Manufacturing method for semiconductor device

A manufacturing method for a semiconductor device comprising:

• preparing a semiconductor substrate of a first conduction type having a first principal plane and a second principal plane opposed to the first principal plane and having carbon and oxygen;
• forming a first semiconductor layer of a second conduction type having impurity concentration higher than impurity concentration of the semiconductor substrate on the first principal plane side of the semiconductor substrate;
• after forming the first semiconductor layer, grinding the semiconductor substrate from the second principal plane side;
• after grinding the semiconductor substrate, forming a second semiconductor layer of the first conduction type or the second conduction type having impurity concentration higher than impurity concentration of the semiconductor substrate on the second principal plane side of the semiconductor substrate;
• after grinding the semiconductor substrate, injecting protons from the second principal plane side;
• a first heat treatment step of heating the semiconductor substrate at a first temperature, converting the protons injected into the semiconductor substrate into hydrogen-induced donors, and forming a first buffer layer of the first conduction type having impurity concentration higher than the impurity concentration of the semiconductor substrate;
• after the first heat treatment step, a charged particle irradiating step of irradiating the semiconductor substrate with charged particles and forming a complex defect of interstice carbon and interstice oxygen and a complex defect of interstice carbon and lattice position carbon;
• and
• after the charged particle irradiating step, a second heat treatment step of heating the semiconductor substrate at a second temperature lower than the first temperature and extinguishing the complex defect of interstice carbon and lattice position carbon.