Large Area Flat Panel Display Research Articles

Reduced off-axis gamma shift of liquid crystal display by intercepting transmittance method

Generally, the brightness and color of one image on a large-area flat panel display are different when people watch a display image under different viewing angles. The gamma shift is used to evaluate the difference of electro-optical performances under different viewing angles, namely the gray-scale display distortion. In order to reduce the gamma shift under the oblique viewing angle, the intercepting transmittance method is proposed and illustrated based on the single-domain in-plane switching blue-phase liquid crystal display (IPS-BPLCD). The results show that the off-axis image distortion index (the quantitative evaluation index of gamma shift) can be reduced by ~72% if the transmittance ratio reduces from 100% to 80% for the IPS-BPLCD with a straight electrode structure. Moreover, the zigzag electrode structure is used as the reference to illustrate the merits of the proposed method. As a result, the operating voltage of the IPS-BPLCD can be reduced by >20%, and the off-axis image distortion index is reduced by ~47% compared with the zigzag electrode structure. Besides this, the effects of the proposed method on contrast ratio, operating voltage and color difference of IPS-BPLCD are investigated as well. In fact, the proposed method is also useful for other LCD modes and electro-optical devices to achieve wide and uniform viewing angles.

ChemInform Abstract: Recent Progress in Phosphorescent Organic Light‐Emitting Devices

AbstractReview: 98 refs.

Linear inductive antenna design for large area flat panel display plasma processing

Two different internal-type linear inductive antenna arrangements, that is, parallel and anti-parallel antenna arrangements having different current directions between adjacent antennas were investigated for a large area plasma source having the size of 1020 mm × 830 mm. The electric field profile and plasma density of Ar calculated by the F2L code showed consistent results with the experimental results on the plasma density and processing results. The results showed that the anti-parallel antenna arrangement showed better plasma uniformity compared to the parallel antenna arrangement due to the destructive E z -field between adjacent antennas even though the destructive E z -field decreases the plasma density at the center of the chamber.

Scalable internal linear double comb-type inductively coupled plasma source for large area flat panel display processing

The characteristics of a large area internal linear inductively coupled plasma source of 2750 mm×2350 mm have been studied using a linear antenna with a double comb-type parallel connection. Using the ICP with the double comb-type linear antenna, a plasma density of 8×1010/cm3 and a power transfer efficiency of approximately 82% could be obtained at about 10 kW of rf power and with 5 mTorr Ar. Low plasma potentials and low electron temperatures decreasing from 45 to 20 V and from 3.33 to 2.78 eV, respectively, could be obtained as the operation pressure was increased from 5 to 20 mTorr at 10 kW of rf power. The measured plasma uniformity on the substrate size of 7th generation (2300 mm×2000 mm) at 5 kW of rf power and with 15 mTorr Ar was approximately 14% and the photoresist etch uniformity measured using 15 mTorr Ar/O2(7:3) at 8 kW of rf power was about 12.5%. Therefore, it is believed that the double comb-type parallel connection can be successfully applicable to the large area flat panel display processing.

Theoretical investigation of the influence of nozzle diameter variation on the fabrication of thin film transistor liquid crystal display color filters

Printing technologies have gained widespread attention from industry as an alternative to expensive photolithographic processes. Among the various kinds of printing technologies, piezoelectric drop-on-demand (piezo-DOD) inkjet printing is regarded as a promising patterning method because of its inherent simplicity and very low levels of material waste generation, especially for display industries such as thin film transistor liquid crystal displays and polymer light emitting diode displays. However, its key engineering difficulty is the variation of droplet volume across the nozzles in a piezo-DOD inkjet printhead, which causes visible swathe marks on a printed display screen. In this paper, it is suggested that the occurrence of these swathe marks could result from the influence of the mechanical nozzle tolerance, i.e., the variation in nozzle diameter of the piezo-DOD printhead. The effect of the mechanical nozzle tolerance on droplet velocity and volume is investigated using mathematical models. Finally, the future research and development direction of piezo-DOD inkjet printing technology for the large area flat panel display industry are discussed.

