SCR device structure for ESD protection

Abstract

The utility model relates to an SCR (Selective Catalytic Reduction) device structure, in particular to an SCR device structure for ESD (Electro-Static Discharge) protection, which comprises a P-type substrate layer, an N-type trap and two P-type traps are arranged on the P-type substrate layer, and the tops of the N-type trap and the two P-type traps are connected with the bottom of an isolating layer; the two P-type wells are distributed on two sides of the N-type well and are connected with the N-type well; two P-type active regions of which the tops are connected with the bottom of the isolation layer are arranged on the N-type well; an N-type active region of which the top is connected with the bottom of the isolation layer is arranged on the P-type well; an anode metal layer and a cathode metal layer are arranged at the top of the isolation layer; the bottom of the anode metal layer penetrates through the isolation layer and is connected with the two P-type active regions and the N-type well; the bottom of the cathode metal layer passes through the isolation layer and is connected with the P-type active region. According to the utility model, the Schottky contact formed by directly connecting the anode metal layer and the N-type well is introduced to replace the conventional ohmic contact, and because the Schottky contact has a lower capacitance value, the SCR device structure can realize a lower capacitance value, so that the SCR device structure can be suitable for high-frequency and high-speed application occasions.

Description

Technical Field

[0001] The utility model relates to the structure of an SCR device, and particularly to an SCR device structure for ESD protection. Background Art

[0002] With the rapid development of semiconductor technology, especially the continuous progress of integrated circuit (IC) technology, the functions of electronic products are becoming increasingly powerful. At the same time, higher requirements are put forward for electrostatic discharge (ESD) protection. ESD is a phenomenon that electronic devices often encounter in the working environment, and its transient high voltage may seriously damage or even destroy electronic devices. Therefore, it is particularly important to develop efficient and reliable ESD protection devices.

[0003] In the field of ESD protection, the silicon controlled rectifier (SCR) stands out due to its unique advantages. The SCR device plays an important role in the protection circuit with its strong surge current withstand ability and relatively low holding voltage. In traditional designs, the SCR integrates multiple protection functions within a single device through integration with the forward structure, which not only simplifies the circuit design but also reduces the manufacturing cost.

[0004] However, this integration method also brings non-negligible limitations. The close integration of the SCR and the forward structure leads to a strong mutual influence between the two, making it extremely difficult to precisely adjust the working voltage of the SCR. In addition, limited by the integration structure and material properties, traditional SCR structures often struggle to achieve lower capacitance values, which is particularly disadvantageous in high-frequency and high-speed applications. Summary of the Utility Model

[0005] The purpose of the utility model is to solve the technical problem that traditional SCR structures are difficult to achieve lower capacitance values, and to provide an SCR device structure for ESD protection.

[0006] To solve the above technical problems, the technical solution provided by the utility model is as follows:

[0007] An SCR device structure for ESD protection includes a P-type substrate layer and an isolation layer provided on top of it;

[0008] An N-type well and two P-type wells are provided on the P-type substrate layer, with the top of the N-type well connected to the bottom of the isolation layer, and the two P-type wells are distributed on both sides of the N-type well and connected to it;

[0009] Two P-type active regions with their tops connected to the bottom of the isolation layer are provided on the N-type well;

[0010] An N-type active region with its top connected to the bottom of the isolation layer is provided on the P-type well;

[0011] The top of the isolation layer is provided with an anode metal layer and a cathode metal layer. The bottom of the anode metal layer passes through the isolation layer and is connected to two P-type active regions and an N-type well; the bottom of the cathode metal layer passes through the isolation layer and is connected to the P-type active region.

[0012] Furthermore, lead holes corresponding to the N-type active region, P-type active region, and N-type well are formed in the isolation layer;

[0013] The bottom of the anode metal layer is connected to two P-type active regions and an N-type well through the lead holes corresponding to the P-type active region and the N-type well and passing through the isolation layer;

[0014] The bottom of the cathode metal layer is connected to the P-type active region through the lead hole corresponding to the N-type active region and passing through the isolation layer.

[0015] Furthermore, the material of the P-type substrate layer is silicon with a <100> crystal orientation, and its resistivity is greater than 20 Ω·cm.

