CN106229315B - A kind of bidirectional ESD device and manufacturing method thereof - Google Patents

Abstract

The invention discloses a bidirectional ESD device and a manufacturing method thereof. The ESD device comprises: a semiconductor base and a P well arranged in the semiconductor base; an N well formed on one side of the P well; The NPN triode structure on the other side of the P well and the bidirectional diode structure arranged in the N well; the ESD implant layer arranged under the collector and the emitter of the NPN triode structure, the present invention uses the ESD device P-type ESD_IMP is injected under the collector and emitter of the NPN transistor, which further reduces the trigger voltage of the NPN hysteresis effect in the vertical direction, thereby achieving the purpose of reducing the trigger voltage of the entire electrostatic protection structure. The NPN device of the present invention has left-right symmetry structure, the ESD device in the present invention has bidirectional current leakage capability by externally connecting parallel bidirectional diodes.

Description

A kind of bidirectional ESD device and manufacturing method thereof

technical field

The invention relates to the technical field of semiconductor integrated circuits, in particular to an NPN-based bidirectional ESD device and a manufacturing method thereof.

Background technique

The entire life cycle of semiconductor integrated circuits from production to packaging and testing will face various unpredictable electrostatic environments, so that static electricity can be easily introduced into semiconductor integrated circuits, which will cause static electricity loss in semiconductor integrated circuits. Therefore, the design of semiconductor integrated circuits It not only needs to meet the functional requirements, but also has a certain electrostatic protection capability.

At present, in the field of ESD (Electro-Static Discharge) protection design, NPN transistors are widely valued because of their strong ESD discharge capability, but there are two serious defects in this type of device that limit their application: the first defect is the snapback The trigger voltage (hysteresis effect) is very high, because its trigger voltage is mainly limited by the reverse breakdown voltage of the N junction to the P well; the second defect is that the maintenance voltage of the snapback (hysteresis effect) is very low, which can easily lead to latch lock-in effect. Facing these two defects, the industry has proposed various schemes to improve the performance of its snapback (hysteresis effect). The electrostatic protection structure shown in Figure 1 is the closest prior art solution, which injects a P-type ESD_IMP under the N junction to form a vertical NPN, and at the same time, the collector of the NPN is connected in series with a parallel diode and Resistors to increase the sustain voltage of the NPN snapback (hysteresis effect). Specifically, the prior art NPN type ESD device includes a silicon oxide layer (OXIDE) 10, a high-concentration N-type doping (N+) 20, a high-concentration N-type doping (N+) 22, a high-concentration P-type doping (P+) 24. High concentration N-type doping (N+) 26, ESD implant layer (ESD IMP) 40, N well (N-Well) 60, P well (P-Well) 70, resistor R.

The whole ESD device is placed in the P well (P-Well) 70, and two N wells (N-Well) 60 are generated in the P well (P-Well) 70, and there is still a gap between the two N wells (N-Well) 60 P-well (P-Well) 70 isolation (two N-wells (N-Well) 60 cannot overlap), high-concentration N-type doping (N+) 20, high-concentration N-type doping (N+) 22 placed in the left N-well (N-Well) 60 upper part, high-concentration N-type doping (N+) 20, left N-well (N-Well) 60 and high-concentration N-type doping (N+) 22 constitute an NPN structure, high-concentration N-type doping ( N+) 22 is the collector of NPN, high-concentration N-type doping (N+) 20 is the emitter of NPN, high-concentration P-type doping (P+) 24, high-concentration N-type doping (N+) 26 are placed on the right N Well (N-Well) 60 upper part, high-concentration P-type doping (P+) 24, high-concentration N-type doping (N+) 26 constitute a diode structure, high-concentration N-type doping (N+) 20, high-concentration N-type doping Impurity (N+) 22, high-concentration P-type doping (P+) 24, high-concentration N-type doping (N+) 26 are isolated by silicon oxide layer (OXIDE) 10, and ESD implant layer (ESD IMP) 40 is placed in NPN Below the collector (high-concentration N-type doping (N+) 22); use metal to connect high-concentration N-type doping (N+) 22, high-concentration P-type doping (P+) 24 to one end of the resistor R, and the resistor R The other end is connected to the high-concentration N-type doping (N+) 26 ie the ESD cathode K, and the high-concentration N-type doping (N+) 20 is the anode A of the ESD device.

Wherein, the P well (P-Well) 70 is used to isolate the entire ESD device from other devices, and the N well (N-Well) 60 is used to isolate the NPN structure on the left from the diode structure on the right.

