CN101312222A - Method of manufacturing solar cell - Google Patents
Method of manufacturing solar cell Download PDFInfo
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- CN101312222A CN101312222A CNA200710104807XA CN200710104807A CN101312222A CN 101312222 A CN101312222 A CN 101312222A CN A200710104807X A CNA200710104807X A CN A200710104807XA CN 200710104807 A CN200710104807 A CN 200710104807A CN 101312222 A CN101312222 A CN 101312222A
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- solar cell
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
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Abstract
Disclosed is a process for preparing solar cells, which comprises that first, preparing a substrate, then, injecting ions into the substrate to form a p-n doped structure by the ion implantation technique, next, forming a buffer layer on the substrate and forming recessed patterns in the buffer layer, and then, forming a metal layer on the buffer layer and filling with the recessed patterns.
Description
Technical field
The present invention is relevant for the manufacture method of a kind of solar cell (Solar Cell), particularly relevant for a kind of by form resilient coating in the silicon wafer back side, reducing the structural stress that is produced based on the slimming solar cell, and then the manufacture method of the solar cell of the buckling phenomenon that improves base plate stress effectively and caused.
Background technology
Recently the shortage of world energy sources causes the continuous hurricane of oil price to rise, the exploitation that each country of the whole world there's no one who doesn't or isn't drops into energy-conserving product energetically, and for example solar cell (Solar cell) is the product under this trend.Under oil and environmental protection (Global Greenhouse Effect) problem, make global solar cell sales volume become the growth of several times.Solar cell is a kind of photoelectrical semiconductor component that utilizes transform light energy for electric energy, its change the mechanism for: solar radiation is shone on solar cell, make electronics and hole move to p-doped region (p-doped region) and n-doped region respectively, and cause two interregional generation voltage difference and electric currents.Because conversion efficiency is quick, therefore need only irradiates light on assembly, moment just can output voltage and electric current.In addition, in the changing the mechanism of solar cell, its conversion efficiency depends on inner electronics, hole rate travel and the outside light area of getting, and wherein Nei Bu electronics, hole rate travel mainly are to be controlled by the composition material of solar cell.In other words, the conversion efficiency of solar cell mainly is that structure and the quality by p-doped region and n-doped region decides, and when wherein defectiveness existed, the conversion efficiency of solar cell will reduce significantly.
The most frequently used solar cell raw material is representative with silicon (silicon) at present, and according to the difference of structure, above-mentioned silicon raw material comprises single crystal silicon (Single-crystal), polycrystal silicon (Poly-crystal) and amorphous silicon (Amorphous), and formed solar cell is referred to as single crystal silicon solar cell, polycrystal silicon solar cell and amorphous silicon solar cell respectively.Wherein the conversion efficiency of single crystal silicon is the highest, and the cutting of polycrystal silicon is more difficult, and the amorphous silicon low price, need not encapsulation and form the fastest.In addition, the conversion efficiency of amorphous silicon is too low, life of product is too short, and therefore, solar cell is made raw material most based on single crystal silicon and polycrystal silicon.
The development priority of solar photoelectric industry is how to save material and improves conversion efficiency at present.Because silicon wafer costs an arm and a leg, and present global solar cell has 90% to be as its substrate by the silicon wafer raw material.In addition, the solar panel back side all attaches a sheet metal, to transfer the connecting circuit of electric energy process to as solar energy.Because sheet metal causes the loss of electric energy, this circuit to make solar cell actual power step-down.Therefore, in order to improve collection power, must reduce the contact area between solar panels and the conductive metal sheet.A kind of feasible pattern, makes conductive contact surfaces amass and diminishes again in the perforation of the position of needs energising for add insulation board between above-mentioned two-ply.For example, Germany Fraunhofer ISE research institute, produce conversion efficiency and reached 20.2% silicon wafer solar cell, it is to adopt laser sintered contact (Laser FiredContacts:LFC) technology to reduce contact area, its step is greatly slightly: evaporation aluminium lamination and insulating barrier (passivation layer) on the back of the body surface of solar cell, utilize laser to punch aluminium lamination to form conductive junction point then.Laser sintering processes can solve the problem that original electric energy runs off effectively, and utilize laser sintered contact technology, do not need to utilize tradition expensive little shadow, etching technique in the insulating barrier at the silicon crystal slate back side, to form hole (holes) pattern, to hold aluminium matter electrode.Therefore, laser sintered contact technology cost low, save material and speed fast.The per unit solar panels only need the time in an about second, and are applicable to the silicon crystal slate of each thickness, therefore, are fit to very much industrial mass-produced technology.
