TWI513021B - Solar cell and its manufacturing method - Google Patents
Solar cell and its manufacturing method Download PDFInfo
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- TWI513021B TWI513021B TW100132858A TW100132858A TWI513021B TW I513021 B TWI513021 B TW I513021B TW 100132858 A TW100132858 A TW 100132858A TW 100132858 A TW100132858 A TW 100132858A TW I513021 B TWI513021 B TW I513021B
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- 238000004519 manufacturing process Methods 0.000 title claims description 20
- 239000000758 substrate Substances 0.000 claims description 70
- 239000013078 crystal Substances 0.000 claims description 35
- 238000000034 method Methods 0.000 claims description 29
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 claims description 15
- 238000005530 etching Methods 0.000 claims description 15
- KWYUFKZDYYNOTN-UHFFFAOYSA-M Potassium hydroxide Chemical compound [OH-].[K+] KWYUFKZDYYNOTN-UHFFFAOYSA-M 0.000 claims description 12
- 239000007864 aqueous solution Substances 0.000 claims description 12
- 230000015572 biosynthetic process Effects 0.000 claims description 11
- CDBYLPFSWZWCQE-UHFFFAOYSA-L Sodium Carbonate Chemical compound [Na+].[Na+].[O-]C([O-])=O CDBYLPFSWZWCQE-UHFFFAOYSA-L 0.000 claims description 8
- BWHMMNNQKKPAPP-UHFFFAOYSA-L potassium carbonate Chemical compound [K+].[K+].[O-]C([O-])=O BWHMMNNQKKPAPP-UHFFFAOYSA-L 0.000 claims description 8
- 238000003486 chemical etching Methods 0.000 claims description 6
- 229910000027 potassium carbonate Inorganic materials 0.000 claims description 4
- 229910000029 sodium carbonate Inorganic materials 0.000 claims description 4
- BVKZGUZCCUSVTD-UHFFFAOYSA-N carbonic acid Chemical compound OC(O)=O BVKZGUZCCUSVTD-UHFFFAOYSA-N 0.000 claims 1
- XONPDZSGENTBNJ-UHFFFAOYSA-N molecular hydrogen;sodium Chemical compound [Na].[H][H] XONPDZSGENTBNJ-UHFFFAOYSA-N 0.000 claims 1
- 238000006243 chemical reaction Methods 0.000 description 10
- 230000000694 effects Effects 0.000 description 9
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 8
- KFZMGEQAYNKOFK-UHFFFAOYSA-N Isopropanol Chemical compound CC(C)O KFZMGEQAYNKOFK-UHFFFAOYSA-N 0.000 description 6
- BQCADISMDOOEFD-UHFFFAOYSA-N Silver Chemical compound [Ag] BQCADISMDOOEFD-UHFFFAOYSA-N 0.000 description 6
- UIIMBOGNXHQVGW-UHFFFAOYSA-M Sodium bicarbonate Chemical compound [Na+].OC([O-])=O UIIMBOGNXHQVGW-UHFFFAOYSA-M 0.000 description 6
- 238000009792 diffusion process Methods 0.000 description 6
- XHXFXVLFKHQFAL-UHFFFAOYSA-N phosphoryl trichloride Chemical compound ClP(Cl)(Cl)=O XHXFXVLFKHQFAL-UHFFFAOYSA-N 0.000 description 6
- 238000001179 sorption measurement Methods 0.000 description 6
