Method for recycling boe waste liquid for semiconductor etching

Abstract

The application relates to a BOE waste liquid recycling method for semiconductor etching, and relates to the technical field of waste liquid treatment and resource recovery, and comprises the following steps: step S1, waste liquid pretreatment; step S2, silicon removal treatment; step S3, additive removal; step S4, activated carbon adsorption; and step S5, component adjustment and refining. The BOE waste liquid recycling method for semiconductor etching has more excellent additive and metal ion removal rates, and is used for faster panel BOE etching rates and better surface flatness.

Description

Technical Field

[0001] This invention relates to the field of waste liquid treatment and resource recycling technology, and in particular to a method for the resource recycling of BOE waste liquid used in semiconductor etching. Background Technology

[0002] In semiconductor manufacturing processes, BOE (buffered oxide) etchant is a critical consumable in chip fabrication due to its ability to precisely control the etching rate of silicon oxide. The BOE waste liquid generated after BOE etchant is used in the etching process of semiconductor components mainly consists of ammonium fluoride (BOE). It contains ammonia nitrogen and ammonium bifluoride (NH4HF2), as well as small amounts of fluorosilicate ions and sulfate ions. Direct discharge of these substances would severely impact the environment due to the ammonia nitrogen and fluoride ions, while also wasting resources. Therefore, the resource recovery and reuse of BOE waste liquid used in semiconductor etching is of great significance.

[0003] Existing methods for treating BOE wastewater mainly include neutralization, distillation, and adsorption, but all have significant drawbacks. Neutralization uses lime to neutralize the fluoride, producing calcium fluoride precipitate, which removes fluoride ions but cannot recover HF. The use of useful ingredients results in a serious waste of resources; and Precipitation requires landfill disposal, which can easily cause secondary pollution. Distillation recovers HF through heating, but it is energy-intensive, requires high-temperature operation, and the equipment is susceptible to corrosion by fluoride ions; moreover, it only recovers a portion of the components, failing to achieve multi-component resource utilization. Adsorption uses activated carbon or resin adsorption additives, but the adsorbent is easily saturated and requires frequent replacement, and the removal rate of metal ions is low; the BOE wastewater after adsorption treatment cannot meet the purity requirements for BOE used in panels.

[0004] In panel manufacturing (such as LCD and OLED), BOE is used to etch the glass substrate. The process requires high purity, high selectivity, and low surface roughness. Existing recycling methods for semiconductor BOE cannot meet these standards due to additive residues, resulting in semiconductor BOE waste liquid being treated as low-value waste.

[0005] To address the aforementioned issues, invention patent CN116395701A discloses a method for the resource-based treatment of BOE wastewater. This method allows for the selection of primary products—ammonium chloride or ammonium sulfate—based on the levels of impurities such as sulfate or chloride in the BOE wastewater. It can fully utilize the main components of BOE wastewater to produce sodium fluorosilicate, cryolite, and agricultural ammonium salts that meet relevant national standards, achieving high-value resource utilization. However, while this patent also addresses the resource-based treatment of BOE wastewater, it does not enable the recycling of components, and the recovery rate still needs further improvement. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of the prior art by providing a method for the resource recycling of BOE waste liquid used in semiconductor etching. Through the design of a composite treatment process, the efficient recycling and utilization of BOE waste liquid is achieved, solving the problems of resource waste, high treatment costs, and secondary pollution that exist in traditional methods. In particular, it breaks through the technical barrier of converting BOE waste liquid used in semiconductor etching into panel-grade BOE.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is: a method for resource recovery and reuse of BOE waste liquid used in semiconductor etching, comprising the following steps:

[0008] Step S1, Waste liquid pretreatment: The BOE waste liquid generated by semiconductor etching is filtered to remove solid particulate impurities, and the pretreated BOE waste liquid is obtained.

[0009] Step S2, Silicon Removal Treatment: Electronic grade liquid ammonia is vaporized and introduced into the pretreated BOE waste liquid. The pH value of the waste liquid is adjusted to 8.5-9.5. HF in the BOE waste liquid is converted into NH4F, and H2SiF6 is converted into NH4F and SiO2. The generated SiO2 is removed by filtration.

[0010] Step S3, Additive Removal: Add composite waste liquid treatment agent to the BOE waste liquid after silicon removal treatment, stir at 25-40℃ for 1-2 hours, and perform solid-liquid separation through a plate and frame filter press to obtain the additive-free waste liquid.

[0011] Step S4, Activated Carbon Adsorption: The activated carbon is soaked in electronic grade HF, then washed with ultrapure water, repeated three times and dried to remove metal ions from the activated carbon. The activated carbon is then packed into an adsorption fixed bed. The additive removal waste liquid is passed through the adsorption fixed bed at a certain rate to obtain BOE waste liquid after activated carbon adsorption treatment.

