Ion-implanted Silicon Layers Research Articles

Peculiarities of the electron structure of nanosized ion-implanted layers in silicon

The effect of implantation of Ba, P, B, and alkali element ions with a low energy (E 0 < 5 keV) on the electron structure of a thin surface region of p- and n-type Si(111) single crystals is investigated by photoelectron and secondary electron-electron spectroscopy. It is shown that irrespective of the ion species, high-dose ion implantation leads to a sharp narrowing of the band gap in silicon, which can be explained by overlapping of the wavefunctions of electrons of impurity atoms and the formation of the impurity subband overlapping with the allowed band. After implantation thermal annealing, SiP, BaSi, and SiB3 films of nano-sized thickness are obtained for the first time. Optimal regimes of ion implantation and subsequent annealing for the formation of silicide films are determined, and their electron structure is investigated.

Measurements of the optical absorption coefficient of Ar8+ ion implanted silicon layers using the photothermal radiometry and the modulated free carrier absorption methods

This paper presents a method of the measurement of the optical absorption coefficient of the Ar8+ ions implanted layers in the p-type silicon substrate. The absorption coefficient is calculated using a value of the attenuation of amplitudes of a photothermal radiometry (PTR) and/or a modulation free carrier absorption (MFCA) signals and the implanted layer thickness calculated by means of the TRIM program. The proposed method can be used to indicate the amorphization of the ions implanted layers.

Investigation of structure and phase transformations in silicon implanted with 12C + at room temperature

The methods of Auger-electron spectroscopy and of X-ray diffraction are applied to an investigation of C + ion implanted silicon layers. The ion energies are 40, 25, 17, 10, 6 and 3 keV for creation of a linearly decreasing profile of carbon in silicon or only 40 keV to obtain a concentration distribution which is approximately Gaussian. The microstructure and the phase composition of the implanted layers are studied experimentally to determine the dependence upon annealing temperature. The mechanism for creation of complicated multilayer structures during annealing is shown graphically. Formation of SiC crystallites begins at the sample middle layer and spreads to the surface layer and substrate as the annealing temperature increases. Crystallization of silicon amorphized by implantation begins both near the substrate and the sample surface and propagates to the middle of the layer with the Gaussian carbon distribution while in the layer with the linear distribution the crystallization comes about from the sample interior to its surface. After annealing at 1250°C, nearly 35% of the total volume of polycrystalline Si passes to c-Si from the substrate side for the samples with the Gaussian distribution and 45–50% for the samples with the linear distribution of carbon, respectively.

Regrowth-process study of amorphous BF 2 + ion-implanted silicon layers through spectroscopic ellipsometry

The recrystallization kinetics of BF 2 + ion-implanted silicon has been studied by means of spectroscopic ellipsometry. It has been found that the dielectric constant of the implanted layers depends on the energy, dose and ion-beam current. The activation energy of the regrowth process increases with ion peak concentration becoming saturated for the largest implanted doses. In the largest-dose samples implanted at low current a significant decrease of the regrowth rate was detected when the recrystallization front crosses the peak of the impurity distribution.

Characterization Of sic Layer Formed by C Ion Implantation ( ESR And IR Studies)

ABSTRACTCharacterization of C ion implanted silicon layers were performed by fourier transformation infrared ( FT-IR ) spectroscopy and electron spin resonance ( ESR ) methods. Microcrystalline β-SiC including amorphous Si are formed in the Si surface region by annealing at 1200 °C following hot ( 450 °C ) implantation. The ESR analysis revealed the presence of two kinds of defect centers in SiC layer formed by implantation, i.e. Si dangling bond ( g=2.0060, ΔHpp=6 Oe) in the amorphous Si and Si dangling bond with C atom neighbors ( g=2.0032, ΔHpp=3 Oe). Heating substrate during implantation prevents the formation of carbon clusters on the Si surface.

Application of Laser-Induced GHz Surface Acoustic Waves to Evaluate Ion-Implanted Semiconductors

The transient reflecting grating method has been used to characterize ion-implanted silicon layers and demonstrate its usefulness for nondestructive and remote evaluation of modified solid surfaces. The surface acoustic velocity, relaxation constant and signal intensity were measured as functions of ion dose. The results suggested that damage induced by implantation significantly affected the surface properties even under light dose conditions. The subnanosecond temporal resolution of the present method provided successful characterization of the implanted layers.

