CN102842640A - Method for preparing silicon crystal epitaxial layer and related crystalline silicon substrate structure - Google Patents
Method for preparing silicon crystal epitaxial layer and related crystalline silicon substrate structure Download PDFInfo
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- CN102842640A CN102842640A CN201110168792XA CN201110168792A CN102842640A CN 102842640 A CN102842640 A CN 102842640A CN 201110168792X A CN201110168792X A CN 201110168792XA CN 201110168792 A CN201110168792 A CN 201110168792A CN 102842640 A CN102842640 A CN 102842640A
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Abstract
The invention discloses a method for preparing a silicon crystal epitaxial layer comprising the following steps of: by using a known screen printing technology, uniformly coating a metal paste on at least one full surface of a crystalline silicon substrate, and enabling the crystalline silicon substrate to pass through a hyperthermia tunnel kiln at a transfer speed so as to grow a silicon crystal epitaxial film on the crystalline silicon substrate by the paste and crystalline silicon through the process of liquid phase epitaxy; and regulating the ingredients of doped elements in the formulation of the metal paste so as to control the silicon crystal layer to be a semiconductor with P-type conductive polarity or N-type conductive polarity. According to the method, the invention discloses a crystalline silicon substrate with a doped epitaxial layer.
Description
[technical field]
The invention belongs to the field of crystal silicon semiconductor film growth techniques.
This case utilizes screen printing technology, success at crystalline silicon substrate superficial growth one deck silicon polycrystalline film layer, by process technique of the present invention, can on the surface of crystal silicon substrate, adjust the surface characteristic of this crystal silicon substrate; For example; The kind, the content that mix; The control of conduction polarity (the conduction polarity of P type or N type) and crystal defect ... Deng, make to be suitable for silicon wafer type solar cell, silicon diode, silicon electric crystal, silicon thyristor respectively ... Application scenario Deng the silicon wafer semiconductor components and devices.The process apparatus that this case is implemented, the standard device for the industrialization volume production has cost advantage, and method is simple possible very also, and this case specifies it with the example that is made as of silicon wafer type solar cell.
[background technology]
Along with the crude oil of storage is petered out, the development that replaces the energy has been one trend, though wherein nuclear energy power generation is still main flow; But estimate to Christian era the year two thousand twenty; The whole world utilizes solar power generation will reach the layout of total generated energy of 100GWp, and develops the silicon wafer type solar cell in 60 years nearly, and occupying at present all, the cities of solar cell market more than ninety percent account for rate; Based on silicon is the abundantest in the world mineral reserve; Be about the earth's crust and form 26% of part,, add that this industry can overcome technological barrier one by one with mass production processing procedure and the scale that silicon wafer type solar cell has now; Improve the gesture of driving of generating efficiency, expectation silicon wafer type solar cell will be played the part of the dominant role of solar power generation future.
A large amount of at present silicon wafer type solar cell industry of making; All implement for the method for raising the efficiency with the spirit that can meet so-called Grid Parity; Even if therefore the verified feasible high efficiency structure in laboratory also all can't get into production line for the moment and make in a large number, but these laboratory of raising the efficiency demonstrations; But being still mass production silicon wafer type solar cell industry draws for improving the direction of efficient; (BSRV, Back Side Recombination Velocity is perhaps with S for example to reduce the surperficial electronics consolidation rate of silicon wafer type solar battery back
Eff(cm/s) represent it) promptly be a tangible illustration to raise the efficiency; In the silicon wafer type solar cell processing procedure of existing mass production; Utilize printing technology that a kind of conduction aluminium paste by metallic aluminium powder, glass granules, organic substance resin, solvent and the mixing one-tenth of various additive is coated in the crystal silicon substrate back side; Produced the aluminium back of the body (Al-BSF) through high temperature sintering; Just be based on this laboratory demonstration, with the electronics consolidation rate reduction on surface, a kind of illustration of raising the efficiency.
Yet this kind aluminium back of the body (Al-BSF) warp enforcement all the year round; Though the BSRV value that can provide is significantly improved; But generally still be higher than 400cm/s, and for making the large scale and the silicon wafer type solar cell of thinning day by day, this aluminium back of the body field causes easily the problem of chip warpage very serious; Make and the follow-up easy pressure break of module production, breakage cause considerable puzzlement.To improving a present stage aluminium back of the body electronics consolidation rate; People such as D.S.Kim point out that a kind of boron back of the body (B-BSF) of high temperature boron (Boron) diffusion process that utilizes can improve this problem (J.Electrochem.Soc.; Volume 157, and Issue 6, pp.H684-H687 (2010)); Its research report is pointed out; Efficient is feasible up to 19.7% silicon wafer type solar cell, and just the battery structure of the battery structure of this experiment and existing volume production and inconsistent need utilize yellow light lithography (PHOTO-LITHOGRAPHY) processing procedure; Just, back of the body metal electrode neither generally known printing process can make, being difficult to adopt immediately this high temperature boron (Boron) diffusion process to make boron back of the body field (B-BSF) at existing silicon wafer type manufacture of solar cells line should be the fairly obvious fact.
