Eileen A. Galligan

High-speed signal propagation on lossy transmission lines

This paper addresses some of the problems encountered in propagating high-speed signals on lossy transmission lines encountered in high-performance computers. A technique is described for including frequency-dependent losses, such as skin effect and dielectric dispersion, in transmission line analyses. The disjoint group of available tools is brought together, and their relevance to the propagation of high-speed pulses in digital circuit applications is explained. Guidelines are given for different interconnection technologies to indicate where the onset of severe dispersion takes place. Experimental structures have been built and tested, and this paper reports on their electrical performance and demonstrates the agreement between measured data and waveforms derived from analysis. The paper addresses the problems found on lossy lines, such as reflections, rise-time slowdown, increased delay, attenuation, and crosstalk, and suggests methods for controlling these effects in order to maintain distortion-free propagation of high-speed signals.

Ion beam alignment for liquid crystal display fabrication

The ability to align liquid crystals to a substrate is a critical step in the liquid crystal display (LCD) manufacturing process with the industry standard technique employing a mechanical rubbing technique to accomplish this function. However, mechanical rubbing can result in debris generation contaminating not only the substrate being processed but also the clean room housing the equipment. As such, post-cleaning of the display panels is required to remove the debris from the surface in addition to the physical isolation of the mechanical rubbing equipment within the clean room environment introducing considerable time and expense. In addition, uneven wear of the mechanical roller during the rubbing process may result in localized defects that will not be observed until final inspection of a completely assembled display. We have developed and introduced into LCD manufacturing a non-contact alignment technique utilizing both diamond-like carbon (DLC) and a low energy ion beam (IB). The replacement of the polyimide alignment layer with DLC results in a completely dry processing technique for both the thin film deposition and alignment steps.

MULTI-DOMAIN HOMEOTROPIC LIQUID CRYSTAL DISPLAY BASED ON RIDGE AND FRINGE FIELD STRUCTURE

A ridge and fringe field multi-domain homeotropic (RFFMH) liquid crystal display was demonstrated. The operating principle of this new display mode is the combination effect of a fringe field and ridge structure to control the tilt direction of the liquid crystal molecules when a voltage is applied. No rubbing treatment is required and, with proper compensation films, the display has very wide viewing angles.

Dry Vertical Alignment Method for Multi-domain Homeotropic Thin-Film-Transistor Liquid Crystal Displays

Multi-domain homeotropic liquid crystal alignment has been recognized as an alignment method to achieve wide viewing angle for thin-film-transistor liquid crystal displays (TFT-LCDs). In the past decade, several types of multi-domain homeotropic TFT-LCDs have been well studied. In all these LCDs, a homeotropic polyimide layer is used to align liquid crystal molecules. In this paper, a new homeotropic alignment method-dry deposition vertical alignment (or vacuum deposition vertical alignment) is introduced. We studied several different vacuum deposited vertical alignment materials and one of them was demonstrated on a high resolution ridge fringe-field multi-domain homeotropic (RFFMH) TFT-LCD. This new method has advantages over the conventional polyimide alignment method: it simplifies the manufacturing process by avoiding wet chemical processes and improves the viewing angle by reducing light leakage.

A 10.5-in.-diagonal SXGA active-matrix display

A 157-dot-per-inch, 262K-color, 10.5-in.- diagonal, 1280 × 1024 (SXGA) display has been fabricated using a six-mask process with Cu or Al-alloy thin-film gates. The combination of high resolution and gray-scale accuracy has been shown to render color images and text with paperlike legibility. The low-resistivity gate metallization and trilayer-type TFTs with a channel length of 6-8 µm were fabricated with a six-mask process which is extendible to larger, higher-resolution displays. A combination of double-sided driving and active line repair was used so that open gate lines or data lines did not result in visible line defects. A flexible drive-electronics system was developed to address the display and characterize its performance under different drive conditions.

A six-mask TFT-LCD process using copper-gate metallurgy

— A novel reduced mask process is used to fabricate high-resolution high-aperture-ratio 10.5-in. SXGA (1280 × 1024) displays. The process uses copper gate-metallurgy with redundancy, without the need for extra processing steps. The resulting displays have 150-dpi color resolution, an aperture ratio of over 35%, and excellent image quality, making them the first high-resolution displays that are suitable for notebook applications.

44.1 L: Ridge and Fringe‐Field Multi‐Domain Homeotropic LCD

A ridge and fringe field multi-domain homeotropic (RFFMH) liquid crystal display was demonstrated. The operating principle of this new display mode is the combination effect of a fringe field and ridge structure to control the tilt direction of the liquid crystal molecules when a voltage is applied. No rubbing treatment is required and, with proper compensation films, the display has very wide viewing angles.

56.1: Novel LC Alignment Method using Diamond Like Carbon Film and Ion Beam Alignment

A novel LC alignment method has been developed. In this, the conventional polyimide film and cloth rubbing have been replaced by a diamond-like-carbon film and an ion beam respectively. The novel method has been used in pilot-line manufacturing to produce super high quality panels: 15″ TN mode and 22″ IPS mode. These panels will be demonstrated, and the advantage of new method will be discussed.

Fabrication and performance studies of multilayer polymer/metal interconnect structures for packaging applications

Multilayer copper/polyimide interconnect structures were fabricated using a reactive-ion-etching-based lift-off technique. Conductor cross-sectional area control, planarity, and a gap-free structure were made possible by the use of a novel siloxane-polyimide. The resultant structure consisted of two signal wiring layers between two ground planes with a nominal impedance of 40 Omega . Although redundant metallization processes were found to repair open lines, they resulted in an increase of the number of processing steps and could result in an increase of defects. Stud chain structures were found to survive cooling to 77 K with very little change in their characteristics, while heating of the copper interconnections to 350 degrees C in a reducing environment reduced their resistance by 3%.<<ETX>>

Factors affecting the interconnection resistance and yield in multilayer polyimide/copper structures

The use of a lift-off technique to fabricate a high-density structure consisting of multiple layers of metal/polyimide thin-film structures on a silicon substrate is described. To achieve better performance and high yield, the process design, the processing parameters, the thickness of the Cr/Cu/Cr metallurgy, and the use of suitable polyimide dielectrics, were evaluated. The plasma processing conditions, the types of passivation metals on Cu, and the use of a siloxane-polyimide as the gap-fill/etch-stop material were all shown to play a critical role in affecting the interconnection resistance and yield of the multilayer thin-film structures. By optimizing these parameters the feasibility of fabricating high-density thin-film wiring layers with good yield is demonstrated. >