Fig. 2 is the equivalent schematic diagram of Fig. 1, viewed from the anode A to the right, since the N well (N-Well) 60 can be regarded as P doping relative to the N+ doping, if there is no ESD implant layer (ESD IMP) 40 , The NPN type ESD device is equivalent to an NPN transistor connected in series with a diode and a parallel network of resistors, adding an ESD implant layer (ESD IMP) 40 under the N junction of the collector to reduce the trigger voltage of snapback (hysteresis effect).

However, the reverse breakdown voltage of the N well and ESD_IMP in the above structure is still relatively high, which leads to a relatively high trigger voltage of the NPN's snapback (hysteresis effect), and because the diode connected in series with the NPN is unidirectional , so the electrostatic protection structure only has one-way discharge capability.

Contents of the invention

For overcoming the deficiency that above-mentioned prior art exists, the object of the present invention is to provide a kind of bidirectional ESD device and manufacture method thereof, it all injects P-type doping (ESD_IMP ), which further reduces the trigger voltage of the NPN snapback (hysteresis effect) in the vertical direction, so as to achieve the purpose of reducing the trigger voltage of the entire electrostatic protection structure. In addition, because the NPN structure is also a left-right symmetrical structure, and a single NPN connected in series The bidirectional diode is replaced with a bidirectional diode, so that the bidirectional ESD device has a bidirectional leakage capability.

For reaching above-mentioned and other object, the present invention proposes a kind of bidirectional ESD device, and this ESD device comprises:

A semiconductor base and a P well disposed in the semiconductor base;

forming an N well on one side of the P well;

An NPN triode structure disposed on the other side of the P well and a bidirectional diode structure disposed in the N well;

An ESD implant layer arranged under the collector and emitter of the NPN triode structure.

Further, high-concentration N-type doping (20) and high-concentration N-type doping (22) are arranged on the upper part of the other side of the P well, and the high-concentration N-type doping (20), the P well The upper part of the other side and the high-concentration N-type doping (22) form the NPN triode structure.

Further, the high-concentration N-type doping (22) is the collector of NPN, the high-concentration N-type doping (20) is the emitter of NPN, and the first ESD implant layer (40) is placed on the Under the high-concentration N-type doping (20), the second ESD implant layer (42) is placed under the high-concentration N-type doping (22).

Further, high-concentration P-type doping (24), high-concentration N-type doping (26), high-concentration P-type doping (28), and high-concentration N-type doping (34) are placed on the upper part of the N well 60 , the high-concentration P-type doping (24) and high-concentration N-type doping (26) constitute a diode structure, and the high-concentration P-type doping (28) and high-concentration N-type doping (34) constitute another diode structure.

Further, the high-concentration N-type doping (20), high-concentration N-type doping (22), high-concentration P-type doping (24), high-concentration N-type doping (26), high-concentration P-type doping Doping (28) and high-concentration N-type doping (34) are separated by a silicon oxide layer (10).

Further, use metal to connect the high-concentration N-type doping (22), high-concentration P-type doping (24), and high-concentration N-type doping (34) to one end of the resistor, and the other end of the resistor is connected to the The high-concentration N-type doping (26) and high-concentration P-type doping (28), the high-concentration N-type doping (20) is the anode of the ESD device.

Further, the N well is arranged on the right side of the P well, and the NPN triode structure is formed on the upper left of the P well.

To achieve the above object, the present invention also provides a method for making a bidirectional ESD device, comprising the steps of:

Step 1, providing a semiconductor substrate;

Step 2, forming a P well in the semiconductor substrate;

Step 3, forming an N well on one side of the P well, and forming an NPN transistor structure on the other side of the P well;

Step 4, generating a bidirectional diode structure in the N well;

Step 5, setting ESD implantation layers under the collector and emitter of the NPN triode structure respectively.

Further, in step 3, high-concentration N-type doping (20) and high-concentration N-type doping (22) are arranged on the upper part of the other side of the P well, and the high-concentration N-type doping (20 ), the upper part of the other side of the P well and the high-concentration N-type doping (22) constitute the NPN triode structure.

Further, in step 4, the high-concentration P-type doping (24), the high-concentration N-type doping (26), the high-concentration P-type doping (28), and the high-concentration N-type doping (34) are placed in In the upper part of the N well 60, the high-concentration P-type doping (24) and high-concentration N-type doping (26) constitute a diode structure, and the high-concentration P-type doping (28), high-concentration N-type doping (34) constitute another diode structure.