- MZLGASXMSKOWSE-UHFFFAOYSA-N tantalum nitride Chemical compound [Ta]#N MZLGASXMSKOWSE-UHFFFAOYSA-N 0.000 description 6
- 229910052732 germanium Inorganic materials 0.000 description 5
- GNPVGFCGXDBREM-UHFFFAOYSA-N germanium atom Chemical compound [Ge] GNPVGFCGXDBREM-UHFFFAOYSA-N 0.000 description 5
- 238000012545 processing Methods 0.000 description 5
- 238000005215 recombination Methods 0.000 description 5
- 230000006798 recombination Effects 0.000 description 5
- KRHYYFGTRYWZRS-UHFFFAOYSA-N Fluorane Chemical compound F KRHYYFGTRYWZRS-UHFFFAOYSA-N 0.000 description 4
- KJTLSVCANCCWHF-UHFFFAOYSA-N Ruthenium Chemical compound [Ru] KJTLSVCANCCWHF-UHFFFAOYSA-N 0.000 description 4
- 229910052709 silver Inorganic materials 0.000 description 4
- XOLBLPGZBRYERU-UHFFFAOYSA-N tin dioxide Chemical compound O=[Sn]=O XOLBLPGZBRYERU-UHFFFAOYSA-N 0.000 description 4
- ZOXJGFHDIHLPTG-UHFFFAOYSA-N Boron Chemical compound [B] ZOXJGFHDIHLPTG-UHFFFAOYSA-N 0.000 description 3
- GWEVSGVZZGPLCZ-UHFFFAOYSA-N Titan oxide Chemical compound O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 description 3
- 229910052782 aluminium Inorganic materials 0.000 description 3
- 229910052796 boron Inorganic materials 0.000 description 3
- 239000007772 electrode material Substances 0.000 description 3
- 239000011521 glass Substances 0.000 description 3
- 238000007654 immersion Methods 0.000 description 3
- 238000005268 plasma chemical vapour deposition Methods 0.000 description 3
- 238000005498 polishing Methods 0.000 description 3
- 229910052707 ruthenium Inorganic materials 0.000 description 3
- 229910001925 ruthenium oxide Inorganic materials 0.000 description 3
- WOCIAKWEIIZHES-UHFFFAOYSA-N ruthenium(iv) oxide Chemical compound O=[Ru]=O WOCIAKWEIIZHES-UHFFFAOYSA-N 0.000 description 3
- 239000004332 silver Substances 0.000 description 3
- 229910000030 sodium bicarbonate Inorganic materials 0.000 description 3
- 235000017557 sodium bicarbonate Nutrition 0.000 description 3
- 239000000243 solution Substances 0.000 description 3
- GYHNNYVSQQEPJS-UHFFFAOYSA-N Gallium Chemical compound [Ga] GYHNNYVSQQEPJS-UHFFFAOYSA-N 0.000 description 2
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 description 2
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 2
- 239000006061 abrasive grain Substances 0.000 description 2
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical group [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 2
- 238000005229 chemical vapour deposition Methods 0.000 description 2
- 239000000356 contaminant Substances 0.000 description 2
- 230000007547 defect Effects 0.000 description 2
