Methods for fabricating photomasks using deep silicon etching technology and methods for preparing halide perovskite array patterns using photomasks

Abstract

This invention discloses a method for fabricating a photomask using deep silicon etching technology, comprising the following steps: a) pretreatment of a silicon substrate; b) coating a pretreated silicon substrate with photoresist, followed by soft baking, resting, exposure, development, fixing, and post-baking to form the desired pattern on the silicon substrate; c) etching and cleaning the silicon substrate from step b to obtain the photomask. A method for fabricating perovskite array patterns using this photomask is also provided. This invention employs dry etching to fabricate perovskite array patterns, utilizing reactive ion beam etching (RIB) technology. The process is simple, the IIB equipment is simple in structure and inexpensive, and it is compatible with all MEMS-scale manufacturing plants, significantly reducing manufacturing costs. It proposes a new process strategy for perovskite array patterning, reducing side corrosion, improving patterning accuracy, and is suitable for micron-level pattern etching.

Description

Technical Field

[0001] This invention belongs to the field of perovskite array patterning technology, specifically relating to a method for fabricating a mask using deep silicon etching technology and a method for preparing halide perovskite array patterns using a mask. Background Technology

[0002] Halide perovskite (hereinafter referred to as "perovskite") materials possess advantages such as suitable band gaps, high carrier mobility, high absorption coefficients, low exciton binding energy, and long carrier lifetimes. Among them, perovskite-based quantum dots, nanowires, and other structural materials have become next-generation optoelectronic functional materials, achieving rapid development in fields such as light-emitting diodes, solar cells, and resistive switching memristors. Therefore, they have also attracted widespread attention in fields such as communications, displays, and photovoltaics. The efficient, precise, and large-scale fabrication of perovskite microstructure arrays on substrates is a crucial prerequisite for the device-based applications of perovskite materials.

[0003] Currently, in MEMS device manufacturing, array patterning is achieved using photolithography. This involves first using photolithography to perform hydrophilic-hydrophobic patterning on a special substrate, such as a flexible polyethylene terephthalate substrate or a silicon substrate with silica. This allows the perovskite precursor solution to be immersed only in the hydrophilic region. After degradation, the perovskite crystals form, resulting in a patterned perovskite image. However, in this photolithography process, the coating, development, and stripping steps require large amounts of solutions containing polar solvents. These polar solvents corrode the perovskite, making it impossible to fabricate perovskite thin-film arrays using photolithography.

[0004] All perovskite patterning methods developed in recent years have been based on the hydrophilic-hydrophobic template method. This involves patterning the perovskite substrate and then allowing the perovskite to deposit and grow within the hydrophilic region to obtain the final pattern. This method has several drawbacks, such as: 1. Limited perovskite types: Perovskites are diverse, and for specific functional devices such as LEDs, memristors, and photosensitive sensors, perovskites with specific photoelectric properties must be selected as the active material. However, some perovskite films are not suitable for the hydrophilic-hydrophobic template method. 2. Irregularity at pattern edges: When fabricating perovskite array patterns at resolutions of tens of nanometers to several micrometers, it is difficult to control the perovskite array dots within the pattern. This is because the hydrophilic-hydrophobic template method limits the pattern to which the perovskite precursor solution adheres, and then the perovskite continues to grow on the pattern. Typically, the perovskite grain size is tens to hundreds of micrometers, easily exceeding the pattern edge, leading to problems where the edges and size of the perovskite film pattern do not perfectly match the actual pattern. 3. High technical requirements: Certain requirements are placed on the substrate material. To achieve the photolithography process of the hydrophilic-hydrophobic layer, a special coating material (ITO, FTO, ZnO, TiO2) is generally needed on the substrate. 4. Complex process: The hydrophilic-hydrophobic template method requires coating a hydrophilic film and photoresist, and utilizing photolithography technology, resulting in a complex overall process with very high technical requirements, which is not conducive to the large-scale R&D and manufacturing of MEMS electronic devices. Summary of the Invention

[0005] The present invention aims to provide a method for fabricating a mask using deep silicon etching technology, and also to provide a method for preparing halide perovskite array patterns using a mask, which is another objective of the present invention.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A method for fabricating a photomask using deep silicon etching technology includes the following steps:

[0008] a. Pretreatment of silicon substrate;

[0009] b. Coat the silicon substrate with photoresist after the pretreatment in step a, soft bake, let stand, expose, develop, fix, and bake again to form the desired pattern on the silicon substrate.

[0010] c. Etch and clean the silicon substrate from step b to obtain a photomask.

[0011] In step c, the etching process adopts the Bosch etching process, which specifically includes a deposition-first etching-second etching cycle. The deposition conditions are as follows: the main RF gas is C4F8 with a flow rate of 100-600 sccm; the secondary RF gas is C4F8 with a flow rate of 50-200 sccm; the total gas pressure in the cavity is set to 10-60 mTorr; and the deposition time is 0.5-3 s.

[0012] First etching conditions: lower electrode power 50-90 W, main RF gas SF6, flow rate 100-600 sccm, total chamber pressure 10-60 mTorr, etching time 0.5-3 s;

[0013] Second etching conditions: lower electrode power 15-20 W, main RF gas SF6, flow rate 100-600 sccm, total chamber pressure 10-60 mTorr, etching time 0.5-3 s.

[0014] In step c, the deposition-first etching-second etching cycle is 300-800 times. The main RF incident power used in the Bosch etching process cycle is 1500-2400 W, and the secondary RF incident power is 200-800 W.

[0015] Step c, before etching, the silicon substrate is cleaned for 13-17 seconds using oxygen plasma with a main RF incident power of 2200-2700 W, an O2 flow rate of 180-220 sccm, a cavity gas pressure of 22-28 mTorr, and a lower electrode power of 70-90 W.

[0016] In step b, photoresist is coated onto the silicon substrate after the pretreatment in step a, and baked at a soft baking temperature of 90-110 ℃ for 8-12 min. After standing for 3-8 h, it is exposed and developed, and then baked at a post-baking temperature of 110-130 ℃ for 12-18 min to form the desired pattern on the silicon substrate.