Say (20th European Photovoltaic Solar Energy Conference and Exhibition according to Frank Huster in addition; Barcelona; 6-10June 2005 Pre-Print; 2AO.2.1), an aluminium back of the body process that forms, aluminium paste finally can be fixed with the metal form of aluminium silicon eutectoid alloy (eutectic alloy) on silica-based backboard surface; And the crystalline silicon substrate of large scale and thinning day by day and this layer alusil alloy layer be based on the greatest differences of hot expansion property (CTE), the main cause that causes battery sheet warpage really.Frank Huster through behind-20 ℃～-50 ℃ freezing, can revert back to flat condition again with the solar battery sheet of warpage under room temperature; This method is worth further assessment, and it introduces the well-formedness of volume production processing procedure, but most solar cell producer hopes that all easy solution can be arranged, rather than increases the complexity of processing procedure; Conduction aluminium paste supply producer there's no one who doesn't or isn't adjusts the expectation that prescription hopes to reach the client for this reason with beating one's brains.
In addition, about the research that solar cells made of crystalline silicon reduces cost, direction is almost all pointed to and is reduced the various measures of using silicon metal raw material or exploitation alternative material.In the research that Germany, the U.S., Japan and other countries are correlated with over 20 years; Comparatively feasible way is come manufacturing solar cells with regard to the crystalline silicon substrate that is to use a kind of low cost to be called metallurgical grade silicon (metallurgical grade Silicon) raw material made, or uses the few film-type silicon wafer solar cell of silicon raw material.Period early, CANON (Canon Kabushiki Kaisha, Tokyo; JP) be devoted in this respect research; Have a series of United States Patent (USP) can be for reference, wherein US 6,869; The substrate manufacture silicon wafer solar cell that 863 Fabrication process of solar cell utilize the brilliant technology of liquid built to process at metallurgical grade silicon, its efficiency value are about seventy percent of use high-purity silicon wafer substrate; (2010/7 month) Germany company of section (IMEC) of liking to be beautiful uses the grow reflectance coating of three road epitaxial layers and a kind of labyrinth of gas phase crystal technique of heap of stone on this kind substrate in the recent period; Its report gives a title and is called " wafer is equal to " substrate (" wafer equivalent " substrate), this substrate utilizes the industrialized standard processing procedure to produce area 70cm
2The silicon wafer solar cell, efficiency value further reaches 14.7% achievement, almost has been equal to the efficiency value of present industrial production silicon wafer solar cell.
Be appreciated that by above two examples; The crystal silicon substrate that utilizes cheap low-purity silicon materials to process; Still need through a kind of processing procedure of film growth; The efficiency value of lifting silicon wafer solar cell that could be successful, but so-called liquid built is brilliant, gas phase crystal technique of heap of stone, is not the existing standardization processing procedure of silicon wafer solar cell; Even if the latter releases " wafer is equal to " substrate can directly apply to the standardization processing procedure of silicon wafer solar cell, whether its price can be equal to the degree that the dealer can accept will be a test.
Aluminium aluminum back surface field about existing crystal silicon solar batteries; Generally all hoping can to fire journey (co-firing) altogether long as much as possible thick so-called, even can reach the above thickness of 10 μ (micron), but the what is called that is limited by positive silver-colored conductive paste is burnt the misgivings that P/N ties (P/N junction); Burning (co-firing) processing procedure spike temperature altogether can't arbitrarily heighten; For example, the spike temperature more than 850 ℃ adds that more or less worried battery sheet produces the problem of warpage; Even problem of appearance such as the pill of aluminium, chain streak are burnt in the aluminium conductive paste surface at the back side; Very puzzlement, under therefore trading off, an aluminium back of the body thickness of general crystal silicon solar batteries is about 2.0 μ (micron)～6.0 μ (micron).
In addition; The aluminium at the existing crystal silicon solar batteries back side back of the body is not a kind of structure of full surface (full area), because the arrangement on processing procedure, (supplying the welding rod welding) back of the body silver normally prints coating prior to aluminium paste; Purpose is to make back of the body silver directly be attached on the back of the body surface of crystal silicon battery; Compared to more firm, in the welding rod connection process of module, be easier to the higher event of welding and value of thrust attached to its adhesive force on the aluminium paste.
Based on above various reasons; This case discloses a kind of innovation " wafer is equal to " pdm substrate; And manufacturing approach; Uniform in thickness can be provided and carry on the back the field, also can avoid the battery sheet to produce problems such as outward appearance or warpage simultaneously greater than full surface (full area) aluminium of 6.0 μ (micron) and surperficial high conductive characteristic.The enforcement of this technology; System utilizes the screen printing technology, on the surface of crystalline silicon substrate, is coated with layer of metal aluminum slurry at least, passes through the processing procedure of high temperature Fast Sintering subsequently; Make crystalline silicon substrate grow one deck silicon polycrystalline film layer in dispensing area; This layer silicon membrane layer promptly is equal to so-called aluminium back of the body field, and the way of being implemented is the standardization processing procedure of solar cells made of crystalline silicon, and correlative detail will narration in detail in next joint.
