Thin-film transistor and method for manufacturing same
AssigneeNEC LCD Technologies, Ltd.
InventorHiroshi Okumura
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Abstract
A thin-film transistor is formed by a polycrystalline silicon film having a thin-film part and a thick-film part, the thin-film part minimally being used as a channel part. The polycrystalline silicon film is formed by laser annealing with an energy density that completely melts the thin-film part but does not completely melt the thick-film part. Because large coarse crystal grains growing from the boundary between the thin-film part and the thick-film part form the channel part, it is possible to use a conventional laser annealing apparatus to easily achieve high carrier mobility and low leakage current and the like.
Claims23
A thin-film transistor which comprising a polycrystalline silicon film layer formed on a substrate, a gate electrode formed on said polycrystalline silicon film layer via a gate insulation layer and source and drain electrodes both being arranged on both sides of said gate electrode and being connected to said polycrystalline silicon film layer, and wherein a part of said polycrystalline silicon film layer comprising a thin-film part and a thick-film part and at least a part of said thin film part being minimally used as a channel part of said transistor, and further wherein said thin-film part comprising large coarse crystal grains.
A thin-film transistor which comprising a polycrystalline silicon film layer formed on a substrate, a gate electrode formed on said polycrystalline silicon film layer via a gate insulation layer and source and drain electrodes both being arranged on both sides of said gate electrode and being connected to said polycrystalline silicon film layer, and wherein a part of said polycrystalline silicon film layer comprising a thin-film part and a thick-film part and at least a part of said thin film part being minimally used as a channel part of said transistor, and further wherein at least a portion of said thin-film part is in fully melted condition, while at least a portion of said thick-film part is in not fully melted condition.
A thin-film transistor comprising:
- a polycrystalline silicon film comprising a thin-film part and a thick-film part, said thin-film part being minimally used as a channel part,
- wherein said polycrystalline silicon film is formed by laser annealing with an energy density that completely melts said thin-film part but does not completely melt said thick-film part.
A thin-film transistor according to the present invention 11, wherein said energy density completely melting said thin-film part is an energy density at least as great as a micro-crystallization threshold value and less than an abrasion threshold value of said thin-film part and wherein said energy density not completely melting said thick-film part is an energy density at least as great as the poly-crystallization threshold value and less than the micro-crystallization threshold value of the thick-film part.
A method for manufacturing a thin-film transistor which comprising a polycrystalline silicon film layer formed on a substrate, a gate electrode formed on said polycrystalline silicon film layer via a gate insulation layer and source and drain electrodes both being arranged on both sides of said gate electrode and being connected to said polycrystalline silicon film layer, said method comprising he steps of;
- forming a thin-film part and a thick-film part of an amorphous silicon film on a substrate;
- polycrystallizing said thin-film part and said thick-film part by laser annealing said amorphous silicon film using an energy density completely melting said thin-film part and not completely melting said thick-film part;
- and
- forming a thin-film transistor with said thin-film part as at least a channel part.
Dependencies are inferred from the claim text.