Characteristics of Large Area Inductively Coupled Plasma Using a Multiple Linear Antennas with U-Type Parallel Connection for Flat Panel Display Processing

In this study, the characteristics of large area internal linear inductively coupled plasma (ICP) sources of 1,020×920 mm2 (substrate area is 880×660 mm2) were investigated using a multiple linear antennas with U-type parallel connection. Using the multiple linear antennas with U-type parallel connection, a high plasma density of 2×1011 cm-3 and a high power transfer efficiency of about 88% could be obtained at 5 kW of RF power and with 20 mTorr Ar. A low plasma potential of less than 26 V and a low electron temperature of 2.6–3.2 eV could be also obtained. The measured plasma uniformity on the substrate size of fourth generation (880×660 mm2) was about 4%, therefore, it is believed that the multiple linear antennas with U-type parallel connection can be successfully applicable to the large area flat panel display processing.

Characteristics of Parallel Internal-Type Inductively Coupled Plasmas for Large Area Flat Panel Display Processing

The development of a large-area high-density plasma source is desired for various plasma processes from microelectronics fabrication to flat panel display (FPD) device fabrication. In this study, using a parallel internal-type (double comb-type) inductively coupled plasma source having the size of 1020 mm×830 mm, high density plasmas on the order of 2.2×1011 cm-3 could be obtained with Ar at 5000 W inductive power. Plasma uniformity on the substrate in the size of 920 mm×730 mm decreased with the increase in inductive power and was about 8% when the inductive power was 5000 W. When SF6 was used to etch SiO2 using the source, the SiO2 etch rate higher than 2000 Å/min with an etch uniformity of about 6% could be obtained at 5000 W inductive power, -350 V bias voltage, and 15 mTorr operating pressure.

Linear internal inductively coupled plasma (ICP) source with magnetic fields for large area processing

A large-area (830×1020 mm) inductively coupled plasma source with internal straight antennas was developed for large area flat panel display (FPD) etch process applications and the effects of magnetic fields employing permanent magnets on the plasma characteristics were investigated. Using straight antennas connected in series without the magnetic field, high-density plasmas on the order of 10 11 cm −3 could be obtained by applying 1500 W of r.f. power to the antennas. By employing the magnetic fields perpendicular to the antenna currents using permanent magnets, improved plasma characteristics such as increase of ion density and decrease of both electron temperature and plasma potential could be achieved in addition to the stability of the plasma possibly due to the reduction of the electron loss. However, the application of the magnetic field decreased the plasma uniformity slightly even though the uniformity within 10% could be maintained in the 800 mm processing area.

Interference microscopy for nanometric surface microstructure analysis in excimer laser processing of silicon for flat panel displays

The rapid control of laser crystallisation during in-line large area flat panel display fabrication using polysilicon (poly-Si) thin-film transistors (TFT’s) is of growing importance. In this work, the microstructural analysis of the laser irradiated area has been studied with atomic force microscopy (AFM) and phase stepping microscopy (PSM), the latter being an automated mode of interference microscopy that allows the rapid and non-destructive measurement of nanometric surface morphology. The evolution of the crystallisation process in amorphous silicon (a-Si) thin films irradiated using large and long duration (200 ns) excimer laser (308 nm) pulses as a function of different key parameters such as the laser fluence, the beam homogeneity and the number of laser shots has been studied. We show that PSM, although having a lower lateral resolution than AFM, is capable of detecting the important super lateral growth (SLG) region. From the comparison of the results obtained by interference microscopy and AFM, the PSM technique has been shown to be an interesting alternative way that could be used for the quantitative calibration of the laser annealing process in an industrial environment.

