Semiconductor device and method of manufacturing semiconductor device

A method of manufacturing a semiconductor device, comprising:

• forming a first semiconductor region of a second conduction type on a side of a wafer of a first conduction type;
• forming a front surface element structure on a first main surface of the wafer;
• forming a concave portion extending from a second main surface of the wafer to the first semiconductor region;
• forming a second semiconductor region of the second conduction type so as to be electrically connected to the first semiconductor region, the second main surface of the wafer being disposed on the second semiconductor region;
• and
• removing a portion of the first semiconductor region and cutting the wafer into chips,
• the removing being performed so that the first semiconductor region is removed such that a cut plane of the first semiconductor region is inclined with respect to the first main surface of the wafer.

A method of manufacturing a semiconductor device, comprising:

• patterning a resist applied onto a surface of a wafer to form a mask in which a region where a concave portion of the wafer to be formed is exposed;
• and
• performing etching with an alkali etchant using the mask to form the concave portion in the wafer,
• wherein a corner of the mask includes a protruding portion that protrudes onto the region in which the concave portion is formed.