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Earlier experimental findings concluded that electromigration voids in these meandering stripe test structures were not randomly distributed and that void nucleation frequently occurred sub-surface at the metal/thermal oxide interface. The data showed a strong correlation between void area, void growth rate and stripe segment length [1]. The influence of mechanical stress on electromigration damage in these test structures has been examined by applying tensile stresses to both passivated and unpassivated samples. The stress distributions are calculated using finite element analysis for each of the test conditions. The resulting impact on electrornigration voiding, as well as mechanical stress voiding, and lateral hillock formation is discussed.

Electron states at the SiO2/4H-SiC interface have been investigated using capacitor structures and especially, the influence of excess nitrogen, introduced by ion implantation, at the interface is studied in detail. Implanted and nonimplanted n-type samples with an interfacial concentration of nitrogen of similar to 10(19) cm(-3) and 10(16) cm(-3), respectively, were analyzed by capacitance-voltage (C-V) measurements, performed at different temperatures and probe frequencies, and thermal dielectric relaxation current (TDRC) measurements performed in the temperature range of 35-295 K. Three main categories of electron states are disclosed, true interface states (D-it), fast near interface states (NIToxfast) and slow near interface states (NIToxslow). The density versus energy distributions of D-it and NIToxfast have been deduced from the TDRC data and they are shown to give a close quantitative agreement with the shape and frequency dependence of the C-V curves. Further, the amount of NIToxslow extracted from TDRC is demonstrated to be responsible for the parallel shifts and hysterezis effects occurring in the C-V characteristics. All three categories of electron states are reduced in concentration in the implanted samples. This holds particularly for NIToxfast with a peak at similar to 0.1 eV below the conduction band edge of 4H-SiC that is suppressed by at least two orders of magnitude relative to the nonimplanted samples. The decrease for D-it is also substantial (a factor of similar to 10) while the loss for NIToxslow is considerably smaller (only similar to 30%). The results provide firm evidence that NIToxfast and NIToxslow do not originate from the same kind of defect center.

We investigated the thermal stability and the electron irradiation damage of the ordered structure in the thermal oxide layer on Si substrates. The diffraction peak from the ordered SiO 2 shifted to the lower angle side, and the intensity decreased after thermal annealing above 950°C, indicating the decrease in density and the disordering of the structure. The least-squares fitting analysis assuming the quasi-amorphous structure showed that the ordered SiO 2 was relatively stable at the SiO 2 /Si interface and the root-mean-square displacement of the atoms at the interface was 0.22 nm. The ordered structure was also degraded by electron irradiation at a dose of less than 6.6 C/cm 2 .

The results of charge trapping and thermal annealing in X-ray irradiated SiO2 are presented. A comparative study is made between thermal oxide and SIMOX buried oxide behavior. At low dose (10 krad(SiO2)), X-ray induced charge trapping is found to be very different in thermal and SIMOX oxides. Results are interpreted in terms of a relatively large bulk trapping in SIMOX whereas thermal oxide behavior is dominatedby interface trapping. However, at high dose, both oxides behave similarly and are dominated by interface trapping. Etch-back experiments performed on SIMOX irradiated at 10krad (SiO2) and 1 Mrad (SiO2) reveal these two trapping regimes. Isochronal annealings have been performed up to 300°C on irradiated samples. Recovery data are interpreted assuming an energy distribution of trapped charge densities. Detrapping energies located at about 1.05 eV and 1.35 eV have been obtained in SIMOX whereas the thermal oxide exhibits a unique peak at 1.35 eV. Based on these data, SIMOX and thermal oxides are demonstrated to differ significantly.

Oxygen-vacancy defects (E') generated at the surface of buried SiO2 layers formed by O+ implantation during the separation by implantation of oxygen (SIMOX) process have been studied by electron spin resonance (ESR) at 4.2 K. The E' damage was generated during exposure to a dc Ar glow discharge that produces defects predominantly in a surface layer of ≈100 Å thick, reaching local volume densities at the surface up to 8 × 1019 cm−3. This glow discharge exposure, alternated with step-by-step etch back, allowed mapping of a defect generation sensitivity depth profile of the buried oxide (BOX) layer, revealing a fairly uniform sensitivity with a strong decline towards the BOX/substrate interface. Besides the usual E' γ signal, the E'δj center — a delocalized variant of the E' center — has been newly observed in the BOX. Reoxidation of the BOX was observed to reduce the E' sensitivity close to that of regular dry thermal oxide (≥ 29 times lower), while the E'γ signal could no longer be generated, again similar to conventional thermal oxide. These data suggest a revision of the model for the E' defect. In general, the results strongly suggest that the buried oxide contains excess Si, exceedingly so near the BOX/substrate interface.

