Monthly Newsletter -- May 2007

This is the monthly newsletter for the month of May. May 21-25 is the SID meeting in Long Beach. As I mentioned in last month’s newsletter, please be sure to let us know if you would like one of us to check out a talk or booth that may have information that you are interested in.

Next month is the Gordon Conference on Liquid Crystals which focuses on the latest advances in the field. If there are any particular topics that you are interested in getting the latest information on, I will be glad to try to help with this. Please just let us know.

CLEANROOM NEWS

Process Spotlight: UV/Ozone Cleaning
Proper glass cleaning is critical to any success when fabricating liquid crystal displays. Particle contamination is the most obvious issue, as it can cause electrical shorts, cell gap variations, and coating defects. But just as important is the wettability of the surface, which controls adhesion of photoresist layers and alignment layers. Organic film contamination, often residues from previous process steps, can cause alignment layer de-wetting, and overetching of ITO during photolithography.

UV/Ozone cleaning is a straightforward way to control this organic film contamination. It can be used as a final cleaning step, after ultrasonic or megasonic cleaning for particle removal. It is similar in nature to oxygen plasma cleaning, and can be used to remove coatings in some instances, though it is usually slow-acting.

The concept behind UV/ozone cleaning is straightforward—low pressure mercury lamps are used to generate short wavelength UV radiation (UV lamps for photolithography are typically high pressure lamps, to generate longer wavelength UV light). 185 nm radiation is absorbed by O2 molecules which recombine to form O3, or ozone. 254 nm radiation is absorbed by surface organic films, forming an energized, more reactive state, and is also absorbed by O3, which breaks down to form radical oxygen, a single, highly reactive oxygen atom. The radical oxygen then reacts with any surface organic films, with CO2 and water vapor the primary byproducts. These byproducts are exhausted from the chamber, leaving a very clean, hydrophilic surface.

Surface wettability can be quantified by making surface contact angle measurements (to be described in a future process spotlight).

UV/Ozone cleaning systems are affordable, and a good choice as a final cleaning step before spincoating or offset printing. The LCI has two systems, a UVOCS UV/O3 cleaner and a Samco UV/Ozone cleaner. The UVOCS system is a low cost R&D type, while the Samco unit has an ozone generator to create much higher concentrations of ozone and a hotplate to enhance cleaning. Both systems fit up to 14” glass substrates. Because short wavelength UV is absorbed by air, distances from lamp to substrate surface must be short, so glass is usually placed on a flat surface underneath a series of mercury lamps. Because of this, glass is processed individually, not in large carriers—higher throughput can be achieved with multiple systems.

For more information on UV/ozone cleaning and equipment, see:

http://uvocs.com/
http://jelight.com/ultraviolet-products.php
http://www.crystec.com/senteche.htm

If you are interested in learning more about our capabilities, or reserving time in the facility, please contact Doug Bryant.

EQUIPMENT UPDATE
Several tools in the LCDRF will be undergoing maintenance and upgrades, or have recently completed maintenance:

A new research tool for Dr. Qihuo Wei’s group, an Oxford 80+ reactive ion etcher (RIE) system, is being installed this month, and will require movement of one of the Blue M ovens. Shuffling of equipment will begin on May 11, with manufacturer installation tentatively scheduled for late May.

The GenVac SC1 Coater is currently down. Ion gun repairs are in process with assistance from GenVac Aerospace, and it is expected that the ion gun will be restored to full functionality by late May. The system will require testing at that point to re-qualify the ITO deposition process. Deposition of materials not requiring the ion beam, such as aluminum, gold, chromium, aluminum oxide, and nickel, are currently available.

The Technics PlanarEtch II plasma etcher is currently down. Staff did not spend time on this machine last month as planned, but hope to do so this month.

CLEANROOM AVAILABILITY DURING SID WEEK May 21-25, 2007
Doug will be attending the SID Conference the week of May 21; as in previous years, the cleanroom will be available during that week by prior arrangement only. Please contact Doug as soon as possible if you require facility access during that time. The room will be open, but little or no support will be available.

UNIVERSITY STEAM SHUTDOWN WEEK OF MAY 14-18 AND CLEANROOM IMPACT
The university has its annual maintenance shutdown of steam generation, which will interrupt hot water to university buildings, as well as air conditioning systems. This may cause cleanroom temperature and humidity to fall out of spec if outdoor conditions are extreme (as they usually are during shutdown week!). This might affect spincoating as well as cell assembly conditions.

IPP INFORMATION RESOURCE NEWS REPORT
Last month we mentioned our ACF bonding capability here at LCI. This month, we would like to point out our machining capabilities.

