This paper identifies the defect adders, for example, post  hard-mask etch residue, post metal etch residue, and blocked etch metal island and investigates the removal characteristics of these defects within the oxide-masked Al etching process sequence. Post hard-mask etch residue containing C atom is related to the hardening of photoresist after the conventional post-RIE ashing at <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msup><mml:mn>275</mml:mn><mml:mo>&#x2218;</mml:mo></mml:msup><mml:mtext>C</mml:mtext></mml:math>. An in situ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mtext>O</mml:mtext><mml:mn>2</mml:mn></mml:msub></mml:math>-based plasma ashing on RIE etcher was developed to prevent the photoresist hardening from the high-ashing temperature; followed wet stripping could successfully eliminate such hardened polymeric residue. Post metal etch residue was caused from the attack of the Al sidewall by Cl atoms, and too much <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mtext>CHF</mml:mtext><mml:mn>3</mml:mn></mml:msub></mml:math> addition in the Al main etch step passivated the surface of Al resulting in poor capability to remove the Al-containing residue. The lower addition of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mtext>CHF</mml:mtext><mml:mn>3</mml:mn></mml:msub></mml:math> in the Al main etch step would benefit  from the residue removal. One possibility of blocked etch metal island creating was due to the micromasking formed on the opening of TiN during the hard-mask patterning. We report that an additional TiN surface pretreatment with the Ar/<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mtext>CHF</mml:mtext><mml:mn>3</mml:mn></mml:msub></mml:math>/<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mtext>N</mml:mtext><mml:mn>2</mml:mn></mml:msub></mml:math> plasmas could reduce the impact of the micromasking residues on blocked metal 
etch.

Hong-Ji Lee

Che-Lun Hung

Chia-Hao Leng

Nan-Tzu Lian

Ling-Wu Young

Tahone Yang

Kuang-Chao Chen

Chih-Yuan Lu

Etch Defect Characterization and Reduction in Hard-Mask-Based Al Interconnect Etching

Miniature ion thrusters are well suited for future space missions that 
                  require high efficiency, precision thrust, and low contamination in the mN to 
                  sub-mN range. JPL&#39;s miniature xenon Ion (MiXI) thruster has demonstrated an 
                  efficient discharge and ion extraction grid assembly using filament cathodes 
                  and the internal conduction (IC) cathode. JPL is currently preparing to incorporate a miniature 
                  hollow cathode for the MiXI discharge. Computational analyses anticipate that an axially 
                  upstream hollow cathode location provides the most favorable performance and beam 
                  profile; however, the hot surfaces of the hollow cathode must be sufficiently downstream 
                  to avoid demagnetization of the cathode magnet at the back of the chamber, which can 
                  significantly reduce discharge performance. MiXI&#39;s ion extraction grids are 
                  designed to provide <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mo>&#x003E;</mml:mo></mml:math>3&#x2009;mN of thrust; however, previous to this effort, the low-thrust 
                  characteristics had not been investigated. Experimental results obtained with the 
                  MiXI-II thruster (a near replica or the original MiXI thruster) show that sparse average 
                  discharge plasma densities of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mo>&#x223C;</mml:mo><mml:mn>5</mml:mn><mml:mo>&#x00D7;</mml:mo><mml:msup><mml:mrow><mml:mn>10</mml:mn></mml:mrow><mml:mrow><mml:mn>15</mml:mn></mml:mrow></mml:msup></mml:mrow><mml:mtext>&#8211;</mml:mtext><mml:mrow><mml:mn>5</mml:mn><mml:mo>&#x00D7;</mml:mo><mml:msup><mml:mrow><mml:mn>10</mml:mn></mml:mrow><mml:mrow><mml:mn>16</mml:mn></mml:mrow></mml:msup></mml:mrow></mml:math><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mtext>&#x2009;</mml:mtext><mml:msup><mml:mtext>m</mml:mtext><mml:mrow><mml:mo>-</mml:mo><mml:mn>3</mml:mn></mml:mrow></mml:msup></mml:mrow></mml:math> allow the use of very low 
  beamlet focusing extraction voltages of only <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mo>&#x223C;</mml:mo><mml:mn>250</mml:mn></mml:math>&#8211;500&#x2009;V, thus providing thrust levels 
  as low as 0.03&#x2009;mN for focused beamlet conditions. Consequently, the thrust range 
  thus far demonstrated by MiXI in this and other tests is 0.03&#8211;1.54&#x2009;mN.

Richard Wirz

Regina Sullivan

JoHanna Przybylowski

Mike Silva

Hollow Cathode and Low-Thrust Extraction Grid Analysis for a 
                        Miniature Ion Thruster

An impulse power supply has been designed, simulated, and tested in order to feed the primary of a high-frequency transformer. Pulse power system has been widely used for plasma applications. The operational principle of the pulse power system is that the energy from the input source is stored in the capacitor bank device through a dc-dc converter. Then, when a discharging signal is given, the stored energy is released to the load. The new family of ZCS converters is suitable for high-power applications using insulated gate bipolar transistors (IGBTs).  The power converter can achieve zero switching with the aid of high-frequency transformer. The device is capable of charging a 0.1&#x2009;<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mi>&#x03BC;</mml:mi></mml:math>F capacitor up to 5&#x2009;kV which accounts for a charging power of 5&#x2009;kJ/s. The novel control algorithm is achieved which eminently considers the nonlinear control characteristics of impulse power supply. The required charging voltage, together with the constraint on the charging time, translates into a required maximum power of 10&#x2009;kW reduced in this initial version to 5&#x2009;kW. The difficulty to reliably control such a power at the high-voltage side practically forbids any approach featuring a more or less stabilized DC high-voltage to be generated from a conventional 50&#x2009;Hz transformer through rectification.

