CN202643489U - Silicon wafer etching wastewater treatment system - Google Patents

Abstract

The utility model relates to a silicon wafer etching wastewater treatment system which comprises: A) a solid-liquid separator which is communicated with a working tank to receive the etching wastewater in the working tank thereby separating solid Si and residual liquid waste; B) an acid regeneration and silicon regeneration system used for receiving the residual liquid waste, wherein the acid regeneration and silicon regeneration system is in communication with the solid-liquid separator; C) an underpressure distillation device which is in communication with the acid regeneration and silicon regeneration system in order to receive a mixture which is derived from the acid regeneration and silicon regeneration system and contains the solid Si, gas HF and surplus H2SiF6 solution, and is also in communication with the solid-liquid separator; and D) an acidic absorbing tower which is in communication with the underpressure distillation device and the solid-liquid separator. By using the silicon wafer etching wastewater treatment system, the recycling of silicon wafer etching wastewater is realized, thereby reducing the consumption of acid corrosion solution, eliminating the generation of acid corrosion waste liquid, preventing the emission of toxic waste gas, protecting environment and increasing economic benefit.

Description

Silicon wafer etching Waste Water Treatment

Technical field

The utility model relates to the treatment system of chemical corrosion waste systems, specifically, relates to a kind of silicon wafer etching Waste Water Treatment.

Background technology

Generally be divided in manufacture of solar cells technique: clean (making herbs into wool), diffusion, the rear cleaning of diffusion, etching, PECVD, silk screen printing, sintering, classification and Detection and encapsulation before the diffusion, the Main Function of wherein making herbs into wool operation is to remove silicon chip surface cutting damage layer, forms the surperficial suede structure of light trapping structure; Etched Main Function is to remove the rear silicon chip of diffusion N-type silicon all around, with anticreep, at present, generally adopts two kinds of engraving methods of dry method and wet method.Making herbs into wool operation and wet etching use the acid corrosion of the mixing acid that comprises hydrofluoric acid and nitric acid etc. usually, and utilize the alkali of the alkali such as sodium hydroxide, potassium hydroxide to clean.The principle of acid corrosion is to use first HNO ₃Silicon oxidation is produced SiO ₂, and then by HF removal SiO ₂, chemical equation wherein is as follows:

3Si+4HNO ₃→3SiO ₂+4NO+2H ₂O

SiO ₂+6HF→H ₂SiF ₆+2H ₂O

Wherein etching solution also polishes and cleans solar cell surface, generally etching solution is injected on the solar cell or with solar cell and immerses in the etching solution.

Chinese patent application 201010577683.9 discloses a kind of corrosion wastewater treatment and treatment facility of silicon wafer, treatment process and the treatment system of the waste water of discharging when specifically disclosing with aqueous sodium hydroxide solution etching silicon wafer comprise and add acid in this etching waste water and separate out silicon-dioxide and silicon-dioxide is carried out solid-liquid separation.

So far also there is not open method to processing with the waste systems that produces behind the acid corrosion silicon wafer, in process of production, need to constantly discharge the waste systems that acid corrosion produces, add fresh acid etching solution, and the gas that produces in the cleaning course not be recycled.In the etching and making herbs into wool process of solar cell, need to use a large amount of acid etching solutions, and can produce a large amount of acid corrosion waste liquids and toxic gas NO like this, in described waste liquid, comprise HF, HNO ₃, H ₂SiF ₆, Si and water.From aspects such as the utilization of resources and environment protection, common process does not take full advantage of acid etching solution, has caused like this waste, has increased cost, has increased burden to environmental treatment simultaneously yet.

Wishing has a kind for the treatment of system, can process the waste systems that produces behind the acid corrosion silicon wafer, thereby so that acid etching solution be fully used.

The utility model content

Technical problem to be solved in the utility model provides a kind of silicon wafer etching Waste Water Treatment, so that acid etching solution is fully used.

