Easily peelable metal stacked film structure, fabrication method and semiconductor device

Abstract

This invention relates to the field of semiconductor technology, specifically to an easily peelable metal stacked film structure, its fabrication method, and a semiconductor device. The easily peelable metal stacked film structure includes a metal layer, an intermediate layer, and a mask layer sequentially stacked along a predetermined direction; the intermediate layer is made of poly(3,4-ethylenedioxythiophene)-polystyrene sulfonic acid; when peeling the mask layer from the metal layer, the intermediate layer is dissolved and removed using a cleaning solution, allowing the mask layer to detach from the metal layer. This achieves the effect of removing the mask layer without damage.

Description

Technical Field

[0001] This invention relates to the field of semiconductor technology, and specifically to an easily peelable metal stacked film structure, its preparation method, and a semiconductor device. Background Technology

[0002] In the mid-stage processes of integrated circuit chip manufacturing, when precise characterization of the electrical properties of metal layers is required, the mask layer covering their surface must first be removed. Currently, the industry's traditional mask layer removal process mainly relies on plasma dry etching technology: this involves introducing etching gas to generate plasma under the influence of a radio frequency electric field, utilizing the chemical reaction and physical bombardment effect between active particles and the mask layer to achieve selective removal. However, this traditional process has several technical limitations, specifically...

[0003] 1) Incomplete mask layer removal, resulting in residue: Due to the difficulty in precisely controlling the etching selectivity of the mask layer and metal layer, and the significant impact of fluctuations in parameters such as cavity pressure and gas flow rate on the wafer surface, it is highly likely that the mask layer will not be completely etched in certain areas. Residual mask layers will directly cover the metal layer surface, preventing subsequent electrical probes from forming effective contact with the metal layer. This interferes with the detection of leakage current and the accuracy of the equivalent oxide layer thickness measurement, potentially leading to misjudgments of leakage location or leakage current magnitude.

[0004] 2) The metal layer is susceptible to damage, affecting process stability: During the etching process, if the physical bombardment energy of the plasma is not properly controlled, it can directly cause pits, roughening, or uneven thickness on the surface of the metal layer. As the core conductive layer of the chip, the uniformity of the metal layer's thickness directly determines the consistency of the electron transport path. Excessive thickness differences can lead to fluctuations in electron mobility and deviations in resistance values, ultimately resulting in a significant increase in the dispersion of electrical performance test results for batches of chips, severely affecting process robustness.

[0005] 3) Poor reliability of electrical testing and significant interference from contact resistance: Even if the mask layer is completely removed, the surface of the etched metal layer is prone to oxide layer formation and increased roughness. Furthermore, traditional manual probe-based electrical tests suffer from unstable physical contact between the probe and the metal layer surface, such as uneven contact pressure and surface oxide layer obstruction, resulting in significant contact resistance. This contact resistance is superimposed on the test circuit, leading to decreased sensitivity in leakage current detection and systematic deviations in the calculation of the equivalent oxide layer thickness, failing to accurately reflect the actual performance of the device. Summary of the Invention

[0006] The purpose of this invention is to provide an easily peelable metal stacked film structure, preparation method and semiconductor device, which can achieve the effect of removing the mask layer without damage.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0008] In a first aspect, the present invention provides an easily peelable metal stacked film structure, comprising a metal layer, an intermediate layer and a mask layer stacked sequentially along a predetermined direction;

[0009] The intermediate layer is made of poly(3,4-ethylenedioxythiophene)-polystyrene sulfonic acid;

[0010] When peeling off the mask layer on the metal layer, the intermediate layer is dissolved and removed by a cleaning solution, so that the mask layer is detached from the metal layer.

[0011] Furthermore, it also includes an isolation layer formed in the intermediate layer, the isolation layer separating the intermediate layer into a first layer and a second layer along a predetermined direction, the first layer being connected to the metal layer and the second layer being connected to the mask layer; the dissolution rate of the isolation layer in the cleaning solution is higher than the dissolution rate of the intermediate layer in the cleaning solution.

[0012] Furthermore, the material of the isolation layer is at least one of polyvinylpyrrolidone, polyvinyl alcohol, and hydroxypropyl methylcellulose.

[0013] Furthermore, the cleaning solution includes water, ethanol, acetone, ethylene glycol, weak acid, weak base, oxidizing agent, reducing agent, and organic solvent.

[0014] Furthermore, the material of the metal layer includes at least one of aluminum, copper, silver, gold, aluminum-copper alloy, and titanium-tungsten alloy.

[0015] Furthermore, the material of the mask layer includes at least one of titanium nitride, tantalum nitride, silicon nitride, and silicon dioxide.

[0016] Furthermore, the thickness of the intermediate layer is 80nm~2000nm.

[0017] Secondly, the present invention provides a method for preparing an easily peelable metal stacked film structure, comprising:

[0018] An intermediate layer is deposited on one side surface of the metal layer and then cured by heating after deposition. The intermediate layer is made of poly(3,4-ethylenedioxythiophene)-polystyrene sulfonic acid.