[0012] Step S5, Component Adjustment and Refining: The BOE waste liquid after activated carbon adsorption treatment is passed through an ion exchange resin column to remove any trace metal ions that may remain, further improving the purity of the BOE waste liquid; then the contents of HF and NH4F are tested, and based on the test results, appropriate amounts of hydrofluoric acid and ammonium fluoride are added to adjust the ratio of HF and NH4F to meet the requirements of panel BOE; ultrapure water is added to adjust the concentration of NH4F and HF to meet the specifications of panel BOE.

[0013] Preferably, the composite waste liquid treatment agent in step S3 comprises the following components in parts by weight: 1-3 parts polyferric sulfate, 2-4 parts modified activated carbon, 1-3 parts hydroxyapatite, 0.5-1.5 parts ethylenediaminetetraacetic acid, and 0.5-1.5 parts hydrogen peroxide.

[0014] Preferably, the average particle size of the hydroxyapatite is 50-80 nm.

[0015] Preferably, the polyferric sulfate has a weight-average molecular weight of 8,000-10,000.

[0016] Preferably, the modified activated carbon is 30% nitric acid activated modified activated carbon, and its preparation method includes the following steps: columnar activated carbon is used as a substrate, washed with water and dried, and then mixed with a 30% nitric acid solution. The reaction system temperature is raised to 90°C using an oil bath heating method, and the reaction is maintained under reflux for 3-5 hours. During the reaction, the volatilized nitric acid vapor is recovered through a condenser to reduce reagent loss and environmental pollution. After the reaction, the solid-liquid mixture is separated by suction filtration using a Buchner funnel while it is still hot. The activated carbon is repeatedly washed with 80°C deionized water until the pH value of the filtrate reaches 5.0-6.0. Then, the washed activated carbon is transferred to a muffle furnace and dried under a gradient temperature under a nitrogen protective atmosphere to obtain modified activated carbon.

[0017] Preferably, the columnar activated carbon has a particle size of 0.9-8 mm, an iodine value of 1100 mg / g, and a specific surface area of ​​1150 m² / g.

[0018] Preferably, the mass ratio of the columnar activated carbon to the nitric acid solution is 1:5.

[0019] Preferably, the gradient temperature drying process specifically involves: raising the temperature from room temperature to 110°C at a rate of 3-5°C / min and holding it at that temperature for 2 hours; then raising the temperature to 180°C at a rate of 5-8°C / min and holding it at that temperature for 3 hours.

[0020] Preferably, the mass ratio of the BOE waste liquid after silicon removal treatment to the composite waste liquid treatment agent in step S3 is 100:(0.2-1).

[0021] Preferably, the certain rate mentioned in step S4 is the liquid volume hourly space velocity. .

[0022] Preferably, the ion exchange resin column in step S5 consists of a first resin column and a second resin column connected in series; the first resin column is a D401 type chelating resin column, and the second resin column is an NKC-9 type strong acid cation resin column.

[0023] Due to the application of the above technical solution, the present invention has the following beneficial effects:

[0024] (1) The method for resource recycling of BOE waste liquid for semiconductor etching disclosed in this invention is simple, easy to operate, efficient and has a high finished product qualification rate. It has low dependence on equipment, is suitable for continuous large-scale production, and has high promotion and application value.

[0025] (2) The method for resource recycling of BOE waste liquid for semiconductor etching disclosed in this invention comprises the following components by weight: 1-3 parts polyferric sulfate, 2-4 parts modified activated carbon, 1-3 parts hydroxyapatite, 0.5-1.5 parts ethylenediaminetetraacetic acid, and 0.5-1.5 parts hydrogen peroxide. By rationally selecting the types and proportions of each component, the limitations of traditional single adsorption or chemical precipitation are overcome, forming a multi-mechanism synergistic system of "oxidation-flocculation-chelation-adsorption"; through the mutual cooperation and joint action of each component, a four-level linkage of "oxidation chain breaking → flocculation → chelation fixation → deep adsorption" is formed, which significantly improves the removal rate of additives and significantly reduces the metal ion concentration of the waste liquid after treatment. Hydrogen peroxide first oxidizes and decomposes long-chain organic additives into small molecule fragments, and the flocs formed by polyferric sulfate encapsulate and flocculate them, while the modified activated carbon completely adsorbs the residual small molecules through its rich pore structure and surface functional groups. ethylenediaminetetraacetic acid can react with the waste liquid in the BOE waste liquid. , , Trace amounts of metal ions form stable chelates, while hydroxyapatite further adsorbs the remaining metal ions through ion exchange; BOE waste liquid contains Colloidal and nano-sized solid particles flocculate under the action of polynuclear hydroxy complex ions generated by polyferric sulfate, forming large flocs that can be completely retained by plate and frame filter press, solving the problem of traditional filtration's inability to remove colloidal impurities. Its porous structure can adsorb unchelated free metal ions from EDTA, and through lattice substitution... , Heavy metals are fixed in the crystal structure.

