CN102856189A - Method for processing surface of crystal wafer - Google Patents
Method for processing surface of crystal wafer Download PDFInfo
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- CN102856189A CN102856189A CN2012103509334A CN201210350933A CN102856189A CN 102856189 A CN102856189 A CN 102856189A CN 2012103509334 A CN2012103509334 A CN 2012103509334A CN 201210350933 A CN201210350933 A CN 201210350933A CN 102856189 A CN102856189 A CN 102856189A
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Abstract
The invention discloses a woolen making method of a crystal wafer. The woolen making method comprises the steps of: (1) carrying out isotropic etching polishing of chemical solution on the surface of the crystal wafer, reducing the surface roughness of the crystal wafer, (2) carrying out isotropic etching woolen making treatment of the chemical solution on the surface of the crystal wafer, and reducing the surface reflectance of the crystal wafer. The woolen making method is characterized in that the woolen making method is suitable for all types of crystal wafers, and is small in woolen surface, low in production cost and short in woolen making time.
Description
Technical field
The present invention is the processing method about crystal silicon chip surface in producing the solar cell process, particularly relevant technology at crystal silicon chip surface preparation matte.It is wide that process for treating surface of the present invention has applicability, and the matte size is little, and production cost is low, and the advantage such as the making herbs into wool time is short.
Background technology
Along with non-renewable energy resources known on the earth, coal for example, oil etc. constantly reduce, and the development and utilization of regenerative resource more and more is subject to people's attention.The solar battery technology that solar energy is converted to electric energy is one of major technique of present renewable energy utilization.Wherein, crystal silicon solar energy battery is most widely used solar cell in the various solar battery technologies.
Crystal silicon solar energy battery is a kind of device that solar energy directly is converted to electric energy.Compare with the solar cell of other type, crystal silicon solar energy battery has the conversion efficiency height, long service life, the advantage such as maintenance cost is low.Crystal silicon solar energy battery accounts for whole solar cell market more than 80% at present.But even so, the present electric energy that produces of solar cell accounts for the consumption of whole electric energy or insignificant.Its main cause is that solar cell generation current cost is higher than the cost of electricity-generating of traditional non-regeneration energy.Therefore, the cost of electricity-generating of reduction solar cell has very important meaning.
The cost of electricity-generating that reduces solar cell mainly contains two aspects, and the one, the production cost of reduction solar cell, the 2nd, the photoelectric conversion efficiency of raising solar cell.
Reducing the raw-material cost of production solar cell is one of production cost major measure that reduces by solar cell.Because the cost of crystal silicon chip has occupied the production cost of the solar cell more than 50%, therefore, the cost that reduces crystal silicon chip is one of production cost approach that reduces most effectively by solar cell.
The crystal silicon chip that is used at present large-scale production mainly contains two kinds, pulling of crystals silicon chip and casting polycrystalline silicon sheet.Patent CN200510059736.7 and CN200910145225.5 have described respectively the production method of pulling of silicon single crystal and casting polycrystalline silicon.The photoelectric conversion efficiency of the solar cell that the monocrystalline silicon piece that is formed by pulling of silicon single crystal section is prepared is the highest.Although the production cost of casting polycrystalline silicon sheet is lower than the production cost of pulling of crystals silicon chip, the photoelectric conversion efficiency of the solar cell that employing casting polycrystalline silicon sheet is produced is relatively low.
It is the production method of a kind of monocrystalline silicon piece of being caused gradually that recently photovoltaic circle is paid attention to such as the described casting single crystal of patent CN200910099992.7.With respect to pulling of silicon single crystal and casting polycrystalline silicon, casting monocrystalline silicon has crystalline size much larger than pulling of silicon single crystal, and energy consumption is low, is 25% of pulling of silicon single crystal only, and usable area is large, and square is without advantages such as circular arc leftover pieces.
When being caused that gradually photovoltaic circle is paid attention to, some problems of casting single crystal silicon technology also come out gradually.The outward appearance of casting single crystal silicon solar cell and the contradiction between the conversion efficiency are one of them problems.
In the production process of casting monocrystalline silicon, because the impact of various factors, in a silicon ingot casting, some is polysilicon.This is just so that the casting single crystal silicon ingot after being cut into slices, exists monocrystalline silicon region and polysilicon region simultaneously on same casting single crystal silicon chip.
