We demonstrate a new purely optical based method for the excitation and detection of acoustic and thermal disturbances in thin films. This technique is applied to the determination of the viscoelastic properties of unsupported and silicon supported polyimide thin (∼1 micron) films. We show how this technique can be used to detect film delaminations and suggest how it may be used to probe film-substrate adhesion quality.

Implantation of 1.8×1018O+/cm2 into silicon results in a buried oxide (BOX) layer, nominally 400 nm thick. The as-implanted BOX has ∼1020 cm−3 dangling bonds, ∼1020cm−3 reactive sites for interaction with H (D); the dielectric properties are ill-defined, and, similarly to densified or ion-bombarded silica glass, the SiO2 network contains an increased proportion of high energy Si-O bonds, i.e. it is “strained”. After annealing above 1300°C the properties approach those of thermally grown SiO2, the dangling Si bonds are eliminated, the D-uptake decreases, the Si/SiO2 interfaces become sharper, and the dispersed silicon agglomerates into clusters of various kind. However, the properties of BOX are still significantly different from those of thermally grown SiO2 films as shown by pronounced electron trapping, large concentration of different hole traps, decreased etch rate in HF, increased D-uptake and E' center generation rate, as well as by increased bulk conduction and the presence of localized conducting defects. These phenomena are likely to be related to some oxygen deficiency, e.g. O3SiO3 groups, as oxygen treatments reduce, but not completely eliminate, the difference between BOX and thermal oxide.

Silicon-on-insulator (SOI) wafers made by standard energy (150–200 keV) Separation by IMplantation of Oxygen (SIMOX) processes have shown great promise for meeting the needs of radiation-hard microelectronics. However, if SIMOX material is to become a competitive substrate material for manufacturing commercial integrated circuits, the cost of the SIMOX wafers must be greatly reduced. The low energy SIMOX (LES) process accomplishes the needed reduction in cost by producing ultrathin layers which require much lower ion doses. These ultrathin layers are necessary for the next generation of commercial ultra high density CMOS integrated circuits, and must be of very high quality to be utilized for commercial applications. In this paper we discuss characterization of ultrathin LES structures.

Low temperature electron spin resonance (ESR) measurements were carried out on a broad range of separation by implantation of oxygen (SIMOX) substrates. The post-implantation forming anneal (T 1325°C) was observed to induce a donor in the SIMOX structure, more specifically, a shallow effective mass donor in Si of axial symmetry and preferential alignment along [001], likely an oxygen-related heat-treatment donor. Controlled etching back experiments revealed that the donor defects reside in an interfacial Si layer of at least 600$$A thick at both sides of the buried oxide layer reaching a local volume density of about 1018 cm−3. In the flat band situation, the donor was observed to be in a diamagnetic, ESR non-active state. Downward sweeping of the Si energy bands near the buried oxide interfaces, relative to the Fermi level, either by in situ positive ate biasing of large area metal-oxide-silicon capacitors fabricated on the buried oxide or γ7-irradiation induced positive charging of the buried oxide, was observed to alter the ionization state of part of the donors into an ESR-active state.

Spectroscopic ellipsometry has been used to characterize Poly-Si, prepared with the bulk LPCVD technology and SIMOX samples. SIMOX samples were prepared by implantation of the oxygen ion (≈ 1.8×1018ions/cm 2 at 200keV) of the c-Si substrate and annealing at 1300°C for 5 h. The measurements were taken at angles of incidence of 65 and 70 degrees in the wavelength range from 260 to 860 nm. The analysis of the data identified the presence of the inhomogeneity in the poly-Si layer and slight deviation of the Si layer optical constants spectra from that of the c-Si in the SIMOX sample. A method is presented that provides a step by step procedure for interpretation of the spectroscopic ellipsometry measurements.

Radiation hardening of SIMOX buried oxides by nitridation is demonstrated in this paper. Bare SIMOX oxide substrates, obtained by selective reactive ion etching of the top silicon film, were nitrided by annealing in ammonia at a high temperature. Al-Si thin film capacitors were fabricated on the SIMOX oxide and also on concurrently processed dry thermal oxides of similar thickness. Radiation hardness was tested by C-V measurements before and after the exposure to x-rays in an ARACOR x-ray source. SIMOX oxides were found to be inherently more resistant to radiation damage than the thermal oxides. Nitridation improved the radiation hardness of SIMOX oxides similarly to that of thermal oxides. Reoxidation nearly reversed the radiation hardening effect of nitridation in these thick (> 300 nm) oxides. For example, the following shifts in the flat band voltage were obtained when the capacitors were biased with ±5 V on the Al-Si dots and exposed to 100 krad (SiO2): -24 V for SIMOX oxide, -14.2 V for nitrided SIMOX oxide, and -22.8 V for reoxidized nitrided SIMOX oxide.

