FIGS. 17A and 17B respectively are a typical cross sectional view and an equivalent circuit diagram of a Schottky TTL. Referring to FIGS. 17A and 17B, reference numeral 2201 represents a silicon substrate, 2202 represents a collector of a bipolar transistor, 2203 represents a base of the bipolar transistor, 2204 represents an emitter of the bipolar transistor, 2205 represents an aluminum layer con