Thin film transistor substrate, method for manufacturing the same, and liquid crystal display panel

1. A method for manufacturing a thin film transistor substrate including

a plurality of pixel electrodes provided in a matrix,

a plurality of thin film transistors each provided for a corresponding one of the pixel electrodes and connected to the corresponding one of the pixel electrodes, and

a plurality of auxiliary capacitors each provided for a corresponding one of the pixel electrodes,

in which each of the thin film transistors includes

a gate electrode provided on a substrate,

a gate insulating film provided so as to cover the gate electrode,

a semiconductor layer provided on the gate insulating film and having a channel region such that the channel region and the gate electrode overlap with each other, and

source and drain electrodes provided on the semiconductor layer and arranged apart from each other with the channel region being interposed therebetween, the channel region being exposed through the source and drain electrodes, and

each of the auxiliary capacitors includes

a capacitor line made of a material identical to that of the gate electrode and provided in a layer identical to that of the gate electrode,

the gate insulating film provided so as to cover the capacitor line,

the semiconductor layer provided on the gate insulating film so as to overlap with the capacitor line, and

the drain electrode provided on the semiconductor layer and connected to a corresponding one of the pixel electrodes, the method comprising:

a gate layer formation step of forming the gate electrode and a capacitor line on a substrate;

a resist pattern formation step of forming, after the gate insulating film, a semiconductor film made of an oxide semiconductor, and a metal conductive film are formed in this order so as to cover the gate electrode and the capacitor line, a resist pattern on a region of a metal conductive film where the source and drain electrodes are to be formed such that a region to be the channel region and part of a region overlapping with the capacitor line are exposed;

a first etching step of etching part of the metal conductive film exposed through the resist pattern to form the source and drain electrodes and the channel region and expose part of the semiconductor film through the drain electrode;

a second etching step of etching, after the resist pattern formed in the first etching step is reflowed and reformed so as to cover the part of the semiconductor film exposed through the drain electrode and the channel region, part of the semiconductor film exposed through the reformed resist pattern to form the semiconductor layer, thereby forming each of the thin film transistors;

an interlayer insulating film formation step of forming, after the resist pattern used in the second etching step is removed, an interlayer insulating film in which a contact hole is formed so as to reach part of the semiconductor layer exposed through the drain electrode in a region overlapping with the capacitor line; and

a pixel electrode formation step of forming each of the pixel electrodes made of an oxide conductor on the interlayer insulating film to form each of the auxiliary capacitors with each of the pixel electrodes contacting the semiconductor layer.

2. The method of claim 1 , wherein

the semiconductor film is made of an In—Ga—Zn—O based semiconductor.