Based on the implementing method that this case disclosed, to coincide with solar cells made of crystalline silicon producer existing procedure for producing, this brute force that will be this case has a high feasibility proves, is that the brute force that can meet Grid Parity guarantees.Crystal silicon solar batteries processing procedure solution provided by the invention comprises fabrication steps, parameter, metal paste prescription and a kind of innovation
Silicon metal " wafer is equal to " board structure.According to this case implementing method, will be can reach with rational manufacturing cost to promote solar cells made of crystalline silicon efficient, reduce cost and improve in the lump, solve outward appearance, the warpage issues of battery sheet a kind of innovative technology, reach a kind of innovative product.For stakeholder with experiences or backgrounds such as general solar cells made of crystalline silicon components and parts processing procedure, thin film manufacture process; Perhaps because the technology of perhaps deriving in the fabrication steps of adjusting this case and being disclosed a little, process parameter, prescription derived from the implementation method of perhaps utilizing this case in fabrication steps that this case disclosed, process parameter, the relevant prescription; Or use this technology whole or local in the structure of relevant components and parts, all will be regarded as the part of the claim that institute of the present invention desire discloses.
[summary of the invention]
The enforcement of this case utilizes a kind of known screen printing technology; A kind of metal paste is coated on uniformly at least one surface of crystalline silicon substrate; Thickness range is 5.0 μ (micron)～300.0 μ (micron), and afterwards, this crystal silicon substrate passes through hyperthermia tunnel Kiln with a kind of transfer rate; Make slurry and silicon metal produce reaction, and on crystalline silicon substrate, grow one deck silicon polycrystalline film layer.
The reaction that metal paste and silicon metal produce, according to the preset temperature in each district of tunnel cave, carry out in regular turn with following process:
During 1 120 ℃～300 ℃ of processes, with being printed on slurry oven dry on the crystal silicon substrate, fixed;
During 2 300 ℃～600 ℃ of processes, the organic substance in the ease plasma burning material is formed part;
During 3 400 ℃～900 ℃ of processes, the metal group composition in the slurry begins melting, silicon wafer also dissolves in the molten metal gradually,
During 4 700 ℃～1000 ℃ of processes, silicon reaches capacity in molten metal;
Process 5 is reduced to room temperature, and one deck silicon wafer thin layer (thin film) is separated out and on silicon substrate, grown to the silicon in the solution because of supersaturation;
At last, the metal level on the silicon substrate is removed, is combined the crystal silicon substrate of script to become a kind of " wafer is equal to " crystal silicon substrate.
According to above-mentioned processing procedure, coupling process temperatures, transfer rate, formula of size and printing thickness thereof ... Deng, can make have thickness 6.0 μ (micron) above silicon polycrystalline film layer " wafer is equal to " crystal silicon substrate; The silicon polycrystalline film layer of this substrate has characteristic of semiconductor, and resistance (Resistivity) scope on surface is 0.0001 Ω cm～1.0 Ω cm.The configuration of surface microcosmic is level and smooth surface, and its characteristic is extended from employed substrate fully, for example crystallographic direction, crystalline form, outward appearance ... Deng; Can pass through surface grinding, polishing, promptly applicable to the application scenario of crystal silicon solar batteries.
Through a kind of modulation of metal paste prescription, the present invention utilizes above-mentioned flow process, can on the P type crystal silicon substrate more than resistance (Resistivity) the 0.05 Ω .cm, make the P of thickness at least 6.0 μ (micron)
+Type silicon polycrystalline film layer, making its surperficial resistance (Resistivity) scope is 0.0001 Ω .cm～1.0 Ω .cm.This P
+Type silicon polycrystalline film layer can be used as N
+/ P/P
+A kind of back of the body field of crystal silicon solar batteries structure can substitute existing P/P
+: Al aluminium back of the body field.In addition, the modulation through another kind of metal paste prescription utilizes above-mentioned flow process, and the present invention can make the N of thickness at least 6.0 μ (micron) on the N type crystal silicon substrate more than resistance (Resistivity) the 0.05 Ω .cm
+Type silicon polycrystalline film layer, making its surperficial resistance (Resistivity) scope is 0.0001 Ω .cm～0.8 Ω .cm.This N
+Type silicon polycrystalline film layer can be used as P
+/ N/N
+So-called
Back of the body knot back electrode formulaA kind of positive field of (BJ BC) crystal silicon solar batteries can substitute phosphorus (POCl
3) diffusion made N/N
+: positive of P.
