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Laser Crystallization of A-Si after Patterning to Fabricate Poly-Si Thin Film Transistors

IP.com Disclosure Number: IPCOM000116545D
Original Publication Date: 1995-Oct-01
Included in the Prior Art Database: 2005-Mar-30
Document File: 2 page(s) / 34K

Publishing Venue

IBM

Related People

Takeuchi, K: AUTHOR

Abstract

Disclosed is a method to fabricate poly-Si Thin Film Transistors (TFTs) for active matrix TFT display devices. Patterning of semiconductor thin film to make transistor channel region takes place prior to transformation of a-Si into poly-Si by laser irradiation. This leads to uniform TFT characteristics on large area glass substrate because channel region is smaller than laser spot.

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Laser Crystallization of A-Si after Patterning to Fabricate Poly-Si
Thin Film Transistors

      Disclosed is a method to fabricate poly-Si Thin Film
Transistors (TFTs) for active matrix TFT display devices.  Patterning
of semiconductor thin film to make transistor channel region takes
place prior to transformation of a-Si into poly-Si by laser
irradiation.  This leads to uniform TFT characteristics on large area
glass substrate because channel region is smaller than laser spot.

      The Figure summarizes this method.  First, a-Si thin film is
deposited, and TFT channel regions are formed through lithography and
etching techniques, which is very common process in conventional a-Si
TFT fabrication.  Secondly, shots of moderate pulsed laser beam are
irradiated on a-Si channels.  It is very important to keep the edge
of laser spot to the area between channels as shown in the Figure.
By scanning this laser source, all a-Si channels on large area glass
substrate would be transformed into poly-Si.  The rests of process to
form TFTs follow conventional one used in a-Si TFT fabrication.

      This method is applicable to both staggered and
inverse-staggered type poly-Si TFTs.  It is also possible to use more
than one laser beam.