Technical problem to be solved in the utility model can be solved by the following technical programs:

The utility model embodiment provides a kind of silicon wafer etching Waste Water Treatment, and it comprises:

A) thus be connected to receive the equipment for separating liquid from solid that etching waste water in the work nest is isolated solid Si and remaining waste liquid with work nest;

B) for the acid regeneration and the silicon regeneration system rapidly that receive described remaining waste liquid, described acid regeneration is connected with described equipment for separating liquid from solid with the silicon regeneration system rapidly;

C) be connected with the silicon regeneration system rapidly to receive that described acid regeneration and silicon regeneration system rapidly derive contains solid Si, gas HF and unnecessary H with described acid regeneration ₂SiF ₆The vacuum distillation apparatus of the mixture of solution, described vacuum distillation apparatus also are connected with described equipment for separating liquid from solid; And

D) the acid absorption tower that is connected with described vacuum distillation apparatus and work nest.

The utility model embodiment provides a kind of silicon wafer etching Waste Water Treatment, is to utilize HF solution and HNO in work nest ₃The H that discharges when the mixing acid etching solution of solution composition carries out etching to silicon wafer ₂SiF ₆Solution carries out cycling and reutilization, it is characterized in that, the H that discharges ₂SiF ₆Solution is separated out solid Si and sour gas HF by the electrolytic reaction groove electrolysis in acid regeneration and the silicon regeneration system rapidly, wherein, the solid Si that separates out is separated and recycling, imports to the HF solution in the mixing acid etching solution that forms recoverable in the described work nest after the sour gas HF that separates out is absorbed by water.

The utility model also provides a kind for the treatment of process that is applied to above-mentioned silicon wafer etching Waste Water Treatment, wherein, in work nest by HF solution and HNO ₃The mixing acid etching solution of solution composition is etched with silicon wafer and discharges etching waste water, includes solid Si and product H in the described etching waste water ₂SiF ₆Solution and the gas NO of first part, wherein, gas O in the gas NO of first part and the air ₂Further reaction produces the gas NO of first part ₂, it is characterized in that, the treating method comprises following steps:

A) isolate solid Si by equipment for separating liquid from solid, and obtain remaining waste liquid;

B) make H in the remaining waste liquid by the electrolytic reaction groove in acid regeneration and the silicon regeneration system rapidly ₂SiF ₆Solution generation electrolytic reaction is to obtain solid Si, gas HF; With

C) with gas HF and the gas NO of first part ₂Be collected in the water, to form HF solution and HNO ₃The mixing acid etching solution of solution composition;

Wherein, the solid Si that obtains of described electrolysis imports to and separates in the equipment for separating liquid from solid and recycling.

The utility model treatment system can realize the recycle of the acid etching solution of solar cell; thereby reduce the consumption of acid etching solution; eliminate the generation of acid corrosion waste liquid and avoid the discharging of poisonous fume; and improve battery efficiency owing to etching, polishing or cleaning processing are stablized, thereby the economic benefit of providing and protection of the environment.

Description of drawings

Fig. 1 is the synoptic diagram of the utility model silicon wafer etching Waste Water Treatment.

Embodiment

Below in conjunction with accompanying drawing the utility model embodiment is elaborated, so that the feature and advantage for the treatment of system of the present utility model are clearer, but the utility model is not limited to the embodiment that lists herein.

The utility model relates to a kind of silicon wafer etching Waste Water Treatment, is to utilize HF solution and HNO in work nest 1 ₃The H that discharges when the mixing acid etching solution of solution composition carries out etching to silicon wafer ₂SiF ₆Solution carries out cycling and reutilization, the H that discharges ₂SiF ₆Solution is separated out solid Si and sour gas HF by the electrolytic reaction groove 3-1 in acid regeneration and the silicon regeneration system rapidly 3 and 3-2 electrolysis, wherein, the solid Si that separates out is separated and recycling, again imports to after the sour gas HF that separates out is absorbed by water in the described work nest 1 with the HF solution in the mixing acid etching solution that forms recoverable.

