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Method of Selective Anodic Oxidation

IP.com Disclosure Number: IPCOM000114234D
Original Publication Date: 1994-Nov-01
Included in the Prior Art Database: 2005-Mar-28
Document File: 4 page(s) / 343K

Publishing Venue

IBM

Related People

Arai, T: AUTHOR

Abstract

Disclosed is a method for the Thin Filmed Transistor (Fig. 1) to proceed selective anodic oxidation and electrode patterning with the same photo resist mask. With this method, a through hole on the oxidized gate metal and a electrode for the storage capacitance can be both made by the same photo resist mask.

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Method of Selective Anodic Oxidation

      Disclosed is a method for the Thin Filmed Transistor (Fig. 1)
to proceed selective anodic oxidation and electrode patterning with
the same photo resist mask.  With this method, a through hole on the
oxidized gate metal and a electrode for the storage capacitance can
be both made by the same photo resist mask.

      Figs. 2 through 4 show this process.  In these Figures, the
upper portion shows the plane view, and the lower portion shows the
cross sectional structure.  First of all, electrode film and gate
metal are deposited, and only gate metal is patterned (Fig. 2; 1st
Photo Etching Process, 2-4).  Indium-Tin-Oxide (ITO) is usually used
as the electrode on Thin Filmed Transistor Process.  This electrode
is required the etching selectivity to the gate metal etchant.  Next,
photo resist is patterned for the through hole and the storage
capacitance (Fig. 3; 2nd Photo Etching Process).  And only electrode
is etched off.  Next, selective anodic oxidation is proceeded by the
same photo resist mask of the electrode etching.  This gate metal is
required etching selectivity to the electrode etchant.  Finally,
photo resist is removed (Fig. 4).

      If the gate metal doesn't have the etching selectivity to the
electrode etchant, it is enough to insert the gate metal between
Metal 1 and Metal 2 (Fig. 2; 1st Photo Etching Process).  Metal 1 and
Metal 2 are required etching selectivity to the electrode etchant.
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