A kind of etching method of the black silicon wafer of polycrystalline
Technical field
The present invention relates to silicon solar cell field more particularly to a kind of etching methods of the black silicon wafer of polycrystalline.
Background technique
Silicon solar cell develops relative maturity in area of solar cell, and practicability is stronger, nowadays has been commercialized for many years.
And with the continuous development of technology, optoelectronic transformation efficiency is also correspondingly improved, and cost also constantly declines.It is increasingly exhausted in fossil energy
Today, accounting of the solar battery in the social consumption energy will also increase year by year.
The production technology of wet process black silicon solar cell piece specifically includes that making herbs into wool, diffusion, etching, plated film, printing and sintering
Deng.And making herbs into wool is the first step of silicon solar cell preparation, is also very important a step.Currently, silicon solar cell making herbs into wool work
Skill mainly has reactive ion etching method (RIE), mechanical carving groove technology, laser etching techniques, honeycomb flannelette technology, metal inducement wet
Black silicon of method (MCCE) etc..And MCCE method is to use one of the most common type method in current industry.The main flow of its technique is alkali
It washes, pickling, heavy silver, borehole, the desilverization, pickling, reaming, alkali cleaning, pickling, drying etc., also adulterates the step of numerous washings among these
Suddenly.Wherein, pickling is to neutralize remaining lye and organic matter etc., and what is walked under the influence of avoiding is silver-plated;This silver-plated step is unquestionable
It is crucial one of step, it is therefore an objective to form reaction site;Next is exactly that borehole is carried out on silver-colored site, is wanted after borehole
With hydrogen peroxide and ammonia spirit come the desilverization, HF/HNO is used after the desilverization3Carry out reaming.Remaining acid solution KOH+H2O2+NH4OH
Wash, at the same to remove silicon chip surface burr and small structure.Remaining lye is removed in following pickling, finally washing drying.Work
Skill process is various many and diverse, and each step can all influence final efficiency.Especially in the reaction process of reaming, HF/HNO3It is sent out in system
Raw chemical reaction is mainly made of oxidation reaction and dissolution reaction.Si is oxidized to SiO as strong oxidizer by nitric acid2, SiO2's
Form the corrosion that can prevent nitric acid again.And hydrofluoric acid can be by SiO2Corrosion, thus soluble in water.The reaction of generation is first in silicon wafer
At tomography or complex centre, that is, intensifying can lower reaction site.Reaction can be simultaneously to horizontal and vertical development.But a period of time
Afterwards, longitudinally intensifying can get higher, therefore reaction speed can be slack-off, eventually be lower than lateral velocity.And the silver nanoparticle in the system
Particle just plays the role of reaction site, and reaction rate herein is more much higher than the place that no silver nano-grain adheres to, because
This can generate empty shape nanostructure.And this structure can reduce reflectivity, to improve the efficiency of battery.However, this de-
Silver and the process of this two steps making herbs into wool of reaming are longer, and cost also increases unavoidably.Moreover, the increase of process also will increase simultaneously
Such as risk of greasy dirt, impurity pollution.Therefore, the making herbs into wool efficiency for how improving process for etching is of great significance.
Summary of the invention
In view of this, technical problem to be solved by the present invention lies in a kind of etching method of black silicon wafer of polycrystalline is provided, this
The method that invention provides in same system by carrying out the desilverization and expanding treatment, the system for improving making herbs into wool efficiency, and obtaining
The silicon wafer suede of suede is preferable.
The present invention provides a kind of etching methods of the black silicon wafer of polycrystalline, comprising:
1) desilverization expanding treatment will be carried out in the silicon wafer merging mixed solution of borehole, obtains the silicon wafer of reaming;
Wherein, the mixed solution is the mixed of mixed solution, ammonium fluoride and the nitrate composition that ammonium fluoride and nitric acid form
Close mixed solution, ammonium nilrite and the hydrogen of solution, the mixed solution of ammonium fluoride and nitrous acid composition, ammonium nitrate and hydrofluoric acid composition
Fluoric acid composition mixed solution, ammonium nitrate and ammonium fluoride composition mixed solution, ammonium nilrite and ammonium fluoride composition solution or
The solution of ammonium ceric nitrate and ammonium fluoride composition;
2) silicon wafer of desilverization reaming is subjected to subsequent processing, obtains the black silicon wafer of polycrystalline of making herbs into wool.
Preferably, the temperature of the step 1) processing is 6~30 DEG C.
Preferably, the temperature of the step 1) processing is 10~25 DEG C.
Preferably, the mass fraction of solute is 15%~45% in the mixed solution.
Preferably, the mass fraction of solute is 20%~30% in the mixed solution.