[0017] In step b, the photoresist is a negative photoresist AZ4620, and the thickness of the photoresist on the silicon substrate is 7-9 μm. Exposure is performed using a laser direct-write lithography system; during development, the silicon substrate is immersed in S319 developer for 4-8 minutes, then removed and rinsed with deionized water.

[0018] In step a, the silicon substrate is pretreated by cleaning it with a cleaning solution under ultrasonic conditions and then drying it. The thickness of the silicon substrate is 50-100 µm. The silicon substrate is made of double-polished silicon wafers, and the cleaning solution is acetone, deionized water, isopropanol, or anhydrous ethanol.

[0019] Silicon substrate pretreatment method: Place the silicon substrate in acetone, deionized water and isopropanol in sequence, and ultrasonically clean each for 5 minutes. Remove the silicon substrate and dry it with a nitrogen gun.

[0020] The method for preparing halide perovskite array patterns using the mask plate obtained by the above method is characterized by comprising the following steps:

[0021] 1) Preparation of halide perovskite thin films;

[0022] 2) Dry etching array pattern: A mask is placed on the halide perovskite film in step 1). The pattern formed by the mask corresponds to the halide perovskite array pattern. After etching using reactive ion etching and inductively coupled plasma etching, the mask is removed to form the halide perovskite film array pattern.

[0023] In step 2), the mask includes a first mask and a second mask. The pattern formed by the combination of the first mask and the second mask corresponds to the halide perovskite array pattern. The reactive ion etching technology uses a reactive ion etching system, and the inductively coupled plasma etching technology uses an inductively coupled plasma etching system.

[0024] In step 2), the etching method includes the following steps:

[0025] a. First, cover the halide perovskite film with the first mask plate, fix it in position, place it in the reaction chamber of the reactive ion etching system, perform etching under vacuum conditions, and then take out the halide perovskite film and the first mask plate.

[0026] b. Place the halide perovskite thin film and the first mask in the rapid sample introduction chamber of the inductively coupled plasma etching system under vacuum conditions (vacuum degree is 1.0e during transport). -2 The halide perovskite thin film and the first mask are transferred to the etching chamber at a vacuum level of 1.0 e Pa. -7 -1.0 e -9 Pa is used for etching. After etching is completed, the halide perovskite film and the first mask are transferred back to the rapid sample injection chamber, removed, and the first mask is unloaded.

[0027] c. Next, cover the halide perovskite film with a second mask. After positioning and fixing, place it in the reaction chamber of the reactive ion etching system and the etching chamber of the inductively coupled plasma etching system in sequence for etching. After etching is completed, the halide perovskite film and the second mask are transferred back to the rapid sample injection chamber, taken out, and the second mask is removed.

[0028] In step 2), the etching conditions for step a are: evacuate the reaction chamber to 10... -5Pa, the etching gas is a combination atmosphere of CF4 and CHF3, the flow rate of CF4 is 20-40 sccm, the flow rate of CHF3 is 5-20 sccm, the gas pressure is 1-8 Pa, the plasma excitation radio frequency power is 50-100 W, and the etching time is 5-10 min.

[0029] Step b etching conditions: upper electrode power 200-800 W, lower electrode power 20-80 W, etching gas is a combination atmosphere of chlorine and argon, gas pressure 2-6 mTorr, chlorine flow rate 10-15 sccm, argon flow rate 7-10 sccm, etching time 1-2 min.

[0030] Perovskite thin film materials are diverse, each possessing different photoelectric properties. The dry etching method of this invention does not limit the type, elements, morphology, or structure of the perovskite thin film. It is applicable to both traditional perovskite thin films and perovskite thin films with modified elements (A / B / X). The morphology of the perovskite thin film can be a crystalline grain capping layer, linear, or network structure.

[0031] Perovskite thin film materials can be of the ABX3 type, where A can be NH4. + [(CH3)NH4] + [(CH2)3NH2] + [NH2(CH)NH2] + [(CH3)2NH2] + [(C2H5)NH3] + [C(NH2)3] + [(CH3)4N] + Single or multiple organic groups, or Cs + 、Rb + K + One or more metal ions; B is Pb 2+ Sn 2+ One or more of the same heavy metal ions; X is a halide ion, Cl - ,Br - I - One or more of them.

[0032] A method for preparing perovskite thin films includes the following steps:

[0033] 1. Substrate / base cleaning;

[0034] 2. Perovskite thin film deposition: One-step spin coating or two-step spin coating method is used.

[0035] In step 1, the cleaning method is as follows: First, use a cleaning agent prepared with deionized water (deionized water and scouring powder are conventionally prepared, and the ratio is not particularly important) to clean (ultrasonic cleaning method can be used) once or twice, rinse thoroughly with deionized water and blow dry; then clean with acetone (ultrasonic cleaning method can be used), and blow dry; then clean with alcohol (ultrasonic cleaning method can be used), and blow dry; O2 or Ar plasma can be used to remove organic impurities on the substrate / substrate surface; the substrate material can be Si-based wafer, sapphire (Al2O3), ITO, glass, polyethylene, polyethylene terephthalate (PET) or polyimide (PI) and other materials.

[0036] The one-step spin-coating method involves nucleation and growth of perovskite thin films in a precursor solution containing all perovskite compounds. The specific method is as follows:

[0037] 1) Preparation of perovskite precursor solution: Mix ABX3 compound with solvent to prepare precursor solution;

[0038] 2) Spin-coating and spin coating: The cleaned substrate or sheet is adsorbed onto the spin coater or spin coater, and the perovskite precursor solution is covered on the surface of the substrate or sheet. The spin coater is pre-run at 300-500 rpm for 3-10 seconds, and then run at 2000-3000 rpm for 30-60 seconds.

[0039] 3) Place the substrate or sheet with spin-coated perovskite precursor solution on a heating plate at 100-180º for annealing to allow the solvent to evaporate and crystallize to form a perovskite thin film.

[0040] To prepare CH3NH3PbI3 thin films, 1) prepare perovskite precursor solution: mix a certain amount of CH3NH3I and PbI2 in an organic solvent at a molar ratio of 1:1, and the total molar concentration of CH3NH3I and PbI2 is 1-100 mol / mL.

