201222851 六、發明說明： 【發明所屬之技術領域】 [0001] 本案係關於一種光電元件之製造方法，尤指—種利 用熱氧化層作為保護層以及擴散之屏障而形成選擇性射 極，以及結合背面局部接觸配合熱氧化層之結構的低成 本雙面太陽能電池之製造方法。 【先前技術】 [0002]201222851 VI. Description of the Invention: [Technical Field of the Invention] [0001] The present invention relates to a method for manufacturing a photovoltaic element, and more particularly to a selective emitter using a thermal oxide layer as a protective layer and a diffusion barrier, and a combination A method of manufacturing a low-cost double-sided solar cell in which the back surface is partially contacted with a structure of a thermal oxide layer. [Prior Art] [0002]
由於全球能源的持續短缺以及近年來環保旁/戠、豕漸 抬頭，因此目前相關產業最關心的議題莫過於如何=供 環保、乾淨又不失效能的能源。在各種替代性的能源中 ’利用太陽光經由光電能量之轉換而產生電能的太陽能 電池Cell)，是目前所廣泛應用且積極研發之技 術。隨著相關產業持續投入研發太陽能電池，不但使太 陽能電池的技術不斷精進、提昇，更開發出了雙面太陽 能電池（Bifacial S〇lar Cell) ’藉由雙面受光的設計 ’使太陽能電池的兩個表面皆可接收光線，並將太陽能 轉換為電能’進而可更有效率地提昇雙面太陽能電池所 能提供之能量。 [0003] 請參閱第一圖A_E ’其係為習用雙面單晶或多晶石夕 (Single- or Multi-crystalline SiDue to the continuous shortage of global energy sources and the rising environmental protection in recent years, the most concerned issue in the relevant industries is how to provide energy for environmental protection, cleanliness and non-failure. Among various alternative energy sources, a solar cell Cell that uses solar energy to generate electric energy through conversion of photovoltaic energy is a technology that is widely used and actively developed. As the related industries continue to invest in the research and development of solar cells, not only have the technology of solar cells been continuously improved and improved, but also the development of two-sided solar cells (Bifacial S〇lar Cell) Both surfaces can receive light and convert solar energy into electrical energy', which in turn can more efficiently increase the energy available from double-sided solar cells. [0003] Please refer to the first figure A_E ' which is a conventional double-sided single crystal or polycrystalline silicon (Single- or Multi-crystalline Si)
Si)之太陽能電池製造流程結構示意圖。如第一圖A所示 ，首先，提供P型半導體基板10，並將P型半導體基板1〇 的表面形成凹凸的紋理（Texturing)，以減低光線的 反射率，其中由於凹凸的紋理相當細微，因此在第一圖八 中省略繪示。接著，提供摻雜劑及利用熱擴散的方式在 099139446 表單編號A0101 第3頁/共22頁 0992068733-0 201222851 第一表面S1形成由N +型半導體所構成的射極層I!( Emitter layer) ’且在P型半導體基板1〇與射極層11 之間形成pn接面（pn junction)。此時，在射極層11上 亦會形成填石夕玻璃層12 (Phosphorous silicate glass，PSG)，如第一圖B所示。之後，利用蝕刻的方 式將表面的磷矽玻璃層12移除，如第一圖C所示。 [0004] [0005] 接著’再如第一圖D所示’使用沉積（Deposit ion) 的方式於射極層12上形成一層由氮矽化合物（SiNx)構 成的第一抗反射膜 13 (Anti-reflection coating， ARC)，以降低光線的反射率並保護射極層u。其後，如 第一圖E所示，同樣於第二表面S2上以三溴化硼（BBr )做 3 為擴散源進行摻雜，形成背表面電場層14(Back surface field ， BSF) ， 並再沉積一層 由氮矽化合物構成的 第二抗反射膜15，之後，再使用網版印刷（Screen Printing)技術將鋁導電材料印刷在第二表面以上，且 以同樣的方式將銀導電材料印刷在第一表面81上。最後 ，進行燒結（Firing)步驟，使第一表面S1產生第一電極 16，以及第二表面S2產生第二電極17，藉此以完成太陽 能電池之製造。 然而，在此傳統雙面太陽能電池的製造過程中，主 要是以提供雜劑及利用熱擴散的方式於第一表面31形 成由N +型半導體所構成的射極層u並形成pn接面，在此 製程中調整射極濃度為重摻雜雖然可以降低電池之接觸 電阻但卻使的表面再結合速率增加而調整射極濃度為 輕摻雜則可減少表面再結合速率，但卻會提高電池的接 099139446 表單編號A0101 第4頁/共22頁 0992068733-0 201222851 電陡，因此在調整射極層濃度上皆無法使表面再結合 迷率與電池接觸電阻的改善可以兩全其美，另外在第二 兩S 2係以擴散方式形成背表面電場層，因此習用上述 t種則會因熱擴散過程的製程熱預算（the〇iai buket)過多與參數控制不易而導致製程精度降低，連帶 地増加不少物料以及時間成本。 [0006] Ο 再者，習用技術於使用網版印刷技術將導電材料印 於第二表面S2時，係於第二表面S2之整面印刷導電材 料’會因為金屬的特性導致表面再結合速率較高以及使 3曰圓彎曲（wafer bowing) ’造成製程不穩定之現象，使 雙面太陽能電池之光電轉換效率較差’影響製程之品質 [0007] 【發明内 容】 ❹ 方法觸電轉換缺點 本案之主要目的為提供一種雙面太陽能電池之製造 ，俾解決習用雙面太陽能電池之製造過程中，因接 P且與表面再結合速率較高而影響太陽能電池之光電 欵率，以及製程繁複而造成時間、物料成本増加等 [0008] 本案之另一目的為提供一種雙面太陽能電池之製、A 方法，利用熱氧化層作為保護層以及擴散過程中的屏障 而形成選擇性射極，以及使用背表面局部接觸結構配人 背表面氧化層的鈍化效果取代背面整面的表 以、去 叫电場層， 建到降低表面再結合速率，提升雙面太陽能電池之光 電轉換效率，以及簡化製程步驟並降低時間與物料成本 之功效。 