Utilize laser sintered contact technology, can produce the solar cell of high conversion efficiency at silicon.High efficiency solar cell can be applied to space industry.Yet the solar cell of ultra-thin silicon chip manufacturing because thickness is too thin, therefore occurs being subjected to external force and the phenomenon that produces the chip bending, as a result the structure of remote-effects whole solar cell, conversion efficiency and reliability easily.
Therefore, based on above-mentioned problem, and the demand of making solar cell in response to silicon as thin as a wafer, the conversion efficiency of improving solar cell from the manufacture process technology has become important developing direction, so the present invention will propose a kind of solar battery structure with high conversion efficiency and manufacture method thereof that prevents silicon bending as thin as a wafer.
Summary of the invention
The object of the present invention is to provide the solar cell of a kind of high conversion efficiency, slimming.
A further object of the present invention is to provide a kind of solar battery structure with high conversion efficiency and manufacture method thereof that prevents silicon bending as thin as a wafer.
Another purpose of the present invention is to provide a kind of can simplify the solar cell of technology to be applicable to that the large tracts of land assembly is made.
The invention provides a kind of manufacture method of solar cell, comprising: at first, purchase substrate, for example wafer; Afterwards, in substrate, inject ion to form the p-n doped structure with ion implantation technique; Subsequently, form resilient coating, among resilient coating, form groove pattern again in substrate back; Then, carry out the groove etching cleaning; Afterwards, on resilient coating, form metal level, and fill up groove pattern.
Above-mentioned groove pattern is to finish by the laser groove cutting process.In one embodiment, wherein the width of groove pattern is that 25-40 nanometer, the degree of depth are that 30-50 nanometer and spacing are 320 to 400 nanometers.Wherein above-mentioned metal level can be finished by the two-stage, phase I is to utilize the thin the first metal layer of method formation of evaporation, sputter or hot-dip to fill up groove pattern, and second stage is to utilize the method for wire mark to form the second thicker metal level on the first metal layer.Wherein the thickness of the first metal layer is the 1.5-3.0 micron, and second metal layer thickness is the 25-40 micron.
The manufacture method of solar cell of the present invention also can further be included in the formation groove pattern and carry out the groove etching cleaning afterwards.After forming metal level, on metal level, form anti-reflecting layer, after forming anti-reflecting layer, carry out sintering process at last.
The manufacture method of solar cell of the present invention by forming resilient coating in the silicon wafer back side, can reduce the structural stress that is produced based on the slimming solar cell, and then the buckling phenomenon that improves base plate stress effectively and caused.
Description of drawings
By following detailed description also in conjunction with the accompanying drawings, can understand foregoing and plurality of advantages of the present invention easily, wherein:
Fig. 1 is the schematic cross-section that forms the p-n doped structure according to of the present invention among silicon wafer.
Fig. 2 is the schematic cross-section that deposits resilient coating according to of the present invention on silicon wafer.
Fig. 3 is the schematic cross-section that forms a plurality of groove patterns according to of the present invention among resilient coating.
Fig. 4 is the schematic cross-section that deposits the first metal layer according to of the present invention on above-mentioned resilient coating and wafer.
Fig. 5 is the schematic cross-section that deposits second metal level according to of the present invention on the first metal layer.
Fig. 6 is the schematic cross-section that forms anti-reflecting layer according to of the present invention on second metal level.
Main symbol description among the figure:
100 silicon wafer 101n-doped region 102p-doped regions, 103 resilient coatings
104 grooves (groove pattern), 105 the first metal layers, 106 second metal levels, 107 anti-reflecting layers
Embodiment
Some embodiments of the present invention are described in detail as follows.Yet except the embodiment that describes in detail, the present invention can extensively implement in other embodiments, and opinion scope of the present invention is not limited to following embodiment.Moreover for clearer description being provided and being more readily understood the present invention, each several part is not drawn according to its relative size in the accompanying drawing, and incoherent detail section is not drawn fully yet, succinct in the hope of accompanying drawing.