On a slice casting single crystal silicon chip, exist simultaneously the fact of monocrystalline silicon region and polysilicon region to bring difficulty to producing solar cell.If adopt traditional fine-hair maring using monocrystalline silicon slice method that the casting single crystal silicon chip is implemented making herbs into wool, i.e. aqueous slkali etching method, on the casting single crystal silicon chip after the making herbs into wool, monocrystalline silicon region reflectivity between 10 to 11%.And at polysilicon region, reflectivity can be up to more than 20%.In other words, the casting single crystal silicon chip can produce very large reverberation contrast after through aqueous slkali making herbs into wool, had a strong impact on the outward appearance of the solar module of being produced by casting single crystal silicon chip solar cell.
If adopt the etching method of traditional polysilicon chip, namely adopt the method for acid solution making herbs into wool that the casting single crystal silicon chip is implemented making herbs into wool, although the difference of the reflectivity of monocrystalline silicon region and polysilicon region can be greatly improved, but because the raising of the reflectivity of monocrystalline silicon region, the photoelectric conversion rate of the casting single crystal silicon chip solar cell of monolithic also descends thereupon.
Summary of the invention
For above the deficiencies in the prior art, technical scheme of the present invention provides a kind of etching method of new crystal silicon chip.
One of purpose of the present invention is the etching method of seeking a kind of casting single crystal silicon chip, and this etching method has kept the just pyramidal matte of crystal region generation on the casting single crystal silicon chip, is reduced in simultaneously the reflectivity of polysilicon region on the casting single crystal silicon chip.
Another object of the present invention is the technology of a kind of alkaline solution anisotropy making herbs into wool corrosion of exploitation casting polycrystalline silicon, makes casting polycrystalline silicon after implementing the making herbs into wool of alkaline solution anisotropic etch, and the reflectivity after its luminance factor acid solution corrosion is low.
Further purpose of the present invention is, by means of the exploitation of above binomial technology, invents a kind of process for etching, and this process for etching goes for various types of crystal silicon chips, for the large-scale production solar cell is provided convenience and reduced cost.
Last purpose of the present invention is to shorten the preparation needed time of matte in large-scale production solar cell process.
The invention provides a kind of matte preparation method of crystal silicon chip.Etching method of the present invention can be prepared on the surface of crystal silicon chip size less than 2 microns matte.The making herbs into wool condition of the present invention of optimizing can make the matte size of surface of crystalline silicon between 0.5 to 1.5 micron.
The present invention finds that monocrystalline silicon piece and the polysilicon chip reflectivity difference after implementing the making herbs into wool of alkaline chemical solution anisotropic etch can weaken along with reducing of matte size.Therefore, the invention discloses a kind of etching method, the method can be prepared on the surface of crystal silicon chip the matte size less than 2 microns little matte.Owing to there are various crystal orientation, after implementing the making herbs into wool of alkaline solution anisotropic etch, polysilicon surface generates the non-positive pyramid that differs in the angle of inclination.These non-just pyramidal reflectivity increase along with the increase at angle of inclination.Along with reducing of these non-just pyramidal sizes, the reflection differences that cause at the angle of inclination also weakens thereupon, and what namely the difference of reflectivity became between each crystal orientation is no longer so obvious.
The invention discloses a kind of etching method, the method at first adopts the method for chemical corrosion the crystal silicon chip surface finish, in other words, reduces the surface roughness of crystal silicon chip, and then making herbs into wool is implemented on the crystal silicon chip surface after polishing.
One of advantage of the present invention is that etching method of the present invention is applicable to all types of crystal silicon chips.For example, the present invention both had been applicable to the pulling of crystals silicon chip, also was applicable to casting single crystal silicon chip and casting polycrystalline silicon sheet.Wherein, in the casting single crystal silicon chip, the area of polysilicon accounts for the area 1% to 99% of whole casting single crystal silicon chip.Simultaneously, the present invention is applicable to various doped crystal silicon chips, for example N-type crystal silicon chip and P type crystal silicon chip.
One of purpose of chemical solution etch polishing crystal silicon chip of the present invention is to shorten the making herbs into wool time.The shortening making herbs into wool time is in one of key technology of the matte of crystal silicon chip Surface Creation below 2 microns.The lip-deep matte size of crystal silicon chip is less, because the reflectivity missionary society that cause in the various crystal orientation of polysilicon is weakened.
