thermal oxidation on silicon. The electrical forming voltages of the WOx cells are also found independent from the oxide thickness, which further suggests the switching behavior of WOx resistive random access memory takes place at the interface but not the bulk.

Ultrathin Oxide Passivation Layer by Rapid Thermal Oxidation for the Silicon Heterojunction Solar Cell Applications

It is difficult to deposit extremely thin a-Si:H layer in heterojunction with intrinsic thin layer (HIT) solar cell due to thermal damage and tough process control. This study aims to understand oxide passivation mechanism of silicon surface using rapid thermal oxidation (RTO) process by examining surface effective lifetime and surface recombination velocity. The presence of thin insulating a-Si:H layer is the key to get highVocby lowering the leakage current (I0) which improves the efficiency of HIT solar cell. The ultrathin thermal passivation silicon oxide (SiO2) layer was deposited by RTO system in the temperature range 500–950°C for 2 to 6 minutes. The thickness of the silicon oxide layer was affected by RTO annealing temperature and treatment time. The best value of surface recombination velocity was recorded for the sample treated at a temperature of 850°C for 6 minutes at O2flow rate of 3 Lpm. A surface recombination velocity below 25 cm/s was obtained for the silicon oxide layer of 4 nm thickness. This ultrathin SiO2layer was employed for the fabrication of HIT solar cell structure instead of a-Si:H, (i) layer and the passivation and tunneling effects of the silicon oxide layer were exploited. The photocurrent was decreased with the increase of illumination intensity and SiO2thickness.

Near-surface processing on AlGaN/GaN heterostructures: a nanoscale electrical and structural characterization

The effects of near-surface processing on the properties of AlGaN/GaN heterostructures were studied, combining conventional electrical characterization on high-electron mobility transistors (HEMTs), with advanced characterization techniques with nanometer scale resolution, i.e., transmission electron microscopy, atomic force microscopy (AFM) and conductive atomic force microscopy (C-AFM). In particular, a CHF3-based plasma process in the gate region resulted in a shift of the threshold voltage in HEMT devices towards less negative values. Two-dimensional current maps acquired by C-AFM on the sample surface allowed us to monitor the local electrical modifications induced by the plasma fluorine incorporated in the material.The results are compared with a recently introduced gate control processing: the local rapid thermal oxidation process of the AlGaN layer. By this process, a controlled thin oxide layer on surface of AlGaN can be reliably introduced while the resistance of the layer below increase locally.

Design and Fabrication of Nanostructures Silicon Photodiode

A highly sensitive (metal/nanostructure silicon /metal) photodiode has been fabricated from rapid thermal oxidation (RTO) and rapid thermal annealing (RTA) processes,Of nanostructures porous silicon prepared by laser assisted etching . Photoresponse was investigated in the wavelength rang of (400-850nm) . A responsivity of (3A/w) was measured at (450 nm) with low value of dark current of about ( 1 µA /cm2 ) at 5 volt reverse bias.

Formation and microstructural characterization of In 2O 3 sheath layer on InN nanostructures

An In 2O 3 sheath layer was formed on an InN nanostructure by a rapid thermal oxidation process. Rounding and bursting phenomena were observed as the progression of the oxidation process was followed. InN/In 2O 3 core-shell structures were identified as intermediate structures. After a 20 min oxidation, the InN nanostructures were completely transformed to an In 2O 3 phase. InN and In 2O 3 had wurtzite (WZ) and body-centered cubic (BCC) structures, respectively. The preferred orientation relationship of <1 1 2 ¯ 0> WZ//<1 1 0> BCC and {0 0 0 1} WZ//{ 1 ¯ 1 1} BCC was observed between InN and In 2O 3. Cracks in burst nanostructures were generated at the corners and penetrated along the <1 1 2 ¯ 0> directions.

Effects of Photons on 4H-SiC Rapid Thermal Oxidation Using Nitrous Oxide Gas

Rapid thermal processing (RTP) has been evaluated as an alternative to conventional furnace technique for oxynitridation of 4H-SiC. Nitrous oxide under atmospheric pressure conditions was used as oxidizing gas. The beneficial effect of high energy photons, coming from the RTP halogen lamps, leads to an enhancement of the molecule dissociation and an augmentation of the diffusion rate of dissociated species in the growing oxide. Compared to classical oxidation, the net effect is not only to increase the growth rate but also to result in dielectrics that exhibit a reduced trapped charge, a more stable oxide/4H-SiC overall structure, and a better (less defective) interface. Further optimization, combined with a better understanding of the rapid thermal oxidation process, should provide new issues for the growth of gate oxides in the SiC microelectronic industry.