The reliability of thermal oxides grown on an n-type 4H-SiC(0001) was investigated using an area-scaling method, and the influence of dislocation defects on the time-dependent dielectric breakdown characteristics of thermal oxides was examined. A thermal oxide was grown by dry oxidation at 1200 °C followed by nitrogen post-oxidation annealing. Using the area-scaling method, the time-to-breakdown (tBD) distribution curves of metal–oxide–semiconductor (MOS) capacitors with different gate area sizes were converged to a single one. It was clearly shown that origins of dielectric breakdown are edge breakdown and dislocation-related breakdown for steep and gradual slopes of the area-scaling normalized tBD distribution curve, respectively. In addition, a yield analysis of MOS capacitors quantitatively indicated that both threading screw dislocation and basal plane dislocation are predominant killer defects for the dielectric breakdown of thermal oxides on the 4H-SiC(0001) face.

The nucleation and growth of SiO 2 , as a function of surface condition, was investigated using in situ medium-energy ion-scattering analysis. The amount of SiO 2 required for saturation on the thermal oxide and on the chemical oxide was found to be 0.75 and 3.84 X 10 14 Si/cm 2 , respectively. The growth of SiO 2 on the initial HfO 2 surface increased as a function of HfO 2 coverage and growth when the HfO 2 coverage over 1 monolayer (ML) becomes saturated when the coverage of SiO 2 is ∼7 X 10 14 Si/cm 2 , which corresponds to a coverage of 1 ML SiO 2 . The nucleation of SiO 2 greatly depends on the initial surface conditions. In addition, the nucleation of SiO 2 has a tendency to become saturated, regardless of the initial surface conditions.

We have fabricated ultrathin SiO sub 2 layers between 5 and 10 nm. Conventional thermal and rapid thermal oxide forming processes were applied as well as a low temperature chemical vapor deposition (CVD) process. With these dielectrics, single layers have been produced for structural investigations by infrared (IR) absorbance spectroscopy. The IR-spectra of the thermal oxides and the postannealed CVD-oxide revealed nearly the same vibrational properties. MOS devices such as capacitors and field effect transistors (FETs) have been fabricated with these dielectrics. Breakdown measurements revealed a reduced high field breakdown with a broadened distribution for CVD layers as compared to the results obtained for thermal oxides. This effect was reduced with decreasing thickness. From transfer characteristics and charge pumping measurements on FETs, no considerable difference in the number of fixed oxide charge and interface trapped charge density was observed for all oxides. The device pro perties appear to be more strongly effected by substrate dopant concentrations and the oxide thickness than by the intrinsic properties of the oxide.

In this paper, we will present a study of the thermal reaction of AsjOs with GaAs at temperatures below 550°C using monochromatic X-ray photoelectron spectroscopy (MXPS). A solid-state interface reaction of 4GaAs + 3AS2O5 → 2Ga2O3 + 3AS2O3 + 4As, which includes the usual native oxide thermal reaction: 2GaAs + AS2O3 → Ga2O3 + 4As, as well as a decomposition reaction AS2O5 → AS2O3 + O2 is responsible for the thermal reaction in this temperature range.

The chemistry of SiO2 deposition from N20-SiH4 plasma was studied by line-ofsight mass spectrometry coupled with film analysis. If rf power and N2O flow are sufficient, more than enough O atoms are available to convert all of the SiH4 to SiO2, and good electrical characteristics (IV and breakdown) are then obtained with or without He dilution. Gas-phase SimHn(OH)p species make a minor contribution to the deposition and may be the source of the OH in the film. Both [OH] and electron trapping are much larger than for thermal oxide, with or without He dilution.

