| 摘要 |
PROBLEM TO BE SOLVED: To reduce the size of an upper electrode for a via hole and to reduce chip area. SOLUTION: An insulation film 32 is deposited on a GaAs substrate 31, and an upper electrode 33 is formed on the insulation film 32. A through-hole 31a and a through-hole 31b are formed in the GaAs substrate 31. The through- hole 31a is formed by the same method as a prior method. On the other hand, after the formation of the through-hole 31a, the through-hole 31b is formed by stain etching a portion including n-type or p-type impurities selectively diffused from the surface. Therefore, if the pattern of the isolation film 32, which is opened by the diffusion of n-type or p-type impurities, is small, the diameter of the through-hole 31b can be sufficiently smaller than the diameter of the through-hole 31a. As a result, the upper electrode 33 for the via hole also becomes smaller.
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