PEP Reduction Using Developed Photo Resist Patterning

PEP Reduction Using Developed Photo Resist Patterning

   Disclosed is a method to make pixel ITO (Indium Tin Oxide)
and aluminum data bus line only with one PEP.(Photo Etching Process)
As the PAG (photo- acid generator) of chemically amplified photo
resist is active even after post bake, UV (Ultra Violet) light
exposure after developing process weaken the adhesion between ITO and
photo resist and the resist pattern is detached from the substrate.
UV light exposure using photo mask after wet etching provides the
detachment of the desired area of the photo resist and the pixel ITO
and aluminum data bus line can be formed only with one PEP.

   Fig.1 shows the method to make pixel electrode and data
bus line with only one PEP.  ITO, Molybdenum and Aluminum are
deposited by sputtering on a glass substrate.(Fig. 1-a)
Negative-type chemically amplified photo resist is coated on the
substrate.  (Fig. 1-b) The pixel area and data bus line area are
exposed to UV light and the substrate is baked.  (Post Exposure Bake)
Developing the photo resist (Fig. 1-c), wet etching of
Aluminum/Molybdenum/ITO is carried out.

   By the exposure to UV light of pixel area, acid is created
from the PAG in the photo resist, and as the surface of the ITO is
etched, the adhesion between the photo resist and ITO is
deteriorated and the photo resist is detached from ITO during wet
etching.  As the pixel area does not have the photo resist any more,
aluminum and molybdenum in pixel area are etched o...