Chimney-Shaped and Plateau-Shaped Gate Electrode Field Emission Arrays

AbstractA triode structure of chimney-shaped field emitter arrays is proposed in this article. This triode structure includes the chimney-shaped emitter, thermal oxidation dioxide, and the plateau-shaped singlecrystalline silicon gate electrode. For the application of the matrix-addressable and large area flat panel display, the uniform structure of the emitters and the yield become critical manufacturing issues when attempting to control nano-meter size features. The uniformity and yield of the chimney-shaped emitters are very well controlled. The nano-sized gate-to-emitter separations can be created by the changing thickness of the insulator. The uniformity of the insulator and emitter material can be controlled within 3% which can be obtained by most large area thin film deposition tools, not by photolithography.

Chimney-Shaped and Plateau-Shaped Gate Electrode Field Emission Arrays

AbstractA triode structure of chimney-shaped field emitter arrays is proposed in this article. This triode structure includes the chimney-shaped emitter, thermal oxidation dioxide, and the plateau-shaped singlecrystalline silicon gate electrode. For the application of the matrix-addressable and large area flat panel display, the uniform structure of the emitters and the yield become critical manufacturing issues when attempting to control nano-meter size features. The uniformity and yield of the chimney-shaped emitters are very well controlled. The nano-sized gate-to-emitter separations can be created by the changing thickness of the insulator. The uniformity of the insulator and emitter material can be controlled within 3% which can be obtained by most large area thin film deposition tools, not by photolithography.

Etching characteristics of tin oxide thin films in argon–chlorine radio frequency plasmas

We have developed an etch process suitable for high resolution transparent conductive oxide patterning with high etch rates, up to 70 nm/min, and applicability to large area flat panel display substrates. It was found that the addition of small amounts of Cl2 significantly enhanced the etch rate compared to addition of pure argon but that beyond 25% Cl2 the rate tended to fall. There is a significant loading effect where the etch rate approximately doubled for exposed tin oxide areas between 80% and 10% of the substrate area. This loading sensitivity was found to increase with increasing power and decreasing Cl2 concentration. It was also observed that local changes in pattern dimensions affected the uniformity of the etch rate. A large photoresist etch rate was observed between one and three times that of the tin oxide and it decreased as the area of photoresist coverage increased. Linewidth loss, up to 4 μm at high powers, was overcome using improved ultraviolet exposure, leading to feature resolution capabilities of <5 μm. Etch rate inhomogeneity was also observed on a local scale, possibly due to redeposition of sputtered photoresist. Overetching, however, ensures rapid clearing of tin oxide islands without damage to the underlying SiO2 buffer layer.

Novel high-density plasma tool for large area flat panel display etching

A novel dry etch tool—large area source supported ion etching (LASSIE)—has been developed appropriate for the processing of substrate sizes of presently up to 600×400 mm2. The plasma is produced through an array of four inductively coupled plasma sources driven by one common 13.56 MHz generator. A second rf generator serves for substrate biasing. Plasma diagnostic data suggest that LASSIE has strong capabilities for future large area etch applications avoiding several drawbacks of conventional reactive ion etching (RIE) in parallel-plate reactors. In particular considerably higher etch rates are to be expected since the plasma densities are roughly one order of magnitude higher than in conventional RIE. In addition the processing will be more flexible and better controlled due to the decoupling of plasma densities and ion bombardment energies. A scale-up with respect to the processing of wafer sizes larger than presently envisaged is easily achieved by the LASSIE concept.

Thin-film video scanner and driver circuit for solid-state flat-panel displays

A thin-film scanner circuit which greatly reduces the number of external lead connections to a large-area flat-panel display, while at the same time providing both the scanning (addressing) function and the video driver function, has been successfully fabricated. The circuit, which can handle both TV (analog) and alphanumeric (digital) type video, also performs line storage so that the incoming serial video can be presented to the display panel in line-at-a-time fashion Vacuum-deposited CdSe thin-film transistors (TFT's), operating in a digital switching mode, are used in conjunction with thin-film storage capacitors to convert the input video into 112 parallel output video columns. Measurements of actual circuit parameters indicate that the scanner can easily operate at real-time TV rates.