Two-Terminal Devices Technologies for AMLCDs
TFT-LCD Gate and Data Bus-Line Design and Process Technologies
High-Aperture and Fault-Tolerant Pixel Structure for TFT-LCDs
Cell Design Considerations for High-Aperture-Ratio Direct-View and Projection Polysilicon TFT-LCDs
A High-Density 1280x1024 Transferred-Silicon AMLCD
A 1.8-in. Poly-Si TFT-LCD for HDTV Projectors with a 5-V Fully Integrated Driver
A Color AMLCD with Fully Integrated Drivers Using a Low-Temperature CdSe TFT Process
Circuit Design for a-Si AMLCDs with Integrated Drivers
Future Prospects of Large-Area Direct-View LCDs
Novel Key Technologies Used to Fabricate Very-Large-Area TFT-LCD Panels
16.1-in. TFT-LCD for Engineering Workstations
A 13.8-in.-diagonal 1-Mpixel TFT-LCD with Light-Shielded Fully Self-Aligned TFTs
Multi-Field Driving Method for Reducing LCD Power Consumption
A Compensation Driving Method for Reducing Crosstalk in XGA and Higher-Resolution TFT-LCDs
A 6-bit Digital Data Driver for Color TFT-LCDs
A High-Speed 6-bit TFT-LCD Driver for COG Applications
New Single-Crystal-Silicon AMLCD Technology
Low-Temperature Polysilicon Transistors for Projection AMLCDs
a-Si AMLCD PDLC Light Valve with 30% Optical Transmittance
A 23-cm-Diagonal Bright Reflective Guest-Host TFT-LCD
Electrical Properties of Double LDD Poly-Si TFTs with Defect-Tolerant Redundancy for AMLCDs
Bias-Temperature Instability in Hydrogenated Poly-Si TFTs
A Gray-Scale Drive Method for TFT-LCDs with Binary-Value-Output Drivers
A Transmission-Line Approach for Line-Continuity Testing of Active-Matrix Arrays
AMLCD with Integrated Drivers Made with Amorphous-Silicon TFTs
Two-Terminal Devices
Technologies for AMLCDs
R. A. Hartman
Flat Panel
Display Co. Eindhoven, The Netherlands full
paper
Two-Terminal Devices have been studied as switching elements for Active Matrix Liquid Crystal Displays (AMLCD) since the early seventies. Diodes and other two-terminal devices offer the potential advantage of a simple fabrication process: thin layers, few layers, few masks and no crossing conductors on a single plate, while in performance displays can be manufactured with a quality that is at least as good as the more common three terminal Thin-Film-Transistor (TFT) approach. Several types of displays with TFD devices, a-Si p-i-n, a-SiNx and Ta2O5 Metal-Insulator-Metal (MIM) devices, are compared with each other and the display performance of a-Si TFT Displays. Essential for good operation is the drive scheme. A superior system is the five level drive with reset. Display sizes range from viewfinders with a diagonal under 1" to data graphic displays of 14" and have been developed to operate in extreme environments like professional projection systems and in cars.
TFT-LCD Gate and
Data Bus-Line Design and Process Technologies
M. Ikeda
Toshiba R&D Center, Yokohama, Japan full paper
Gate and data bus lines not only require low resistivity but also process simplicity. Bus-line technologies based on the metal characteristics, array design, process, TFT structure, and cost will be discussed. A specific example of Mo-W alloy for XGA panels will be described.
High-Aperture
and Fault-Tolerant Pixel Structure for TFT-LCDs
S. S.
Kim, S. H. Moon, D. G. Kim, N. D. Kim
Samsung Electronics,
Kyungki-do, Korea full paper
An optimized fault-tolerant cell structure for color TFT-LCDs with high aperture ratio has been successfully developed. The new cell is composed of a ring shape storage capacitor electrode and a "dual gate" bus-line, which features a primary light shield around pixel ITO with more cell assembly accuracy and a "fault-tolerant" TFT-array fabrication. By employing the new cell structure, aperture ratios of 70% and 65% were realized in 10.4-inch-diagonal color VGA and SVGA, respectively. With this high aperture ratio and a new driving technology, a total power consumption of 2W has been achieved in 10.4-inch-diagonal color SVGA (800x600 pixels) module.
Cell Design Considerations for
High-Aperture-Ratio Direct-View and Projection Polysilicon TFT-LCDs
I-W. Wu
Xerox PARC, Palo Alto, CA full
paper
Polycrystalline silicon (p-Si) TFTs have several important advantages over a-Si TFTs as pixel switching elements for high density AM-LCDs, as well as allowing the integration of peripheral driver circuits on the same substrate. Critical issues affecting the performance of p-Si TFT AMLCD pixels are analyzed, including: lithographic resolution and overlay format, storage to LC capacitance ratio, and gate dielectric thickness. Tight design rules can be applied to build high density projection display panels with adequate aperture ratios using wafer lithographic tools. For example, a 10x10 sq µm pixel with 36% aperture can be fabricated using a 1µm design rule. Low temperature p-Si TFTs on glass substrates are more suitable to fabricate large size direct-view panels for the next generation high resolution displays.
