A etching process with a top layer of metallic nickel.

Abstract

A etching process for a top layer of metallic nickel. This invention uses a PBE etching solution and a novel etching process. The PBE etching solution primarily etches the nickel oxide layer on the Ni surface, followed by etching of pure Ni metal using a NiAg etching solution. The PBE etching solution composition is: glacial acetic acid (CH3COOH): nitric acid (HNO3): hydrofluoric acid (HF) = 3.7%: 2%: 8.9%. PBE can not only etch the oxide layer but also etch Ti; the underlying metallic Ti layer is also mainly etched by PBE. In the etching process, after 10 seconds of PBE etching, the surface nickel oxide is completely removed. Then, without rinsing, the surface is directly immersed in the NiAg etching solution to further etch the Ni surface. After rinsing, the underlying metallic Ti layer is then etched. This invention features simple processing, clean and efficient nickel oxide etching.

Description

Technical Field

[0001] This invention relates to semiconductor processing technology, and more particularly to an etching process for a top layer of metallic nickel. Background Technology

[0002] A planar Schottky barrier diode, also known as a barrier diode or simply a planar Schottky diode, is often represented as PSBD. It is a unipolar, majority-carrier device that operates by utilizing the contact barrier between a metal and a semiconductor. It features a small minority carrier injection effect, fast switching speed, low switching power loss, high frequency, and low forward voltage drop, among other characteristics.

[0003] Traditional PSBD products use TiNiAg as the front-side evaporation metal structure. With increasing product performance requirements, some products now use TiNi instead of TiNiAg. Extensive research has shown that replacing TiNiAg with TiNi can improve product performance and address some of the problems associated with TiNiAg during encapsulation. Therefore, TiNi is used instead of TiNiAg. However, Ni, as the top-layer metal, is easily oxidized and difficult to corrode, making the fabrication process of TiNi structure products a challenge. Summary of the Invention

[0004] To address the above problems, this invention provides a simple etching process that effectively removes nickel oxide and creates a top layer of metallic nickel.

[0005] The technical solution of this invention is: an etching process for a top layer of metallic nickel, comprising the following steps:

[0006] S100, an N- epitaxial layer is fabricated on an N+ substrate;

[0007] S200, a silicon dioxide layer is grown on the N-epitaxial layer;

[0008] S300 uses photolithography and etching processes to form a ring on a silicon dioxide layer, and then implants boron ions into the ring to form a semiconductor voltage-resistant ring;

[0009] In the S400 process, a semiconductor voltage-delay ring is wrapped around the oxide layer using photolithography and etching processes to open the dicing channel; phosphorus is injected into the dicing channel to form a stop ring before proceeding.

[0010] After the S500 is advanced, the active region is formed by photolithography and etching processes, and a layer of barrier metal is sputtered in the active region. After a high-temperature process, the barrier metal and silicon form silicide.

[0011] S600, remove excess barrier metal, evaporate the first metal layer on top of silicide, and then retain the first metal layer through photolithography and etching processes to form metal layer one;

[0012] S700, a passivation layer is applied above the first metal layer, and a second metal layer is evaporated on the passivation layer;

[0013] S800, photoresist is coated on the area to be retained on the second metal layer, and wet etching is used to etch the area not protected by the photoresist, retaining the required part, to form TiNi metal layer two;

[0014] In step S800, the wet etching step includes:

[0015] S810, first place the product obtained in step S800 into PBE etching solution to etch away the oxide on the surface, then place it into NiAg etching solution for 360 seconds to etch away the Ni on the surface.

[0016] S820, after completing step S810, take it out and rinse it with water to remove the residual NiAg acid on the surface;

[0017] S830 is then placed in the same PBE etching solution for etching to remove the Ti metal layer beneath Ni.

[0018] S840, after completing step S830, take it out and rinse it with water to clean the surface of the acid.

[0019] S850, spin dry to complete the entire operation process.

[0020] Specifically, the PBE etching solution includes glacial acetic acid, nitric acid, and hydrofluoric acid.

[0021] Specifically, the PBE etching solution is prepared in the following proportions:

[0022] Glacial acetic acid (CH3COOH): Nitric acid (HNO3): Hydrofluoric acid (HF) = 3.7%: 2%: 8.9%.

[0023] This invention utilizes a PBE etching solution and a novel etching process. The PBE etching solution primarily etches the nickel oxide layer on the Ni surface, followed by etching of pure Ni metal with a NiAg etching solution. The PBE etching solution composition is: glacial acetic acid (CH3COOH): nitric acid (HNO3): hydrofluoric acid (HF) = 3.7%: 2%: 8.9%. PBE not only etches the oxide layer but also corrodes Ti; the underlying Ti metal is also primarily etched by PBE. In the etching process, after 10 seconds of PBE etching, the surface nickel oxide is completely removed. Then, without rinsing, the surface is directly immersed in the NiAg etching solution to further remove the Ni surface. After rinsing, the process continues with etching the underlying Ti metal. This invention features simple processing, efficient and thorough nickel oxide etching, and other advantages. Attached Figure Description

[0024] Figure 1 This is a structural schematic diagram of step S200 of the present invention.