1, in work nest 1, because of HF solution and HNO ₃The mixing acid etching solution of solution composition carries out etching to silicon wafer, and the reaction of carrying out is as follows:

3Si+4HNO ₃→3SiO ₂+4NO+2H ₂O 1)

3SiO ₂+18HF→3H ₂SiF ₆+6H ₂O 2)

Namely suc as formula 1) in, by HNO ₃Solution carries out etching to silicon wafer first, can obtain the gas NO of product first part and the solid SiO of first part ₂Then, suc as formula 2) in, continued and the solid SiO of first part that produces by HF solution ₂Or the SiO that is oxidized to of Si ₂Reaction generates product H ₂SiF ₆Solution so, constantly back and forth, carries out the etching of silicon wafer, like this, has obtained etching waste water in work nest 1, includes solid Si, solid SiO in the described etching waste water ₂, and product H ₂SiF ₆Solution and the gas NO of first part, wherein, the gas NO of first part is because in the work nest 1 that opens wide, gas O in the gas NO of first part and the air ₂Further reaction produces the gas NO of first part ₂, the gas NO of this first part ₂Import and be collected in the acid absorption tower 5 by extractor fan (not shown), the HNO in the formation work nest 1 in the mixing acid etching solution of recoverable ₃Solution.

2, receive etching waste water in the work nests 1 by equipment for separating liquid from solid 2, isolating solid Si and remaining waste liquid, and remaining waste liquid is imported in acid regeneration and the silicon regeneration system rapidly 3.

3, receive described remaining waste liquid by acid regeneration and silicon regeneration system rapidly 3, and by wherein electrolytic reaction groove 3-1 and 3-2 to H in the remaining waste liquid ₂SiF ₆Solution carries out electrolytic reaction, and to produce solid Si, gas HF, wherein, wherein electrolytic reaction comprises:

Cathodic reaction: H ₂SiF ₆+ 4e ^-(energising electrolysis)--＞Si+4F ^-+ 2HF

Anodic reaction: H ₂O (electrolysis)--＞2H ⁺+ 1/2O ₂↑+2e ^-

Wherein, product S i corresponding " silicon regeneration "; Product HF corresponding " acid regeneration ".

4, contain solid Si, gas HF and unnecessary H by what vacuum distillation apparatus 4 received described acid regenerations and 3 derivation of silicon regeneration system rapidly ₂SiF ₆The mixture of solution extracts the method for the gas HF in solution by underpressure distillation and also derive and contains solid Si, unnecessary H ₂SiF ₆The mixture of solution.Wherein, described vacuum distillation apparatus 4 is derived contains solid Si, unnecessary H ₂SiF ₆The mixture of solution is back in the equipment for separating liquid from solid 2 again, separates 2 by equipment for separating liquid from solid and goes out solid Si and H ₂SiF ₆Solution, solid Si is recycled, and H ₂SiF ₆Solution continues to import in acid regeneration and the silicon regeneration system rapidly 3 and carries out cycling and reutilization.

5, by acid absorption tower 5 with the gas NO of first part ₂, and be collected in the water by the gas HF that vacuum distillation apparatus 4 extracts, to form available HF solution and HNO in the work nest 1 ₃The mixing acid etching solution of solution composition.

Wherein, in described acid regeneration and silicon regeneration system rapidly 3, suc as formula 3), the HNO in the described remaining waste liquid ₃The solid Si reaction that solution and electrolysis produce generates second section gas NO, second section solid SiO ₂And import in the described vacuum distillation apparatus 4; In vacuum distillation apparatus 4, suc as formula 4), second section solid SiO ₂Generate H with gas HF reaction wherein ₂SiF ₆Solution; Suc as formula 5), gas O in second section gas NO and the air ₂Further reaction produces second section gas NO ₂, second section gas NO ₂Enter in the acid absorption tower 5 and absorbed the HNO that forms in the work nest 1 by water ₃Solution.

