High Current Implantation Research Articles

A 40.68-MHz Active Rectifier With Cycle-Based On-/Off-Delay Compensation for High-Current Biomedical Implants

This article presents a 40.68-MHz active rectifier for high-current biomedical implants. Cycle-based timing control (CBTC) is proposed to significantly extend the duration for compensating both turn-on and turn-off delays of active diodes at 40.68 MHz, thereby improving both the power conversion efficiency (PCE) and the voltage conversion ratio (VCR) of the rectifier. The supply independent ramp, the delay-mimicking sample-and-hold (DMSH) circuit, and the low-voltage (LV)-stress startup scheme are also developed to maintain high PCE and VCR, and ensure rectifier reliability over a wide input range. Implemented in standard 0.18- <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu \text{m}$ </tex-math></inline-formula> CMOS, the proposed fully integrated rectifier delivers a maximum output power of 207 mW and operates at 40.68 MHz to enable the use of a small-diameter receiver coil of 4 mm. This rectifier is the first to achieve full turn-on and turn-off delay compensation at 40.68 MHz, so its maximum PCE and VCR obtain 86% and 96.3%, respectively. Compared with the prior art, this work not only provides more stable high PCE and VCR over a wider input range from 1.9 to 3.8 V at 40.68 MHz but also uses the smallest receiver coil for wireless power delivery.

The performance of the fourth generation of safe delivery source® (SDS®4) package on AIBT iPulsar high current implanter

The performance of the fourth generation of safe delivery source® (SDS®4) package on AIBT iPulsar high current implanter

Germanium ion implantation performance improvement on applied materials’ VIISta HCS high current implanter with use of germanium tetrafluoride (GeF4) and hydrogen (H2) mixture gases

Germanium ion implantation performance improvement on applied materials’ VIISta HCS high current implanter with use of germanium tetrafluoride (GeF4) and hydrogen (H2) mixture gases

A multipurpose set-up using keV ions for nuclear reaction analysis, high-resolution backscattering spectrometry, low-energy PIXE and in-situ irradiation experiments

A new chamber for material analysis and modification using energetic ions with primary particle energies in the keV regime was developed at the single stage 350 kV high-current Danfysik implanter at the Tandem Laboratory, Uppsala University. The experimental set-up allows for 11B and 18O depth profiling by Nuclear Reaction Analysis using the 11B(p,α0)8Be and 18O(p,α)15N nuclear resonances at 163 keV and at 151 keV, respectively. Additionally, a surface barrier detector with a cryogenic assembly enables High-Resolution Backscattering Spectrometry with average resolution ≈4 keV FWHM for protons. A silicon drift detector enables Low-Energy Particle Induced X-ray Emission analysis for elements with low atomic number (Z ≥ 8). The available instrumentation of the chamber assembly with its specifications are described in details with a series of applied and fundamental benchmark studies, together with some suggestions for future applications.

Reprint of “Low-energy high-current plasma immersion implantation of nitrogen ions in plasma of non-self-sustained arc discharge with thermionic and hollow cathodes”

This paper presents the results of low-energy high-current implantation of nitrogen ions into AISI 5140 steel. The plasma was generated using a plasma source based on non-self-sustained arc discharge, using thermionic and hollow cathodes. The influence of the temperature of the specimens and irradiation dose on the characteristics of the ion-modified layer was studied. The temperature of the specimens was controlled within the range of (450–650) °C by changing the duty factor of the bias pulse and the average ion current density. The microhardness of the steel after 1-hour of low-energy high-current implantation of nitrogen ions increased almost 2-fold (up to 7100 MPa), and a modified layer with a thickness up to 200 μm was formed. The wear resistance increased 7.5-fold. The main factor determining the efficiency of nitrogen dopant penetration was the temperature of the specimen. The parameters of the ion treatment influence the shape of the hardness distribution profile and the efficiency of ion cleaning of the surface.