A
High-Density 1280x1024 Transferred-Silicon AMLCD
F.
Cuomo, J. Atherton, A. Ipri, D. Jose, R. Stewart, G. Taylor
David
Sarnoff Research Center, Princeton, NJ
M. Batty, M. Spitzer, D. P.
Vu
Kopin Corp., Taunton, MA
B. Ellis, H. Franklin
Honeywell,
Inc., Phoenix, AZ
B. Rhoades, M. Tilton
Standish
Industries, Lake Mills, WI
B.-Y. Tsaur
MIT Lincoln
Laboratory, Lexington, MA full paper
A fully scanned 1280x1024 display with a density of over 1000 pixels per inch was fabricated using xSi technology. This display uses five volt, six bit per pixel input data with D/A conversion performed on chip. These fully integrated scanners reduce lead count to 66 input and 6 test leads.
A 1.8-in. Poly-Si
TFT-LCD for HDTV Projectors with a 5-V Fully Integrated Driver
S. Higashi, Y. Matsueda, S. Takenaka, M. Miyasaka, I. Yudasaka, H.
Ohshima
Seiko-Epson Corp., Suwa, Japan
full paper
A 1.8-in. poly-Si TFT-LCD for an HDTV projector (1440 x 1024) with 5-V fully integrated drivers and an aperature ratio of 47.5% has been developed, By improving the electric characteristics of the TFTs , the shift register can be driven up to 10 MHz of clock frequency with 5 V of applied voltage. A new configuration of TFTs for level shifting circuits was used to drive the liquid crystal with higher voltage. The specifications of the developed drivers and the TFT-LCD are shown.
A Color AMLCD with Fully
Integrated Drivers Using a Low-Temperature CdSe TFT Process
K. Schleupen, P. Aymar, J. Glueck, E. Lueder, T.
Kallfass, M. Dobler
University of Stuttgart, Stuttgat, Germany full paper
A projection-system with a fully integrated 1.9-in.-diagonal color TV-AMLCD with 288(v)x480(h) pels was built. The self scanned display is fabricated using a low-temperature CdSe-TFT process (< 400°C) enabling the use of cheap AF45 glass substrates. The high performance of the TFTs has been proven by fabricating shift registers for video drivers with only seven TFTs per stage working up to 7.5MHz even for a channel length of 30µm for all TFTs. The integrated thin-film circuits also contain 4-bit switched capacitor D/A-converters for each column.
Circuit Design for a-Si AMLCDs with Integrated Drivers
R.
G. Stewart, J. Dresner, S. Weisbrod, R. I. Huq, D. Plus
David
Sarnoff Research Center, Princeton, NJ
B. Mourey, B. Hepp
Thomson-LCD,
Moirans, France
A. Dupont
Thompson ER&D, Strasbourg, France full paper
The feasibility of integrated drivers for AMLCDs based on amorphous-silicon TFTs has been investigated, taking into account the low mobility, high threshold voltage, and high parasitic capacitance, as well as having only n-type enhancement devices. The feasibility was simulated using clever designs for the column and row drivers, as well as multiple inputs to reduce the data rate. The basic operation and fundamentals of the design of the two drivers, as well as the demultiplexing scheme, are reviewed.
Future Prospects of Large-Area
Direct-View LCDs
M. Hijikigawa, H. Take
Sharp Corp.,
Nara, Japan full paper
The key technologies and performance factors required to realize large-area direct-view TFT-LCDs are discussed. A 21-in. -diagonal full-color TFT-LCD is used as an example.
Novel
Key Technologies Used to Fabricate Very-Large-Area TFT-LCD Panels
E. Kaneko
Hitachi Research Laboratory, Hitachi-shi, Japan full paper
Several novel key technologies necessary to fabricate very large area TFT-LCD panels are described. The results of a printed-mask TFT circuit pattern fabrication technique is reported. Results for a SiO2 layer, fabricated by using TEOS gas, and other findings are also summarized.
16.1-in. TFT-LCD for Engineering Workstations
S. Hirano
IBM Japan Ltd., Yamato Laboratory, Kanagawa, Japan full paper
A 16.1" TFT/LCD with 1280x1024 resolution has been developed for EWS use as an alternative to a 19" CRT monitor, aiming at space- and power- savings.
Major specifications are;
Pixel court 1280x1024
Pixel pitch 249µm
Grey
level 6 bit
Brightness >or= 100 nit
Contrast ratio >or= 1:100
Total power consumption
< 50W
The most important factor of large EWS screen design is total "Front of Screen Quality" for the application. First total design are discussed and then major elements of display namely TFT array, liquid crystal cell, color filter, drive circuit and back light system are described.