In described acid regeneration and silicon regeneration system rapidly 3:

3Si+4HNO ₃→3SiO ₂+4NO+2H ₂O 3)

In vacuum distillation apparatus 4:

3SiO ₂+18HF→3H ₂SiF ₆+6H ₂O 4)

NO+O ₂--＞NO ₂ 5)

As preferred embodiment of the present utility model, if equipment for separating liquid from solid 2 isolated remaining waste liquids import to the too many of acid regeneration and silicon regeneration system rapidly 3, or acid regeneration has little time to digest with silicon regeneration system rapidly 3, can be with the described equipment for separating liquid from solid 2 isolated HNO that contain ₃The etching waste water of solution imports in the vacuum distillation apparatus 4, and following series reaction is at HNO described in the described vacuum distillation apparatus 4 ₃Solution and described solid Si reaction generate third part solid SiO ₂, and third part gas NO, wherein, third part solid SiO ₂Further generate H with wherein gas HF reaction ₂SiF ₆Solution; And gas O in third part gas NO and the air ₂Further generated reactive gas third part NO ₂, third part gas NO ₂Enter in the acid absorption tower 5 and absorbed the HNO that forms in the work nest 1 by water ₃Solution.

3Si+4HNO ₃→3SiO ₂+4NO+2H ₂O

3SiO ₂+18HF→3H ₂SiF ₆+6H ₂O

NO+O ₂--＞NO ₂

Essential main following narration of the treatment process that the described silicon wafer etching of above preferred embodiment Waste Water Treatment adopts:

In work nest 1 by HF solution and HNO ₃The mixing acid etching solution of solution composition is etched with silicon wafer and discharges etching waste water, includes solid Si and product H in the described etching waste water ₂SiF ₆Solution and the gas NO of first part, wherein, gas O in the gas NO of first part and the air ₂Further reaction produces the gas NO of first part ₂, the treating method comprises following steps:

A) isolate solid Si by equipment for separating liquid from solid 1, and obtain remaining waste liquid;

B) make H in the remaining waste liquid by the electrolytic reaction groove 3-1 in acid regeneration and the silicon regeneration system rapidly 3 and 3-2 ₂SiF ₆Solution generation electrolytic reaction is to obtain solid Si, gas HF; With

C) with gas HF and the gas NO of first part ₂Be collected in the water, to form HF solution and HNO ₃The mixing acid etching solution of solution composition;

Wherein, the solid Si that obtains of described electrolysis imports to and separates in the equipment for separating liquid from solid 2 and recycling.The gas HF that described electrolysis obtains regathers in water after further extracting by vacuum distillation apparatus 4.The described gas NO of first part ₂Import and be collected in the water by extractor fan.Described steps A) separation in is undertaken by centrifugal separation or ultrafiltration process.

The utility model treatment system can realize the recycle of the acid etching solution of solar cell; thereby reduce the consumption of acid etching solution; eliminate the generation of acid corrosion waste liquid and avoid the discharging of poisonous fume; and improve battery efficiency owing to etching, polishing or cleaning processing are stablized, thereby the economic benefit of providing and protection of the environment.

Claims (1)

1. a silicon wafer etching Waste Water Treatment is characterized in that, described silicon wafer etching Waste Water Treatment comprises:

A) thus be connected to receive the equipment for separating liquid from solid that etching waste water in the work nest is isolated solid Si and remaining waste liquid with work nest;

B) for the acid regeneration and the silicon regeneration system rapidly that receive described remaining waste liquid, described acid regeneration is connected with described equipment for separating liquid from solid with the silicon regeneration system rapidly;

C) be connected with the silicon regeneration system rapidly to receive that described acid regeneration and silicon regeneration system rapidly derive contains solid Si, gas HF and unnecessary H with described acid regeneration ₂SiF ₆The vacuum distillation apparatus of the mixture of solution, described vacuum distillation apparatus also are connected with described equipment for separating liquid from solid; And

D) the acid absorption tower that is connected with described vacuum distillation apparatus and work nest.

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