Metal corrosion method and system

Abstract

The invention provides a metal corrosion method and system, and belongs to the technical field of semiconductors. The metal corrosion method comprises the following steps: forming a laser-induced periodic surface structure (LIPSS) on the surface of a metal thin film, and forming a metal thin film on the surface of the metal thin film, wherein the laser-induced periodic surface structure (LIPSS) is formed on the surface of the metal thin film; constructing a micro-fluidic channel on the surface of the metal film, wherein the micro-fluidic channel is communicated with an area where the laser-induced periodic surface structure is located; and corrosive liquid is conveyed to the area where the laser-induced periodic surface structure is located through a micro-fluidic channel for corrosion, so that a nano-structure is formed on the surface of the metal film. The metal corrosion precision can be improved.

Description

Technical Field

[0001] This disclosure belongs to the field of semiconductor technology, and specifically relates to a metal etching method and system. Background Technology

[0002] With the rapid development of integrated optoelectronic technology, the size of optoelectronic devices is constantly moving towards the micro-nano scale, placing extremely high demands on the precision, efficiency, and reliability of manufacturing processes. Metal etching, as a key step in the manufacturing of integrated optoelectronic devices, is widely used in electrode fabrication, metal interconnect structure formation, and device patterning.

[0003] Among related technologies, wet chemical etching is a common technique in metal etching, frequently used in semiconductor chip fabrication. Wet chemical etching involves placing a substrate device with a metal thin film deposited on its surface in an etching solution. By controlling the reaction environment temperature to optimize the chemical reaction kinetics at the solid-liquid interface, selective oxidation, complexation, or dissolution reactions occur between the metal thin film and the etching solution. This achieves precise removal and patterned etching of the metal thin film, ultimately obtaining metal structural units that meet device design requirements.

[0004] However, since wet chemical etching relies on the selectivity of the etchant for different materials, corrosion is essentially isotropic for the same material, meaning the corrosion rate is equal in all directions (longitudinal and transverse). Taking a typical metal / dielectric layer etching scenario as an example, if the metal layer (such as aluminum (Al) needs to be etched without damaging the underlying silicon dioxide (SiO2) dielectric layer, an etchant that reacts quickly with Al and slowly with SiO2 must be selected. However, at the micro- and nano-scale, minute differences in temperature, concentration, and stirring flow rate on the wafer surface can lead to subtle differences in the corrosion rate across different regions of the Al film, meaning the etching of the entire Al film is not completed simultaneously. Some areas may have been completely etched away, exposing the underlying SiO2; while other areas may still have residual aluminum film, making this technology significantly limited. Summary of the Invention

[0005] This disclosure provides a metal corrosion method and system that can improve the corrosion precision of metals. The technical solution is as follows:

[0006] This disclosure provides a metal corrosion method, which includes: forming a laser-induced periodic surface structure on the surface of a metal thin film; constructing a microfluidic channel on the surface of the metal thin film, the microfluidic channel being connected to the region where the laser-induced periodic surface structure is located; and delivering an etching solution to the region where the laser-induced periodic surface structure is located through the microfluidic channel to perform corrosion, thereby forming a nanostructure on the surface of the metal thin film.

[0007] In another implementation of this disclosure, the surface of the metal thin film is scanned using a femtosecond laser, and the spatial period of the laser-induced periodic surface structure is 0.8-1.2 times the wavelength of the femtosecond laser.

[0008] In yet another implementation of this disclosure, the depth of the laser-induced periodic surface structure satisfies the following formula:

[0009] d=k(E p / F th )ln(F0 / F th );

[0010] Where d is the depth of the laser-induced periodic surface structure; k is a material constant; E p The energy carried by each laser pulse; F0 is the laser flux; F th Threshold flux

[0011] In another implementation of this disclosure, the microfluidic channel includes a main channel and multiple branch channels; one end of the main channel is connected to an external fluid input device; each branch channel is connected to the main channel, and each branch channel has at least one serpentine mixing zone.

[0012] In another implementation of this disclosure, the step of constructing a microfluidic channel on the surface of the metal thin film includes: bonding a microfluidic chip having the microfluidic channel to the metal thin film having the laser-induced periodic surface structure, such that the microfluidic channel covers the area where the laser-induced periodic surface structure is located.

[0013] In another implementation of this disclosure, the microfluidic channel chip is a structural component with polydimethylsiloxane as the substrate material; the surface molecules of the inner wall of the microfluidic channel are modified with hydrophilic functional groups.

[0014] In another implementation of this disclosure, the hydrophilic functional group is modified on the inner wall of the microfluidic channel by surface grafting, and the hydrophilic functional group is any one of carboxyl, hydroxyl, sulfonic acid and amino groups.

[0015] In another implementation of this disclosure, the corrosive liquid includes nanocapsules containing a corrosive agent, a transport liquid for transporting the nanocapsules, and a pH adjusting liquid; wherein the nanocapsules are pH-responsive nanocapsules.