[0019] A mask layer is deposited on the intermediate layer to obtain the aforementioned easily peelable metal stacked film structure.

[0020] Furthermore, the temperature for heat curing is set to 45℃~55℃, and the time is set to 90s~150s.

[0021] Thirdly, the present invention provides a semiconductor device comprising the aforementioned easily peelable metal stacked film structure.

[0022] The present invention has the following unexpected beneficial effects:

[0023] The easily peelable metal stacked film structure of this invention includes a metal layer, an intermediate layer, and a mask layer stacked sequentially along a predetermined direction. The intermediate layer is made of poly(3,4-ethylenedioxythiophene)-polystyrene sulfonic acid. On the one hand, the intermediate layer ensures good adhesion to both the metal layer and the mask layer, while also being dissolved and removed under the action of a cleaning solution. This allows the mask layer to detach smoothly from the metal layer, avoiding damage to the metal layer and achieving the effect of removing the mask layer without damage. On the other hand, the poly(3,4-ethylenedioxythiophene)-polystyrene sulfonic acid meets the requirements of dry etching. During etching, after the molecular chains of the intermediate layer break or recombine, a protective polymer film forms on the sidewalls, effectively inhibiting lateral etching and ensuring that the intermediate layer forms a vertical cross-sectional profile, thus guaranteeing the structural accuracy and performance stability of the semiconductor device pattern transfer. Attached Figure Description

[0024] Figure 1 A schematic diagram of one embodiment of the easily peelable metal stacked film structure described in this invention is shown.

[0025] Figure 2 A schematic diagram of another embodiment of the easily peelable metal stacked film structure described in this invention is shown.

[0026] Figure 3 A cross-sectional schematic diagram of the dissolution process of the intermediate layer described in this invention is shown.

[0027] Figure 4 A schematic diagram illustrating the principle of the dissolution process of the intermediate layer described in this invention is shown.

[0028] Figure 5 A macroscopic schematic diagram of the dissolution process of the intermediate layer described in this invention is shown.

[0029] Figure 6 A schematic diagram of the detection of the metal layer described in this invention is shown.

[0030] Figure 7 A schematic diagram of the easily peelable metal stacked film structure before dry etching is shown.

[0031] Figure 8 A schematic diagram of the easily peelable metal stack film structure after dry etching is shown.

[0032] In the figure, 1—metal layer, 2—intermediate layer, 21—first layer, 22—second layer, 3—mask layer, 4—isolation layer, 5—probe, 6—photoresist, 7—substrate. Detailed Implementation

[0033] The embodiments of the present invention will be described below with reference to the accompanying drawings and preferred embodiments. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be understood that the preferred embodiments are only for illustrating the present invention and not for limiting the scope of protection of the present invention.

[0034] It should be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of the present invention. Therefore, the drawings only show the components related to the present invention and are not drawn according to the actual number, shape and size of the components in the actual implementation. In the actual implementation, the form, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.

[0035] In one embodiment, the present invention provides an easily peelable metal stacked film structure, see [link to previous embodiment]. Figure 1 As shown, the metal stacked film structure includes a metal layer 1, an intermediate layer 2, and a mask layer 3 stacked sequentially along a predetermined direction. The intermediate layer 2 is made of poly(3,4-ethylenedioxythiophene)-polystyrene sulfonic acid. When peeling off the mask layer 3 on the metal layer 1, the intermediate layer 2 is dissolved and removed by a cleaning solution, so that the mask layer 3 is detached from the metal layer 1.

[0036] Because the intermediate layer 2 is made of poly(3,4-ethylenedioxythiophene)-polystyrene sulfonic acid, it can ensure good bonding with both the metal layer 1 and the mask layer 3, while also being dissolved and removed by the cleaning solution. This allows the mask layer 3 to detach smoothly from the metal layer 1, avoiding damage to the metal layer 1 and achieving the effect of removing the mask layer without damage. Furthermore, the poly(3,4-ethylenedioxythiophene)-polystyrene sulfonic acid meets the requirements of dry etching. During etching, after the molecular chains of the intermediate layer 2 break or recombine, a protective polymer film forms on the sidewalls, effectively suppressing lateral etching and ensuring that the intermediate layer 2 forms a vertical cross-sectional profile. This guarantees the structural accuracy and performance stability of the semiconductor device pattern transfer.

[0037] Furthermore, this embodiment only requires dissolving and removing the intermediate layer 2 with a cleaning solution to complete the peeling of the mask layer 3, eliminating the need for complex processes and special equipment. This reduces operational difficulty and production costs, improves production efficiency, and facilitates large-scale production applications. In practical applications, the cleaning solution can be recycled after simple impurity removal treatment, further reducing production costs, improving resource utilization, and aligning with the principles of environmental protection and sustainable development.

