Bidirectional asymmetric voltage surge protection device with transverse structure

Abstract

The utility model discloses a bidirectional asymmetric voltage surge protection device with a transverse structure, which relates to the field of protection tubes and comprises a wafer, a first conductive type substrate is arranged on the wafer, a plurality of first second conductive type well regions are arranged in a P + region of the wafer, and a plurality of second conductive type well regions are arranged in a P + region of the wafer. Compared with the prior art, the single-direction TVS chip has the advantages that the single-direction TVS chip is simple in overall structure and good in protection capacity when dealing with circuits needing different protection voltage values in the forward direction and the reverse direction, cost is saved compared with two single-direction TVS chips with different voltages, and the single-direction TVS chip is high in reliability and high in reliability. The space of the circuit board is saved; the first second conductive type well region and the second second conductive type well region are arranged alternately, so that the effective PN junction area of the device is increased, the distribution of surge current in the device during working is improved, the performance of the device is improved, and the production cost is reduced.

Description

TECHNICAL FIELD

[0001] The utility model relates to the protection tube field, concretely is a two -way asymmetric voltage surge protection device of horizontal structure. BACKGROUND

[0002] When the transient voltage suppressor TVS tube endures instantaneous high energy impact, it can suddenly reduce its impedance at a very high speed, clamp the voltage between its two ends at a predetermined value, thereby ensuring that the following circuit elements are not damaged by transient high energy impact. Because the TVS tube has the advantages of fast response time, large transient power, low capacitance, low leakage current, small breakdown voltage deviation, easy control of clamping voltage, small size, easy installation, etc., it has been widely used in computer systems, communication equipment, consumer electronics, power supplies, household appliances and other fields.

[0003] Now in the application of network port and various interfaces, different protection voltages are often needed at both ends of the line. The existing two-way asymmetric TVS chip is mainly realized in two ways. One is to use two different voltage unidirectional TVS chips to form a two-way TVS tube. This scheme has high packaging cost and large size of finished product, which cannot meet the miniaturization requirement in some applications. The other scheme is to realize two-way asymmetric voltage surge protection by different PN junction breakdown voltages on both sides of the longitudinal PNP or NPN structure. Because the current flowing through the line at both ends is consistent, that is, the surge (IPP) capacity requirement of the protection device on both sides of the line in actual application is consistent, and the size of the chip in the above protection scheme depends on the power requirement of the high voltage side, the chip area is redundant for the low voltage side, which will cause waste of cost.

[0004] In summary, the existing two-way asymmetric TVS chip has high cost and needs to be improved. UTILITY MODEL CONTENTS

[0005] The utility model aims at providing a two-way asymmetric voltage surge protection device of horizontal structure to solve the problems in the above background technology.

[0006] To achieve the above purpose, the utility model provides the following technical scheme:

[0007] A bidirectional asymmetric voltage surge protection device of lateral structure comprises a wafer, a first conductive type substrate is arranged on the wafer, a plurality of first second conductive type well regions are arranged on a P+ region of the wafer, a plurality of second second conductive type well regions are arranged on a P++ region of the wafer, the first second conductive type well regions and the second second conductive type well regions are arranged alternately (the two second conductive type well regions are arranged alternately), a SiO2 protective layer is arranged on the surface of the wafer, a first metal electrode is connected to the first second conductive type well regions, and a second metal electrode is connected to the second second conductive type well regions.

[0008] As a further scheme of the utility model, the first conductive type substrate has a thickness of 100-400 um and a resistivity of 0.005-100 Ω*cm.

[0009] As a further scheme of the utility model, the first second conductive type well regions have an impurity concentration of a1.

[0010] As a further scheme of the utility model, the second second conductive type well regions have an impurity concentration of a2.

[0011] As a further scheme of the utility model, the SiO2 protective layer has a thickness of 50-10000 A (1 A=0.1 nm).

[0012] Compared with the prior art, the utility model has the advantages that: the utility model has a simple overall structure, good protection capability when a circuit needs different protection voltage values in the positive and negative directions, cost saving and circuit board space saving compared with two one-way TVS chips with different voltages, the first second conductive type well regions and the second second conductive type well regions are arranged alternately, the effective PN junction area of the device is increased, the distribution of surge current in the device during operation is improved, the performance of the device is improved, and the production cost is reduced. BRIEF DESCRIPTION OF DRAWINGS

[0013] Figure 1 It is a structure diagram of a bidirectional asymmetric voltage surge protection device of lateral structure.

[0014] Figure 2 It is a schematic view of the first second conductive type well regions and the second second conductive type well regions arranged alternately.

[0015] Figure 3 It is a sectional view of A section of the first second conductive type well regions and the second second conductive type well regions arranged alternately.

[0016] Figure 4 It is a schematic view of a bidirectional asymmetric voltage surge protection device of lateral structure.

[0017] In the figure: 1 - first conductive type substrate, 2 - first second conductive type well region, 3 - second second conductive type well region, 4 - SiO2 protective layer, 5 - first metal electrode, 6 - second metal electrode. DETAILED DESCRIPTION

[0018] 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.