[0016] In another implementation of this disclosure, the step of delivering an etchant to the region where the laser-induced periodic surface structure is located through the microfluidic channel for etching includes: dynamically adjusting the concentration of the pH-adjusting liquid in the microfluidic channel so that the etching rate ratio of the metal film to the substrate material on which the metal film is deposited is between 1:0.2 and 1:5.

[0017] On the other hand, this disclosure provides a metal corrosion system applicable to the metal corrosion method described above. The metal corrosion system includes a laser processing module, a microfluidic channel module, and a corrosion control module. The laser processing module is used to form a laser-induced periodic surface structure on the surface of a metal thin film. The microfluidic channel module is used to construct a microfluidic channel on the surface of the metal thin film, and the microfluidic channel is connected to the region where the laser-induced periodic surface structure is located. The corrosion control module is used to deliver an etching solution to the region where the laser-induced periodic surface structure is located through the microfluidic channel for etching, thereby forming a nanostructure on the surface of the metal thin film.

[0018] The beneficial effects of the technical solutions provided in this disclosure are:

[0019] When etching a metal thin film in a device using the metal etching method provided in this disclosure, the method first forms laser-induced periodic surface structures (LIPSS) on the surface of the metal thin film. This causes lattice distortion in the LIPSS region, increasing the defect density and creating "active sites" for subsequent etching. Next, the method constructs microfluidic channels on the metal thin film surface, connecting these channels to the region containing the laser-induced periodic surface structures. Then, etching solution is delivered to the region containing the laser-induced periodic surface structures through the microfluidic channels to form nanostructures on the metal thin film surface. This allows the etching solution to be delivered to the LIPSS region via the microfluidic channels. Due to the presence of LIPSS, the metal thin film exhibits convex peaks and concave troughs, with atoms in the peaks and troughs having different energy states. Therefore, the etchant delivered through the microfluidic channel will perform anisotropic etching along the LIPSS structure, thereby enhancing the LIPSS and ultimately achieving etching only the metal film in the region where the LIPSS is located, without damaging the substrate material or non-etched areas where the metal film is located, thus greatly improving accuracy.

[0020] In other words, the method provided in this disclosure obtains LIPSS by treating the surface of a metal thin film, and then controls the flow area of ​​the etching liquid through microfluidic channels to improve the etching accuracy and make up for the shortcomings of traditional wet etching at the micro-nano scale, namely "poor selectivity and low precision". Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the embodiments of this disclosure, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this disclosure. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 This is a flowchart of a metal corrosion method provided in an embodiment of this disclosure;

[0023] Figure 2 This is a flowchart of another metal corrosion method provided in the embodiments of this disclosure;

[0024] Figure 3 This is a structural block diagram of the metal corrosion system provided in the embodiments of this disclosure. Detailed Implementation

[0025] To make the objectives, technical solutions, and advantages of this disclosure clearer, the embodiments of this disclosure will be described in further detail below with reference to the accompanying drawings.

[0026] This disclosure provides a method for metal corrosion, such as... Figure 1 As shown, metal corrosion methods include:

[0027] S101: Forming LIPSS on the surface of a metal thin film.

[0028] S102: Construct microfluidic channels on the surface of a metal thin film, with the microfluidic channels connected to the region where the LIPSS is located.

[0029] S103: Etching is performed by delivering etchant to the area where the LIPSS is located through microfluidic channels to form nanostructures on the surface of the metal thin film.

[0030] When etching a metal thin film in a device using the metal etching method provided in this disclosure, the method first forms a laser-induced periodic surface structure on the metal thin film surface. This creates a periodic nanostructure on the surface of the metal thin film, causing lattice distortion in the region where the LIPSS (Laser-Induced Periodic Surface Structure) is located, increasing the defect density and creating "active sites" for subsequent etching. Next, the method constructs microfluidic channels on the metal thin film surface, connecting these channels to the region where the laser-induced periodic surface structure is located. Then, etchant is delivered to the region through the microfluidic channels to etch the metal thin film, forming a nanostructure on the surface. This allows the etchant to be delivered to the region where the LIPSS is located via the microfluidic channels. Due to the presence of the LIPSS, the metal thin film exhibits convex peaks and concave troughs, with atoms in the peaks and troughs having different energy states. Therefore, the etchant delivered through the microfluidic channels performs anisotropic etching along the LIPSS structure, thereby enhancing the LIPSS. Ultimately, this achieves etching only the region where the LIPSS is located, without damaging the substrate or non-etched areas, significantly improving accuracy.

[0031] In other words, the method provided in this disclosure improves the corrosion precision by forming LIPSS on the surface of a metal thin film and then controlling the flow area of ​​the etchant through microfluidic channels, thus overcoming the shortcomings of traditional wet etching at the micro-nano scale, which is characterized by "poor selectivity and low precision".

[0032] On the other hand, embodiments of this disclosure also provide another metal corrosion method, such as Figure 2 As shown, the metal corrosion method includes:

[0033] S201: Provide a substrate and clean the substrate and deposit a dielectric layer.