[0026] (3) The method for resource recovery and reuse of BOE waste liquid for semiconductor etching disclosed in this invention, in step S2, adjusts the pH to 8.5-9.5 by electronic-grade liquid ammonia vaporization to achieve dual conversion: firstly, converting free HF into (Reaction formula:) ); secondly, to make Decomposition occurs ( ), generated The particles are easily removed by filtration, solving the problem of incomplete separation of silicon in traditional processes. Step S4 uses an activation process of immersion in electronic-grade HF followed by rinsing with ultrapure water, which can dissolve and remove the original calcium, magnesium and other metallic impurities of activated carbon, while forming targeted channels on the surface, effectively improving the adsorption capacity for residual organic additives.

[0027] (4) The method for resource recovery and reuse of BOE waste liquid for semiconductor etching disclosed in this invention uses 30% nitric acid activation modification to regulate the surface chemical properties and pore structure of activated carbon, effectively removing organic additives from semiconductor BOE waste liquid, and ultimately ensuring the stability of etching performance of recycled panel-grade BOE. In step S5, the design of using a D401 type chelating resin column and an NKC-9 type strong acid cation resin column in series breaks through the limitations of single resin column treatment. Through the synergistic mechanism of "targeted chelation-deep adsorption", the deep purification of trace metal ions in BOE waste liquid is achieved.

[0028] (5) The method for resource recycling of BOE waste liquid used in semiconductor etching disclosed in this invention, wherein the gradient temperature drying specifically involves: raising the temperature from room temperature to 110°C at a heating rate of 3-5°C / min and holding for 2 hours; then continuing to raise the temperature to 180°C at a heating rate of 5-8°C / min and holding for 3 hours. This gradient temperature drying process, through a layered strategy of "mild dewatering of free water - efficient dewatering of bound water", achieves deep drying while ensuring the structural integrity of activated carbon, making it a key supporting link for modified activated carbon to exert its efficient adsorption function. Detailed Implementation

[0029] The following description is intended to disclose the invention and enable those skilled in the art to implement it. The preferred embodiments described below are merely examples, and other obvious variations will occur to those skilled in the art.

[0030] Example 1: A method for resource recovery and reuse of BOE waste liquid used in semiconductor etching, comprising the following steps:

[0031] Step S1, Waste liquid pretreatment: The BOE waste liquid generated by semiconductor etching is filtered to remove solid particulate impurities, and the pretreated BOE waste liquid is obtained.

[0032] Step S2, Silicon Removal Treatment: Electronic grade liquid ammonia is vaporized and introduced into the pretreated BOE waste liquid. The pH value of the waste liquid is adjusted to 8.5, and HF in the BOE waste liquid is converted into NH4F, and H2SiF6 is converted into NH4F and SiO2. The generated SiO2 is removed by filtration.

[0033] Step S3, Additive Removal: Add composite waste liquid treatment agent to the BOE waste liquid after silicon removal treatment, stir at 25°C for 1 hour, and perform solid-liquid separation through a plate and frame filter press to obtain the additive-free waste liquid.

[0034] Step S4, Activated Carbon Adsorption: The activated carbon is soaked in electronic grade HF, then washed with ultrapure water, repeated three times and dried to remove metal ions from the activated carbon. The activated carbon is then packed into an adsorption fixed bed. The additive removal waste liquid is passed through the adsorption fixed bed at a certain rate to obtain BOE waste liquid after activated carbon adsorption treatment.

[0035] Step S5, Component Adjustment and Refining: The BOE waste liquid after activated carbon adsorption treatment is passed through an ion exchange resin column to remove any trace metal ions that may remain, further improving the purity of the BOE waste liquid; then the contents of HF and NH4F are tested, and based on the test results, appropriate amounts of hydrofluoric acid and ammonium fluoride are added to adjust the ratio of HF and NH4F to meet the requirements of panel BOE; ultrapure water is added to adjust the concentration of NH4F and HF to meet the specifications of panel BOE.

[0036] The composite waste liquid treatment agent in step S3 comprises the following components in parts by weight: 1 part polyferric sulfate, 2 parts modified activated carbon, 1 part hydroxyapatite, 0.5 parts ethylenediaminetetraacetic acid, and 0.5 parts hydrogen peroxide; the average particle size of the hydroxyapatite is 50 nm; and the weight-average molecular weight of the polyferric sulfate is 8000.