Low-energy high-current plasma immersion implantation of nitrogen ions in plasma of non-self-sustained arc discharge with thermionic and hollow cathodes

This paper presents the results of low-energy high-current implantation of nitrogen ions into AISI 5140 steel. The plasma was generated using a plasma source based on non-self-sustained arc discharge, using thermionic and hollow cathodes. The influence of the temperature of the specimens and irradiation dose on the characteristics of the ion-modified layer was studied. The temperature of the specimens was controlled within the range of (450–650) °C by changing the duty factor of the bias pulse and the average ion current density. The microhardness of the steel after 1-hour of low-energy high-current implantation of nitrogen ions increased almost 2-fold (up to 7100 MPa), and a modified layer with a thickness up to 200 μm was formed. The wear resistance increased 7.5-fold. The main factor determining the efficiency of nitrogen dopant penetration was the temperature of the specimen. The parameters of the ion treatment influence the shape of the hardness distribution profile and the efficiency of ion cleaning of the surface.

Investigation of filtered vacuum arc plasma application for TiAlN and TiSiB coatings deposition using ion beam and plasma material processing

Abstract The paper studies the formation of TiAlN and TiSiB coating by macroparticle filtered vacuum arc plasma, high-frequency short-pulsed plasma immersion and repetitively pulsed high-current ion beam implantation. A new design of an axially symmetric plasma filter is described. The samples were pretreated by a repetitively pulsed high-current ion beam and plasma source “Rainbow-5” and high-frequency (100 kHz) short-pulsed (8 μs) metal plasma immersion ion surface treatment. Macroparticle-filtered metal plasma deposition was realized under ion beam mixing or using high-frequency short-pulsed negative bias. The work yields the surface morphology, elemental composition, and mechanical properties of coatings.

Improvement of the Mass Spectrometry Process on an Ion Implantation

Mass spectrometry is an essential part of ion implantation. Therefore, in order to guarantee beam purity avoiding contamination of the implanted samples, a system was developed for the high current implanter at the Laboratory of Accelerators and Radiation Technologies (LATR) at the Instituto Superior Técnico. The system presented and discussed in this paper was developed using a LabVIEW code and uses a PC to control and display the mass spectrum. It also permits to save all data acquired for posterior analysis. In order to show some capabilities of this system, some experimental results are presented.

A high-current impulse implanter

A high-current impulse implanter on the basis of a high-current ion diode with a radial magnetic field and preliminary plasma production is described. Plasma is formed at the diode anode using a negative voltage pulse that precedes an accelerating-voltage pulse. The pause between pulses is 500 ± 50 ns. Graphite is used as the emission coating on the anode. An ion beam with a current density in the diode focal plane of up to 80 A/cm2 was obtained. Analysis of the elemental composition of the ion beam using the time-of-flight technique showed that the ion beam consists mainly of С+ and С+2 carbon ions and Н+ protons.

A 13.56 MHz CMOS Active Rectifier With Switched-Offset and Compensated Biasing for Biomedical Wireless Power Transfer Systems

A full-wave active rectifier switching at 13.56 MHz with compensated bias current for a wide input range for wirelessly powered high-current biomedical implants is presented. The four diodes of a conventional passive rectifier are replaced by two cross-coupled PMOS transistors and two comparator- controlled NMOS switches to eliminate diode voltage drops such that high voltage conversion ratio and power conversion efficiency could be achieved even at low AC input amplitude |VAC|. The comparators are implemented with switched-offset biasing to compensate for the delays of active diodes and to eliminate multiple pulsing and reverse current. The proposed rectifier uses a modified CMOS peaking current source with bias current that is quasi-inversely proportional to the supply voltage to better control the reverse current over a wide AC input range (1.5 to 4 V). The rectifier was fabricated in a standard 0.35 μm CMOS N-well process with active area of 0.0651 mm(2). For the proposed rectifier measured at |VAC| = 3.0 V, the voltage conversion ratios are 0.89 and 0.93 for RL=500 Ω and 5 kΩ, respectively, and the measured power conversion efficiencies are 82.2% to 90.1% with |VAC| ranges from 1.5 to 4 V for RL=500 Ω.