Compared with prior art, a kind of two-way ESD device of the present invention and manufacture method thereof, it all injects P-type doping (ESD_IMP) under the collector electrode and the emitter electrode of the NPN triode of this ESD device, further reduces vertical direction The trigger voltage of the NPN snapback (hysteresis effect), so as to achieve the purpose of reducing the trigger voltage of the entire electrostatic protection structure. In addition, because the NPN structure is also a left-right symmetrical structure, and a unidirectional diode connected in series with the NPN is replaced with a bidirectional diode, so that The electrostatic protection structure has bidirectional leakage capability.

Description of drawings

Fig. 1 is the schematic diagram of the electrostatic protection structure of prior art;

Fig. 2 is the equivalent schematic diagram of Fig. 1;

Fig. 3 is the circuit structure diagram of the preferred embodiment of a kind of bidirectional ESE device of the present invention;

Fig. 4 is the equivalent schematic diagram of a preferred embodiment of the present invention;

Fig. 5 is the step flowchart of the manufacture method of a kind of bidirectional ESD device of the present invention;

FIG. 6 is a schematic diagram of an application scenario of the present invention.

Detailed ways

The implementation of the present invention is described below through specific examples and in conjunction with the accompanying drawings, and those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific examples, and various modifications and changes can be made to the details in this specification based on different viewpoints and applications without departing from the spirit of the present invention.

FIG. 3 is a circuit structure diagram of a preferred embodiment of a bidirectional ESD device of the present invention. As shown in Figure 1, a kind of ESD device of the present invention comprises an NPN type triode, the resistor R connected in series with it and the diode connected in parallel with the resistor, specifically, the ESD device includes a semiconductor substrate (not shown), and is arranged on The well 70 in the semiconductor substrate, in a preferred embodiment of the present invention, the well 70 is a P well (P-Well), and an N well (N-Well) 60 is generated on the right side of the P well (P-Well) 70, High-concentration N-type doping (N+) 20, high-concentration N-type doping (N+) 22 are placed in the upper left part of P well (P-Well) 70, high-concentration N-type doping (N+) 20, P well (P- The upper left part of Well) 70 and high-concentration N-type doping (N+) 22 constitute an NPN triode structure, high-concentration N-type doping (N+) 22 is the collector of NPN, and high-concentration N-type doping (N+) 20 is NPN Emitter, high-concentration P-type doping (P+) 24, high-concentration N-type doping (N+) 26 are placed on the upper part of the right N well (N-Well) 60, high-concentration P-type doping (P+) 24, high-concentration N-type doping (N+) 26 Concentration N-type doping (N+) 26 constitutes a diode structure, high-concentration P-type doping (P+) 28, high-concentration N-type doping (N+) 34 constitute another diode structure, high-concentration N-type doping (N+) 20 , High-concentration N-type doping (N+) 22, High-concentration P-type doping (P+) 24, High-concentration N-type doping (N+) 26, High-concentration P-type doping (P+) 28, High-concentration N-type doping The heterogeneous (N+) 34 is isolated with a silicon oxide layer (OXIDE) 10, and the ESD implant layer (ESD_IMP) 40 is placed below the emitter (high concentration N-type doping (N+) 20) of the NPN, and the ESD implant layer (ESD_IMP) ) 42 placed under the collector of NPN (high concentration N-type doping (N+) 22); use metal to connect high concentration N-type doping (N+) 22, high concentration P-type doping (P+) 24, high concentration N Type doping (N+) 34 to one end of resistance R, the other end of resistance R is connected to high concentration N type doping (N+) 26, high concentration P type doping (P+) 28 namely the negative electrode K of bidirectional ESD device of the present invention, High-concentration N-type doping (N+) 20 is the anode A of the bidirectional ESD device of the present invention.

Wherein, the P well (P-Well) 70 is used to isolate the entire ESD device from other devices, and the N well (N-Well) 60 is used to isolate the NPN triode structure on the left from the two diode structures on the right.