Another purpose of chemical solution etch polishing crystal silicon chip of the present invention is to reduce the reflectivity of surface of crystalline silicon.A large amount of industrial practices prove that the surface of crystalline silicon reflectivity after the making herbs into wool increases along with reducing of matte size.This phenomenon becomes more obvious after the matte size is less than 3 microns.The main cause that produces this phenomenon is the out-of-flatness on crystal silicon chip surface, thereby causes vertical incidence light not produce secondary reflection at all mattes.After adopting the bright chemical solution etch polishing crystal silicon chip surface of this law, the out-of-flatness of surface of crystalline silicon has obtained effectively solving.Therefore, making herbs into wool technology of the present invention can reduce the reflectivity on crystal silicon chip surface effectively.
Making herbs into wool step of the present invention is to implement after the crystal silicon chip surface is by the chemical solution etch polishing.Because the crystal silicon chip surface has good planarization, under the prerequisite that does not affect reflectivity, can reduce arbitrarily the size of matte.The present invention confirms, after the matte size on crystal silicon chip surface reduces gradually, in non-positive pyramid matte, because the reflection differences that the angle of inclination difference causes also weakens thereupon.Equally, the difference of the reflectivity between positive pyramid and the non-positive pyramid also weakens gradually, and in other words, the difference between them can be left in the basket.Therefore, the casting single crystal silicon chip at the positive pyramid that its monocrystalline silicon region generates, has kept the advantage of alkaline solution monocrystalline making herbs into wool after adopting etching method making herbs into wool of the present invention.Polysilicon region on the casting single crystal silicon chip after adopting etching method of the present invention, generates the different non-positive pyramid in angle of inclination.Because these non-just pyramidal sizes are very little, reflectivity is low, they with just between the pyramid reflection differences can be left in the basket.
Further advantage of the present invention is, the chemical solution anisotropic etch making herbs into wool time of the present invention, compare with the making herbs into wool time of traditional monocrystalline silicon piece, and can be shortened significantly.Etching method of the present invention can crystal silicon chip making herbs into wool time shorten to 15 minute in.Chemical solution etch polishing step of the present invention is not subjected to the different restriction of corrosion rate in each crystal orientation.If the present invention uses the alkaline solution polishing, the concentration of alkaline solution and polish temperature can at random be enhanced.In fact, alkaline solution etch polishing step of the present invention has utilized the alkaline solution corrosion just under the condition of high concentration and high temperature, and basic identical this feature of the corrosion rate in each crystal orientation realizes alkaline solution etch polishing process.The alkaline solution polishing time that the present invention optimizes is between 2 to 10 minutes.
Another advantage of the present invention is that polishing step of the present invention can corrode to realize with acid solution.With acid solution etch polishing crystal silicon chip etch polishing is reacted at normal temperatures, and polishing etch reaction just can finish within 1 to 2 minute, greatly shorten the whole making herbs into wool time of crystal silicon chip silicon.
Etch polishing step of the present invention provides the necessary condition that generates the small size matte on the crystal silicon chip surface.Crystal silicon chip is after by the chemical solution etch polishing, and the damage layer that is not only produced by the cutting silicon wafer process is corroded totally, and main is to have reduced the surface roughness of crystal silicon chip.Therefore, the crystal silicon chip after this polishing is when being implemented making herbs into wool, and whole surface begins to generate simultaneously matte equably.In other words, implemented the making herbs into wool step by the crystal silicon chip behind the chemical solution etch polishing, anisotropic corrosion reaction begins simultaneously on whole crystal silicon chip surface.
Anisotropic etch of the present invention reaction is in the characteristic that whole surface of crystalline silicon begins simultaneously equably, guaranteed that the present invention can generate the little and uniform pyramid matte of size.Further, because effectively matte begins to generate simultaneously, and the matte size is little, so the making herbs into wool time can significantly be shortened.Under general condition, making herbs into wool step of the present invention only needs about 5 minutes.
A significant advantage of the present invention is that making herbs into wool technology of the present invention is applicable to the crystal silicon chip of any type.Obviously, chemical solution etch polishing step of the present invention is applicable to the crystal silicon chip of any type.No matter be the pulling of crystals silicon chip, the casting polycrystalline silicon sheet, casting single crystal silicon chip, even band silicon silicon chip, after having passed through chemical solution etch polishing step of the present invention, these crystal silicon chip surfaces are all with polished.In other words, any crystal silicon chip is after being implemented chemical solution etch polishing step of the present invention, and their surface characteristics is identical.