[0034] In this embodiment of the disclosure, the substrate may be a silicon substrate.

[0035] The substrate is cleaned according to the standard cleaning procedure of RCA (Radio Corporation of America, whose technical team developed this cleaning process in 1965).

[0036] The dielectric layer was deposited using plasma-enhanced chemical vapor deposition (PECVD) with the following process parameters: SiH4 / N2O gas flow rate of 30 / 90 sccm (standard cubic centimeters per minute), RF power of 50 W (watts), and chamber pressure of 200 mTorr (millitors). The resulting SiO2 dielectric layer had a thickness of 500 ± 5 nm and a refractive index of 1.46 ± 0.01 measured at a wavelength of 633 nm (typically the wavelength of a helium-neon laser).

[0037] In other examples, the substrate can also be made of other materials. For example, the substrate structure of a GaN HEMT device (including a sapphire substrate, a GaN epitaxial layer, and a SiNx or Al2O3 dielectric layer).

[0038] S202: Deposit a thin metal film on a substrate.

[0039] In this embodiment of the disclosure, an electron beam evaporation system is used to deposit a metal thin film.

[0040] The metal thin film can be a gold thin film. The background vacuum level is less than 5 × 10⁻⁶. -6 Torr, deposition rate of 0.3 nm / s; first deposit a 5 nm thick Cr adhesion layer, then deposit a 200 nm thick Au conductive layer; the sheet resistance of the metal film is 0.25 ± 0.02 Ω / □ (ohms / square, representing the resistance between two opposite sides of a square film), and the surface roughness Ra ≤ 0.8 nm.

[0041] S203: The surface of a metal thin film is scanned using a femtosecond laser beam to induce the formation of LIPSS.

[0042] Optionally, step S203 includes the following steps:

[0043] The surface of the metal thin film is scanned using a femtosecond laser, and the spatial period Λ of the LIPSS is 0.8-1.2 times the wavelength of the femtosecond laser.

[0044] In LIPSS, the spatial period Λ refers to the spacing of the periodic stripes formed on the metal surface after laser scanning. By defining the above relationship, LIPSS can be made into a highly regular periodic structure.

[0045] Optionally, the depth of the LIPSS structure satisfies the following formula:

[0046] d=k(E p / F th )ln(F0 / F th (1)

[0047] Where d is the depth of the LIPSS structure, also known as the single-pulse ablation depth (in nanometers or micrometers); k is a material constant, also known as an empirical coefficient (usually between 0.1 and 0.3); E p The energy carried by each laser pulse; F0 is the laser flux; F th This represents the threshold flux.

[0048] Here, k encompasses all factors that are not explicitly expressed in the formula, such as: the thermal diffusivity of the material, the laser beam quality (M... 2 The efficiency of a material converting laser energy into heat energy (e.g., the efficiency of the material converting laser energy into heat energy) is a factor. k is a parameter that needs to be fitted experimentally, and the value of k varies for different materials and different laser systems.

[0049] E p This refers to the energy of a single pulse (measured in millijoules (mJ) or microjoules (μJ)). This is the energy carried by the laser device emitting the laser or by each pulse within the laser beam.

[0050] F th Ablation threshold flux (unit: J / cm) 2 This is the minimum energy density required to ablate a material. Below this value, the material will only be heated or modified, but will not be effectively removed. This is a key property of the material itself.

[0051] F0 is the laser flux (or energy density), measured in J / cm². 2 This is the actual energy density acting on the material surface, usually expressed as F0 = E. p / A is calculated, where A is the area of ​​the laser spot at the laser focal point.

[0052] S204: Microfluidic channels are constructed on the surface of a metal thin film, and the microfluidic channels are connected to the region where the laser-induced periodic surface structure is located.

[0053] Optionally, the microfluidic channel includes a main channel and multiple branch channels. One end of the main channel is connected to an external fluid input device. Each branch channel communicates with the main channel, and each branch channel has at least one serpentine mixing zone.

[0054] The main channel serves as the flow trunk for the etchant, receiving input from external etchant input devices. Multiple branch channels connect to the main channel, guiding the etchant to different areas of the LIPSS or distributing it. Each branch channel has at least one serpentine mixing zone, typically constructed with U-shaped or S-shaped bends. This zone extends the flow path, promoting rapid and uniform mixing of sequentially injected reagents (such as the etchant and pH adjusting solution), ensuring a uniform liquid concentration reaching the reaction zone (i.e., the LIPSS area).

[0055] In this embodiment, the inlet section of the main channel is a Y-shaped channel. In other words, the main channel has two inlet ends and one outlet end, one inlet end for introducing a pH adjusting solution to adjust the pH value within the microfluidic channel, and the other inlet end for introducing a corrosive agent from the corrosive solution.