A
13.8-in.-diagonal 1-Mpixel TFT-LCD with Light-Shielded Fully
Self-Aligned TFTs
M. Akiyama, T. Kiyota, Y. Ikeda, T.
Koizumi, M. Ikeda, K. Suzuki
Toshiba R&D Center, Yokohama, Japan full paper
A fully self-aligned amorphous silicon TFT employing a black-matrix(BM)-on-array configuration to reduce TFT photo-current was developed. A 13.8-in.-diagonal TFT-LCD with 1152 x 900 pixels has been successfully fabricated using the new structure with channel length of 6 µm and confirmed not to generate photo-induced cross-talk up to 50,000 lx of back-light illuminance.
Multi-Field Driving Method for Reducing LCD Power Consumption
H. Okumura, G. Itoh
Toshiba R& D Center, Yokohoma, Japan full paper
A multi-field driving method was developed in which a displayed image was divided into over three interlaced sub-field images and visible flicker did not occur even if the image refresh rate was decreased. This method made it possible to reduce a power consumption of a TFT-LCD driving circuit by more than half, compared to that with conventional methods.
A Compensation Driving Method for Reducing Crosstalk in XGA and
Higher-Resolution TFT-LCDs
F. R. Libsch, A. Lien
IBM
T. J. Watson Research Center, Yorktown Heights, NY
full paper
A new driving scheme to compensate for cross-talk in TFT-LCDs that is image pattern independent with no background variation is presented and compared to existing commercially used cross-talk compensative driving schemes. In addition, a testing methodology and a capacitive coupling model have been developed to investigate crosstalk in XGA and higher-resolution TFT-LCDs and to optimize an appropriate compensative driving design. Crosstalk examples and results correlating various types of crosstalk phenomena, display driving schemes, and pixel layouts with corrective action measures will be presented.
A 6-bit Digital
Data Driver for Color TFT-LCDs
S. Saito, K. Kitamura
NEC Corp., Kanagawa, Japan full paper
A 6-bit digital data driver with 240 outputs for color TFT-LCDs has been developed by implementing a new 64-gray-scale-level generation scheme. The scheme is comprised of a reference voltage generator, ROM decoders, and low power operational amplifiers of wide dynamic range, and can realize small die size, low power consumption, and high-speed operation. Using these drivers, with their high-speed capability, an SVGA display can be assembled with tape carrier packages on only one side of the glass.
A High-Speed 6-bit TFT-LCD
Driver for COG Applications
K. Meinstein, C. Ludden, M.
Hagge, S. Carruth
Crystal Semiconductor Corp., Austin, TX full paper
A 258 output 6-bit driver has been developed for COG applications. It has a 64µm output pitch and is capable of high speed operation with a 3.3V digital interface. Because of an efficient architecture and compact layout combined with a 0.6µm CMOS process technology, the die size of this driver is only 22.7 sq mm. The power consumption of this driver is very low due to a weighted resistor string scheme used in the DAC, and it has the additional features of optional clock doubling and internal data inversion which make it an extremely versatile driver.
New
Single-Crystal-Silicon AMLCD Technology
J.-B. Yoon,
H.-J. Lee, C.-J. Han, C.-K. Kim
KAIST, Taejon, Korea full paper
An AMLCD was fabricated on a crystalline silicon (xSi) substrate of AMLCD to achieve full integration and high resolution using a conventional bulk MOSFET fabrication process. High light transmission is achieved by the vertical etching of Si in the light path with anisotropic etchant of KOH. The devices exhibit an electron mobility and subthreshold slope of 600 sq cm/Vs and 65mV/decade, respectively and a pixel size of 50µm x 70µm was obtained.
Low-Temperature
Polysilicon Transistors for Projection AMLCDs
J. Jang,
H. J. Lim, B. Y. Ryu
Kyung Hee University, Seoul, Korea full paper
Undoped poly-Si film was deposited on glass by a remote plasma chemical vapor deposition at low substrate temperature using a mixture gas of SiF4, SiH4, He, and H2. Low resistive Ni-polycide layer can be formed by annealing Ni on ion-doped poly-Si. The poly-Si TFTs, made of as deposited poly-Si and Ni-salicide (self-aligned policide) layer at the maximum process temperature of 280°C, exhibited a field effect mobility of 10 sq cm/Vs, a threshold voltage of 5 V, a leakage current of 5.2E-12 A/µm at Vd=4V, and a gate voltage swing of 1.48 V/dec. Therefore, the fabricated poly-Si TFT is suitable for projection and high density TFT-LCDs.
a-Si AMLCD PDLC Light Valve with 30% Optical Transmittance
H. Murai, N. Nakagawa, K. Nakashima, K. Nakanishi, S.
Hirose, M. Yuki
Advanced Display, Inc., Kumamoto, Japan
S.
