Etching method of HgTe colloidal quantum dot film
By using high-viscosity solvents and pre-wetting techniques, combined with etching methods using hydrobromic acid and hydrogen peroxide, the diffusion and damage problems in the etching process of HgTe colloidal quantum dot films were solved, achieving high-precision, low-damage etching results and improving the stability of the films and device performance.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- SHAOXIN LABORATORY
- Filing Date
- 2025-12-10
- Publication Date
- 2026-04-21
AI Technical Summary
In the existing technology, the etching method for HgTe colloidal quantum dot films has problems such as excessively rapid diffusion of etching solution, difficulty in controlling the etching rate, uncontrollable etching process, and damage to surface ligands caused by physical bombardment, which affect device performance.
High-viscosity solvents such as ethylene glycol or propylene glycol are used as the base solvent, combined with hydrobromic acid and hydrogen peroxide. A liquid barrier is formed through pre-wetting to control the diffusion rate of the etching solution, and a low surface tension solvent is used to terminate the etching reaction, thereby achieving a precisely controlled etching process.
This achieves a high-precision, low-damage etching process, avoiding deep corrosion and surface damage from the etching solution, and improving the stability of the thin film and the performance of the device.
Smart Images
Figure CN121908671A_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of semiconductor optoelectronic device manufacturing, and in particular to an etching method for HgTe colloidal quantum dot thin films. Background Technology
[0002] This invention relates to the field of semiconductor optoelectronic device manufacturing, particularly wet etching and patterning techniques in the fabrication of infrared colloidal quantum dot (CQD) focal plane array devices. In recent years, with the widespread application of infrared detectors and imaging equipment, infrared colloidal quantum dots (such as HgTe) have become ideal low-cost infrared detection materials due to their tunable infrared absorption characteristics. Especially in the fabrication of infrared detectors, the absorption characteristics of HgTe colloidal quantum dots can be adjusted as needed over a wide wavelength range; therefore, HgTe quantum dot films are commonly used as photodetector layers in device fabrication. To achieve high-performance optoelectronic devices, these quantum dot films often need to be patterned to fabricate focal plane array devices with high spatial resolution. However, since HgTe colloidal quantum dot films are typically deposited by spin coating or spraying, these films often have a porous structure formed by the accumulation of nanoparticles, which presents considerable challenges to etching and patterning processes.
[0003] In existing technologies, wet etching is commonly used for thin film patterning. However, traditional wet etching solutions (such as bromine-methanol systems) have significant drawbacks. Due to the low viscosity of methanol, the bromine-methanol solution rapidly penetrates into the interior of the HgTe film through capillary action upon contact. Because of its extremely low viscosity, the etching solution quickly diffuses and penetrates deep into the film, causing the film layer to be hollowed out or even completely peeled off, thus failing to form precise vertical sidewalls. Furthermore, the etching rate of traditional wet etching is typically very fast (milliseconds), making precise control difficult and resulting in unavoidable damage during the etching process, making it difficult to achieve the required surface precision. This phenomenon of rapid solvent diffusion and excessively fast etching rates is particularly severe in porous HgTe colloidal quantum dot films, causing the etching process to become uncontrollable and affecting device performance.
[0004] Furthermore, while dry etching offers relatively precise etching control, its drawbacks are also significant. Dry etching techniques require the use of plasma or other high-energy physical bombardment methods, achieving etching through the impact of high-speed particles. Although this method can control etching precision well in some applications, its impact on surface-sensitive materials such as HgTe colloidal quantum dots cannot be ignored. Physical bombardment can damage the ligands on the quantum dot surface and even cause mercury loss, thereby altering the electronic structure of the quantum dots. Mercury loss leads to a decrease in the material's photoelectric properties, increases dark current, and thus severely affects the detector's sensitivity. Therefore, dry etching often fails to achieve ideal results when processing such materials.
