Multilayer indium-tin-oxide (ITO)–Ag–ITO stacks were evaluated as transparent conductors for flexible organic light-emitting diode (OLED) displays. The ITO–metal–ITO (IMI) samples exhibited significantly reduced sheet resistance over ITO and greater than 80% optical transmission. The IMI films deposited on plastic substrates showed dramatically improved mechanical properties when subjected to bending both as a function of radius of curvature as well as number of cycles to a fixed radius. OLEDs were fabricated on both ITO and IMI anodes, and the devices with IMI anodes showed improved performance at current densities greater than 1mA∕cm2 due to the improved conductivity of the anode.

Two different approaches to automated bend testing of flexible substrates for display applications were implemented and characterized: a conventional collapsing radius geometry and a novel technique called the "X-Y-θ" geometry. Indium tin oxide (ITO) coated polymer substrates were used to compare the performance of the two automated systems by in-situ electrical-resistance measurements. Manual bending on fixed-diameter mandrels was used to help interpret the results. The advantages and drawbacks of the two systems for providing information of practical use to flexible display R&D are discussed.

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The use of brittle materials in flexible displays requires the understanding of the mechanical limitations of the materials and the various display architectures. We discuss various approaches to mechanical bend tests for components of flexible displays and describe a new test method based on a three-axis motion. We discuss the mechanical limitations of indium tin oxide (ITO) as a transparent conductor, and present results for a more mechanically robust multilayer transparent conductor made of an ITO-metal-ITO (IMI) stack. The IMI structures showed dramatically improved mechanical properties when subjected to bending both as a function of radius of curvature as well as number of cycles to a fixed radius. Organic light emitting devices fabricated on IMI anodes showed improved performance compared with those made on ITO anodes at current densities greater than 1 mA/cm2 due to the improved conductivity of the anode. We discuss the difficulties in analysis of the mechanical failure of transparent thin film permeation barriers. We present a novel approach for etching barrier-coated polymer substrates such that film cracking is readily visible. We report on the bend test results for sputter- deposited SiOxNy films.

A TSV test vehicle lot and 3D interposer demonstration lot were successfully fabricated and tested. Fabrication of the TSV test vehicle was accomplished using three process (mask) levels – front-side metal, backside TSV, and backside metal. The TSVs were formed using a vias-last approach with a nominal TSV size of 100μm, and an aspect ratio of 6:1. DRIE bottom clear process conditions were tested which produced 100 % yield on TSV contact chains with up to 540 vias. In addition, optimum process conditions resulted in a TSV resistance of 29 mΩ, and sufficient TSV isolation resistance (> 1MΩ) for the target application. The interposer demonstration lot incorporated five front-side metal levels, one TSV level, and two backside metal levels. The first four metal layers (M1-M4), utilized 2μm Cu and 2μm oxide layers. Metal layers M2-M4 were fabricated using a self-aligned dual damascene process. Each wafer in the demonstration lot had 4 MLM contact chain test structures, with 26400 vias per structure. On two wafers, 100 % yield was achieved on the MLM contact chains. For the dual damascene levels, average contact resistance per via was 4 mΩ. Functional testing was performed on two die from the demonstration lot (die size = 4 cm X 3.7 cm). Over 99 % of the functional nets (circuit paths) passed. Yield on large area test capacitors, tested at wafer level, exceeded 80 %.