The preparation of InSb (001) oxygen-free surfaces by thermal annealing at relatively low temperatures under molecular hydrogen flow is reported. This process is compared with thermal oxide desorption (TOD) at 400°C under ultrahigh vacuum conditions. Molecular hydrogen cleaning (MHC) at substrate temperature of 250°C and at hydrogen pressure of 5×10−6Torr resulted in complete desorption of the native oxide layer. Furthermore, no carbon contamination was observed on the surface following this treatment. The surface morphology of the samples following this process was found to be very smooth without any droplet structure. The In:Sb surface stoichiometry was nearly 1:1 along the MHC process. In addition, annealing the sample at 400°C in vacuum after oxide removal by MHC maintains the smoothness and the stoichiometry of the surface. In contrast, TOD at 400°C of an oxidized InSb surface in vacuum does not result in complete oxide removal from the surface. Furthermore, small droplets associated with In are prod...

Surface pit formation is observed to occur for conventional thermal oxide desorption, regardless of the GaAs surface index. The resulting surface roughening can be substantially reduced by depositing an appropriate amount of Ga in the absence of As flux. The amount of Ga required to optimize the quality of the oxide-free GaAs surface is found to be different for different indexed substrates and is dependent on the oxide thicknesses. Due to the flexibility of the GaAs surface reconstruction, the Ga-triggered oxide desorption is observed to be much more robust than was previously believed.

Inversion mode n-channel MOSFETs have been built on (6H) silicon carbide (SiC) substrates, with thermal oxide as the gate insulator, and with channel lengths ranging from 1 to 25 mu m. Drain leakage currents lower than 0.04 pA/ mu m channel width have been experimentally obtained at temperatures up to 400 degrees C and V/sub d/=5 V.

We have characterized the Si/Si 0.6 Ge 0.4 heterostructure formed by two-step solid-phase reaction. Single crystalline behavior is evidenced by X-ray diffraction. In sharp contrast to conventional strain-relaxed SiGe, an extremely smooth surface close to the Si substrate is measured by cross-sectional transmission electron microscopy and atomic force microscopy. Good material quality is further evidenced from the near identical current-voltage characteristics for thermal oxide grown on Si/Si 0.6 Ge 0.4 and on the Si control sample.

Strain and stress at the Si surface have been studied by photoreflectance (PR) spectroscopy. A Si diaphragm structure has been fabricated in order to produce the surface strain caused by N2 gas pressure which changes the PR spectra of the Si diaphragm. The transition energy obtained from the PR peak energy of approximately 3.4 eV is proportional to the surface stress, which is calculated by elastic analysis. Additionally, PR spectroscopy was applied to measure stress at the interface between the Si and thermal oxide. As the SiO2 growth temperature increases, the interface stress decreases. From our experimental results, it is considered that PR spectroscopy is effective as a contactless and nondestructive monitoring technique for Si surface stress.

Polycrystalline silicon, when highly doped, is commonly used in microelectronics applications such as gates and interconnects. The packing density of integrated circuits can be enhanced by fabricating multilevel polycrystalline silicon films separated by insulating SiO2 layers. It has been found that device performance and electrical properties are strongly affected by the interface morphology between polycrystalline silicon and SiO2. As a thermal oxide layer is grown, the poly silicon is consumed, and there is a volume expansion of the oxide relative to the atomic silicon. Roughness at the poly silicon/thermal oxide interface can be severely deleterious due to stresses induced by the volume change during oxidation. Further, grain orientations and grain boundaries may alter oxidation kinetics, which will also affect roughness, and thus stress.Three groups of polycrystalline silicon films were deposited by LPCVD after growing thermal oxide on p-type wafers. The films were doped with phosphorus or arsenic by three different methods.

Copper decoration was performed on silicon wafer back sides covered with a low thermal oxide (LTO) layer. Under the conditions applied, 50 V across the electrolytical cell for about 5 min, patches with a lateral extension of 150 μm and larger were generated, and can be observed visually with haze light illumination. The defects on the wafer back side causing decoration have characteristic lateral dimensions on the order of few micrometers, heights and depths of well below I μm up to several micrometers, and originate mostly from interactions of the silicon wafer back side with particles. In the case of silicon wafer back sides manufactured with intentional damage for external gettering and covered with a LTO, only such defects are clearly marked by copper decoration that deviate from the characteristic back side texture. Thus, copper decoration is a method that, for the first time, allows the systematic investigation of defects with micrometer dimensions on present standard commercially available and coated silicon wafer back sides. Location of the defects is accurate enough for high resolution characterization equipment such as atomic force microscopy or those that can be used for chemical analysis.