Preferably, in the mixed solution, just with fluorine ion and just, the molar ratio with nitrate ion is 1: (1~5);
In the mixed solution, just with fluorine ion and just, the molar ratio with nitrite ion is 1: (1~5).
Preferably, in the mixed solution, the molar ratio of fluorine ion, nitrate ion and ammonium ion is 1: (2~3);
In the mixed solution, just with fluorine ion and just, the molar ratio with nitrite ion is 1: (2~3).
Preferably, the time of the step 1) processing is 60~600 seconds.
Preferably, the silicon wafer of the borehole is prepared in accordance with the following methods: will successively pass through alkali cleaning, acid to making herbs into wool silicon wafer
It washes, heavy silver-colored and borehole processing, obtains the silicon wafer of borehole.
Preferably, the step 2) is specially and the silicon wafer after reaming is successively passed through alkali cleaning, pickling, washing and drying etc. to obtain
To the silicon wafer of making herbs into wool.
Compared with prior art, the present invention provides a kind of etching methods of the black silicon wafer of polycrystalline, by first by borehole
Silicon wafer, which is placed in mixed solution, carries out desilverization expanding treatment, obtains the silicon wafer of reaming;Then the silicon wafer of reaming is carried out further
Processing, obtains the black silicon wafer of polycrystalline of making herbs into wool.Wherein, the present invention pass through select the mixed solution for ammonium fluoride and nitric acid composition
Mixed solution, ammonium nitrate and the hydrogen that mixed solution, ammonium fluoride and the nitrous acid of mixed solution, ammonium fluoride and nitrate composition form
The mixing that the mixed solution or ammonium nilrite of fluoric acid composition and mixed solution, ammonium nitrate and the ammonium fluoride of hydrofluoric acid composition form is molten
The solution of liquid, the solution of ammonium nilrite and ammonium fluoride composition or ammonium ceric nitrate and ammonium fluoride composition;So that system of the invention
Velvet figures method can realize two processing steps of the desilverization and reaming simultaneously in a reaction system, and the silicon wafer of obtained making herbs into wool
Flannelette is preferable;The process flow of reaction is not shortened, and reduces the cost of silicon wafer wool making.
Detailed description of the invention
Fig. 1 is the amplification appearance number figure of the silicon wafer after the making herbs into wool that embodiment 1 is prepared;
Fig. 2 is the appearance number figure of the silicon wafer after the making herbs into wool that embodiment 1 is prepared;
Fig. 3 is the scanning electron microscope (SEM) photograph of the silicon wafer after the making herbs into wool that embodiment 1 is prepared;
Fig. 4 is the appearance number figure of the silicon wafer after the making herbs into wool that comparative example 1 is prepared;
Fig. 5 is the flow chart under standard technology;
Fig. 6 provides the process flow chart of preparation method for the present invention.
Specific embodiment
The present invention provides a kind of etching methods of the black silicon wafer of polycrystalline, comprising:
1) desilverization expanding treatment will be carried out in the silicon wafer merging mixed solution of borehole, obtains the silicon wafer of reaming;
Wherein, the mixed solution is the mixed of mixed solution, ammonium fluoride and the nitrate composition that ammonium fluoride and nitric acid form
Close solution, ammonium fluoride and nitrous acid composition mixed solution, ammonium nitrate and hydrofluoric acid composition mixed solution or ammonium nilrite and
The mixed solution of hydrofluoric acid composition;
2) silicon wafer of reaming is further processed, obtains the black silicon wafer of polycrystalline of making herbs into wool.
According to the present invention, the present invention will carry out desilverization expanding treatment in the silicon wafer merging mixed solution of borehole, obtain reaming
Silicon wafer;Wherein, the temperature of the processing is preferably 6~30 DEG C, more preferably 10~25 DEG C, most preferably 15~20 DEG C;Institute
The time for stating processing is preferably 60~600 seconds, more preferably 100~400 seconds, most preferably 150~300 seconds;The mixing is molten
Liquid is preferably that the mixing that the mixed solution is mixed solution, ammonium fluoride and nitrous acid composition that ammonium fluoride and nitric acid form is molten
Mixed solution, ammonium nitrate and the ammonium fluoride that mixed solution, ammonium nilrite and the hydrofluoric acid of liquid, ammonium nitrate and hydrofluoric acid composition form
The solution of the mixed solution of composition, the solution of ammonium nilrite and ammonium fluoride composition or ammonium ceric nitrate and ammonium fluoride composition, more preferably
The mixed solution formed for ammonium fluoride and ammonium nitrate;In the mixed solution, just with fluorine ion and just rubbing with nitrate ion
You are than being 1: (1~5), wherein the amount of the substance of ammonium ion changes because of the type of two kinds of solutes and the amount of substance.It is described mixed
It closes in solution, just with fluorine ion and just, the molar ratio with nitrite ion is 1: (1~5), the wherein substance of ammonium ion
Measure the amount because of the type of two kinds of solutes and substance due to change, more specifically, in the mixed solution, just with fluorine ion, just match nitre
Acid ion and the first molar ratio with ammonium ion are preferably 1: (1~5): (1~6);More preferably 1: (2~3): (2~4),
Most preferably 1: 3: 4;Or in the mixed solution, ammonium ion is just matched with fluorine ion, just with nitrite ion and just
Molar ratio is preferably 1: (1~5): (1~6);More preferably 1: (2~3): (2~4), most preferably 1: 3: 4;The mixing is molten
The mass fraction of solute is preferably 15%~45% in liquid, and more preferably 20%~30%.