[0016] Furthermore, the doping material of the P-type well is boron, and the doping material of the N-type well is phosphorus.

[0017] Furthermore, the doping material of the N-type active region is arsenic, and the doping material of the P-type active region is boron.

[0018] Furthermore, the material of the isolation layer is borophosphosilicate glass.

[0019] Furthermore, the materials of the anode metal layer and the cathode metal layer are aluminum-silicon alloy, and the thickness of the aluminum-silicon alloy is 1.2 - 2 μm.

[0020] Compared with the prior art, the beneficial effects of the present utility model are as follows:

[0021] The SCR device structure for ESD protection provided by the present utility model forms a Schottky contact by introducing the direct connection between the anode metal layer and the N-type well to replace the conventional Ohmic contact. Since the Schottky contact has a lower capacitance value, the SCR device structure can achieve a lower capacitance value, enabling it to be applicable to high-frequency and high-speed application scenarios; moreover, by adjusting the contact area between the anode metal layer and the N-type well, the holding voltage and holding current of the SCR device structure can be further adjusted, thereby optimizing the overall performance of the device to meet the requirements of different application scenarios. Description of the Drawings

[0022] Figure 1 It is a schematic structural diagram of an embodiment of the present utility model.

[0023] Description of the reference numerals: 1 is the P-type substrate layer, 2 is the isolation layer, 3 is the N-type well, 4 is the P-type well, 5 is the P-type active region, 6 is the N-type active region, 7 is the anode metal layer, and 8 is the cathode metal layer. Detailed Embodiment

[0024] The technical solutions in the present utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present utility model, rather than all embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present utility model without creative efforts shall fall within the protection scope of the present utility model.

[0025] As Figure 1 shown, a SCR device structure for ESD protection includes a P-type substrate layer 1 and an isolation layer 2 provided on top of it; an N-type well 3 and two P-type wells 4 are provided on the P-type substrate layer 1, with the top of the N-type well 3 connected to the bottom of the isolation layer 2; the two P-type wells 4 are distributed on both sides of the N-type well 3 and connected to it.

[0026] Two P-type active regions 5 with their tops connected to the bottom of the isolation layer 2 are provided on the N-type well 3; an N-type active region 6 with its top connected to the bottom of the isolation layer 2 is provided on the P-type well 4.

[0027] An anode metal layer 7 and a cathode metal layer 8 are provided on the top of the isolation layer 2, and lead holes corresponding to the N-type active region 6, P-type active region 5, and N-type well 3 are formed on the isolation layer 2; the bottom of the anode metal layer 7 is connected to the two P-type active regions 5 and the N-type well 3 through the lead holes corresponding to the P-type active region 5 and the N-type well 3 passing through the isolation layer 2; the bottom of the cathode metal layer 8 is connected to the P-type active region 5 through the lead hole corresponding to the N-type active region 6 passing through the isolation layer 2.

[0028] In this embodiment, the materials of the various parts in the SCR device structure are as follows:

[0029] The material of the P-type substrate layer 1 is silicon with a <100> crystal orientation and a resistivity greater than 20 Ω·cm.

[0030] The doping material of the P-type well 4 is boron, with an implantation energy of 70 - 90 kev and a dose of 6e12 - 3e13; the doping material of the N-type well 3 is phosphorus, with an implantation energy of 100 - 120 kev and a dose of 1e13 - 3e13; the formation temperature of the N-type well 3 and the P-type well 4 is 1150 °C, and the time is 1.5 h - 2 h.

[0031] The doping material of the N-type active region 6 is arsenic, with an implantation energy of 80 kev and a dose of 5 - 7e15; the doping material of the P-type active region 5 is boron, with an implantation energy of 25 - 40 kev and a dose of 2 - 4e15.

[0032] The material of the isolation layer 2 is borophosphosilicate glass, deposited at 15 K.

[0033] The materials of the anode metal layer 7 and the cathode metal layer 8 are aluminum-silicon alloy, and the thickness of the aluminum-silicon alloy is 1.2 - 2 μm.