[0041] 2) Spin coating process can be used: The substrate or sheet is adsorbed on the spin coater or spin coater, and the perovskite precursor solution is covered on the surface of the substrate or sheet. It is pre-run at a speed of 300-500 rpm for 3-10 s, and then run at a speed of 2000-3000 rpm for 30-60 s.

[0042] 3) Place the substrate or sheet with the spin-coated perovskite precursor solution on a hot plate at 100-180º for annealing to evaporate the solvent and crystallize to form a perovskite film. The organic solvent is one or a mixture of two or more of N,N-dimethylformamide (DMF), γ-butyrolactone (GBL), and dimethyl sulfoxide (DMSO).

[0043] The difference between this method and the method for preparing CH3NH3PbI3 thin films is that, in the preparation of [(CH2)3NH2]PbI3 thin films, the perovskite precursor solution is prepared by mixing a certain concentration of [(CH2)3NH2]I and PbI2 according to a certain ratio and molar mass. The molar ratio of [(CH2)3NH2]I to PbI2 is 1:1, and the total molar concentration of [(CH2)3NH2]I and PbI2 is 1-100 mol / L.

[0044] To prepare [CH3NH3]PbBr3 thin films, a mixed salt solution of [CH3NH3]Br and PbBr2 of a certain concentration was prepared according to the ratio and molar mass, with the molar ratio of [CH3NH3]Br to PbBr2 being 1:1 and the total molar concentration being 1-100 mol / L.

[0045] To prepare [CH3NH3]SnI3 thin films, a mixed salt solution of [(CH2)3NH2]I and SnI2 of a certain concentration was prepared according to the ratio and molar mass. The molar ratio of [(CH2)3NH2]I to SnI2 was 1:1, and the total molar concentration was 1-100 mol / L.

[0046] Other similar [(CH2)3NH2]PbBr 3-a-b I a Cl b Perovskites with mixed elemental compositions at the A, B, or X sites can be prepared by analogy to the above method, and the corresponding salt mixed solutions can be prepared by using one or more of the following solvents: DMF, GBL, and DMSO.

[0047] The two-step spin coating method is suitable for perovskite thin film materials consisting of two or more compounds. Specifically, the two or more compounds are mixed separately to form precursor solvents. Each precursor solvent is then deposited step by step, followed by heating and annealing to evaporate the solvent and crystallize to form a perovskite thin film.

[0048] The two-step method for preparing CH3NH3PbI3 thin films is as follows: 1) Prepare perovskite precursor solutions separately. Dissolve a certain amount of CH3NH3I salt in isopropanol (IPA) to prepare a solution with a concentration of 1-100 mol / mL. Dissolve PbI2 in DMF solvent to prepare a solution with a concentration of 1-100 mol / mL.

[0049] 2) Stepwise deposition: A PbI2 film can be deposited on the substrate or substrate using a spin-coating process. The substrate or substrate is pre-run at 300-500 rpm for 3-10 s, then run at 2000-3000 rpm for 30-60 s. Then, CH3NH3I salt is deposited by immersion or spin-coating. The immersion method involves placing the substrate or substrate into the salt solution for a few seconds. The spin-coating method is the same as described above.

[0050] 3) Place the substrate or sheet on a heating plate at 100-180º for annealing to allow the solvent to evaporate and crystallize to form a perovskite thin film.

[0051] To prepare [(CH2)3NH2]PbI3 thin films, perovskite precursor solutions were prepared into [(CH2)3NH2]I and PbI2 salt solutions at specific concentrations and ratios. To prepare [CH3NH3]PbBr3 thin films, perovskite precursor solutions were prepared into [CH3NH3]Br and PbBr2 salt solutions at specific concentrations and ratios. To prepare [CH3NH3]SnI3 thin films, the precursor solutions were prepared into [(CH2)3NH2]I and SnI2 salt solutions at specific concentrations and ratios. Other methods were similar to those for [(CH2)3NH2]PbBr... 3-a-b I a Cl b Perovskites with mixed elemental compositions at the A, B, or X sites can be prepared by analogy to the above method, using two corresponding salt solutions. The solvent used to prepare the precursor solution can be one or more of IPA, DMF, GBL, and DMSO. Steps 2) and 3) refer to the two-step method described above for preparing CH3NH3PbI3 thin films.

[0052] Compared with the prior art, the present invention has the following beneficial effects:

[0053] 1) This invention utilizes deep silicon etching (Bosch) process to fabricate silicon-based cutout boards as dry etching mask tools for patterning perovskite arrays (ten micrometers and above);

[0054] 2) Dry etching is used to prepare perovskite array patterns. The perovskite is etched using a combination of reactive ion beam and inductive coupling. The process is simple, the reactive ion beam etching equipment is simple in structure and inexpensive, and it is compatible with all MEMS large-scale manufacturing plants, which greatly reduces manufacturing costs. It provides a new process strategy for perovskite array patterning, reduces side corrosion, improves patterning accuracy, and is suitable for micron-level pattern etching. 3) It avoids the situation of perovskite being corroded by solvents and is not limited by the type of perovskite. It is suitable for all types of perovskite thin film materials, such as glass or PET plastic substrates with ITO, FTO, ZnO, TiO2 substrates, which broadens the compatibility for manufacturing various functional materials. Attached Figure Description

[0055] Figure 1 Here is a SEM image of the cross-section of the halide perovskite thin film in Example 1;

[0056] Figure 2 Here is a cross-sectional SEM image of a halide perovskite array from Example 1;

[0057] Figure 3 This is an optical photograph of the perovskite pattern with a linewidth of 100 micrometers etched from the halide perovskite in Example 1.

[0058] Figure 4 This is an optical photograph of a perovskite pattern with a linewidth of 100 micrometers etched using reactive ion beam etching, as shown in Example 4, which is a comparative example.

[0059] Figure 5 This is a schematic diagram of the structure of the first mask plate in Example 1;

[0060] Figure 6 This is a schematic diagram of the structure of the second mask plate in Example 1. Detailed Implementation

[0061] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention are described in detail below. However, the following embodiments are only some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other implementation methods obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0062] Example 1

[0063] A method for fabricating a mask using deep silicon etching technology was employed to etch a 500 nm thick (Cs) layer. x (CH3NH2) y (CH3NH3) 1-x-y )Pb(I 1-z Br z 3. Thin film array patterning, including the following steps:

[0064] a. Pretreatment of silicon substrate: The thickness of the silicon substrate is 100 µm. The silicon substrate is made of double-polished silicon wafer. The silicon substrate is placed in acetone, deionized water and isopropanol in sequence, and ultrasonically cleaned for 5 min each. The silicon substrate is then removed and dried with a nitrogen gun.