099139446 表單編號A0101 第5頁/共22頁 0992068733-0 201222851 [0009] 為達上述目的，本案之一較廣實施態樣為提供一種 雙面太陽能電池之製造方法，至少包括步驟：（a)提供 半導體基板；（b)同時形成第一熱氧化層於半導體基板之 第一表面以及形成第二熱氧化層於半導體基板之第二表 面；（c)形成第二抗反射膜於第二熱氧化層；（d)移除部 分之第一熱氧化層，且以第一熱氧化層為遮罩於半導體 基板之至少部分區域，在一次擴散的製程步驟中使其同 時有濃、淡不同區域的摻雜濃度形成出選擇性射極，其 中半導體基板與射極間形成一pn接面；（e)形成第一抗反 射膜於第一表面；（f)形成至少一第二電極於第二表面； 以及（g)形成至少一第一電極於第一表面。 [0010] 為達上述目的，本案之另一較廣實施態樣為提供一 種雙面太陽能電池之製造方法，至少包括步驟：（a)提供 半導體基板；（b)形成第一熱氧化層於半導體基板之第一 表面以及形成第二熱氧化層於半導體基板之第二表面； (c)形成第二抗反射膜於第二熱氧化層；（d)於半導體基 板之至少部分區域形成選擇性射極，其中半導體基板與 射極間形成一pn接面；（e)形成第一抗反射膜於第一表面 ;(f)形成至少一第二電極於第二表面之部分區域；以及 (g)形成至少一第一電極於第一表面。 【實施方式】 [0011] 體現本案特徵與優點的一些典型實施例將在後段的 說明中詳細敘述。應理解的是本案能夠在不同的態樣上 具有各種的變化，其皆不脫離本案的範圍，且其中的說 明及圖示在本質上係當作說明之用，而非用以限制本案 099139446 表單編號A0101 第6頁/共22頁 0992068733-0 201222851 [0012]Schematic diagram of the structure of the solar cell manufacturing process of Si). As shown in FIG. A, first, a P-type semiconductor substrate 10 is provided, and a surface of a P-type semiconductor substrate 1 is formed with a textured texture to reduce the reflectance of light, wherein the texture of the unevenness is rather minute. Therefore, it is omitted in the first FIG. Next, a dopant is provided and a method of utilizing thermal diffusion is at 099139446. Form No. A0101 Page 3 of 22 0992068733-0 201222851 The first surface S1 forms an emitter layer I! (Mitterlayer) composed of an N+ type semiconductor And a pn junction is formed between the P-type semiconductor substrate 1A and the emitter layer 11. At this time, a Phosphorous silicate glass (PSG) is also formed on the emitter layer 11, as shown in the first panel B. Thereafter, the surface of the phosphorous glass layer 12 is removed by etching as shown in the first panel C. [0004] [0005] Next, as shown in FIG. D, a first anti-reflection film 13 made of a nitrogen-niobium compound (SiNx) is formed on the emitter layer 12 by means of deposition. -reflection coating, ARC) to reduce the reflectivity of the light and protect the emitter layer u. Thereafter, as shown in the first image E, doping is performed on the second surface S2 with boron tribromide (BBr) as a diffusion source to form a back surface field (BSF), and A second anti-reflection film 15 composed of a nitrogen ruthenium compound is deposited, and then the aluminum conductive material is printed on the second surface by using a screen printing technique, and the silver conductive material is printed in the same manner. On the first surface 81. Finally, a Firing step is performed to cause the first surface S1 to produce the first electrode 16, and the second surface S2 to produce the second electrode 17, thereby completing the fabrication of the solar cell. However, in the manufacturing process of the conventional double-sided solar cell, the emitter layer u composed of an N + -type semiconductor is formed on the first surface 31 by providing a dopant and utilizing thermal diffusion, and a pn junction is formed. Adjusting the emitter concentration to heavy doping in this process can reduce the contact resistance of the battery but increase the surface recombination rate and adjust the emitter concentration to lightly doping to reduce the surface recombination