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Ion Implantation Technology, 2000. Conference on

Date 17-22 Sept. 2000

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  • 2000 International Conference on Ion Implantation Technology Proceedings. Ion Implantation Technology - 2000 (Cat. No.00EX432)

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  • Gate oxide damage due to through the gate implantation in MOS-structures with ultrathin and standard oxides

    Page(s): 103 - 106
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    For characterization of oxide damage created by through the gate implantation (TGI) of boron, we prepared samples that allowed us to investigate reliability degradation and intrinsic electron trap density. Constant current stress measurements show a strong dependence of gate oxide reliability on TGI dose for oxide thickness down to 4.0 nm. An additional thermal treatment can anneal TGI induced damage to some extent. Based on our experimental results, we discuss possible extensions to common oxide breakdown models assuming an additional intrinsic electron trap density or an enhancement of electron trap generation rate, respectively. View full abstract»

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  • Computer simulation of ion implantation at grazing ion-surface interactions

    Page(s): 232 - 234
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    The peculiarities of ion implantation into the one-component and binary crystal surface under conditions of low-energy ion bombardment at grazing incidence have been investigated by computer simulation. The depth distributions of 5 keV Ar ions implanted into Cu(001) surface and 1 keV Be and Se ions implanted into GaAs(001) for a range of grazing angles of incidence (3-30°) have been calculated and presented View full abstract»

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  • Arsenic clustering and precipitation analysis in ion-implanted Si wafers by X-ray absorption spectroscopy and SIMS

    Page(s): 600 - 603
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    EXAFS and SIMS have been used to obtain clustering and precipitation information in As (arsenic) implanted Si wafers. CZ(001) Si wafers were first implanted by As at 100 keV to a dose of 1×10 15/cm2 followed by a second As+ implantation at 20-30 keV with doses of 1×1015/cm2 -1×1018/cm2. From the SIMS concentration depth profiles and the corresponding UT-MARLOWE simulations, the region where the As-concentration is above the solid solubility level was determined. The coordination numbers (N) and the nearest-neighbor distances (R) to As atoms in the first shell were extracted from Fourier analysis of the EXAFS data. When arsenic precipitates as monoclinic SiAs, the nearest neighbor distances and coordination numbers are ~2.36 and ~3, as opposed to ~2.40 and ~4 when As is substitutional. Based on this information, the critical implant dose where the precipitation of As starts, and the ratio of the substitutional to precipitate As in the samples was determined View full abstract»

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  • Author index

    Page(s): 825 - 829
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    Freely Available from IEEE
  • Enhancing B+ ion current by adding MgO to the chamber material of a microwave ion source

    Page(s): 520 - 523
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    It is experimentally shown that increasing the electron-emission coefficient of the chamber material can enhance B+ ion current from a microwave ion source. The plasma potential dependence on the coefficient is theoretically studied. As the preliminary test, the potential differences between the chamber wall and a test surface with different coefficient of the electron emission and it is proved that the potential is lowered by coating MgO on the test surface. Then we tested some chambers with different amounts of MgO added to by installing them in the microwave ion source, which was mounted on a commercial beam line of Applied Materials xR80. The result obtained so far shows that B+ ion current is considerably enhanced with the chamber of 5% MgO View full abstract»

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  • Modifications to improve lifetime of the ELS ion source

    Page(s): 524 - 526
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    The Extended Life Source, ELS, generally provides improved source life compared to the more commonly used Bernas source. The ELS source uses an indirectly heated cathode to keep the filament out of the arc chamber. Typical lifetime for NV-GSD sources running a mix of species in production has been about 100 to 300 hrs. Failure has often been associated with the cathode insulation, filament failures, or filament shorts. A new cathode assembly is discussed, which has allowed the source life to exceed 1300 hrs in production use on a NV-GSD/HE. Multiple-charged species are more challenging to produce and require high arc power to achieve useable currents. Requirements for 100 μA of He++ with a source life of at Least 100 hrs on the Axcelis 8250 implanter necessitated a factor of two increase in source life. A special ELS source was developed which uses a thicker cathode, tungsten repeller, and other modifications to tolerate high arc power to enhance He++ current. These modifications and their effect on performance is described View full abstract»

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  • Decaborane ion implantation