[0065] b. Coat the silicon substrate with photoresist after the pretreatment in step a, soft bake, let stand, expose, develop, fix, and bake again to form the desired pattern on the silicon substrate.

[0066] In step b, photoresist (negative photoresist AZ4620) is coated on the silicon substrate after the pretreatment in step a. The thickness of the photoresist coating is 9 μm. After baking at a soft baking temperature of 100 ℃ for 10 min and standing for 6 h, exposure, development and fixing are performed using a laser direct writing lithography system. The silicon substrate is immersed in S319 developer for 6 min, taken out, rinsed with deionized water, and then placed on a 120 ℃ heating plate for post-baking for 15 min.

[0067] c. Attach the silicon substrate from step b to the sample tray using high-temperature thermally conductive silicone oil. Place the tray into the automated sample loading chamber of the deep silicon etching system (SPTS Omega LPX rapier). Set the sample stage temperature in the reaction chamber to 10 °C, the back helium pressure to 15 Torr, the main RF incident power to 2400 W, the O2 flow rate to 200 sccm, the chamber pressure to 25 mTorr, and the lower electrode power to 78 W. Clean the silicon substrate with oxygen plasma for 15 s.

[0068] The silicon substrate in step b is then etched using the Bosch etching process, which includes a deposition-first etching-second etching cycle with 326 cycles. The main radio frequency incident power used in each Bosch etching cycle is 2200 W and the secondary radio frequency incident power is 500 W.

[0069] Deposition conditions: The lower electrode power was set to 0 W, the main radio frequency gas was C4F8 with a flow rate of 360 sccm; the secondary radio frequency gas was C4F8 with a flow rate of 120 sccm; the total gas pressure in the chamber was set to 35 mTorr; and the deposition time was 1.4 s.

[0070] First etching conditions: lower electrode power 80 W, main RF gas SF6, flow rate 300 sccm, total chamber pressure 25 mTorr, etching time 1.3 s;

[0071] The second etching conditions were as follows: the lower electrode power was 17 W, the main radio frequency gas was SF6 with a flow rate of 400 sccm, the total gas pressure in the cavity was set to 35 mTorr, and the etching time was 1.5 s.

[0072] After the Bosch process is completed, the silicon substrate is removed and immersed in isopropyl alcohol (IPA) to clean the silicone oil on the bottom of the silicon substrate. It is then dried with an N2 gun and immersed in acetone to clean the residual photoresist on the surface of the silicon substrate. Finally, it is dried with an N2 gun to obtain the photomask.

[0073] Taking a perovskite array with n=20 (columns) × m=20 (rows) as an example, the lattice is a square with side length a = b = 100 μm, and the row and column resolutions are c = d = 100 μm.

[0074] The photomask is divided into a first photomask and a second photomask. The pattern formed by the combination of the first photomask and the second photomask corresponds to the halide perovskite array pattern.

[0075] 1. The structure formed by the first mask is a perforated grid-like horizontal striped mask, such as... Figure 5As shown, the length and width of the horizontal stripes are n*d and b, respectively, and the longitudinal spacing between the horizontal stripes and the adjacent stripes is c, with a total of m stripes, which can ensure that the dimensional accuracy of the grid stripes is better than 1 μm.

[0076] 2. The structure formed by the second mask is a perforated grid-like vertical striped mask, such as... Figure 6 As shown, the length and width of the vertical stripes are m*c and a, respectively, and the lateral spacing between adjacent vertical stripes is d, for a total of n stripes. This ensures that the stripe size accuracy is better than 1 μm.

[0077] The method for preparing halide perovskite array patterns using the mask plate obtained by the above method is characterized by comprising the following steps:

[0078] 1) Preparation of halide perovskite thin films (selecting 500 nm thick (Cs) x (CH3NH2) y (CH3NH3) 1-x-y )Pb(I 1- z Br z 3. Thin film, one-step method): a. Substrate cleaning: First, use a cleaning agent prepared with deionized water (prepared by mixing deionized water and scouring powder in a mass ratio of 15:1) to ultrasonically clean twice, rinse with deionized water and blow dry; then use acetone to ultrasonically clean once and blow dry; then use alcohol to ultrasonically clean once and blow dry; O2 plasma can remove organic impurities on the surface of Si-based wafer substrate.

[0079] b. Perovskite thin film deposition: (1) Preparation of perovskite precursor solution: A certain amount of CH3NH2I, CH3NH3Br, PbI2 and PbBr2 are mixed in a mixture of DMF and DMSO (DMF and DMSO in equal volume). CsI is dissolved in DMF solution. Each substance is prepared with a molar concentration of 1 mol / L. The above 5 solvent substances are then mixed in equal molar ratio.

[0080] (2) Spin coating: The substrate is adsorbed on the spin coater, and the perovskite precursor solution is covered on the substrate surface. The substrate is pre-run at 300 rpm for 5 s, and then run at 2000 rpm for 30 s.

[0081] (3) The substrate with the spin-coated perovskite precursor solution was placed on a 100º hot plate for annealing to evaporate the solvent and crystallize to form a perovskite film. SEM images of the film cross-section are shown below. Figure 1 As shown.

[0082] 2) Dry etching array pattern: a) First, on the halide perovskite thin film (Cs x (CH3NH2) y (CH3NH3)1-x-y )Pb(I 1-z Br z 3) Cover the first mask and fix it in place (using an optical microscope and a substrate transfer platform to calibrate the relative positions of the mask and the perovskite film, completing the alignment and correction operation of the mask and substrate (film and substrate), and using a spring clamping device to fix the mask and the perovskite film), then place it in the reaction chamber of the reactive ion etching system (RIE), close the reaction chamber, and evacuate to 10 -5 Pa, the etching gas is a combination atmosphere of CF4 and CHF3, the flow rate of CF4 is 30 sccm, the flow rate of CHF3 is 10 sccm, the gas pressure is 2 Pa, the plasma excitation radio frequency power is 80 W, the etching time is 6 min; the halide perovskite film and the first mask are removed.