Through after the chemical solution etch polishing step of the present invention, when implementing making herbs into wool step of the present invention, undersized matte generates simultaneously on the crystal silicon chip surface.For various crystal silicon chip, according to they crystal orientation features separately, the non-positive pyramid that after process making herbs into wool step, generates positive pyramid or have different inclination angle.Because these pyramidal sizes are all very little, therefore, the different gap of the reflectivity that is caused by the angle of inclination difference can be dwindled greatly.Be that crystalline silicon etching method of the present invention goes for any crystal silicon chip.
The present invention further finds, the pyramidal reflectivity of the differing tilt angles that has been weakened poor can continue to reduce after solar cell is by lamination, in other words, can ignore.The main cause of this phenomenon be the reverberation that on the pyramid that tilts, produces of a part under the effect on upper glass surface, produced total reflection effect.For the casting single crystal silicon chip, to process through etching method of the present invention, the positive pyramid of monocrystalline silicon region is different from the reflectivity between the non-positive pyramid of polysilicon region, after being laminated into solar module, can ignore.
Description of drawings
Fig. 1 has showed through after the chemical solution etch polishing step of the present invention, the reflectivity of monocrystalline silicon region and the reflectivity of polysilicon region.
Fig. 2 showed through after the chemical solution of the present invention corrosion making herbs into wool step, the positive pyramid that generates at monocrystalline silicon region.
Fig. 3 shows through after the chemical solution of the present invention corrosion making herbs into wool step, the non-positive pyramid that generates at polysilicon region.
Fig. 4 displaying is known clearly through after the chemical solution corrosion making herbs into wool step of the present invention, the reflectivity of monocrystalline silicon region and the reflectivity of polysilicon region.
Embodiment
In the following description, for task of explanation, having set forth many details, in order to complete understanding of the present invention is provided, but is not to limit the present invention.
Preparing in the method for matte in the present invention, at first is that crystal silicon chip is implemented chemical solution isotropic etch polishing step, reduces its surface roughness.In other words, be the method that adopts the chemical solution corrosion, reduce the surface roughness of crystal silicon chip.
The step of reduction crystal silicon chip surface roughness of the present invention is a cleaning of finishing successively crystal silicon chip surface organic or inorganic pollutant, the cleaning of crystal silicon chip surface damage layer, and the corrosion process that reduces at last the crystal silicon chip surface roughness.The surface roughness of crystal silicon chip is lower, and its surface is just more smooth, namely surface of crystalline silicon is polished.Therefore, the corrosion step of reduction crystal silicon chip surface roughness of the present invention can be described to chemical solution etch polishing step.The surface roughness of crystal silicon chip is lower, and its reflectivity to incident light is just higher.Therefore, the corrosion step of reduction crystal silicon chip surface roughness of the present invention also can be described to improve the step of crystal silicon chip surface reflectivity.
The crystal silicon chip surface is in operated process, and is for example packaged and when removing stage makeup and costume, inevitably can be by various organic substances and inorganic pollution.These pollutants are present in the outermost layer of crystal silicon chip.So these pollutants at first are corroded in the corrosion process of reduction silicon chip surface roughness of the present invention, in other words, at first are cleaned.
In the process of preparation crystal silicon chip, the crystal on crystal silicon chip surface is subject to damage in various degree.The crystal silicon chip surface that is damaged is referred to as the crystal silicon chip surface damage layer.This surface damage layer in fact is the crystalline silicon with various defectives.In the chemical corrosion process, the crystal silicon chip speed that is corroded depends on the crystal mass of crystalline silicon.In other words, the defective damage layer of tool, such as fine fisssure and dislocation etc., the speed that is corroded is greater than the crystalline silicon with perfect lattice.Therefore, in the corrosion process of reduction crystal silicon chip surface roughness of the present invention, after above-described pollutant was cleaned, the damage layer on crystal silicon chip surface was cleaned thereupon.