In the present invention, there is no particular/special requirement, preparation methods well known in the art in source of the present invention to the silicon wafer of borehole
The silicon wafer of the borehole of preparation, it is conventional, it is prepared in accordance with the following methods often through by the silicon wafer of borehole: will be wait make
Suede silicon wafer successively passes through alkali cleaning, pickling, heavy silver and borehole processing, obtains the silicon wafer of borehole;Wherein, the present invention treats the silicon of making herbs into wool
Piece does not have particular/special requirement, can be black silicon or ordinary silicon chip;Technique of the present invention to pickling, alkali cleaning, heavy silver and borehole processing
Also without particular/special requirement, method well known in the art.
According to the present invention, also by the silicon wafer of reaming, routinely technique carries out subsequent processing to the present invention, obtains the polycrystalline of making herbs into wool
Black silicon wafer;Wherein, the silicon wafer after desilverization reaming is preferably successively passed through alkali cleaning, pickling, washing and drying etc. and obtained by the present invention
The silicon wafer of making herbs into wool, wherein the present invention does not have particular/special requirement to the technique of alkali cleaning or pickling, and well known to a person skilled in the art available
The technique of silicon wafer alkali cleaning and pickling after reaming.
The etching method of the black silicon wafer of polycrystalline provided by the invention, by first by the silicon wafer of borehole be placed in mixed solution into
Row desilverization expanding treatment, obtains the silicon wafer of reaming;Then by the silicon wafer of reaming, routinely technique carries out subsequent processing, obtains making herbs into wool
The black silicon wafer of polycrystalline.Wherein, the present invention passes through the mixed solution for selecting the mixed solution to form for ammonium fluoride and nitric acid, fluorination
Mixed solution, ammonium nitrate and the hydrofluoric acid of the mixed solution of ammonium and nitrate composition, ammonium fluoride and nitrous acid composition form mixed
Close solution, ammonium nilrite and hydrofluoric acid composition mixed solution, ammonium nitrate and ammonium fluoride composition mixed solution, ammonium nilrite and
The solution or ammonium ceric nitrate of ammonium fluoride composition and the solution of ammonium fluoride composition;So that etching method of the invention can be one
Two processing steps of the desilverization and reaming are realized simultaneously in a solution system, and the flannelette of the silicon wafer of obtained making herbs into wool is preferable;Not only
The process flow of reaction is shortened, and reduces the cost of silicon wafer wool making.
Specifically, the process flow chart of the application and the silicon wafer of prior art preparation making herbs into wool is shown in Fig. 5~Fig. 6;Fig. 5 is existing
Flow chart under standard technology;Fig. 6 is the process flow chart of preparation method provided by the invention.
In addition, it is necessary to, it is noted that just match nitrate ion in the application with fluorine ion, just with nitrite ion and just
Molal quantity refer to when configuring mixed solution, the molal quantity of the anion of addition, the molal quantity of nitrite ion, nitrate anion
The molal quantity of ion, as joined 1mol ammonium fluoride in mixed solution, 1mol ammonium nitrate obtains mixed solution, then just with fluorine from
The molal quantity of son is 1mol, and just the molal quantity with nitrate ion is 1mol.
It is clearly and completely described below in conjunction with the technical solution of the embodiment of the present invention, it is clear that described implementation
Example is only a part of the embodiment of the present invention, instead of all the embodiments.Based on the embodiments of the present invention, this field is common
Technical staff's every other embodiment obtained without making creative work belongs to the model that the present invention protects
It encloses.
Embodiment 1
The process for etching of the black silicon of polycrystalline:
Using the black silicon wafer of standard cleaning process polycrystalline, specific process parameter are as follows: solution is received prosperous for 14%KOH+0.5%
Additive A, percentage are volume fraction, 78 DEG C of temperature, reaction time 210s.KOH mass fraction is 48%.
One layer of silver nano-grain is being deposited by the silicon chip surface of cleaning process.Specific process parameter are as follows: solution 1.5%
HF+0.3% receives prosperous additive B, and percentage is volume fraction, and 25 DEG C of temperature, reaction time 120s.HF mass fraction is 49%.