rate, but it will improve the battery. Connected to 099139446 Form No. A0101 Page 4 / Total 22 Page 0992068733-0 201222851 The electric steepness, therefore, the adjustment of the concentration of the emitter layer can not make the surface recombination and the improvement of the contact resistance of the battery can be the best of both worlds, in addition to the second two S 2 is to form the back surface electric field layer by diffusion method. Therefore, the above-mentioned t kinds are used, because the process heat budget of the thermal diffusion process is too large and the parameter control is not easy, the process precision is reduced, and a lot of materials are added along with the Time costs. [0006] Furthermore, the conventional technique of printing a conductive material on the entire surface of the second surface S2 when printing a conductive material on the second surface S2 by using a screen printing technique may cause a surface recombination rate due to the characteristics of the metal. High and make the bow bowing 'cause the process instability, the photoelectric conversion efficiency of the double-sided solar cell is poor' affects the quality of the process [0007] [Summary of the invention] ❹ Method of electric shock conversion disadvantages The main purpose of the case In order to provide a double-sided solar cell manufacturing process, in the manufacturing process of the conventional double-sided solar cell, the photoelectric conversion rate of the solar cell is affected by the high rate of re-bonding with the surface P, and the process is complicated to cause time and materials. Cost increase, etc. [0008] Another object of the present invention is to provide a double-sided solar cell system, method A, using a thermal oxide layer as a protective layer and a barrier in the diffusion process to form a selective emitter, and using a back surface local contact The passivation effect of the structure with the back surface oxide layer replaces the surface of the back surface, and the electric field layer is called The low surface recombination rate enhances the photo-electric conversion efficiency of double-sided solar cells, as well as simplifying process steps and reducing time and material costs. 099139446 Form No. A0101 Page 5 of 22 0992068733-0 201222851 [0009] In order to achieve the above object, one of the broader aspects of the present invention provides a method for manufacturing a double-sided solar cell, comprising at least the steps of: (a) providing a semiconductor substrate; (b) simultaneously forming a first thermal oxide layer on the first surface of the semiconductor substrate and forming a second thermal oxide layer on the second surface of the semiconductor substrate; (c) forming a second anti-reflective film on the second thermal oxide layer (d) removing a portion of the first thermal oxide layer and masking the at least a portion of the semiconductor substrate with the first thermal oxide layer, and having a blend of concentrated and lightly different regions in a single diffusion process step The impurity concentration forms a selective emitter, wherein a pn junction is formed between the semiconductor substrate and the emitter; (e) forming a first anti-reflection film on the first surface; (f) forming at least one second electrode on the