The selection of the metal group composition in the metal paste prescription, main system is to select important document with the metal that silicon wafer can dissolve altogether, for example: aluminium, copper, silver, gold, tin, gallium, indium, lead ... Deng simple metal; Or alloy, for example: aluminum bronze, gallium aluminium, aluminium indium, aluminium tin, aluminium silicon ... Deng aluminium alloy or silver alloy, billon, copper alloy ... Deng the particulate of alloy, or the particulate that mixes each other in proportion of simple metal etc. for it.In the metal paste prescription; This metal group composition is main composition; In the present invention, be called first metal particle; According to the equilbrium phase diagram that dissolves each other (phase diagram) or the solubility graph of relation (solubility curve) of element silicon and metal, determine the growth spike temperature (peak temperature) of silicon polycrystalline film layer and the temperature in each district of tunnel cave to set.
The conduction polarity of silicon polycrystalline film layer depends on doping (dopant) the composition part or the metal group composition of metal paste prescription, in the present invention, is called second metal particle.The N type semiconductor that general crystal silicon semiconductor is commonly used mix (dopant) have arsenic, phosphorus, antimony, tellurium, cadmium, sulphur ... Element Deng periodic table five, sexavalence; P type semiconductor doping (dopant) has beryllium, magnesium, strontium, barium, zinc, aluminium, indium, bismuth, gallium, boron, stone roller ... Element Deng periodic table two, trivalent.So the doping (dopant) of metal paste prescription is formed part except separately; Or according to outside a kind of these elementary particles of mixed proportion use; Also can use its oxide, halide, organo-metallic compound ... Kenel Deng particulate or organic colloid; Make it to be dispersed in the slurry, when the silicon polycrystalline film layer is grown up, be dissolved in wherein, growing semiconductor conduction polarity is the silicon polycrystalline film layer of P type or N type respectively; And its electronics or electric hole concentration are increased by nexine to the surface of thin layer gradually, and the carrier concentration (carrier concentration) on surface can be controlled at 0.1 * 10 usually
17Cm
-3～8.0 * 10
20Cm
-3Scope.
Composition part in the metal paste prescription, except above-mentioned composition especially, also have organic resin, solvent and various micro-additive; Main purpose is to control the tackness (viscosity) of slurry to promote its printing, for example, passes through film property, rheological characteristic; And the uniformity of rolling refining (3-rollers mixing) disposed slurry, these nonmetal composition parts, this case system is called auxiliary agent; This auxiliary agent can burn mistake (burn out) when high temperature; General all with the gas form disengaging of water and carbon dioxide, the carbon or the carbide that still also have a little are residual, do not have for conductivity to have a strong impact on.To problems such as the outward appearance of battery sheet, warpages, the present invention is after the silicon polycrystalline film layer is grown up, and the surface can be passed through chemical corrosion through the metal level of high temperature sintering and handle, and it is completely cleared, problems such as the outward appearance of the cell back aluminium of needn't worrying fully or warpage.After metal level is handled, finally expose a kind of low-resistance (for example 3.0 * 10
-4The top layer of silicon polycrystalline film Ω .cm), the configuration of surface of this silicon polycrystalline film, microcosmic is level and smooth surface, in the application scenario of crystal silicon solar batteries, needn't pass through surface grinding, polishing, and is promptly applicable.In addition, the silver-colored conductive paste of the back of the body can be directly printed on this silicon polycrystalline film top layer, becomes backplate through burning (co-firing) altogether.For some crystal silicon solar batteries structure, when its positive silver needs higher sintering temperature, for example, and when being greater than or equal to 835 ℃, problems such as the back of the body aluminium outward appearance of original processing procedure of needn't worrying fully or battery sheet warpage.
In addition, a kind of innovation structure (Fig. 3) that this case discloses is set up a kind of reflector that has higher reflectivity for the light of infrared ray wave band at cell backside,, Accuflect for example
TMThe reflector, how its reflectivity has the reflection characteristic of 95% above total reflectivity, the photoelectric efficiency that can promote battery how during rice in rice～2,500 in wave-length coverage 700.
[description of drawings]
Fig. 1-1, P/P-sub./P
+" wafer is equal to " crystal silicon substrate
The P/P-sub./P of Fig. 1-2, surface coarsening
+" wafer is equal to " crystal silicon substrate,
Fig. 2, a kind of silicon wafer solar cell are made flow process
Fig. 3, utilize the P/P-sub./P of surface coarsening
+" wafer is equal to " crystal silicon substrate makes the graphic of a kind of silicon wafer solar battery structure
The main element symbol description:
1.001 P type crystal silicon substrate (P-sub.)
2.010 P type silicon polycrystalline film layer
3.011 P
+The boron back of the body (B:BSF) silicon polycrystalline film layer
4.012 the P type silicon polycrystalline film layer of surface coarsening
5.014 backside reflection layer (BSR, Back Side Reflector)
6.030 P/N ties (P/N junction)
7.040 front anti-reflective film (ARC)
8.050 back silver lead electrode
9.060 positive silver-colored lead electrode
[embodiment]
For implementation content of the present invention more specifically is described, Yu Benjie utilizes embodiment progressively to illustrate fabrication steps, parameter or prescription content, but does not represent the present invention to be only applicable to the scope of this example.