[0056] For example, the width of the main channel (that is, the shortest distance between the main channel and the two side walls) is W = 50-200 μm, and the depth-to-width ratio of the main channel is 1:1 to 1:5; the width of the branch channel is w = W / 5-W / 2; and the length of the serpentine mixing zone along the length direction of the main channel is L > 10W.

[0057] This configuration ensures the main channel is wide enough, allowing fluid to flow smoothly from its inlet to each branch channel, reducing the risk of blockage and preventing significant pressure drops. The branch channels, through their width design, can better distribute flow and increase velocity. The serpentine mixing zone, utilizing its length, efficiently mixes the distributed fluid, resulting in a uniform concentration of the corrosive solution.

[0058] Optionally, S204 includes: bonding a microfluidic chip with microfluidic channels to a metal thin film with an IPSS structure, such that the microfluidic channels cover the area where the LIPSS structure is located.

[0059] Optionally, the microfluidic channel chip is a structural component based on polydimethylsiloxane (PDMS). The surface molecules of the inner wall of the microfluidic channel are modified with hydrophilic functional groups.

[0060] Among the above implementation methods, PDMS is often used to prepare micro- and nano-scale microchannels, i.e., to form microfluidic channels, because its performance is controllable, its preparation is convenient, and its cost is low.

[0061] Because PDMS is highly hydrophobic, the microfluidic channels within it are difficult to wet with aqueous solutions, requiring high external pressure to pump the etchant into the channels. Therefore, designing hydrophilic groups on the inner wall surface of the microfluidic channels allows for good wetting of the channels with aqueous solutions, enabling the etchant to spontaneously and rapidly fill the entire channel via capillary forces, thus improving its fluidity. In other words, modifying the surface molecules of the microfluidic channel inner wall with hydrophilic functional groups effectively solves the channel blockage problem caused by non-specific adsorption of polydimethylsiloxane on the inner wall of the microfluidic channel during etchant delivery. This ensures the accuracy and consistency of etchant delivery, laying the foundation for precise dynamic control of the corrosion process.

[0062] Optionally, hydrophilic functional groups are modified on the inner wall of the microfluidic channel by surface grafting, and the hydrophilic functional groups are any one of carboxyl, hydroxyl, sulfonic acid and amino groups.

[0063] Grafting means permanently connecting new molecular chains to the surface of a material through a chemical reaction. After grafting hydrophilic functional groups, the inner wall of the microfluidic channel changes from hydrophobic to hydrophilic.

[0064] In this embodiment of the disclosure, the step of "bonding a microfluidic chip with a microfluidic channel to a metal thin film with an IPSS structure" can be performed according to the following steps:

[0065] (1) Align the microfluidic channel with the region where the laser-induced periodic surface structure is located, so that the region where the laser-induced periodic surface structure is located is within the microfluidic channel.

[0066] In this embodiment, before alignment, the surfaces of the microfluidic chip (such as a PDMS chip) with microfluidic channels and the substrate material with LIPSS are cleaned (e.g., ultrasonically cleaned sequentially with acetone, ethanol, and deionized water), and then dried with nitrogen. The surfaces of the PDMS chip and the substrate material are then treated with oxygen plasma to thoroughly clean the surfaces, remove organic contaminants, and simultaneously activate the surfaces, generating a large number of silanol groups (-Si-OH) on the surfaces of the PDMS and the substrate material, creating conditions for subsequent irreversible bonding.

[0067] With the aid of a microscope or visual alignment system, the inlet, outlet, and channel orientation of the microfluidic channel are precisely aligned with the LIPSS processing area on the substrate to ensure that the area of ​​LIPSS to be etched is completely under the microfluidic channel and maintains fluid communication with the inlet and outlet.

[0068] (2) Pressing the metal film and the substrate material on which the metal film is located together to achieve initial bonding between the microfluidic chip and the metal film.

[0069] The aligned PDMS chip is gently brought into contact with the substrate material, and the two initially adhere together due to intermolecular forces (or hydrogen bonds formed between silanol groups after plasma treatment).

[0070] (3) Heat the microfluidic chip and the metal film that are initially bonded to make the microfluidic chip and the substrate material firmly bonded.

[0071] The initially bonded PDMS chip and substrate material are placed on a heating stage (e.g., 60-80℃) and heated and kept at that temperature (e.g., 10-30 minutes) to promote further condensation reaction between the silanol groups, forming strong Si-O-Si covalent bonds, thus achieving irreversible permanent bonding between the PDMS chip and the substrate material.

[0072] The strength and sealing of the bond between the PDMS chip and the substrate material directly determine the success of microfluidic etching. If the bond is weak, the etching solution will leak, completely destroying the sample and the experiment. Therefore, reliable bonding is a prerequisite and guarantee for subsequent methods, and it is itself an important step in the method provided in this disclosure.

[0073] S205: Delivers the etchant to the area where the LIPSS is located via a microfluidic channel.

[0074] Optionally, the etching solution includes nanocapsules containing an etchant, a transport fluid for delivering the nanocapsules, and a pH-adjusting fluid. The nanocapsules are pH-responsive nanocapsules.

