3.3: Display Driver Circuits Fabricated on Flexible Stainless Steel Foils

Abstract

This paper discusses the design and fabrication of digital circuits (primarily shift registers) for display and other active‐matrix driving applications on flexible substrates. The unique advantages of the substrate material and their relation to circuit performance are indicated. A high temperature fabrication process for laser annealed polycrystalline silicon MOS transistors on stainless steel foils is outlined, resulting in effective mobility values up to 267cm2/Vs for n‐channel and 88cm2/Vs for p‐channel devices. Transistor CMOS inverters with a minimum propagation delay of 1.02ns per inverter stage are reported. Both static and dynamic register designs with a high degree of integration are reported, having maximum operating frequencies up to 1.5MHz and 2.5MHz respectively, at supply voltages of 10V or less. These results constitute the first realization of this level of performance and complexity on flexible substrates, and demonstrate the feasibility of high‐speed digital circuitry on thin foils suited for ‐ but not limited to‐ active matrix array driving.

100‐MHz CMOS circuits directly fabricated on plastic using sequential laterally solidified silicon

“…Metal foils such as stainless steel allow high processing temperatures and, as a result, most LTPS techniques developed for glass and a range of microelectronic device fabrication processes can be applied to the fabrication of TFTs on metal foils. [10][11][12] Other benefits over polymer substrates include high dimensional stability and low permeability to oxygen and water vapor. On the other hand, metals are opaque (preventing their use for transmissive displays), heavier than polymers, and electrically conductive (introducing parasitic capacitances).…”

Low-Temperature Polycrystalline Silicon Thin-Film Transistors and Circuits on Flexible Substrates

“…[36][37][38] The best results to date correspond to n-channel mobility of up to 267 cm 2 /V s and p-channel mobility of 88 cm 2 /V s with a highest reported process temperature of 400°C. [36][37][38] The best results to date correspond to n-channel mobility of up to 267 cm 2 /V s and p-channel mobility of 88 cm 2 /V s with a highest reported process temperature of 400°C.…”