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Method of Anodic Oxidation Using Two Metals

IP.com Disclosure Number: IPCOM000115152D
Original Publication Date: 1995-Mar-01
Included in the Prior Art Database: 2005-Mar-30
Document File: 2 page(s) / 45K

Publishing Venue

IBM

Related People

Arai, T: AUTHOR [+2]

Abstract

Disclosed is a method for the TFT (Thin Filmed Transistor) to partially change the capacitance of the gate insulator. Two metals are used as the gate metal, and anodic oxidized. With this method, it is possible to reduce the capacitance between the Gate line and the Data line, and get a high performance TFT and Cs (Storage Capacitor) on the same time. Figure 1-3 shows this process. First of all, the 1st metal is patterned. The 1st metal constructs the Gate line and the Cs line. Low resistance is required as the Gate line and Cs line. In this case, aluminum (Al) is used as the 1st metal. Next, the 2nd metal is patterned on the place where a large capacitance is required. And finally, the 1st metal and the 2nd metal are anodic oxidized on the same time.

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Method of Anodic Oxidation Using Two Metals

      Disclosed is a method for the TFT (Thin Filmed Transistor) to
partially change the capacitance of the gate insulator.  Two metals
are used as the gate metal, and anodic oxidized.  With this method,
it is possible to reduce the capacitance between the Gate line and
the Data line, and get a high performance TFT and Cs (Storage
Capacitor) on the same time.  Figure 1-3 shows this process.  First
of all, the 1st metal is patterned.  The 1st metal constructs the
Gate line and the Cs line.  Low resistance is required as the Gate
line and Cs line.  In this case, aluminum (Al) is used as the 1st
metal.  Next, the 2nd metal is patterned on the place where a large
capacitance is required.  And finally, the 1st metal and the 2nd
metal are anodic oxidized on the same time.  It is required for the
2nd metal to be oxidized with the 1st metal on the same time, and the
relative dielectric constant of the 2nd metal's oxide is larger than
that of the 1st metal's oxide.  In this case, tantalum (Ta) is used
as the 2nd metal.  These oxide's relative dielectric constant and
growth ratio of the anodic oxidation are as follows.
                                  AlOx    TaOx
  relative dielectric constant      9      14
  growth ratio(angstrom/volt)      23      15
  capacitance rate                0.4   :   1