- 229910052733 gallium Inorganic materials 0.000 description 2
- 239000007789 gas Substances 0.000 description 2
- 238000005247 gettering Methods 0.000 description 2
- 238000010438 heat treatment Methods 0.000 description 2
- QOSATHPSBFQAML-UHFFFAOYSA-N hydrogen peroxide;hydrate Chemical compound O.OO QOSATHPSBFQAML-UHFFFAOYSA-N 0.000 description 2
- 239000012535 impurity Substances 0.000 description 2
- 238000009413 insulation Methods 0.000 description 2
- 229960004592 isopropanol Drugs 0.000 description 2
- 239000007788 liquid Substances 0.000 description 2
- ORUIBWPALBXDOA-UHFFFAOYSA-L magnesium fluoride Chemical compound [F-].[F-].[Mg+2] ORUIBWPALBXDOA-UHFFFAOYSA-L 0.000 description 2
- 229910001635 magnesium fluoride Inorganic materials 0.000 description 2
- 229910052751 metal Inorganic materials 0.000 description 2
- 239000002184 metal Substances 0.000 description 2
- TWNQGVIAIRXVLR-UHFFFAOYSA-N oxo(oxoalumanyloxy)alumane Chemical compound O=[Al]O[Al]=O TWNQGVIAIRXVLR-UHFFFAOYSA-N 0.000 description 2
- 230000002093 peripheral effect Effects 0.000 description 2
- 239000012071 phase Substances 0.000 description 2
- 229910052698 phosphorus Inorganic materials 0.000 description 2
- 239000011574 phosphorus Substances 0.000 description 2
- 238000005240 physical vapour deposition Methods 0.000 description 2
- 238000007639 printing Methods 0.000 description 2
- 238000007650 screen-printing Methods 0.000 description 2
- 238000004544 sputter deposition Methods 0.000 description 2
- 229910052715 tantalum Inorganic materials 0.000 description 2
- GUVRBAGPIYLISA-UHFFFAOYSA-N tantalum atom Chemical compound [Ta] GUVRBAGPIYLISA-UHFFFAOYSA-N 0.000 description 2
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 description 1
- 230000002378 acidificating effect Effects 0.000 description 1
- 239000012670 alkaline solution Substances 0.000 description 1
- 229910052785 arsenic Inorganic materials 0.000 description 1
- RQNWIZPPADIBDY-UHFFFAOYSA-N arsenic atom Chemical compound [As] RQNWIZPPADIBDY-UHFFFAOYSA-N 0.000 description 1
- CFJRGWXELQQLSA-UHFFFAOYSA-N azanylidyneniobium Chemical compound [Nb]#N CFJRGWXELQQLSA-UHFFFAOYSA-N 0.000 description 1
- 239000011230 binding agent Substances 0.000 description 1
- 229910052797 bismuth Inorganic materials 0.000 description 1
- JCXGWMGPZLAOME-UHFFFAOYSA-N bismuth atom Chemical compound [Bi] JCXGWMGPZLAOME-UHFFFAOYSA-N 0.000 description 1
- 229910000420 cerium oxide Inorganic materials 0.000 description 1
- 230000000052 comparative effect Effects 0.000 description 1
- 239000000470 constituent Substances 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 229910052802 copper Inorganic materials 0.000 description 1