Embodiment one, boron doping aluminium paste (B-doped Al paste) prescription;
-prescription is formed part: (%, percentage by weight)
1. first metal particle: aluminium: 90.00%～99.99%
2. second metal particle: boron:
0.01%～10.00%
Add up to (auxiliary agent does not count): 100.0%
3. auxiliary agent; In right amount, generally in the slurry total weight, approximately occupy 10.0%～30.0% percentage by weight.
-metal particle specification:
※ aluminum metal particulate: the metal particle of purity 99.9%～99.9999%, particle size range 0.01 μ (micron)～20.0 μ (micron)
※ boron doping particulate: the metal particle of purity 99.9%～99.9999%, particle size range 0.01 μ (micron)～20.0 μ (micron)
(above particulate is habitual kenel with ball-type, but is not limited to the particulate of this external form kenel.)
-slurry viscosity (viscosity): 10～500PaS
(Bu Shi method of testing; Brookfield, #14,10rpm, 25 ℃)
Embodiment two, P/P-sub./P
+" wafer is equal to " processing procedure of crystal silicon substrate and structure present embodiment be with the P type " wafer is equal to " crystal silicon substrate is example, its main manufacturing process and process parameter, equipment are explained as follows in regular turn;
Step 1: silicon substrate chemical corrosion, cleaning;
Wherein,
Resistance (Resistivity) specification of P type crystal silicon substrate is more than the 0.05 Ω .cm, thickness 80.0 μ (micron)～250.0 μ (micron);
Step 2: P
+The silicon polycrystalline film layer is grown up;
Step details contains;
Arbitrary surface in two surfaces of-crystal silicon substrate imposes P type boron adulterated al metal slurry printing coating,
-hyperthermia tunnel Kiln film growth;
And the temperature gradient distribution that is set to relative superiority or inferiority low (IR lamp source, top to driving chain surface) of high-temperature region, 300.0 ℃～980.0 ℃ of its spike temperature (peak temperature) scopes,
(to remove the fixed metal paste in surface) cleaned in-chemical corrosion ... Etc. details.
Its thickness range of silicon polycrystalline film layer that grows up to is 6.0 μ (micron)～20.0 μ
(micron); Surface resistance (Resistivity) scope is 0.0001 Ω .cm～1.0 Ω .cm;
Step 3: P type silicon polycrystalline film layer is grown up;
Step details contains;
Another surface in two surfaces of-crystal silicon substrate imposes P type indium doped tin metal slurry printing coating,
-hyperthermia tunnel Kiln film growth;
And the temperature gradient distribution that is set to relative superiority or inferiority low (IR lamp source, top to driving chain surface) of high-temperature region, 300.0 ℃～980.0 ℃ of its spike temperature (peak temperature) scopes,
(to remove the fixed metal paste in surface) cleaned in-chemical corrosion ... Etc. details.
Its thickness range of silicon polycrystalline film layer that grows up to is 6.0 μ (micron)～20.0 μ
(micron); The carrier concentration (carrier concentration) on surface is controlled
Built in scope is 0.5 * 10
17～2.0 * 10
18Cm
-3
The output of present embodiment is called the P type " wafer is equal to " crystal silicon substrate, can replace existing silicon wafer solar base plate, be a kind of new wound structure (Fig. 1), have following characteristics:
1.P two surfaces of type crystal silicon substrate respectively have a full surface silicon polycrystalline thin film layer;
2. one of them superficial layer is surperficial low resistance (Resistivity) P
+Type silicon polycrystalline film layer; Its thickness range 6.0 μ (micron)～20.0 μ (micron), surperficial resistance (Resistivity) scope is 0.0001 Ω .cm～1.0 Ω .cm
3. wherein another surface is P type doped silicon polycrystalline thin film layer; Its thickness range 6.0 μ (micron)～20.0 μ (micron); The carrier concentration on surface is controlled at scope 0.5 * 10
17～2.0 * 10
18Cm
-3
The P type " wafer is equal to " crystal silicon substrate is applicable to existing silicon wafer solar cell processing procedure; More can on existing processing procedure basis, make more high efficiency silicon wafer solar battery structure; For example the silicon wafer solar cell of SE (Selective Emitter) structure can be silicon wafer solar cell dealer a kind of effective solution is provided.
Embodiment three, N/N-sub./N
+" wafer is equal to " processing procedure of crystal silicon substrate and structure present embodiment be with the N type " wafer is equal to " crystal silicon substrate is example, its main manufacturing process and process parameter, equipment are explained as follows in regular turn;
Step 1: silicon substrate chemical corrosion, cleaning;
Wherein,
Resistance (Resistivity) specification of N type crystal silicon substrate is more than the 0.05 Ω .cm, thickness 80.0 μ (micron)～250.0 μ (micron);
Step 2: N
+The silicon polycrystalline film layer is grown up;
Step details contains;
Arbitrary surface in two surfaces of-crystal silicon substrate imposes N type arsenic doping silver metal slurry printing coating,
-hyperthermia tunnel Kiln film growth;
And the temperature gradient distribution that is set to relative superiority or inferiority low (IR lamp source, top to driving chain surface) of high-temperature region, 835.0 ℃～980.0 ℃ of its spike temperature (peak temperature) scopes,
(to remove the fixed metal paste in surface) cleaned in-chemical corrosion ... Etc. details.
