Welcome to Lawrence J. Overzet's Web Pages

UNDER RECONSTRUCTION (slowly...)   Updated: 10/97

THE PLASMA APPLICATIONS LABORATORY (PAL)

Overview of Research:

Our research interests are primarily focused on the study of plasmas used in semiconductor processing. In particular, we have developed plasma diagnostics for semiconductor processing discharges and have extensive experience in determining plasma kinetics. We have also submitted patents for a high density plasma source, a plasma potential controller and a fast double Langmuir probe. We have sophisticated Langmuir probes, B-dot probes, microwave interferometers, an energy analyzing mass spectrometer and an ICCD camera with imaging spectrometer. We are always interested in industrially relevant projects and each graduate student routinely does a summer internship at a local company on a project related to plasma processing.
 

Present Research Grants and Contracts:

• National Science Foundation - NSF Young Investigator and  Ion-Ion plasmas, Fundamentals and Applications.
• State of Texas - Advanced Research Program on Pulsed High Density Plasmas.
• Beta Squared Inc. - Program on High Density Plasmas.
• Texas Instruments Inc. - IDEAS Program on the Growth of Gate Dielectrics.

Faculty:

 Dr. Lawrence J. Overzet

The founder of the Lab in 1989.  Dr. Overzet received his BSEE, MSEE and Ph.D. in Electrical Engineering from the University of Illinois at Urbana-Champaign in 1983, 1986 and 1988 respectively.  He became an Assistant Professor at the University of Texas at Dallas in late 1988. He received the National Science Foundation's Young Investigator award in 1992. In 1994, he became an Associate Professor with tenure, a position he currently holds. He is a member of the American Vacuum Society, and the IEEE.

A professor to be determined.

The Electrical Engineering (EE) Program at the University of Texas at Dallas (UTD) invites applications for a tenure-track faculty position at the Assistant or Associate Professor levels, beginning fall 1998, in fields related to semiconductor manufacturing and in particular, experimental/theoretical gaseous electronics. Responsibilities include the direction of doctoral students in research, and teaching at the undergraduate and graduate levels. Applicants must have a Ph.D. in EE (preferred), Chemical Engineering or Physics, must have demonstrated the ability to conduct research, should be willing to work as part of a research team, and should provide evidence of ability in teaching. Ph.D. candidates who expect to graduate in the Summer of 1998 may apply.

Students:

Marwan Khater, Ph.D.

Siva Kanakasabapathy, Ph.D.

Jennifer Kleber, Ph.D.

Raghavarao Denduluri, MSEE.

Richard Massetti, BSEE, MSEE.

Mark Rabalais, joining Spring 1998, MSEE, Ph.D.

 

• Three, 400 square foot, class 100,000 cleanroom laboratories spaces are available.
• Pass through access to a 5,000 square foot Class 1,000 clean room.
• Two Sun Workstations including a Sun SPARCstation 20 with dual 75 MHz SuperSPARC processors.
• Access to a Sun Ultra Enterprise 6000 multiprocessor batch server with EIGHTEEN 167 MHz UltraSPARC (V9) Processors with 512K cache each, 2.75 GBytes of RAM and 30 GBytes of disk space.
• The GEC reference reactor with either the inductively coupled or the capacitively coupled source.
• A modified Texas Instruments / Beta Squared PAC200 etcher for 6" wafers with high density plasma source.
• A pyrex tube plasma system for easy generation and diagnostics of plasmas at a large variety of pressures and and in a large variety of gas mixtures.
• Microwave interferometers at 8.6 GHz and 28.5 GHz with better than 0.3 microsecond time resolution.
• Mass spectrometer with 100 ns time resolution, better than 1 eV energy and 0.2 amu mass resolution.
• RF compensated Double Langmuir probe with better than 500 ns time resolution.
• RF compensated Single Langmuir probe with better than 0.015 ms time resolution, EEDF capability.
• ICCD camera with 5 ns time resolution, less than 0.5 nm wavelength and 0.2 mm spatial resolution.
• B-dot probes for magnetic field measurements.  (2.5 mm spatial resolution.)
• RF I-V probes for calibrated measurements of the rf power and impedance.
• Optical scanning monochromator.
• The School of Engineering has a machinist who is available for making small parts and modifications.  The machine shop consists of a lathe, mill, bandsaw, and other miscellaneous tools.  The machinist has access to a computer controlled mill on campus.
• The School of Engineering has a small electronics shop for maintaining equipment and labs. The electronics shop is always available for use.
• Secretarial services are presently provided by the School of Engineering.