[0005] To address the aforementioned issues, this invention proposes a novel wet etching method, aiming to provide a wet etching system that effectively controls the diffusion rate, protects quantum dot surface ligands, and offers a mild and controllable etching rate. By employing a high-viscosity solvent (such as ethylene glycol or propylene glycol) as the base solvent, and combining it with reaction components such as hydrobromic acid (HBr) and hydrogen peroxide (H2O2), diffusion-limited etching of HgTe colloidal quantum dot films has been successfully achieved. By adjusting the viscosity of the solution and the concentration of the reaction components, this invention can significantly reduce the diffusion rate of the etching solution, allowing the etching reaction to be precisely controlled on the outer surface of the film, avoiding solvent penetration and deep corrosion of the film's interior by the etching solution. Furthermore, this novel etching solution effectively avoids the adverse effects of rapid solvent penetration and excessively fast etching rates in traditional wet etching, while also preventing mercury loss and surface ligand damage caused by high-energy bombardment in dry etching. Summary of the Invention
[0006] To address the aforementioned technical problems, this application provides an etching method for HgTe colloidal quantum dot films.
[0007] The etching method for HgTe colloidal quantum dot thin films provided in this application adopts the following technical solution: An etching method for HgTe colloidal quantum dot films, characterized in that the etching method includes the following steps: Step 1: Prepare a high-viscosity etching solution, which contains ethylene glycol or propylene glycol as a base solvent and hydrobromic acid (HBr) and hydrogen peroxide (H2O2) as the main reaction components; Step 2: The HgTe colloidal quantum dot film is pre-wetted with solvent by initially immersing it in pure ethylene glycol or propylene glycol to form a liquid barrier; Step 3: Place the pre-wetted film into the etching solution for diffusion-limited etching to control the diffusion rate of bromide ions and oxidant in the etching solution; Step 4: Quickly replace the etching solution with a low surface tension solvent miscible with ethylene glycol (such as isopropanol or acetonitrile) to terminate the etching reaction and clean the film.
[0008] By employing the above technical solution, high-viscosity ethylene glycol or propylene glycol is used as the base solvent. By adjusting the viscosity of the etching solution, the diffusion rate of the reactants is significantly reduced, ensuring precise control of the etching process. The use of high-viscosity solvents prevents the solvent from penetrating too quickly into the film layer, preventing deep corrosion and overall peeling of the film layer. By forming a liquid barrier on the film surface, the diffusion of the solvent is effectively limited, allowing the etching reaction to occur only in the outer region of the film, achieving high-precision patterned etching and avoiding unnecessary damage. In the pre-wetting step, pure ethylene glycol or propylene glycol can penetrate into the nanopores of the film, forming a protective barrier, reducing the excessive diffusion of oxidants, and avoiding the excessive corrosion phenomenon in traditional wet etching. The use of a solvent with low surface tension to quickly replace the etching solution promptly terminates the etching reaction, preventing over-etching and film damage, while also removing reaction products, ensuring the cleanliness and precision of the film surface.
[0009] Optionally, the concentration of hydrobromic acid (HBr) in the etching solution is 40%-48%, the concentration of hydrogen peroxide (H2O2) is 30%, and the volume ratio of the etching solution is: the mixture of hydrobromic acid and hydrogen peroxide is added to pure ethylene glycol or propylene glycol at a volume ratio of 1:50 to 1:200 to form the high viscosity etching solution.
[0010] By employing the above technical solution and precisely adjusting the concentration and volume ratio of hydrobromic acid (HBr) and hydrogen peroxide (H2O2), the reaction rate and control precision of the etching solution can be optimized. Hydrobromic acid can effectively cleave the Hg-Te bond, while hydrogen peroxide promotes the oxidation reaction of Te. The synergistic effect of the two achieves mild etching of HgTe colloidal quantum dot films. High-viscosity ethylene glycol or propylene glycol, as solvents, effectively restricts solute diffusion, ensuring that the etching reaction only occurs on the film surface, avoiding internal damage, and achieving precise patterned etching.
[0011] Optionally, the viscosity of the ethylene glycol or propylene glycol is 16 cP (ethylene glycol) or 13 cP (propylene glycol). Its high viscosity significantly reduces the diffusion rate of the reaction solute and controls the rate of the etching reaction.
[0012] By adopting the above technical solution, the high viscosity of ethylene glycol or propylene glycol significantly reduces the diffusion rate of the reaction solute, effectively controlling the etching reaction rate. The low diffusion rate ensures that when the etching solution contacts the HgTe colloidal quantum dot film, the reaction occurs only on the surface of the film, avoiding excessive penetration and deep corrosion. This makes the etching process more gentle and controllable, reduces film damage and unnecessary side reactions, achieves high-precision patterned etching, and improves the quality and stability of the film.
