Semiconductor device and manufacturing method thereof

A method for manufacturing a semiconductor device including a semiconductor substrate, a field effect transistor provided on the semiconductor substrate and having a gate recess and a Schottky junction for a gate electrode, and a pn junction diode provided on the semiconductor substrate, the method comprising:

• a step of preparing the semiconductor substrate;
• a step of forming a channel layer for the field effect transistor, a first etching stopper layer, an n-type common layer used for contact layers for the field effect transistor and for an n-type layer for the diode, a second etching stopper layer, a p-type layer for the diode, and a third etching stopper layer on the semiconductor substrate in that order by epitaxial growth;
• an etching step of etching away the p-type layer and the third etching stopper layer in regions in which the field effect transistor and a cathode of the diode are to be formed so that the etching is to be stopped by the second etching stopper layer;
• a step of simultaneously forming a source electrode and a drain electrode for the field effect transistor and the cathode for the diode so as to have an ohmic contact with the n-type common layer;
• a step of forming a mask having openings which expose a region of the n-type common layer in which the gate recess for the field effect transistor is to be formed and at least a portion of the third etching stopper layer;
• a step of performing etching through the mask for forming the gate recess in the n-type common layer while the third etching stopper layer prevents the p-type layer from being etched, in which the etching is stopped by the first etching stopper layer;
• a step of simultaneously forming the gate electrode for the field effect transistor which has a Schottky contact with the channel layer and an anode for the diode which has an ohmic contact with the p-type layer through the mask;
• and
• a step of removing the mask.