After the damage layer on crystal silicon chip surface was cleaned, the roughness on crystal silicon chip surface was still quite high.These roughness mainly are because in the process of preparation crystal silicon chip, the violent friction between line of cut and silicon-carbide particle and the crystal silicon chip causes.The corrosion process of reduction silicon chip surface roughness of the present invention continues the crystal silicon chip corrosion, to realize reducing the purpose of silicon chip surface roughness after having finished crystal silicon chip surface clean and the cleaning of surface of crystalline silicon damage layer.In fact, the present invention has utilized chemical corrosion solution in the poor purpose that realizes reducing the silicon chip surface roughness of the solubility on rugged crystal silicon chip surface.Be subject to the impact of the mass transfer rate of chemical corrosion solution, be greater than it in the concentration on sunk part surface in the concentration of the chemical corrosion solution of surface of crystalline silicon projection.Therefore, the corrosion rate of the projection of surface of crystalline silicon is faster than its corrosion rate at sunk part, makes crystal silicon chip after process is further corroded, and the crystal silicon chip surface roughness is gradually reduced.
Chemical solution corrosion process of the present invention can be used alkaline solution.The broad liquid of so-called alkalescence refers to that the concentration of hydroxide ion is greater than the aqueous solution of hydrogen ion concentration.The alkaline solution of optimization of the present invention can be inorganic alkali solution, for example sodium hydroxide solution and potassium hydroxide solution.Also can be organic base solution, for example aqueous solution of tetramethyl aqua ammonia.In some cases, alkaline solution can also be the mixture of various alkaline solutions, for example, and the mixed-alkali solution of NaOH and tetramethyl aqua ammonia.
The alkaline solution etching condition of the present invention of optimizing is that this condition can reduce the difference of each crystal orientation corrosion rate between its each crystal orientation when being corroded of crystal silicon chip substantially, thereby reaches the purpose that reduces the surface of crystalline silicon roughness.
In order effectively to reduce the surface roughness of crystalline silicon, in alkaline solution corrosion process of the present invention, the concentration of alkaline solution can be between 1% to 40% weight concentration.The concentration of the alkaline solution that the present invention optimizes is between 5% to 20%.Alkaline solution corrosion temperature of the present invention can be between 40 to 100 degree.The corrosion temperature of optimizing can be between 60 to 85 degree.The alkaline solution etching time can be between 1 minute to 30 minutes, and the alkaline solution etching time of optimization can be between 2 minutes to 10 minutes.
For the surface roughness of more effective reduction crystalline silicon, improve the planarization of surface of crystalline silicon, in the step example of some other alkaline solution corrosion crystal silicon chip of the present invention, can add one or more additives.This additive can help to weaken the different feature of each crystal orientation corrosion rate of crystal silicon chip, makes each crystal orientation of crystal silicon chip under the effect of additive, and the speed that is corroded reaches unanimity, thereby obtains smooth crystal silicon chip surface.In other words, generate the crystal silicon chip surface of low surface roughness.
The step of reduction crystal silicon chip surface roughness of the present invention also can adopt acid solution to implement.Acid solution of the present invention refers to that the concentration of hydroxide ion is less than the aqueous solution of hydrogen ion concentration.Acid solution of the present invention is that hydrofluoric acid has the acid of oxidation characteristic with other, perhaps the mixture of salt.For example, the mixture of hydrofluoric acid and nitric acid.The acid that what is called has oxidation characteristic can be nitric acid, sulfuric acid etc.Acid solution of the present invention also can adopt hydrofluoric acid and other to have the salt mixture of oxidation characteristic.For example, the mixture of hydrofluoric acid and potassium permanganate or chromic acid.
In the chemical corrosion process that reduces surface roughness, the concentration of hydrofluoric acid can be controlled between 3% to 40%.The hydrofluoric acid concentration of optimizing is between 5% to 30%.Having the acid of oxidation characteristic and the concentration of salt generally can be controlled between 20% to 50%.
Adopting the acid solution chemical corrosion to reduce in the step of crystal silicon chip surface roughness, corrosion temperature generally can be controlled at 0 to 40 degree.The corrosion temperature of optimizing can be controlled at 3 to 30 degree.Etching time is generally between 1 to 20 minute.The etching time of optimizing is between 2 to 10 minutes.
For the surface roughness of more effective reduction crystalline silicon, improve the planarization of surface of crystalline silicon, in the step example of some other acid solution corrosion crystal silicon chip of the present invention, can add one or more additives.This additive can increase acid solution in the oxidation rate of surface of crystalline silicon, thereby obtains more smooth crystal silicon chip surface.In other words, generate the more crystal silicon chip surface of low surface roughness.