[0013] Optionally, the solvent pre-wetting step involves immersing the HgTe colloidal quantum dot film in pure ethylene glycol, allowing the ethylene glycol to penetrate into the nanopores of the film and form a liquid barrier layer, so that the etching reaction occurs only on the outermost surface of the film.
[0014] By adopting the above technical solution, the liquid barrier layer effectively restricts the diffusion of the etching solution, ensuring that the etching reaction only occurs on the outermost surface of the film, avoiding the etching solution from penetrating into the film and causing unnecessary deep corrosion, ensuring precise control of the etching process, improving the quality of film patterning, and reducing film damage.
[0015] Optionally, the pre-wetting step serves to control the diffusion rate of oxidant molecules in the etching solution by forming a liquid barrier on the film surface, thereby forcibly limiting the reaction to occur only in the outer region of the film.
[0016] By adopting the above technical solution, the liquid barrier effectively restricts the diffusion of oxidant, and the forced etching reaction only occurs in the outer region of the film, avoiding over-etching and deep corrosion, ensuring the accuracy of etching and surface quality, making the patterning of the film more precise, reducing film damage, and improving the performance and stability of the device.
[0017] Optionally, the diffusion-limited etching step is achieved by controlling the diffusion rate of bromide ions in the etching solution. The high-viscosity etching solution significantly slows down the diffusion of bromine molecules through the Stokes-Einstein equation, so that the etching reaction is carried out within a controlled range.
[0018] By adopting the above technical solution, the high-viscosity etching solution significantly slows down the diffusion of bromide ions. By utilizing the Stokes-Einstein equation, the movement speed of bromine molecules is reduced, ensuring that the etching reaction is carried out within a controllable range. This effectively avoids excessively fast etching reactions, reduces excessive damage to the film layer, ensures high-precision etching of the thin film, and improves the accuracy and surface quality of patterned etching.
[0019] Optionally, during the etching process, ethylene glycol not only reduces the diffusion rate of bromide ions, but also binds to mercury ions through a complexation reaction, preventing mercury ions from redepositing on the surface of the quantum dot film.
[0020] By adopting the above technical solution, secondary deposition of mercury ions is effectively avoided, the uniformity and stability of the film are maintained, surface contamination or damage is prevented, the quality of the film is improved, the etching process is made mild and low-damage, and the stability of device performance is guaranteed.
[0021] Optionally, the hydrogen peroxide (H2O2) acts as an oxidant in the etching solution, which can promote the oxidation reaction of Te (tellurium) atoms and generate tiny oxygen bubbles, further promoting the renewal of the film reaction interface.
[0022] By adopting the above technical solution, the generation of oxygen bubbles helps to continuously renew the reaction interface of the film layer, avoid local stagnation in the reaction process, and through this mechanism, the etching reaction can continue, ensuring the uniformity and etching accuracy of the film, avoiding irregular etching marks or damage, and improving the surface quality and patterning accuracy of the film.
[0023] Optionally, the termination reaction and cleaning steps involve rapidly replacing the etching solution with a low surface tension solvent such as isopropanol or acetonitrile to stop the etching reaction and remove the reacted products, thereby avoiding over-etching and damage to the film. The hydrobromic acid (HBr) and hydrogen peroxide (H2O2) in the etching solution work synergistically. Hydrobromic acid mainly breaks the Hg-Te bond, while hydrogen peroxide promotes the oxidation of Te. The combined effect of the two achieves a gentle yet precise etching of the HgTe colloidal quantum dot film. The etching method is particularly suitable for fabricating HgTe colloidal quantum dot thin film devices that require high-precision patterning, such as infrared detectors and infrared imaging devices.
[0024] By adopting the above technical solution, the etching process is precisely controlled and the integrity of the film surface is maintained. Hydrobromic acid and hydrogen peroxide work synergistically. Hydrobromic acid breaks the Hg-Te bond, while hydrogen peroxide promotes the oxidation of Te. Together, they achieve gentle and precise etching of HgTe colloidal quantum dot films.
[0025] Optionally, the method can effectively avoid the problems of internal film collapse and lateral drilling caused by excessively rapid solvent diffusion in traditional wet etching, thereby obtaining high-precision, low-damage HgTe colloidal quantum dot thin film patterning. The preparation of the etching solution and the reaction control conditions can be flexibly optimized by adjusting factors such as solvent type, hydrobromic acid concentration, hydrogen peroxide concentration and etching time to meet the etching requirements of HgTe colloidal quantum dot films with different thicknesses and porosities. The high-viscosity etching solution can effectively protect the surface ligands of quantum dots, prevent the loss of surface ligands or damage to quantum dots due to excessive etching, thereby improving the stability of the film and the performance of the device.