Using 17 O-enriched thermal oxide on silicon, we have measured the hyperfine interaction between dangling bonds at the (111) interface (P b centers) and oxygen. Our analysis shows that the P b center interacts with a single oxygen atom in the SiO 2 .

Selective oxidation on GaAs operated at near room temperature, by a liquid phase chemically enhanced method using photoresist as a mask, is proposed and demonstrated. Because of the low temperature and electroless features of the oxidation method, the process is simple, economic and reliable. Good electrical insulating properties comparable with those of thermal oxide have been obtained. According to the results of X-ray photoelectron spectroscopy, the chemistry of the oxide surface is stable after thermal annealing. The thermal stability shows the potential for device fabrication.

It was found, from combined measurements of the surface microroughness of silicon oxide film and the SiO2/Si interface structure, that the surface microroughness of thermal oxide film formed on a Si(111) surface changes periodically with the progress of oxidation in accordance with periodic changes in interface structures. Therefore, the changes in interface structures can be detected by measuring the oxidation-induced surface microroughness.

Shimura, T., Misaki, H. & Umeno, M. (1996). Acta Cryst. A52, C465, https://doi.org/10.1107/S0108767396080932.

To increase the rate of oxidation of Si in N2O, oxygen was added to N2O. The effect of varying the percentage of N2O in the total gas on the quality of the oxide was examined. It was experimentally determined that for a percentage of N2O more than about 50, the quality of the oxide is comparable to the oxide grown using pure N2O. This may suggest that to improve the quality of thermal oxide on Si (especially its hardness against hot carriers) a certain level of nitrogen atoms is sufficient. Increasing the nitrogen content of the oxide beyond that level does not further improve the oxide hardness and only results in smaller oxide growth rate.

We have investigated optical properties and microstructures of Si+-implanted thermal oxide films grown on crystalline Si wafer, as-implanted and after subsequent annealing. We found two types of visible luminescence bands similar to those of silica glasses: one peaked around 2.0 eV, observed in as-implanted specimens and annealed completely at about 600 °C, and the other peaked around 1.7 eV, observed only after heating specimens to about 1100 °C, the temperature at which Si segregates from SiO x . Though the shapes of these luminescence spectra are quite different from those having been observed in Si+-implanted silica glasses caused by interferences, the origins of these bands are the same as in silica glasses. Moreover, the direct evidence for the formation of nanometer-sized Si crystals in amorphous silicon dioxide matrix after annealing at 1100 °C is presented by high-resolution transmission electron microscopy.

The dose repeatability and uniformity of certain low dose implants are of critical importance in optimizing yields in VLSI processes. The need to closely control implant variations motivates the use of instruments to monitor implanted wafers. However, all low dose implant measurement techniques can produce apparent dose repeatability and uniformity variations not related to the ion implanter which will dominate the measurement unless appropriate controls are employed. This investigation identifies several sources of apparent dose variation which must be controlled to obtain precision when using modulated reflectance damage measurements of implanted wafers. The effects of measurement procedure, thermal oxide density, thickness and uniformity on indicated dose when using a boron, × 1012/cm2, 100 keV implant are described. Controls which will allow precise low dose implant characterization are identified.

The XPS method combined with argon-ion etching has been applied in order to study the chemical depth profile of surface thermal-oxide layers on GaP(). The influence of the ion etching process on the depth profile has been studied. The deviation of the measured profile from the true one was caused mainly by the fact that atoms are not removed layer by layer by ion etching. The thermal oxide formed on GaP has been identified as GaPO4. It has been found that the width of the transition region increases as the thickness of the surface oxide layers increases. For example, when GaP() is oxidized at 700°C for 15 min, a surface oxide layer of 340 A is formed, and the transition region has a width of 175±73 A.

The morphology and distribution of phases resulting from the thermal oxidation of GaAs at 500 ° C has been investigated by application of high-resolution transmission electron microscopy to cross-sectioned specimens. The oxide layer grown at 500 ° C was found to consist of epitaxial Y-Ga2O3 with hexagonal As precipitates at the interface with GaAs. The evolution of the oxide/GaAs interface morphology is discussed in light of these results.

