Semiconductor Energy Laboratory Co., Ltd.

Hideyuki Kishida

Shunpei Yamazaki

Junichiro Sakata

Akiharu Miyanaga

Masahiro Takahashi

Takuya Hirohashi

Masayuki Sakakura

Kengo Akimoto

Toshikazu Kondo

Jun Koyama

Hideki Uochi

Yasuo Nakamura

Junpei Sugao

Ryosuke Watanabe

Kenichi Okazaki

Masashi Tsubuku

Yusuke Nonaka

Motoki Nakashima

Masashi Oota

Noritaka Ishihara

Mitsuo Mashiyama

Masahiro Watanabe

Hiromichi Godo

Junichi Koezuka

Yuichi Sato

Shinji Ohno

Toshinari Sasaki

Hiroki Ohara

The impurity concentration in the oxide semiconductor film is reduced, and a highly reliability can be obtained.

Method for forming oxide semiconductor film, semiconductor device, and method for manufacturing semiconductor device

In a thin film transistor, an increase in off current or negative shift of the threshold voltage is prevented. In the thin film transistor, a buffer layer is provided between an oxide semiconductor layer and each of a source electrode layer and a drain electrode layer. The buffer layer includes a metal oxide layer which is an insulator or a semiconductor over a middle portion of the oxide semiconductor layer. The metal oxide layer functions as a protective layer for suppressing incorporation of impurities into the oxide semiconductor layer. Therefore, in the thin film transistor, an increase in off current or negative shift of the threshold voltage can be prevented.

Thin film transistor, method for manufacturing the same, and semiconductor device

It is an object to provide a highly reliable semiconductor device including a thin film transistor with stable electric characteristics. In a semiconductor device including an inverted staggered thin film transistor whose semiconductor layer is an oxide semiconductor layer, a buffer layer is provided over the oxide semiconductor layer. The buffer layer is in contact with a channel formation region of the semiconductor layer and source and drain electrode layers. A film of the buffer layer has resistance distribution. A region provided over the channel formation region of the semiconductor layer has lower electrical conductivity than the channel formation region of the semiconductor layer, and a region in contact with the source and drain electrode layers has higher electrical conductivity than the channel formation region of the semiconductor layer.

Semiconductor device and method for manufacturing the same

By using a conductive layer including Cu as a long lead wiring, increase in wiring resistance is suppressed. Further, the conductive layer including Cu is provided in such a manner that it does not overlap with the oxide semiconductor layer in which a channel region of a TFT is formed, and is surrounded by insulating layers including silicon nitride, whereby diffusion of Cu can be prevented; thus, a highly reliable semiconductor device can be manufactured. Specifically, a display device which is one embodiment of a semiconductor device can have high display quality and operate stably even when the size or definition thereof is increased.

An object is to provide a semiconductor device including an oxide semiconductor with stable electric characteristics can be provided. An insulating layer having many defects typified by dangling bonds is formed over an oxide semiconductor layer with an oxygen-excess mixed region or an oxygen-excess oxide insulating layer interposed therebetween, whereby impurities in the oxide semiconductor layer, such as hydrogen or moisture (a hydrogen atom or a compound including a hydrogen atom such as HO), are moved through the oxygen-excess mixed region or oxygen-excess oxide insulating layer and diffused into the insulating layer. Thus, the impurity concentration of the oxide semiconductor layer is reduced.

Semiconductor device having a first region comprising silicon, oxygen and at least one metal element formed between an oxide semiconductor layer and an insulating layer

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Atsugi, Japan

Hideyuki Kishida