[0037] The modified activated carbon is 30% nitric acid activated modified activated carbon, and its preparation method includes the following steps: columnar activated carbon is used as a substrate, washed with water and dried, then mixed with a 30% (w / w) nitric acid solution. The reaction system temperature is raised to 90°C using an oil bath heating method, and the reaction is maintained under reflux for 3 hours. During the reaction, the volatilized nitric acid vapor is recovered through a condenser to reduce reagent loss and environmental pollution. After the reaction, the solid-liquid mixture is separated by suction filtration using a Buchner funnel while still hot. The activated carbon is repeatedly washed with 80°C deionized water until the pH value of the filtrate reaches the specified value. The activated carbon was then transferred to a muffle furnace and dried under a nitrogen protective atmosphere with a gradient temperature increase to obtain modified activated carbon. The columnar activated carbon had a particle size of 0.9-8 mm, an iodine value of 1100 mg / g, and a specific surface area of ​​1150 m² / g. The mass ratio of the columnar activated carbon to the nitric acid solution was 1:5. The gradient temperature increase drying process was as follows: the temperature was increased from room temperature to 110°C at a rate of 3°C / min and held for 2 hours; then the temperature was increased to 180°C at a rate of 5°C / min and held for 3 hours.

[0038] In step S3, the mass ratio of the BOE waste liquid after silicon removal treatment to the composite waste liquid treatment agent is 100:0.2; in step S4, the certain rate is the liquid volume hourly space velocity. The ion exchange resin column in step S5 consists of a first resin column and a second resin column connected in series; the first resin column is a D401 type chelating resin column, and the second resin column is an NKC-9 type strong acid cation resin column.

[0039] Example 2: A method for resource recovery and reuse of BOE waste liquid used in semiconductor etching, comprising the following steps:

[0040] Step S1, Waste liquid pretreatment: The BOE waste liquid generated by semiconductor etching is filtered to remove solid particulate impurities, and the pretreated BOE waste liquid is obtained.

[0041] Step S2, Silicon Removal Treatment: Electronic-grade liquid ammonia is vaporized and introduced into the pretreated BOE waste liquid. The pH value of the waste liquid is adjusted to 8.7, and HF in the BOE waste liquid is converted into NH4F, and H2SiF6 is converted into NH4F and SiO2. The generated SiO2 is removed by filtration.

[0042] Step S3, Additive Removal: Add composite waste liquid treatment agent to the BOE waste liquid after silicon removal treatment, stir at 30°C for 1.2 hours, and then perform solid-liquid separation through a plate and frame filter press to obtain the additive-free waste liquid.

[0043] Step S4, Activated Carbon Adsorption: The activated carbon is soaked in electronic grade HF, then washed with ultrapure water, repeated three times and dried to remove metal ions from the activated carbon. The activated carbon is then packed into an adsorption fixed bed. The additive removal waste liquid is passed through the adsorption fixed bed at a certain rate to obtain BOE waste liquid after activated carbon adsorption treatment.

[0044] Step S5, Component Adjustment and Refining: The BOE waste liquid after activated carbon adsorption treatment is passed through an ion exchange resin column to remove any trace metal ions that may remain, further improving the purity of the BOE waste liquid; then the contents of HF and NH4F are tested, and based on the test results, appropriate amounts of hydrofluoric acid and ammonium fluoride are added to adjust the ratio of HF and NH4F to meet the requirements of panel BOE; ultrapure water is added to adjust the concentration of NH4F and HF to meet the specifications of panel BOE.

[0045] The composite waste liquid treatment agent in step S3 comprises the following components in parts by weight: 1.5 parts polyferric sulfate, 2.5 parts modified activated carbon, 1.5 parts hydroxyapatite, 0.8 parts ethylenediaminetetraacetic acid, and 0.8 parts hydrogen peroxide; the average particle size of the hydroxyapatite is 60 nm; and the weight-average molecular weight of the polyferric sulfate is 8500.

[0046] The modified activated carbon is 30% nitric acid activated modified activated carbon, and its preparation method includes the following steps: columnar activated carbon is used as a substrate, washed with water and dried, then mixed with a 30% (w / w) nitric acid solution. The reaction system temperature is raised to 90°C using an oil bath heating method, and the reaction is maintained under reflux for 3.5 hours. During the reaction, the volatilized nitric acid vapor is recovered through a condenser to reduce reagent loss and environmental pollution. After the reaction, the solid-liquid mixture is separated by suction filtration using a Buchner funnel while still hot. The activated carbon is repeatedly washed with 80°C deionized water until the pH of the filtrate reaches 5.3. Then, the washed activated carbon is transferred to a muffle furnace and heated under a nitrogen protective atmosphere. Modified activated carbon was obtained by gradient heating and drying under ambient temperature. The columnar activated carbon had a particle size of 0.9-8 mm, an iodine value of 1100 mg / g, and a specific surface area of ​​1150 m² / g. The mass ratio of the columnar activated carbon to nitric acid solution was 1:5. The gradient heating and drying process specifically involved heating from room temperature to 110°C at a rate of 3.5°C / min and holding at that temperature for 2 hours; then heating to 180°C at a rate of 6°C / min and holding at that temperature for 3 hours. In step S3, the mass ratio of the BOE waste liquid after silicon removal treatment to the composite waste liquid treatment agent was 100:0.5. In step S4, the certain rate was the liquid hourly space velocity (LHSV). The ion exchange resin column in step S5 consists of a first resin column and a second resin column connected in series; the first resin column is a D401 type chelating resin column, and the second resin column is an NKC-9 type strong acid cation resin column.