Amorphization of ion-implanted layers in silicon using photoacoustic detection

The influence of ion implantation in the thermal properties of silicon wafers at room temperature is investigated using the photoacoustic technique. It is suggested that the observed decrease of the values of both thermal diffusivity and conductivity, as the implantation dose increases, is due to the amorphization of the implanted layer.

STUDY ON DAMAGES IN ION-IMPLANTED Si USING TRANSIENT REFLECTING GRATINGS

The transient reflecting grating method has been used to characterize ion-implanted silicon layers. The signal intensity and relaxation constant were measured as functions of ion dose. The results suggested that damage induced by ion-implantation suppresses thermal diffusion even under a light dose condition.

Simulation of the Influence of Mechanical Stresses on the Kinetics of Crystallization of Ion-Implanted Silicon Layers under Pulse Heating

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Potentialities of new X-ray diffraction methods in structural studies of ion-implanted silicon layers

The potentialities of new X-ray diffraction methods – diffraction under total external reflection conditions and inclined Bragg diffraction – are considered in the application to silicon crystals implanted with 9 × 1013 80 keV P+/cm2, 2 × 1014 80 keV P+/cm2, 2 × 1015 30 keV P+/cm2 and 3 × 1015 30 keV P+/cm2. The methods are shown to be very sensitive to disturbances of the crystal structure in surface layers of 0.001 to 0.1 μm thickness. The amorphization of the implanted layers is measured with integral curves of X-ray diffraction under conditions of total external reflections and it is demonstrated that this method is very suitable for the detection of the amorphization doses of implantation. The strains of lattice spacing in two dimensions are studied in the layers with conventional and inclined Bragg reflection profiles. It is established that the strains are one-dimensional in a direction normal to the surface within an accuracy of Δd/d ∼ 10−4. Die Moglichkeiten von neuen Rontgenbeugungsmethoden – Beugung unter vollstandigen externen Reflexionsbedingungen und geneigte Bragg-Beugung – werden durch Anwendung auf Siliziumkristalle untersucht, die mit 9 × 1013 80 keV P+/cm2, 2 × 1014 80 keV P+/cm2, 2 × 1015 30 keV P+/cm2 und 3 × 1015 30 keV P+/cm2 implantiert werden. Es wird gezeigt, das die Methoden sehr empfindlich gegen Storungen der Kristallstruktur in Oberflachenschichten von 0,001 bis 0,1 μm Dicke sind. Die Amorphisierung der implantierten Schichten wird mit integralen Kurven der Rontgenbeugung unter Bedingungen der vollstandigen externen Reflexion gemessen und es wird gezeigt, das diese Methode fur die Bestimmung der Amorphisierungsdosis nach Implantation sehr geeignet ist. Die Spannungen des Gitters in zwei Dimensionen werden in Schichten mit konventionellen und geneigten Braggschen Reflexionsprofilen untersucht. Es wird festgestellt, das die Spannungen in Richtung der Oberflachennormale innerhalb einer Genauigkeit von Δd/d ∼ 10−4 eindimensional sind.

Structure modifications in AS+−ION implanted silicon layers during pulse thermal treatment

Abstract The silicon layers structure after As+−ion implantation and subsequent pulse annealings, which were carried out in nanosecond (Q-switched ruby laser) or/and few seconds (halogen lamps) time intervals, has been studied by transmission electron microscopy techniques. It has been shawn that the structure state is determined to a large extend by pulse annealing parameters. In the case of second pulse annealing the level of ion-implanted layer disordering affects considerably the obtained structure.

Epitaxial regrowth and defect formation during pulsed nanosecond annealing of amorphous layers. Part 1: Experimental results

Abstract The results of structure investigations of antimony ion-implanted silicon layers after the pulsed nanosecond annealing by ruby laser have been presented. Formation of micro-twins and tetrahedrons of stacking faults has been found to take place on the initial amorphous/crystalline Si interface for various degrees of liquid Si overcooling.