We have investigated plasma enhanced chemical vapor deposited (PECVD) and thermal oxides using electron spin resonance (ESR). We have been able to show that electron injection into PECVD oxides results in the generation of neutral E′ centers. The E′ center is an unpaired electron on a silicon backbonded to three oxygens. However, in thermal oxides, E′ centers are generated by hole injection, not electron injection; thermal oxide E′ centers are positively charged. Thus, there are fundamental differences in the point-defects in thermally grown and PECVD oxides.

MNOS capacitors (metal-nitrite-oxide-semiconductor) have been used to study the effects of memory oxide growth and post-oxidation annealing conditions on retention and endurance of MNOS devices. Results of this study indicate that write/erase cycling causes a decrease in memory window size after 10 5 cycles, a shift of the memory window center toward more positive values of threshold voltage, and an increase in surface state density for cycling above 10 6 cycles. The retention data presented indicates that the memory window decay rate for ±25 V writing pulses is only a function of the initial window size. The collapse of the memory window to zero volts is predicted to occur after 10 16 sec for native oxide devices and after 10 18 sec for thermal oxide devices. HCl annealing of the memory oxide does not have a significant effect on either endurance or retention.

La presence d'une couche mince d'oxyde thermique a la surface de l'aluminium provoque la croissance d'oxyde cristallin supplementaire (γ'-Al 2 O 3 ) au cours de l'anodisation subsequente dans une solution aqueuse de phosphate

XPS and spectroscopic ellipsometry combined to chemical etching depth profiling techniques have been used to study the chemical composition of thin oxide films thermally grown on InP(100) in the 250–550°C range. It is shown that oxides are made up of a microscopic mixture of In 2 O 3 and InPO 4 with elemental P at the interface.

The infrared absorption spectra both of ultrathin plasma SiO 2 and of thermal oxide (15–100 nm) treated in RF O 2 plasma are investigated in the wave number range from 400 to 4000 cm −1 . A conclusion is made that the plasma oxide consists of amorphous and different kinds of crystalline phases. The IR spectra of plasma oxide depend slightly on the discharge parameters. The structure of the as-grown thermal oxide, thinner than 40 nm, is shown to have defects and the presence of crystalline phases is observed too. The IR spectra of these oxides are changed significantly after plasma exposure. The influence of RF O 2 plasma on the thermal oxide, thicker than 40 nm, is negligible with respect to structural changes.

Silicon dioxide layers deposited from the vapour phase at low temperatures are extensively applied in integrated circuit technology. Applications include doped oxide diffusion sources, protective layers and cross-over insulators in multilevel metallization systems. In this paper we show the feasibility of obtaining a SiO 2 Si interface whose electrical characteristics closely approach those of thermally grown SiO 2 Si sandwich structures. Interface state densities lying in the low 10 10 cm −2 eV −1 range have been determined from quasi-static C(V) measurements. The results of excess noise measurements made on deposited gate oxide and thermally grown gate oxide MOSFETs are in reasonable agreement with the interface state density measurements. C(V) dispersion and C(V) hysteresis measurements prior to and after exposure to 10 7 rad of 60 Co γ radiation are also presented. Potential applications of low temperature vapour-deposited oxides include the silicon on insulating substrate (SOS) technology where it is generally desirable to minimize high temperature processing steps. Other applications are in the field of impurity profile determinations using the MOS capacitor method. In these applications one desires to measure the original profile without having to deal with the additional complication of the diffusion and redistribution phenomena that occur unavoidably during high temperature thermal oxide growth.

Contact potential measurements by the Kelvin method were performed in vacuum on silicon wafers whose thermal oxide film was etched into the shape of a wedge. A given position along the oxide corresponded directly to a given depth and by scanning a reference electrode stripe across the wafer, information about the distribution of the oxide charge through the thickness was obtained. It was found that the oxide charge was positive and concentrated within a few hundred angstroms of the SiSiO2 interface.

Experimental data are presented for the influence of helium plasma on the electrical properties of Si−SiO 2 structures with dry thermal oxide (d=16−72 nm). It is found that for strongly damaged structures low temperature helium plasma introduces acceptor-type interface states near the conduction band edge and has an annealing effect on the deep acceptor-type states. It has also shown that the initial characteristics of the Si−SiO 2 structures and the gas used are critical for the plasma-forming of both the interface and inversion channel properties.

