A Schottky-bartier diode with self-aligned floating guard ring is described. The device structure requires no additional mask or process step in an advanced bipolar LSI technology featuring polysilicon base contact and self-aligned emitter region . In contrast to conventional guard ring structures, the guard ring is separated from the anode by a sidewall oxide of thickness less than 0.3μm, allowing independent access to the guard ring. Near-ideal I-V characteristics are obtained. It is shown that the guard ring can be left floating ‘without degrading the I-V characteristics of the Schottky diode. In this mode of operation, the advantage of the guard ring is maintained while the depletion capacitance and charge storage due to minority-csrrier injection from the p+-n junction which reduce the effectiveness of the Schottky diode as an antisaturation device are eliminated. Copyright © 1984 by The Institute of Electrical and Electronics Engineers, Inc.