[0026] By adopting the above technical solution, high-precision and low-damage HgTe colloidal quantum dot film patterning can be achieved. By flexibly adjusting parameters such as solvent type, hydrobromic acid concentration, hydrogen peroxide concentration and etching time, the etching requirements of films with different thicknesses and porosities can be met. The high-viscosity etching solution effectively protects the ligands on the quantum dot surface, prevents the loss of surface ligands and quantum dot damage caused by excessive etching, and improves the stability of the film and the performance of the device.
[0027] In summary, this application includes at least one of the following beneficial technical effects: 1. By reducing the etching rate, the problem of "collapse upon contact" of traditional strong oxidants is solved, achieving extremely high controllability.
[0028] 2. The dual mechanism of "pre-wetting + high viscosity" effectively prevents the uncontrolled diffusion of etchant into the porous film layer, thus protecting the internal structure.
[0029] 3. Compared to physical bombardment, chemical etching causes less surface lattice damage, which is beneficial for subsequent electrode deposition and ohmic contact formation.
[0030] 4. By using high-viscosity ethylene glycol or propylene glycol as the base solvent, the diffusion rate of the reactants is significantly reduced, ensuring precise control of the etching process, effectively avoiding internal film collapse and lateral drilling, and obtaining high-precision, low-damage HgTe colloidal quantum dot thin film patterning.
[0031] 5. The use of high-viscosity solvents prevents the solvent from penetrating too quickly into the film, thus preventing deep corrosion and overall peeling of the film. Solvent pre-wetting forms a liquid barrier, further ensuring that the etching reaction occurs only in the outer layer of the film, reducing film damage.
[0032] 6. By optimizing the concentration and volume ratio of hydrobromic acid (HBr) to hydrogen peroxide (H2O2), the reaction rate is controlled, the Hg-Te bond is gently cleaved, and the oxidation of Te is promoted, thus achieving precise patterning etching of HgTe colloidal quantum dot films and avoiding irregular etching marks or damage.
[0033] 7. Termination of Reaction and Cleaning Steps: Use a low surface tension solvent (such as isopropanol or acetonitrile) to quickly replace the etching solution, stop the etching reaction, and remove the reacted products. This prevents over-etching and film damage, ensuring the accuracy and integrity of the film surface.
[0034] 8. High-viscosity etching solution effectively protects the ligands on the quantum dot surface, preventing the loss of surface ligands or damage to quantum dots due to excessive etching, thereby improving the stability of the film and device performance, and extending the service life of the device.
[0035] 9. This method can be flexibly optimized by adjusting factors such as solvent type, hydrobromic acid concentration, hydrogen peroxide concentration and etching time to adapt to the etching requirements of HgTe colloidal quantum dot films with different thicknesses and porosities, ensuring the controllability and efficiency of the etching process. Attached Figure Description
[0036] Figure 1 This is a flowchart of an embodiment of this application.
[0037] Figure 2 This is an optical microscope image of the etched quantum dot film on the interdigitated metal electrode according to an embodiment of this application.
[0038] Figure 3 These are atomic force microscopy data images of the edge and center of the quantum dot film in the embodiments of this application.
[0039] Figure 4 This is an optical microscope image of a HgTe quantum dot thin film that shows significant degradation in an embodiment of this application. Detailed Implementation
[0040] The following is in conjunction with the appendix Figure 1-4 This application will be described in further detail.
[0041] This application discloses an etching method for HgTe colloidal quantum dot thin films. (Refer to...) Figure 1 The etching method includes the following steps: Step 1: Prepare a high-viscosity etching solution, which contains ethylene glycol or propylene glycol as a base solvent and hydrobromic acid (HBr) and hydrogen peroxide (H2O2) as the main reaction components; Step 2: The HgTe colloidal quantum dot film is pre-wetted with solvent by initially immersing it in pure ethylene glycol or propylene glycol to form a liquid barrier; Step 3: Place the pre-wetted film into the etching solution for diffusion-limited etching to control the diffusion rate of bromide ions and oxidant in the etching solution; Step 4: Quickly replace the etching solution with a low surface tension solvent miscible with ethylene glycol (such as isopropanol or acetonitrile) to terminate the etching reaction and clean the film.