R. B. Jadeja

S. A. Kanitkar

Anurag Shyam

FFT Analysis of a Series Loaded Resonant Converter-Based Power Supply for Pulsed Power Applications

Using a static mass spectrometer, we study the characteristics of multicharge plasma ions generated from solid targets under the action of a 
    15 nanosecond Nd:YAG laser radiation with maximal intensity <mml:math id="E1" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msup><mml:mrow><mml:mn>10</mml:mn></mml:mrow><mml:mrow><mml:mn>11</mml:mn></mml:mrow></mml:msup></mml:mrow></mml:math>&#x2009;<mml:math id="E2" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msup><mml:mrow><mml:mtext>W/cm</mml:mtext></mml:mrow><mml:mn>2</mml:mn></mml:msup></mml:mrow></mml:math>. We consider two-element solid targets with a mass of the heavy component ranging from 44.9 (Sc) to 174.9 (Lu) with main attention to the properties of oxygen ions. The time-of-flight measurements show that oxygen ions are obtained in the range of the energy 
    <mml:math id="E3" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mi>E</mml:mi></mml:math>  =  40&#x2013;250&#x2009;eV with maximal charge <mml:math id="E4" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msub><mml:mi>Z</mml:mi><mml:mrow><mml:mtext>max</mml:mtext></mml:mrow></mml:msub><mml:mo>=</mml:mo><mml:mn>2</mml:mn></mml:mrow></mml:math>. The latter is independent on the target composition for the given intensity of the laser radiation. However, the properties of the energy spectra of oxygen ions strongly depend on the second component of the target, which is explained by the interaction between the light and heavy elements of the target.

R. T. Khaydarov

U. S. Kunishev

Mass-Charge and Energy Spectra of Oxygen Ions in a Two-Element Laser-Produced Plasma

The aim of our study is to generate microstructures in order to improve optical properties of monocrystalline
silicon. By mean of fluorocarbon plasma barrel texturing and under certain process conditions, silicon turned black.
As a result of silicon surface-plasma particles reactions, porous microstructures are formed, while a longer  process time microspikes are developed. These microstructures are responsible of the high level of light trapping on almost the whole range of the usable portion of the solar spectrum. In the wavelength range of 400&#x2013;1100&#x2009;nm, the AM1.5G weighted reflection has been reduced to 6.20&#37;. In addition to good trapping, this surface morphology leads to superior absorption, which is about 95&#37; in the 600&#x2013;1000&#x2009;nm range and decreases to 36&#37; at 1200&#x2009;nm. This material is thus less transparent and absorbs near infrared light far more than the untreated silicon. Secondary ion mass spectrometry shows that elements from the ambient gas are deposited or superficially introduced   into the silicon. In addition to surface texturing, these impurities are probably the reason of absorptance enhancement. Moreover, a pore formation mechanism is proposed.

A.  El amrani

R.  Tadjine

F. Y. Moussa

Microstructures Formation by Fluorocarbon Barrel Plasma Etching

A Penning discharge tube has been used as the excitation source for optical
detection of gaseous species concentrations in a neutral gas. This type of diagnostic
has been primarily used in magnetic fusion energy experiments for the detection of minority
species in the effluent gas (e.g., for helium detection in a deuterium background).
Recent innovations (US Patent
no. 6351131, granted February 26, 2002) have allowed for extension of the operation range from <mml:math id="E1" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mo>&#x003C;</mml:mo></mml:mrow></mml:math>1 Pa to as high as 100 Pa and possibly beyond. This is done by dynamically varying the gauge magnetic
field and voltage to keep the optical signals nearly constant (or at least away from a nonlinear
dependence on the pressure). However, there are limitations to this approach, because the
Penning discharge can manifest itself in a number of modes, each exhibiting a different spatial
emission pattern. As a result, varying the discharge parameters can cause the gauge to
undergo transitions between these modes, disrupting any intended monotonic dependence
of the overall emission on the varied parameter and hence any predicable impact on the emission.
This paper discusses some of the modes observed experimentally using video imaging of
the discharge. It also presents a first successful application, a particle-in-cell (PIC) code, to
simulate these modes and a mode transition. The hope is that a good understanding of the
physics involved in the mode transitions may allow for methods of either avoiding or
suppressing such transitions. This would aid in broadening the use of this plasma-based sensor technology.

C. C. Klepper

R. C. Hazelton

F. Barakat

M. D. Keitz

J. P. Verboncoeur

Observation and Modeling of Optical Emission Patterns and Their Transitions in a Penning Discharge

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International Journal of Plasma Science and Engineering - Table of contents 2008

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