[0075] pH-responsive nanocapsules contain a core encapsulated with a high concentration of corrosive agent. The transport fluid is a neutral pH, water-based buffer solution used to suspend and transport the nanocapsules. The pH-adjusting fluid, an acidic or alkaline solution, is used to change the pH value inside the microfluidic channel as needed to trigger the responsive release mechanism of the nanocapsules.

[0076] pH-responsive nanocapsules refer to nanocapsules containing corrosives that can be released in response to external pH signals, thereby achieving precise control.

[0077] The pH adjustment solution is 0.1 mol / L H3PO4, and the pH response value of the nanocapsules is 3.0 ± 0.1.

[0078] In this embodiment, the pH adjustment solution can be dynamically injected into the microfluidic channel through a precision injection pump based on the calculation results of the Density Functional Theory (DFT) interface reaction model, and mixed with the transport liquid containing nanocapsules, thereby achieving precise control of the corrosion process.

[0079] When delivering the etchant to the LIPSS region through the microfluidic channel, the flow rate of the etchant is 0.1-1 ml / min, and the temperature of the etchant is 25.0±0.1℃.

[0080] The DFT interfacial reaction model refers to using density functional theory to simulate the interaction between etchant molecules and atoms on the surface of metal / semiconductor materials, thereby predicting the ease (activation energy) and selectivity of the corrosion reaction from the most fundamental quantum mechanical principles. This makes it possible to rationally design etchant formulations and precisely control the corrosion process.

[0081] In other words, during the actual corrosion process, the amount of pH-adjusting fluid (such as acid or alkali) injected into the microfluidic channel is controlled according to the instructions of the DFT interface reaction model. Changes in pH trigger the rupture of the shells of pH-responsive nanocapsules, releasing the fixed-concentration corrosive agent encapsulated within. By controlling the injection amount of pH-adjusting fluid, the release rate of the nanocapsules is indirectly controlled, thereby controlling the concentration of the actual corrosive agent acting on the material surface.

[0082] In this embodiment, the concentration of the pH adjustment solution in the microfluidic channel is dynamically adjusted so that the corrosion rate ratio between the metal film and the substrate material on which the metal film is located is between 1:0.2 and 1:5.

[0083] By controlling the amount of pH-adjusting solution, the pH value of the environment in which the nanocapsules are located can be naturally adjusted, thereby controlling the rate at which the nanocapsules release corrosive agents, and ultimately controlling the corrosion rate ratio of metal films and other materials.

[0084] Optionally, the etchant is designed according to the different metal thin films and the substrate material on which the metal thin films are deposited. For example, when the metal thin film is a gold film deposited on a SiO2 dielectric layer, the etchant includes 0.1 mol / L KI, 0.01 M / L I2, and 0.5 wt% benzotriazole.

[0085] For example, when the metal thin film is a composite metal layer deposited on a SiO2 dielectric layer, and the composite metal layer includes a cadmium film and a gold film deposited on the cadmium film, the etchant includes a first etchant for etching the gold film and a second etchant for etching the cadmium film. The first etchant includes 0.1 M / L KCN and 10 mMOL / L K3[Fe(CN)6], with a selectivity >200:1. The second etchant includes 0.3% HF and 50 mMOL / L H2O2, with an etching rate of 18 nm / min. In this case, etching is performed by delivering the etchant to the LIPSS region through a microfluidic channel, including:

[0086] The first etchant is delivered to the LIPSS region via a microfluidic channel at a flow rate of 0.50 ± 0.02 ml / min and a temperature of 25.0 ± 0.1 °C. The first etchant comprises nanocapsules containing a first etchant and a transport fluid for delivering these nanocapsules.

[0087] After the gold film is removed by the first etching solution, a second etching solution is delivered to the LIPSS region through a microfluidic channel at a flow rate of 0.50 ± 0.02 ml / min and a temperature of 25.0 ± 0.1 °C. The second etching solution comprises nanocapsules containing a second etchant and a transport fluid for delivering these nanocapsules.

[0088] For example, when the metal thin film is the Au gate in a GaN HEMT device, the etchant includes 0.05 mol / L disodium ethylenediaminetetraacetic acid (EDTA-2Na), used to complex Ga. 3 + ), 0.1 mol / L (NH4)2S2O8 (used as an oxidant), and 5 parts per million (ppm) of ruthenium ions (RuO42-, used to catalyze the dissolution of Au). 5 ppm means that there are 5 milligrams of RuO42- per liter of solution.

[0089] On the other hand, embodiments of this disclosure also provide a metal corrosion system applicable to the aforementioned metal corrosion methods.

[0090] like Figure 3 As shown, the metal corrosion system includes a laser processing module 301, a microfluidic channel module 302, and a corrosion control module 303. The laser processing module is used to form LIPSS on the surface of a metal thin film.

[0091] The microfluidic channel module 302 is used to construct microfluidic channels on the surface of a metal thin film, and the microfluidic channels are connected to the region where the laser-induced periodic surface structure is located.

