ESD PROTECTION CIRCUIT AND SEMICONDUCTOR DEVICE

Abstract

An ESD protection circuit is connected between a VDD terminal and a Vss terminal and is connected in parallel with an internal circuit which operates at an operating voltage and is damaged at a damage voltage or higher to protect the internal circuit from electrostatic discharge. The ESD protection circuit includes ESD protection elements connected in series. The ESD protection elements are transistors, diode elements, or a combination thereof. A sum of current-voltage characteristics of the ESD protection elements at a voltage higher than the operating voltage is higher than the operating voltage and lower than the damage voltage, until reaching a discharge current value or higher capable of protecting the internal circuit.

Description

Claims

1. An ESD protection circuit, which is connected between a first terminal and a second terminal and is connected in parallel with a protected circuit that operates at an operating voltage and is damaged at a damage voltage or higher to protect the protected circuit from electrostatic discharge, the ESD protection circuit comprising: a plurality of ESD protection elements connected in series, wherein the plurality of ESD protection elements are transistors, diode elements, or a combination thereof, anda sum of current-voltage characteristics of the plurality of ESD protection elements at a voltage higher than the operating voltage is higher than the operating voltage and lower than the damage voltage, until reaching a discharge current value or higher capable of protecting the protected circuit.

2. The ESD protection circuit according to claim 1, wherein a breakdown voltage of the sum of the current-voltage characteristics of the plurality of ESD protection elements is higher than the operating voltage.

3. The ESD protection circuit according to claim 1, wherein the plurality of ESD protection elements comprise the transistor, anda holding voltage of the sum of the current-voltage characteristics of the plurality of ESD protection elements is higher than the operating voltage.

4. The ESD protection circuit according to claim 1, wherein the transistor is a MOS transistor or a bipolar transistor.

5. The ESD protection circuit according to claim 4, wherein the MOS transistor is an N-channel MOS transistor or a P-channel MOS transistor and has a withstand voltage equal to or different from a withstand voltage of another of the ESD protection elements.

6. The ESD protection circuit according to claim 5, wherein the plurality of ESD protection elements comprise both the N-channel MOS transistor and the P-channel MOS transistor.

7. The ESD protection circuit according to claim 4, wherein the MOS transistor has a DMOS structure.

8. The ESD protection circuit according to claim 1, wherein the plurality of ESD protection elements comprise both the transistor and the diode element.

9. The ESD protection circuit according to claim 1, wherein the diode element has a withstand voltage equal to or different from a withstand voltage of another of the ESD protection elements.

10. The ESD protection circuit according to claim 1, wherein a breakdown voltage of at least one ESD protection element among the plurality of ESD protection elements is different from a breakdown voltage of another of the ESD protection elements.

11. A semiconductor device, wherein the ESD protection circuit according to claim 1 and a protected circuit to be protected by the ESD protection circuit from electrostatic discharge are connected in parallel.