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Journal of Materials Science Letters 01/2002; 21(20):1611-1614.
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ABSTRACT: A novel plasma implantation technique performed in a low pressure steady state dc mode utilizing a grounded conducting grid on top of the wafer stage is presented. By numerically simulating the ion paths by the particle-in-cell method, it is observed that the ion paths are optimized for certain implant geometry. In the optimal configuration, the directional angle of the acceleration vector does not depend on the mass and charge state of the ions, and the ratio of the partial differential of the scalar potential ϕ along the radial and longitudinal directions remains constant for varying applied voltages. The retained dose and impact energy uniformity are totally determined by the ratio of the radius of the wafer stage r, radius of the vacuum chamber R, distance between the wafer stage and the grid H, and thickness of the wafer stage D. The optimal ratio is r:R:H:D=1:4:2.5:2, that is, suggesting a disk shape vacuum chamber, which is quite different from that of a conventional plasma immersion ion implanter. In addition to retaining the large area and parallel processing advantages of plasma immersion ion implantation (PIII), the implantation energy can be extended far beyond the limit of PIII as the technique obviates the use of the power modulator, which not only limits the implantation energy but also is the most expensive and technologically complex hardware component in a PIII system. © 2000 American Institute of Physics.
Journal of Applied Physics 04/2000; 87(9):4094-4097. · 2.17 Impact Factor
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ABSTRACT: 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
Ion Implantation Technology, 2000. Conference on; 02/2000
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Journal of Materials Science Letters 01/2000; 19(21):1883-1885.
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ABSTRACT: Microcavities or bubbles formed by hydrogen and helium plasma
immersion ion implantation (PIII) possess many interesting properties.
For instance, they emit light similar to porous silicon, but since they
are buried, the optical properties are not affected by surface
conditions such as those encountered by conventional porous silicon
materials. These bubbles also form excellent internal gettering sites
for metal impurities and are stable even at high temperature. Last but
not least, the ion-cut/bonding technology utilizing the stress created
by these microcavities to achieve thin film transfer is used to
fabricate silicon-on-insulator (SOI)
Ion Implantation Technology Proceedings, 1998 International Conference on; 01/2000
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ABSTRACT: The effect of plasma immersion ion implantation (PIII) treatment on silicone surfaces was investigated by x-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR-ATR), and scanning electron microscopy (SEM). Low-energy (at voltages of 4 and 8 kV) and high-fluence (8 × 10 17 cm −2) implantation of nitrogen was performed using an inductively coupled plasma source (ICP) at low pressure (∼0.03 Pa). The IR absorption spectra showed a significant decomposition in the CH 3 , Si–CH 3 , and C–F groups of the silicone surface after PIII treatment. The percentage of decomposition was dependent on the implantation energy. The XPS C 1s spectra of the PIII modified surfaces showed an increase in the polar carboxyl (O–C=O) groups and a decrease in the CF 3 groups. PIII treatment shifted the XPS Si 2p peak of silicone to a higher binding energy (around 103.2 eV) and the N 1s peak to lower binding energy (around 398.5 eV). The modified Si 2p, N 1s, and O 1s spectra suggest the formation of SiO x phases, silicon oxynitrides, and silicon nitrides on the silicone surface after PIII treatment.
J. Phys. D: Appl. Phys. 01/2000; 33:2869-2874.
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ABSTRACT: Hydrogen plasma immersion ion implantation into a 200-mm-diam silicon wafer placed on top of a cylindrical stage has been numerically simulated by the particle-in-cell (PIC) and transport-and-mixing-from-ion-irradiation (TAMIX) methods. The PIC simulation is conducted based on the plasma comprising three hydrogen species H+, H2+, and H3+ in a ratio determined by secondary ion mass spectrometry. The local sputtering losses and retained doses are calculated by the Monte Carlo code TAMIX. The combined effect of the three species results in a maximum retained dose variation of 11.6% along the radial direction of the wafer, although the implanted dose variation derived by PIC is higher at 21.5%. Our results suggest that the retained dose variations due to off-normal incident ions can partially compensate for variations in incident dose dictated by plasma sheath conditions. The depth profile becomes shallower toward the edge of the wafer. Our results indicate that it is about 34% shallower at the edge, but within a radius of 6.375 cm, the depth of the peak only varies by about 5%. For plasma implantation process design, a combination of PIC and TAMIX is better than the traditional practice of using PIC alone. © 1999 American Institute of Physics.
