| 摘要 |
PURPOSE:To make it possible to form cavities from simple forms to complicated forms, by using a material, which is removed with sublimation or decomposition by heating. CONSTITUTION:An insulating film 2, which is to become a spacer, is formed on a silicon substrate 1. The insulating film on a gate region is etched. The outer surface of poly-alpha-methylstyrene 3 is surrounded with the insulating film 2 of the spacer on the silicon wafer 1. The thickness of the poly-alpha-methylstyrene 3 and the thickness of the insulating film 2 are made equal in this structure. Then, a film (diaphragm) 4 made of aluminum, nickel or SiO2 is formed on the said film. Thereafter, a small hole 5 reaching the end part of the patterned poly-alpha-methylstyrene 3 is provided in the rear surface of the silicon wafer 1 by etching. Finally heat treatment is performed in a vacuum state. Thus the poly-alpha-methylstyrene 3 is decomposed and removed through the small hole, and a minute cavity 6 is formed on an FET.
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