Thin film semiconductor device containing polycrystalline Si—Ge alloy and method for producing thereof
First Claim
1. A method for producing a thin film transistor device comprising steps of:
- (a) forming an amorphous Si1-xGex layer of a film thickness of 10-100 nm on an insulator substrate in which a Ge concentration x is 0<
x<
1; and
(b) being subjected to a heat treatment for crystallizing the amorphous Si1-xGex layer by an excimer laser with an energy density of 200-300 mJ/cm2 and the pulse number of 1-50 by which the amorphous Si1-xGex layer turns to a silicone-germanium poly-crystalline Si1-xGex in which a Ge concentration x is 0<
x<
1, and a Ge concentration x in the poly-crystalline thin film is larger in a grain boundary than a portion where a Ge concentration in an interior crystal grain of the poly-crystalline thin film becomes a minimum value.
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Accused Products
Abstract
The present invention relates to a thin film transistor, in a low-temperature poly-Si thin film becoming an elemental material of the thin film transistor, an object of the invention is to provide the thin film transistor suitable for realizing an image display device having a high performance and a large area at low cost by realizing a poly-crystalline thin film having a crystal structure restraining current scattering in a grain boundary, lessening surface roughness, and capable of realizing high mobility even to a positive hole current.
The object described above is achieved by realizing a TFT with high mobility by restraining a current scattering factor in a grain boundary of crystal with an introduction of Ge into the poly-crystalline Si thin film and with a difference in ratios of Ge compositions between an interior grain of crystal and a grain boundary of crystal resulted from a phase separation involved in crystallization, and by restraining surface roughness using a difference in volumes in a crystal.
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Citations
8 Claims
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1. A method for producing a thin film transistor device comprising steps of:
-
(a) forming an amorphous Si1-xGex layer of a film thickness of 10-100 nm on an insulator substrate in which a Ge concentration x is 0<
x<
1; and
(b) being subjected to a heat treatment for crystallizing the amorphous Si1-xGex layer by an excimer laser with an energy density of 200-300 mJ/cm2 and the pulse number of 1-50 by which the amorphous Si1-xGex layer turns to a silicone-germanium poly-crystalline Si1-xGex in which a Ge concentration x is 0<
x<
1, and a Ge concentration x in the poly-crystalline thin film is larger in a grain boundary than a portion where a Ge concentration in an interior crystal grain of the poly-crystalline thin film becomes a minimum value.- View Dependent Claims (2, 3, 4)
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5. A method of forming a transistor device comprising:
-
(a) forming an amorphous Si1-xGex layer having a thickness of 10-100 nm on an insulator substrate in which a Ge concentration x is 0<
x<
1; and
(b) heat treating the amorphous Si1-xGex layer using an excimer laser with an energy density of 200-300 mJ/cm2 and a pulse number of 1-50 by which the amorphous Si1-xGex layer turns to a silicone-germanium poly-crystalline Si1-xGex in which a Ge concentration x is 0<
x<
1, and a Ge concentration x in the poly-crystalline thin film is larger in a grain boundary than a portion where a Ge concentration in an interior crystal grain of the poly-crystalline thin film becomes a minimum value.- View Dependent Claims (6, 7, 8)
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Specification