Shikama
Imaging Systems Laboratory, Mitsubishi Electric Corp.,
Kyoto, Japan
M. Takada
Materials and Electronic Devices
Laboratory, Mitsubishi Electric Corp., Hyogo, Japan
full paper
A PDLC (Polymer Dispersed Liquid Crystal) light valve addressed by an a-Si TFT array, which has 640x480 pixels in a 3.1 inch diagonal was developed. This light valve has high optical transmittance (about 30%) at intensive incident illumination over 1E6 lux and is used in a projector giving as much as 460 lm with a contrast ratio of over 50.
A 23-cm-Diagonal Bright
Reflective Guest-Host TFT-LCD
H. Kanoh, E. Mizobata, H.
Ikeno, S. Kaneko
NEC Corp., Kanagawa, Japan
full paper
Bright reflective guest-host (GH) TFT-LCDs for portable computers have been realized by the development of a novel reflector structure and GH liquid crystals. These 23-cm-diagonal 400 x 640-pixel displays have 55% reflectivity and a contrast ratio of 50, which compares favorably with a newspaper.
Electrical Properties of Double LDD Poly-Si TFTs with Defect-Tolerant
Redundancy for AMLCDs
M. Kunii, Y. Hayashi, H. Hayashi
Sony Corp., Kanagawa, Japan full
paper
The electrical properties of a polycrystalline silicon thin film transistor (poly-Si TFT) characterized by a double TFT with Lightly Doped Drains (a double LDD-TFT) were investigated. This paper presents defect-tolerant redundancy inherent in the double LDD-TFTs, which eliminates almost all the pixel defects caused by excessive leakage current of TFTs in active matrix liquid crystal displays (AMLCDs)
Bias-Temperature
Instability in Hydrogenated Poly-Si TFTs
N. Bhat, M. Cao, K. C. Saraswat
Stanford University, Stanford, CA full paper
The bias temperature instability in hydrogenated n-and p-channel thin film transistors has been studied. The TFTs were fabricated using a low temperature process compatible with active matrix liquid crystal display application. Significant threshold voltage and subthreshold slope degradation under both +ve and -ve bias stress was observed and a model for the degradation based on interface-state generation which depends on the hydrogen content of the gate dielectric is proposed. The degradation increases with increased hydrogen incorporation and is temperature and electric field activated.
A Gray-Scale Drive Method for
TFT-LCDs with Binary-Value-Output Drivers
H. Okada, T.
Takarada, A. Tomiyoshi, T. Kawaguchi
Sharp Corp., Nara, Japan full paper
A new drive method for TFT-LCDs has been developed that can generate multiple real (non-pseudo) gray-shades with binary-value-output drivers. A 6-bit drive system has been designed and experimentally evaluated. Gray scale voltage sources have been eliminated, and the whole circuitry has been drastically simplified.
A Transmission-Line Approach
for Line-Continuity Testing of Active-Matrix Arrays
S.
L. Wright, R. Nywening
IBM T. J. Watson Research Center, Yorktown
Heights, NY full paper
A simple, relatively fast, and sensitive line resistance test for AMLCD arrays has been developed. In this approach, a number of lines are probed as a group and connected "head to tail" in series to form a transmission line. By measuring groups of lines, the test time is much less than that needed by measuring individual lines. Results have been obtained on 1280(x3) x 1024 SXGA arrays
AMLCD with Integrated Drivers Made with Amorphous-Silicon TFTs
H. Lebrun, F. Maurice, J. Magarino, N. Szydlo
Thomson-LCD,
Moirans, France full paper
Using novel circuit architectures, an AMLCD with integrated drivers using a standard amorphous-silicon (`a-Si) TFT technology has been designed, built, and characterized. This 960 x 560 monochrome light valve operates at a line rate of 16 kHz and can display TV images and achieve a contrast ration of more than 200:1.
A Five-Mask Process to Make Completely Self-Aligned a-Si TFTs with
Laser-Doped Poly-Si Source-and-Drain Regions
R. Kakkad,
Y. Miura, M. Shibusawa, N. Ibaraki
Toshiba Display Device
Engineering Lab., Yokohama, Japan
T. Obara, S. Matsunaka, H. Ito
Toshiba
Manufacturing Engineering Research Center, Yokohama, Japan full paper
A five-mask process has been developed to make completely self-aligned, inverted stagger a-Si TFTs. The five-mask process includes a passivation-layer-patterning process and fabrication of storage capacitors. The source and drain regions of these TFTs were laser-doped and crystallized. This process gave TFTs with mobility close to 1 sq cm/V s. The process is also suitable for high-throughput TFT-LCD manufacturing