Reduction crystal silicon chip surface roughness step of the present invention is to guarantee to dwindle between monocrystalline silicon region and the polysilicon region in other significant process of making herbs into wool process back reflection rate variance.The surface roughness of crystalline silicon plays a significant role in making herbs into wool process of the present invention.The surface roughness of crystal silicon chip is less, the undersized matte of easier generation just in the making herbs into wool process.The more important thing is that the surface roughness of crystal silicon chip is less, it is even that the matte after the making herbs into wool process more is tending towards.The matte size is little and evenly be the one of the main reasons of dwindling the difference of reflectivity between monocrystalline silicon piece and the polysilicon chip.In other words, the step of reduction surface roughness of the present invention is to be preparation small size, the necessary preparation that the matte of good uniformity is done.
Through after the chemical solution etch polishing step of the present invention, the roughness of surface of crystalline silicon is less than 1 micron.The crystal silicon chip surface roughness of optimizing is through after the chemical solution etch polishing step of the present invention, below 0.8 micron.
Through after the chemical solution etch polishing step of the present invention, owing to the crystal silicon chip surface roughness is lowered, so the average reflectance on crystal silicon chip surface is more than 25%.After Fig. 1 has showed the chemical solution etch polishing step of optimizing through the present invention, at the reflectivity of polysilicon region and monocrystalline silicon region.
Through after the chemical solution etch polishing step of the present invention, on the casting single crystal silicon chip of a slice monocrystalline silicon region and polysilicon region coexistence, no matter at monocrystalline silicon region, or at polysilicon region, its surface roughness is basically identical.That is to say that after process chemical solution etch polishing step of the present invention, the monocrystalline silicon region on the casting single crystal silicon chip and the surface characteristics of polysilicon region are basically identical.
By above detailed description to chemical solution etch polishing step of the present invention, can apparently find, because through after the chemical solution etch polishing step of the present invention, different although monocrystalline silicon piece and polysilicon chip exist the crystal orientation, the surface roughness between them is consistent.Therefore, chemical solution etch polishing step of the present invention is applicable to any type of crystal silicon chip and the prepared crystal silicon chip of any type of slice process.In other words, the silicon chip that any type of crystal silicon chip and any type of slice process generate, after process chemical solution etch polishing step of the present invention, its surface topography and surface characteristics are basically identical.
After process chemical solution etch polishing step of the present invention, because the surface characteristics of whole crystal silicon chip is consistent, be conducive in follow-up making herbs into wool process, the generation size is little, and uniform matte is conducive to dwindle because the monocrystalline silicon piece that the difference of reflectivity causes and the difference between the polysilicon chip.
Through the crystal silicon chip after the chemical solution etch polishing step of the present invention, can directly be implemented second step of the present invention, the making herbs into wool step.Before implementing making herbs into wool step of the present invention, also can implement washed with de-ionized water to crystal silicon chip.The advantage of enforcement washed with de-ionized water is before the making herbs into wool step, can guarantee all crystals silicon chip before being implemented the making herbs into wool step, and its surface state is consistent, avoid the cross pollution between the reactive tank, and crystal silicon chip is exposed in the chemical solution excessively for a long time.
Making herbs into wool step of the present invention be one with alkaline solution anisotropic etch making herbs into wool process.So-called alkaline solution refers to that the concentration of hydroxide ion is greater than the aqueous solution of hydrogen ion concentration.For example, sodium hydrate aqueous solution, potassium hydroxide aqueous solution, and the tetramethyl aqua ammonia aqueous solution, the perhaps mixture between them.
The alkaline solution making herbs into wool condition of the present invention of optimizing is, this making herbs into wool condition can improve each crystal orientation of crystal silicon chip substantially when being corroded, the difference of the corrosion rate between its each crystal orientation, thus generate rapidly small size and uniform matte.
In making herbs into wool step of the present invention, the mass concentration of alkaline solution can be controlled between 0.5% to 5%.The alkaline solution concentration of optimizing can be controlled between 1% to 3%.
In making herbs into wool step of the present invention, the making herbs into wool temperature control is between 60 to 100 degree.Optimize alkali making herbs into wool temperature control at 70 degree between 90 degree.
In making herbs into wool step of the present invention, the making herbs into wool time can be controlled between 3 minutes 20 minutes.Optimize the alkali making herbs into wool time between 4 minutes to 15 minutes.
In making herbs into wool step of the present invention, in order to reach better making herbs into wool effect, a kind of making herbs into wool additive need to be added at least in alkaline solution of the present invention, for example, add the aqueous slkali and isopropyl alcohol of polyethylene glycol in making herbs into wool process of the present invention after, the matte that generates can be less and more even.