Control of explosive liquid-phase crystallization of ion-implanted silicon layers by double pulse laser irradiation

Control of explosive liquid-phase crystallization of ion-implanted silicon layers by double pulse laser irradiation

Studies of Defects and Limits of Solid Solubility in SPE Grown in and Sb Implanted Silicon

ABSTRACTTransmission electron microscopy (plan-view as well as cross-section) and high-resolution Rutherford backscattering and channeling techniques have been combined to investigate residual defects and substitutional concentrations of In and Sb in &lt;100&gt; and &lt;111&gt; orientations of ion implanted silicon layers after solid-phase-epitaxial (SPE) growth at 475–600°C. The maximum concentrations of Sb and In in substitutional sites were found to be, respectively, 1.3 × 1021 and 5.0 × 1019 cm−3 , exceeding the respective retrograde maxima by factors of 18 and 60. These results provide direct evidence of solute trapping and metastable alloying under solid-phase growth conditions. Accumulation of solute at the crystalline-amorphous interface was observed only for indium above a certain interfacial concentration. At still higher interfacial concentrations, the planar interface was observed to become unstable and SPE growth was retarded.

Production of radiation defects in silicon at different temperatures

Abstract Results of backscattering measurements of radiation damage in ion implanted silicon layers are presented and compared with the results of optical and electrical investigations. The influence of several implantation parameters on amount and depth distribution of radiation damage produced at low temperatures can be described by the energy deposited into nuclear processes. In this case the depth profile of refractive index change correlates with the damage distribution. With increasing temperature energy deposited into ionization processes becomes more and more important and the kind of defect nucleation changes. Both depth distributions of radiation damage and properties of the produced defects are different from those found after implantation at low temperatures. There are strong correlations between modified defect production characteristics at a given temperature and the mass of implantedions.

Crystallization of ion implanted silicon layers by the nanosecond laser pulses

Crystallization of ion implanted silicon layers by the nanosecond laser pulses

Kinetics of recrystallization in ion-implanted silicon layers

The kinetics of recrystallization of a silicon layer rendered amorphous by the implantation of 1015 phosphorous ions cm−2 of energy 80 keV is studied during isothermal warm-up with the help of Raman spectroscopy. The results indicate that this recrystallization occurs through a controlled growth at the interface between the amorphous and crystalline phases. The sharp change of the electrical conductivity which takes place at the crystallization temperature is correlated with the fraction which is crystallized.

Defect annealing investigation in ion implanted Si by CESR technique

Abstract The variations of both the linewidth δH[G] of the conduction electron spin resonance (CESR) and the conduction electron density N[cm−2] in the ion implanted silicon layers during annealing at 300° to 1000°C are presented. Defects responsible for CESR line broadening near the surface or near the average projected range of phosphorus ions are shown to have a similar nature. The results obtained provide direct evidence that the defects are clusters involving a few interstitial phosphorus atoms.

Experimental method for measuring both atom and carrier concentration profiles in the same sample of ion-implanted silicon layers by radioactive-ion implantation

An experimental method by radioactive-ion implantation for measuring both atom and carrier concentration profiles in the same sample of ion-implanted silicon layers is presented. Radioactive-ion implantation apparatus and a sample holder are produced for profiling operations. Atom and carrier concentration profiles are obtained by using successive layer-removal techniques which involve anodic oxidation and oxide-layer removal by hydrofluoric acid: atom concentration profiles by measuring gamma rays from radioactive impurities in the solution of hydrofluoric acid, and carrier concentration profiles from Hall-effect and sheet-resistivity measurements. This technique is applied to arsenic-ion implantation in silicon, and some results are discussed.

The measurement of electrical activity and Hall mobility of boron and phosphorus ion-implanted layers in silicon†

This paper describes an investigation into the electrical behaviour of shallow implantations of boron and phosphorus in silicon. The clover-leaf Van der Pauw patterns wore denned by planar masking techniques, and were ion implanted to produce a ‘ tailored ’ impurity profile of approximately uniform concentration with depth. It was found that phosphorus implantations became fully electrically active after annealing at a temperature between 620° c and 750° c, whereas the boron implantations required an anneal in excess of 900° c. A subsidiary activity peak, whose magnitude increased with the ion dose, was observed for the boron implantations after annealing at a temperature around 520° c.