    Page(s): 304 - 307
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    The continued scaling of integrated circuit devices has resulted in the need for lower and lower implant energy capabilities. The difficulties associated with extraction and transport of low energy beams have lead to research in novel techniques for ultra low energy implantation. Results from one such technique, decaborane ion implantation, are reported here. Decaborane is a molecule with 10 boron atoms that has been proposed as an implant feed material to overcome the low energy beam problems. Decaborane implants into 200 mm wafers were performed for the first time using an Eaton high current implanter. High-resolution beam spectra that reveal the details of a decaborane ion beam are shown. Data from the implanted wafers will be compared with data from reference boron implanted wafers performed on an Eaton ULE2 ion implanter. The comparison includes surface resistivity maps and SIMS profiles at 500 eV equivalent energy and demonstrates equivalence between the two implantation methods. We will also present transistor data from devices fabricated with decaborane implants View full abstract»

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  • Ion beam induced strain relaxation in pseudomorphous epitaxial SiGe layers

    Page(s): 70 - 72
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    The effects of irradiation with Ge+ and Ar+ ions at elevated temperatures on the relaxation behavior of pseudomorphic Si0.79Ge0.21/Si heterostructures have been compared. It was found the strain relaxation in the structures implanted with Ge+ at 400°C started already upon implantation, post-implantation thermal annealing of this sample resulted in considerably higher degree of relaxation than that in control (non-implanted) samples as well as in samples implanted with Ar + both at 230 and 4000°C and with Ge+ at 230°C. This result points to a dramatic influence of both the implantation temperature and ion species on relaxation behavior of the ion-irradiated heterostructure. Two possible mechanisms for this effect are discussed View full abstract»

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  • In-line characterization of preamorphous implants (PAI)

    Page(s): 635 - 638
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    Amorphous layers formed with Ge implantation into Si over a range of energy (5 to 70 keV) and dose (0.5 to 3×1015/cm2) were characterized using carrier illumination (CI), variable angle spectroscopic ellipsometry (VASE), and cross-sectional transmission electron microscopy (XTEM). The CI signal varies lineariy with XTEM depth to 860 Å. The VASE response is monotonic, and can be linearized with additional calibration. Both methods are sensitive to amorphous layer depth and exhibit no dose sensitivity. CI is additionally sensitive to depth differences between 0° to 7° implant angles View full abstract»

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  • Formation of the electrically active centres in silicon irradiated with high energy ions and annealed at temperatures of 350-1050°C

    Page(s): 115 - 118
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    Three groups of electrically active centers were observed in silicon implanted with high energy ions and annealed in a wide temperature range. The first centers are thermal donors enhance formed in the temperature range of 380-500°C. The second ones are shallow acceptors observed in the temperature range of 500-570°C. The last ones are most likely “new” thermal donors introduced in high concentration after annealing at 600-1050°C. Depth distributions of the centers and-the reasons of their effective formation are discussed View full abstract»

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  • Steady-state, direct-current (DC) plasma immersion ion implantation (PIII) for planar samples

    Page(s): 515 - 519
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    A new direct current (DC) plasma immersion ion implantation (PIII) technique by using a grounded conduction grid positioned between the plasma source and sample chuck is described in this paper. DC-PIII is simulated employing the particle-in-cell (PIC) method. Our simulation shows that the ion paths do not change with the negative voltage applied to the wafer stage as well as the mass and charge states of the ions. The ion dose and impact energy uniformity is determined by the internal ratio between the r (radius of sample platen), R (radius of vacuum chamber), H (distance between the grid and bottom of the vacuum chamber), and D (thickness of sample platen). Our simulation suggests that the best ratio is r:R:H:D=1:4:2.5:2. Our experimental results show that high voltage DC-PIII can be realized by using a conducting grid in a conventional PIII system View full abstract»

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  • Parallel Monte Carlo simulation of ion implantation

    Page(s): 203 - 208
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    An efficient parallelization method based on MPI (Message Passing Interface) for a Monte Carlo program for two-dimensional and three-dimensional simulation of ion implantations is presented. The method is based on a master-slave strategy where the master process synchronizes the slaves and performs the I/O-operations, while the slaves perform the physical simulation. For this method the simulation domain is geometrically distributed among several CPUs which have to exchange only very few information during the simulation. Thereby the communication overhead between the CPUs is kept so low that it has almost no influence on the performance gain even if a standard network of workstations is used instead of a massively parallel computer to perform the simulation. The performance gain has been optimized by identifying bottlenecks of this strategy when it is applied to arbitrary geometries consisting of various materials. For that reason different physical models within the simulation domain must be applied why it is impossible to determine a reasonable domain distribution before starting the simulation. Due to a feedback between master and slaves by on line performance measurements, we obtain an almost linear performance gain on a cluster of workstations with just slightly varying processor loads. Besides the increase in performance the parallelization method also achieves a distribution of the required memory. This allows three-dimensional simulations on a cluster of workstations, where each single machines would not have enough memory to perform the simulation on its own View full abstract»