[0025] Figure 2 This is a schematic diagram of the structure in step S300 when photolithography is used on the silicon dioxide layer.

[0026] Figure 3 This is a schematic diagram of the structure formed by etching in step S300.

[0027] Figure 4 This is a schematic diagram of the structure during step S300, when boron ions are implanted into the ring.

[0028] Figure 5 This is step S400, a schematic diagram of the structure when photoresist is used to encapsulate the semiconductor voltage withstand ring in the photolithography process.

[0029] Figure 6 This is a schematic diagram of the structure when the dicing channel is opened in step S400 of the etching process.

[0030] Figure 7 This is a schematic diagram of the structure during step S400, where phosphorus is injected into the dicing channel to form a stop ring.

[0031] Figure 8 yes Figure 7 A schematic diagram of the structure after removing the photoresist following the steps.

[0032] Figure 9 yes Figure 8 After the steps are completed, the schematic diagram shows the structure after the stop ring and withstand ring are pushed forward to form a silicon dioxide layer.

[0033] Figure 10 This is a schematic diagram of the structure after removing the excess silica layer.

[0034] Figure 11 This is a schematic diagram of the structure of the present invention. Detailed Implementation

[0035] Embodiments of the present invention are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0036] In existing technologies, nickel-silver etching solutions can etch both nickel and silver simultaneously, but nickel with a single-layer structure is difficult to etch. When evaporated metallic nickel comes into contact with air, it oxidizes into nickel oxide, which conventional NiAg etching solutions cannot completely etch.

[0037] NiAg etching solution ratio: glacial acetic acid (CH3COOH): nitric acid (HNO3): water (H2O) = 65%: 20%: 15%

[0038] The chemical equation for the reaction between Ni and nickel is: Ni + 4HNO3 = Ni(NO3)2 + 2NO2 + 2H2O

[0039] Titanium-nickel is a novel metallic structure. Nickel metal is easily oxidized and difficult to corrode after oxidation. When nickel is used as the top layer metal, nickel oxide is difficult to completely etch away using nickel-silver etching solution, and the etching time is too long, leading to photoresist detachment and corrosion. Product requirements necessitate using a Ni layer as the top layer metal. This project employs a novel etching process to completely etch away the nickel oxide.

[0040] An etching process for a top layer of metallic nickel includes the following steps:

[0041] S100, an N- epitaxial layer is fabricated on an N+ substrate;

[0042] S200, a silicon dioxide layer is grown on the N-epitaxial layer; reference Figure 1 As shown;

[0043] S300 uses photolithography and etching processes to form a ring on a silicon dioxide layer, and then implants boron ions into the ring to form a semiconductor voltage-resistant ring (P). + ); reference Figures 2-4 As shown;

[0044] In the S400 process, a semiconductor voltage-delay ring is encapsulated on the oxide layer using photolithography and etching processes, opening the dicing channel; phosphorus is implanted into the dicing channel to form a stop ring (N). + ), and then proceed; refer to Figures 5-8 As shown;

[0045] Figure 9 For: in Figure 8 A silicon dioxide layer is then prepared on top of the original silicon dioxide layer, and the structural diagram is shown after the layer is combined with the original silicon dioxide layer.

[0046] Figure 10 For: in Figure 9 Based on this, a schematic diagram of the structure after removing the excess silicon dioxide layer is shown;

[0047] After the S500 is advanced, the active region is formed by photolithography and etching processes, and a layer of barrier metal is sputtered in the active region. After a high-temperature process, the barrier metal and silicon form silicide.

[0048] S600, remove excess barrier metal, evaporate the first metal layer above the silicon dioxide layer and the barrier metal region, and then retain the first metal layer above through photolithography and etching processes to form metal layer one;

[0049] S700, a passivation layer is applied above the first metal layer, and a second metal layer is evaporated on the passivation layer;

[0050] S800, photoresist is coated on the area to be retained on the second metal layer, and wet etching is used to etch the area not protected by the photoresist, retaining the required part, to form TiNi metal layer two;

[0051] In step S800, the wet etching step includes:

[0052] S810, first place the product obtained in step S800 into PBE etching solution for 10 seconds to etch away the oxides on the surface (the oxides formed when Ni metal evaporates and comes into contact with oxygen). After etching, do not rinse with water, place it into NiAg etching solution for 360 seconds to etch away the Ni on the surface.

[0053] S820, after completing step S810, take it out and rinse it with water to remove the residual NiAg acid on the surface;

[0054] S830, then put it into the same PBE etching solution for 10 seconds to etch away the Ti metal under Ni;

[0055] S840, after completing step S830, take it out and rinse it with water to clean the surface of the acid.