- 239000010949 copper Substances 0.000 description 1
- 238000000151 deposition Methods 0.000 description 1
- 230000008021 deposition Effects 0.000 description 1
- 239000002019 doping agent Substances 0.000 description 1
- 238000011156 evaluation Methods 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 238000007667 floating Methods 0.000 description 1
- 238000000227 grinding Methods 0.000 description 1
- 229910021478 group 5 element Inorganic materials 0.000 description 1
- 229910000449 hafnium oxide Inorganic materials 0.000 description 1
- WIHZLLGSGQNAGK-UHFFFAOYSA-N hafnium(4+);oxygen(2-) Chemical compound [O-2].[O-2].[Hf+4] WIHZLLGSGQNAGK-UHFFFAOYSA-N 0.000 description 1
- 229910001385 heavy metal Inorganic materials 0.000 description 1
- 238000011835 investigation Methods 0.000 description 1
- 238000000608 laser ablation Methods 0.000 description 1
- 238000003754 machining Methods 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 238000002156 mixing Methods 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 229910017604 nitric acid Inorganic materials 0.000 description 1
- BMMGVYCKOGBVEV-UHFFFAOYSA-N oxo(oxoceriooxy)cerium Chemical compound [Ce]=O.O=[Ce]=O BMMGVYCKOGBVEV-UHFFFAOYSA-N 0.000 description 1
- 230000000149 penetrating effect Effects 0.000 description 1
- 230000000737 periodic effect Effects 0.000 description 1
- 238000000206 photolithography Methods 0.000 description 1
- 238000007747 plating Methods 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 239000004065 semiconductor Substances 0.000 description 1
- 239000002002 slurry Substances 0.000 description 1
- 239000004094 surface-active agent Substances 0.000 description 1
- 239000004408 titanium dioxide Substances 0.000 description 1
- OGIDPMRJRNCKJF-UHFFFAOYSA-N titanium oxide Inorganic materials [Ti]=O OGIDPMRJRNCKJF-UHFFFAOYSA-N 0.000 description 1
- 238000001771 vacuum deposition Methods 0.000 description 1
- 238000007740 vapor deposition Methods 0.000 description 1
- 239000012808 vapor phase Substances 0.000 description 1
- 238000004857 zone melting Methods 0.000 description 1
Classifications
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
- H01L31/02—Details
- H01L31/0236—Special surface textures
- H01L31/02363—Special surface textures of the semiconductor body itself, e.g. textured active layers
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
- H01L31/0248—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by their semiconductor bodies
- H01L31/036—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by their semiconductor bodies characterised by their crystalline structure or particular orientation of the crystalline planes
