MeV Phosphorus Research Articles

The near surface damage and recovery of low nitrogen diamond implanted with MeV phosphorus ions

The purpose of this work is to provide a novel perspective for investigating the damage of diamond surfaces implanted by MeV phosphorus (P) ions and recovery of the surfaces after high-temperature annealing. SRIM simulation and low-temperature luminescence spectroscopy were performed to analyze the properties of the samples comprehensively. The results revealed that a certain degree of diamond lattice damage was caused without graphitization by the irradiation of 1 MeV P ions with a fluence value of 1015 ions/cm2. The SRIM simulation revealed that the ions that were implanted into the lattice collided with carbon atoms. These ions stopped at a depth of approximately 0.55 μm and generated intrinsic diamond defects on the diamond near the surface. The simulated defects were confirmed by the appearance of neutral single vacancy (GR1) centers in the photoluminescence (PL) spectrum after annealing at 400 °C. In addition, the annealing behavior of optical centers at 900 °C indicated significant damage recovery, including the disappearance of GR1 centers, combined with the increased intensity, slightly blue-shifted peak position, and narrowed FWHM of the nitrogen-vacancy (NV) center.

The effect of triple well implant dose on performance of NMOS transistors

The application of triple well (TW) structures provides important advantages for different types of silicon-integrated circuits. In a triple-well technology, the addition of a high energy implant allows the creation of a separate tub which is junction isolated from the substrate. We study the dependence of NMOS transistor performance and leakage current in diode test structures on the dose of a 1 MeV phosphorus TW implant. We observe that initial increase in the implant dose leads to increase in threshold voltage of the devices with a peak at a dose of about 1 /spl times/ 10/sup 14/ cm/sup -2/. With a further increase in dose the threshold voltage decreases: the decrease corresponds to the onset of Si amorphization induced by the TW implant. We explain this anomalous behavior using a model that accounts for suppression, due to formation of a buried amorphous layer, of transient enhanced diffusion of boron in the n-channel region. The dose dependence of leakage current in junction diode structures is explained by the formation of threading dislocations.

The effect of implantation, energy, and dose on extended defect formation for MeV phosphorus implanted silicon

The effect of dose and energy on postannealing defect formation, for high energy (MeV) phosphorus implanted into epitaxially grown silicon, has been studied by etch pits and transmission electron microscopy (TEM). The phosphorus dose was varied from 1×1013 to 5×1014 cm−2 and the energy was varied from 180 to 5000 keV. After implantation, the wafers were processed through subsequent annealing cycles which simulates a typical advanced complementary metal–oxide–semiconductor process to understand the formation of the defects in the near surface and projected range. For phosphorus energies above 500 keV, the threading dislocation density (TDD), increases dramatically with increasing dose from below the minimum detection limit (5×103 cm−2) at a dose of 1×1013 cm−2 to a maximum above 1×106 cm−2 for a dose of 1×1014 cm−2. However, with further increases in dose, the TDD decreases back close to the minimum detection limit. Plan-view TEM suggests that with increasing dose, the formation of extended defects at the projected range reduces the TDD. For a fixed dose of 1×1014 cm−2, the TDD exhibits a superlinear increase of nearly 3 orders of magnitude as the implant energy is increased from 180 to 2000 keV. With further increases in implant energy, the TDD saturates at a value around 2×106 cm−2. The marked effect of dose and energy on the TDD can be partially understood from homogeneous nucleation theory.

Defect clusters in high-energy ion-irradiated Ni and dilute Ni alloys investigated by diffuse X-ray scattering

Pure Ni and dilute Ni–Cu and Ni–Fe alloys were irradiated at 30 K with 150 MeV phosphorus ions up to doses of 1.6 × 10 14 and 4.1 × 10 14 ions/cm 2. The resulting defect structures were studied at room temperature using diffuse X-ray scattering (DXS) methods. The DXS experiments showed that both interstitial and vacancy dislocation loops coexisted in pure Ni and alloys. The size distribution of dislocation loops was analyzed by fitting the theoretical DXS intensities of the dislocation loops to the experimental ones.

ESR studies of high-energy phosphorus-ion implanted synthetic diamond crystals

Synthetic diamond crystals of type IIa irradiated with 9–18 MeV phosphorus ions at room temperature to fluences 4 × 10 12−4 × 10 15 ions cm −2 were studied by using electron spin resonance (ESR) technique. The degree of amorphization increasing with the fluence is manifested in the variation of the temperature dependence of the linewidth of the ESR signal of the dangling bonds. Both the ESR signal intensity and the annealing at 1800°C under 6 GPa have indicated presence of a critical fluence initiating irreversible amorphization.

Lateral range spread of MeV phosphorus ions implanted in silicon measured by time-of-flight secondary ion mass spectrometry

The range profiles of 1.0 MeV P+ implanted into silicon with a dose of 1×1015 cm−2 at angles of 7°, 45°, and 60° were measured by time-of-flight secondary ion mass spectrometry. The longitudinal and lateral range spreads at normal incidence were deduced from the measured profiles at oblique incidence. The measured profiles were systematically shallower and narrower than the TRIM’95(TRansport of Ions in Matter, 1995) predictions, but good agreement can be obtained if the electronic stopping power formula is slightly increased in the higher energy region during the calculations.