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  • Energy dependence of low dose SIMOX wafers

    Page(s): 277 - 280
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    SIMOX (separation by implantation of oxygen) is one of leading methods to synthesize SOI (silicon on insulator) wafers. Low-dose implantation is a growing interest method nowadays for the fabrication of SIMOX wafers since it shows great advantages such as high yield, high thermal conductivity and stronger radiation hardening compared to conventional standard full dose implantation. In this paper, we reported the formation of SIMOX-SOI at acceleration energies ranging from 160 to 100 KeV with doses of 4.5 and 5.5×1017 cm-2, and consequently annealed at high temperature of 1324°C in Argon+Oxygen atmosphere for 5 hours. The evolution of low-dose SIMOX wafers was characterized by RBS, XTEM, HRTEM and Secco, respectively. The results indicate that the optimum dose-energy window plays an important role for the formation of high quality SIMOX wafers with good crystals of top silicon, sharp Si/SiO2 interface, high integrated buried oxide layer with minimum silicon island density View full abstract»

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  • Low and high dose process monitoring using the BX-10 implant monitor system

    Page(s): 639 - 641
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    The Boxer Cross BX-10 metrology tool was developed to provide in-line nondestructive measurement of critical ultra-shallow junction processes for sub-0.18 micron devices. Most of the experimental work to date has been on the use of the BX-10 to provide shallow junction depth measurements on annealed implants. However, capability has been demonstrated for the BX-10 to measure low dose and high dose process monitor wafers, and the ability of the BX-10 to provide implant monitoring supplements its role as an in-line junction depth monitor. This paper evaluates the statistical process capability of the BX-10 for monitoring low dose implants on nonannealed wafers and high dose implants on annealed wafers View full abstract»

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  • Increased ion source life for Varian's kestrel implanter

    Page(s): 538 - 541
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    In an effort to extend the longevity of the Bernas source on Varian's MeV implanters, the effect on source life of increasing the diameter of the extraction aperture was studied. For a given beam current, plasma density is inversely proportional to the aperture area. Since source life is inversely proportional to plasma density, it should, then increase linearly with the aperture area. Two diameters were investigated: one with 40% more area, and one with twice the area. Extraction was modeled using KOBRA, and then tested. An observation made from tests indicated that the gas flow required to maintain a stable arc was found to increase precipitously with the larger aperture; therefore attention was restricted to the first one. Results from the tests also showed that the required arc power to produce spec beam was reduced by about 40%, as expected, and transmission through the Tandetron was unaffected. A series of source life tests were then conducted, with a 50/50 mix of phosphine and boron. Results showed the expected 40% increase. Finally some of the tests were performed with a tungsten arc chamber to evaluate tungsten filament re-growth (“halogen effect”) on source life View full abstract»

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  • Advantages of the varian VIISta single wafer high current ion implanter for advanced device fabrication

    Page(s): 431 - 434
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    Advanced IC designs are demanding a new level of performance and flexibility from the next generation of ion implanters. In addition to beamline improvements for charge control, energy contamination, metals and cross contamination, the industry is also experiencing a new requirement with the emergence of Large Angle Tilt Implants (LATI, 10-60 degrees). LATI can be employed to overcome Short Channel Effects (SCE) by the use of Halo/Pocket implants and more recently, for the control of gate overlap with SDE implants. This paper describes the beamline characteristics of the VSTIIa 80 single wafer high current implanter, from the standpoints of overall defect control and the tools ability to provide large angle tilt capability to address the needs of advanced scaled devices View full abstract»

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  • Decaborane ion source demonstration

    Page(s): 527 - 529
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    This project demonstrated concept and feasibility of a proprietary high current decaborane ion source suitable for ultra shallow doping. This was motivated by the attractive scaling of decaborane ions for space charge dominated extraction and transport. A highly modified Bernas source was mounted on an NV-10/80 implanter. Using standard extraction and beamline components, 2.3 mA of boron nucleon current was produced in the form of B14Hx+ at 50 kV. Under dense plasma, beam current scaled linearly with extraction voltage View full abstract»

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  • Novel aspects of the atomic transport of B implanted in silicon at energies below 1 keV

    Page(s): 163 - 166
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    The non equilibrium diffusion of ultra-low energy B ions implanted into Si is characterized by an ultra-fast process, occurring during the ramp-up of the thermal process and by a transient enhancement of the diffusion with an activation energy of 1.7 eV. We have also investigated the location of the defects causing the transient enhanced diffusion. The fast and ultrafast processes are found to be generated by defects located at different depths. The defects responsible for the fast tail shift are located closer to the surface than the defects leading to the ultrafast tail shift View full abstract»