Fig. 4 is the equivalent schematic diagram of a preferred embodiment of the present invention, sees from the anode A on the left side of Fig. 3 sectional view to the right, if there is no ESD implantation layer (ESD IMP) 40, ESD implantation layer (ESD IMP) 42, The bidirectional ESD device of the present invention is equivalent to an NPN triode connected in series with a diode and a resistor parallel network, the diode and the resistor parallel network are connected in parallel with the resistor R after the two diodes are reversed, and are respectively added under the emitter N-junction and the collector N-junction The ESD implantation layer (ESD IMP) 40 and the ESD implantation layer (ESD IMP) 42 are added to the ESD implantation layer (ESD IMP) 40 under the N junction of the collector to further reduce the trigger voltage of the snapback (hysteresis effect), Adding bidirectional parallel diodes realizes ESD bidirectional protection.

FIG. 5 is a flow chart of the steps of a manufacturing method of an ESD device according to the present invention. As shown in Figure 5, a kind of manufacture method of ESD device of the present invention comprises the following steps:

Step 501, providing a semiconductor substrate;

In step 502, a well 70 is formed in the semiconductor body. In the present invention, a P-well 70 is formed in the semiconductor body.

In step 503 , an N well 60 is formed on one side of the P well 70 , and an NPN transistor structure is formed on the other side of the P well 70 . Specifically, high-concentration N-type doping (N+) 20 and high-concentration N-type doping (N+) 22 are placed in the upper left part of P well (P-Well) 70, and high-concentration N-type doping (N+) 20, The upper left part of the P well (P-Well) 70 and the high-concentration N-type doping (N+) 22 form an NPN transistor structure, and the high-concentration N-type doping (N+) 22 is the collector of the NPN, and the high-concentration N-type doping ( N+) 20 is the emitter of the NPN.

In step 504 , a bidirectional diode structure is formed in the N well 60 . Specifically, high-concentration P-type doping (P+) 24, high-concentration N-type doping (N+) 26, high-concentration P-type doping (P+) 28, and high-concentration N-type doping (N+) 34 are placed The upper part of the right N well (N-Well) 60, in which high-concentration P-type doping (P+) 24 and high-concentration N-type doping (N+) 26 form a diode structure, and high-concentration P-type doping (P+) 28, high-concentration N-type doping (N+) 34 constitutes another diode structure, two diode structures form a bidirectional diode, high-concentration N-type doping (N+) 20, high-concentration N-type doping (N+) 22, high-concentration P-type doping (P+) 24, high-concentration N-type doping (N+) 26, high-concentration P-type doping (P+) 28, and high-concentration N-type doping (N+) 34 are isolated by silicon oxide layer (OXIDE) 10 .

Step 505, the ESD implant layer (ESD_IMP) 40 is placed under the NPN transistor emitter (high concentration N-type doping (N+) 20), and the ESD implant layer (ESD_IMP) 42 is placed on the NPN transistor collector (high Concentration N-type doping (N+) 22) below.

Step 506, using metal to connect high-concentration N-type doping (N+) 22, high-concentration P-type doping (P+) 24, and high-concentration N-type doping (N+) 34 to one end of the resistor R, and the other end of the resistor R is connected to High-concentration N-type doping (N+) 26, high-concentration P-type doping (P+) 28 are the cathode K of the two-way ESD device of the present invention, and high-concentration N-type doping (N+) 20 is the anode A of the two-way ESD device of the present invention

The present invention injects P-type ESD IMP under the collector and emitter of the NPN transistor on the basis of the existing electrostatic protection structure shown in Figure 1, and converts the N well below the NPN into a P well, Because the N-type ion implantation dose of the N junction of the collector is much higher than the N-type ion implantation dose of the N well, the reverse breakdown voltage of the N junction to the ESD IMP is higher than that of the N well to the ESD IMP. It is much lower, so the trigger voltage of the NPN snapback (hysteresis effect) in the vertical direction can be further reduced, thereby reducing the trigger voltage of the entire electrostatic protection structure. In addition, the NPN structure is also a left-right symmetrical structure, and a one-way connection of the NPN in series The diode is replaced with a bidirectional diode, so the electrostatic protection structure has a bidirectional leakage capability.

The bidirectional ESD device of the present invention can be applied to the protection circuit of the input and output terminals and the protection circuit of the power supply to the ground in the ESD protection circuit to improve the overall ESD protection capability of the chip, as shown in FIG. 6 .

In summary, a kind of bidirectional ESD device of the present invention and manufacturing method thereof, it all injects P-type doping (ESD_IMP) under the collector electrode and the emitter electrode of the NPN transistor of this ESD device, further reduces the NPNsnapback of vertical direction (Hysteresis effect) trigger voltage, so as to achieve the purpose of reducing the trigger voltage of the entire electrostatic protection structure. In addition, because the NPN structure is also a left-right symmetrical structure, and a unidirectional diode connected in series with the NPN is replaced with a bidirectional diode, so that the bidirectional ESD devices have bi-directional bleed capability.