[0038] It should be noted that during the deposition process, metal layer 1 is prone to defects such as surface protrusions, depressions, pinholes, or particles due to factors such as substrate roughness and uneven deposition rate. PEDOT, or poly(3,4-ethylenedioxythiophene), is a conductive polymer with planarization capabilities, and its solution exhibits excellent flowability and spreadability during spin coating. For tiny protrusions on the surface of metal layer 1, such as nanoscale grain clusters, the PEDOT solution can fill the gaps around them through gravity and surface tension, forming a smooth transition capping layer. For depressions or pinholes, the PEDOT solution can fully wet and fill them, reducing the risk of discontinuity in subsequent film layers (such as isolation layers and mask layers) caused by voids. This planarization effect provides a uniform deposition substrate for the upper film layers, avoiding film thickness deviations or localized stress concentrations caused by surface undulations.

[0039] Furthermore, PEDOT's low impedance and high stability characteristics mean that even if some residue remains after dissolution, it will not affect subsequent electrical performance testing of the metal layer. This ensures the robustness of key test results such as cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and constant current charge-discharge (CP), thereby improving production efficiency.

[0040] For example, semiconductor device pattern transfer specifically includes:

[0041] 1) Pretreatment and photoresist coating: First, the upper surface of the mask layer 3 is cleaned to remove impurities and the natural oxide layer. Then, photoresist 6 is uniformly coated by spin coating to form a photosensitive film of uniform thickness. After coating, a soft baking process is performed to remove the solvent in the photoresist 6, thereby enhancing the adhesion between the photoresist 6 and the mask layer 3.

[0042] 2) Exposure and Development: A photolithography machine is used to selectively expose the photoresist 6. Depending on the pattern requirements, ultraviolet or extreme ultraviolet light is projected through a mask to alter the chemical properties of the photoresist in the exposed areas. After exposure, development removes the photoresist in specific areas, forming a patterned window on the photoresist layer that matches the target pattern. The window area exposes the underlying mask layer 3. (See [link to documentation]). Figure 7 As shown, the pattern definition of the photoresist is completed.

[0043] 3) Step-by-step dry etching and pattern transfer: Using patterned photoresist 6 as a mask, the pattern is sequentially transferred to mask layer 3, intermediate layer 2, and metal layer 1 through a multi-step dry etching process. The specific process is as follows:

[0044] The first step is mask layer etching: an etching gas with high selectivity for mask layer 3 is selected, such as a mixture of CF4 and O2 used for etching silicon nitride. Plasma is generated in a vacuum reaction chamber by excitation with an RF power supply. Active ions in the plasma are accelerated by an electric field and vertically bombard the surface of mask layer 3, simultaneously reacting chemically with the mask material to generate volatile products, which are then removed by a vacuum pump. This process removes only the mask layer 3 in the windowed areas, retaining the mask layer 3 and photoresist 6 in the non-windowed areas, thus transferring the pattern to mask layer 3.

[0045] The second step is photoresist removal: After the mask layer 3 is patterned, the remaining photoresist 6 is removed using an oxygen plasma ashing process, so that the patterned mask layer 3 is fully exposed and used as a hard mask for subsequent etching.

[0046] The third step is the etching of intermediate layer 2 and metal layer 1: using patterned mask layer 3 as a mask, appropriate etching gases and process parameters are selected according to the material properties of intermediate layer 2 and metal layer 1 (e.g., a mixture of Cl2 and Ar is used when etching copper). Through the synergistic effect of physical bombardment (ion sputtering) and chemical action (active free radical reaction) of plasma, see [link to documentation]. Figure 8 As shown, the intermediate layer 2 and the metal layer 1 in the window area are etched sequentially, ensuring no significant damage to the underlying substrate 7. During the etching process, after the molecular chains of the intermediate layer 2 break or recombine, a protective polymer film is formed on the sidewalls, which effectively suppresses lateral etching, ensuring that the intermediate layer 2 forms a vertical cross-sectional profile, thus guaranteeing the structural accuracy and performance stability of the semiconductor device pattern transfer.

[0047] 4) Post-etching treatment: After etching is completed, residual etching byproducts, intermediate layer 2 and mask layer 3 are removed by cleaning solution, and finally a functional pattern that is completely consistent with the initial design is formed on the surface of metal layer 1, completing the entire pattern transfer process.

[0048] As a preferred embodiment of the present invention, see Figure 2 As shown, the easily peelable metal stacked film structure also includes an isolation layer 4 formed in the intermediate layer 2. The isolation layer 4 isolates the intermediate layer 2 into a first layer 21 and a second layer 22 along a predetermined direction. The first layer 21 is connected to the metal layer 1, and the second layer 22 is connected to the mask layer 3. The dissolution rate of the isolation layer 4 in the cleaning solution is higher than that of the intermediate layer 2 in the cleaning solution.

