The Reactive Ion Etching of Transparent Electrodes for Flat Panel Displays Using Ar / Cl2 Plasmas

Abstract

Large area flat panel displays require high resolution patterning of transparent and high conductivity metal oxides, but the reliability of standard chemical etch techniques at high resolution is inadequate. Tin oxide (SnO2) is a viable alternative to standard In203:Sn (ITO) over large areas but has been ignored due to the lack of a suitable etch process. We have developed an Ar/CI~ reactive ion etch process capable of etching 4 ~m feature sizes and resolutions of 300 lines per inch with rates of up to 90 nm min -1. Emission spectroscopy showed that atomic chlorine is a strong candidate for the active species and that volatile tin chlorides were generated as etch products. Furthermore, the presence of impurity species, particularly hydrogen, was found to be beneficial to the etch rate. Near etch completion, a dramatic decrease in atomic tin emission was observed along with an increase in C1 emission intensity. The etch rate for tin oxide using Ar/C12 was higher than those obtained for ITO using alcohol-based plasmas without the polymer deposition normally associated with organic gas plasmas. Thus the use Ar/C12 etching of SnO2 can provide high resolution transparent conductive electrodes that are uniform over a large area.

Low resistance transparent electrodes for large area flat display devices

“…Loading effects require this value to be adjusted upwards for lower fill factors. 9 The resist was deposited using a large area flood and drain system that allows uniform thickness control from 0.5 to 2 m. The initial thickness was adjusted to account for resist loss during the etch process and the optimum postetch thicknesses were found to be 450 and 800 nm for the copper and aluminum processes, respectively. An increase in the adhesion of the aluminum, typically about 50 kg/cm 2 , to the roughened surface of the plasma bombarded resist was found to enhance the lift-off compared to a number of nonplasma chemical etch processes investigated.…”

Microstructural evolution of oxides and semiconductor thin films

“…Tin oxide thin films are technologically important materials and find applications in areas such as electroluminescent displays [3], heat reflectors [4], mechanical surface coatings [5] and sensors [6]. In a previous work, the sensitivity enhancement of porous SnO 2 -based elements by small grain size effects has been well investigated by Xu et al [7].…”

Nanoparticle and nanosphere mask for etching of ITO nanostructures and their reflection properties

“…The preparation process for widely used Si, ZnO, and ITO nanostructures depends on the material. Si nanostructures can be obtained through CVD processes in the form of Si nanowires , or wet chemical etching processes employing Au or Ag, or nanosphere lithography‐based dry etching process ; similarly, ZnO nanostructures can be grown through CVD processes or solution process in the format of ZnO nanowires, or nanosphere lithography‐based dry etching process ; comparatively, ITO nanostructures can be prepared through Au catalytic growth , however there are only a few reports on plasma etching process for ITO‐based nanostructures , although there are many studies on plasma etching of ITO films, which can employ same etching chemistry as that used in etching of ZnO . Metal nanoparticles have been used for near‐field optical lithography , and nanosphere lithography is an economical technique to generate periodic vertical arrays, compared to deep ultraviolet lithography, electron beam lithography, or nanoimprinting .…”