- H01L31/0392—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by their semiconductor bodies characterised by their crystalline structure or particular orientation of the crystalline planes including thin films deposited on metallic or insulating substrates ; characterised by specific substrate materials or substrate features or by the presence of intermediate layers, e.g. barrier layers, on the substrate
- H01L31/03921—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by their semiconductor bodies characterised by their crystalline structure or particular orientation of the crystalline planes including thin films deposited on metallic or insulating substrates ; characterised by specific substrate materials or substrate features or by the presence of intermediate layers, e.g. barrier layers, on the substrate including only elements of Group IV of the Periodic Table
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- H01—ELECTRIC ELEMENTS
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- H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
- H01L31/04—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof adapted as photovoltaic [PV] conversion devices
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- H—ELECTRICITY
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- H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
- H01L31/04—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof adapted as photovoltaic [PV] conversion devices
- H01L31/06—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof adapted as photovoltaic [PV] conversion devices characterised by potential barriers
- H01L31/068—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof adapted as photovoltaic [PV] conversion devices characterised by potential barriers the potential barriers being only of the PN homojunction type, e.g. bulk silicon PN homojunction solar cells or thin film polycrystalline silicon PN homojunction solar cells
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Description
本發明係關於太陽能電池及其製造方法。
太陽能電池係為將光能轉換為電力的半導體元件,其中尤以矽單結晶系太陽能電池,轉換效率高、且能夠比較容易地製造,故成為一般所普及之太陽能電池的主力。矽單結晶系太陽能電池中,例如於日本特開平9-129907號公報(專利文獻1)及日本特開平10-7493號公報(專利文獻2)中所揭示,係以防止反射損失為目的,而進行在表面形成有稱為紋理的微細突起。太陽能電池之表面為平坦的情況時,入射之光的一部分會被反射,而無法轉換為電流。但是,藉由此紋理構造,會帶來複數次的使反射光之一部分再入射於太陽能電池的機會。結果,太陽能電池之受光面的反射率降低,因此短路電流提高,太陽能電池之性能會大幅提升。
如上所述之紋理構造,如專利文獻1及專利文獻2所揭示者,係藉由對矽單結晶基板進行異向性蝕刻而形成。異向性蝕刻,係指利用矽之面方位的蝕刻速度差者。具體而言,製造矽單結晶基板時之切片時,將來自藉由線鋸等而產生之切片加工履歷的損傷層蝕刻之後,再度藉由浸漬於加熱之氫氧化鈉、氫氧化鉀、碳酸鉀、碳酸鈉、碳酸氫鈉等鹼性水溶液中來實施。再者,亦常有使指定量的2-
丙醇溶解於上述鹼性水溶液中,以促進反應。
