Quality assurance in an implantation laboratory by high accuracy RBS (original) (raw)
Related papers
Accurate RBS measurement of ion implant doses in silicon
Surface and Interface Analysis, 2002
We demonstrate very accurate ion implant dose measurements using Rutherford backscattering spectrometry (RBS) traceable to a certified reference material from IRMM, Geel and the Bundesanstalt für Materialforschung (BAM), Berlin. The measurements have an absolute accuracy of better than 1.4% and a precision of better than 1.25%. The certified standard sample is compared directly with recent absolute determinations of the energy loss of He in Si, and also with a sample calibrated against the Harwell Bi standard. We determine the dose in a series of three In implants and six As implants of various doses and energies. Some of the samples were amorphized to eliminate channelling effects. A double detector geometry was used, giving pairs of spectra with a common incident charge but where the solid angle and the electronic gain were determined for each detector channel independently. The statistical uncertainty is reduced to <1%. The non-linear pileup background is determined carefully. The errors are determined critically. The experiments were carried out at different dates and different places, so time and space reproducibility of the results is confirmed. The IBA DataFurnace is used for analysis of the certified standard reference material and compared with a transparent manual data reduction method: the use of this code for routine data analysis at the highest accuracy is validated.
Certified ion implantation fluence by high accuracy RBS
The Analyst, 2015
From measurements over the last two years we have demonstrated that the charge collection system based on Faraday cups can robustly give near-1% absolute implantation fluence accuracy for our electrostatically scanned 200 kV Danfysik ion implanter, using four-point-probe mapping with a demonstrated accuracy of 2%, and accurate Rutherford backscattering spectrometry (RBS) of test implants from our quality assurance programme. The RBS is traceable to the certified reference material IRMM-ERM-EG001/BAM-L001, and involves convenient calibrations both of the electronic gain of the spectrometry system (at about 0.1% accuracy) and of the RBS beam energy (at 0.06% accuracy). We demonstrate that accurate RBS is a definitive method to determine quantity of material. It is therefore useful for certifying high quality reference standards, and is also extensible to other kinds of samples such as thin self-supporting films of pure elements. The more powerful technique of Total-IBA may inherit the...
Dose Measurements of Ultra-Shallow Implanted As and B in Si by RBS and ERD
2003
Continuous miniaturization of integrated circuits requires narrower dopant profile depth in the Si channel and consequently the use of ultra-shallow implants in the manufacturing process. Secondary Ion Mass Spectroscopy (SIMS) is routinely used to measure the boron depth concentration profiles. However, due to the altered nature of the near-surface sputtering process inherent to SIMS, it underestimates the B implanted doses for implantation energies below 2 keV. Alternate ion beam methods for absolute dose measurements of ultra-shallow implanted As and B in Si are presented in this study. The dopant implant energies ranged from 250 eV, to 5 keV for boron and from 500 eV to 5 keV for arsenic. Implanted doses for both B and As varied from 2 × 1013 to 1 × 1015 atoms/cm2. The arsenic implants were studied with Rutherford Backscattering Spectrometry (RBS) using 2 MeV carbon ions. The absolute arsenic implanted doses were measured to an accuracy of better than 5%. The 1 keV arsenic implan...
The Si surface yield as a calibration standard for RBS
Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 2000
The Rutherford backscattering spectroscopy (RBS) surface height of a pure bulk material can be used as an absolute standard value to calibrate the detector solid angle. This work presents the results of an international collaboration started at the beginning of 1998 to de®ne the surface height of the RBS spectrum H 0 of Si, amorphized by ion implantation to avoid channeling. The analyses were performed with 1±3 MeV He beams and 170°scattering angle. The detector solid angle was estimated in the dierent laboratories either by geometrical measurement or by a calibrated standard. The agreement of the experimental H 0 values is of the order AE2%, the claimed accuracy for RBS. The results are also consistent at 2% level with both the stopping power measurements of , and the measurements of . Ó
Bi-implanted silicon reference material revisited: uniformity of the remaining batch
Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 1994
A remaining batch of 65 samples of the Bi-implanted silicon reference material, issued earlier by our institution, has been investigated extensively with respect to the uniformity of the implanted Bi-layer. For this purpose long-time RBS measurements were performed in the multichannel scaling (MCS) mode. The determined non-uniformity expressed as the relative range of the bismuth fluence between its maximum and minimum values is 7%. The relative amount of the Bi fluence in individual chips as presented in this paper serves as basis to assign individual calibration values to each implanted chip. Furthermore, an estimate of the uniformity within each sample can be based upon the acquired MCS data.
