Thin film transistor with tapered electrode structure and manufacturing method of the same

A thin film transistor comprising: a substrate; a gate electrode formed on said substrate; an insulating film formed on a top surface of said gate electrode and said substrate; a semiconductor film formed on said insulating film; a source electrode partially connected to said semiconductor film; and a drain electrode partially connected to said semiconductor film, wherein at least one of said gate electrode, said source electrode and said drain electrode has side faces tapered outwardly from a top surface thereof in a direction towards said top surface of said substrate, is composed of one material, and has a prescribed physical property which changes in a direction perpendicular to a top surface thereof, so that an etching rate is changed in said direction.

A thin film transistor comprising: a substrate; a gate electrode formed on said substrate; an insulating film formed on a top surface of said gate electrode and said substrate; a semiconductor film formed on said insulating film; a source electrode partially connected to said semiconductor film; and a drain electrode partially connected to said semiconductor film, wherein at least one of said gate electrode, said source electrode and said drain electrode has side faces tapered outwardly from a top surface thereof in a direction towards said top surface of said substrate, is composed of one material, and has a prescribed physical property which changes continually in a direction perpendicular to a top surface thereof so that an etching rate and an atomic density thereof is changed in said direction and which changes such that atomic density changes in said direction.

A thin film transistor comprising: a substrate; a gate electrode formed on said substrate; an insulating film formed on a top surface of said gate electrode and said substrate; a semiconductor film formed on said insulating film; a source electrode partially connected to said semiconductor film; and a drain electrode partially connected to said semiconductor film, wherein at least one of said gate electrode, said source electrode and said drain electrode has side faces tapered outwardly from a top surface thereof in a direction towards said top surface of said substrate, is composed of one material, and has a prescribed physical property which changes continually in a direction perpendicular to a top surface thereof so that an etching rate and an atomic density thereof is changed in said direction and which changes such that crystal orientation changes in said direction.

A thin film transistor comprising: a substrate; a gate electrode formed on said substrate; an insulating film formed on a top surface of said gate electrode and said substrate; a semiconductor film formed on said insulating film; a source electrode partially connected to said semiconductor film; and a drain electrode partially connected to said semiconductor film, wherein at least one of said gate electrode, said source electrode and said drain electrode has side faces tapered outwardly from a top surface thereof in a direction towards said top surface of said substrate, is composed of one material, and has a prescribed physical property which changes gradually in a direction perpendicular to a top surface thereof so that an etching rate and an atomic density thereof is changed in said direction and which changes such that atomic density changes in said direction.

A thin film transistor comprising: a substrate; a gate electrode formed on said substrate; an insulating film formed on a top surface of said gate electrode and said substrate; a semiconductor film formed on said insulating film; a source electrode partially connected to said semiconductor film; and a drain electrode partially connected to said semiconductor film, wherein at least one of said gate electrode, said source electrode and said drain electrode has side faces tapered outwardly from a top surface thereof in a direction towards said top surface of said substrate, is composed of one material, and has a prescribed physical property which changes gradually in a direction perpendicular to a top surface thereof so that an etching rate and an atomic density thereof is changed in said direction and which changes such that crystal orientation changes in said direction.

A thin film transistor comprising: a substrate; a gate electrode formed on said substrate; an insulating film formed on a top surface of said gate electrode and said substrate; a semiconductor film formed on said insulating film; a source electrode partially connected to said semiconductor film; and a drain electrode partially connected to said semiconductor film, wherein at least one of said gate electrode, said source electrode and said drain electrode has side faces tapered outwardly from a top surface thereof in a direction towards said top surface of said substrate, and comprises a two-layer electrode, each electrode layer of said two-layer electrode is composed of one material, and has a prescribed physical property which changes in a direction perpendicular to a top surface thereof, so that an etching rate is changed in said direction.

A method of manufacturing a thin film transistor comprising: a substrate, a gate electrode formed on said substrate, an insulating film formed on said fate electrode and said substrate except for whole of outer surface of said gate electrode, a semiconductor film formed on said insulating film, a source electrode partially connected to said semiconductor film, a drain electrode partially connected to said semiconductor film, wherein in at least one electrode of said gate electrode, said source electrode and said drain electrode, end portion of said at least on electrode is tapered in such a manner that a thickness decreases in a direction toward end face of said at least one electrode, said at least one electrode being composed of one material, and prescribed physical property of said at least one electrode being changed in a direction perpendicular to a surface of said at least on electrode comprising steps of: (a) changing said prescribed physical property of said at least one electrode in a direction perpendicular to a surface of said at least one electrode, so that an etching rate of said at least one electrode is changed in said direction, and (b) etching said at least one electrode to be tapered.