Semiconductor element and method of manufacturing the same

A semiconductor element, comprising:

• a first semiconductor layer of a first conduction type;
• a pillar layer including first semiconductor pillars of the first conduction type and second semiconductor pillars of a second conduction type arranged periodically and alternately on said first semiconductor layer;
• a first main electrode electrically connected to said first semiconductor layer;
• a semiconductor base layer of the second conduction type formed on the upper surface of said pillar layer;
• a second semiconductor layer of the first conduction type formed on the upper surface of said semiconductor base layer;
• a second main electrode electrically connected to said second semiconductor layer and said semiconductor base layer;
• and
• a control electrode of the trench gate type formed in a trench, said trench formed in depth through said semiconductor base layer to said first semiconductor pillar,
• wherein said control electrode is tapered such that the width thereof decreases with the distance from said second main electrode toward said first main electrode and the tip thereof locates almost at the center of said first semiconductor pillar.