The growth kinetics and the electrical properties of silica layers obtained under infrared illumination have been studied. The growth rate is identical to that of thermal oxide layers in the range 950°C-1050°C. Furthermore their electrical properties compare favorably with those of thermal oxide layers La vitesse de croissance est identique a celle d'une couche obtenue par oxydation thermique entre 950 et 1050°C et leurs proprietes electriques se comparent favorablement a celles de leurs homologues thermiques

A high quality silica glass was used to passivate high-voltage power transistors. With the self-gettering ability, the interface state density of silica glass is reduced after heat treatment. The properties of this glass are analysed and compared with that of thermal oxide. Experimental results show its good properties for passivation. The characteristics of passivated high-voltage transistors are also discussed.

This paper compares the Auger and ESCA techniques used to characterize the interfaces of thermally grown and anodic oxides of InP and GaAs. In the anodic oxide of GaAs, the Ga–O bonding extends deeper into the GaAs than the As–O bonding. In the anodic oxide of InP, both the P–O and In–O bonding penetrate to the same depth. The anodic oxide–GaAs interface changes with electrolyte. There is elemental P at the interface of the thermal oxide on InP, but it was not possible to prove or disprove the existence of elemental As at the anodic oxide/GaAs interface. It was found that the ESCA technique provided much needed bonding information which greatly facilitates characterizing the interface. It appears essential that both composition and bonding be determined.

The influence of the thickness and structure of thermally produced aluminum oxides on the microscopic frictional response of aluminum auto body sheet alloys 6010-T4, 6009-T4, and 2036-T4 has been investigated. A variety of oxide thicknesses and structures were produced through variation of exposure temperature and quench medium. Coefficients of friction for the surfaces were subsequently determined using a tool steel slider under three conditions of lubrication: unlubricated sliding, lubrication with oil-based DG4247, and lubrication with water-based DA4251. For unlubricated sliding, friction was high for all alloys at low oxide thicknesses, corresponding to metal-to-metal contact and adhesive wear. With increasing thickness, friction coefficient changed in a manner controlled by the underlying strength of the material and the level of surface MgO. Lubricated sliding tests with DG4247 and DA4251 showed a uniformly low friction coefficient, independent of oxide thickness. However, after selective removal o...

The current understanding of the growth of thermal oxide films in terms of the transport properties of the oxides is reviewed. Emphasis is placed on examining quantitative relationships between the film growth rate and other measurable parameters of the oxides. The theories of film growth which are expected to apply in the extreme limits of thick films (Wagner) and thin films (Cabrera and Mott) are outlined. Particular attention is given to examining the expected limits of validity of these theories and to the various ways in which their predictions can be tested experimentally. The growth of a selection of important oxides is then discussed in the light of these two theories. The examples (CoO, NiO, ${\mathrm{Fe}}_{3}$${\mathrm{O}}_{4}$, ${\mathrm{Cr}}_{2}$${\mathrm{O}}_{3}$, ${\mathrm{Al}}_{2}$${\mathrm{O}}_{3}$, and Si${\mathrm{O}}_{2}$) have been selected such that together they serve to test the theories, have technological relevance, and exhibit a wide variation in behavior. The dominant role of diffusion along oxide grain boundaries in controlling the growth of the crystalline oxides is highlighted.

The growth rates of thermal oxides on InSb in dry and wet oxygen were determined and their physical and electrical properties studied. It was found that the oxides were electrically conductive. The diffusion masking capability of the thermal oxides was examined. The oxides were found permeable to Te and Se, but masked against the diffusion of Zn under practical diffusion regimes. Les vitesses de croissance des oxydes thermiques sur l'InSb dans l'oxygene see et humide et leurs proprietes physiques et electriques ont ete etudiees. Les oxydes ont ete trouves electriquement conductifs. La capabilite des oxydes thermiques de masquer la diffusion des impuretes etait examine: les oxydes ont ete trouves permeables pour Te et Se, mais masquaient la diffusion de Zn dans des regimes pratiques.

SIMS give specific informations on the diffusion of a tracer in growing oxide films and the depth distribution of impurities in low concentrations in the films. The valency of these dopants can be determined by XPS, thus permitting to explain their influence on diffusion processes.