[0049] In this preferred embodiment, the preset direction is vertical, meaning the isolation layer 4 separates the intermediate layer 2 into a first layer 21 and a second layer 22 along the vertical direction. The first layer 21 below the isolation layer 4 is connected to the metal layer 1, and the second layer 22 above the isolation layer 4 is connected to the mask layer 3. The isolation layer 4, acting as the physical separating interface of the intermediate layer 2, preferentially and rapidly dissolves in the cleaning solution, forming interlayer voids. This process directly disrupts the overall connection between the mask layer 3 and the metal layer 1. The mask layer 3, originally bound to the isolation layer 4 by the second layer 22, loses its support due to the dissolution of the isolation layer 4 and can separate from the metal layer 1 under minimal external force (such as solution flow or slight vibration), achieving rapid peeling of the mask layer 3. Compared to traditional peeling methods relying on dry etching or strong chemical corrosion, this process requires no complex equipment or stringent reaction conditions; it can be completed simply through solution immersion, reducing peeling time to minutes and significantly improving process efficiency.

[0050] See Figures 3 to 5 As shown, the remaining first layer 21 is in direct contact with the metal layer 1, and it swells in the cleaning solution due to the penetration of solvent molecules. This swelling effect has two key effects: First, the swelling weakens the intermolecular forces of poly(3,4-ethylenedioxythiophene), changing its structure from dense to porous, thus reducing the physical adsorption force with the surface of the metal layer 1. Second, the internal stress generated by the swelling is transmitted to the interface through the voids formed after the isolation layer 4 dissolves, further weakening the bonding strength between the first layer 21 and the metal layer 1. The rapid dissolution of the isolation layer 4 provides a buffer space for the swelling of poly(3,4-ethylenedioxythiophene), preventing the swelling stress from being blocked by the upper isolation layer 4 or the mask layer 3, ensuring that the swelling effect can be concentrated on the interface of the metal layer 1, accelerating the attenuation of adhesion. After the isolation layer 4 dissolves and the mask layer 3 peels off, the remaining poly(3,4-ethylenedioxythiophene) develops initial cracks under the stress of solution flow or swelling. Because poly(3,4-ethylenedioxythiophene) is inherently brittle, these initial cracks rapidly extend along the stress concentration direction (such as at the interface with metal layer 1), eventually causing the first layer 21 to shatter completely. Crack propagation breaks down the originally continuous poly(3,4-ethylenedioxythiophene) layer into fine fragments, significantly reducing the contact area with the surface of metal layer 1 and further decreasing adhesion. Ultimately, these fragments can be completely removed from the surface of metal layer 1 through simple cleaning (such as ultrasonic treatment), achieving residue-free removal of all capping layers above metal layer 1.

[0051] The entire peeling process is dominated by a synergistic mechanism of dissolution of the isolation layer 4, swelling of poly(3,4-ethylenedioxythiophene), and crack propagation, avoiding scratches on the metal layer 1 caused by traditional physical peeling or chemical damage to the metal layer 1 caused by strong corrosive etching. It should be noted that the selective dissolution of the isolation layer 4 is only directed at itself and does not react with the metal layer 1; the swelling and crack propagation of poly(3,4-ethylenedioxythiophene) are changes in the material's own structure and will not cause corrosion to the surface of the metal layer; finally, the peeling is achieved by removing the fragments with the solution, without mechanical contact.

[0052] In this preferred embodiment, the isolation layer 4 triggers delamination through rapid dissolution. Combined with the swelling characteristics of poly(3,4-ethylenedioxythiophene) in the cleaning solution and the stress-induced crack propagation effect, a highly efficient, gentle, and non-destructive peeling mechanism is formed. This not only achieves rapid separation between the mask layer 3 and the intermediate layer 2, but also significantly reduces the adhesion between the intermediate layer 2 and the metal layer 1 through the synergistic effect of material properties. Ultimately, it achieves complete peeling of all capping layers above the metal layer 1, improving process efficiency while maximizing the protection of the structural integrity of the metal layer 1. This is particularly suitable for semiconductor device manufacturing scenarios with extremely high surface precision requirements.

[0053] In a preferred embodiment of the present invention, the material of the isolation layer 4 is at least one of polyvinylpyrrolidone (PVP), polyvinyl alcohol (PVA), and hydroxypropyl methylcellulose (HPMC).

[0054] PVP, PVA, and HPMC are all highly polar polymers with hydrophilic groups such as hydroxyl and amide groups in their molecular structure, exhibiting extremely high dissolution rates in cleaning solutions (such as water and ethanol). Compared to the conjugated polymer structure of the intermediate layer 2, poly(3,4-ethylenedioxythiophene), which has weaker polarity and is prone to swelling and slow dissolution in polar solvents, these three materials can dissolve rapidly within seconds to tens of seconds, forming clear interlayer voids and providing an instantaneous triggering mechanism for the peeling of mask layer 3.

[0055] Furthermore, the PVP, PVA, and HPMC in this preferred embodiment all possess excellent film-forming capabilities, and can form dense films with controllable thickness at the nanometer to micrometer level through processes such as spin coating and inkjet printing, ensuring effective isolation of the intermediate layer 2. The polar groups in the molecular chain of the isolation layer 4 can form weak hydrogen bond interactions with the surface of poly(3,4-ethylenedioxythiophene), which not only ensures good adhesion between the isolation layer 4 and the upper and lower poly(3,4-ethylenedioxythiophene) layers, preventing detachment during manufacturing, but also avoids the formation of strong chemical bonds, ensuring thorough interfacial separation during subsequent dissolution.

