Method for manufacturing semiconductor device
First Claim
1. A semiconductor device comprising:
- an oxide semiconductor film over a substrate;
a pair of buffer layers on the oxide semiconductor film;
a pair of electrodes electrically connected to the oxide semiconductor film;
a gate insulating film over and in contact with a portion of a top surface of the oxide semiconductor film, a top surface of the pair of electrodes and a side surface of the pair of buffer layers; and
a gate electrode over the gate insulating film,wherein each of the pair of buffer layers has a different taper angle between an inner side surface and an outer side surface, andwherein the buffer layers comprise a metal oxide.
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Abstract
An object is to manufacture a semiconductor device including an oxide semiconductor film, which has stable electric characteristics and high reliability. A crystalline oxide semiconductor film is formed, without performing a plurality of steps, as follows: by utilizing a difference in atomic weight of plural kinds of atoms included in an oxide semiconductor target, zinc with low atomic weight is preferentially deposited on an oxide insulating film to form a seed crystal including zinc; and tin, indium, or the like with high atomic weight is deposited on the seed crystal while causing crystal growth. Further, a crystalline oxide semiconductor film is formed by causing crystal growth using a seed crystal with a hexagonal crystal structure including zinc as a nucleus, whereby a single crystal oxide semiconductor film or a substantially single crystal oxide semiconductor film is formed.
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Citations
14 Claims
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1. A semiconductor device comprising:
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an oxide semiconductor film over a substrate; a pair of buffer layers on the oxide semiconductor film; a pair of electrodes electrically connected to the oxide semiconductor film; a gate insulating film over and in contact with a portion of a top surface of the oxide semiconductor film, a top surface of the pair of electrodes and a side surface of the pair of buffer layers; and a gate electrode over the gate insulating film, wherein each of the pair of buffer layers has a different taper angle between an inner side surface and an outer side surface, and wherein the buffer layers comprise a metal oxide. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A semiconductor device comprising:
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an oxide semiconductor film over a substrate; a pair of buffer layers having n-type conductivity on the oxide semiconductor film; a pair of electrodes electrically connected to the oxide semiconductor film; a gate insulating film over and in contact with a portion of a top surface of the oxide semiconductor film, a top surface of the pair of electrodes and a side surface of the pair of buffer layers; and a gate electrode over the gate insulating film, wherein each of the pair of buffer layers has a different taper angle between an inner side surface and an outer side surface. - View Dependent Claims (9, 10, 11, 12, 13, 14)
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Specification