Low-capacitance SCR structure ESD protection device
By introducing a Schottky barrier diode to assist triggering in the SCR device, the low-capacitance SCR structure is optimized, solving the problems of slow response speed and overheating caused by current concentration. This results in faster response and lower capacitance, improving the reliability and high-temperature performance of the device.
Patent Information
- Application Number
- CN202520424328.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-11
- Publication Date
- 2026-01-30
- Estimated Expiration
- 2035-03-11
AI Technical Summary
Existing low-capacitance SCR structure ESD protection devices have slow response speed in high-frequency applications, and the current concentration leads to local overheating, making it difficult to meet the requirements of fast response and reliability.
A low-capacitance SCR structure with Schottky barrier metal anode assisted triggering is adopted. By introducing a Schottky barrier diode into the SCR device, the PN junction assisted triggering structure is improved, high-concentration impurity injection is reduced, and the device design is optimized to reduce the capacitance value and improve the response speed.
It improves the response speed and reliability of the device, reduces the capacitance value, improves high-temperature performance and current distribution, and meets the requirements of high-frequency applications.
Smart Images
Figure CN223859541U_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The utility model relates to the field of safety protection, concretely is a low capacitance SCR structure ESD protection device. BACKGROUND
[0002] At present, with the rapid development of communication technology, the demand of high performance ESD protection device (Electrostatic Discharge, namely static electricity discharge protection device) applied to high speed data port is increasing day by day. With the higher requirement of data transmission, the development trend of such protection device is to have lower capacitance and lower clamping voltage. SCR structure device is used for voltage transient and surge protection, has the advantages of small clamping coefficient, small size, fast response, small leakage current and high reliability. Benefited from the low maintenance voltage brought by snapback phenomenon (static echo effect, a kind of static electricity release protection mechanism, commonly used in integrated circuits), the clamping voltage of SCR device (Silicon Controlled Rectifier, namely silicon controlled rectifier) is lower when discharging ESD current.
[0003] Low capacitance SCR generally selects high resistivity (> 50Ω*cm) substrate material, so the trigger voltage of conventional structure SCR is very high, about 50-200V, much higher than the withstand voltage of low voltage device in the protected circuit. The existing discrete SCR structure protection scheme is to set the PN junction of auxiliary trigger in the SCR structure to realize, as shown in Figure 1 、 Figure 2
[0004] The PN junction of auxiliary trigger on both sides TN and ZP (N-type semiconductor region, P-type semiconductor region) is formed by high concentration impurity injection annealing, and the junction capacitance is very large. In order to meet the design requirement of low capacitance, it will be designed as several stripes across NWELL (N-type well) and PWELL (P-type well) when layout (low impedance path). Because the breakdown voltage of TN / ZP junction of auxiliary trigger is much lower than the junction formed by NWELL and PSUB (P-type substrate), most of the current will flow through these TN / ZP stripes at the moment of SCR opening, causing local overheating and burning out the device. At the same time, the switching response speed of silicon-based PN junction is slow, which will lead to the opening response speed of SCR not timely, and it is difficult to meet the demand of fast response in high frequency application, which needs to be improved. INVENTION CONTENTS
[0005] The utility model discloses a low capacitance SCR structure ESD protection device, to solve the problem of above -mentioned background art.
[0006] To realize above -mentioned purpose, the utility model provides the following technical scheme:
[0007] A low capacitance SCR structure ESD protection device, including first conductive type substrate, first conductive type substrate's top is provided with first second conductive type trap area, first first conductive type trap area, second second conductive type trap area, second first conductive type trap area in proper order, first second conductive type trap area is provided with first second conductive type source area, first first conductive type source area, and first second conductive type source area, first first conductive type source area are commonly used as SCR structure device anode lead-out, and second second conductive type trap area is provided with second second conductive type source area, and second first conductive type trap area is provided with second first conductive type source area, and second second conductive type source area, second first conductive type source area are commonly used as SCR device's cathode lead-out, and first second conductive type trap area and first first conductive type trap area top are connected through Schottky barrier metal anode.
[0008] As the further scheme of the utility model: the material of first conductive type substrate is PSUB.
[0009] As the further scheme of the utility model: first second conductive type trap area, second second conductive type trap area, first second conductive type source area, second second conductive type source area are formed by injecting P element, and first second conductive type trap area, second second conductive type trap area injection dose is 1e11~1e18, and first second conductive type source area, second second conductive type source area injection dose is 1e12~1e18.
[0010] As the further scheme of the utility model: first first conductive type trap area, second first conductive type trap area, first first conductive type source area, second first conductive type source area are formed by injecting B element, and first first conductive type trap area, second first conductive type trap area injection dose is 1e11~1e18, and first first conductive type source area, second first conductive type source area injection dose is 1e12~1e18.
[0011] As the further scheme of the utility model: Schottky barrier metal anode is metal material, and the metal material includes Ni, NiAg alloy.