One of significant advantage of the present invention is, because before the making herbs into wool step, the surface of crystal silicon chip is polished, therefore can there be than the making herbs into wool time of traditional etching method significantly shortening the required time of making herbs into wool step of the present invention.The making herbs into wool time of the present invention can be than the making herbs into wool time shorten about 1/4th of traditional etching method.Because the making herbs into wool step time of the present invention significantly is shorter than the making herbs into wool time of adopting conventional method, even therefore add the time of chemical solution etch polishing step of the present invention, the etching method wastage in bulk or weight time of the present invention is than adopting traditional etching method obviously to shorten.The needed total time of etching method that the present invention optimizes is generally between 5 to 15 minutes.
Another significant advantage of the present invention is, etching method of the present invention can be prepared average-size less than 2 microns even matte.Because making herbs into wool step of the present invention implements, therefore the making herbs into wool time can be shortened greatly, for the matte size that reduces after the making herbs into wool provides good condition behind polishing step.The matte size that the present invention optimizes is at 0.5 to 2 micron.
Fig. 2 has showed the matte kenel of monocrystalline silicon region in the casting single crystal silicon chip.
Fig. 3 has showed the matte kenel of polysilicon region in the casting single crystal silicon chip.
As can be seen from Figure 2, after process making herbs into wool step of the present invention, monocrystalline silicon region generates the positive pyramid that is of a size of less than 2 microns.After sunlight impinges perpendicularly on these positive pyramids, produce 2 secondary reflections.The reflectivity of monocrystalline silicon region can be reduced to about 10%.
And at polysilicon region, owing to have various crystal orientation, and the feature different according to each crystal orientation corrosion rate, as shown in Figure 3, what generate in the polycrystalline zone is the non-positive pyramid with differing tilt angles.Along with the increase at angle of inclination, the condition of 2 secondary reflections is weakened gradually, and Here it is why in the high main cause of polysilicon region reflectivity.
Fig. 4 is the casting single crystal silicon chip through after the making herbs into wool step of the present invention, the comparison of the reflectivity of its monocrystalline silicon region and the reflectivity of polysilicon region.The reflectivity of monocrystalline silicon region with adopt traditional process for etching after reflectivity suitable, the minimum point of reflectivity is about 10%.And at the reflectivity of polysilicon region, after having adopted etching method of the present invention, be in close proximity to the reflectivity of monocrystalline silicon region.In other words, adopted etching method of the present invention after, the reflectivity of monocrystalline silicon region and the reflectivity of polysilicon region approach, and have reduced the aberration between monocrystalline silicon region and the polysilicon region.
When the casting single crystal silicon chip that has simultaneously monocrystalline silicon region and polysilicon region, adopt prepared one-tenth solar cell behind the etching method of the present invention, the aberration between its monocrystalline silicon region and the polysilicon region can further be weakened after by lamination.Owing to generate non-positive pyramid at polysilicon region, sunlight on the pyramid that tilts the catoptrical angle of reflection that produces can be greater than critical angle, so total reflection can occur on surface on glass in the reverberation on the pyramid of these inclinations, has further reduced because the reflection differences that pyramidal angle of inclination difference causes.Therefore, adopt the prepared solar cell of etching method of the present invention after by lamination, the difference of the reflectivity in crystal region and polycrystalline zone is further dwindled.In other words, casting single crystal silicon chip prepared solar cell after adopting etching method of the present invention can not produce obvious reflectivity difference after by lamination.
Embodiment 1
Dispose the tetramethyl Dilute Ammonia Solution of 20% percentage by weight as etch polishing solution, it is stand-by that etch polishing solution is heated to 90 degree.Dispose the sodium hydroxide solution of 1.5% percentage by weight as corrosion making herbs into wool solution, making herbs into wool is heated to the rear an amount of isopropyl alcohol of adding of 78 degree and the making herbs into wool additive is stand-by corroding.The casting single crystal silicon chip that contains 30% polysilicon region is put into etch polishing solution.After 5 minutes this casting single crystal silicon chip is being taken out from etch polishing solution, then putting into corrosion making herbs into wool solution.Making herbs into wool is taken out after 7 minutes and is cleaned with deionized water.The average reflectance that records at monocrystalline silicon region is 9.9%, and the average reflectance of polysilicon region is 18%.This casting single crystal silicon chip is prepared to solar cell, and the photoelectric conversion efficiency that records this solar cell is 18.2%, wherein, open circuit voltage, short circuit current and quality factor are respectively 631 millivolts, 36.5 milliamperes/square centimeter and 78.9%.