[0034] The SCR device structure for ESD protection provided by the present utility model specifically has the following manufacturing steps:

[0035] 1) Use photo, implant, and drive-in processes to form a P-type well 4 and an N-type well 3 on the P-type substrate layer 1;

[0036] 2) Use photo and implant processes to form an N-type active region 6 on the P-type well 4 and form two P-type active regions 5 on the N-type well 3;

[0037] 3) Through an etching process, etch lead holes corresponding to the N-type active region 6, P-type active regions 5, and N-type well 3 on the isolation layer 2;

[0038] 4) Lead the bottom of the anode metal layer 7 through the lead holes corresponding to the P-type active regions 5 and N-type well 3 to pass through the isolation layer 2 and connect to the two P-type active regions 5 and N-type well 3 as the Anode lead (anode) of the SCR device structure;

[0039] Lead the bottom of the cathode metal layer 8 through the lead hole corresponding to the N-type active region 6 to pass through the isolation layer 2 and connect to the P-type active region 5 as the Cathode lead (cathode) of the SCR device structure.

[0040] The capacitance of the SCR device structure for ESD protection provided by the present utility model is mainly composed of three parts in series, where:

[0041] The first part is: the diode capacitance formed by the N-type well 3 and the P-type active region 5, and the Schottky diode capacitance formed by the anode metal layer 7 and the N-type well 3, and the two are in parallel to form the first capacitance;

[0042] The second part is: the first diode capacitance formed by the N-type well 3 and the P-type well 4;

[0043] The third part is: the second diode capacitance formed by the P-type well 4 and the N-type active region 6;

[0044] Since the capacitance in series makes the final capacitance value smaller than the capacitance value of any one of the series parts, the SCR device structure provided in this embodiment is easier to achieve a lower capacitance value.

[0045] The above is only the specific implementation manner of the present utility model, but the protection scope of the present utility model is not limited thereto. Any changes or substitutions within the technical scope disclosed by the present utility model should be covered within the protection scope of the present utility model. Therefore, the protection scope of the present utility model should be subject to the protection scope of the claims.

Claims

1. An SCR device structure for ESD protection, characterized in that: It includes a P-type substrate layer (1) and an isolation layer (2) disposed on top of it; An N-type well (3) and two P-type wells (4) with their tops connected to the bottom of the isolation layer (2) are provided on the P-type substrate layer (1); the two P-type wells (4) are distributed on both sides of the N-type well (3) and are connected to it; Two P-type active regions (5) with their tops connected to the bottom of the isolation layer (2) are provided on the N-type well (3); An N-type active region (6) with its top connected to the bottom of the isolation layer (2) is provided on the P-type well (4); An anode metal layer (7) and a cathode metal layer (8) are provided on the top of the isolation layer (2). The bottom of the anode metal layer (7) passes through the isolation layer (2) and is connected to the two P-type active regions (5) and the N-type well (3); the bottom of the cathode metal layer (8) passes through the isolation layer (2) and is connected to the P-type active region (5).

2. The SCR device structure for ESD protection according to claim 1, wherein: Via holes corresponding to the N-type active region (6), P-type active region (5) and N-type well (3) are formed on the isolation layer (2); The bottom of the anode metal layer (7) is connected to the two P-type active regions (5) and the N-type well (3) through via holes corresponding to the P-type active region (5) and the N-type well (3) and passing through the isolation layer (2); The bottom of the cathode metal layer (8) is connected to the P-type active region (5) through a via hole corresponding to the N-type active region (6) and passing through the isolation layer (2).

3. The SCR device structure for ESD protection according to claim 1, wherein: The material of the P-type substrate layer (1) is silicon with a <100> crystal orientation and its resistivity is greater than 20 Ω·cm.

4. The SCR device structure for ESD protection according to claim 1, characterized in that: The material of the P-type well (4) is boron, and the doping material of the N-type well (3) is phosphorus.

5. The SCR device structure for ESD protection according to claim 1, wherein: The doping material of the N-type active region (6) is arsenic, and the doping material of the P-type active region (5) is boron.

6. The SCR device structure for ESD protection according to claim 1, characterized in that: The material of the isolation layer (2) is borophosphosilicate glass.

7. The SCR device structure for ESD protection according to claim 1, characterized in that: The materials of the anode metal layer (7) and the cathode metal layer (8) are aluminum-silicon alloy, and their thickness is 1.2 - 2 μm.

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