[0019] Please refer to Figure 1 , Figure 2 , a bidirectional asymmetric voltage surge protection device of lateral structure, comprising a wafer, the wafer is provided with a first conductive type substrate 1, a plurality of first second conductive type well regions 2 are arranged in the P+ region of the wafer, a plurality of second second conductive type well regions 3 are arranged in the P++ region of the wafer, the first second conductive type well regions 2 and the second second conductive type well regions 3 are arranged alternately (the arrangement mode of the two second conductive type well regions is alternately arranged), the wafer surface is provided with a SiO2 protective layer 4, the first second conductive type well regions 2 are connected with a first metal electrode 5, and the second second conductive type well regions 3 are connected with a second metal electrode 6.

[0020] In the embodiment, please refer to Figure 1 , the first conductive type substrate 1 has a thickness of 100-400 um and a resistivity of 0.005-100 Ω*cm.

[0021] The thickness of the wafer produced by Fab (in the semiconductor industry, Fab refers to a factory for producing integrated circuits and its manufacturing process) is in the range of 100-400 um. The substrate resistivity and the impurity concentration of the following well regions determine the breakdown voltage of the PN junction. The substrate material used by us has a resistivity in the range of 0.005-100 Ω*cm.

[0022] In the embodiment, please refer to Figure 1 , the first second conductive type well regions 2 have an impurity concentration a1.

[0023] In the embodiment, please refer to Figure 1 , the second second conductive type well regions 3 have an impurity concentration a2.

[0024] The impurity concentrations a1 and a2 are to illustrate that the impurity concentrations of the two regions are different, and the impurity concentration range of the region falls in 1e14-1e18.

[0025] Please refer toFigure 3 The size d1 and d2 of the first second-conductivity-type well region 2 and the second second-conductivity-type well region 3 can be adjusted so that the chip area is effectively utilized.

[0026] The first second-conductivity-type well region 2 and the second second-conductivity-type well region 3 are arranged alternately, that is, the layout is in the form of a finger, which increases the effective PN junction area of the device and improves the distribution of surge current in the device during operation, improves the performance of the device and reduces the production cost.

[0027] In the embodiment, refer to Figure 1 The SiO2 protective layer 4 is in the range of 50-10000A (thickness unit, 1A=0.1 nanometer).

[0028] The oxide layer for passivation of the Fab is generally several thousand A, which falls within the range of 50-10000A.

[0029] Refer to Figure 4 It is shown as a bidirectional TVS tube. Figure 4

[0030] The working principle of the utility model is: taking the first conductivity type substrate 1 as an example, when the first metal electrode 5 is positive (at this time, the second metal electrode 6 is negative), the first second-conductivity-type well region 2 and the NSUB form a forward-biased PN junction, and the NSUB and the second second-conductivity-type well region 3 form a reverse-biased TVS tube; when the second metal electrode 6 is positive (at this time, the first metal electrode 5 is negative), the second second-conductivity-type well region 3 and the NSUB form a forward-biased PN junction, and the NSUB and the first second-conductivity-type well region 2 form a reverse-biased TVS tube. The protection capability is good when dealing with circuits that require different protection voltage values in the forward and reverse directions.

[0031] It is apparent for those skilled in the art that the utility model is not limited to the details of the above-mentioned exemplary embodiments, and the utility model can be realized in other specific forms without departing from the spirit or basic characteristics of the utility model. Therefore, from any point of view, the embodiments should be regarded as exemplary and non-limiting.

[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 properly combined to form other embodiments that can be understood by those skilled in the art.​

Claims

1. A lateral structure bidirectional asymmetric voltage surge protection device, characterized in that, The bidirectional asymmetric voltage surge protection device of the transverse structure comprises a wafer, a first conductive type substrate is arranged on the wafer, a plurality of first second conductive type well regions are arranged on a P+ region of the wafer, a plurality of second second conductive type well regions are arranged on a P++ region of the wafer, the first second conductive type well regions and the second second conductive type well regions are arranged alternately, a SiO2 protective layer is arranged on the surface of the wafer, a first metal electrode is connected to the first second conductive type well regions, and a second metal electrode is connected to the second second conductive type well regions.

2. The lateral-structure bidirectional asymmetric voltage surge protection device according to claim 1, wherein, The first conductive type substrate has a thickness of 100-400 um and a resistivity of 0.005-100 Ω*cm.

3. The lateral-structure bidirectional asymmetric voltage surge protection device of claim 1, wherein, The first second conductive type well regions have an impurity concentration of a1.

4. The lateral-structure bidirectional asymmetric voltage surge protection device of claim 1, wherein, The second second conductive type well regions have an impurity concentration of a2.

5. The lateral-structure bidirectional asymmetric voltage surge protection device according to any one of claims 1 to 4, wherein The SiO2 protective layer has a thickness of 50-10000 A.

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