[0056] S850, spin dry to complete the entire operation process.

[0057] The PBE etching solution includes glacial acetic acid (CH3COOH), nitric acid (HNO3), and hydrofluoric acid (HF).

[0058] The PBE etching solution is prepared in the following proportions:

[0059] Glacial acetic acid (CH3COOH): Nitric acid (HNO3): Hydrofluoric acid (HF) = 3.7%: 2%: 8.9%.

[0060] To further improve the technical effectiveness of this case, the time combination of PBE etchant and NiAg etchant was further studied, and the analysis is as follows:

[0061]

[0062] In microscopic photographs, if there is metal residue on the passivation layer, resulting in a dark color, and the underlying metal color is not visible, the sample is considered defective. If there is no metal residue on the scribe line and the passivation layer, the sample is considered acceptable.

[0063] The titanium-nickel metal structure was processed using PBE etchant and a new etching process. The PBE etchant primarily etches the nickel oxide on the Ni surface, followed by NiAg etchant to etch pure Ni metal. The PBE etchant composition is: glacial acetic acid (CH3COOH): nitric acid (HNO3): hydrofluoric acid (HF) = 3.7%: 2%: 8.9%. The chemical equation for the reaction with nickel oxide is: NiO + 2H+ = Ni2++H2O

[0064] PBE can corrode not only the oxide layer but also Ti. The underlying metallic Ti is mainly corroded by PBE. The chemical equation for the reaction between PBE and Ti is: Ti + 5HF = H2TiF6 + 2H2

[0065] Corrosion process: After PBE etching for 10 seconds, the surface nickel oxide is etched away. Then, without rinsing, it is directly immersed in NiAg etching solution to etch away the surface Ni. After rinsing, the underlying metal Ti is then etched.

[0066] Note: PBE etching for 10 seconds can effectively remove nickel oxide from the surface. The nickel can be further immersed in the acid bath without rinsing, primarily to prevent Ni from re-oxidizing and becoming difficult to etch. This etching process effectively removes the nickel.

[0067] Regarding the information disclosed in this case, the following points need to be clarified:

[0068] (1) The accompanying drawings of the embodiments disclosed in this case only involve the structures involved in the embodiments disclosed in this case. Other structures can refer to the general design.

[0069] (2) Where there is no conflict, the embodiments and features disclosed in this case can be combined with each other to obtain new embodiments;

[0070] The above are merely specific embodiments disclosed in this case, but the scope of protection of this disclosure is not limited thereto. The scope of protection disclosed in this case shall be determined by the scope of protection of the claims.

Claims

1. An etching process for a top layer of metallic nickel, characterized in that, Includes the following steps: S100, an N- epitaxial layer is fabricated on an N+ substrate; S200, a silicon dioxide layer is grown on the N-epitaxial layer; S300 uses photolithography and etching processes to form a ring on a silicon dioxide layer, and then implants boron ions into the ring to form a semiconductor voltage-resistant ring; In the S400 process, a semiconductor voltage-delay ring is wrapped around the oxide layer using photolithography and etching processes to open the dicing channel; phosphorus is injected into the dicing channel to form a stop ring before proceeding. After the S500 is advanced, the active region is formed by photolithography and etching processes, and a layer of barrier metal is sputtered in the active region. After a high-temperature process, the barrier metal and silicon form silicide. S600, remove excess barrier metal, evaporate the first metal layer on top of silicide, and then retain the first metal layer through photolithography and etching processes to form metal layer one; S700, a passivation layer is applied above the first metal layer, and a second metal layer is evaporated on the passivation layer; S800, photoresist is coated on the area to be retained on the second metal layer, and wet etching is used to etch the area not protected by the photoresist, retaining the required part, to form TiNi metal layer two; In step S800, the wet etching step includes: S810, first place the product obtained in step S800 into PBE etching solution to etch away the oxide on the surface, then place it into NiAg etching solution for 360 seconds to etch away the Ni on the surface. S820, after completing step S810, take it out and rinse it with water to remove the residual NiAg acid on the surface; S830 is then placed in the same PBE etching solution for etching to remove the Ti metal layer beneath Ni. S840, after completing step S830, take it out and rinse it with water to clean the surface of the acid. S850, spin-drying completes the entire operation process; The PBE etching solution includes glacial acetic acid, nitric acid, and hydrofluoric acid; The PBE etching solution was prepared in the following proportions: glacial acetic acid: nitric acid: hydrofluoric acid = 3.7%: 2%: 8.9%; In the corrosion process, after PBE corrosion for 10 seconds, the surface nickel oxide is removed. Then, without rinsing, the surface is directly immersed in NiAg corrosion solution to remove the surface Ni. After rinsing, the underlying metal Ti is then etched.

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