Embodiment 2
Embodiment 3
Dispose the sodium hydroxide solution of 5% percentage by weight as etch polishing solution, it is stand-by that etch polishing solution is heated to 85 degree.Configuration 2% tetramethyl Dilute Ammonia Solution is as corrosion making herbs into wool solution, and it is stand-by that corrosion making herbs into wool is heated to behind 80 degree an amount of isopropyl alcohol of adding and making herbs into wool additive.Monocrystalline silicon piece is put into etch polishing solution.This monocrystalline silicon piece took out from etch polishing solution after 3 minutes, directly put into corrosion making herbs into wool solution.Making herbs into wool is taken out after 5 minutes and is cleaned with deionized water.The average reflectance that records this monocrystalline silicon piece is 10.1%.This monocrystalline silicon piece is prepared to solar cell, and the photoelectric conversion efficiency that records this solar cell is 18.4%, wherein, open circuit voltage, short circuit current and quality factor are respectively 633 millivolts, 36.8 milliamperes/square centimeter and 79.1%.
Claims (15)
1. the preparation method of a crystal silicon chip surface matte is characterized in that, the preparation method of this crystal silicon chip surface matte may further comprise the steps:
(1) the chemical solution etch polishing is implemented on the crystal silicon chip surface, reduced the surface roughness of crystal silicon chip;
(2) chemical solution corrosion making herbs into wool is implemented on the crystal silicon chip surface, reduced the surface reflectivity of crystal silicon chip.
2. crystal silicon chip according to claim 1 is characterized in that, described crystal silicon chip is the casting single crystal silicon chip, casting polycrystalline silicon sheet, pulling of crystals silicon chip.
3. casting single crystal silicon chip according to claim 2 is characterized in that, on described casting single crystal silicon chip, the area of polysilicon accounts for the area 1% to 99% of whole casting single crystal silicon chip.
4. crystal silicon chip according to claim 1 is characterized in that, described crystal silicon chip is the N-type crystal silicon chip, or P type crystal silicon chip.
5. chemical solution etch polishing step according to claim 1 is characterized in that described chemical solution is alkaline chemical solution, or acidic chemical solution.
6. chemical solution etch polishing step according to claim 5 is characterized in that, in described chemical solution etch polishing step, can add one or more additives.
7. chemical solution etch polishing step according to claim 1 is characterized in that, the optimization etching time of described chemical solution etch polishing step is between 0.5 minute to 10 minutes.
8. the surface roughness of reduction crystal silicon chip according to claim 1 is characterized in that, crystal silicon chip is after described chemical solution etch polishing step, and the average reflectance of crystal silicon chip is greater than 25%.
9. the surface roughness of reduction crystal silicon chip according to claim 8 is characterized in that, crystal silicon chip is after described chemical solution etch polishing step, and the average reflectance of the crystal silicon chip of optimization is greater than 28%.
10. chemical solution corrosion making herbs into wool step according to claim 1 is characterized in that corrosion making herbs into wool step is to adopt alkaline chemical solution to realize corroding making herbs into wool.
11. alkaline chemical solution corrosion making herbs into wool step according to claim 10 is characterized in that, in described alkaline chemical solution corrosion making herbs into wool step, adds at least a kind of making herbs into wool additive in this alkaline chemical solution.
12. alkaline chemical solution corrosion making herbs into wool step according to claim 10 is characterized in that, optimizes the making herbs into wool step time between 3 minutes to 15 minutes.
13. the preparation method of a kind of crystal silicon chip according to claim 1 surface matte is characterized in that, it is 0.5 to 2 micron matte that described preparation method prepares average-size at surface of crystalline silicon.
14. the preparation method of a kind of crystal silicon chip according to claim 1 surface matte is characterized in that described preparation method's time is 5 minutes to 15 minutes.
15. the preparation method of a kind of crystal silicon chip according to claim 14 surface matte is characterized in that described preparation method's the optimization time is 6 minutes to 10 minutes.
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| CN109427930A (en) * | 2017-09-04 | 2019-03-05 | 苏州易益新能源科技有限公司 | A method of flannelette is selectively prepared on crystal silicon chip surface |
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