Journal of Applied Physics 08/1999; 86(4):1817-1821. · 2.17 Impact Factor
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ABSTRACT: A pseudo two-dimensional (2-D) analytical model and a 2-D plasma
simulator PDP2 code have been utilized to characterize ion-matrix sheath
and dynamic sheath expansion during the plasma immersion ion
implantation process. The pseudo 2-D model is very simple by involving
two geometry factors and yields an acceptable accuracy under the current
process conditions. Good agreement between the pseudo 2-D model and PDP2
simulation was observed
IEEE Transactions on Plasma Science 07/1999; · 1.17 Impact Factor
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ABSTRACT: Summary form only given. Silicon-on insulator (SOI) is an attractive material compared with bulk silicon substrate for high speed, low power, low voltage complementary metal oxide semiconductor (CMOS) integrated circuits. A bond-cut process, commercially referred to as Smart-Cut<sup>TM</sup> developed by SOITEC, has provided excellent SOI wafers. One of the critical steps of Smart-Cut is to implant a fairly high dose of hydrogen into the wafer to form a plane along which the wafer can crack. Conventional beam-line ion implantation can be replaced by plasma immersion ion implantation (PIII) to achieve a higher throughput and lower cost. For hydrogen PIII/bond-cut, the coexistence of H<sup>+</sup>, H<sub>2</sub><sup>+</sup>, and H<sub>3</sub><sup>+ </sup> in the plasma tends to spread the implanted hydrogen profile that cracking may not occur uniformly. Hydrogen plasma immersion ion implantation (PIII) into a 200 mm diameter silicon wafer placed on top of a cylindrical stage has been numerically simulated by the particle-in-cell (PIC) method. The plasma consists of three hydrogen species H<sup>+</sup>, H<sub>2</sub><sup>+</sup>, and H<sub>3</sub><sup>+</sup> in different ratios. The retained dose and sputtering loss are calculated by TAMIX
Plasma Science, 1999. ICOPS '99. IEEE Conference Record - Abstracts. 1999 IEEE International Conference on; 02/1999
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ABSTRACT: Mono-energetic plasma immersion ion implantation (PIII) into
silicon can be attained only under collisionless plasma conditions. In
order to reduce the current load on the high voltage power supply and
modulator and sample heating caused by implanted ions, the plasma
pressure must be kept low (<1 mtorr). Low pressure PIII is therefore
the preferred technique for silicon PIII processing such as the
formation of silicon on insulator. Using our model, we simulate the
characteristics of low pressure PIII and identify the proper process
windows of hydrogen PIII for the ion-cut process. Experiments are
conducted to investigate details in three of the most important
parameters in low pressure PIII: pulse width, voltage, and gas pressure.
We also study the case of an infinitely long pulse, that is, dc PIII
IEEE Transactions on Plasma Science 01/1999; · 1.17 Impact Factor
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ABSTRACT: In spite of recent progress on plasma immersion ion implantation
(PIII) in semiconductor processing, for example, formation of silicon on
insulator and shallow junctions, ion dose, and energy uniformity remains
a major concern. We have recently discovered that the sample stage
(chuck) design can impact ion uniformity significantly. Using a
theoretical model, we have investigated three different chuck designs
and conclude that insulators on the stage can alter the adjacent
electric field and ion trajectories. Even though the conventional stage
design incorporating a quartz shroud reduces the load on the power
supply and contamination, it yields ion dose and energy nonuniformity
unacceptable to the semiconductor industry. Thus, for semiconductor
applications, the stage should be made of a conductor, preferably
silicon or silicon coated materials and free of quartz
IEEE Transactions on Plasma Science 01/1999; · 1.17 Impact Factor
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ABSTRACT: High dose-rate plasma ion implantation (PII) has been utilized to produce low dielectric constant (k) SiO/sub 2/ films for high quality interlayer dielectrics. The SiO/sub 2/ films are fluorine-doped/carbon-doped by PII with CF/sub 4/ plasma in an inductively-coupled plasma (ICP) reactor. It is found that the use of CF/sub 4/ doping results in exceptional dielectric properties which differ significantly from fluorinated SiO/sub 2/. The dielectric constant of the SiO/sub 2/ film is reduced from 4.1 to 3.5 after 5 minute PII, other electrical parameters such as bulk resistivity and dielectric breakdown strength are also improved.