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  • Modeling of implanted ion distribution in AIIIBV semiconductors

    Page(s): 243 - 246
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    The depth distribution of Be and Se atoms after the implantation and annealing processes into compounds AIIIBV have been determined using the SIMS technique. The results are compared with the respective computer simulation View full abstract»

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  • SIMS quantification round-robin study at Evans analytical group

    Page(s): 631 - 634
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    Bulk-doped silicon wafers were measured at four EAG (Evans Analytical Group) site laboratories in a round-robin study of the calibration of SIMS measurements of dopant concentrations in silicon. Mean B, P, and As concentrations were determined for several bulk-doped silicon reference wafers. Absolute concentration calibration scales are determined by NIST Standard Reference Materials (B, As) or accepted Consensus Reference Materials (P). At any single EAG measurement site, the average repeatibility of an individual dopant concentration measurement was about 0.7% for B, 2.1% for P, and 2.3% for As. Across the four sites, the best reproducibility for concentration measurements was found when bulk-doped standards were used for calibration. Average reproducibility of dopant concentration measurements across the EAG was 0.9% for B, 2.5% for P, and 2.6% for As View full abstract»

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  • Achieving next generation performance of ion implanters with the Varian Control System (VCS)

    Page(s): 419 - 422
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    This paper addresses the practical realization of a complex hierarchical control system, which is able to maintain controllability and observability conditions in a fault tolerant manner for a variety of ion implanters as well as other related systems View full abstract»

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  • Doping of the poly-gate by beamline implantation and plasma doping and its influence on the gate oxide reliability

    Page(s): 308 - 311
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    During the ion implantation process, it is well known that the ion beam induces at the wafer surface a potential, which is at the origin of charging effects. We used MOS capacitors with a gate oxide thickness of 4 nm and a polysilicon gate doped by implantation of P for the n+ gate and by B or BF2 for the p+ gate. The MOS structures were electrically tested by means of charge-to-breakdown (Qbd), capacitance-voltage (C-V) and current voltage (I-V) characteristics. It is shown that the Qbd is significantly sensitive to the charging effects and thus can be used to investigate the oxide degradation during the ion implantation. For the P and B implants, the use of a plasma food gun (PFG) neutralization system reduces drastically the degradation of the gate oxide. However, for BF2 implants we observed a strong degradation of the gate oxide when using the PFG. We demonstrated, for the first time, that this degradation is mainly due to the charging rather than the fluorine incorporation in the gate oxide, as often suggested in the open literature. In the BF2 case, we also evidenced a fluorine-induced shift in the C-V plots. This shift corresponds to a high (2×1012 cm-2) negative charge density in the gate oxide. The charging effects and thus the oxide degradation are found to depend on the beam current and energy. We suggest a qualitative model, based on the yield of secondary electron emission, to interpret the observed trends View full abstract»

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  • Ion implantation of N into Si and SiO2/Si in the 1-1000 eV energy range for gate dielectric fabrication

    Page(s): 342 - 345
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    We report on N doses and profiles in Si and in ultrathin SiO2 films on Si nitrided by plasma or ion beam processing in the 1-1000 eV energy range. Accurate elemental quantification was performed by nuclear reaction analysis, and elemental profiling with subnanometric depth resolution was achieved by narrow nuclear resonance profiling or medium energy ion scattering. Heavy and shallow N incorporation was observed, with up to 0.7 N/(N+O) and peak N concentrations at 2 nm and less from sample surface. Device-quality films were produced with post-nitridation annealing in O2, as indicated by C-V and I-V measurements View full abstract»

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  • XTEM study of Ni gettering to H-implantation-induced nanocavities in SIMOX

    Page(s): 281 - 284
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    Nanocavities were generated in the silicon substrate of the SIMOX wafer by H implantation and annealing. Different dose of Ni impurities were introduced in the Si overlayer by implantation. The structures of nickel decorated voids and Ni precipitates epitaxially grown in the void band were studied. NiSi2 precipitates were observed both in the nanocavities and at the residual defects created by H implantation. The microstructure of Ni precipitate depended on whether there were voids nearby. Without cavities in the vicinity, dislocations were observed in the neighborhood of the precipitate, whereas no dislocation was detected around the precipitate when there are many nanocavities in the neighborhood. Due to the competitive gettering effect of BOX, the gettering efficiency of Ni to nanocavities in SIMOX is lower than that in bulk Si View full abstract»

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