[0047] Example 3: A method for resource recovery and reuse of BOE waste liquid used in semiconductor etching, comprising the following steps:

[0048] Step S1, Waste liquid pretreatment: The BOE waste liquid generated by semiconductor etching is filtered to remove solid particulate impurities, and the pretreated BOE waste liquid is obtained.

[0049] Step S2, silicon removal treatment: Electronic grade liquid ammonia is vaporized and introduced into the pretreated BOE waste liquid. The pH value of the waste liquid is adjusted to 9, and HF in the BOE waste liquid is converted into NH4F, and H2SiF6 is converted into NH4F and SiO2. The generated SiO2 is removed by filtration.

[0050] Step S3, Additive Removal: Add composite waste liquid treatment agent to the BOE waste liquid after silicon removal treatment, stir at 33°C for 1.5 hours, and then perform solid-liquid separation through a plate and frame filter press to obtain the additive-free waste liquid.

[0051] Step S4, Activated Carbon Adsorption: The activated carbon is soaked in electronic grade HF, then washed with ultrapure water, repeated three times and dried to remove metal ions from the activated carbon. The activated carbon is then packed into an adsorption fixed bed. The additive removal waste liquid is passed through the adsorption fixed bed at a certain rate to obtain BOE waste liquid after activated carbon adsorption treatment.

[0052] Step S5, Component Adjustment and Refining: The BOE waste liquid after activated carbon adsorption treatment is passed through an ion exchange resin column to remove any trace metal ions that may remain, further improving the purity of the BOE waste liquid; then the contents of HF and NH4F are tested, and based on the test results, appropriate amounts of hydrofluoric acid and ammonium fluoride are added to adjust the ratio of HF and NH4F to meet the requirements of panel BOE; ultrapure water is added to adjust the concentration of NH4F and HF to meet the specifications of panel BOE.

[0053] The composite waste liquid treatment agent in step S3 comprises the following components by weight: 2 parts polyferric sulfate, 3 parts modified activated carbon, 2 parts hydroxyapatite, 1 part ethylenediaminetetraacetic acid, and 1 part hydrogen peroxide; the average particle size of the hydroxyapatite is 65 nm; and the weight-average molecular weight of the polyferric sulfate is 9000.

[0054] The modified activated carbon is 30% nitric acid activated modified activated carbon, and its preparation method includes the following steps: columnar activated carbon is used as a substrate, washed with water and dried, then mixed with a 30% (w / w) nitric acid solution. The reaction system temperature is raised to 90°C using an oil bath heating method, and the reaction is maintained under reflux for 4 hours. During the reaction, the volatilized nitric acid vapor is recovered through a condenser to reduce reagent loss and environmental pollution. After the reaction, the solid-liquid mixture is separated by suction filtration using a Buchner funnel while still hot. The activated carbon is repeatedly washed with 80°C deionized water until the pH value of the filtrate reaches the specified value. 5.5; Next, the washed activated carbon is transferred to a muffle furnace and dried under a nitrogen protective atmosphere with gradient heating to obtain modified activated carbon; the particle size of the columnar activated carbon is 0.9-8 mm, the iodine value is 1100 mg / g, and the specific surface area is 1150 m² / g; the mass ratio of the columnar activated carbon to nitric acid solution is 1:5; the gradient heating drying is specifically as follows: the temperature is increased from room temperature to 110°C at a heating rate of 4°C / min and held for 2 hours; then the temperature is increased to 180°C at a heating rate of 6.5°C / min and held for 3 hours.

[0055] In step S3, the mass ratio of the BOE waste liquid after silicon removal treatment to the composite waste liquid treatment agent is 100:0.7; in step S4, the certain rate is the liquid volume hourly space velocity. The ion exchange resin column in step S5 consists of a first resin column and a second resin column connected in series; the first resin column is a D401 type chelating resin column, and the second resin column is an NKC-9 type strong acid cation resin column.

[0056] Example 4: A method for resource recovery and reuse of BOE waste liquid used in semiconductor etching, comprising the following steps:

[0057] Step S1, Waste liquid pretreatment: The BOE waste liquid generated by semiconductor etching is filtered to remove solid particulate impurities, and the pretreated BOE waste liquid is obtained.

[0058] Step S2, Silicon Removal Treatment: Electronic grade liquid ammonia is vaporized and introduced into the pretreated BOE waste liquid. The pH value of the waste liquid is adjusted to 9.3, and HF in the BOE waste liquid is converted into NH4F, and H2SiF6 is converted into NH4F and SiO2. The generated SiO2 is removed by filtration.