Please refer to accompanying drawing, wherein shown only is for the preferred embodiments of the present invention are described, is not in order to restriction the present invention.In miniaturization as thin as a wafer in the solar battery structure of silicon, in order not make the deformation of ultra-thin silicon chip, the present invention develops discovery after deliberation can use the change structural stress in silicon back side formation special substance resilient coating, strengthen whole solar battery structure, improve the ability of anti-strain of solar battery structure or stress.And the present invention can further utilize and form an anti-reflecting layer in the silicon wafer back side, and this anti-reflecting layer is able to effectively reflect unabsorbed light, to increase internal conversion efficient.
For example, the main constituent of above-mentioned cushioning layer material layer comprises silicon dioxide, silicon nitride or silicon oxynitride.
In one embodiment, by the absorbing light surface that changes baseplate material (for example: cadmium telluride, GaAs, Gallium indium arsenide etc.) and utilize non-flattening to increase effective extinction surface area, to increase the conversion efficiency of solar cell, this is also contained by notion of the present invention.
Solar cell manufacturing of the present invention comprises the steps.At first, prepare a substrate, for example wafer.For example, wafer is that [100] crystallization direction, resistivity are the p-type base silicon wafer 100 of 1.2 ohm-centimeter (ohm cm).The size of wafer 100 can be selected according to practical application, for example is the silicon wafer of diameter 150mm, leading edge 127mm.And the thickness of silicon wafer 100 for example is 80-180 micron (micro-meter).
Then, silicon wafer 100 passes through a non-grade to etching, this is photoetching (photo-lithography), etching (etch texture) technology of standard, purpose is to make silicon wafer 100 to have roughening institutional framework (texture), improves the optical efficiency of getting of solar cell to reduce reflection of incident light.Its etching solution for example is NaOH (NaOH) solution, and its ambient temperature can be approximately 90 ℃.Can soak hydrofluoric acid, hydrogen chloride in regular turn after etching finishes and further clean silicon wafer, again with washed with de-ionized water wafer surface impurity.
Then, carrying out ion injects to inject n-type ion (for example phosphonium ion) and p-type ion (for example boron ion) to form n-doped region 101 and p-doped region 102 respectively among wafer 100, the result forms the p-n doped structure of solar cell, please refer to Fig. 1.Above-mentioned formation n-type ion step can be utilized and feed phosphoric acid steam (POCl
3), oxygen (O
2) gas carries out in diffusion furnace tube, its ambient temperature can utilize quartz ampoule, nickel filament to be heated to 900-1100 ℃ for three sections.
After forming the p-n doped structure, utilize a non-grade to remove the oxide layer (native oxide layer) that is formed on the wafer 100 to being etched with, its etching solution can utilize NaOH (NaOH) solution, and its ambient temperature can be approximately 90 ℃.Similarly, can utilize hydrofluoric acid, hydrogen chloride further to clean silicon wafer 100 after the etching in regular turn, and then with washed with de-ionized water wafer 100 surface impurities.
Then, wafer 100 is placed in (annealing) technology of annealing in the boiler tube (furnace), makes p-type in the p-n doped structure and n-type ion can be distributed in more uniformly in separately the doped region.Similarly, its ambient temperature can utilize quartz ampoule, nickel filament to be heated to 900-1100 ℃ for three sections.
Afterwards, deposit a resilient coating (buffer layer) 103, please refer to Fig. 2.The material of resilient coating 103 comprises but is not defined as silica (SiO
2), silicon nitride (SiN
X), silicon oxynitride layer or its combination.For example, the preferred thickness of resilient coating 103 is the 50-70 nanometer.The present invention utilizes sputtering method to form resilient coating.Resilient coating 103 also can utilize conventional method to utilize aerating oxygen (O
2), nitrogen (N
2) or oxygen and nitrogen in reative cell (chamber), and by chemical vapor deposition (CVD), plasma activated chemical vapour deposition (PECVD) method, and on silicon wafer 100, form said silicon oxide, silicon nitride layer, silicon oxynitride layer or its combination.But this method is relatively more expensive, and wherein the reacting gas of silicon nitride layer (GasSource) comprises SiH
4(Silane), NH
3, N
2, H
2, it is as insulating barrier and resilient coating, and hardness and anti-aqueous vapor are preferable, that is it is preferred resilient coating, but it has higher dielectric constant.