[0042] The technical solution uses high-viscosity ethylene glycol or propylene glycol as the base solvent, reducing the solute diffusion rate and effectively controlling the etching reaction rate. This ensures the etching process is conducted within a controllable range. The high-viscosity solvent prevents excessive penetration into the film, avoiding excessive corrosion and overall peeling deep within the film. A solvent pre-wetting step forms a liquid barrier on the surface of the HgTe colloidal quantum dot film, limiting the diffusion of the etching solution and ensuring the etching reaction occurs only in the outermost layer of the film. This guarantees surface cleanliness and avoids deep corrosion and lateral drilling within the film. By precisely adjusting the concentration and volume ratio of hydrobromic acid (HBr) and hydrogen peroxide (H2O2), the reaction rate of the etching solution is optimized, resulting in a gentler etching reaction that avoids over-etching and surface damage. This gently breaks the Hg-Te bonds, effectively promoting the oxidation reaction of Te, and precisely completing the patterning etching without damaging the film. Using a low surface tension solvent to rapidly replace the etching solution terminates the etching reaction and removes the reaction products, avoiding over-etching and damage to the film surface. During the etching process, ethylene glycol or propylene glycol not only reduces the diffusion rate of the solute, but also combines with mercury ions through a complexation reaction, preventing mercury ions from redepositing on the film surface, ensuring the uniformity and stability of the film, avoiding surface contamination or damage, and improving the quality of the film and the stability of the device.
[0043] Example 1 Example 1: HgTe quantum dot etching based on the ethylene glycol-bromine system Experimental materials: Sample to be etched: a 400nm thick mid-wave infrared HgTe colloidal quantum dot film (spin-coated onto a silicon wafer and patterned with photoresist to expose the area to be etched).
[0044] Solvent: Anhydrous ethylene glycol (EG, viscosity approximately 16 cP).
[0045] Oxidizing agent: Elemental bromine ($Br_2$).
[0046] Etching solution preparation: In a glove box or fume hood, dissolve 0.1 mL of elemental bromine in 10 mL of anhydrous ethylene glycol to prepare a stock solution.
[0047] The mother liquor was further diluted with anhydrous ethylene glycol at a volume ratio of 1:50 to obtain the final high-viscosity etching solution.
[0048] Process steps: Pre-wetting: The HgTe thin film sample with photoresist pattern is completely immersed in pure anhydrous ethylene glycol and left to stand for 30 seconds. This step utilizes ethylene glycol to fill the nanopores of the quantum dot film, establishing a diffusion barrier layer.
[0049] Wet etching: While keeping the sample moist, quickly transfer it to the prepared etching solution. Gently agitate at room temperature, and control the etching time to 45 seconds.
[0050] Termination and cleaning: Remove the sample and immediately immerse it in pure isopropanol (IPA) twice for 1 minute each time to remove residual ethylene glycol and reaction products. Finally, dry it with a nitrogen gun.
[0051] 4. Implementation Results: Scanning optical microscopy revealed that the etched mesa edges were clear and neat, with high sidewall verticality. No "bulk etching" phenomenon (i.e., the film interior is hollowed out but the surface remains intact), common in traditional low-viscosity solvent etching, was observed, nor was there any significant film peeling or detachment.
[0052] Example 2 The difference compared to Example 1 is as follows: Solvent: 1,2-Propylene Glycol (PG, viscosity approximately 42 cP, more viscous than ethylene glycol).
[0053] Pre-wetting: Immerse the sample in pure propylene glycol for 60 seconds. Due to the higher viscosity of propylene glycol, the pre-wetting time should be appropriately extended to ensure thorough wetting.
[0054] Cleaning: Use ethanol and isopropanol alternately to clean and remove high-viscosity propylene glycol residue.
[0055] Results: Atomic force microscopy (AFM) tests showed that the RMS roughness of the treated film surface was reduced to below 3 nm.
[0056] Comparative Example 1 To verify the crucial role of high-viscosity solvents in etching accuracy in this invention, a comparative experiment was conducted using traditional low-viscosity organic solvents.
[0057] The difference compared to Example 1 is as follows: Etching solution preparation: Isopropanol (IPA) was selected as the solvent.
