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US 2008/0259518 A1Published application
Low Operating Voltage Electro-Static Discharge Device And Method
AssigneeCalifornia Micro Devices Corporation
InventorsHarry Yue Gee, Umesh Sharma
Life of this patent
Estimating the term…
Abstract
The present invention describes ESD apparatus, methods of forming the same, and methods of providing ESD protection. In certain aspects, the invention achieves the desired turn-on voltage and maintains low leakage in the ESD apparatus, and the methods of providing ESD protection. In one aspect, a zener diode that has a positive trigger voltage is used to quickly turn-on a transistor. In another aspect, different zener diodes that have positive and negative trigger voltages, respectively, are used to quickly turn on a transistor. In still another aspect, a linearly graded P-region is used to implement the ESD device of the present invention.
Claims17
An apparatus that discharges an electrostatic charge, the apparatus comprising:
- a semiconductor integrated circuit, the semiconductor integrated circuit including:
- an input;
- a ground connection that provides a discharge path for the electrostatic charge;
- and
- an electrostatic discharge device connected between the input and the ground connection that has low leakage at an operating voltage, a positive trigger voltage, a positive clamping voltage, and wherein the positive clamping voltage is substantially independent of the positive trigger voltage, such that the device turns on in order to dissipate the electrostatic charge, the device including:
- an N+ substrate region that is connected to the ground connection,
- a P epitaxial region that is formed over the N+ anode region that has a thickness and a doping concentration that together substantially determine the positive clamping voltage, and
- an N+ electrode region that is formed within the P epitaxial region, such that a side wall surface of the N+ electrode region around a side wall surface of the P epitaxial region, the N+ electrode region connected to the input;
- and
- a P+ sidewall region formed over the P epitaxial region in a continuous region adjacent the sidewall surface of the N+ electrode region, wherein the P+ sidewall region and the N+ electrode form a zener diode that injects current into the P epitaxial region and thereby causes turn-on of a transistor formed by the N+ electrode region, the P region and the N+ substrate region, wherein a concentration of the P+ sidewall region assists in determining the positive trigger voltage without substantially having an effect on the positive clamping voltage.
7 more elements
An apparatus that discharges an electrostatic charge, the apparatus comprising:
- a semiconductor integrated circuit, the semiconductor integrated circuit including:
- an input;
- a ground connection that provides a discharge path for the electrostatic charge;
- an electrostatic discharge device connected between the input and the ground connection that has low leakage at an operating voltage, a positive trigger voltage, a negative trigger voltage, a positive clamping voltage, and a negative clamping voltage, and wherein the positive and the negative clamping voltages are substantially independent of the positive and the negative trigger voltages, such that the device turns on in order to dissipate the electrostatic charge, the device including:
- an N+ substrate region that is connected to the ground connection,
- a P epitaxial region that is formed over the N+ anode region that has a thickness and a doping concentration that together substantially determine the positive and negative clamping voltages, and
- an N+ electrode region that is formed within the P epitaxial region, such that a side wall surface of the N+ cathode region around a side wall surface of the P epitaxial region, the N+ electrode region connected to the input;
- a P+ sidewall region formed over the P epitaxial region in a continuous region between a portion of the sidewall surface of the N+ substrate region and a portion of the sidewall surface of the N+ electrode region;
- and
- an N+ region that extends between the P+ sidewall region and the N+ substrate region;
- wherein the P+ sidewall region and the N+ cathode form a positive zener diode that injects positive current into the P epitaxial region and thereby causes turn-on of a transistor formed by the N+ electrode region, the P epitaxial region and the N+ substrate region,
- wherein the P+ sidewall region and the N+ region form a negative zener diode that injects negative current into the P epitaxial region and thereby causes turn-on of a transistor formed by the N+ electrode region, the P epitaxial region and the N+ substrate region, and
- wherein a P+ concentration of the P+ sidewall region assists in determining the positive and the negative trigger voltages without substantially having an effect on the positive and the negative clamping voltages.
10 more elements
Dependencies are inferred from the claim text.