     The University of Texas at Dallas has shown tremendous support for the Plasma Applications Laboratory.  Equipment worth more than $700,000 is available.  Discharges from DC to RF (0.3 - 35 MHz) to microwave (2.54 GHz) are all possible.  We can run parallel plate and inductively coupled RF plasma sources.  We currently use inductively coupled sources on our 4" glass system, and on the Gaseous Electronics Conference reference reactor.  Our plasma diagnostics include but are not limited to: three microwave interferometers at 8.6, 28.5 and 35 GHz, a time and energy resolved mass spectrometer for direct ion or neutral molecule detection, an optical scanning monochromator, a gated intensified CCD camera with an integrated imaging spectrometer, calibrated RF current and voltage probes, B-dot probes, time resolved single and double Langmuir probes, and the associated computer acquisition and control systems. We also have two Sun workstations and access to several high speed computers. For examples: we own a Sun SPARCstation 20 with dual 75 MHz SuperSPARC processors and we have access to a Sun Ultra Enterprise 6000 multiprocessor batch server. This last machine has 18-167 MHz UltraSPARC (V9) Processors with 512K cache each, 2.75 GBytes of RAM and 30 GBytes of disk space.
     The microwave interferometers (MWI) are designed for high sensitivity and speed.  Two have sub-microsecond time resolution and the 8.6 GHz MWI will measure electron densities as low as 10⁸ cm^-3 on the GEC reactor.  Both single Langmuir probe controllers allow time resolved measurements with a resolution of approximately 0.015 ms.  The double Langmuir probe now allows 500 ns time resolution.  This allows us to investigate discharges using both the microwave interferometer and the Langmuir probe.  The probe system can give us information on the spatially resolved electron and ion density, the plasma potential, floating potential, and electron temperature, while the microwave interferometer gives us information on the spatially averaged electron concentration and acts as a check for the Langmuir probe.  For example, the MWI will easily indicate when the Langmuir probe is beginning to perturb its surroundings.  This is generally not obvious from the Langmuir probe IV curve by itself.
     The RF-IV probes allow us to measure the effective RF impedance of the plasma and sheath.  These calibrated probes were designed for the Gaseous Electronics Conference reference reactor and have been used to measure the time resolved impedance of a few discharges in that cell.  They sample the RF current and voltage which is then sent to a computer program for calibration.  Our program allows us to measure the plasma impedance and RF power as a function of time with approximately a 150 ns time resolution.
     The Extrel Mass spectrometer has approximately a 220 amu upper limit and an energy resolution of approximately 1 eV.  The present electronics allow us to investigate from approximately 5 eV to approximately 100 eV.  Below 5 eV the energy analyzer transmission becomes small, and our present power supplies reach maximum values around 100 eV.  A pinhole aperture to the plasma allows direct plasma ion detection of either positive or negative ions, and neutrals can be detected by using the filaments.  The output signal can be time resolved with approximately a 100 ns minimum time resolution.
     A Princeton Instruments gated ICCD camera with integrated 1/3 meter imaging spectrometer allows us to measure the plasma light emissions with as small as 5 ns time resolution, less than 0.5 nm wavelength resolution and less than 0.2 mm spatial resolution.  Using it allows us to measure the light intensity emanating from the discharge with wavelength resolution, spatial resolution, and temporal resolution all simultaneously.  This instrument will allow us to investigate the chemistry of a variety discharges through light emission, induced fluorescence and absorption.
     We have pass through access to a 5,000 square foot Class 1,000 clean room containing semiconductor processing equipment including optical and e-beam lithography, chemical processing facilities, vacuum evaporators and sputtering systems. In addition, a Phillips SEM, a high resolution AFM and scanning tunneling microscopy are available.

 

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