The silicon wafer for having deposited silver nano-grain is subjected to borehole.Specific process parameter are as follows: solution 11.4%HF+32%
H2O2+ 0.5%, which receives prosperous addition of C+0.16%, receives prosperous additive D, and percentage is volume fraction, and 34~36 DEG C of temperature, the reaction time
210s.HF mass fraction is 48%, and hydrogen peroxide mass fraction is 30%.
The silicon wafer of borehole is subjected to desilverization reaming unification processing.Specifically comprises the processes of: the silicon wafer of borehole is placed in solution component
For NH4F+NH4NO3Mixed aqueous solution in, { wherein: NH4F and NH4NO3Molar ratio be 1: 3, Solute mass concentration 30% is (i.e.
NH4F+NH4NO3The sum of two kinds) }, 10 DEG C of reaction temperature, reaction time 100s obtains the silicon wafer of desilverization reaming.
The silicon wafer of desilverization reaming is successively subjected to alkali cleaning (NaOH+NH3·H2O+H2O2, 120s-180s;Room temperature), pickling
(NaOH+NH3H2O+H2O2,120s-180s;Room temperature), washing and drying (nitrogen/clean compressed air;Heating), it is made
The silicon wafer of suede.
The silicon wafer of obtained making herbs into wool is analyzed, the result is shown in Figure 1~Fig. 3, Fig. 1 is the making herbs into wool that embodiment 1 is prepared
The amplification appearance number figure of silicon wafer afterwards, Fig. 2 are the appearance number figure of the silicon wafer after the making herbs into wool that embodiment 1 is prepared, Fig. 3
The scanning electron microscope (SEM) photograph of silicon wafer after the making herbs into wool being prepared for embodiment 1.From three width figures as can be seen that the present invention obtain it is more
Frosted finish effect is macroscopically presented in brilliant black silicon, and microcosmic upper hole is more uniformly fine and close.
Embodiment 2
The preparation of borehole silicon wafer is the same as embodiment 1;
The silicon wafer of borehole is subjected to desilverization reaming unification processing.Specifically comprises the processes of: the silicon wafer of borehole is placed in solution component
For NH4F+NH4NO3Mixed aqueous solution in, { wherein: NH4F and NH4NO3Molar ratio be 1: 3, Solute mass concentration 20% is (i.e.
NH4F+NH4NO3The sum of two kinds) }, 25 DEG C of reaction temperature, reaction time 100s obtains the silicon wafer of desilverization reaming.
It is detected by scanning electron microscope, vesicular texture is presented in the black silicon appearance of polycrystalline, and hole is also uniform and fine and close.
A step reaming can be realized under particular solution by above-mentioned experiment, it is presumed that, reaction mechanism may be: by
Production is hydrolyzed in water into NH in ammonium salt4OH, while solution is in acidity, under acid condition, nitrate anion/nitrite anions and silver nanoparticle
It being reduced after grain contact, a large amount of holes is generated in silver nano-grain, the hole in silver nano-grain is injected into Si by contact,
The Si of contact portion can be oxidized to silica, and silica can be by F-Corrosion generates fluosilicic acid, works as silver nano-grain
In hole injection rate be greater than silica be corroded rate when, silver nano-grain can be complexed by a large amount of ammonium hydroxide, from
And silicon chip surface is left, achieve the effect that the desilverization, when without silver nano-grain as reaction site, nitric acid direct oxidation silicon wafer is raw
At silica, thus by F-Corrosion, achievees the effect that reaming.
Comparative example 1:
The preparation of borehole silicon wafer is the same as embodiment 1;
The silicon wafer of borehole is subjected to desilverization reaming unification processing.Specifically comprises the processes of: the silicon wafer of borehole is placed in solution component
For NH4F+KNO3Mixed aqueous solution in, { wherein: NH4F and NH4NO3Molar ratio be 1: 5, Solute mass concentration 15% is (i.e.
NH4F+NH4NO3The sum of two kinds) }, 10 DEG C of reaction temperature, reaction time 100s obtains the silicon wafer of desilverization reaming.
The reaction is very slow, and detecting to the silicon wafer of obtained borehole, as a result sees Fig. 4,
Fig. 4 is the appearance number figure of the silicon wafer after the making herbs into wool that comparative example 1 is prepared;, it can be seen from the figure that its flannelette
It is not much different with flannelette after borehole, dark and some turn to be yellow, the obvious not formed frosted finish effect of crystal grain.
The above description of the embodiment is only used to help understand the method for the present invention and its core ideas.It should be pointed out that pair
For those skilled in the art, without departing from the principle of the present invention, the present invention can also be carried out
Some improvements and modifications, these improvements and modifications also fall within the scope of protection of the claims of the present invention.