[0056] Meanwhile, the rapid dissolution characteristics of PVP, PVA, and HPMC in this preferred embodiment can synergize with the swelling effect of poly(3,4-ethylenedioxythiophene) in the cleaning solution, creating a time difference. That is, the isolation layer 4 dissolves before the intermediate layer 2 swells significantly, and the resulting interlayer voids provide ample space for the volume expansion of the remaining first layer 21, avoiding stress offset due to space constraints. The residual cleaning solution after dissolution can further promote the swelling of the first layer 21, significantly increasing the internal stress at the interface between the first layer 21 and the metal layer 1, and accelerating the attenuation of the adhesion between the first layer 21 and the metal layer 1. Compared to other materials, such as hydrophobic polymers, these materials leave no residual solute after dissolution, do not block voids or inhibit the swelling of the first layer 21, and ensure maximum stress transfer efficiency.

[0057] PVP, PVA, and HPMC are all biocompatible materials and can be completely dissolved in the cleaning solution into small molecules or ions, leaving no solid residue. For semiconductor devices requiring biocompatibility, such as implantable sensors and biochips, this avoids biotoxicity caused by residual isolation layer 4. The dissolved products are easily and thoroughly removed by simple cleaning, avoiding contamination of the metal layer 1 surface and ensuring the reliability of subsequent device processing.

[0058] Compared to inorganic insulating materials (such as silicon dioxide and silicon nitride), PVP, PVA, and HPMC have significant cost advantages. Their raw materials are inexpensive, and they do not require complex processes such as vacuum deposition and high-temperature annealing. Large-area fabrication can be achieved through solution processing, significantly reducing mass production costs. Furthermore, they are highly compatible with existing semiconductor wet processes, allowing integration without modifying production lines and shortening the technology deployment cycle.

[0059] In summary, selecting at least one of polyvinylpyrrolidone, polyvinyl alcohol, and hydroxypropyl methylcellulose as the material for the isolation layer 4 can enhance the rapid peeling mechanism through its high polarity and high solubility, while ensuring the stability and safety of the stacked structure through its film-forming properties and compatibility. At the same time, it takes into account cost and process adaptability, which is a precise response to the core requirement of low-damage and efficient peeling. It is especially suitable for scenarios with strict material compatibility requirements, such as flexible electronics and biomedical semiconductors.

[0060] In a preferred embodiment of the present invention, the cleaning solution is a polar solvent.

[0061] Specifically, the polar solvents include water, ethanol, acetone, ethylene glycol, weak acids, weak bases, oxidizing reagents, reducing reagents, and organic solvents.

[0062] By setting the cleaning solution to a polar solvent, it can achieve a precise match with the material properties of the isolation layer 4 and the intermediate layer 2, significantly improving the peeling efficiency and selectivity. The specific beneficial effects are as follows:

[0063] 1) Accelerates the dissolution of the isolation layer 4, triggering rapid peeling. The isolation layer 4 is made of polar polymers, rich in hydrophilic groups such as hydroxyl and amide groups, which can rapidly interact with the polar cleaning solution through hydrogen bonding. For example, protic polar solvents such as water and ethanol can quickly penetrate into the molecular chains of the isolation layer 4, disrupting the intermolecular interactions and causing the isolation layer 4 to dissolve within seconds to minutes; polar aprotic solvents such as acetone and ethylene glycol can bind to the molecules of the isolation layer 4 through dipole-dipole interactions, also efficiently promoting its dissolution. This polarity matching ensures that the isolation layer 4 dissolves preferentially over the intermediate layer 2 and the metal layer 1, providing an instantaneous triggering mechanism for the peeling of the mask layer 3, avoiding the problem of slow or even non-dissolving isolation layer 4 in traditional non-polar solvents.

[0064] 2) Inducing PEDOT swelling and enhancing interlayer separation. Although the PEDOT in the intermediate layer 2 is a conjugated polymer, its molecular chain still contains a small number of polar groups, such as sulfonate groups, which will swell in polar solvents due to solvation. See also Figure 4 As shown, polar solvent molecules (such as water and ethanol) in the cleaning solution can penetrate the molecular stacking structure of PEDOT, increasing the interchain spacing and macroscopically manifesting as volume expansion. The internal stress generated by swelling concentrates at the interface between PEDOT and metal layer 1, weakening the adhesion between them and creating conditions for subsequent crack propagation and peeling of PEDOT. Compared to non-polar solvents (such as toluene and cyclohexane), which cannot effectively swell PEDOT, polar solvents can maximize their swelling-stress effect, accelerating the separation of the capping layer above metal layer 1.