Then, carry out a laser groove in resilient coating 103 upper surfaces and cut (Laser Grooving) technology, among resilient coating 103, form a plurality of groove patterns 104, please refer to Fig. 3.In other words, form a plurality of grooves 104 by laser aid cutting buffer-layer surface, laser aid for example is argon laser (Ar Laser), and power for example is 50 watts (W).For example, the width of each groove pattern is that 25-40 nanometer, the degree of depth are the 30-50 nanometer; In addition, groove pattern 104 comprises first's groove, and its spacing is 320 to 400 nanometers, and dispensed in parallel is in the surface of whole resilient coating, and the second portion groove, this vertical first of second portion groove groove, and its spacing is 320 to 400 nanometers.In addition, the method of laser lift-off also can be finished by beneath several laser species, for example: (1) Q-switch ruby laser (Q-switchedruby laser): it can send the ruddiness that wavelength is 694nm, and impulse duration is 20 to 50n-sec, and the output energy can reach 10J/cm
2(2) Q-switch Alexandria laser (Q-switchedAlexandrite laser): it can send the invisible light that wavelength is 755nm, and impulse duration is 50 to 100n-sec, and peak frequency is 1Hz; (3) Q-switch rubidium/Jacob laser (Q-switched Nd:YAGlaser): it can send the invisible light that wavelength is the 1054nm wavelength, and pulse frequency is 50kHz; (4) frequency multiplication Q-switch rubidium/Jacob laser (Frequency-doubled Q-switched Nd:YAG laser): with the crystal of Q switching rubidium/Jacob laser beam by potassium titanyl phosphate (KTP), the frequency of laser can increase to two times, and wavelength then reduces by half and is 532nm.
Generally speaking, can cause resilient coating/silicon fragment (silicon debris) to be formed at wafer 100 surfaces and recess sidewall during laser groove is cut and carried out, the result causes lattice defect or flaw.Therefore, laser groove can be carried out a groove cleaning after cutting, and it can utilize solution to corrode with dissolving resilient coating/silicon fragment, and its etching solution for example is NaOH and/or potassium hydroxide (NaOH/KOH) solution, and ambient temperature is about 45-60 ℃.In addition, since NaOH/potassium hydroxide (NaOH/KOH) solution can etch buffer layers (SiNO for example
4), if necessary, if desire the etched recesses sidewall, must use other etching solution according to this to a certain degree of depth.Similarly, can soak hydrofluoric acid, hydrogen chloride in regular turn after etching finishes and further clean silicon wafer, again with washed with de-ionized water wafer surface impurity.
Then, deposition the first metal layer 105 on above-mentioned resilient coating 103 and wafer 100, and fill up groove 104.The material of described the first metal layer 105 comprises but is not limited to aluminium (aluminium) or its alloy, its deposition process is to utilize evaporation, sputter (evaporation or sputtering) or the thin aluminum metal layer of hot-dip one to finish, its thickness is approximately the 1.5-3.0 micron, please refer to Fig. 4.Then, deposition second metal level 106 on the first metal layer 105, it is to utilize wire mark (screen printing) thicker aluminum metal layer to finish, the about 25-40 micron of its thickness please refer to Fig. 5.Generally speaking, second metal level 106 is a selectivity step, and its thickness is much larger than the thickness of the first metal layer 105.If need to utilize washed with de-ionized water or remove aluminium powder (dust).
Then, optionally on second metal level 106, form an anti-reflecting layer 107, please refer to Fig. 6.For example, described anti-reflecting layer comprises silicon nitride (SiO
2), cerium oxide (CeO
2), aluminium oxide (Al
2O
3), silicon nitride (Si
3N
4) or silicon nitride-titanium oxide (SiO
2-TiO
2), it can form by chemical vapor deposition (CVD), plasma activated chemical vapour deposition (PECVD) mode.The thickness of above-mentioned anti-reflecting layer is approximately the 0.06-0.1 micron.
