SOI substrate and manufacturing method thereof

A method for manufacturing an SOI substrate, comprising the steps of:

• irradiating a semiconductor substrate with ions to form an embrittlement layer in the semiconductor substrate;
• bonding the semiconductor substrate to a base substrate;
• performing a first heat treatment on the semiconductor substrate at a first temperature;
• and,
• performing a second heat treatment on one region which is a part of the semiconductor substrate at a second temperature higher than the first temperature to form a semiconductor layer over the base substrate by causing separation at the embrittlement layer,
• wherein the separation proceeds from the one region of the semiconductor substrate to the other region of the semiconductor substrate.

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

• irradiating a semiconductor substrate with ions to form an embrittlement layer in the semiconductor substrate;
• bonding the semiconductor substrate to a base substrate;
• and,
• heating a first region of the semiconductor substrate at a first temperature and a second region of the semiconductor substrate at a second temperature lower than the first temperature to form a first semiconductor layer over the base substrate by causing separation at the embrittlement layer;
• removing a region of the first semiconductor layer corresponding to the first region of the semiconductor substrate to form a second semiconductor layer;
• and
• forming a semiconductor element with the second semiconductor layer,
• wherein the separation proceeds from the first region of the semiconductor substrate to the second region of the semiconductor substrate.

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

• irradiating a semiconductor substrate with ions to form an embrittlement layer in the semiconductor substrate;
• bonding the semiconductor substrate to a base substrate;
• performing a first heat treatment on the semiconductor substrate at a first temperature;
• performing a second heat treatment on one region which is a part of the semiconductor substrate at a second temperature higher than the first temperature to form a first semiconductor layer over the base substrate by causing separation at the embrittlement layer;
• removing a region of the first semiconductor layer corresponding to the one region of the semiconductor substrate to form a second semiconductor layer;
• and
• forming a semiconductor element with the second semiconductor layer,
• wherein the separation proceeds from the one region of the semiconductor substrate to the other region of the semiconductor substrate.