[0065] 3) A wide selection of solvents to meet diverse process requirements. The different properties of solvents with different polarities can meet the stripping needs of different scenarios, for example:

[0066] Water and ethanol: Non-corrosive, suitable for scenarios where strict protection is required for metal layer 1 (such as copper or aluminum) and substrate 7 to avoid chemical damage;

[0067] Acetone and ethylene glycol: have strong dissolving power and controllable volatility. The dissolution rate of the isolation layer 4 can be controlled by adjusting the concentration, which can meet the differentiated peeling requirements of isolation layers 4 with different thicknesses.

[0068] Weak acids (such as dilute acetic acid) and weak bases (such as ammonia): By slightly adjusting the pH value, the dissociation of polar groups in the isolation layer 4 can be accelerated, further improving the dissolution efficiency, while avoiding significant corrosion of PEDOT and metal layer 1.

[0069] Oxidizing / reducing agents (such as hydrogen peroxide, ascorbic acid): can be used to treat oxide films (such as copper rust) on the surface of metal layer 1, cleaning the metal surface while peeling off the coating, reducing subsequent processing steps;

[0070] Mixed organic solvents: By compounding (such as ethanol-water mixture), the polarity can be adjusted to achieve a precise balance between the dissolution rate of the isolation layer 4 and the swelling degree of PEDOT.

[0071] 4) Improved stripping selectivity and reduced residue risk. Polar solvents exhibit high selectivity in their effect on each layer, rapidly dissolving only the isolation layer 4 and inducing PEDOT swelling in the intermediate layer 2. They have no dissolving or corrosive effect on the metal layer 1 (such as gold, silver, or copper), which can be avoided unless a highly corrosive polar reagent is used. The impact on the mask layer 3 is controllable; inorganic mask layers such as SiN are completely insoluble in polar solvents, ensuring that the stripping process targets only the target layer. This selectivity minimizes residue on the surface of the metal layers after stripping, reducing the difficulty of subsequent cleaning and ensuring the stability of the device's electrical performance.

[0072] In summary, by using polar solvents as cleaning fluids, and through a triple mechanism of polarity matching to accelerate the dissolution of the isolation layer, solvation-induced swelling of PEDOT, and diversified selection to adapt to process requirements, efficient and selective peeling of the capping layer above metal layer 1 is achieved, while also protecting each functional layer. This is a precise response to the core requirements of rapid peeling and low damage, and is especially suitable for semiconductor device manufacturing scenarios such as flexible electronics and biosensors with stringent material compatibility requirements.

[0073] In a preferred embodiment of the present invention, the material of the metal layer 1 includes at least one of aluminum, copper, silver, gold, aluminum-copper alloy and titanium-tungsten alloy.

[0074] The material of the mask layer 3 includes at least one of titanium nitride, tantalum nitride, silicon nitride, and silicon dioxide.

[0075] The metal layer 1 is selected from at least one of precious metals such as aluminum, copper, silver, and gold, as well as aluminum-copper alloys and titanium-tungsten alloys, forming a stable interface combination with nitrides such as titanium nitride and tantalum nitride, or compounds such as silicon nitride and silicon dioxide in the mask layer 3. These metals possess good electrical conductivity and ductility, while the mask layer 3 material exhibits high hardness, corrosion resistance, and chemical stability; their physicochemical properties are complementary. The metal layer 1 provides the electrical or mechanical basis for the structure, while the mask layer 3 can serve as a protective or insulating layer. Together with the intermediate layer 2, it achieves efficient stacking of the metal-functional intermediate layer-functional mask layer, meeting performance requirements in different scenarios.

[0076] The selected metal layer 1 materials are all commonly used substrates in the field of micro-nano fabrication, with strong compatibility with existing deposition (and etching) processes, and can be directly integrated into mature production lines. The titanium nitride, silicon dioxide, and other materials in the mask layer 3 are also standard mask materials in semiconductor and precision manufacturing. Their interfacial bonding with the intermediate layer 2 is moderate, ensuring structural stability during stacking and allowing them to be peeled off with the intermediate layer 2 under the action of cleaning solution, avoiding mask layer 3 residue or damage to metal layer 1. In addition, the titanium-tungsten alloy and other metal materials also have excellent high-temperature resistance, which can adapt to possible subsequent high-temperature processing processes, expanding the process applicability of the overall structure.

[0077] Different metal layer 1 materials can be tailored to specific functional requirements: for example, gold and silver can be used in high-frequency conductive scenarios, aluminum-copper alloys balance cost and conductivity for large-scale wiring, and titanium-tungsten alloys, due to their excellent barrier layer properties, are suitable for structures requiring diffusion isolation. The choice of mask layer 3 also has functional orientation: titanium nitride can be used as an anti-reflection layer or a diffusion barrier layer, silicon dioxide is suitable for insulating scenarios, and silicon nitride, due to its high density, is suitable as a protective layer. This diverse combination of materials allows the metal stacked film structure to flexibly adapt to the differentiated needs of various fields such as semiconductor devices, flexible electronics, and precision sensors, significantly improving the universality and practicality of the technical solution.

