Bidirectional ESD protection device

Abstract

The utility model relates to an ESD (Electro-Static Discharge) protection device, in particular to a bidirectional ESD protection device, which comprises a P-type substrate, P + expansion regions are arranged on the upper surface and the lower surface of the P-type substrate, and first N + expansion regions are arranged on the surfaces of the P + expansion regions and the P-type substrate; the positions of the first N + expansion regions on the upper surface and the lower surface of the P-type substrate are symmetrical; a second N + expansion region is arranged on the P + expansion region; oxidation layers are arranged on the P + expansion region and the second N + expansion region, a positive electrode metal layer is arranged at the top of the oxidation layer on the upper surface of the P-type substrate, and a negative electrode metal layer is arranged at the bottom of the oxidation layer on the lower surface of the P-type substrate; the lower surface of the positive electrode metal layer is in contact with the first N + expansion region, the P + expansion region and the second N + expansion region; and the upper surface of the negative electrode metal layer is in contact with the first N + expansion region, the P + expansion region and the second N + expansion region. According to the utility model, the surge protection capability can be effectively improved while miniaturized packaging is ensured.

Description

TECHNICAL FIELD

[0001] The utility model relates to ESD protection device, concretely relates to a kind of bidirectional ESD protection device. BACKGROUND

[0002] In the current continuous innovation of electronic technology, product iteration is changing day by day, miniaturization, high surge capacity has become the pursuit goal of protection products. In recent years, with the terminal product field constantly moving towards fine, miniaturization, especially with smart watch, wireless headset as the representative of wearing product is popular in the market, this trend is more obvious.

[0003] Wearing product is loved by consumers with its portable, fashionable characteristics, but this also puts higher requirements on internal protection components. Surge as a common electrical interference, may be caused by lightning, power grid fluctuation, once invading terminal product, it is easy to cause equipment damage.

[0004] However, limited by current process level, protection products usually can only use traditional ways such as increasing area and reducing thickness to improve surge protection capability. But increasing area will occupy more space, which is contrary to the demand of miniaturization of terminal product. Reducing thickness can optimize performance to a certain extent, but it may affect the mechanical strength and reliability of product. Therefore, how to effectively improve surge protection capability while ensuring miniaturization packaging has become a difficult problem to be solved in the industry. UTILITY MODEL CONTENT

[0005] The utility model aims at solving the technical problem that existing ESD protection device cannot effectively improve surge protection capability while ensuring miniaturization packaging, and provides a kind of bidirectional ESD protection device.

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

[0007] A kind of bidirectional ESD protection device, including P-type substrate, P-type substrate's upper and lower surfaces are all equipped with P+ extension area, P+ extension area and the surface of P-type substrate are equipped with first N+ extension area;The position of first N+ extension area on the upper and lower surfaces of P-type substrate is symmetrical;

[0008] Second N+ extension area is provided on the P+ extension area;

[0009] Oxidation layer is provided on P+ extension area and second N+ extension area, positive electrode metal layer is provided on the top of oxidation layer on the upper surface of P-type substrate, negative electrode metal layer is provided on the bottom of oxidation layer on the lower surface of P-type substrate;

[0010] The lower surface of positive electrode metal layer is in contact with first N+ extension area, P+ extension area and second N+ extension area;

[0011] The upper surface of the negative metal layer is in contact with the first N+ extension region, the P+ extension region and the second N+ extension region.

[0012] Further, the positive metal layer is a metal aluminum layer.

[0013] The negative metal layer comprises a metal aluminum layer with its upper surface connected to the bottom of the oxide layer on the lower surface of the P-type substrate, and a titanium-nickel-silver layer arranged on the lower surface of the metal aluminum layer.

[0014] Further, the thickness of the first N+ extension region is 15-40 um.

[0015] Further, the thickness of the P+ extension region is 2.5-5 um, and the doping concentration is 3e17-6e18.

[0016] Further, the thickness of the second N+ extension region is 1-3 um, and the doping concentration is greater than or equal to 1e18.

[0017] Further, the thickness of the positive metal layer and the negative metal layer is greater than 3 um.