[0059] Step S3, Additive Removal: Add composite waste liquid treatment agent to the BOE waste liquid after silicon removal treatment, stir at 38°C for 1.8 hours, and then perform solid-liquid separation through a plate and frame filter press to obtain the additive-free waste liquid.

[0060] Step S4, Activated Carbon Adsorption: The activated carbon is soaked in electronic grade HF, then washed with ultrapure water, repeated three times and dried to remove metal ions from the activated carbon. The activated carbon is then packed into an adsorption fixed bed. The additive removal waste liquid is passed through the adsorption fixed bed at a certain rate to obtain BOE waste liquid after activated carbon adsorption treatment.

[0061] Step S5, Component Adjustment and Refining: The BOE waste liquid after activated carbon adsorption treatment is passed through an ion exchange resin column to remove any trace metal ions that may remain, further improving the purity of the BOE waste liquid; then the contents of HF and NH4F are tested, and based on the test results, appropriate amounts of hydrofluoric acid and ammonium fluoride are added to adjust the ratio of HF and NH4F to meet the requirements of panel BOE; ultrapure water is added to adjust the concentration of NH4F and HF to meet the specifications of panel BOE.

[0062] The composite waste liquid treatment agent in step S3 comprises the following components by weight: 2.5 parts polyferric sulfate, 3.5 parts modified activated carbon, 2.5 parts hydroxyapatite, 1.3 parts ethylenediaminetetraacetic acid, and 1.3 parts hydrogen peroxide; the average particle size of the hydroxyapatite is 75 nm; and the weight-average molecular weight of the polyferric sulfate is 9500.

[0063] The modified activated carbon is 30% nitric acid activated modified activated carbon, and its preparation method includes the following steps: columnar activated carbon is used as a substrate, washed with water and dried, then mixed with a 30% (w / w) nitric acid solution. The reaction system temperature is raised to 90°C using an oil bath heating method, and the reaction is maintained under reflux for 4.5 hours. During the reaction, the volatilized nitric acid vapor is recovered through a condenser to reduce reagent loss and environmental pollution. After the reaction, the solid-liquid mixture is separated by suction filtration using a Buchner funnel while still hot. The activated carbon is repeatedly washed with 80°C deionized water until the pH value of the filtrate reaches the specified value. 5.8; Next, the washed activated carbon is transferred to a muffle furnace and dried under a nitrogen protective atmosphere with gradient heating to obtain modified activated carbon; the particle size of the columnar activated carbon is 0.9-8 mm, the iodine value is 1100 mg / g, and the specific surface area is 1150 m² / g; the mass ratio of the columnar activated carbon to nitric acid solution is 1:5; the gradient heating drying is specifically as follows: the temperature is increased from room temperature to 110°C at a heating rate of 4.5°C / min and held for 2 hours; then the temperature is increased to 180°C at a heating rate of 7.5°C / min and held for 3 hours.

[0064] In step S3, the mass ratio of the BOE waste liquid after silicon removal treatment to the composite waste liquid treatment agent is 100:0.9; in step S4, the certain rate is the liquid volume hourly space velocity. The ion exchange resin column in step S5 consists of a first resin column and a second resin column connected in series; the first resin column is a D401 type chelating resin column, and the second resin column is an NKC-9 type strong acid cation resin column.

[0065] Example 5: A method for resource recovery and reuse of BOE waste liquid used in semiconductor etching, comprising the following steps:

[0066] Step S1, Waste liquid pretreatment: The BOE waste liquid generated by semiconductor etching is filtered to remove solid particulate impurities, and the pretreated BOE waste liquid is obtained.

[0067] Step S2, Silicon Removal Treatment: Electronic grade liquid ammonia is vaporized and introduced into the pretreated BOE waste liquid. The pH value of the waste liquid is adjusted to 9.5, and HF in the BOE waste liquid is converted into NH4F, and H2SiF6 is converted into NH4F and SiO2. The generated SiO2 is removed by filtration.

[0068] Step S3, Additive Removal: Add composite waste liquid treatment agent to the BOE waste liquid after silicon removal treatment, stir at 40°C for 2 hours, and then perform solid-liquid separation through a plate and frame filter press to obtain the additive-free waste liquid.

[0069] Step S4, Activated Carbon Adsorption: The activated carbon is soaked in electronic grade HF, then washed with ultrapure water, repeated three times and dried to remove metal ions from the activated carbon. The activated carbon is then packed into an adsorption fixed bed. The additive removal waste liquid is passed through the adsorption fixed bed at a certain rate to obtain BOE waste liquid after activated carbon adsorption treatment.

[0070] Step S5, Component Adjustment and Refining: The BOE waste liquid after activated carbon adsorption treatment is passed through an ion exchange resin column to remove any trace metal ions that may remain, further improving the purity of the BOE waste liquid; then the contents of HF and NH4F are tested, and based on the test results, appropriate amounts of hydrofluoric acid and ammonium fluoride are added to adjust the ratio of HF and NH4F to meet the requirements of panel BOE; ultrapure water is added to adjust the concentration of NH4F and HF to meet the specifications of panel BOE.