[0078] In a preferred embodiment of the present invention, the thickness of the intermediate layer 2 is 80nm~2000nm.

[0079] The intermediate layer 2 needs to form a continuous support between the metal layer 1 and the mask layer 3. If the thickness is less than 80nm, it is easy to fail to effectively isolate the metal layer 1 and the mask layer 3 due to film discontinuity and too many pinhole defects, which may cause interlayer diffusion. In addition, if the thickness is too small, it will lead to insufficient mechanical strength. It is easy to break under stress during dry etching, cleaning and other processes, and lose its supporting function for the mask layer 3.

[0080] PEDOT, or intermediate layer 2, requires a certain degree of volume expansion in the solvent to generate internal stress. A thickness of 80 nm ensures that a sufficient stress gradient is formed after swelling, providing initial impetus for subsequent peeling. If the thickness is too thin, the swelling amount is insufficient, and the stress is difficult to overcome the interfacial adhesion between metal layer 1 and intermediate layer 2.

[0081] If the thickness of the intermediate layer 2 exceeds 2000 nm, it will lead to two problems. First, it will slow down the swelling rate, prolong the solvent penetration path in the thick film, and significantly increase the time for PEDOT to reach the critical stress, resulting in a decrease in peeling efficiency. Second, it will cause stress dispersion. An excessively thick intermediate layer 2 will cause the stress generated by swelling to be dispersed within the layer, making it difficult to concentrate on the interface of the metal layer 1. This may result in incomplete peeling, leaving some PEDOT on the surface of the metal layer 1, which will affect the performance of subsequent devices.

[0082] It should be noted that the thickness of intermediate layer 2 can be adjusted by controlling the spin coating speed, and the actual thickness of intermediate layer 2 can be selected according to the manufacturing process. Different stages of semiconductor manufacturing (such as front-end photolithography, mid-end etching, and back-end packaging) have different requirements for the thickness of intermediate layer 2. For example, in the photolithography pattern transfer stage, to avoid light absorption deviation caused by excessive thickness of intermediate layer 2, a thinner intermediate layer 2, such as 80nm~500nm, can be obtained by increasing the spin coating speed; while in the mechanical buffer scenario between metal layer 1 and mask layer 3, the thickness of intermediate layer 2 needs to be increased to improve support capacity, and in this case, the spin coating speed can be reduced to obtain a thicker film of 500nm~2000nm. This on-demand adjustment feature allows intermediate layer 2 to be seamlessly integrated into diverse process flows without the need to develop additional special materials or equipment.

[0083] In one embodiment, the present invention provides a method for preparing an easily peelable metal stacked film structure, comprising:

[0084] An intermediate layer 2 is deposited on one side surface of the metal layer 1 and cured by heating after deposition. The intermediate layer 2 is made of poly(3,4-ethylenedioxythiophene)-polystyrene sulfonic acid.

[0085] A mask layer 3 is deposited on the intermediate layer 2 to obtain the above-described easily peelable metal stacked film structure.

[0086] The intermediate layer 2 and mask layer 3 are formed using a deposition process, which conforms to the mature technical path in the field of micro-nano manufacturing and facilitates precise control of film thickness and uniformity. The heating and curing step after the deposition of intermediate layer 2 promotes the cross-linking and stable arrangement of poly(3,4-ethylenedioxythiophene)-polystyrene sulfonic acid (PEDOT-PSS) molecular chains. This not only enhances its interfacial adhesion with the metal layer, preventing it from falling off during stacking, but also retains its removable properties in a specific cleaning solution, achieving a balance between stable curing and subsequent peelability.

[0087] The deposition process is highly adaptable to both metal layer 1 and mask layer 3: physical vapor deposition or chemical deposition can be selected according to material characteristics, avoiding damage to the substrate metal caused by high temperature or chemical corrosion. At the same time, the deposition process of PEDOT-PSS is mild and can be carried out using low-temperature processes such as spin coating and inkjet printing. It will not react adversely with metal layer 1, nor will it affect the deposition quality of subsequent mask layer 3, ensuring the interface stability of the three-layer structure.

[0088] This preparation method regulates the physical state of PEDOT-PSS through a curing process. This ensures that PEDOT-PSS serves as the structural support for the intermediate layer 2, connecting the metal layer 1 and the mask layer 3. Simultaneously, moderate cross-linking of the molecular chains preserves its swelling or dissolving ability in the cleaning solution, laying the foundation for subsequent peeling steps. When peeling is required, the cleaning solution quickly penetrates and disrupts the intermolecular forces of PEDOT-PSS, allowing the mask layer 3 to detach smoothly. This method resolves the contradiction of traditional adhesives: strong adhesion leads to difficult peeling, while easy peeling results in insufficient adhesion.

[0089] In a preferred embodiment of the present invention, the temperature for heating and curing is set to 45°C to 55°C, and the time is set to 90s to 150s.