[0083] The reaction formula is as follows:

[0084] CH3NH2 + + e - → CH3NH2(g) preferentially reacts

[0085] CH3NH2+ e - → CHx (g) + NHx (g) preferential reaction

[0086] CH3NH3+ e - → CHx (g) + NHx (g) + H + Priority response

[0087] Pb 2+ + F - → PbF2(g)

[0088] Pb 2+ + F - → PbF2(s) partially solidified on the substrate

[0089] Cs + + F - → CsF (g)

[0090] Cs + + F - → CsF (s) partially solidified on the substrate

[0091] I - + H + → HI (g)

[0092] b. Place the halide perovskite thin film and the first mask in the rapid sample introduction chamber of the inductively coupled plasma etching system (ICP) under vacuum conditions (vacuum level 1.0e during transport).-2 The halide perovskite thin film and the first mask are transferred to the etching chamber at a vacuum level of 1.0 e Pa. -7 Pa, etching was performed, and the first mask was removed; etching conditions: the sample stage temperature was set to 30℃, the back He gas pressure was set to 10 Torr, the upper electrode power was 800 W, the lower electrode power was 50 W, the etching gas was a combination atmosphere of chlorine and argon, the gas pressure was 4 mTorr, the chlorine flow rate was 12 sccm, the argon flow rate was 9 sccm, and the etching time was 2 min;

[0093] The reaction formula is as follows:

[0094] Pb 2+ + Cl - → PbCl2(g) reacts very readily

[0095] Pb 2+ + F - → PbF2(g) Next

[0096] Cs + + Cl - → CsCl (g) reacts readily

[0097] Cs + + F - → CsF (g)

[0098] I - + H + → HI (g)

[0099] CH3NH2 + + e - → CH3NH2(g)

[0100] CH3NH3+ e - → CH x (g) + NH x (g)+ H +

[0101] c. Next, cover the halide perovskite film with a second mask, fix it in position, and then place it in the reaction chamber of the reactive ion etching system and the etching chamber of the inductively coupled plasma etching system in sequence. Etch according to steps a and b (the process parameters in this step are the same as in steps a and b). After etching is completed, the halide perovskite film and the second mask are transferred back to the rapid sample injection chamber, taken out, and the second mask is removed.

[0102] The obtained SEM images of the perovskite array point cross sections, such as Figure 2 As shown. Perovskite, such as Figure 3 As shown.

[0103] Depend on Figure 2 As can be seen, the thin film is grown on silicon dioxide with Si as the substrate. An array point was randomly selected, and SEM images were taken at three locations within that point. The SEM images within the green and blue frames represent the edges of the array point, respectively. It can be seen that the perovskite film edge structure is clear, and the area outside the array point is cleanly etched without residue. The array point thickness is approximately 500 nm. From the SEM image within the yellow frame in the middle, the total cross-sectional thickness of the film is approximately 500 nm, indicating that after etching, the thickness of the array point is uniform from the edge to the center, without over-etching thinning of the film at the array point, and no lateral etching occurred at the edges. Figure 3 It can be seen that no lateral etching occurred on the side of the perovskite film pattern.

[0104] Example 2

[0105] A method for fabricating a photomask using deep silicon etching technology includes the following steps:

[0106] a. Pretreatment of silicon substrate: The thickness of the silicon substrate is 100 µm. The silicon substrate is made of double-polished silicon wafer. The silicon substrate is placed in acetone, deionized water and isopropanol in sequence and ultrasonically cleaned for 5 min each. The silicon substrate is then removed and dried with a nitrogen gun.

[0107] b. Coat the silicon substrate with photoresist after the pretreatment in step a, soft bake, let stand, expose, develop, fix, and bake again to form the desired pattern on the silicon substrate.

[0108] In step b, photoresist (negative photoresist AZ4620) is coated on the silicon substrate after the pretreatment in step a. The thickness of the photoresist coating is 7 μm. After baking at a soft baking temperature of 100 ℃ for 10 min and standing for 6 h, exposure, development and fixing are performed using a laser direct writing lithography system. The silicon substrate is immersed in S319 developer for 8 min, taken out, rinsed with deionized water, and then baked at a post-baking temperature of 130 ℃ for 12 min.

[0109] c. Attach the silicon substrate from step b to the sample tray using high-temperature thermally conductive silicone oil. Place the tray into the automated sample loading chamber of the deep silicon etching system (SPTS Omega LPX rapier). Set the sample stage temperature in the reaction chamber to 10 °C, the back helium pressure to 15 Torr, the main radio frequency incident power to 2400 W, the O2 flow rate to 200 sccm, the chamber pressure to 25 mTorr, and the lower electrode power to 78 W. Clean the silicon substrate with oxygen plasma for 15 s.

[0110] The silicon substrate in step b is then etched using the Bosch etching process, which includes a deposition-first etching-second etching cycle with 300 cycles. The main radio frequency incident power used in each Bosch etching cycle is 1500 W and the secondary radio frequency incident power is 800 W.

[0111] Deposition conditions: The lower electrode power was set to 0 W, the main radio frequency gas was C4F8 with a flow rate of 550 sccm; the secondary radio frequency gas was C4F8 with a flow rate of 200 sccm; the total gas pressure in the cavity was set to 50 mTorr; and the deposition time was 3 s.

[0112] First etching conditions: lower electrode power 90 W, main RF gas SF6, flow rate 100 sccm, total chamber pressure 20 mTorr, etching time 1 s;

[0113] Second etching conditions: lower electrode power 15 W, main RF gas SF6, flow rate 500 sccm, total cavity pressure 20 mTorr, etching time 3 s;

[0114] After the Bosch process, the silicon substrate is removed and immersed in isopropanol (IPA) to clean the silicone oil on the bottom of the substrate. It is then dried with an N2 gun and further immersed in acetone to clean any remaining photoresist on the substrate surface. Finally, it is dried with an N2 gun to obtain the photomask. The photomask includes a first photomask and a second photomask. The pattern formed by the combination of the first and second photomasks corresponds to the halide perovskite array pattern. The photomask structure is the same as in Example 1.