[0018] Compared with the prior art, the utility model has the advantages of:

[0019] The bidirectional ESD protection device provided by the utility model forms a longitudinal NPN by arranging the first N+ extension regions symmetrically on the upper and lower surfaces of the P-type substrate, and the punch-through breakdown can be realized by adjusting the thickness of the first N+ extension region, so that the residual voltage of the surge is reduced, and the highest clamping voltage of the surge is limited; compared with the prior art, the area of the ESD protection device does not need to be increased or the thickness of the ESD protection device does not need to be reduced, so that the surge protection capability of the ESD protection device can be improved; moreover, the first N+ extension regions and the P+ extension regions on the upper and lower surfaces of the P-type substrate form low-voltage starting tubes D1 and D2 respectively, the protection of different working voltages can be realized by adjusting the threshold values of the low-voltage starting tubes D1 and D2, and the surge capability and the residual voltage are greatly improved. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 It is a structural schematic view of the utility model embodiment;

[0021] Figure 2 It is an equivalent circuit schematic view of the utility model embodiment;

[0022] Figure 3 It is a schematic view of the current discharge path in the utility model embodiment.

[0023] The reference signs are explained as follows: 1-P-type substrate, 2-P+ extension region, 3-first N+ extension region, 4-second N+ extension region, 5-oxide layer, 6-positive metal layer, 7-negative metal layer. DETAILED DESCRIPTION

[0024] The technical solutions of this utility model will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this utility model, and not all of them. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this utility model.

[0025] like Figure 1 As shown, a bidirectional ESD protection device includes a P-type substrate 1, on which P+ expansion regions 2 with a thickness of 2.5-5 μm are provided on both the upper and lower surfaces, and the doping concentration of the P+ expansion regions 2 is 3e17-6e18; a first N+ expansion region 3 with a thickness of 15-40 μm is provided on the surfaces of the P+ expansion regions 2 and the P-type substrate 1; the positions of the first N+ expansion regions 3 on the upper and lower surfaces of the P-type substrate 1 are symmetrical.

[0026] The P+ expansion region 2 is provided with a second N+ expansion region 4 with a thickness of 1 to 3 μm, and the doping concentration of the second N+ expansion region 4 is greater than or equal to 1e18.

[0027] An oxide layer 5 is provided on the P+ expansion region 2 and the second N+ expansion region 4. A positive electrode metal layer 6 is provided on the top of the oxide layer 5 on the upper surface of the P-type substrate 1, and a negative electrode metal layer 7 is provided on the bottom of the oxide layer 5 on the lower surface of the P-type substrate 1.

[0028] The thickness of the positive electrode metal layer 6 and the negative electrode metal layer 7 is greater than 3 μm;

[0029] The positive electrode metal layer 6 is an aluminum layer; the negative electrode metal layer 7 includes an aluminum layer whose upper surface is connected to the bottom of the oxide layer 5 on the lower surface of the P-type substrate 1, and a titanium-nickel-silver layer disposed on the lower surface of the aluminum layer.

[0030] The lower surface of the positive electrode metal layer 6 is in contact with the first N+ expansion region 3, the P+ expansion region 2, and the second N+ expansion region 4;

[0031] The upper surface of the negative electrode metal layer 7 is in contact with the first N+ expansion region 3, the P+ expansion region 2, and the second N+ expansion region 4.

[0032] like Figure 2 As shown, the equivalent circuit of the above-mentioned bidirectional ESD protection device consists of an NPN transistor, low-voltage turn-on transistors D1 and D2. The collector and emitter of the NPN transistor are connected to the two electrodes Pin1 and Pin2 of the protection transistor, respectively. The anodes of the low-voltage turn-on transistors D1 and D2 are connected to the base of the NPN transistor. The cathode of the low-voltage turn-on transistor D1 is connected to Pin1, and the cathode of the low-voltage turn-on transistor D2 is connected to Pin2.

[0033] like Figure 3As shown, low-voltage tube D1 and D2 are two shallow-junction ESD PN junction diodes on the front and back of the chip, respectively, for opening low-voltage tube D1 when a forward (top to bottom) surge, ESD or pulse voltage is applied, and after opening, the current flows through low-voltage tube D1 to D2. Due to the low dynamic impedance of the NPN tube, part of the current will flow into the base of the NPN tube. As the current increases, the NPN tube opens into a saturated amplification state, and a negative resistance phenomenon occurs between the two ends of the device, thereby increasing the surge discharge current and reducing the device residual voltage. For negative pulses, the principle is the same as above, except that the current is released from the bottom to the top.

