# US 2014/0151745 A1 · Electrostatic discharge protective device

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- Number: US 2014/0151745 A1
- Document ID: US20140151745A1
- Status: Published application
- Kind: A1
- Application number: 14/130,427
- Filed: 2012-08-09
- Published: 2014-06-05
- Earliest claimed: 2011-09-29
- Assignees: Csmc Technologies Fabi Co., Ltd.
- Inventors: Meng Dai
- Web page: https://patentgrep.com/patent/US20140151745A1

## CPC

- H10W 42/60: protecting against electrostatic charges or discharges, e.g. Faraday shields (integrated devices comprising arrangements for electrical protection H10D89/60)
- H10D 18/251: {Lateral thyristors}
- H10D 89/713: {including a PNP transistor and a NPN transistor, wherein each of said transistors has its base region coupled to the collector region of the other transistor, e.g. silicon controlled rectifier [SCR] devices}
- H10W: GENERIC PACKAGES, INTERCONNECTIONS, CONNECTORS OR OTHER CONSTRUCTIONAL DETAILS OF DEVICES COVERED BY CLASS H10
- H10D: INORGANIC ELECTRIC SEMICONDUCTOR DEVICES

## Abstract

An electrostatic discharge (ESD) protection device is provided. A proper trigger voltage is determined by providing an ESD doped injection layer into a PNPN structure and adjusting the injection energy and dosage of the ESD doped injection layer; a proper holding voltage is obtained by adjusting the size of the ESD doped injection layer, thus preventing the latch-up. The self-isolation effect of the electrostatic discharge protection device is formed on the basis of an epitaxial wafer high voltage process or a silicon-on-insulator (SOI) wafer high voltage process, the ESD protective device of the present invention can prevent the device from being falsely triggered due to noise interference. Compared with other known ESD protection devices, the device has the same electrostatic protection ability, much smaller area, and much lower cost.

## Claims

### Claim 1

An electrostatic discharge protection device, comprising an electrostatic discharge protection unit, wherein the electrostatic discharge protection unit comprises:
a P-type substrate;
a P-type epitaxial layer disposed on the P-type substrate;
an N-type buried layer disposed between the P-type substrate and the P-type epitaxial layer;
a first N-type well disposed on the N-type buried layer and inside the P-type epitaxial layer;
a first P-type well disposed on the N-type buried layer and inside the P-type epitaxial layer, the first P-type well being adjacent to the first N-type well;
a second N-type well disposed on the N-type buried layer and inside the P-type epitaxial layer, and adjacent to the first P-type well;
an ESD doped injection layer disposed in the first P-type well and the first N-type well;
a first N+ region and a first P+ region disposed in the ESD doped injection layer; and
a second N+ region and a second P+ region disposed outside the ESD doped injection layer, wherein the second N+ region and the second P+ region are disposed in the first N-type well or the first P-type well with a conductivity type opposite to the ESD doped injection layer.

### Claim 2 (depends on 1)

The electrostatic discharge protection device according to claim 1, wherein a number of the electrostatic discharge protection unit is at least two, the at least two electrostatic discharge protection units are connected in series.

### Claim 3 (depends on 2)

The electrostatic discharge protection device according to claim 2, wherein the electrostatic discharge protection units are connected in series by a second P-type well.

### Claim 4 (depends on 3)

The electrostatic discharge protection device according to claim 3, wherein the second P-type well is disposed inside the P-type epitaxial layer, the second P-type well is connected to the second N-type well of a former electrostatic discharge protection unit, and connected to the first N-type well of the latter electrostatic discharge protection unit.

### Claim 5 (depends on 1)

The electrostatic discharge protection device according to claim 1, wherein the ESD doped injection layer is N-type doping or P-type doping.

### Claim 6 (depends on 2)

The electrostatic discharge protection device according to claim 2, wherein the ESD doped injection layer is N-type doping or P-type doping, the doping types of the ESD doped injection layers of two adjacent electrostatic discharge protection units are different.

### Claim 7 (depends on 1)

The electrostatic discharge protection device according to claim 1, further comprising:
a first electrode connected to the first N+ region and the first P+ region;
a second electrode connected to the second N+ region and the second P+ region.

### Claim 8 (depends on 1)

The electrostatic discharge protection device according to claim 1, wherein a trigger voltage of the electrostatic discharge protection device is determined by an injection dose and energy of the ESD doped injection layer.

### Claim 9 (depends on 1)

The electrostatic discharge protection device according to claim 1, wherein a holding voltage of the electrostatic discharge protection device is determined by a size of the ESD doped injection layer.

### Claim 10 (depends on 1)

The electrostatic discharge protection device according to claim 1, wherein the electrostatic discharge protection device is manufactured by an epitaxial wafer high voltage process.

### Claim 11

An electrostatic discharge protection device, comprising an electrostatic discharge protection unit, wherein the electrostatic discharge protection unit comprises:
a P-type substrate;
an oxide layer formed on the P-type substrate;
a first N-type well formed on the oxide layer;
a first P-type well formed on the oxide layer and adjacent to the first N-type well;
a first trench defined on the oxide layer and adjacent to the first N-type well;
a second trench defined on the oxide layer and adjacent to the first P-type well;
an ESD doped injection layer formed in the P-type well and the first N-type well;
a first N+ region and a first P+ region disposed in the ESD doped injection layer in parallel;
a second N+ region and a second P+ region disposed outside the ESD doped injection layer in parallel, wherein the second N+ region and the second P+ region are disposed in the first N-type well or the first P-type well with a conductivity type opposite to the ESD doped injection layer.

### Claim 12 (depends on 11)

The electrostatic discharge protection device according to claim 11, wherein a number of the electrostatic discharge protection unit is at least two, the at least two electrostatic discharge protection units are connected in series.

### Claim 13 (depends on 12)

The electrostatic discharge protection device according to claim 12, wherein the electrostatic discharge protection units are connected in series by a spacer structure.

### Claim 14 (depends on 13)

The electrostatic discharge protection device according to claim 13, wherein the spacer structure is formed on the oxide layer, the spacer structure is adjacent to the second trench of a former electrostatic discharge protection unit, and adjacent to the first trench of a latter electrostatic discharge protection unit.

### Claim 15 (depends on 13)

The electrostatic discharge protection device according to claim 13, wherein the spacer structure is a P-type well or an N-type well.

### Claim 16 (depends on 11)

The electrostatic discharge protection device according to claim 11, wherein the ESD doped injection layer is N-type doping or P-type doping.

### Claim 17 (depends on 12)

The electrostatic discharge protection device according to claim 12, wherein the ESD doped injection layer is N-type doping or P-type doping, the doping types of the ESD doped injection layers of two adjacent electrostatic discharge protection units are different.

### Claim 18 (depends on 17)

The electrostatic discharge protection device according to claim 17, further comprises:
a first electrode connected to the first N+ region and the first P+ region;
a second electrode connected to the second N+ region and the second P+ region.

### Claim 19 (depends on 11)

The electrostatic discharge protection device according to claim 11, wherein a trigger voltage of the electrostatic discharge protection device is determined by an injection dose and energy of the ESD doped injection layer.

### Claim 20 (depends on 11)

The electrostatic discharge protection device according to claim 11, wherein a holding voltage of the electrostatic discharge protection device is determined by a size of the ESD doped injection layer.