[0092] The corrosion control module 303 is used to deliver a corrosion liquid to the area where the laser-induced periodic surface structure is located through a microfluidic channel to form a nanostructure on the surface of the metal film.

[0093] The above corrosion systems have the same beneficial effects as the aforementioned corrosion methods, and will not be described in detail here.

[0094] In this embodiment, the laser processing module 301 includes a femtosecond laser source, a spatial light modulator, and a five-axis motion platform. The wavelength of the femtosecond laser source can be 1030±5nm, and the pulse width is <500fs. The spatial light modulator is used to form a LIPSS structure with a spatial period of 50-200nm. The five-axis motion platform is used to ensure the positioning accuracy of the formed LIPSS.

[0095] The microfluidic channel module 302 is a PDMS chip comprising multiple layers of microfluidic channels. The main channel width of the microfluidic channels is 50-200 μm, with an aspect ratio of 1:1 to 1:5. The PDMS chip also integrates an electrochemical sensor array, such as sensors for monitoring pH (accuracy ±0.01) and redox potential (±5 mV).

[0096] The corrosion control module 303 has a pre-stored database of the DFT interface reaction model so that the composition of the corrosion solution can be adjusted in real time according to the calculation results.

[0097] Furthermore, the corrosion control module 303 also features a real-time feedback unit, which can be a scanning electron microscope (SEM). The SEM can detect the surface of the metal thin film in real time. The corrosion control module 303 can adjust the laser power online based on the image detected by the SEM.

[0098] The above methods are illustrated with specific examples below:

[0099] 1. Fabrication of gold electrodes for photonic integrated circuits:

[0100] 1.1 Substrate material preparation

[0101] The substrate material used is a 4-inch p-type Si(100) wafer (thickness 525±25μm).

[0102] Cleaning process: Cleaning is performed according to RCA standards. The first step involves cleaning with a cleaning agent (NH4OH:H2O2:H2O = 1:1:5, 75℃) for 10-15 minutes to remove organic matter from the surface of the substrate material. The second step involves cleaning with a hydrofluoric acid buffered oxide etchant (BOE 7:1, which is NH4F:HF = 7:1) for 30 seconds.

[0103] 1.2 Dielectric layer deposition (i.e., the surface oxidation treatment mentioned above):

[0104] The dielectric layer was deposited using PECVD. The process parameters were: SiH4 / N2O gas flow rate of 30 / 90 sccm, RF power of 50 W, and pressure of 200 mTorr. The resulting SiO2 dielectric layer thickness was 500 ± 5 nm (measured with an ellipsometry), and the refractive index measured at a wavelength of 633 nm (typically the wavelength of a helium-neon laser) was 1.46 ± 0.01.

[0105] 1.3 Metal Thin Film Deposition

[0106] Metal thin film deposition is performed using an electron beam evaporation system.

[0107] Process parameters: Base vacuum: <5×10 -6 Torr; Deposition rate: 0.3 nm / s (quartz crystal monitoring); Film structure includes a 5 nm Cr (99.95% purity) adhesion layer and a 200 nm Au (99.999% purity) conductive layer.

[0108] Performance specifications: Sheet resistance: 0.25±0.02Ω / □ (four-probe method); Roughness: Ra=0.8nm (AFM 5μm×5μm scan).

[0109] 1.4 Laser processing

[0110] Laser wavelength: 515±2nm (green light band); pulse width: 450±20fs; repetition frequency: 5kHz (adjustable).

[0111] Optical path: beam expander (5× beam expander); galvanometer scanning system (Scanlab intelli SCAN III).

[0112] Processing parameters: Energy density F calculation:

[0113]

[0114] Where Ep is the laser pulse energy (Ep = 3 mJ); d is the laser beam diameter (d = 18 μm). That is, using a laser pulse with an energy of 3 microjoules, focused onto an 18-micrometer spot, a beam of 1.2 J / cm² is generated. 2 Energy density.

[0115] Scanning strategy: Line spacing: 50nm (70nm periodic stripes); Scanning speed: 250mm / s (pulse overlap rate 60%); Environmental control: Argon glove box (O2<5ppm, H2O<1ppm).

[0116] Quality verification:

[0117] LIPSS characterization: Period: 70±3nm (SEM measurement, accelerating voltage 5kV); Depth: 25±2nm (white light interferometer).

[0118] 1.5 Corrosion of Microfluidic Channels

[0119] Microfluidic channel design: PDMS chip: (PDMS prepolymer and curing agent mixed in a 10:1 mass ratio);

[0120] Microfluidic channel structure: Y-shaped structure (main channel 100μm×50μm); Surface treatment: oxygen plasma activation (50W, 30s).

[0121] Corrosion agent formulation: 0.1M KI (≥99.5%); 0.01M I2 (ACS grade, purified by recrystallization); 0.5wt% benzotriazole (BTA, inhibitor purity 99.9%).