[0012] Compared with the prior art, the beneficial effects of the utility model are that: the structure of the Schottky diode auxiliary trigger can improve the problems of the local overheating caused by the un-timely opening response speed and current concentration of the conventional low-capacitance SCR device adopting the N-type and P-type impurity high-concentration injection to form a PN junction auxiliary trigger structure, improve the reliability of the device, and further compress the overall size of the auxiliary trigger structure, such as reducing the number of stripes or reducing the size of the stripes, by the better high-temperature performance and current capacity of the Schottky junction, so as to further reduce the capacitance value of the SCR protection device. BRIEF DESCRIPTION OF DRAWINGS
[0013] Figure 1 It is a kind of low-capacitance SCR structure ESD protection device's schematic diagram.
[0014] Figure 2 It is a kind of low-capacitance SCR structure ESD protection device's structural diagram.
[0015] Figure 3 It is a kind of low-capacitance SCR structure ESD protection device's mixed schematic diagram.
[0016] In the drawing: 1-first conductive type substrate, 2-first second conductive type well region, 3-second second conductive type well region, 4-first first conductive type well region, 5-second first conductive type well region, 6-first second conductive type source region, 7-second second conductive type source region, 8-first first conductive type source region, 9-second first conductive type source region, 10-Schottky barrier metal anode. DETAILED DESCRIPTION
[0017] The technical solutions in the embodiments of the utility model will be clearly and completely described below with reference to the drawings in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, rather than all the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by those skilled in the art without creative labor fall within the protection scope of the utility model.
[0018] Please refer to Figure 1 And Figure 3A low-capacitance SCR structure ESD protection device, comprising a first conductive type substrate 1, a first second conductive type well region 2, a first first conductive type well region 4, a second second conductive type well region 3, and a second first conductive type well region 5 are sequentially arranged above the first conductive type substrate 1, a first second conductive type source region 6 and a first first conductive type source region 8 are arranged in the first second conductive type well region 2, the first second conductive type source region 6 and the first first conductive type source region 8 are commonly used as an anode lead-out of the SCR structure device, a second second conductive type source region 7 is arranged in the second second conductive type well region 3, a second first conductive type source region 9 is arranged in the second first conductive type well region 5, the second second conductive type source region 7 and the second first conductive type source region 9 are commonly used as a cathode lead-out of the SCR device, and a Schottky barrier metal anode 10 is connected above the first second conductive type well region 2 and the first first conductive type well region 4.
[0019] In the embodiment, please refer to Figure 1 The material of the first conductive type substrate 1 is PSUB.
[0020] PSUB is a P-type semiconductor substrate.
[0021] In the embodiment, please refer to Figure 1 The first second conductive type well region 2, the second second conductive type well region 3, the first second conductive type source region 6, and the second second conductive type source region 7 are formed by injecting P elements, the injection dose of the first second conductive type well region 2 and the second second conductive type well region 3 is 1e11-1e18, and the injection dose of the first second conductive type source region 6 and the second second conductive type source region 7 is 1e12-1e18.
[0022] The injection of P elements is N-type doping in intrinsic Si (intrinsic silicon is a special state of semiconductor material, which refers to a silicon single crystal with complete crystal lattice and no impurities), to form an N-type source region, and the injection dose of the P elements falls within this range.
[0023] In the embodiment, please refer to Figure 1 The first first conductive type well region 4, the second first conductive type well region 5, the first first conductive type source region 8, and the second first conductive type source region 9 are formed by injecting B elements, the injection dose of the first first conductive type well region 4 and the second first conductive type well region 5 is 1e11-1e18, and the injection dose of the first first conductive type source region 8 and the second first conductive type source region 9 is 1e12-1e18.
[0024] The injection of B elements is P-type doping in intrinsic Si, to form a P-type source region, and the injection dose of the B elements falls within this range.
[0025] In the embodiment, refer to Figure 1 The Schottky barrier metal anode 10 is a metal material, and the metal material includes Ni and a NiAg alloy.
[0026] The Schottky barrier metal anode 10 is a plurality of floating metal strips located on the surface of the wafer and bridging over the first second-conductivity-type well region 2 and the first first-conductivity-type well region 4 (also over the first-conductivity-type substrate 1), and can be, but is not limited to, a metal material such as Ni and a NiAg alloy.
[0027] The working principle of the utility model is: refer to Figure 2 and Figure 3 The main body structure of the device is an NPN structure Qn composed of the first second-conductivity-type source region 6, the first second-conductivity-type well region 2, the first-conductivity-type substrate 1, the first first-conductivity-type well region 4 and the second second-conductivity-type well region 3, and a PNP structure Qp composed of the first first-conductivity-type source region 8, the first second-conductivity-type well region 2, the first-conductivity-type substrate 1, the second first-conductivity-type well region 5 and the second first-conductivity-type source region 9, which are coupled to form an SCR device.