LCI has its own machine shop on the premises. Many research projects call for some type of part to be made to hold a cell to a machine, to make a fixture for a device, or even to make a special device. We do not have any full time machinists, nor do we do machining strictly as work for hire, but we do have staff that are capable of using the machine shop to support in-house projects with the making of necessary parts or to modify tooling for in-house equipment. We have cutting, milling and lathing capabilities. We can drill and tap holes. We can generate AutoCAD drawings for desired parts, or we can work off rough sketches. If you have need for any special machining for any of your LCI-related projects, please let us help you define the project and draft up a quote for a statement of work to see if we can help.

The complete manual for the EOM software has been reported to be a bit cumbersome for first time users. So, we have created a 'Quick Start' manual for users wishing to use the software for the first time and who may have limited knowledge of how parameters work.

The Quick Start manual assumes that the software is installed and that a user is using a system of the most commonly found hardware configuration. For other configurations or for software installation directions, the full manual should be consulted. The first file of this type is being placed on the web site and is titled "Quick Start: EOM - Contrast Ratio, Normal Incidence."

EOM Quick Start Manual: Contrast Ratio Measurement, Normal Incidence
This document is intended as a quick start manual for doing Contrast Ratio at normal angle of incidence. It will describe the most common hardware configuration and the most common parameter settings chosen by most users. If you require assistance for other hardware configurations or additional parameter selections, please review the full EOM Manual that comes with the EOM software installation.

Required Hardware:
1. Computer with EOM Software and Internal OceanOptics Card (USB Spectrometer)
2. National Instruments External Board Model BNC-2090
3. Power Source for Light Source is Oriel Fiber Optic Illuminator MN 77501
4. Oriel Light Source
5. Signal Amplifier (if more than 10 V output required)
6. Coaxial cables (1 short jumper, 1 long input, 1 long output with split out leads for sample)
7. All related data and power cables.

Your hardware setup should be as follows:
1. EOM software is installed on PC
2. OceanOptics card is installed in PC and drivers loaded
3. Big data cable goes from PC card to National Instruments external signal board (data cable port on external board is switched to MIO-16)
4. National Instruments external board has ACH0 connected by coaxial cable to detector output (Coaxial input ACH0 is switched to SE)
5. National Instruments external board has DAC0OUT connected to a split coaxial for attaching leads to samples
6. National Instruments external board has DAC1OUT and PF10/TRIG1 jumpered with short coaxial cable
7. Power source for lamp is plugged into lamp and gets AC power from the wall
8. Oriel lamp gets power from the power source
9. IR filter is installed in front of light source
10. Attenuators (Neutral Density Filters) need to be used (if necessary) to knock down detector voltage to less than 10 volts
11. Detector has AC power to wall plugged in

The Optical Board should be set up as follows:
1. Light Source
2. IR filter
3. Neutral Density Filter(s) (if required)
4. Polarizer (if sample does not have them attached)
5. Sample Holder connected to drive leads from DAC0OUT
6. Polarizer (if sample does not have them attached)
7. Detector

Turning on Hardware:
1. Turn on computer.
2. Turn on power for light source (lamp needs 30 minutes to stabilize)
3. Attach leads from DAC0OUT to sample
4. Attach sample to Sample Holder
5. Open up EOM software

Making the Contrast Ratio Measurement:
NOTE: This procedure is for Contrast Ratio measurement at normal incidence (no stepper motor needed):

1. Select Static Response from main software menu
2. Click on the button, Configure Waveform Driver

a. Click on the button, Load Waveform
b. Select ‘asquare.wfm’ from the list
c. Click on the button, Load
d. In the parameter area Drive Mode, select Fixed Number
e. In the parameter area Waveform reps/sec, type in the frequency of measurement you want (about 1 kHz is default)
f. In the parameter area State 1, type in the drive voltage you want for one of the two LCD states (fully ON or fully OFF)
g. Click on the button, Turn Waveform On
h. Click on the button, Quit

3. Click on the button, Configure Detector Driver

a. Click on the button, Load Detector
b. Select ‘Chan0_Rse_unipolar.det’ from the list
c. Click on the button, Load
d. In the parameter area Acquisition Parameters, under the section, Data Mode, select ‘continuous’
e. Click on the red button that says “Detector OFF” (it will turn green and change to “Detector ON” and detector energies will be seen in real time. Make sure the value is under 10. If not, use Neutral Density Filters to drop the energy down under 10 for the state that passes the highest amount of energy.

