Semiconductor substrate, method for manufacturing semiconductor substrate and method for manufacturing semiconductor device

A method for manufacturing a semiconductor substrate comprising the steps of:

• preparing a base substrate;
• forming a first removal layer composed of AlxGa1-xAs (0.6<x≤0.8) on the base substrate;
• forming a second removal layer, above the first removal layer, that is composed of AlyGa1-yAs (0.7<y≤1, y>x) and has a larger etching rate for a predetermined etching material than the etching rate of the first removal layer for the predetermined etching material;
• forming a semiconductor epitaxial layer composed of AltGa1-tAs (0≤t≤1) above the second removal layer;
• removing the second removal layer by performing etching using the predetermined etching material;
• and
• bonding the semiconductor epitaxial layer to a destination substrate different from the base substrate after removing the second removal layer.

A method for manufacturing a semiconductor device comprising the steps of:

• preparing a semiconductor substrate including a base substrate, a first removal layer that is provided on the base substrate and composed of AlxGa1-xAs (0.6<x≤0.8), a second removal layer that is provided above the first removal layer and is composed of AlyGa1-yAs (0.7<y≤1, y>x), and a semiconductor epitaxial layer that is provided above the second removal layer and composed of AltGa1-tAs (0≤t≤1), and the semiconductor substrate having a larger etching rate of the second removal layer for a predetermined etching material than the etching rate of the first removal layer for the predetermined etching material;
• removing the second removal layer by performing etching using the predetermined etching material;
• and
• bonding the semiconductor epitaxial layer to a destination substrate different from the base substrate after removing the second removal layer.