[0071] The composite waste liquid treatment agent in step S3 comprises the following components in parts by weight: 3 parts polyferric sulfate, 4 parts modified activated carbon, 3 parts hydroxyapatite, 1.5 parts ethylenediaminetetraacetic acid, and 1.5 parts hydrogen peroxide; the average particle size of the hydroxyapatite is 80 nm; and the weight-average molecular weight of the polyferric sulfate is 10,000.

[0072] The modified activated carbon is 30% nitric acid activated modified activated carbon, and its preparation method includes the following steps: columnar activated carbon is used as a substrate, washed with water and dried, then mixed with a 30% (w / w) nitric acid solution. The reaction system temperature is raised to 90°C using an oil bath heating method, and the reaction is maintained under reflux for 5 hours. During the reaction, the volatilized nitric acid vapor is recovered through a condenser to reduce reagent loss and environmental pollution. After the reaction, the solid-liquid mixture is separated by suction filtration using a Buchner funnel while still hot. The activated carbon is repeatedly washed with 80°C deionized water until the pH value of the filtrate reaches the specified value. The activated carbon was then transferred to a muffle furnace and dried under a nitrogen protective atmosphere with a gradient temperature increase to obtain modified activated carbon. The columnar activated carbon had a particle size of 0.9-8 mm, an iodine value of 1100 mg / g, and a specific surface area of ​​1150 m² / g. The mass ratio of the columnar activated carbon to the nitric acid solution was 1:5. The gradient temperature increase drying process was as follows: the temperature was increased from room temperature to 110°C at a rate of 5°C / min and held for 2 hours; then the temperature was increased to 180°C at a rate of 8°C / min and held for 3 hours.

[0073] In step S3, the mass ratio of the BOE waste liquid after silicon removal treatment to the composite waste liquid treatment agent is 100:1; in step S4, the certain rate is the liquid volume hourly space velocity. The ion exchange resin column in step S5 consists of a first resin column and a second resin column connected in series; the first resin column is a D401 type chelating resin column, and the second resin column is an NKC-9 type strong acid cation resin column.

[0074] Comparative Example 1

[0075] This example is basically the same as Example 1, except that an equal amount of activated carbon is used instead of modified activated carbon; and no hydroxyapatite is added.

[0076] Comparative Example 2

[0077] This example is basically the same as Example 1, except that the step of using an ion exchange resin column for treatment is omitted, and an equal amount of hydroxyapatite is used instead of ethylenediaminetetraacetic acid.

[0078] The following test methods were used to conduct relevant performance tests on the BOE waste liquid products obtained from the resource recovery and reuse methods for semiconductor etching in various cases. The test results are shown in Table 1. The test methods are as follows:

[0079] Experimental materials

[0080] Semiconductor BOE waste liquid: taken from a 12-inch wafer fab, main components: 9.2wt%, 20.5wt%, 4.1wt%, 650ppm; 178ppb.

[0081] Experimental methods

[0082] TOC removal rate: Reference The method of "Determination of Total Organic Carbon (TOC) in Water by Non-dispersive Infrared Absorption" was used to detect the TOC in wastewater before and after treatment and to calculate the removal rate.

[0083] Metal ion removal rate: Referring to GB / T 30903-2014 "Determination of impurity elements in inorganic chemical products by inductively coupled plasma mass spectrometry", the concentration of metal ions in the waste liquid before and after treatment was detected, and the removal rate was calculated; here, the removal rate of zinc ions is used as an example to measure the metal ion removal rate.

[0084] Etching rate: Glass substrates were treated under the same conditions (temperature 25℃, etching time 60s), and the etching depth was measured using a white light interferometer (film thickness gauge, accuracy 0.1Å) to calculate the etching rate.

[0085] Surface roughness: GB T 1031-1995 "Surface roughness parameters and their values" was selected as the standard. For each example and comparative example, three identical glass substrates were etched at the same time and temperature (temperature 25℃, etching time 60s) while keeping the etching pattern the same. After etching, the surface roughness of the etched pattern was tested and the average value was taken.

[0086] Table 1

[0087]

[0088] As can be seen from Table 1, the resource recycling method for BOE waste liquid used in semiconductor etching of the various embodiments of the present invention has better additive and metal ion removal rates than the comparative example, and the BOE etching rate of the panel is faster and the surface smoothness is better; the combined use of modified activated carbon, hydroxyapatite, ion exchange resin column and ethylenediaminetetraacetic acid is beneficial to improving the above performance.