[0122] pH adjustment solution: 0.1M H3PO4, pH = 3.0 ± 0.1. Transport solution: deionized water.

[0123] Process control: Etching solution flow rate: 0.50±0.02ml / min (driven by peristaltic pump); Etching solution temperature: 25.0±0.1℃ (controlled by PID heating plate);

[0124] Endpoint detection:

[0125] The corrosion process was monitored in real time using an online optical monitoring device (Ocean Optics HR4000 spectrometer). The corrosion process was terminated when the intensity of the characteristic peak at 620 nm in the Au film decreased to 10% of the initial value corresponding to the start of corrosion. In this way, closed-loop control of the morphological transformation of gold nanostructures can be achieved by real-time monitoring of the 620 nm characteristic peak of Au.

[0126] 1.5. Performance Characterization

[0127] Morphological analysis:

[0128] Test Project Measurement results Test equipment Line width uniformity 00±1.2nm (n=50,3σ) SEM Sidewall angle 89.2±0.5° FEI Helios G4 UX Surface roughness Ra = 1.8nm AFM

[0129] Electrical properties:

[0130] Resistance calculations further confirmed that the prepared gold thin film (200 nm Au) has excellent conductivity: its resistivity (ρ = 2.44 μΩ·cm) is close to the theoretical value of pure gold, and the resistance value is precisely controlled (12.5 ± 0.3 Ω), with good repeatability, which fully meets the requirements for electrode preparation of high-quality micro and nano devices.

[0131] Reliability data:

[0132] Process capability index: CPK = 1.72 (USL / LSL = ±3nm); Self-healing response time: 80±15ms (observed by high-speed camera)

[0133] 1.6 Comparative Experiment

[0134] Comparison items This disclosure Traditional wet corrosion Plasma etching Line width error (3σ) ±1.2nm ±6.5nm ±3.8nm Damage layer thickness <2nm 5-10nm 15-20nm Energy consumption 0.8kWh / piece 0.5kWh / piece 8.2kWh / piece

[0135] The above comparison demonstrates that the method disclosed herein can control the error to the atomic scale (±1.2 nm, approximately a few atoms wide) when etching Au films, far superior to traditional wet etching (±6.5 nm) and plasma etching (±3.8 nm). Furthermore, the method disclosed herein causes less damage to the material, implying better electrical properties and reliability of the processed material. Moreover, in terms of energy consumption, the etching process of this disclosure is only one-tenth that of plasma etching.

[0136] 2. Fabrication of Ti / Au composite electrodes for silicon-based optical modulators:

[0137] The operating procedure is the same as above, except that the corrosive solution used and the monitoring conditions are different.

[0138] 1. Selective corrosive agents:

[0139] Au corrosion: The etchant is 0.1M KCN ​​+ 10mM K3[Fe(CN)6] (selectivity >200:1)

[0140] Ti etching: Etcher is 0.3% HF + 50mM H2O2 (etching rate 18nm / min)

[0141] Interface control: X-ray photoelectron spectroscopy (XPS) monitoring showed that the Ti2p peak (binding energy 454.2 eV) intensity decreased to 5% before termination. Post-treatment with NH4OH (25 wt%, 30 s) reduced the Si surface state density to <1 × 10⁻⁶. 10 cm -2 ·eV -1 .

[0142] 2. Photoelectric properties

[0143] wavelength Insertion loss (dB / cm) Traditional craftsmanship (dB / cm) 1310nm 0.28±0.03 0.52±0.08 1550nm 0.25±0.02 0.48±0.06

[0144] The above comparison shows that when the method of this disclosure is used in the fabrication of Ti / Au composite electrodes for silicon-based optical modulators, the optical performance of the resulting device is superior to that of traditional processes.

[0145] As can be seen from the table above, the insertion loss of the device obtained by the method disclosed herein (insertion loss is a measure of the power attenuation of an optical signal after passing through an optical waveguide, measured in decibels per centimeter; the lower the value, the better) is much lower than that of the traditional process. Lower insertion loss means that light can travel a longer distance in the waveguide while maintaining sufficient intensity, which further demonstrates that the optical performance of the device fabricated by the method is superior to that of the traditional process.

[0146] 3: Au gate fabrication in GaN HEMT devices:

[0147] The operating procedure is the same as above, except that the corrosive solution used is different.

[0148] 3.1. Corrosion Agent Design

[0149] Quantum chemical calculations guided the formulation to 0.05M EDTA-2Na (complexed Ga). 3+ ); 0.1M (NH4)2S2O8 (oxidant); 5ppm RuO4 2- (Catalyzed Au dissolution)

[0150] DFT simulation results:

[0151] Au(111) activation energy: 0.72 eV; GaN(0001) activation energy: 1.35 eV.

[0152] In other words, when designing etchants, DFT calculations can be used to simulate and predict which chemical formulation is most effective at the atomic level. First, the etchant is determined, and then verified through DFT calculations.