現在,太陽能電池所被強力要求的,是伴隨著光電轉換效率之高效率化及太陽能電池製造步驟之簡化而達到低成本化。於上述損傷蝕刻後之基板表面,會有切片時之漿料、線鋸之研磨粒等微量殘存的情況,即使將該等污染物質以界面活性劑等洗淨去除,亦極難排除微量混入。
又,其他亦有p-n接合形成步驟、抗反射膜形成步驟、表背面電極形成步驟等之重金屬等污染物質對基板的附著,即使以例如鹽酸與過氧化氫水混合之水溶液實施洗淨,亦難以完全去除,該等會降低體生命期,而妨礙太陽能電池之高效率化。
再者,以往,如日本特開2005-209726號公報(專利文獻3)所記載,將於藉由矽單結晶鑄錠之切片而得的矽單結晶基板之第一主表面側形成之切片時的一次損傷層予以機械性或化學性去除,另一方面,已知有藉由導入來自與前述切片不同的機械的加工履歷所造成之新的損傷,以形成較一次損傷層更薄之二次損傷層,並藉由將該二次損傷層實施異向性蝕刻,以形成紋理構造,且於該紋理構造上形成受光面側電極的太陽能電池之製造方法。
[專利文獻1]日本特開平9-129907號公報
[專利文獻2]日本特開平10-7493號公報
[專利文獻3]日本特開2005-209726號公報
因而,本發明之課題為提供在不增加工時之下,能夠極有效率地,藉由具有優良體生命期之高品質,來更提高轉換效率的太陽能電池及其製造方法。
本發明者等人,為達成上述目的而進行戮力探討的結果,發現了:不將於藉由矽單結晶鑄錠之切片而得之矽單結晶基板表面形成之切片時的損傷層完全予以化學性去除,而使紋理形成後亦於基板含有較佳為0.2~5μm之該損傷層是有效的。亦即,以往認為不將來自該矽單結晶基板製造時之切片加工履歷的損傷層完全去除時,會產生表面再結合速度會增大、太陽能電池特性降低之缺點,因此,紋理形成係於將切片時所產生之損傷層以鹼性水溶液去除之後來進行。此情況下,切片時產生之加工損傷層係為10μm以上而較厚,至大致完全去除該損傷層為止,會施以深度的化學蝕刻。依照本發明者等戮力研究的結果,意外地,可知不完全去除來自切片加工履歷之損傷層,而於基板刻意殘留0.2~5μm之損傷層,吸附(gettering)效果會增大、改善體生命期、太陽能電池之電池特性會提高。
再者,上述專利文獻3中亦揭示於紋理形成前形成損傷層,此係來自與藉由切片之損傷不同之機械的加工履歷,而導入新的損傷,藉以形成比一次損傷層更薄之二次損傷層,藉由對該二次損傷層實施異向性蝕刻,來形成紋理構造,且於該紋理構造上形成受光面側電極者,其係將來自切片加工履歷之損傷層完全蝕刻去除後,重新設置別的損傷層者,故相當費時費力,並且亦必須注意控制二次損傷層的厚度。相對於此,本發明中之紋理形成後殘留的損傷層係原本切片加工時之物,因此不需額外形成損傷層,如上所述,係僅殘留下少許在以往為了使表面再結合速度降低而必須去除之切片加工時的損傷層,即可改善體生命期者。
因此,本發明係提供下述之太陽能電池及其製造方法。
申請專利範圍第1項:
一種太陽能電池,其係於矽單結晶基板表面具有紋理構造之太陽能電池,其特徵為:該基板之表面附近係具有來自製造矽單結晶基板時之切片加工履歷的損傷層。
申請專利範圍第2項:
如申請專利範圍第1項之太陽能電池,其中前述損傷層之深度為0.2~5μm。
申請專利範圍第3項:
如申請專利範圍第1或2項之太陽能電池,其中前述矽單結晶基板,係以{100}面為主表面。
申請專利範圍第4項:
一種太陽能電池之製造方法,其特徵為:對於表面具有來自製造矽單結晶基板時之切片加工履歷的損傷層之矽單結晶基板,包含有藉由化學蝕刻來形成紋理的步驟、形成p-n接合的步驟、與形成電極的步驟,且係使來自製造前述矽單結晶基板時之切片加工履歷的損傷層殘留而於形成紋理後的基板表面附近,以存在有該損傷層的方式,來進行紋理的形成。
申請專利範圍第5項:
如申請專利範圍第4項之太陽能電池之製造方法,其係以前述紋理形成後之損傷深度為0.2~5μm的方式來形成紋理。
申請專利範圍第6項:
如申請專利範圍第4或5項之太陽能電池之製造方法,其中前述矽單結晶基板之主表面為{100}面,且藉由使用鹼性水溶液作異向性蝕刻以進行前述化學蝕刻,使前述紋理構造形成為4個被{111}面包圍之正四角紡錘形突起之集合體。
申請專利範圍第7項:
如申請專利範圍第4至6項中任一項之太陽能電池之製造方法,其中化學蝕刻前述矽單結晶基板的表面之鹼性水溶液,為含有氫氧化鈉、氫氧化鉀、碳酸鉀、碳酸鈉、碳酸氫鈉之任一者的水溶液。
依照本發明之太陽能電池之製造方法,被導入於殘存於紋理上之損傷層的結晶缺陷係發揮作為雜質原子之吸附位置(gettering site)的功能,因此有助於少數載子生命期(體生命期)變長,與轉換效率的提高。
再者,所形成的損傷層深度係期望為0.2~5μm。超過5μm時,損傷層會成為表面再結合速度增大之原因,而導致太陽能電池之特性降低。又,損傷層深度低於0.2μm時,吸附效果可能會不充分。
矽單結晶基板能夠使{100}面為主表面。此外,藉由使用鹼性水溶液來進行異向性蝕刻,能夠高效率地將紋理構造形成為4個被{111}面圍繞的正四角紡錘形突起之集合體,且抗反射效果亦良好。
損傷層能夠使用來自切片加工履歷者。此時,不需要重新賦予損傷,故不增加工時。
再者,所謂損傷層,係指矽結晶雖為理論上之正確矽原子配列,但藉由切片加工之線鋸等而所產生含多數差排缺陷或破裂、切屑之層。
依照本發明,來自製造在矽單結晶基板表面附近存在的基板時之切片加工履歷的損傷層,係發揮作為吸附位置的功能,有助於基板之少數載子的生命期提高。藉由此效果,太陽能電池特性會飛躍地提高。又,因為不是重新賦予損傷,而係利用切片之損傷,故不會增加工時。
以下,對本發明之太陽能電池構造,一面參照圖式同時進行說明。惟本發明並非限於具有此構造之太陽能電池。
圖1當中,太陽能電池100係於例如以硼為摻雜物的p型矽單結晶基板(以下,亦單純稱「基板」)1之第一主表面側(受光面側),形成n型射極層42,且於基板面內方向形成有p-n接合部48。p-n接合之形成,可為對p型矽形成n型層之構造、或亦可相反地為對n型矽基板形成p型層之構造。因為構造上並無差異,因此以下對p型基板作敘述。