[0089] The above embodiments are only for illustrating the technical concept and features of the present invention. Their purpose is to enable those skilled in the art to understand the content of the present invention and implement it accordingly. They should not be used to limit the scope of protection of the present invention. All equivalent changes or modifications made in accordance with the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A method for the resource recovery and reuse of BOE waste liquid used in semiconductor etching, characterized in that, Includes the following steps: Step S1, Waste liquid pretreatment: The BOE waste liquid generated by semiconductor etching is filtered to remove solid particulate impurities, and the pretreated BOE waste liquid is obtained. Step S2, Silicon Removal Treatment: Electronic grade liquid ammonia is vaporized and introduced into the pretreated BOE waste liquid. The pH value of the waste liquid is adjusted to 8.5-9.

5. HF in the BOE waste liquid is converted into NH4F, and H2SiF6 is converted into NH4F and SiO2. The generated SiO2 is removed by filtration. Step S3, Additive Removal: Add a composite waste liquid treatment agent to the BOE waste liquid after silicon removal treatment, stir at 25-40℃ for 1-2 hours, and perform solid-liquid separation through a plate and frame filter press to obtain the additive-free waste liquid; the composite waste liquid treatment agent includes the following components by weight: 1-3 parts polyferric sulfate, 2-4 parts modified activated carbon, 1-3 parts hydroxyapatite, 0.5-1.5 parts ethylenediaminetetraacetic acid, and 0.5-1.5 parts hydrogen peroxide; Step S4, Activated Carbon Adsorption: The activated carbon is soaked in electronic grade HF, then washed with ultrapure water, repeated three times and dried to remove metal ions from the activated carbon. The activated carbon is then packed into an adsorption fixed bed. The additive removal waste liquid is passed through the adsorption fixed bed at a certain rate to obtain BOE waste liquid after activated carbon adsorption treatment. Step S5, Component Adjustment and Refining: The BOE waste liquid after activated carbon adsorption treatment is passed through an ion exchange resin column to remove any trace metal ions that may remain, further improving the purity of the BOE waste liquid; then the contents of HF and NH4F are tested, and based on the test results, appropriate amounts of hydrofluoric acid and ammonium fluoride are added to adjust the ratio of HF and NH4F to meet the requirements of panel BOE; ultrapure water is added to adjust the concentration of NH4F and HF to meet the specifications of panel BOE. The modified activated carbon is a 30% nitric acid activated modified activated carbon, and its preparation method includes the following steps: columnar activated carbon is used as a substrate, washed with water and dried, and then mixed with a 30% nitric acid solution. The reaction system temperature is raised to 90°C using an oil bath heating method, and the reaction is maintained under reflux for 3-5 hours. During the reaction, the volatilized nitric acid vapor is recovered through a condenser to reduce reagent loss and environmental pollution. After the reaction, the solid-liquid mixture is separated by suction filtration using a Buchner funnel while it is still hot. The activated carbon is repeatedly washed with 80°C deionized water until the pH value of the filtrate reaches 5.0-6.

0. Then, the washed activated carbon is transferred to a muffle furnace and dried under a gradient temperature under a nitrogen protective atmosphere to obtain the modified activated carbon.

2. The method for resource recovery and reuse of BOE waste liquid for semiconductor etching according to claim 1, characterized in that, The average particle size of the hydroxyapatite is 50-80 nm.

3. The method for resource recovery and reuse of BOE waste liquid for semiconductor etching according to claim 1, characterized in that, The weight-average molecular weight of the polyferric sulfate is 8000-10000.

4. The method for resource recovery and reuse of BOE waste liquid for semiconductor etching according to claim 1, characterized in that, The columnar activated carbon has a particle size of 0.9-8 mm, an iodine value of 1100 mg / g, and a specific surface area of ​​1150 m². 2 / g.

5. The method for resource recovery and reuse of BOE waste liquid for semiconductor etching according to claim 1, characterized in that, The mass ratio of the columnar activated carbon to the nitric acid solution is 1:5; the gradient temperature drying process specifically involves: raising the temperature from room temperature to 110°C at a rate of 3-5°C / min and holding it at that temperature for 2 hours; then raising the temperature to 180°C at a rate of 5-8°C / min and holding it at that temperature for 3 hours.

6. The method for resource recovery and reuse of BOE waste liquid for semiconductor etching according to claim 1, characterized in that, The mass ratio of the BOE waste liquid after silicon removal treatment to the composite waste liquid treatment agent in step S3 is 100:(0.2-1).

7. The method for resource recovery and reuse of BOE waste liquid for semiconductor etching according to claim 1, characterized in that, The certain rate mentioned in step S4 is the liquid volume hourly space velocity (LHSV) of 0.5-2 h⁻ 1 .

8. The method for resource recovery and reuse of BOE waste liquid for semiconductor etching according to claim 1, characterized in that, The ion exchange resin column in step S5 consists of a first resin column and a second resin column connected in series; the first resin column is a D401 type chelating resin column, and the second resin column is an NKC-9 type strong acid cation resin column.

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