Liquid crystal display device and a manufacturing method of the same
A four-mask process and a three-mask process proposal are constructed for a TN-type liquid crystal display device and an IPS-type liquid crystal device in which the formation of a passivation insulating layer is not required by streamlining the formation of a scan line and a pseudo-pixel element, both comprising a laminate made of a transparent conductive layer and a metal layer, at the same time and the formation of the transparent conductive pixel electrode by removing the metal layer on the pseudo-pixel electrode at the time of the formation of the opening in the gate insulating layer, by streamlining the treatment of the formation process of the contact and the formation process of the protective insulating layer using one photomask due to the introduction of half-tone exposure technology, and the formation of source-drain wires for etch-stop type insulating gate-type transistor using a photosensitive organic insulating layer and leaving the photosensitive organic insulating layer unchanged on source-drain wires or on the source wire (signal line), or by forming an anodized layer, which is an insulating layer, on source-drain wires.
1. A method for manufacturing a liquid crystal display device in which liquid crystal is filled between 1) a first insulating substrate in which unit pixels are arranged in a 2-dimensional matrix on a principal plane, having at least an insulating gate transistor, a scan line doubling as a gate electrode and a signal line doubling as a source wire of the insulating gate transistor, and a pixel electrode connected to a drain, and 2) a second insulating substrate or a color filter opposing the first insulating substrate, the manufacturing method comprising the steps of:
forming the scan line on a main surface of the first insulating substrate,
sequentially depositing one or more gate insulating layers, a first amorphous silicon layer with absence or near absence of impurities, and a protective insulating layer,
forming a photosensitive resin pattern with an opening at the scan line outside an image display area and with a thickness at the protective insulating layer area above the gate electrode thicker than in other areas,
removing the protective insulating layer, the first amorphous silicon layer, and the gate insulating layer, within the opening and to expose part of the scan line,
reducing the thickness of the photosensitive resin pattern to expose the protective insulating layer,
leaving the protective insulating layer narrower than the gate electrode on the first amorphous silicon layer above the gate electrode, using the photosensitive resin pattern that has been reduced in thickness as mask, and to expose the first amorphous silicon layer,
removing the photosensitive resin pattern that has been reduced in thickness, and depositing a second amorphous silicon layer including impurities, and
depositing one or more second metal layers including a heat resistant metal layer to form the source wire and the drain wire with a laminate of the second metal layer and the second amorphous silicon layer.
2. The liquid crystal display device according to claim 1 , wherein said unit pixel further comprises a counter electrode separated at a prescribed distance from said pixel electrode.