Its thickness range of silicon polycrystalline film layer that grows up to is 6.0 μ (micron)～20.0 μ
(micron); Surface resistance (Resistivity) scope is 0.0001 Ω .cm～0.8 Ω .cm;
Step 3: N type silicon polycrystalline film layer is grown up;
Step details contains;
Another surface in two surfaces of-crystal silicon substrate imposes antimony doped tin metal slurry printing coating,
-hyperthermia tunnel Kiln film growth;
And the temperature gradient distribution that is set to relative superiority or inferiority low (IR lamp source, top to driving chain surface) of high-temperature region, 300.0 ℃～980.0 ℃ of its spike temperature (peak temperature) scopes,
(to remove the fixed metal paste in surface) cleaned in-chemical corrosion ... Etc. details.
Its thickness range of silicon polycrystalline film layer that grows up to is 6.0 μ (micron)～20.0 μ
(micron); The carrier concentration (carrier concentration) on surface is controlled
Built in scope 0.5 * 10
17～2.0 * 10
18Cm
-3
The output of present embodiment is called the N type " wafer is equal to " crystal silicon substrate, can replace existing silicon wafer solar base plate, be a kind of new wound structure, have following characteristics:
1.N in two surfaces of type crystal silicon substrate, respectively have a full surface silicon polycrystalline thin film layer;
2. one of them superficial layer is surperficial low resistance (Resistivity) N
+The silicon polycrystalline film layer; Its thickness range 6.0 μ (micron)～20.0 μ (micron), surperficial resistance (Resi stivity) scope is 0.0001 Ω .cm～0.8 Ω .cm
3. wherein another surface is N type doped silicon polycrystalline thin film layer; Its thickness range 6.0 μ (micron)～20.0 μ (micron); The carrier concentration on surface is controlled at scope 0.5 * 10
17～2.0 * 10
18Cm
-3
The N type " wafer is equal to " crystal silicon substrate can quicken the replacement of existing silicon wafer solar cell processing procedure, so make to have the main flow that the N type silicon wafer solar cell of high efficiency potentiality more more can become next ripple silicon wafer solar cell ahead of time.
Embodiment four, a kind of silicon wafer solar cell are made flow process;
Present embodiment is with P/P-sub./P
+" wafer is equal to " crystal silicon substrate, mate the example that is embodied as of existing crystal silicon solar batteries volume production flow process, make N/P/P
+The crystal silicon solar batteries of structure, its manufacturing process and details are explained as follows in regular turn;
Step 1: silicon substrate chemical corrosion, cleaning, surface coarsening etching processing procedures such as (texture etching);
Wherein,
Resistance (Resistivity) specification of P type crystal silicon substrate is more than the 0.05 Ω .cm, thickness 80.0 μ (micron)～250.0 μ (micron);
Step 2: P/N. knot (P/N junction) is made;
Step details contains;
-phosphoric acid (POCl
3) the steaming mist;
-900 ℃～1000 ℃ High temperature diffusion 0.5～1.5 hour;
-phosphorosilicate glass (PSG) chemical scavenging, substrate clean
Etc. details.
Make its N layer thickness of diffusion layer be about 0.1 μ (micron)～1.0 μ (micron);
Surface resistance (Resistivity) scope is 0.0001 Ω .cm～0.0005 Ω .cm;
Step 3: positive antireflection plated film (ARC);
With low temperature PECVD method cvd nitride silicon thin film, the about 400nm of thickness range (how rice)～800nm (how rice), fine and close free of pinholes;
Step 4: backside reflection layer (BSR) processing procedure
A kind of coating of high dielectric slurry, oven dry; It has how rice～2,500 rice how of infrared wavelength range 700, the reflection characteristic of 95% above total reflectivity, about 1.0 μ of thickness range (micron)～3,000.0 μ (micron).
Step 5: positive, back silver lead electrode is fired journey altogether;
Step details contains
The printing of-back side P type welding silver slurry, drying;
The printing of-positive N type silver slurry;
-hyperthermia tunnel Kiln spike temperature (peak temperature) is burnt (co-firing) for 730 ℃～830 ℃ altogether
Etc. details;
Step 6: battery sheet periphery Isolation (insulation) handles, test ... Deng
More than narration can be with reference to the process step of figure 2.
The solar battery structure of present embodiment manufacturing has as follows:
1. one kind
Back of the body field, full surfaceThe solar battery structure of (full area BSF), a back of the body thickness can increase to 6.0 μ (micron)～20.0 μ (micron) scope,
2. has low surface impedance value, the boron back of the body field of 0.0001 Ω .cm～1.0 Ω .cm
(B:BSF)，
3. back of the body silver soldering connects lead replacement back of the body aluminium conductive layer, becomes the backplate of solar cell,
4. have back side 450nm (how rice)～2500nm (how rice) reflector (BSR, Back Side Reflector) of reflectivity more than 95%,
Characteristics like Fig. 3.
