Method for forming a flexible metal foil substrate display

Abstract

A flexible metal foil substrate organic light emitting diode (OLED) display and a method for forming the same are provided. The method comprises: supplying a metal foil substrate such as titanium (Ti), Inconel alloy, or Kovar, having a thickness in the range of 10 to 500 microns; planarizing the metal foil substrate surface; depositing an electrical isolation layer having a thickness in the range of 0.5 to 2 microns overlying the planarized metal foil substrate surface; depositing amorphous silicon having a thickness in the range of 25 to 150 nanometers (nm) overlying the electrical insulation layer; from the amorphous silicon, forming polycrystalline silicon overlying the electrical insulation layer; forming thin-film transistors (TFTs) in the polycrystalline silicon; and, forming an electronic circuit using the TFTs, such as an OLED display.

Description

RELATED APPLICATIONS [0001] This application is a continuation-in-part of a pending patent application entitled, THIN-FILM TRANSISTORS FORMED ON A METAL FOIL SUBSTRATE, invented by Voutsas et al., Ser. No. 10 / 194,895, filed Jul. 11, 2002. [0002] This application is a Divisional of a pending patent application entitled, FLEXIBLE METAL FOIL SUBSTRATE DISPLAY AND METHOD FOR FORMING SAME, invented by Tolis Voutsas, Ser. No. 10 / 282,744, filed Oct. 28, 2002.BACKGROUND OF THE INVENTION [0003] 1. Field of the Invention [0004] This invention generally relates to organic light emitting diode (OLED) displays and, more particularly, to an OLED display fabricated on a thin metal foil substrate. [0005] 2. Description of the Related Art [0006] As noted in U.S. Pat. No. 6,392,617 (Robert Gleason), arrays of OLEDs are utilized to create two-dimensional flat panel displays. As compared to conventional light emitting diodes (LEDs), which are made of compound semiconductors, the low cost and ease of pa...

AI Technical Summary

Benefits of technology

[0020] The present invention describes a method and process for the fabrication of displays on robust substrates made of metal foils. The invention describes the use of metal foil substrates for the fabrication of poly-Si TFT backplanes, and also the processes that ...

Problems solved by technology

High peak currents are generally undesirable because they reduce the luminous efficiency of available OLEDs.

The voltage on the storage node will typically drop due to leakage through the junction of the address transistor and through the gate dielectric of the drive transistor.

However, one disadvantage of the latter method is that the storage node capacitance within a single pixel is a non-linear function of the voltage when supplied by the gates and junctions of the transistors.

Another disadvantage is that the storage node capacitance of each pixel varies among the pixels in an array.

Unfortunately, current flow through the drive transistor also depends on characteristics of the drive transistor, such as its threshold voltage and transconductance.

These variations, in turn, cause a display to appear non-uniform.

Furthermore, the light intensity for a specified drive current drops as an OLED ages and different OLEDs can degrade at different rates, again causing a display to appear non-uniform.

It is difficult to obtain a tight distribution of threshold voltages in large arrays of thin-film transistors, especially as more transistors are n...

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