[0115] The method for preparing halide perovskite array patterns using the mask obtained by the above method includes the following steps:

[0116] 1) Preparation of halide perovskite thin films (selecting [CH3NH3]PbBr3 thin films, one-step method): a. Substrate cleaning: First, use a cleaning agent prepared with deionized water (deionized water and scouring powder are prepared in a mass ratio of 20:1) to ultrasonically clean twice, rinse with deionized water and blow dry; then use acetone to ultrasonically clean once and blow dry; then use alcohol to ultrasonically clean once and blow dry; O2 plasma can remove organic impurities on the surface of Si-based wafer substrate.

[0117] b. Perovskite film deposition: (1) Preparation of perovskite precursor solution: A certain amount of [CH3NH3]Br and PbBr2 are mixed in DMF at a molar ratio of 1:1, with a total molar concentration of 2 mol / L;

[0118] (2) Spin coating: The substrate is adsorbed on the spin coater, and the perovskite precursor solution is covered on the surface of the substrate. The substrate is pre-run at 400 rpm for 3 s, and then run at 3000 rpm for 40 s.

[0119] (3) Place the substrate or sheet with spin-coated perovskite precursor solution on a 150º heating plate for annealing to allow the solvent to evaporate and crystallize to form a perovskite thin film.

[0120] 2) Dry etching array pattern:

[0121] a. First, cover the halide perovskite thin film ([CH3NH3]PbBr3 thin film) with a first mask, and fix it in place (using an optical microscope and a substrate transfer platform to calibrate the relative positions of the mask and the perovskite thin film, completing the alignment and correction operation of the mask and substrate (thin film and substrate), and using a spring clamping device to fix the mask and the perovskite thin film). Then, place it in the reaction chamber of the reactive ion etching system (RIE), close the reaction chamber, and evacuate to 10. -5 Pa, the etching gas is a combination atmosphere of CF4 and CHF3, the flow rate of CF4 is 35 sccm, the flow rate of CHF3 is 7 sccm, the gas pressure is 3 Pa, the plasma excitation radio frequency power is 100 W, the etching time is 10 min; the halide perovskite film and the first mask are taken out.

[0122] The reaction formula is as follows:

[0123] CH3NH2 + + e - → CH3NH2(g) preferentially reacts

[0124] CH3NH2+ e - → CHx (g) + NHx (g) preferential reaction

[0125] CH3NH3+ e - → CHx (g) + NHx (g) + H + Priority response

[0126] Pb 2+ + F - → PbF2(g)

[0127] Pb 2+ + F - → PbF2(s) partially solidified on the substrate

[0128] b. Place the halide perovskite thin film and the first mask in the rapid sample introduction chamber of the inductively coupled plasma etching system (ICP) under vacuum conditions (vacuum level 1.0e during transport). -2 The halide perovskite thin film and the first mask are transferred to the etching chamber at a vacuum level of 1.0 e Pa. -9Pa, etching was performed, and the first mask was removed; etching conditions: the sample stage temperature was set to 30℃, the back He gas pressure was set to 10 Torr, the upper electrode power was 600 W, the lower electrode power was 45 W, the etching gas was a combination atmosphere of chlorine and argon, the gas pressure was 6 mTorr, the chlorine flow rate was 15 sccm, the argon flow rate was 10 sccm, and the etching time was 2 min;

[0129] The reaction formula is as follows:

[0130] Pb 2+ + Cl - → PbCl2(g) reacts very readily

[0131] Pb 2+ + F - → PbF2(g) Next

[0132] Cs + + Cl - → CsCl (g) reacts readily

[0133] Cs + + F - → CsF (g)

[0134] I - + H + → HI (g)

[0135] CH3NH2 + + e - → CH3NH2(g)

[0136] CH3NH3+ e - → CH x (g) + NH x (g)+ H +

[0137] c. Next, cover the halide perovskite film with a second mask. After positioning and fixing, place it in the reaction chamber of the reactive ion etching system and the etching chamber of the inductively coupled plasma etching system, respectively. Etch according to steps a and b (the process parameters in this step are the same as in steps a and b). After etching, transfer the halide perovskite film and the second mask back to the rapid sample inlet chamber, remove them, and detach the second mask. The perovskite pattern is as follows: Figure 3 As shown.

[0138] Depend on Figure 3 It can be seen that the thin film pattern of the present invention is etched according to the mask pattern, and no side etching occurs on the side of the thin film pattern.

[0139] Example 3

[0140] A method for fabricating a photomask using deep silicon etching technology includes the following steps:

[0141] a. Pretreatment of silicon substrate: The thickness of the silicon substrate is 50 µm. The silicon substrate is made of double-polished silicon wafer. The silicon substrate is placed in acetone, deionized water and isopropanol in sequence and ultrasonically cleaned for 5 min each. The silicon substrate is then removed and dried with a nitrogen gun.

[0142] b. Coat the silicon substrate with photoresist after the pretreatment in step a, soft bake, let stand, expose, develop, fix, and bake again to form the desired pattern on the silicon substrate.

[0143] In step b, photoresist (negative photoresist AZ4620) is coated on the silicon substrate after the pretreatment in step a. The thickness of the photoresist coating is 9 μm. After baking at a soft baking temperature of 100 ℃ for 10 min and standing for 6 h, exposure, development and fixing are performed using a laser direct writing lithography system. The silicon substrate is immersed in S319 developer for 4 min, taken out, rinsed with deionized water, and then baked at a post-baking temperature of 110 ℃ for 18 min.

[0144] c. Attach the silicon substrate from step b to the sample tray using high-temperature thermally conductive silicone oil. Place the tray into the automated sample loading chamber of the deep silicon etching system (SPTS Omega LPX rapier). Set the sample stage temperature in the reaction chamber to 10 °C, the helium pressure to 15 Torr, the main radio frequency incident power to 2500 W, the O2 flow rate to 200 sccm, the chamber pressure to 25 mTorr, and the lower electrode power to 78 W. Clean the silicon substrate with oxygen plasma for 15 s.