Nuclear Instruments & Methods in Physics Research Section B-beam Interactions With Materials and Atoms, 2006
The concentration of 11 B + in silicon has been determined by a number of different analytical techniques. Several commercial vendors provided silicon wafers implanted with 11 B + ions over a wide range of fluence (4 · 10 13 -3 · 10 16 11 B/cm 2 ) and energy (300 eV-10 keV) for evaluation. The techniques used in this evaluation included the following: Elastic recoil detection (ERD) using 12 MeV F 4+ ions, nuclear reaction analysis (NRA) using the 11 B(p,a) 8 Be* reaction and secondary ion mass spectroscopy (SIMS). The accuracy and potential drawbacks of each of these techniques is discussed.
Range distributions of MeV implants in silicon II
Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 1987
In an earlier paper [1] range moments were presented for B, P, As and Sn implants into silicon in the energy range 0.4-6 MeV. These moments were obtained using spreading resistance profilometry (SRP) after the samples had been annealed to activate the implants. The mean of the distributions agreed moderately well with theory but the straggle was significantly greater. In this paper we present SIMS data from the as-implanted and annealed samples from the earlier study as well as SRP and SIMS data on Ga implants in silicon. The larger straggle in the annealed samples seen with SRP is also seen in the SIMS data from the annealed samples but not in the as-implanted samples. In addition, distortion of some of the profiles is evident which is probably due to channeling. In the gallium profiles particularly there is broadening of the profile on the bulk side of the implant as if diffusion in undamaged material is easier than in damaged material. This effect is only visible in annealed samples.
High-resolution depth profiling of ultrashallow boron implants in silicon using high-resolution RBS
Current Applied Physics, 2003
Depth profiles of ultralow energy (0.2-0.5 keV) B ion implants in Si(0 0 1) samples are measured by high-resolution Rutherford backscattering spectroscopy. The boron profile does not show a narrow surface concentration peak which is usually observed in the measurement of secondary ion mass spectroscopy. The obtained boron profiles roughly agree with TRIM simulation even at 0.2-keV B ion implantation.
Nuclear Instruments & Methods in Physics Research Section B-beam Interactions With Materials and Atoms, 2007
Numerous experimental studies for near-surface analyses of B in Si have shown that the B distribution within the top few nanometers is distorted by secondary ion mass spectrometry (SIMS) depth profiling with O 2-flooding or normal incidence O 2 bombardment. Furthermore, the presence of surface oxide affects the X j determination as well as B profile shape when SIMS analyses are conducted while fully oxidizing the analytical area. Nuclear techniques such as elastic recoil detection (ERD), nuclear reaction analysis (NRA), and highresolution Rutherford backscattering spectrometry (HR-RBS), are known to provide a profile shape near the surface that is free of artifacts. Comparisons with SIMS analyses have shown that SIMS analyses without fully oxidizing the analytical area agree well with these techniques at sufficiently high concentrations (where the nuclear techniques are applicable). The ability to measure both the B profile and an oxide marker with this non-oxidizing SIMS technique also allows accurate positioning of the B profile with respect to the SiO 2 /Si interface. This SIMS analysis protocol has been used to study the differences in near-surface dopant distribution for plasma-based implants. This study specifically focuses on measuring near-surface profile shapes as well as total implant doses for ultra-shallow B implants in Si especially those made with high peak B concentrations.
Monitoring of Ion Purity in High-energy Implant via RBS
Physics Procedia, 2015
The UAlbany Dynamitron is used for high-energy ion implantation as well as for routine materials analysis. Its ion source can be run using any one of fourteen different gases, leading to concerns of contamination during an implantation. The system has the usual well-calibrated mass-separation using a magnetic analyzer. A pre-or post-implant mass spectrum through this analyzer can give a useful understanding of unintended ions within the source beam, but it does not provide direct identification for such ions as CO or diatomic nitrogen-14 when implanting silicon-28. Since these possible components have the same momentum and charge (i.e. +1), the beamline mass separator will transmit them all. Because backscattered ions from the mass-separated beam will have only atomic scattering, this allows for element detection following the breakup of any molecular ion components. The verification system consists of a back-angle particle detector along with a movable temporary target consisting of a very thin film of gold on a carbon or silicon substrate. The backscattered spectrum can then be analyzed for the presence of unwanted elements. While this does not provide for removal of the unwanted components, it does provide for the identification and measurement of the problem. We show the physical layout, software and extra details necessary for successful use of the technique.