Semiconductor substrate, substrate for semiconductor crystal growth, semiconductor device, optical semiconductor device, and manufacturing method thereof

A manufacturing method of a semiconductor substrate including the steps of:

• growing a semiconductor crystal layer on one face of a substrate;
• and
• forming a stress relaxation layer on the other face of the substrate opposite to said one face and on a side face of the substrate continuously from the other face of the substrate, the stress relaxation layer applying stress to the substrate in the same direction as the direction of stress which the semiconductor crystal layer applies to the substrate.

A substrate for semiconductor crystal growth comprising:

• a stress relaxation layer that is formed on an other face opposite to one face of the substrate and is formed on a side face of the substrate continuously from the other face of the substrate, the stress relaxation layer applying stress to the substrate for a semiconductor crystal layer in the same direction as the direction of stress from the semiconductor crystal layer formed on the other one face of the substrate.

A manufacturing method of a substrate for semiconductor crystal growth comprising the step of:

• forming a stress relaxation layer that is formed on an other face opposite to one face of the substrate and is formed on a side face of the substrate continuously from the other face of the substrate, the stress relaxation layer applying stress to the substrate for a semiconductor crystal layer in the same direction as the direction of stress from the semiconductor crystal layer formed on the one face of the substrate.

A semiconductor device comprising:

• a semiconductor crystal layer, which is provided on one face of a substrate and becomes an operating layer of a field effect transistor;
• and
• a stress relaxation layer, which is provided on the other face of the substrate opposite to said one face divided into a chip and is provided on the side face of the substrate continuously from the other face of the substrate, and which applies stress to the substrate in the same direction as the direction of stress which the semiconductor crystal layer applies to the substrate.

A manufacturing method of a semiconductor device including the step of:

• forming a stress relaxation layer, which applies stress to a substrate in the same direction as the direction of stress which a semiconductor crystal layer applies to the substrate, on the other face of the substrate opposite to one face thereof and on a region defining a side face when the substrate is divided into chips, the other face of the substrate being provided with the semiconductor crystal layer to become an operating layer of a field effect transistor.

An optical semiconductor device comprising:

• a semiconductor crystal layer, which is provided on one face of a substrate and includes an active layer and cladding layers sandwiching the active layer in between;
• and
• a stress relaxation layer, which is provided on the other face of the substrate divided into a chip and is provided on the side face of the substrate continuously from the other face of the substrate opposite to said one face, and applies stress to the substrate in the same direction as the direction of stress which the semiconductor crystal layer applies to the substrate.

A manufacturing method of an optical semiconductor device including the step of:

• forming a stress relaxation layer, which applies stress to a substrate in the same direction as the direction of stress which a semiconductor crystal layer applies to the substrate, on the other face of the substrate and the other face of the semiconductor is provided with an active layer and cladding layers where the active layer is placed between the cladding layers in a vertical direction and on a region defining a side face when the substrate is divided into chips.