Phantom ESD protection circuit employing E-field crowding

Abstract

Abstract An integrated circuit chip having improved static discharge protection comprises a semiconductor substrate with a major surface, a plurality of transistors that are integrated into the surface, patterned conductors that interconnect the transistors and route input signals to the transistors, with the patterned conductors including metal pads for receiving the input signals from an external source; wherein the improvement comprises respective diodes which are integrated into the surface directly beneath the metal pads, and which connect the pads to the substrate and conduct electrostatic charge therebetween. With this structure, no additional chip space is required over that which is used by the transistors which are being protected since the diodes are hidden in the normally unused chip space beneath the pads. Also with this structure, the diodes can be large since the metal pads are inherently large enough to receive a bonding wire; and thus the diodes have a large current-carrying capacity and a small series resistance. Preferably, the metal pads have sharp corners of 90° or less which tend to accumulate any electrostatic charge, and the diodes are disposed beneath the metal pads at these corners. Since the diodes are located where the charge tends to accumulate, they are more effective in dissipating that charge than if they were located elsewhere.

Inventors

• 👤 Xiaonan Zhang

Bibliographic Details