| 摘要 |
PURPOSE:To form a very small gate electrode by etching away the coating of a region in which the gate electrode is to be formed by means of an ion beam, and forming a resist pattern having a 'T'-shaped cross section utilizing the difference of the range into the ion beam in the removed portion and the portion which is not removed. CONSTITUTION:A resist 2 is applied on a substrate 1, and a silicon film 3 is formed thereon. Then, when a portion in which a gate electrode is to be formed is irradiated with an ion beam 4a of 1X10<16>/cm<2>, the silicon film 3 is etched away, and the resist 2 therebelow is exposed as far as the substrate surface under the resist 2 to a radiation of about 1X10<13>/cm<2> and becomes an exposed portion 5a. Then, the peripheral portion of the exposed portion 5a is irradiated with an ion beam 4b of 1X10<14>/cm<2> to form an exposed portion 5b. Since the silicon film 3 is not etched by such a dose of irradiation, the ion beam 4b irradiated through the silicon film 3 does not reach the semiconductor substrate 1, forming a resist exposed portion 5 having a structure with a 'T'-shaped cross section.
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