MeV heavy ion microprobe PIXE for the analysis of the materials surface

Micro PIXE analysis using MeV phosphorus microprobes was performed to a surface structure which consists of multilevel aluminum wirings in silicon nitride and these results were compared with those from a proton microprobe. In the case of a 2 MeV phosphorus microprobe, the X-ray production was enhanced near the surface due to the large energy deposition rate or the short projectile range. As a result, the increase in surface sensitivity was clearly shown in PIXE mapping images of aluminum, silicon, and phosphorus.

Single-step bandgap control in InGaAs/lnGaAlAs quantum well modulators via MeV implants

A large blue shift of the bandgap, 138 meV, in InGaAs/InGaAlAs quantum well pin modulators using a single-step MeV phosphorus ion implantation is reported. Current-voltage and photocurrent measurements show that the junction characteristic is well maintained. Moreover, we find that the blue-shifted quantum wells remain electro-optically active after implantation. Thus this technique, in addition to providing a means of producing side-by-side active and passive sections, is also promising for dual-wavelength active sections in a single quantum well wafer.

A Spreading Resistance‐Based Technique for Two‐Dimensional Carrier Profiling

A special sample preparation and measurement procedure has been developed to measure two‐dimensional carrier profiles in silicon by spreading resistance profiling (SRP) with 50 nm resolution. The raw data can be interpreted directly in terms of two‐dimensional contour lines of the junction position. Furthermore, a simulation program has been developed that allows us also to obtain the lateral diffusion profiles from the measurements. Results are shown for 20 keV boron implants, 400 keV and 1 MeV phosphorus implants as well as boron implants subjected to different annealing steps (furnace and short‐time anneal). An enhanced lateral diffusion in the initial stages of the furnace annealing has been found.

A digital signal-processing analysis technique for the infrared reflectivity characterization of ion implanted silicon

A new method for the characterization of ion-implanted silicon is proposed. It is based on analysis of the Fourier spectrum of bilinearly transformed infrared reflectance versus wavenumber data of ion-implanted samples. This non-destructive technique has been applied to previously published infrared reflectance data of 〈111〉 and 〈100〉 oriented Si samples which had been implanted with 2.7 MeV phosphorus and 380 keV silicon ions, respectively, and annealed at 500° C for various lengths of time. The refractive index and thickness of the amorphous layer of the as-implanted samples can be measured directly by means of this technique. The position of boundaries between the amorphous, recrystallized and substrate zones, as well as the position of the carrier concentration peak can be determined for the various annealing times. Depending on the annealing time, the recrystallized layer in 〈111〉 silicon has a refractive index which is between 2% and 4% higher than the substrate refractive index, while the difference in refractive index between the amorphous and recrystallized layers is in the order of 5%. In contrast to these results, the presence of the substrate/recrystallized material interface could not be detected in partially recrystallized 〈100〉 silicon by this method, implying that the refractive index step at the substrate/recrystallized material interface is less than 1%. The step in refractive index at the crystalline/amorphous interface in 〈100〉 silicon implanted with a dose of 0.5 x 1016 cm−2 silicon ions, was measured to be 12%, and it is reduced to 8% after partial regrowth has occurred. These results confirm the data obtained by a model-based least-squares analysis.

Average stopping powers and the use of non-analyte spiking for the determination of phosphorus and sodium by PIPPS

Using particle induced prompt photon spectrometry, PIPPS, the ratos of the average stopping powers in samples and standards can be used to determine elemental compositions. Spiking the sample with a known amount of a non-analyte (lithium) compound with known stopping power, appropriate stopping powers in the samples can be determined by measuring the prompt gamma-ray yields induced in the spike. Using 5 MeV protons sodium and phosphorus were determined in ivory, while sodium was determined in geological samples. The method was tested by analyzing the standard reference materials SRM 91, 120c and 694.

Distribution of paramagnetic defects formed in silicon by MeV ion implantations

Two different types of paramagnetic centers in silicon, Si-P3 (neutral {110} planar tetravacancies) in a well defined crystalline structure and point defects with poorly defined local structure in substantially damaged crystalline environments, formed by 3 MeV phosphorus and silicon ion implantations up to a dose of 1 × 10 14 cm −2 have been compared both in the dose dependence of area densities and in depth profiles. When the dose reaches to 1 × 10 14 cm −2, the area density of Si-P3 starts to saturate while that of “indefinite” point defects keeps increasing. Also at this dose, the mean concentration of Si-P3 decreases as a function of depth from the surface whereas that of “indefinite” point defects increases. These results are discussed in terms of a damage overlap model in conjunction with a Monte Carlo simulation of lattice disorder.

