Abstract: Between a back surface electrode and an electrode, a first thyristor is formed of fifth and seventh semiconductor regions, a substrate region, first and second semiconductor regions and a third semiconductor region, and a second thyristor is formed of the second and first semiconductor regions, the substrate region, the seventh and fifth semiconductor regions and a sixth semiconductor region. Depths from the surface of the semiconductor substrate to bottom surfaces of the third and fourth semiconductor regions are 20 ?m or more. The second semiconductor region with a high impurity concentration is enclosed by the first semiconductor region with a low impurity concentration, and a difference between a depth from the surface of the semiconductor substrate to the bottom of the second semiconductor region and a depth from the surface of the semiconductor substrate to the bottom of the first semiconductor region is less than 10 ?m.

Abstract: Between a back surface electrode and an electrode, a first thyristor is formed of fifth and seventh semiconductor regions, a substrate region, first and second semiconductor regions and a third semiconductor region, and a second thyristor is formed of the second and first semiconductor regions, the substrate region, the seventh and fifth semiconductor regions and a sixth semiconductor region. Depths from the surface of the semiconductor substrate to bottom surfaces of the third and fourth semiconductor regions are 20 ?m or more. The second semiconductor region with a high impurity concentration is enclosed by the first semiconductor region with a low impurity concentration, and a difference between a depth from the surface of the semiconductor substrate to the bottom of the second semiconductor region and a depth from the surface of the semiconductor substrate to the bottom of the first semiconductor region is less than 10 ?m.

Abstract: The present invention improves the performance of a semiconductor device formed with a triac. A thyristor is formed between a back surface electrode and an electrode by p-type semiconductor regions, an n-type substrate region, p-type semiconductor regions and an n-type semiconductor region. A thyristor is formed therebetween by the p-type semiconductor regions, the n-type substrate region, the p-type semiconductor regions and an n-type semiconductor region. The two thyristors are opposite in the direction of currents flowing between the back surface electrode and the electrode. The p-type semiconductor region of a high impurity concentration is formed so as to be internally included in the p-type semiconductor region of a low impurity concentration. The p-type semiconductor region of a low impurity concentration is interposed between the p-type semiconductor region of a high impurity concentration and the n-type substrate region.

Abstract: The present invention improves the performance of a semiconductor device formed with a triac. A thyristor is formed between a back surface electrode and an electrode by p-type semiconductor regions, an n-type substrate region, p-type semiconductor regions and an n-type semiconductor region. A thyristor is formed therebetween by the p-type semiconductor regions, the n-type substrate region, the p-type semiconductor regions and an n-type semiconductor region. The two thyristors are opposite in the direction of currents flowing between the back surface electrode and the electrode. The p-type semiconductor region of a high impurity concentration is formed so as to be internally included in the p-type semiconductor region of a low impurity concentration. The p-type semiconductor region of a low impurity concentration is interposed between the p-type semiconductor region of a high impurity concentration and the n-type substrate region.