Oxide sintered material, method of producing oxide sintered material, sputtering target, and method of producing semiconductor device

1. An oxide sintered material containing indium, tungsten, and zinc, the oxide sintered material comprising:

a first crystal phase that is a main component of the oxide sintered material and includes a bixbyite type crystal phase; and

a second crystal phase having a content of the zinc higher than a content of the zinc in the first crystal phase,

the second crystal phase including particles having an average major axis size of not less than 3 μm and not more than 50 μm and having an average aspect ratio of not less than 4 and not more than 50.

2. The oxide sintered material according to claim 1 , wherein

the oxide sintered material has a first diffraction peak at a location of more than 34.74 deg and less than 34.97 deg of 2θ in X-ray diffraction, and has a second diffraction peak at a location of more than 31.77 deg and less than 32.00 deg of 2θ, and

a ratio Ia/Ib of a peak intensity Ia of the first diffraction peak to a peak intensity Ib of the second diffraction peak is not less than 0.05 and not more than 3.

3. The oxide sintered material according to claim 1 , wherein

the oxide sintered material has an apparent density of more than 6.4 g/cm 3 and not more than 7.5 g/cm 3 ,

a content of the tungsten relative to a total of the indium, the tungsten, and the zinc in the oxide sintered material is more than 0.5 atom % and not more than 5.0 atom %,

a content of the zinc relative to the total of the indium, the tungsten, and the zinc in the oxide sintered material is not less than 1.2 atom % and less than 50 atom %, and

an atomic ratio of the zinc to the tungsten in the oxide sintered material is more than 1.0 and less than 100.

4. A sputtering target comprising the oxide sintered material recited in claim 1 .