受光面側電極5係形成於射極層42之主表面。射極層42係形成太陽能電池之受光面,因此為了提高光對p-n接合部48之入射效率,受光面側電極5能夠構成為具有:以Al或Ag等為了降低內部電阻而以適當間隔形成之粗的母線電極、與由該母線電極以指定間隔分支為梳子型之指狀電極者。此外,射極層42之受光面側電極5的非形成區域,係被受光面側絕緣膜43所覆蓋。另一方面,基板1之第二主表面(背面),係以背面側絕緣膜46覆蓋而成,且該背面側絕緣膜46之整面係以Al等所構成的背面電極4來覆蓋。該背面電極4,係透過貫通該背面側絕緣膜46之通電部(接觸孔)46h而與基板1之背面導通而成。再者,圖中47為抗反射膜(SiNx
膜)。
再者,基板1之構成材料的矽單結晶,在波長400~1,100nm之區域有6.00~3.50之大折射率,因此太陽光線入射後的反射損失會成為問題。因而,於基板1表面,係如圖2所示地形成外面為由{111}面之多數的四角紡錘形突起所構成的紋理構造。
以下,使用圖3來說明本發明之太陽能電池之製造方法。但本發明並不受此方法所製造之太陽能電池所限制。
由摻雜硼或鎵等III族元素,且比電阻為0.1~5Ω‧cm之矽單結晶,藉由外周鋒鋸、內周鋒鋸、帶鋸、多帶鋸、多線鋸等線鋸切片,以切出主表面{100}面之p型矽單結晶基板1[圖3(A):步驟1]。
矽單結晶可使用摻雜硼或鎵等III族元素之p型矽單結晶、亦可使用摻雜磷或砷等V族元素之n型矽單結晶。
本說明書中雖針對p型基板的情況敘述,但n型基板的情況,只要將形成射極層時之n與p對調來考慮即可。
單結晶矽基板,可使用FZ(Floating Zone Melting)法及CZ(Czochralski)法之任一者來製造,但由機械強度的觀點而言,以CZ法來製造較佳。
藉由此切片,於基板1之兩主表面係形成深度超過10μm之損傷層2。
接著進入步驟2,進行損傷層2之去除及紋理構造3之形成[圖3(B)]。損傷層2之去除及紋理構造3之形成,係於加熱後之氫氧化鈉、氫氧化鉀、碳酸鉀、碳酸鈉、碳酸氫鈉等鹼性水溶液(濃度0.1~20質量%、溫度60~100℃)中將基板1浸漬10~30分鐘左右,藉由異向性蝕刻基板表面來進行。另外,於上述溶液中溶解適量的2-丙醇時,能夠促進蝕刻反應。
此時,刻意不完全地去除損傷層,而於基板殘留0.2~5μm左右的損傷層。殘留的損傷層之深度,係能夠以對蝕刻液之浸漬時間及蝕刻液之溫度而來控制。
損傷層深度係藉由將基板表面傾斜5°左右而研磨(傾斜研磨,angle polish),而能夠以顯微鏡或掃描型電子顯微鏡(SEM)觀察。又,將以研磨粒作表面研磨後之矽基板以階段性之化學蝕刻來去除,藉由以X射線拓樸學評估,能夠推測損傷層之密度及深度。藉由該等之方法,於受光面形成含有深度0.2~5μm之微細損傷層2的紋理構造3。
此損傷層2係發揮作為吸附位置的功能,以該吸附將雜質濃縮於損傷層2,藉以能夠提高基板1之少數載子生命期(體生命期),且有助於太陽能電池之轉換效率的提高。特別是,使用太陽能電池等級之矽基板時,生命期會顯著提高。
損傷深度太淺時,可能無法展現上述效果;又,太深時,損傷層可能會造成表面再結合速度增大,且可能導致太陽能電池特性的降低。
紋理構造形成後之基板1,係於由鹽酸、硫酸、硝酸、氫氟酸或該等之混合液所構成之酸性水溶液中洗淨。由經濟及效率的見解而言,較佳為於鹽酸中洗淨。為了提高洗淨度,亦可於鹽酸溶液中混合1質量%以上、5質量%以下之過氧化氫水,加熱至60℃以上、90℃以下來洗淨。
於該基板1之受光面上,藉由使用了氧氯化磷之氣相擴散法來形成射極層42(圖1)。為了防止對第二主表面(以下、稱為背面)的擴散,係將背面彼此疊合,而以2枚一組並排於擴散舟以進行氣相擴散為佳。具體而言,係在氧氯化磷環境中,以820~880℃熱處理數十分鐘,於受光面形成n型層。形成後之射極層深度較佳為0.2μm以上、0.5μm以下,薄片電阻較佳為40Ω/□以上、150Ω/□以下。之後,藉由擴散反應,將形成於基板1之第一主表面上的磷玻璃,浸漬於2質量%以上、5質量%以下之氫氟酸中數分鐘而去除。
另外,使用了n型基板時,能夠藉由例如於900~1,000℃將BBr3
氣相擴散數十分鐘,藉以形成p型射極層。
接著,如步驟3所示,於基板1之第二主表面形成以氮化矽為首之由氧化矽、氮化矽、氧化鈰、氧化鋁、二氧化錫、二氧化鈦、氟化鎂、氧化鉭等所構成的背面側絕緣膜46(圖1:圖3中省略圖示)。例如係使用電漿CVD裝置將氮化矽膜製膜為85~105nm左右。然後,將接觸孔46h(圖1:圖3中省略圖示)藉由光微影術、機械研磨、或雷射剝蝕等方法開口之後,進一步將背面電極4形成為0.5μm以上、5μm以下的厚度[圖3(C)]。電極材料雖使用銀或銅等金屬,但就經濟性、加工性、與矽之接觸性的觀點來看最佳為鋁。就金屬之堆積而言,濺鍍法、真空蒸鍍法、網版印刷法等任意方法均可。
之後,如步驟4所示,於基板1之第一主表面進行受光面側絕緣膜43(圖1:圖3中省略圖示)及受光面側電極5的形成[圖3(D)]。受光面側絕緣膜43係兼有抗反射膜的角色,可以由氧化矽、氮化矽、氧化鈰、氧化鋁、二氧化錫、二氧化鈦、氟化鎂、氧化鉭等構成。又,亦可使該等為2種以上組合之層合構造。受光面側絕緣膜43,以PVD(Physical Vapor Deposition:濺鍍等)法或CVD(Chemical Vapor Deposition)法之任意方法均能夠形成,為了製造高轉換效率之太陽能電池,以遠距電漿CVD法形成氮化矽者,能夠達成小的表面再結合速度,故較佳。又,受光面側電極5能夠以蒸鍍法、濺鍍法、鍍敷法、印刷法等來製造。雖可用任意之方法,但為了低成本且高通量,較佳為印刷法。將銀粉末與玻璃料與有機物黏結劑混合後的銀膏網版印刷後,藉由熱處理使銀粉末貫通氮化矽膜(燒穿),使得受光面側電極5與射極層42導通。此外,受光面及背面之處理順序即使相反,亦不會有問題。
以下,顯示實施例與比較例,對本發明具體地說明,但本發明不受下述之實施例所限制。
以下,針對為了確認本發明之效果而進行之實驗結果來說明。
首先,準備厚200μm之摻雜B之p型矽基板(主表面{100}面、切片後),使基板浸漬於加熱為82℃之2.2質量%的氫氧化鈉水溶液中,藉由異向性蝕刻而進行紋理層的形成。此時,將基板蝕刻7μm左右(浸漬13分鐘),製造殘留有損傷層者10枚、以及蝕刻12μm左右(浸漬30分鐘),製造損傷層完全去除者10枚。
