Sharp Kabushiki Kaisha Corporation

Semiconductor Energy Laboratory Co., Ltd.

Takamasa Kousai

Hongyong Zhang

Akiharu Miyanaga

Naoki Makita

Toru Takayama

Yoshitaka Yamamoto

Tadayoshi Miyamoto

Masashi Maekawa

Takashi Funai

In a fabrication of a semiconductor device, an amorphous semiconductor film is first formed on a substrate having an insulating surface. Then, a minute amount of catalyst elements for accelerating crystallization of the amorphous semiconductor film is supplied to at least a portion of a surface of the amorphous semiconductor film. A heat treatment is further conducted so that the supplied catalyst elements are diffused into the amorphous semiconductor film. Thus, the catalyst elements are introduced uniformly into the amorphous semiconductor film in a very minute amount or at a low concentration, resulting in polycrystallization of at least a portion of the amorphous semiconductor film. Utilizing the thus obtained crystalline semiconductor film on the substrate surface as an active region, a semiconductor device such as a TFT is fabricated. The introduction of the catalyst elements are conducted by various methods such as: a formation of a film containing a minute amount of the catalyst elements; application of a solution containing the catalyst elements in several spin coating cycles; diffusion of the catalyst elements through a buffer layer; dipping into a solution in which the catalyst elements are dissolved or dispersed; or formation of a plating layer containing the catalyst elements.

Method for fabricating thin film transistors

A method of fabricating a semiconductor device by the use of laser crystallization steps is provided. During these crystallization steps, an amorphous or polycrystalline semiconductor is crystallized by laser irradiation in such a way that generation of ridges is suppressed. Two separate laser crystallization steps are carried out. First, a laser irradiation step is performed in a vacuum, using somewhat weak laser light. Then, another laser irradiation step is performed in a vacuum, in the atmosphere, or in an oxygen ambient with intenser laser light. The first laser irradiation conducted in a vacuum does not result in satisfactory crystallization. However, this irradiation can suppress generation of ridges. The second laser irradiation step is performed in a vacuum, in the atmosphere, or in an oxygen ambient to achieve sufficient crystallization, but no ridges are produced.

Method of processing semiconductor device with laser

A liquid crystal display device including: a display section including a liquid crystal layer; a pair of substrates interposing the liquid crystal layer; a plurality of pixel electrodes located in a matrix on one of the pair of substrates; a plurality of first thin film transistors respectively connected to the plurality of pixel electrodes; and a peripheral driving circuit located for driving the display section, the peripheral driving circuit being located on the substrate on which the first thin film transistors are located and having a second thin film transistor. Each of the first thin film transistors includes a first channel layer formed of a first crystalline silicon layer, and the second thin film transistor includes a second channel layer formed of a second crystalline silicon layer having a higher mobility than the mobility of the first crystalline silicon layer. The second crystalline silicon layer includes a catalytic element for promoting crystallization.

Semiconductor device method for producing the same and liquid crystal

Growing community of inventors

Ohsaka, Japan

Takamasa Kousai