By as can be known aforementioned, as thin as a wafer in the solar battery structure of silicon, silicon wafer thickness is about the 80-180 micron in miniaturization, therefore, because deformation takes place because of external force in thin excessively wafer thickness easily.The present invention mainly is to form a resilient coating 103 to change the structure of slimming silicon substrate in wafer 100 back sides.
Afterwards, carry out a sintering process (aluminium sintering), its be for the density that improves the solar battery p-n doped structure reducing the scission of link of silicon in the wafer, that is the so-called key that dangles (dangling bond).Silicon wafer can be inserted on implementing and be heated to a certain temperature on the quartz ampoule, for example 400-500 ℃, and feed hydrogen (H
2), nitrogen (N
2) or hydrogen and nitrogen, at least 25 minutes.The energy component level of the above-mentioned key that dangles (dangling bond) is just put the centre at energy gap.Because these a key tool one electronics that dangle can lose an electronics or hold an electronics again, therefore form defective, provide electronics-hole as the complex centre, make the carrier lifetime shorten and the material behavior variation.For example, electronics or hole that the phosphorus of doping or boron atom are disengaged may be caught by these defectives, and electrical conductivity can't change, thereby can't form p-n and connect face.
In like manner, the aluminum metal sintering process can soak hydrofluoric acid, the further clean wafers of hydrogen chloride after finishing in regular turn, again with washed with de-ionized water wafer surface impurity.
The present invention illustrates as above that with preferred embodiment so it is not in order to limit the protection range that the present invention advocated.All those of ordinary skill in the art all belong to the equivalence of being finished under the disclosed spirit and change or design, and should be contained in protection scope of the present invention in the change or the retouching that do not break away from the spirit or scope of the present invention to be done.
Claims (10)
1. the manufacture method of a solar cell, this method comprises:
Purchase substrate;
In substrate, inject ion to form the p-n doped structure with ion implantation technique;
On this substrate, form resilient coating;
Among this resilient coating, form groove; And
On this resilient coating, form metal level, and insert described groove.
2. the manufacture method of solar cell as claimed in claim 1, wherein said substrate comprises silicon wafer.
3. the manufacture method of solar cell as claimed in claim 1, the material of wherein said resilient coating comprises silica, silicon nitride, silicon oxynitride or their combination.
4. the manufacture method of solar cell as claimed in claim 1, wherein said formation groove is to finish by the laser groove cutting process.
5. the manufacture method of solar cell as claimed in claim 1, wherein said metal level is aluminum metal or aluminium alloy.
6. the manufacture method of solar cell as claimed in claim 1, wherein said metal level comprises the first metal layer and second metal level.
7. the manufacture method of solar cell as claimed in claim 1, this method also are included in the step that described ion carries out the described wafer surface of etching before injecting.
8. the manufacture method of solar cell as claimed in claim 1, this method also are included in the step that forms anti-reflecting layer after the described formation metal level on this metal level.
9. the manufacture method of solar cell as claimed in claim 8, the material of wherein said anti-reflecting layer comprises silicon nitride, cerium oxide, aluminium oxide, silicon nitride or silicon nitride-titanium oxide.
10. the manufacture method of solar cell as claimed in claim 8, this method is carried out sintering process after also being included in described formation anti-reflecting layer.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNA200710104807XA CN101312222A (en) | 2007-05-21 | 2007-05-21 | Method of manufacturing solar cell |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNA200710104807XA CN101312222A (en) | 2007-05-21 | 2007-05-21 | Method of manufacturing solar cell |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN101312222A true CN101312222A (en) | 2008-11-26 |
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CNA200710104807XA Pending CN101312222A (en) | 2007-05-21 | 2007-05-21 | Method of manufacturing solar cell |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102339894A (en) * | 2010-07-23 | 2012-02-01 | 上海凯世通半导体有限公司 | Method for manufacturing solar cell |
| CN104183668A (en) * | 2013-05-27 | 2014-12-03 | 住友重机械工业株式会社 | Manufacturing method of solar cell unit |
-
2007
- 2007-05-21 CN CNA200710104807XA patent/CN101312222A/en active Pending
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102339894A (en) * | 2010-07-23 | 2012-02-01 | 上海凯世通半导体有限公司 | Method for manufacturing solar cell |
| CN104183668A (en) * | 2013-05-27 | 2014-12-03 | 住友重机械工业株式会社 | Manufacturing method of solar cell unit |
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