Browse Prior Art Database

Wet Etchant for Molybdenum Having High Selectivity Against Aluminum

IP.com Disclosure Number: IPCOM000109266D
Original Publication Date: 1992-Aug-01
Included in the Prior Art Database: 2005-Mar-23
Document File: 2 page(s) / 64K

Publishing Venue

IBM

Related People

Uchida, T: AUTHOR

Abstract

In Thin Film Transistor/Liquid Crystal Display (TFT/LCD) fabrication, three-layer structure (Mo/Al/Mo) is the typical application for signal lines and electrodes. They are formed by wet etching using the following wet etchant solution (A) which is effective for etching both molybdenum and aluminum. In the three-layer structure, the bottom molybdenum prevents diffusion of aluminum in amorphous silicon and the top molybdenum has an effect for suppressing undercutting of the bottom molybdenum electrochemically during etching of the three layers.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 78% of the total text.

Wet Etchant for Molybdenum Having High Selectivity Against Aluminum

       In Thin Film Transistor/Liquid Crystal Display (TFT/LCD)
fabrication, three-layer structure (Mo/Al/Mo) is the typical
application for signal lines and electrodes.  They are formed by wet
etching using the following wet etchant solution (A) which is
effective for etching both molybdenum and aluminum.  In the
three-layer structure, the bottom molybdenum prevents diffusion of
aluminum in amorphous silicon and the top molybdenum has an effect
for suppressing undercutting of the bottom molybdenum
electrochemically during etching of the three layers.

      After forming signal lines and electrodes, top molybdenum
should be etched because it causes the following two problems.
First, if molybdenum is exposed during n+a-Si dry etching process,
channel region will be contaminated by molybdenum and that causes a
current leakage in TFT.  Secondly, molybdenum is easy to oxidize and
that makes upper layer (SiNx) adhesion worse.  The following wet
etchant solution (A) is not suitable for etching the top molybdenum
because it can etch aluminum, too, and it makes undercutting of the
bottom molybdenum after etching the top molybdenum.

      The following wet etchant solution (B) has been found effective
for etching the top molybdenum of the three layers.  As this etchant
contains a little phosphoric acid, etching rate for aluminum is very
slow.  And the undercutting of the bottom molybdenum is ver...