4. With sample in place, set the voltage in section 2. above to one of the drive state voltages and record the output intensity in section 3. above. Then switch the voltage in section 2 to the other drive state’s voltage, and record the output intensity of that voltage state in section 3.
5. Take the output intensity of the bright state (high intensity state) and divide by the output intensity of the dark state (low intensity state) and this is the contrast ratio at normal incidence.

NEWS
SID International Awards go to Doane and Yang
The Society for Information Display has awarded Professor J. William Doane with the 2007 Slottow-Owaki Prize and Professor Deng-Ke Yang with a Fellow Award. Information Display Magazine states that Doane will be recognized "for his outstanding contributions to education in the field of information display as the Director of the Kent State Liquid Crystal Institute and as the major professor for numerous graduate students in the field of liquid crystal technology." Yang is recognized "for his significant scientific and technological contributions to bistable reflective cholesteric displays and to polymer-stabilized cholesteric devices, and for his outstanding contributions to education in the field of liquid crystal technology." Page 42 of the April 2007 issue of the magazine has the complete list of award winners.

Kent State Announces New License Agreement to Kent Optronics
Technology invented jointly by Kent State University professor Dr. Deng-Ke Yang and Kent Optronics has led to a new licensing agreement for the university. The invention, a single layer multi-state ultra-fast cholesteric liquid crystal device, will be used primarily in relation to light shutters, enabling the creation of such devices as reflectors, light blockers, window glazing for energy conservation and other products.
For more information go to http://www.techtrans.kent.edu/pr/KOILicensePressReleaseNov06.pdf

CPIP Professors receive Research Collection Award Fund
On May 3, CPIP professors Antal Jakli, Oleg Lavrentovich, Peter Palffy-Muhoray and L.-C. Chien were awarded $5,000 to support the purchase of books about liquid crystals which are not currently available through the Kent State Libraries collections.

IPP Members, please note: Kent State University has a wide assortment of literature resources available, so please let us know if you have any information needs.

LCI Seminars
On May 2: Prof. Timothy Sluckin, Faculty of Mathematical Studies, University of Southampton, United Kingdom presented “Theories of Biaxial Liquid Crystals”.

Ohio Nanotechnology Summit 2007
On April 24-25, the LCI took part in (and sponsored) the 2007 Ohio Nanotechnology Summit in Akron. The summit's main focus was on nano materials, nano processing, nano bio and nano photonics and electronics. Kent State's John West and Satyen Kumar and Kent Display's Asad Khan gave presentations.

CPIP Student Awarded University Fellowship
CPIP Student John Harden has been awarded a University Fellowship for the academic year 2007-2008. Harden, advised by Professor Antal Jakli, is a fourth year CPIP student working towards a Ph.D.

LCI Conference Presentations

• At the Society for Information Display conference in Long Beach, Phil Bos will provide a tutorial on the off-axis viewing characteristics of LCD display modes. Also students in his lab will make several presentations: Yong-Kyu Jang will provide an oral talk of the universality of the white state viewing angle, and a poster related to the effect of multiple reflections on the contrast ratio of LCDs; Mike Dorjgotov will provide an oral presentation on the use of etalons in the design of a high efficiency projection display mode; and Mitya Reznikov will present results on the effect of the alignment layer in providing analog smectic C* devices.
• CPIP Professor Peter Palffy-Muhoray presented "Nanoparticle liquid crystals as negative index materials," on April 16-20, 2007 at SPIE Optics and Optoelectronics Europe, Prague, Czech Republic.

LCI Welcomes Miller as New Grants Assistant
After 7 years of service at LCI, Marybeth Lipinski recently left to begin a teaching career in Akron. We wish her well! This week the LCI welcomes Dawn Miller who will take over the Grants Assistant position. Miller worked in the Physics Department as a Grants Assistant about 10 years ago and has experience in grants and purchasing procedures as well as experience working in a science department.

June 19-28 NSF Ferroelectric Workshop at KSU
The June 19-28 NSF-sponsored “Ferroelectric Phenomena in Liquid Crystals” workshop objectives comprise both education and research. The goal of the educational component is to expose graduate students (from both the mathematical and the physical sciences) to several aspects of liquid crystals related to the three topics above, from the points of view of both physics and mathematics. The main research objective is to foster a lively exchange between the participating physicists and mathematicians on the concerned topics. The main topics include: Fluid fibers (banana, lyotropic); liquid crystal elastomers; defects and their visualization, with emphasis on ferroelectric materials. For more information visit: http://ferro-workshop.lci.kent.edu .

Be sure to let us know if you would like more detailed information about any activities at the LCI.
Phil Bos
pbos@lci.kent.edu
330-672-2511