By the fabrication steps details of above exposure, generally be familiar with the stakeholder of silicon wafer manufacture of solar cells processing procedure, should be easy to just find P/P-sub./P of the present invention
+" wafer is equal to " crystal silicon substrate can implement at existing processing procedure and equipment fully.
Claims (10)
1. a method of making the silicon wafer epitaxial layer is characterized in that, the method at crystal silicon substrate surface formation doping silicon polycrystalline film comprises:
Utilize printing process the aluminum metal slurry to be printed on the surface of substrate; Pass through the processing procedure of one high temperature rapid firing again, the aluminum metal particulate melting at high temperature in the slurry, for example 800 ℃～1000 ℃; The silicon materials on the substrate top layer of feasible contact dissolve in the molten metal; Be cooled to room temperature subsequently gradually, make in the aluminum metal liquid silicon generation supersaturation and on silicon substrate, grow one deck silicon polycrystalline film again, its thickness is directly proportional with the spike temperature of setting; The present invention is a standard to reach the above thickness of 6.0 μ (micron), and the architectural feature of its rete is extended from substrate fully; On the substrate the alusil alloy layer of sintering curing utilize a kind of processing procedure of chemical corrosion, remove fully, the film silicon wafer exposes becomes a kind of new surface of substrate; Its configuration of surface microcosmic is level and smooth surface; In addition, the characteristic of semiconductor of this film is different from the characteristic of original crystal silicon substrate
Wherein each item programming main points are following:
First, crystal silicon substrate;
The crystal silicon substrate; Common name for crystalline state monocrystalline or polycrystalline silicon substrate; The full-size of crystal silicon solar batteries use at present is 5 cun monocrystalline side's sheets and 6 cun polycrystalline side's sheets; P type crystal silicon substrate, more than resistance (Resistivity) the specification 0.05 Ω .cm, its thickness 120.0 μ (micron)～220.0 μ (micron)
The prescription of second, metal paste;
The metal paste prescription contains first metal particle, i.e. aluminum metal particulate and a kind of
ColloidMix
Auxiliary agentThe two evenly mixes made slurry, and viscosity (viscosity) scope 10～500PaS is applicable to printing process, particularly the printing process of crystal silicon solar batteries;
And,
The metal particle specification: the metal particle of purity 99.9%～99.9999%, particle size range 0.01 μ (micron)～20.0 μ (micron), ball-type is habitual kenel, but is not limited to the particulate of this external form kenel;
And,
Auxiliary agent contains the additive of solvent, organic resin and various promotion metal paste uniformity and printing, is referred to as auxiliary agent;
The third, printing process
The thickness range that metal paste is printed is 5.0 μ (micron)～300.0 μ (micron), and at least one of covering crystal silicon substrate be the surface entirely
Fourth, high temperature rapid firing processing procedure
The hyperthermia tunnel Kiln processing procedure that utilizes a kind of crystal silicon solar batteries commercialization volume production to be designed; With a kind of transfer rate, for example per minute is 4.0 meters with the substrate that is printed with metal paste, continuously through each predefined warm area; Omnidistance only several minutes consuming time, so with " fast burning " processing procedure is referred to as
Penta, the growing principle of silicon polycrystalline film
Utilize the brilliant principle of liquid built, silicon materials reach capacity with the molten metal of melting when high temperature, and when cooling, separate out and be deposited on a kind of film growth method of progressive additive on the crystal silicon substrate because of the silicon supersaturation in the molten metal
Oneself, chemical corrosion processing procedure
Metal paste is attached on the crystal silicon substrate through the bonding course that presents a kind of alusil alloy behind the high temperature rapid firing; Utilize and a kind ofly can corrode this metal fully but do not handle with the medicament of silicon wafer reaction; Soak in for example 30 ℃～70 ℃ the aqueous hydrochloric acid solution, the top layer silicon polycrystalline film of crystal silicon substrate is exposed.
2. the method for making silicon wafer epitaxial layer according to claim 1 is characterized in that, said first metal particle is the metal particle that can dissolve altogether with silicon wafer, except aluminium, and copper, silver, gold, gallium, indium, lead, tin ... Deng simple metal; Or alloy, for example: aluminum bronze, gallium aluminium, aluminium indium, aluminium tin, aluminium silicon ... Deng aluminium alloy, or silver alloy, billon, copper alloy ... Deng the particulate of alloy, or the particulate that mixes each other in proportion of simple metal etc. all should be as first metal particle.
