Compound semiconductor device and method for manufacturing the same

A method for manufacturing a compound semiconductor device, the method comprising:

• providing a semiconductor substrate that includes a foundation layer having a first conductivity type and formed of a compound semiconductor;
• forming a deep trench in the foundation layer;
• and
• forming a deep layer that has a second conductivity type by introducing material gas of the compound semiconductor while introducing dopant gas including a second conductivity type dopant into an epitaxial growth equipment and causing epitaxial growth of the deep layer in the deep trench, wherein
• a period in which a temperature in the epitaxial growth equipment is increased to a temperature of the epitaxial growth of the deep layer is defined as a temperature increasing period, and
• in the forming the deep layer, the deep layer is further formed in a bottom corner portion of the deep trench by:
• starting the introducing of the dopant gas including the second conductivity type dopant during the temperature increasing period;
• and
• starting the introducing of the material gas during the temperature increasing period after the introducing of the second conductivity type dopant gas.

A compound semiconductor device comprising:

• a semiconductor substrate that includes a foundation layer having a first conductivity type and formed of a compound semiconductor;
• and
• a deep layer that has a second conductivity type and is disposed in a deep trench provided in the foundation layer,
• wherein
• the deep layer includes a high impurity concentration region disposed at a bottom corner portion of the deep trench, the high impurity concentration region has a second conductivity type impurity concentration higher than another region in the deep layer, and the high impurity concentration region has a cross-section shape of triangular shape or triangular round shape.