| 摘要 |
PROBLEM TO BE SOLVED: To improve reliability of element by prohibiting occurrence of cracks in an element itself, improving yield of element and eliminating residual stress of the element. SOLUTION: A plurality of cross grooves 31 are arranged on a sapphire substrate 11 in such a manner that the respective tips face the tip of other cross, and the point of each cross is positioned at the apex of square shapes. If a semiconductor layer of 3 to 5 group compounds is crystal-grown on the sapphire substrate 11, the crystal growth progresses along the groove of the cross groove 31. In this case, the portion surrounded by the slopes forming the groove effectively has a higher growth speed, and the growth plane is formed almost to a flat shape, so that stress tend to concentrate in this groove portion, cracks 33 outer along the side of the square shape described above but, instead, no crack occurs in the element region 32 inside the square shape. Because of this, no cracks 33 occur in the element itself so that not only the yield of the element can be improved but also the residual stresses of the element itself are eliminated and reliability of the element can be improved. |