Mass spectrometry improvement on an high current ion implanter

The development of accurate mass spectrometry, enabling the identification of all the ions extracted from the ion source in a high current implanter is described. The spectrometry system uses two signals ( x– y graphic), one proportional to the magnetic field ( x-axes), taken from the high-voltage potential with an optic fiber system, and the other proportional to the beam current intensity ( y-axes), taken from a beam-stop. The ion beam mass register in a mass spectrum of all the elements magnetically analyzed with the same radius and defined by a pair of analyzing slits as a function of their beam intensity is presented. The developed system uses a PC to control the displaying of the extracted beam mass spectrum, and also recording of all data acquired for posterior analysis. The operator uses a LabVIEW code that enables the interfacing between an I/O board and the ion implanter. The experimental results from an ion implantation experiment are shown.

An Efficiency-Enhanced CMOS Rectifier With Unbalanced-Biased Comparators for Transcutaneous-Powered High-Current Implants

This paper presents an efficiency-enhanced integrated full-wave CMOS rectifier for the transcutaneous power transmission in high-current biomedical implants. The comparator-controlled switches are developed to minimize the voltage drop along the conducting path while achieving the unidirectional current flow. The proposed unbalanced-biasing scheme also minimizes the reverse leakage current of the rectifier under different input amplitudes, thereby optimizing the rectifier power efficiency. Moreover, the proposed rectifier is able to self start and operates at low input amplitudes. Implemented in a standard 0.35 <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">mu</i> m CMOS process with maximum threshold voltages of |V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">thp</sub> | = 0.82 V and V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">thn</sub> = 0.69 V, the rectifier can source a maximum output current of 20 mA and operate properly with inputs of different amplitudes and frequencies. With a 1.5 MHz input of 1.2 V amplitude, the proposed rectifier can achieve the peak voltage conversion ratio of 95% and the power efficiency of at least 82%.

Charging control on high energy implanters: A process requirement demonstrated by plasma damage monitoring

Charging phenomena is one of the main problems faced in ion implantation. Anti-charging system such as plasma flood gun (PFG) are currently running on high current and medium current implanters to reduce potential charging damage on device structures. However, in a conventional production line, high energy implantation steps are still often used without any charge compensation technique. Faced with micro-arcing defects detected after Well implantation steps on production lots, we have clearly demonstrated that the defectivity issue was eradicated by enabling the PFG system on the VIISta3000 high energy implanter. In addition we have investigated charging as a function of PFG properties by plasma damage monitoring (PDM) and proved that voltages developed on oxidized wafers processed on the VIISta3000 were not insignificant.

Verification and reduction of surface charging during high/medium current implantations by implementing plasma damage monitoring

Dielectric charging damage during IC processing is the result of complex interactions between the wafer environment and the wafer itself. Understanding these interactions and recognizing the relative importance of the different mechanisms capable of causing damage, is essential for successful diagnosis and control of charging damage during wafer manufacturing. Avoiding gate oxide damage due to excessive wafer charging has always been an issue with high current implanters. Whether it is caused by shrinking of device dimensions, or its use as a backup for high current applications, charging level awareness becomes the primary limiting factor for running higher beam currents in medium current implanters. Flooding the wafer with low energy electrons from a plasma flood gun (PFG) which is a self-regulated electron shower, has been the widely accepted means of reducing wafer charging. The effectiveness of the PFG in reducing charging as a function of primary ion current, voltage of electron extraction from the PFG, ion beam positioning and other parameters in a beam path to the wafer have been investigated. This investigation was carried out on medium and high current implanters, VIISta 810HP and VIIStaHC respectively, using the plasma damage monitoring (PDM) technique on metrology tool FAaST350.