Properties of ultrathin (— lOnm) silicon nitride films on single crystal Si, InP and GaAs have been studied using Raman spectroscopy, medium energy ion scattering (MEIS), variable-energy positron annihilation spectroscopy and x-ray photoelectron spectroscopy (XPS). The silicon nitride films were prepared by remote microwave plasma chemical vapour deposition (RPCVD). The results showed that oxidation of the film due to air exposure was restricted to the near surface with an oxygen penetration depth no greater than 2 nm. The residual stress in the as-grown films was substrate-dependent. For films on Si (100), the film induced residual stress was compressive with a value of 0.5GPa. Annealing at 500°C for 60 minutes resulted in a complete release of the residual stress. Vacuum annealing at a temperature below 500° C also led to changes of the electrical properties in the films but not the substrate.

We find a significant alteration of the surface properties of SI- GaAs as a result of a thermal treatment with SiO under vacuum. Low temperature photoluminescence measurements reveal a tenfold increase in emissions attributed to free or donor bound excitons and the exciton bound to a silicon acceptor. A paramagnetic center is also generated as a result of this treatment. The EPR signal has a g-value of 2.0017 and a linewidth of 0.1 mT. The enhanced photoluminescence and the EPR signal are both quenched by a short exposure to hydrogen plasma at room temperature. Chemical and spectroscopic evidence indicates that the resonance is due to a silicon related center near the GaAs surface. The surface stabilization is attributed to a reaction or incorporation of SiO with the arsenic depleted GaAs surface.

We have developed a new electrochemical passivation method to obtain a quite stable sulfide layer on GaAs surface. This layer is very thick and contains a mixture of Ga, As, S, O and H compounds. The photoluminescence (PL) spectrum of such anodic sulfurized GaAs surface shows big intensity enhancement as compared with that of as-etched GaAs samples; No visual intensity decay occurs under laser beam illumination, which maintains for more than seven months. The structure and composition of the passivation layers are investigated by the X-ray photoelectron spectroscopy and the mechanism of the layer formation is suggested.

A combination of Electron Cyclotron Resonance (ECR) plasma, electrochemical, and chemical growth process were examined to synthesize dielectric surface passivation layers on InSb. The material properties of ECR-grown SiOx Ny on InSb at temperatures from 30°C to 250°C were investigated. Composition analysis was done using Rutherford backscattering spectrometry (RBS) and elastic recoil detection (ERD). The electrical quality of the passivation layer was characterized with capacitance-voltage (C-V) measurements on metal-insulator-semiconductor structures over the frequency range from 1 kHz to 1 MHz. Sulfided layers, Si3ON2 on InSb, and sulfided layers capped with S3ON2 all exhibited good C-V properties consistent with interface state densities on the order of 1011/cm2-eV, and flatband voltages of magnitude less than 1 V. The difference in adhesion of Si3N4 on InSb and the adhesion of Si3ON2 on InSb was described in terms of the strength of the bonding at the dielectric-InSb interface. This work is the first to demonstrate passivation of an InSb surface with high-quality ECR silicon oxynitrides grown at room temperature.

Ellipsometry and XPS investigations of RF plasma grown native oxide and C-V measurements of its interface were performed.

Strong dependence of the composition of the plasma grown native oxides and electric properties of MIS structures on the time of plasma treatment has been observed. The greater the content of stable polyphosphate phase of [InxPyOz] is in the native oxide composition, the better parameters of its interface with InP (NS 11 cm−2 eV−1 and the hysteresis of C-V characteristics≤0.2 V) and the lesser C-V drift after treatment may be achieved. Plasma oxidation results in creating a negative effective oxide charge density.

Investigations of plasma grown native oxides on indium phosphide carried out recently [1,2] have shown that these oxides exhibit properties which are promising to be used in MIS structures on InP, due to their stable composition which includes [InxPyOz]n polyphosphate phase mainly and due to reduced density of interface states (Nss<1011 eV−1 cm−2). It has been shown also that MIS structures with plasma native oxides exhibit C-V characteristics shifted towards positive values of voltage bias. The flat band shift is assigned to a negative charge injected into oxide film during plasma oxidation. The presence of this negative charge in plasma grown native oxides on InP may cause instability of electric properties of MIS structures [2].

The aim of this work was to make an attempt to influence upon negative effective oxide charge density by means of hydrogen plasma treatment.