Method for manufacturing semiconductor device
First Claim
1. A method for manufacturing a semiconductor device comprising:
- forming a semiconductor region comprising silicon over a substrate;
forming a barrier film covering the semiconductor region;
forming a heat retaining film over the barrier film so that the heat retaining film covers top surface and side surfaces of the semiconductor region through the barrier film;
after forming the heat retaining film, crystallizing the semiconductor region by scanning a laser beam from one edge to another of the semiconductor region from the substrate side;
after crystallizing the semiconductor region, removing the heat retaining film and the barrier film; and
after removing the heat retaining film, etching the semiconductor region in a manner that a scanning direction of the laser beam and a channel length direction of a thin film transistor are arranged in the same direction.
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Abstract
It is an object of the invention to provide a technique forming a crystalline semiconductor film whose orientation is uniform by control of crystal orientation and obtaining a crystalline semiconductor film in which concentration of an impurity is reduced. A configuration of the invention is that a first semiconductor region is formed on a substrate having transparent characteristics of a visible light region, a barrier film is formed over the first semiconductor region, a heat retaining film covering a top and side surfaces of the first semiconductor region is formed through the barrier film, the first semiconductor region is crystallized by scanning of a continuous wave laser beam from one edge of the first semiconductor region to the other through the substrate, the heat retaining film and the barrier film are removed, then a second semiconductor region is formed as an active layer of TFT by etching the first semiconductor region. A pattern of the second semiconductor region formed by etching is formed in a manner that a scanning direction of the laser beam and a channel length direction of the TFT are arranged in almost the same direction in order to smooth drift of carriers.
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Citations
48 Claims
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1. A method for manufacturing a semiconductor device comprising:
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forming a semiconductor region comprising silicon over a substrate;
forming a barrier film covering the semiconductor region;
forming a heat retaining film over the barrier film so that the heat retaining film covers top surface and side surfaces of the semiconductor region through the barrier film;
after forming the heat retaining film, crystallizing the semiconductor region by scanning a laser beam from one edge to another of the semiconductor region from the substrate side;
after crystallizing the semiconductor region, removing the heat retaining film and the barrier film; and
after removing the heat retaining film, etching the semiconductor region in a manner that a scanning direction of the laser beam and a channel length direction of a thin film transistor are arranged in the same direction. - View Dependent Claims (2, 3, 4, 5, 35, 41)
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6. A method for manufacturing a semiconductor device comprising:
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forming a semiconductor region comprising silicon over a substrate;
forming a barrier film covering the semiconductor region;
forming a heat retaining film over the barrier film so that the heat retaining film covers top surface and side surfaces of the semiconductor region through the barrier film;
after forming the heat retaining film, crystallizing the semiconductor region by scanning a laser beam from one edge to another of the semiconductor region from the substrate side;
after crystallizing the semiconductor region, removing the heat retaining film;
after removing the heat retaining film, forming an amorphous semiconductor film over the semiconductor region;
after forming the amorphous semiconductor film, segregating a metallic element included in the semiconductor region to the amorphous semiconductor film by heat treatment;
after segregating the metallic element, removing the amorphous semiconductor film and the barrier film; and
after removing the amorphous semiconductor film, etching the semiconductor region in a manner that a scanning direction of the laser beam and a channel length direction of a thin film transistor are arranged in the same direction. - View Dependent Claims (7, 8, 9, 10, 36, 42)
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11. A method for manufacturing a semiconductor device comprising:
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forming an amorphous semiconductor film comprising silicon over a substrate;
adding a catalytic element to the amorphous semiconductor film;
heating the amorphous semiconductor film to form a crystalline semiconductor film;
forming a semiconductor region by etching the crystalline semiconductor film;
forming a barrier film covering the semiconductor region;
forming a heat retaining film over the barrier film so that the heat retaining film covers top surface and side surfaces of the semiconductor region through the barrier film;