[0090] The conjugated structure of the intermediate PEDOT layer is prone to oxidation or chain breakage at high temperatures, leading to a decrease in conductivity and mechanical properties. The isolation layer 4 is a polymer material, which may undergo thermal decomposition or glass transition above 60°C, damaging its film-forming properties. The medium-low temperature range of 45°C to 55°C can avoid the above problems and ensure the chemical structure stability of the intermediate layer 2 and the isolation layer 4.

[0091] Furthermore, metal layer 1 may undergo surface oxidation or grain growth at high temperatures. This temperature range is far below the oxidation threshold of metals, thus protecting the conductivity and interface integrity of metal layer 1.

[0092] Meanwhile, the intermediate layer 2 and the isolation layer 4 have a small amount of solvent remaining after spin coating. The solvent can be evaporated by gentle heating at 45℃~55℃, which makes the film structure denser. At the same time, it avoids the rapid boiling of solvent due to high temperature, which would generate bubbles and damage the continuity of the film.

[0093] Heating time of 90s to 150s ensures that residual solvent in the film layer evaporates fully, allowing the intermediate PEDOT layer to form a stable molecular stacking structure, improving mechanical strength and solvent resistance, while also enhancing the adhesion between the isolation layer 4 and the upper and lower layers, preventing it from falling off in subsequent processes.

[0094] For example, the temperature for heat curing is set to 50°C and the time is set to 120 seconds.

[0095] In one embodiment, the present invention provides a semiconductor device comprising the above-described easily peelable metal stacked film structure.

[0096] The easily peelable metal stacked film structure of this invention includes a metal layer 1, an intermediate layer 2, and a mask layer 3 stacked sequentially along a predetermined direction. The intermediate layer 2 is made of poly(3,4-ethylenedioxythiophene)-polystyrene sulfonic acid. On one hand, the intermediate layer 2 ensures good bonding with both the metal layer 1 and the mask layer 3, while also being dissolved and removed under the action of a cleaning solution. This allows the mask layer 3 to detach smoothly from the metal layer, avoiding damage to the metal layer 1, thus achieving the effect of removing the mask layer 3 without damage. On the other hand, the poly(3,4-ethylenedioxythiophene)-polystyrene sulfonic acid meets the requirements of dry etching. During etching, after the molecular chains of the intermediate layer 2 break or recombine, a protective polymer film forms on the sidewalls, effectively inhibiting lateral etching and ensuring that the intermediate layer 2 forms a vertical cross-sectional profile, thus guaranteeing the structural accuracy and performance stability of the semiconductor device pattern transfer.

[0097] The above embodiments are merely preferred embodiments provided to fully illustrate the present invention, and the scope of protection of the present invention is not limited thereto. Equivalent substitutions or modifications made by those skilled in the art based on the present invention are all within the scope of protection of the present invention.

Claims

1. An easily peelable metal stacked film layer structure, characterized by, The metal layer, the intermediate layer and the mask layer are stacked in sequence along a preset direction; The material of the intermediate layer is poly(3,4-ethylenedioxythiophene)-polystyrene sulfonic acid; When the mask layer on the metal layer is peeled off, the intermediate layer is removed by dissolving in a cleaning liquid, so that the mask layer is separated from the metal layer.

2. The readily peelable metal stack film layer structure of claim 1, wherein: Further comprising an isolation layer formed in the intermediate layer, the isolation layer separates the intermediate layer into a first layer and a second layer along a preset direction, the first layer is connected with the metal layer, and the second layer is connected with the mask layer; The dissolution speed of the isolation layer in the cleaning liquid is higher than that of the intermediate layer.

3. The readily peelable metal stack film layer structure of claim 2, wherein: The material of the isolation layer is at least one of polyvinylpyrrolidone, polyvinyl alcohol and hydroxypropyl methyl cellulose.

4. The readily peelable metal stack film layer structure according to any one of claims 1-3, wherein: The cleaning liquid is a polar solvent.

5. The readily peelable metal stack film layer structure of claim 1, wherein: The material of the metal layer includes at least one of aluminum, copper, silver, gold, aluminum-copper alloy and titanium-tungsten alloy.

6. The readily peelable metal stack film layer structure of claim 1, wherein: The material of the mask layer includes at least one of titanium nitride, tantalum nitride, silicon nitride and silicon dioxide.

7. The readily peelable metal stack film layer structure of claim 1, wherein: The thickness of the intermediate layer is 80nm-2000nm.

8. A method of producing an easily peelable metal stacked film layer structure, characterized by, The metal layer, the intermediate layer and the mask layer are stacked in sequence along a preset direction; An intermediate layer is deposited on one side surface of the metal layer, and the material of the intermediate layer is poly(3,4-ethylenedioxythiophene)-polystyrene sulfonic acid; The intermediate layer is heated and solidified after deposition; A mask layer is deposited on the intermediate layer to obtain the easily peeled metal stacked film layer structure according to any one of claims 1-7.

9. The method of claim 8, wherein: The heating and solidification temperature is set to 45-55℃, and the time is set to 90-150s.

10. A semiconductor device, characterized by: The easily peeled metal stacked film layer structure according to any one of claims 1-7.

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