[0058] 2. Experimental Results: After immersion in the etching solution, the etching reaction was observed to be extremely rapid and difficult to control. After removing the sample and cleaning to remove the photoresist at the same etching time (45 seconds) as in Example 1, the degradation was obvious when observed under an optical microscope. The remaining thin film area showed pores or discoloration, which damaged the integrity of the material.
[0059] in conclusion: The results of Comparative Example 1 show that, at the same oxidant concentration, precise anisotropic etching cannot be achieved using conventional low-viscosity solvents. The excessively rapid diffusion rate of the low-viscosity solvents leads to severe lateral drilling and film damage.
[0060] In contrast, Example 1 uses the high-viscosity ethylene glycol solvent system proposed in this invention, which significantly suppresses the diffusion rate of reactants and products by utilizing its high viscosity characteristics, thus demonstrating the inventiveness and necessity of the technical solution of this invention.
[0061] Reference Figure 2 , Figure 2 These are optical microscope images. The quantum dot film etched in Example 1 is shown on a metal interdigitated electrode, with clear film edges.
[0062] Reference Figure 3 , Figure 3 These are atomic force microscopy (AFM) images. The quantum dot film in the example shows sharp edges and a uniform atomic-level structure at the edges and center.
[0063] Reference Figure 4 , Figure 4 Optical microscope image. After etching in Comparative Example 1, a significantly degraded HgTe quantum dot film was observed.
[0064] The core protection points of the technical solution are: A wet etching method for protecting an HgTe colloidal quantum dot film includes the following key steps. Solvent system limitations: The etching solution must use a high-viscosity polar solvent (such as ethylene glycol, propylene glycol or glycerol) as the main solvent, rather than a traditional low-viscosity solvent (such as methanol or acetonitrile).
[0065] Pre-wetting process: Before contact with the etching solution, a pretreatment step must be included, in which the thin film is immersed in the same high-viscosity pure solvent to fill the pores and establish a diffusion barrier layer.
[0066] Extremely dilute concentration control: The concentration of the oxidant in the etching solution needs to be controlled at the millimolecular (mM) level (e.g., a volume dilution ratio between 1:50 and 1:200) in order to achieve diffusion restriction in conjunction with the high viscosity solvent.
[0067] The solvent in the technical solution is a polyol solvent, including but not limited to ethylene glycol (EG), propylene glycol (PG), diethylene glycol, glycerol, or mixtures thereof.
[0068] Types of oxidants in the technical solution: A combination of oxidants capable of oxidizing tellurium ions or mercury ions, specifically including Br2 (bromine), I2 (iodine), H2O2 (hydrogen peroxide), FeCl3 (ferric chloride) and combinations thereof.
[0069] The parameters related to the reaction mechanism in the technical solution include: the viscosity range of the protective etching solution (e.g., viscosity > 10 cP @ 25°C) and the control range of the etching rate (e.g., 5-50 nm / min).
[0070] Technical alternative A of this application: Dry etching Technical means: Reactive ion etching (RIE) or inductively coupled plasma (ICP) is used to bombard the thin film with gas plasmas such as CH4 / H2 / Ar.
[0071] Comparative analysis: Alternatives: It can achieve pixel isolation and is currently the mainstream competing technology in the industry.
[0072] The technical advantages of this application are as follows: Dry etching equipment is expensive, and plasma bombardment causes severe physical damage to the quantum dot surface (lattice destruction, ligand detachment), leading to increased dark current. The wet etching method of this invention is a "cold process," which is non-destructive, has a lower surface defect state density, and is extremely low in cost.
[0073] Alternative Option B: Use macromolecular polymer additives for thickening. Technical approach: The viscosity is artificially increased by adding high molecular weight polymers such as polyethylene glycol (PEG) and polyvinyl alcohol (PVA) to conventional low-viscosity solvents (such as methanol), instead of using ethylene glycol directly as a solvent.
[0074] Comparative analysis: Alternative: Theoretically feasible, it can also reduce the diffusion rate.
[0075] The technical advantages of this application are as follows: Polymer additives are extremely difficult to clean and easily remain inside porous films, leading to a decline in device performance. The ethylene glycol used in this invention acts as both a thickener and a solvent, making cleaning convenient and eliminating the risk of residue.
[0076] Strategy Recommendation: When drafting a patent, you can include "adding a thickener to adjust the viscosity" as a poor but covered implementation method to broaden the scope of protection.