High precision 180Hf ion implantation using a high-current ion implanter

The development of accurate mass spectrometry, enabling the identification of all the ions extracted from the ion source and further precise 180Hf isotope implantation, in a high current implanter is described. The spectrometry system uses two signals ( x– y graphic), one proportional to the magnetic field ( x-axes), taken from the high-voltage potential with an optic fiber system, and the other proportional to the beam current intensity ( y-axes), taken from a beam-stop. The ion beam mass register in a mass spectrum of all the elements magnetically analyzed with the same radius and defined by a pair of analyzing slits as a function of their beam intensity is presented. Hence, it is possible to implant 180Hf +, with less than 1% contamination from neighboring isotopes, in order to conduct material characterization studies by Perturbed Angular Correlations. The precision of the low fluence ion implantation has been done by neutron activation analysis.

Device Study of Source/Drain Extension and Halo Formation Using a Single-Wafer, High-Current Implanter

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Comparison of nitrogen ion beam and plasma immersion implantation in Al5052 alloy

Experiments comparing nitrogen ion implantations in Al5052 by beam and plasma immersion were carried out. Beam implantation (BI) was carried out using a 100keV, high current beam implanter while the plasma immersion ion implantation (PIII) was obtained using a glow discharge plasma source coupled to a pulsed high voltage supply. A nitrogen BI dose of 5×1017cm−2 at 100keV was attained with near Gaussian implantation profile while the PIII was performed until we reached similar doses with a maximum energy of 15keV. Implantation profiles were obtained by Auger electron spectroscopy (AES). X-ray diffraction (XRD) indicated the formation of AlN in both cases but it was more clearly demonstrated by high resolution AES. For BI treatment, a buried AlN layer was achieved while for PIII, a layer of AlNxOy close to the surface was seen. Due to the high temperature reached in the PIII processing (400°C), a softening of the Al5052 bulk resulted while for BI processed samples with <200°C an increase in hardness was observed.

Angled implants for controlling gate–source/drain extension: A TCAD modeling study

TCAD process simulations are carried out on NMOS and PMOS to study the effect of high tilt in source/drain extension (SDE) implants and millisecond, non-melt laser anneals on junction depth and gate–SDE overlap. High tilt implants along with millisecond laser anneals are proposed as a solution for future device technology nodes (<65nm) to obtain very shallow (Xj<15nm), abrupt (<3nm/dec) junctions, with a degree of freedom to optimize gate overlap. TCAD modeling shows upon increasing the tilt angle from 0° to 30° the gate/extension overlap can increase from 2nm to over 10nm, without loss of shallow junction depth. Angled high tilt arsenic implants followed by laser anneals are also performed to study the junction depth and sheet resistance variations with tilt angle. Channeling issues at tilt angles are also analyzed and a solution based on Ge pre-amorphization is proposed to circumvent this problem. The TCAD results indicate that high tilt implant is a critical requirement on the low energy, high current implanter, and that such feature is important for controlling the gate–extension overlap with millisecond (“diffusion-light”) laser anneal technologies.

Approaches to single wafer high current ion implantation

Single wafer processing is gaining increasing market acceptance for high current ion implantation, particularly for 65nm technologies. We review the reasons for this and discuss the two competing approaches to single wafer high current implant design. These are a broad beam, single axis mechanical scan approach and a spot beam, dual axis mechanical scan approach. We compare and contrast the design complexities of each as well as their advantages and limitations.

90 nm device validation of the use of a single-wafer, high-current implanter for high tilt halo implants

As CMOS device dimensions shrink, the depths of the halo regions are shrinking and the implant doses used to form these regions are increasing to minimize short-channel effects. Shallow implant depths require lower implant energies, so the beam currents and wafer throughputs on the traditionally used medium-current implanters are starting to drop and become a concern for device manufacturers. In addition, halo implants are typically performed with a high tilt angle of 20–30° and require tight angle control. All of these requirements are leading to increased interest in use of single-wafer, high-current implanters for halo implants. This paper reports the results of a study where 90nm CMOS transistors had halo implants performed on the Applied Materials’ Quantum® X implanter. A comparison with device wafers whose halos were implanted on a medium-current implanter was also conducted. In addition, the sensitivity of the device parameters to the implant dose and angle was evaluated.