Thermal wave characterization of silicon implanted with MeV phosphorus ions

We have performed laser-induced photothermal reflectance measurements on p-type (100) silicon wafers implanted with phosphorus in the energy range of 0.5 to 3 MeV. The dose for implants was varied from 1 × 10 12 to 1 × 10 14 ions/cm 2. The variation of thermal wave signal for different implant angles and species has been studied. The signal was sensitive to the dose, energy and tilt angle of the implantation. We have determined that this technique can be used to monitor high energy implantations into Si substrates.

Ranges, straggling and carrier concentration profiles of 0.5–6.0 MeV phosphorus in silicon

Using an lonex Company 2×1.7 MeV Tandem experiments were conducted to obtain a more detailed knowledge of ranges, straggling and carrier concentration profile for P + implanted into P-type (111) Si at 0.5–6.0 MeV to doses ranging from 4×10 12 to 1×10 13 cm −2. The annealing of the samples was carried out by Rapid Thermal Annealing (RTA) at 1000–1050°C for 10 s to achieve a high electrical activation and small spreading. The carrier concentration profiles were measured by Spreading Resistance Probe (SRP). It is found that the profiles are two joined half-Gaussian distribution with different standard deviations σ front and σ back. σ front is greater than σ back. The buried layers of N-type carrier appear when the P + energy is higher than 3.0 MeV. The ranges and straggling of 0.5–6.0 MeV P + implantation in Si have been obtained, but the values of measured ranges are less than that of the theoretical values. Some characteristics of the high energy P + implantation in Si are discussed.

Carrier concentration profiles in multiply implanted silicon with 0.5–7.5 MeV phosphorus

MeV implantation is very important in fabricating semiconductor devices and VLSI. The carrier concentration profiles in high energy phosphorus implanted silicon have been investigated. Phosphorus with energies ranging from 0.5 to 7.5 MeV were implanted into Si with doses ranging from 2 × 10 12 to 1 × 10 13/cm 2. The results indicate that carrier concentration profiles consist of two half-Gaussians distribution with different stragglings σ f and σ b. According to these profiles the method of forming a uniform profile with multiple implantations was suggested. The various specific carrier concentration profiles can be got by multiple implantations with different energies, doses and masking technology with SiO 2. Rapid thermal annealing has been used to obtain good reliability and reproducibility of their profiles. The residual defects of the samples were measured by 1000 kV TEM. Specific transistors produced with phosphorus multiple implantations have satisfactory characteristics.

Depth Profile of Neutral Planar Tetravacancies in 3 MeV Phosphorus Implanted Silicon as Studied by EPR

Depth Profile of Neutral Planar Tetravacancies in 3 MeV Phosphorus Implanted Silicon as Studied by EPR

Range and range profile calculations for MeV phosphorus implantation into silicon

The available experimental range and range profiles are compared with theoretical predictions based on different models for the electronic stopping cross-section. Implantation energies from 0.1 to 10 MeV are considered. In the entire energy range, the best agreement between the experimental data and the calculations is achieved for a combination of the Lindhard-Scharff and the Bethe-Bloch electronic stopping formulae using the empirical parameter C k = 1.2 .

Profile studies of MeV ions implanted into Si

Experimental profile data for MeV arsenic, phosphorus and boron ions implanted into silicon are presented. The energy ranges are 3–11 MeV, 1–7 MeV and 1–4 MeV for arsenic, phosphorus and boron respectively. Profiles are obtained from secondary ion mass spectroscopy (SIMS). To make the profile data easily accessible in integrated circuit processing design, moments parameters are extracted and fitted into profile models. The R p, ΔR p, skewness and kurtosis of the measured data were fitted by polynomials to facilitate convenient calculations for process simulators. It is found that MeV arsenic, phosphorus and boron profiles can all be adequately modeled by Pearson-IV distribution functions, while Gaussians result in large errors in the tail portions of the profiles.

High energy implantation and annealing of phosphorus in silicon

The properties of silicon single crystals after 1 MeV phosphorus implantation with doses in the range of 5 × 10 11 to 7.5 × 10 14 cm −2 - and annealed by different methods are investigated. The ion range is about 1 Am. A good agreement between the experimental profiles and theoretical ones calculated using a modified TRIM code is stated considering the Brandt-Kitagawa theory for the electronic stopping power. In the as-implanted state no amorphization is observed for a dose of 7.5 × 10 14 cm −2 although nuclear energy deposition was above the theoretical amorphization threshold. Spreading resistance measurements indicate that the radiation damage extends up to a dose-dependent depth between 1.8 and 6 μm. After annealing, a defect band of dislocations and stacking faults is formed at about R max . By C-t measurements of the low dose sample a defect peak slightly behind the maximum of the ion profile is detected. Spreading resistance measurements show that the deep tail of radiation damage is not completely removed by the investigated annealing treatments.

On the effects of implantation of ions in the MeV energy range into silicon

The effects of MeV phosphorus implantation and subsequent process steps on the electrical characteristics of p-channel field-effect transistors (FET), Schottky barrier diodes and p- n junctions were studied. The observed I– V characteristics can be explained in terms of spatially localized defects induced by the high-energy implantation and correlate well with the results using Monte Carlo simulation and C– V profiling techniques.