Semiconductor device and method of manufacturing the same

A method at manufacturing a semiconductor device, comprising the steps of:

• (a) forming a plurality of first grooves over a semiconductor layer of a first conductivity type;
• (b) forming a first semiconductor region of a second conductivity type on a side of each first groove by implanting an impurity of the second conductivity type opposite to the first conductivity type to the side of the first groove diagonally at a first angle with respect to a top surface of the semiconductor laver;
• (c) forming a first pillar in each first groove by filling the first groove with a semiconductor of the second conductivity type, and forming a second pillar including the semiconductor layer between the first pillars;
• and
• (d) forming a semiconductor element over the semiconductor layer,
• wherein the first semiconductor region is formed from an upper end of a side of the second pillar to a certain depth of the second pillar,
• wherein the method further comprises the step of:
• (b2) after the step (a), forming a second semiconductor region of the second conductivity type over the side of the first groove by implanting the impurity of the second conductivity type to the side of the first groove diagonally at a second angle with respect to the top surface of the semiconductor layer before the step (c),
• wherein the first angle is closer to a right angle with respect to the top surface of the semiconductor layer than the second angle,
• wherein the second semiconductor region has a smaller depth than the first semiconductor region, and
• wherein the second semiconductor region has a larger width than the first semiconductor region in a first direction along which the first and second pillars are arranged.