3. the crystal silicon board structure of processing according to the said method of claim 1 is characterized in that having P
+(boron: back of the body field) the P type crystal silicon substrate of layer;
Use following metal-doped formula of size,
And at least one full superficial growth goes out one deck and has boron doped silicon layer on crystal silicon substrate; Structure is like P-sub./P
+: B;
Wherein,
P + : BLayer specification:
Thickness range (micron): 6.0～20.0,
Surface morphology: two kinds of selections of planarization or alligatoring
Surface Standard resistance range (Ω .cm): 0.0001～1.0.
4. the crystal silicon board structure of processing according to the said method of claim 1 is characterized in that having N
+The N type crystal silicon substrate of (arsenic: positive) layer;
Use following doping metals formula of size,
And at least one full superficial growth goes out the silicon layer that one deck has arsenic doping on crystal silicon substrate; Structure is like N-sub./N
+: As;
Wherein,
N + : AsLayer specification:
Thickness range (micron): 6.0～20.0,
Surface morphology: two kinds of selections of planarization or alligatoring
Surface Standard resistance range (Ω .cm): 0.0001～1.0.
5. a crystal silicon board structure is characterized in that, has positive P silicon wafer thin layer and back side P
+(boron: back of the body field) the P type crystal silicon substrate of layer;
It uses following two kinds of doping metals formula of size,
One of (back side P
+Metal paste);
Two (metal pastes of positive P);
And, according to the process step of embodiment two, the difference silicon growth layer crystal layer in the upper and lower full surface of crystal silicon substrate; Structure is like P:In/P-sub./P
+: B;
Wherein,
P:InLayer specification:
Thickness range (micron): 6.0～20.0
Surface morphology: two kinds of selections of planarization or alligatoring
Surface carrier concentration scope (cm
-3): 0.5 * 10
17～2.0 * 10
18
P + : BLayer specification:
Thickness range (micron): 6.0～20.0
Surface morphology: two kinds of selections of planarization or alligatoring
Surface Standard resistance range (Ω .cm): 0.0001～1.0.
6. a crystal silicon board structure is characterized in that, a kind of have positive N silicon wafer thin layer and a positive N
+The N type crystal silicon substrate of (arsenic: positive) layer;
It uses following two kinds of doping metals formula of size,
One of (positive N
+Metal paste);
Two (metal pastes of back side N);
And, according to the process step of embodiment three, the difference silicon growth layer crystal layer in the upper and lower full surface of crystal silicon substrate; Structure is like N:Sb/N-sub./N
+: As;
Wherein,
N:SbLayer specification:
Thickness range (micron): 6.0～20.0
Surface morphology: two kinds of selections of planarization or alligatoring
Surface carrier concentration scope (cm
-3): 0.5 * 10
17～2.0 * 10
18
N + : AsLayer specification:
Thickness range (micron): 6.0～20.0
Surface morphology: two kinds of selections of planarization or alligatoring
Surface Standard resistance range (Ω .cm): 0.0001～0.8.
7. according to the crystal silicon board structure under claim 3 or the claim 5; It is characterized in that; Second metal particle in the said metal paste prescription is a P type doped chemical (dopant); Except boron, the indium, the element of periodic table two, trivalent, beryllium, magnesium, strontium, barium, zinc, aluminium, bismuth, gallium, stone roller ... Deng all should be as second metal particle.Except separately, or more than one mix in proportion, use these elementary particles during use; Also can use its oxide, halide, organo-metallic compound ... Kenel Deng particulate or organic colloid.
8. according to the crystal silicon board structure under claim 4 or the claim 6, it is characterized in that second metal particle in the described metal paste prescription is a N type doped chemical (dopant), except arsenic, the antimony, the element of periodic table five, sexavalence; Phosphorus, tellurium, cadmium, sulphur ... Deng all should be as second metal particle.Except separately, or more than one mix in proportion, use these elementary particles during use; Also can use its oxide, halide, organo-metallic compound ... Kenel Deng particulate or organic colloid.
9. a kind of silicon wafer solar battery structure that utilizes the described crystal silicon substrate manufacturing of claim 5 is characterized in that:
Making flow process (with reference to figure 2) with embodiment four; The position of P/N knot is in the scope of the upper strata of crystal silicon substrate P type silicon wafer thin layer in its structure, and comparatively favourable implementing measure makes the position of P/N knot approaching as far as possible surperficial; The degree of depth of 0.3 μ (micron)～1.0 μ (micron) for example
The backplate part is passed backside reflection layer (BSR) and is connected with a back of the body surface, and the layout shape of electrode can evenly distribute and module stage welding rod convenient welding, firmly serve as mainly consideration with electric current.
10. the step 2 of the process step of embodiment two and step 3 merge a kind of corrective measure of enforcement; Be a kind of step of burning altogether, under same high temperature rapid firing condition, the upper and lower surface of substrate is the growing silicon crystal film simultaneously; Afterwards, implement chemical corrosion more together, clean, the metal paste of just removing, back of the body surface is fixed.
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| WO2016065940A1 (en) * | 2014-10-31 | 2016-05-06 | Byd Company Limited | Solar cell unit, solar cell array, solar cell module and manufacturing method thereof |
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