Semiconductor device
First Claim
1. A method for forming a semiconductor device comprising the steps of:
- forming a gate electrode;
forming a gate insulating film over the gate electrode;
forming an oxide semiconductor film comprising a channel formation region over the gate insulating film;
forming a metal oxide film over and in contact with the oxide semiconductor film;
performing a heat treatment after forming the metal oxide film;
forming a source electrode and a drain electrode over the metal oxide film, the source electrode and the drain electrode being in contact with the oxide semiconductor film; and
forming an electrode over the metal oxide film and overlapping with the gate electrode,wherein the oxide semiconductor film contains one or more metal elements,wherein the metal oxide film contains at least one of the metal elements contained in the oxide semiconductor film, andwherein a side surface of the oxide semiconductor film is in contact with the metal oxide film.
1 Assignment
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Accused Products
Abstract
An object is to provide a semiconductor device using an oxide semiconductor having stable electric characteristics and high reliability. A transistor including the oxide semiconductor film in which a top surface portion of the oxide semiconductor film is provided with a metal oxide film containing a constituent similar to that of the oxide semiconductor film and functioning as a channel protective film is provided. In addition, the oxide semiconductor film used for an active layer of the transistor is an oxide semiconductor film highly purified to be electrically i-type (intrinsic) by heat treatment in which impurities such as hydrogen, moisture, a hydroxyl group, or a hydride are removed from the oxide semiconductor and oxygen which is a major constituent of the oxide semiconductor and is reduced concurrently with a step of removing impurities is supplied.
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Citations
19 Claims
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1. A method for forming a semiconductor device comprising the steps of:
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forming a gate electrode; forming a gate insulating film over the gate electrode; forming an oxide semiconductor film comprising a channel formation region over the gate insulating film; forming a metal oxide film over and in contact with the oxide semiconductor film; performing a heat treatment after forming the metal oxide film; forming a source electrode and a drain electrode over the metal oxide film, the source electrode and the drain electrode being in contact with the oxide semiconductor film; and forming an electrode over the metal oxide film and overlapping with the gate electrode, wherein the oxide semiconductor film contains one or more metal elements, wherein the metal oxide film contains at least one of the metal elements contained in the oxide semiconductor film, and wherein a side surface of the oxide semiconductor film is in contact with the metal oxide film. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A method for forming a semiconductor device comprising the steps of:
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forming an oxide semiconductor film comprising a channel formation region; forming a metal oxide film over and in contact with the oxide semiconductor film; performing a heat treatment after forming the metal oxide film; forming a source electrode and a drain electrode over the metal oxide film, the source electrode and the drain electrode being in contact with the oxide semiconductor film; and forming an electrode over the metal oxide film, wherein the electrode overlaps with the channel formation region with the metal oxide film interposed therebetween, wherein the oxide semiconductor film contains one or more metal elements, wherein the metal oxide film contains at least one of the metal elements contained in the oxide semiconductor film, and wherein a side surface of the oxide semiconductor film is in contact with the metal oxide film. - View Dependent Claims (8, 9, 10, 11, 12)
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13. A method for forming a semiconductor device comprising the steps of:
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forming a gate electrode; forming a gate insulating film over the gate electrode; forming a first metal oxide film over the gate insulating film; forming an oxide semiconductor film comprising a channel formation region over the first metal oxide film; forming a second metal oxide film over and in contact with the oxide semiconductor film; performing a heat treatment after forming the second metal oxide film; and forming a source electrode and a drain electrode over the second metal oxide film, the source electrode and the drain electrode being in contact with the oxide semiconductor film, wherein the oxide semiconductor film contains one or more metal elements, wherein each of the first metal oxide film and the second metal oxide film contains at least one of the metal elements contained in the oxide semiconductor film, and wherein a side surface of the oxide semiconductor film is in contact with the second metal oxide film. - View Dependent Claims (14, 15, 16, 17, 18, 19)
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Specification