[0145] The silicon substrate in step b is then etched using the Bosch etching process, which includes a deposition-first etching-second etching cycle with 450 cycles. The main radio frequency incident power used in each Bosch etching cycle is 2400 W and the secondary radio frequency incident power is 800 W.

[0146] Deposition conditions: The lower electrode power was set to 0 W, the main radio frequency gas was C4F8 with a flow rate of 550 sccm; the secondary radio frequency gas was C4F8 with a flow rate of 100 sccm; the total gas pressure in the chamber was set to 55 mTorr; and the deposition time was 1.5 s.

[0147] First etching conditions: lower electrode power 90 W, main RF gas SF6, flow rate 330 sccm, total cavity pressure 60 mTorr, etching time 2 s;

[0148] Second etching conditions: lower electrode power 20 W, main RF gas SF6, flow rate 440 sccm, total chamber pressure 40 mTorr, etching time 3 s;

[0149] After the Bosch process is completed, the silicon substrate is removed and immersed in isopropyl alcohol (IPA) to clean the silicone oil on the bottom of the silicon substrate. It is then dried with an N2 gun and immersed in acetone to clean the residual photoresist on the surface of the silicon substrate. Finally, it is dried with an N2 gun to obtain the photomask. The structure of the photomask is the same as in Example 1.

[0150] The method for preparing halide perovskite array patterns using the mask plate obtained by the above method is characterized by comprising the following steps:

[0151] Preparation of halide perovskite thin films ([C2H5NH3]PbI3, one-step method): a. Substrate cleaning: First, use a cleaning agent prepared with deionized water (deionized water and scouring powder are prepared in a mass ratio of 25:1) for ultrasonic cleaning twice, rinse with deionized water and blow dry; then use acetone for ultrasonic cleaning once and blow dry; then use alcohol for ultrasonic cleaning once and blow dry; Ar plasma is used to remove organic impurities on the surface of the Si-based wafer substrate.

[0152] b. Perovskite thin film deposition: (1) Preparation of perovskite precursor solution: A certain amount of C2H5NH3I and PbI2 are mixed in DMF solvent, and each substance is prepared with a molar concentration of 5 mol / L. Then the above two solvent substances are mixed in equal proportion.

[0153] (2) Spin coating: The substrate is adsorbed on the spin coater, and the perovskite precursor solution is covered on the substrate surface. The substrate is pre-run at 300 rpm for 5 s, and then run at 5000 rpm for 30 s.

[0154] (3) The substrate with spin-coated perovskite precursor solution is placed on a 100º heating plate for annealing to allow the solvent to evaporate and crystallize to form a perovskite film.

[0155] 2) Dry etching array pattern: a) First, cover the halide perovskite thin film ([C2H5NH3]PbI3 thin film) with a first mask, and fix it in place (using an optical microscope and a substrate transfer platform to calibrate the relative positions of the mask and the perovskite thin film, complete the alignment and correction operation of the mask and substrate (thin film and substrate), and use a spring clamping device to fix the mask and the perovskite thin film). Then, place it in the reaction chamber of the reactive ion etching system (RIE), close the reaction chamber, and evacuate to 10. -5Pa, the etching gas is a combination atmosphere of CF4 and CHF3, the flow rate of CF4 is 40 sccm, the flow rate of CHF3 is 5 sccm, the gas pressure is 8 Pa, the plasma excitation radio frequency power is 100 W, the etching time is 5 min; the halide perovskite film and the first mask are removed.

[0156] The reaction formula is as follows:

[0157] C2H5NH3 + + e - → C2H5NH3(g) preferentially reacts

[0158] C2H5NH3 + + e - → CH x (g) + NH x (g) Preferred reaction

[0159] C2H5NH3+ e - → CH x (g) + NH x (g)+ H + Priority response

[0160] Pb 2+ + F - → PbF2(g)

[0161] Pb 2+ + F - → PbF2(s) partially solidified on the substrate

[0162] I - + H + → HI (g)

[0163] b. Place the halide perovskite thin film and the first mask in the rapid sample introduction chamber of the inductively coupled plasma etching system (ICP) under vacuum conditions (vacuum level 1.0e during transport). -2 The halide perovskite thin film and the first mask are transferred to the etching chamber at a vacuum level of 1.0 e Pa. -9 Pa, etching was performed, and the first mask was removed; etching conditions: the sample stage temperature was set to 30℃, the back He gas pressure was set to 10 Torr, the upper electrode power was 600 W, the lower electrode power was 45 W, the etching gas was a combination atmosphere of chlorine and argon, the gas pressure was 6 mTorr, the chlorine flow rate was 15 sccm, the argon flow rate was 10 sccm, and the etching time was 2 min;

[0164] The reaction formula is as follows:

[0165] Pb2+ + Cl - → PbCl2(g) reacts very readily

[0166] Pb 2+ + F - → PbF2(g) Next

[0167] I - + H + → HI (g)

[0168] C2H5NH2 + + e - → CH3NH2(g)

[0169] C2H5NH3+ e - → CH x (g) + NH x (g)+ H +

[0170] c. Next, cover the halide perovskite film with a second mask. After positioning and fixing, place it in the reaction chamber of the reactive ion etching system and the etching chamber of the inductively coupled plasma etching system, respectively. Etch according to steps a and b (the process parameters in this step are the same as in steps a and b). After etching is completed, transfer the halide perovskite film and the second mask back to the rapid sample injection chamber, take them out, and remove the second mask.

[0171] This was the first time RIE was used to excite a combination of CF4 and CHF3 gases using plasma, with F being the main active ion. - Because perovskite thin films are composed of C, H, N, and Pb, the main components at the A-site include C, H, and N. Among these, Pb readily reacts with F. - Ions combine to form PbF2, but due to its large molecular weight, a certain amount of it will be deposited as a solid phase on the substrate, and it is difficult to re-excite it into a gaseous phase and remove it from the substrate. Therefore, when using RIE to etch a thick perovskite film for the first time, reaction byproducts will be deposited on the substrate surface in the etched area.

[0172] To improve process quality, ICP can be reused to etch away byproducts deposited on the substrate. The ICP process uses a combination of Cl2 and Ar atmospheres. Because the lower electrode under the sample tray in the reaction chamber plays a role, it creates ion traction perpendicular to the sample direction inside the reaction chamber. This ion traction, achieved by bombarding the solid PbCl2 deposited on the substrate surface with electrons or Ar ions, forms free Pb. 2+ Ions, along with Cl- excited in the reaction chamber - The reaction produces gaseous PbCl2, while simultaneously expelling the reaction chamber.

