| 摘要 |
PROBLEM TO BE SOLVED: To solve such a problem that a semiconductor wafer is curved when a nitride semiconductor area is provided on a silicon substrate. SOLUTION: A main semiconductor area 4 made of nitride semiconductor for HEMT is provided on a silicon substrate 2 with a buffer area 3 made of nitride semiconductor in between. The buffer area 4 is comprised of a first multilayer buffer area 5 and a second multilayer buffer area 8. The first multilayer buffer area 5 is comprised of a plurality of sub-multilayer buffer areas 6 and a plurality of single-layered buffer areas 7. The sub-multilayer buffer areas 6 are comprised of a plurality of first and second layers that are alternatively arranged. The first layer is formed of nitride semiconductor containing aluminum at a first ratio. The second layer is formed of nitride semiconductor containing no aluminum or containing aluminum at a smaller ratio than the first ratio. The second multilayer buffer area 8 is comprised of third and fourth layers. The ratio of aluminum included in the third layer is made smaller than that in the first layer. COPYRIGHT: (C)2008,JPO&INPIT
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