IEEE Electron Device Letters 12/1998; · 2.85 Impact Factor
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ABSTRACT: Plasma immersion ion implantation has been demonstrated to be a viable technique for microelectronics processing such as fabrication of shallow junction and silicon on insulator. However, a wider acceptance of this fledgling technology by the semiconductor industry is not possible unless the stringent dose and energy uniformity requirements can be met. We have recently discovered that the lateral dose and energy nonuniformity that is unacceptable to the silicon industry stems from the insulating shroud commonly used around the sample stage to reduce the current demand on the power supply. We have developed a theoretical model to explain the experimental results. The model can also be used to optimize the operating conditions and equipment design to achieve the desired dose and energy uniformity across a planar silicon wafer to satisfy the semiconductor industry. © 1998 American Institute of Physics.
Applied Physics Letters 07/1998; 73(2):202-204. · 3.84 Impact Factor
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ABSTRACT: Defect passivation in polycrystalline silicon (poly-Si) CMOS
thin-film transistors (TFT's) has been performed by plasma ion
implantation (PII) hydrogenation process. Implantation at low energy (2
keV) and high dose rate(~10<sup>16</sup>/cm<sup>2</sup> S) was achieved
by an inductively-coupled plasma source. The device parameter
improvements are saturated in 3-4 min, which is much shorter than other
hydrogenation methods reported in the literature. The stress
measurements indicate that the devices hydrogenated by this new
technique have much better long-term reliability than that hydrogenated
by other techniques
IEEE Transactions on Electron Devices 07/1998; · 2.32 Impact Factor
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ABSTRACT: Plasma immersion ion implantation (PIII) has recently been shown
to be a viable method to fabricate silicon-on-insulator (SOI) materials
using either the SPIMOX (separation by plasma implantation of oxygen) or
the ion cut/wafer bonding method. We have recently modified and
characterized a new generation plasma immersion ion implanter for SOI
fabrication, and this paper will discuss some of the instrumental and
processing issues, including the plasma source, mean free path
consideration, and dc sheath characteristics
IEEE Transactions on Plasma Science 03/1998; · 1.17 Impact Factor
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MRS, San Francisco, California, USA; 01/1998
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MRS, San Francisco, California, USA; 01/1998
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ABSTRACT: Plasma doping (PD) processes utilizing PH<sub>3</sub>/He and B<sub>2</sub>H<sub>4</sub>/He plasmas to fabricate CMOS devices are presented. The applications of PD in ultra-shallow junctions are discussed. Low contamination levels and good device characteristics were achieved
Electron Devices Meeting, 1997. Proceedings., 1997 IEEE Hong Kong; 09/1997
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ABSTRACT: Summary form only given. An empirical-analytic approach has been used for the plasma chemistry analysis of plasma ion implantation (PII) doping experiments. Least square (LS) fittings of SIMS profiles have been performed to find the relationship between gas, plasma, and dose compositions in multi-species plasmas and to optimize gas recipes and process conditions. A dynamic sheath model of the multi-species plasma has been used as a basic function for fitting. Good consistence between modeling and experiments for BF<sub>3</sub> and PH<sub>3</sub> PII doping processes was present. A PDP1 plasma simulation verified the results of the modeling
Plasma Science, 1997. IEEE Conference Record - Abstracts., 1997 IEEE International Conference on; 06/1997
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ABSTRACT: Summary form only given. The characteristics of the plasma sheath and ion energy during plasma immersion ion implantation (PIII) process are very important for the optimum configuration design and process control. A hydrodynamic model and a quasistatical model have been established to describe PIII process for dielectric substrates
Plasma Science, 1997. IEEE Conference Record - Abstracts., 1997 IEEE International Conference on; 06/1997