[0077] Alternative C: Vapor phase chemical etching Technical means: The film is exposed to diluted bromine vapor or acidic gas to carry out the reaction.
[0078] Comparative analysis: Alternative: It avoids solvent contact and theoretically solves the solvent penetration problem.
[0079] Advantages of this application: Uniformity in vapor phase etching is extremely difficult to control (severe edge effects), and reaction products tend to accumulate in situ, hindering further reaction. The wet flow system of this invention can remove reaction products, ensuring uniform etching depth and surface cleanliness.
[0080] The implementation principle of the etching method for HgTe colloidal quantum dot films in this application embodiment is as follows: The core innovation of this method lies in using a high-viscosity solvent (such as ethylene glycol or propylene glycol) as the base solvent of the etching solution, combined with hydrobromic acid (HBr) and hydrogen peroxide (H2O2) as the main reaction components. By precisely controlling the concentration of the etching solution, the viscosity of the solvent and the reaction time, the HgTe colloidal quantum dot film can be gently etched. The specific implementation steps include four key stages: preparing the high-viscosity etching solution, performing solvent pre-wetting, diffusion-limited etching and reaction termination and cleaning. First, when preparing the high-viscosity etching solution, ethylene glycol or propylene glycol is selected as the base solvent, with solvent viscosities of 16 cP (ethylene glycol) and 13 cP (propylene glycol), respectively. The high-viscosity solvent reduces the diffusion rate of the reactants, so that the etching reaction can be carried out within a controllable range, avoiding the solvent from penetrating into the film too quickly, thereby preventing deep corrosion and overall peeling of the film layer. Secondly, the HgTe colloidal quantum dot film is pre-wetted with pure ethylene glycol or propylene glycol. The immersion time is usually controlled between 30 and 60 seconds. The high-viscosity solvent fills the nanopores of the film to form a liquid barrier layer, which restricts the diffusion of the etching solution and makes the etching reaction occur only on the surface of the film. Through the liquid barrier, the diffusion rate of the oxidant in the etching solution is effectively controlled, ensuring that the etching reaction only occurs in the outermost region of the film and avoiding the over-corrosion phenomenon that occurs in traditional wet etching. After pre-wetting, the film is quickly transferred to the etching solution for diffusion-limited etching. During this process, the high viscosity of the solvent further slows down the diffusion rate of bromide ions and oxidants, allowing the etching reaction to proceed stably for a longer period of time. Hydrobromic acid (HBr) breaks the Hg-Te bond in the etching solution, while hydrogen peroxide (H2O2) promotes the oxidation reaction of Te. The two work together to achieve mild and precise etching of HgTe colloidal quantum dot films. After the etching reaction is completed, the etching solution is quickly replaced with a solvent with low surface tension (such as isopropanol or acetonitrile) to terminate the etching reaction. The reaction products are removed by cleaning to prevent over-etching and film damage. Through precise control of the steps, the etching process avoids excessive solvent penetration and diffusion, reduces damage to the film surface, and improves the stability and patterning accuracy of the film layer. In the embodiments, the HgTe colloidal quantum dot films after etching were characterized by scanning optical microscopy (OM) and atomic force microscopy (AFM). It was found that the films treated by this method have clear and neat edges and highly vertical sidewalls. No "bulk etching" phenomenon or film peeling or flaking problems common in traditional wet etching were found. In contrast, when traditional low viscosity solvents (such as isopropanol) are used for etching, the etching reaction is too rapid and difficult to control, resulting in damage phenomena such as pores and discoloration in the film. Further comparative experiments showed that using a high-viscosity solvent system significantly improved etching accuracy, ensuring film surface quality and patterning effect. The advantage of this technology lies in optimizing the reaction rate and accuracy of the etching solution by precisely adjusting the concentration and volume ratio of hydrobromic acid and hydrogen peroxide, thus avoiding over-etching and surface damage. Using a high-viscosity solvent not only inhibits the diffusion rate of the solute, preventing excessively fast reactions and avoiding film damage, but also prevents secondary deposition of mercury ions through complexation reactions, ensuring the uniformity and stability of the film. Using a low surface tension solvent for cleaning effectively removes etching products, preventing residues from affecting device performance.
[0081] The above are all preferred embodiments of this application, and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.