after forming the heat retaining film, scanning a laser beam from one edge to another of the semiconductor region from the substrate side in order to improve crystalline characteristics of the semiconductor region;
after scanning the laser beam, removing the heat retaining film and the barrier film; and
after removing the heat retaining film, etching the semiconductor region in a manner that a scanning direction of the laser beam and a channel length direction of a thin film transistor are arranged in the same direction. - View Dependent Claims (12, 13, 14, 15, 16, 37, 43)
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17. A method for manufacturing a semiconductor device comprising:
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forming an amorphous semiconductor film comprising silicon over a substrate;
selectively adding a catalytic element to the amorphous semiconductor film;
heating the amorphous semiconductor film to form a crystalline semiconductor film, wherein the amorphous semiconductor film is crystallized in a direction parallel to the substrate from a region where the catalytic element was selectively added;
forming a semiconductor region by etching the crystalline semiconductor film;
forming a barrier film covering the semiconductor region;
forming a heat retaining film over the barrier film so that the heat retaining film covers top surface and side surfaces of the semiconductor region through the barrier film;
after forming the heat retaining film, scanning a laser beam from one edge to another of the semiconductor region from the substrate side in order to improve crystalline characteristics of the semiconductor region;
after scanning the laser beam, removing the heat retaining film and the barrier film; and
after removing the heat retaining film, etching the semiconductor region in a manner that a scanning direction of the laser beam and a channel length direction of a thin film transistor are arranged in the same direction. - View Dependent Claims (18, 19, 20, 21, 22, 38, 44)
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23. A method for manufacturing a semiconductor device comprising:
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forming a first amorphous semiconductor film over a substrate;
adding a catalytic element to the first amorphous semiconductor film;
heating the first amorphous semiconductor film to form a crystalline semiconductor film;
forming a seed crystal region by etching the crystalline semiconductor film;
forming a second amorphous semiconductor film comprising silicon over the substrate, overlapping with the seed crystal region, etching the second amorphous semiconductor film to form a semiconductor region overlapping with the seed crystal region at least partly;
forming a barrier film covering the semiconductor region;
forming a heat retaining film over the barrier film so that the heat retaining film covers top surface and side surfaces of the semiconductor region through the barrier film;
after forming the heat retaining film, crystallizing the semiconductor region by scanning a laser beam from one edge overlapping with the seed region to another of the semiconductor region from the substrate side;
after crystallizing the semiconductor region, removing the heat retaining film and the barrier film; and
after removing the heat retaining film, etching the semiconductor region and the seed crystal region in a manner that a scanning direction of the laser beam and a channel length direction of a thin film transistor are arranged in the same direction. - View Dependent Claims (24, 25, 26, 27, 28, 39, 45, 47)
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29. A method for manufacturing a semiconductor device comprising:
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forming a first amorphous semiconductor film containing silicon and germanium over a substrate, adding a catalytic element to the first amorphous semiconductor film;
heating the first amorphous semiconductor film to form a crystalline semiconductor film;
forming a seed crystal region by etching the crystalline semiconductor film;
forming a second amorphous semiconductor film comprising silicon over the substrate, overlapping with the seed crystal region;
etching the second amorphous semiconductor film to form a semiconductor region overlapping with the seed crystal region at least partly;
forming a barrier film covering the semiconductor region;
forming a heat retaining film over the barrier film so that the heat retaining film covers top surface and side surfaces of the semiconductor region through the barrier film;
after forming the heat retaining film, crystallizing the semiconductor region by scanning a laser beam from one edge to another of the semiconductor region through the substrate;
after crystallizing the semiconductor region, removing the retaining film and the barrier film; and
after removing the retaining film, etching the semiconductor region and the seed crystal region in a manner that a scanning direction of the laser beam and a channel length direction of a thin film transistor are arranged in the same direction. - View Dependent Claims (30, 31, 32, 33, 34, 40, 46, 48)
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Specification