[0153] For example, calculations show that the activation energy of the etchant Au(111) is 0.72 eV, while that of GaN(0001) is 1.35 eV. This indicates that with the same etchant, the etching reaction of gallium nitride is extremely difficult to occur, and the rate is extremely slow. The etching rate of this etchant on gold is much faster than that on gallium nitride. Its selectivity (Au etching rate / GaN etching rate) can reach a very high value. This allows for efficient and rapid etching of the gold gate while leaving the underlying gallium nitride channel layer almost intact, further verifying the effectiveness of this etchant. Conversely, DFT calculations can predict the optimal etchant formulation in advance based on the underlying principles of quantum mechanics. This is not only efficient and cost-effective, but more importantly, it makes the process controllable, predictable, and optimizable.

[0154] 3.2. Device Performance

[0155] parameter This disclosure Traditional crafts Gate leakage current 0.8 nA / mm 15nA / mm <![CDATA[Cutoff frequency (f t )]]> 42GHz 28GHz

[0156] The above comparison shows that when the method of this disclosure is used in the Au gate processing of GaN HEMT devices, the optical performance of the resulting devices is superior to that of traditional processes.

[0157] Based on the table above, the gate leakage current of the device fabricated by the method of this disclosure is lower than that of conventional processes, indicating that the gate oxide layer prepared by the method of this disclosure has an extremely low defect density. Furthermore, the cutoff frequency of the device fabricated by this disclosure is increased from 28 GHz in conventional processes to 42 GHz, representing a performance improvement of nearly 50%.

[0158] The above are merely optional embodiments of this disclosure and are not intended to limit this disclosure. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this disclosure should be included within the protection scope of this disclosure.

Claims

1. A method for metal corrosion, characterized in that, The metal corrosion method includes: Laser-induced periodic surface structures are formed on the surface of a metal thin film; Microfluidic channels are constructed on the surface of the metal thin film, and the microfluidic channels are connected to the region where the laser-induced periodic surface structure is located; The microfluidic channel delivers an etchant to the region containing the laser-induced periodic surface structure to form a nanostructure on the surface of the metal film.

2. The metal corrosion method according to claim 1, characterized in that, The process of forming a laser-induced periodic surface structure on the surface of a metal thin film includes: The surface of the metal thin film is scanned using a femtosecond laser, and the spatial period of the laser-induced periodic surface structure is 0.8-1.2 times the wavelength of the femtosecond laser.

3. The metal corrosion method according to claim 1, characterized in that, The depth of the laser-induced periodic surface structure satisfies the following formula: d=k(E p / F th )ln(F0 / F th ); Where d is the depth of the laser-induced periodic surface structure; k is a material constant; E p The energy carried by each laser pulse; F0 is the laser flux; F th This represents the threshold flux.

4. The metal corrosion method according to any one of claims 1-3, characterized in that, The microfluidic channel includes a main channel and multiple branch channels; One end of the main channel is connected to an external fluid input device; Each of the branch channels is connected to the main channel, and each of the branch channels has at least one serpentine mixing zone.

5. The metal corrosion method according to any one of claims 1-3, characterized in that, The process of constructing microfluidic channels on the surface of the metal thin film includes: A microfluidic chip having the microfluidic channel is bonded to the metal thin film having the laser-induced periodic surface structure, such that the microfluidic channel covers the area where the laser-induced periodic surface structure is located.

6. The metal corrosion method according to claim 5, characterized in that, The microfluidic chip is a structural component with polydimethylsiloxane as the substrate material; The surface molecules of the inner wall of the microfluidic channel are modified with hydrophilic functional groups.

7. The metal corrosion method according to claim 6, characterized in that, The hydrophilic functional group is modified on the inner wall of the microfluidic channel by surface grafting, and the hydrophilic functional group is any one of carboxyl, hydroxyl, sulfonic acid and amino groups.

8. The metal corrosion method according to any one of claims 1-3, characterized in that, The corrosive liquid includes nanocapsules containing corrosive agents, a transport liquid for delivering the nanocapsules, and a pH adjusting liquid. The nanocapsules are pH-responsive nanocapsules.

9. The metal corrosion method according to any one of claims 1-3, characterized in that, The process of delivering etchant to the region containing the laser-induced periodic surface structure via the microfluidic channel for etching includes: The concentration of the pH-adjusting solution in the microfluidic channel is dynamically adjusted so that the corrosion rate ratio of the metal film to the substrate material on which the metal film is located is between 1:0.2 and 1:

5.

10. A metal corrosion system, characterized in that, The metal corrosion system includes a laser processing module, a microfluidic channel module, and a corrosion control module; The laser processing module is used to form laser-induced periodic surface structures on the surface of a metal thin film; The microfluidic channel module is used to construct microfluidic channels on the surface of the metal thin film, and the microfluidic channels are connected to the region where the laser-induced periodic surface structure is located; The corrosion control module is used to deliver an etchant to the region where the laser-induced periodic surface structure is located through the microfluidic channel to form a nanostructure on the surface of the metal film.

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