[0173] Example 4 Comparative Experiment

[0174] Comparative Example: The difference from Example 1 is that in step 2) of the method for preparing halide perovskite array patterns using the mask plate prepared by the above method, dry etching of the array pattern is performed: only reactive ion etching is used, and the etching time is 8 min. The resulting perovskite pattern is as follows. Figure 4 As shown.

[0175] Depend on Figure 4 As can be seen in the comparative example, when reactive ion beam etching was used alone, lateral corrosion (10-30 µm) was observed at the edge of the pattern after complete etching. This is because reactive ion beam etching is fast for A-site organic ions, but for elements with larger masses like B-site Pb ions or A-site Cs, especially in cases of large film thickness or small patterns (within 100 µm) (where the mask gap is small and etching is slow), a longer etching time is necessary to achieve complete etching. However, a longer etching time leads to lateral corrosion, which significantly impacts the dimensions of high-precision patterns (within 100 µm in side length). Therefore, when reactive ion beam etching reaches a certain stage, before lateral corrosion occurs, inductively coupled etching (ICE) is used. In ICE, Cl ions are highly effective at etching Pb, and the addition of a lower electrode during etching provides a vertically downward guiding effect on the reactive ions, allowing the remaining Pb to be etched away quickly without lateral corrosion.

Claims

1. A method for preparing halide perovskite array patterns using a mask fabricated by deep silicon etching technology, characterized in that, The following steps are involved: 1) Preparation of halide perovskite thin films; 2) Dry etching array pattern: A mask is placed on the halide perovskite film in step 1). The pattern formed by the mask corresponds to the halide perovskite array pattern. After etching using reactive ion etching and inductively coupled plasma etching, the mask is removed to form the halide perovskite film array pattern. Step 2), the method for fabricating the mask using deep silicon etching technology, includes the following steps: a. Pretreatment of silicon substrate; b. Coat the silicon substrate with photoresist after the pretreatment in step a, and after soft baking and resting, expose, develop and bake to form the desired pattern on the silicon substrate. c. Etch and clean the silicon substrate from step b to obtain the photomask; In step 2), the mask includes a first mask and a second mask, and the pattern formed by the combination of the first mask and the second mask corresponds to the halide perovskite array pattern; the reactive ion etching technology uses a reactive ion etching system, and the inductively coupled plasma etching technology uses an inductively coupled plasma etching system. In step 2), the etching method includes the following steps: a. First, cover the halide perovskite film with the first mask plate, fix it in position, place it in the reaction chamber of the reactive ion etching system, perform etching under vacuum conditions, and then take out the halide perovskite film and the first mask plate. b. Place the halide perovskite film and the first mask in the rapid sample injection chamber of the inductively coupled plasma etching system. Under vacuum conditions, transfer the halide perovskite film and the first mask to the etching chamber for etching. After etching is completed, transfer the halide perovskite film and the first mask back to the rapid sample injection chamber, remove them, and unload the first mask. c. Next, cover the halide perovskite film with a second mask. After positioning and fixing, place it in the reaction chamber of the reactive ion etching system and the etching chamber of the inductively coupled plasma etching system in sequence for etching. After etching is completed, the halide perovskite film and the second mask are transferred back to the rapid sample injection chamber, taken out, and the second mask is removed.

2. The method for preparing halide perovskite array patterns using a mask obtained by deep silicon etching technology as described in claim 1, characterized in that, In step 2), the etching conditions for step a are as follows: the etching gas is a combination atmosphere of CF4 and CHF3, the flow rate of CF4 is 20-40 sccm, the flow rate of CHF3 is 5-20 sccm, the gas pressure is 1-8 Pa, the plasma excitation radio frequency power is 50-100 W, and the etching time is 5-10 min. Step b etching conditions: upper electrode power 200-800 W, lower electrode power 20-80 W, etching gas is a combination atmosphere of chlorine and argon, gas pressure 2-6 mTorr, chlorine flow rate 10-15 sccm, argon flow rate 7-10 sccm, etching time 1-2 min.

3. The method for preparing halide perovskite array patterns using a mask obtained by deep silicon etching technology as described in claim 1, characterized in that, In step c, the etching process adopts the Bosch etching process, which specifically includes a deposition-first etching-second etching cycle. The deposition conditions are as follows: the main RF gas is C4F8 with a flow rate of 100-600 sccm; the secondary RF gas is C4F8 with a flow rate of 50-200 sccm; the total gas pressure in the cavity is set to 10-60 mTorr; and the deposition time is 0.5-3 s. First etching conditions: lower electrode power 50-90 W, main radio frequency gas SF6, flow rate 100-600 sccm, total chamber pressure 10-60 mTorr, etching time 0.5-3 s; Second etching conditions: lower electrode power 15-20 W, main RF gas SF6, flow rate 100-600 sccm, total chamber pressure 10-60 mTorr, etching time 0.5-3 s.

4. The method for preparing halide perovskite array patterns using a mask obtained by deep silicon etching technology as described in claim 3, characterized in that, In step c, the deposition-first etching-second etching cycle is 300-800 times. The main RF incident power used in the Bosch etching process cycle is 1500-2400 W, and the secondary RF incident power is 200-800 W.

5. The method for preparing halide perovskite array patterns using a mask obtained by deep silicon etching technology as described in claim 4, characterized in that, In step b, photoresist is coated onto the silicon substrate after the pretreatment in step a, and baked at a soft baking temperature of 90-110℃ for 8-12 minutes. After standing for 3-8 hours, the substrate is exposed, developed, and fixed, and then baked at a post-baking temperature of 110-130℃ for 12-18 minutes to form the desired pattern on the silicon substrate.

6. The method for preparing halide perovskite array patterns using a mask obtained by deep silicon etching technology as described in claim 5, characterized in that, In step a, silicon substrate pretreatment: the silicon substrate is cleaned with a cleaning solution under ultrasonic conditions and then dried; the thickness of the silicon substrate is 50-100 µm.

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