[0034] As shown in the drawings, Figure 1 The preparation method of the bidirectional ESD protection device is specifically as follows.

[0035] 1) Dope N-type impurities on the P-type substrate 1 by double-sided injection or diffusion, and perform high-temperature annealing to form a first N+ extension region 3 with a thickness of 15-40 um, which constitutes a deep-junction NPN tube for realizing the negative resistance effect and large current release of the device;

[0036] The first N+ extension region 3 is located symmetrically on the upper and lower surfaces of the P-type substrate 1 and is aligned in the longitudinal structure;

[0037] 2) Form a P+ extension region 2 with a thickness of 2.5-5 um outside the first N+ extension region 3 by boron doping with a doping concentration of 3e17-6e18;

[0038] 3) Form a second N+ extension region 4 with a thickness of 1-3 um on the P+ extension region 2 by phosphorus or arsenic diffusion, with a doping concentration greater than or equal to 1e18;

[0039] The P+ extension region 2 and the second N+ extension region 4 form low-voltage tubes D1 and D2;

[0040] Meanwhile, a second N+ extension region 4 with a thickness of 1-3 um is also formed on the periphery of the first N+ extension region 3 by phosphorus or arsenic diffusion to form a guard ring for preventing device leakage;

[0041] 4) Etch the P+ extension region 2, the first N+ extension region 3 and the second N+ extension region 4 to form a contact hole, and set a positive metal layer 6 on the top of the oxide layer 5 on the upper surface of the P-type substrate 1 to form Pin1; set a negative metal layer 7 on the bottom of the oxide layer 5 on the lower surface of the P-type substrate 1 to form Pin2;

[0042] The positive metal layer 6 is a metal aluminum layer;

[0043] The negative metal layer 7 includes a metal aluminum layer and a titanium-nickel-silver layer arranged on the lower surface of the metal aluminum layer;

[0044] The thickness of the positive electrode metal layer 6 and the negative electrode metal layer 7 is greater than 3 um.

[0045] The above merely provides the specific implementation of the present application, but the protection scope of the present application is not limited to this. Any change or replacement within the technical scope disclosed by the present application should be covered in the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A bidirectional ESD protection device, characterized by: The application relates to a P-type substrate (1), P+ diffusion region (2) is arranged on the upper and lower surfaces of the P-type substrate (1), a first N+ diffusion region (3) is arranged on the surfaces of the P+ diffusion region (2) and the P-type substrate (1); the first N+ diffusion region (3) on the upper and lower surfaces of the P-type substrate (1) is positionally symmetrical; A second N+ diffusion region (4) is arranged on the P+ diffusion region (2); An oxide layer (5) is arranged on the P+ diffusion region (2) and the second N+ diffusion region (4); a positive electrode metal layer (6) is arranged on the top of the oxide layer (5) on the upper surface of the P-type substrate (1), and a negative electrode metal layer (7) is arranged on the bottom of the oxide layer (5) on the lower surface of the P-type substrate (1); The lower surface of the positive electrode metal layer (6) is in contact with the first N+ diffusion region (3), the P+ diffusion region (2) and the second N+ diffusion region (4); The upper surface of the negative electrode metal layer (7) is in contact with the first N+ diffusion region (3), the P+ diffusion region (2) and the second N+ diffusion region (4).

2. The bidirectional ESD protection device of claim 1, wherein, The positive electrode metal layer (6) is a metal aluminum layer; The negative electrode metal layer (7) comprises a metal aluminum layer connected with the bottom of the oxide layer (5) on the lower surface of the P-type substrate (1) and a titanium-nickel-silver layer arranged on the lower surface of the metal aluminum layer.

3. The bidirectional ESD protection device of claim 1, wherein, The thickness of the first N+ diffusion region (3) is 15-40 um.

4. The bidirectional ESD protection device of claim 1, wherein, The thickness of the positive electrode metal layer (6) and the negative electrode metal layer (7) is greater than 3 um.

Images