The above-mentioned embodiments only illustrate the principles and effects of the present invention, but are not intended to limit the present invention. Any person skilled in the art can modify and change the above-mentioned embodiments without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention should be listed in the claims.

Claims (10)

1. a kind of bi-directional ESD device, which is characterized in that the ESD device includes:

Semiconductor substrate and the p-well being set in the semiconductor substrate；

Only it is created on the N trap of side in the p-well；

The bilateral diode structure for being set to the NPN triode structure of the p-well other side and being set in the N trap；

The ESD implant layer being set under the collector and emitter of the NPN triode structure, the collector and emitter are High concentration n-type doping, the ESD implant layer be p-type injection, by the collector by the NPN triode structure with it is described Bilateral diode structures in series.

2. a kind of bi-directional ESD device as described in claim 1, it is characterised in that: high concentration n-type doping (20), high concentration N-type Doping (22) is set to the top of the p-well other side, the high concentration n-type doping (20), the p-well other side top with The high concentration n-type doping (22) constitutes the NPN triode structure.

3. a kind of bi-directional ESD device as claimed in claim 2, it is characterised in that: the high concentration n-type doping (22) is NPN Collector, the high concentration n-type doping (20) is the emitter of NPN, and the first ESD implant layer (40) is placed in the high concentration N Type adulterates below (20), and the 2nd ESD implant layer (42) is placed in below the high concentration n-type doping (22).

4. a kind of bi-directional ESD device as claimed in claim 3, it is characterised in that: high concentration p-type adulterates (24), high concentration N-type Doping (26) and high concentration p-type doping (28), high concentration n-type doping (34) are placed in 60 top of N trap, the high concentration P Type adulterates (24), high concentration n-type doping (26) constitutes diode structure, and the high concentration p-type doping (28), high concentration N-type are mixed Miscellaneous (34) constitute another diode structure.

5. a kind of bi-directional ESD device as claimed in claim 4, it is characterised in that: the high concentration n-type doping (20), highly concentrated Spend n-type doping (22), high concentration p-type doping (24), high concentration n-type doping (26), the doping of high concentration p-type (28), high concentration N-type It is isolated between doping (34) with silicon oxide layer (10).

6. a kind of bi-directional ESD device as claimed in claim 5, it is characterised in that: connect the high concentration N-type using metal and mix Miscellaneous (22), high concentration p-type adulterate (24), high concentration n-type doping (34) to one end of resistance, and the other end of the resistance is connected to institute High concentration n-type doping (26), high concentration p-type doping (28) are stated, the high concentration n-type doping (20) is the sun of the ESD device Pole.

7. a kind of bi-directional ESD device as claimed in claim 6, it is characterised in that: the N trap is set on the right side of the p-well, institute State the upper left quarter that NPN triode structure is formed in the p-well.

8. a kind of production method of bi-directional ESD device, includes the following steps:

Step 1 provides semiconductor substrate；

Step 2 forms p-well in semiconductor substrate；

Step 3, only generates a N trap in the side of the p-well, and the other side of Yu Suoshu p-well generates NPN triode structure；

Step 4 generates two-way diode structure in Yu Suoshu N trap；

ESD implant layer, the collector is respectively set under the collector and emitter of Yu Suoshu NPN triode structure in step 5 With transmitting extremely high concentration n-type doping, the ESD implant layer is that p-type is injected, by the collector by the NPN triode Structure and the bilateral diode structures in series.

9. a kind of production method of bi-directional ESD device as described in claim requires 8, it is characterised in that:, will in step 3 High concentration n-type doping (20), high concentration n-type doping (22) are set to the top of the p-well other side, and the high concentration N-type is mixed The top of miscellaneous (20), the p-well other side and the high concentration n-type doping (22) constitute the NPN triode structure.

10. a kind of production method of bi-directional ESD device as described in claim requires 9, it is characterised in that: in step 4, High concentration p-type is adulterated into (24), high concentration n-type doping (26) and high concentration p-type and adulterates (28), high concentration n-type doping (34) It is placed in 60 top of N trap, the high concentration p-type doping (24), high concentration n-type doping (26) constitute diode structure, described High concentration p-type adulterates (28), high concentration n-type doping (34) constitutes another diode structure.