Claims
1. A method for etching HgTe colloidal quantum dot thin films, characterized in that: This includes an etching method for HgTe colloidal quantum dot films, characterized in that the etching method comprises the following steps: Step 1: Prepare a high-viscosity etching solution, which contains ethylene glycol or propylene glycol as a base solvent and hydrobromic acid (HBr) and hydrogen peroxide (H2O2) as the main reaction components; Step 2: The HgTe colloidal quantum dot film is pre-wetted with solvent by initially immersing it in pure ethylene glycol or propylene glycol to form a liquid barrier; Step 3: Place the pre-wetted film into the etching solution for diffusion-limited etching to control the diffusion rate of bromide ions and oxidant in the etching solution; Step 4: Quickly replace the etching solution with a low surface tension solvent miscible with ethylene glycol (such as isopropanol or acetonitrile) to terminate the etching reaction and clean the film.
2. The etching method according to claim 1, characterized in that: The etching solution contains 40%-48% hydrobromic acid (HBr) and 30% hydrogen peroxide (H2O2). The volume ratio of the etching solution is: a mixture of hydrobromic acid and hydrogen peroxide is added to pure ethylene glycol or propylene glycol at a volume ratio of 1:50 to 1:200 to form the high-viscosity etching solution.
3. The etching method according to claim 2, characterized in that: The viscosity of the ethylene glycol or propylene glycol is 16 cP (ethylene glycol) or 13 cP (propylene glycol). Its high viscosity significantly reduces the diffusion rate of the reaction solute and controls the etching reaction rate.
4. The etching method according to claim 1, characterized in that: The solvent pre-wetting step involves immersing the HgTe colloidal quantum dot film in pure ethylene glycol, allowing the ethylene glycol to penetrate into the nanopores of the film and form a liquid barrier layer, so that the etching reaction occurs only on the outermost surface of the film.
5. The etching method according to claim 4, characterized in that: The pre-wetting step serves to control the diffusion rate of oxidant molecules in the etching solution by forming a liquid barrier on the film surface, thereby forcibly limiting the reaction to occur only in the outer region of the film.
6. The etching method according to claim 1, characterized in that: The diffusion-limited etching step is achieved by controlling the diffusion rate of bromide ions in the etching solution. The high-viscosity etching solution significantly slows down the diffusion of bromine molecules through the Stokes-Einstein equation, so that the etching reaction is carried out within a controlled range.
7. The etching method according to claim 6, characterized in that: During the etching process, ethylene glycol not only reduces the diffusion rate of bromide ions, but also binds to mercury ions through a complexation reaction, preventing mercury ions from redepositing on the surface of the quantum dot film.
8. The etching method according to claim 1, characterized in that: The hydrogen peroxide (H2O2) acts as an oxidant in the etching solution, promoting the oxidation reaction of Te (tellurium) atoms and generating tiny oxygen bubbles, which further promotes the renewal of the film reaction interface.
9. The etching method according to claim 1, characterized in that: The termination reaction and cleaning steps involve rapidly replacing the etching solution with a low surface tension solvent such as isopropanol or acetonitrile to stop the etching reaction and remove the reacted products, thus avoiding over-etching and damage to the film. The hydrobromic acid (HBr) and hydrogen peroxide (H2O2) in the etching solution work synergistically. Hydrobromic acid mainly breaks the Hg-Te bond, while hydrogen peroxide promotes the oxidation of Te. The combined effect of the two achieves a gentle yet precise etching of the HgTe colloidal quantum dot film. The etching method is particularly suitable for fabricating HgTe colloidal quantum dot thin film devices that require high-precision patterning, such as infrared detectors and infrared imaging devices.
10. The etching method according to claim 1, characterized in that: The method can effectively avoid the problems of internal film collapse and lateral drilling caused by excessively rapid solvent diffusion in traditional wet etching, thereby obtaining high-precision, low-damage HgTe colloidal quantum dot thin film patterning. The preparation of the etching solution and the reaction control conditions can be flexibly optimized by adjusting factors such as solvent type, hydrobromic acid concentration, hydrogen peroxide concentration and etching time to meet the etching requirements of HgTe colloidal quantum dot films with different thicknesses and porosities. The high-viscosity etching solution can effectively protect the surface ligands of quantum dots, prevent the loss of surface ligands or damage to quantum dots due to excessive etching, thereby improving the stability of the film and the performance of the device.