接著,對該等基板,在氧氯化磷環境下於850℃熱處理,以形成射極層。於表1顯示測定起始時與射極層形成後該等基板之體生命期的結果。不管是起始時、還是熱擴散步驟後,殘留損傷層之蝕刻7μm左右的基板,相較於完全去除損傷層之蝕刻12μm左右的基板,均顯示較高的體生命期值。此係來自殘留之損傷層之吸附的效果。
之後、使用電漿CVD法來形成氮化矽膜,且藉由網版印刷法形成由指狀電極及母線電極所構成的受光面側電極與背面電極,藉以製造太陽能電池。另外,受光面電極材料係使用銀粉末與玻璃料混合之銀膏、背面電極材料係使用鋁膏。然後使用太陽模擬器,在標準條件下(照射強度:100mW/cm2
、AM:1.5、溫度25℃)測定該等太陽能電池之電流/電壓特性,求出轉換效率。結果示於表2。殘留損傷層之蝕刻7μm左右的基板,其短路電流與開路電壓,相較於完全去除損傷層之蝕刻12μm左右之基板,均顯示出較高值。此係來自損傷層之吸附效果的效果。可知藉由本發明之方法,能夠製造高效率之太陽能電池。
1...基板
2...損傷層
3...紋理構造
4...背面電極
5...受光面側電極
42...射極層
43...受光面側絕緣膜
46...背面側絕緣膜
46h...通電部(接觸孔)
47...抗反射膜
48...p-n接合部
100...太陽能電池
圖1為示意本發明之製造方法的對象之太陽能電池的一實施例的剖面圖。
圖2為形成於基板表面之紋理構造的立體圖。
圖3為依序說明本發明之太陽能電池製造方法之概要之說明圖。
Claims (6)
- 一種太陽能電池,其係於矽單結晶基板表面具有紋理構造之太陽能電池,其特徵為:該基板之表面附近係具有來自製造矽單結晶基板時之切片加工履歷的損傷層。
- 如申請專利範圍第1項之太陽能電池,其中前述損傷層之深度為0.2~5μm。
- 一種太陽能電池之製造方法,其特徵為:對於表面具有來自製造矽單結晶基板時之切片加工履歷的損傷層之矽單結晶基板,包含有藉由化學蝕刻來形成紋理的步驟、形成p-n接合的步驟、與形成電極的步驟,且係使來自製造前述矽單結晶基板時之切片加工履歷的損傷層殘留而於形成紋理後的基板表面附近,以存在有該損傷層的方式,來進行紋理的形成。
- 如申請專利範圍第3項之太陽能電池之製造方法,其係以前述紋理形成後之損傷深度為0.2~5μm的方式來形成紋理。
- 如申請專利範圍第3或4項之太陽能電池之製造方法,其中前述矽單結晶基板之主表面為{100}面,且藉由使用鹼性水溶液作異向性蝕刻以進行前述化學蝕刻,使前述紋理構造形成為4個被{111}面包圍之正四角紡錘形突起之集合體。
- 如申請專利範圍第3或4項之太陽能電池之製造方法,其中化學蝕刻前述矽單結晶基板的表面之鹼性水溶液,為含有氫氧化鈉、氫氧化鉀、碳酸鉀、碳酸鈉、碳酸 氫鈉之任一者的水溶液。
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JP5938113B1 (ja) | 2015-01-05 | 2016-06-22 | 信越化学工業株式会社 | 太陽電池用基板の製造方法 |
CN107431099B (zh) * | 2015-03-24 | 2019-09-03 | 株式会社钟化 | 太阳能电池用结晶硅基板的制造方法、结晶硅系太阳能电池的制造方法及结晶硅系太阳能电池模块的制造方法 |
KR101939482B1 (ko) * | 2016-07-28 | 2019-01-17 | 한양대학교 에리카산학협력단 | 실리콘 태양전지, 및 그 제조 방법 |
CN117157771A (zh) * | 2021-03-30 | 2023-12-01 | 株式会社钟化 | 太阳能电池以及太阳能电池的制造方法 |
CN114883450B (zh) * | 2022-05-21 | 2023-06-27 | 一道新能源科技(衢州)有限公司 | 一种perc电池的制绒工艺 |
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JP2002076388A (ja) * | 2000-08-30 | 2002-03-15 | Shin Etsu Handotai Co Ltd | 太陽電池セルの製造方法 |
TW200303620A (en) * | 2002-02-28 | 2003-09-01 | Shinetsu Handotai Kk | Solar cell module and its manufacturing method |
JP2005209726A (ja) * | 2004-01-20 | 2005-08-04 | Shin Etsu Handotai Co Ltd | 太陽電池の製造方法 |
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JP5527417B2 (ja) | 2014-06-18 |
JPWO2012036002A1 (ja) | 2014-02-03 |
KR20130113454A (ko) | 2013-10-15 |
EP2618382B1 (en) | 2021-05-05 |
WO2012036002A1 (ja) | 2012-03-22 |
AU2011304166A1 (en) | 2013-04-04 |
US20130247974A1 (en) | 2013-09-26 |
SG188972A1 (en) | 2013-05-31 |
US9018520B2 (en) | 2015-04-28 |
KR101659451B1 (ko) | 2016-09-23 |
CN103201847A (zh) | 2013-07-10 |
EP2618382A1 (en) | 2013-07-24 |
CN103201847B (zh) | 2016-03-16 |
MY159228A (en) | 2016-12-30 |
AU2011304166B2 (en) | 2015-03-05 |
EP2618382A4 (en) | 2017-04-05 |
TW201232793A (en) | 2012-08-01 |
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