Oxide sintered body, sputtering target, and oxide semiconductor thin film obtained using sputtering target

Abstract

Provided are: a sintered oxide which achieves low carrier density and high carrier mobility when configured as an oxide semiconductor thin-film by using the sputtering method; and a sputtering target using the same. This sintered oxide contains indium, gallium and magnesium as oxides. It is preferable for the gallium content to be at least 0.08 and less than 0.20, inclusive, in terms of an atomic ratio (Ga / (In+Ga)), the magnesium content to be at least 0.0001 and less than 0.05 in terms of an atomic ratio (Mg / (In+Ga+Mg)), and the sintering to occur at 1,200-1,550° C., inclusive. An amorphous oxide semiconductor thin-film obtained by forming this sintered oxide as a sputtering target is capable of achieving a carrier density of less than 1.0×1018 cm−3, and a carrier mobility of 10 cm2 V−1 sec−1 or higher.

Description

TECHNICAL FIELD[0001]The present invention relates to an oxide sintered body, a target, and an oxide semiconductor thin film obtained by using the target, and more particularly to a crystalline oxide semiconductor thin film which has low carrier density and high carrier mobility and contains indium, gallium, and magnesium, a sputtering target that is suitable for the formation of the crystalline oxide semiconductor thin film and contains indium, gallium, and magnesium, and an oxide sintered body that is suitable for obtaining the sputtering target and contains indium, gallium, and magnesium.BACKGROUND ART[0002]Thin film transistors (TFTs) are a type of field effect transistors (hereinafter referred to as FETs). TFTs are three-terminal elements having a gate terminal, a source terminal, and a drain terminal in the basic structure. TFTs are active elements having a function of switching the current between the source terminal and the drain terminal so that a semiconductor thin film de...

AI Technical Summary

Benefits of technology

The present invention is related to an oxide sintered body, which can be used as a target for sputter deposition to produce a crystalline oxide semiconductor thin film. This thin film has a bixbyite structure and a predetermined amount of magnesium, which helps to reduce carrier density. Therefore, this thin film is useful in TFTs as it increases the on / off ratio. The oxide sintered body is composed of two phases, which enhances carrier mobility. This invention is useful in the industrial production of a high-quality oxide semiconductor thin film.

Problems solved by technology

MIS-FETs including silicon are opaque to visible light and thus fail to form transparent circuits.

However, oxygen defects are likely to be generated in the amorphous oxide thin film, and electron carriers do not always stably behave in response to external factors such as heat.

It has been pointed out that these facts often have adverse effects and cause problems associated with instability of devices, such as TFTs, when the devices are formed.

However, there is still a problem in that the carrier density described in Examples 1 to 8 in Patent Document 2 is of the order of 1018 cm−3, which is too high for an oxide semiconductor thin film to be used in TFTs.

However, the target disclosed in Patent Document 3 includes a phase such as Ga2MgO4, which has low conductivity so as to cause arcing, and thus there is a problem that abnormal discharge is caused.