[0028] The well resistance of the first second-conductivity-type well region 2 is a parasitic resistance in series with the base of the transistor Qp, and the substrate resistance of the first-conductivity-type substrate 1 and the well resistance of the second first-conductivity-type well region 5 together constitute a parasitic resistance in series with the base of the transistor Qn. The first-conductivity-type substrate Schottky barrier metal anode 10 forms a back-to-back series Schottky barrier diode auxiliary SCR device trigger with the first second-conductivity-type well region 2 and the first first-conductivity-type well region 4. When the SCR is working, the first second-conductivity-type well region 2 is connected to a positive potential, the first first-conductivity-type well region 4 is floating, the Schottky junction formed by the first second-conductivity-type well region 2 and the first-conductivity-type substrate Schottky barrier metal anode 10 is reverse biased, and the Schottky junction formed by the first-conductivity-type substrate Schottky barrier metal anode 10 and the first first-conductivity-type well region 4 is forward biased. Since the opening voltage of the forward biased Schottky junction is very low, the trigger voltage of the SCR is mainly determined by the breakdown voltage of the reverse biased Schottky junction formed by the first second-conductivity-type well region 2 and the first-conductivity-type substrate Schottky barrier metal anode 10.
[0029] A first conductive type substrate Schottky barrier metal anode 10 is deposited on the surface of the first conductive type substrate 1, and is connected across the first second conductive type well region 2 and the first first conductive type well region 4 in the SCR structure, forming a series of N-type Schottky junction and P-type Schottky junction with the first second conductive type well region 2 and the first first conductive type well region 4 respectively. When the first second conductive type well region 2 is connected to a positive potential and the first first conductive type well region 4 is floating during the operation of the SCR, the first second conductive type well region 2 and the first conductive type substrate Schottky barrier metal anode 10 form a reverse-biased Schottky barrier. The first conductive type substrate Schottky barrier metal anode 10 and the first first conductive type well region 4 form a forward-biased Schottky barrier. Since the opening voltage of the forward-biased Schottky barrier is very low, the trigger voltage of the SCR device is mainly determined by the breakdown voltage of the reverse-biased N-type Schottky diode formed by the first second conductive type well region 2 and the first conductive type substrate Schottky barrier metal anode 10. The Schottky junction has faster opening speed, stronger surge capacity and better high-temperature performance than the silicon-based PN junction, and has lower noise level under high-frequency signals.
[0030] The structure of the Schottky diode auxiliary trigger of the utility model can improve the problems of local overheating caused by the non-timely opening response speed and current concentration of the conventional low-capacitance SCR device adopting the N-type and P-type impurity high-concentration injection PN junction auxiliary trigger structure, improve the reliability of the device, and further compress the overall size of the auxiliary trigger structure, such as reducing the number of stripes or reducing the size of the stripes, by the better high-temperature performance and current capacity of the Schottky junction, so that the capacitance value of the SCR protection device is further reduced.
[0031] It is apparent for those skilled in the art that the utility model is not limited to the details of the above exemplary embodiments, and the utility model can be realized in other specific forms without departing from the spirit or essential characteristics of the utility model. Therefore, the embodiments should be regarded as exemplary and non-limiting from any point of view.
[0032] In addition, it should be understood that, although the present specification is described in terms of embodiments, not every embodiment contains only one independent technical solution, and the description manner of the specification is only for the sake of clarity, and those skilled in the art should regard the specification as a whole, and the technical solutions in each embodiment can be combined appropriately to form other embodiments that can be understood by those skilled in the art.
Claims
1. A low-capacitance SCR structure ESD protection device, characterized in that, The low-capacitance SCR structure ESD protection device comprises a first conductive type substrate, a first second conductive type well region, a first first conductive type well region, a second second conductive type well region and a second first conductive type well region are sequentially arranged above the first conductive type substrate, a first second conductive type source region and a first first conductive type source region are arranged in the first second conductive type well region, the first second conductive type source region and the first first conductive type source region are commonly used as an anode lead-out of the SCR structure device, a second second conductive type source region is arranged in the second second conductive type well region, a second first conductive type source region is arranged in the second first conductive type well region, and the second second conductive type source region and the second first conductive type source region are commonly used as a cathode lead-out of the SCR device, and the first second conductive type well region and the first first conductive type well region are connected through a Schottky barrier metal anode.
2. The low-capacitance SCR structure ESD protection device of claim 1, wherein, The material of the first conductive type substrate is PSUB.
3. The low-capacitance SCR structure ESD protection device of claim 1, wherein, The first second conductive type well region, the second second conductive type well region, the first second conductive type source region and the second second conductive type source region are formed by injecting P elements, the injection dose of the first second conductive type well region and the second second conductive type well region is 1e11-1e18, and the injection dose of the first second conductive type source region and the second second conductive type source region is 1e12-1e18.
4. The low-capacitance SCR structure ESD protection device of claim 1, wherein, The first first conductive type well region, the second first conductive type well region, the first first conductive type source region and the second first conductive type source region are formed by injecting B elements, the injection dose of the first first conductive type well region and the second first conductive type well region is 1e11-1e18, and the injection dose of the first first conductive type source region and the second first conductive type source region is 1e12-1e18.
5. The low-capacitance SCR structure ESD protection device according to any one of claims 1 to 4, wherein, The Schottky barrier metal anode is a metal material, and the metal material comprises Ni and a NiAg alloy.