second surface; And (g) forming at least one first electrode on the first surface. [0010] In order to achieve the above object, another broad aspect of the present invention provides a method for manufacturing a double-sided solar cell, comprising at least the steps of: (a) providing a semiconductor substrate; (b) forming a first thermal oxide layer on the semiconductor a first surface of the substrate and a second thermal oxide layer formed on the second surface of the semiconductor substrate; (c) forming a second anti-reflective film on the second thermal oxide layer; (d) forming a selective shot in at least a portion of the semiconductor substrate a pole, wherein a pn junction is formed between the semiconductor substrate and the emitter; (e) forming a first anti-reflection film on the first surface; (f) forming a partial region of the at least one second electrode on the second surface; and (g) Forming at least one first electrode on the first surface. [Embodiment] Some exemplary embodiments embodying the features and advantages of the present invention will be described in detail in the following description. It should be understood that the present invention can be variously changed in various aspects without departing from the scope of the present invention, and the description and illustration thereof are used as an explanation in essence, and are not intended to limit the form of 099139446. No. A0101 Page 6 of 22 0992068733-0 201222851 [0012]
DD
[0013] Ο [0014] 請參閱第二圖A-J，其係為本案較佳實施例之雙面太 陽能電池之製造流程結構示意圖。如第二圖A所示，首先 ，提供半導體基板20，並將半導體基板20的第一表面S1 以及第二表面S2形成凹凸的紋理，以降低光線的反射率 ，其中由於凹凸紋理相當細微，因此在第二圖A中省略標 示。於一些實施例中，半導體基板20可為但不限於P型矽 基板，且於半導體基板20之第一表面S1與第二表面S2形 成凹凸紋理的方式可採用但不限於濕蝕刻或反應性離子 蝕刻等方式。 接著，如第二圖B所示，同時於半導體基板20之第一 表面S1(或稱前表面）形成第一熱氧化層21以及第二表面 S2(或稱背表面）形成第二熱氧化層22，其中，形成第一 熱氧化層21以及第二熱氧化層22之方法係以爐管製程方 法實現，且爐管製程方法可為但不限於氣相沉積法 (Vapor Deposition)、化學氣相沉積法（Chemical Vapor Deposition，CVD)或電.聚輔助化學氣相沉積法 (Plasma-Enhanced Chemical Vapor Deposition, PECVD) 〇 於一些實施例中，第一熱氧化層21以及第二熱氧化 層21可由例如二氧化矽所構成，且第一熱氧化層21可作 為遮罩以及擴散時之屏障，而使本案之選擇性射極之製 程可以實現，第二熱氧化層22則可作為第二表面S2之保 護層，但不以此為限，藉由第一熱氧化層21以及第二熱 氧化層22可同時作為保護層以及擴散屏障之特性，可減 099139446 表單編號A0101 第7頁/共22頁 0992068733-0 201222851 少傳統製程中’需要額外形成保護層或額外形成擴散屏 障之步驟，因而減少物料與時間成本，且可有效提昇雙 面太陽能電池之光、電品質與光電轉換效率。 [0015] [0016] [0017] 隨後，如第二圖C所示，於半導體基板20之第二表面 S2之第二熱氧化層22上形成第二抗反射膜24，其中第二 抗反射膜2 4較佳係利用電漿輔助化學氣相沉積法沉積一 氮矽化合物層所實現，但不以此為限。第二抗反射膜24 係具有可降低光線的反射率並具有高通透性等優點，可 使氫由第二抗反射膜24内大量穿透至半導體基板20内部 ’以進行氫鈍化過程，進而提昇太陽能電池之效能。於 一些實施例中，第二抗反射膜24可由氮化矽、二氧化矽 、二氧化鈦、氧化鋅、氧化錫、二氧化鎂等材質構成， 且不以此為限。 其次，如第二圖D所示，移除部份之第一熱氧化層21 ，並暴露出部份之半導體基板2p，以彫成複數個開口 21a 。於此實施例中，移除部份之(第一熱氧化層21的方法可 採用但不限於蝕刻方式或雷射加熱方式。 接著，再如第二圖E所示，利用第一熱氧化層21作為 遮罩以及擴散之屏障，以提供摻雜劑以及利用例如熱擴 散的方式，於半導體基板20之開口區域21a形成重摻雜區 域25a，在第一表面S1上有熱氧化層的區域上，因熱氧化 層的作用而形成輕摻雜區域25b，亦即形成選擇性射極25 ’例如但不限於N型之射極。換言之，可在一次擴散的 製程步驟中使其同時有濃 '淡不同區域的捧雜j農度形成 出選擇性射極25。其中，熱擴散之擴散源可為三氣氧碟 099139446 表單編號A0101 第8頁/共22頁 0992068733-0 201222851 (POC13)，且在半導體基板20與射極25之間形成ρη接面 ，此時，在第一熱氧化層21以及射極25上亦會形成碟石夕 玻璃層26。其後，如第二圖F所示，再利用蝕刻的方式將 磷矽玻璃層26移除，於一些實施例中，於移除磷矽玻璃 層26時，亦可同時移除至少部份之第一熱氧化層21，但 不以此為限。於另一些實施例中，係以單面蝕刻（Si ng^ e side etch)之方式移除磷矽玻璃層26與至少部份之第__ 熱氧化層21 ’但不以此為限’且單面蝕刻可為但不限於 Ο [0018] 化學蝕刻（Chemical etch)或是乾蝕刻（Dry etch)。 ❹ [0019] 之後，如第二圓G所示，於半導體基板20之第一表面 S1上形成第一抗反射膜23 ’其申第一抗.反射膜23較佳係 以電漿輔助化學氣相沉積法沉積一層由氮矽化合物所實 現。第一抗反射膜23可以降低光線的反射率並保護射極 25，在製程中氫可以在半導體基板2〇表面以及穿透至半 導體基板20内部，以進行氫鈍化過程，進而提昇太陽能 電池之效能。於一些實施例中，第一抗反射膜23可由氮 化石夕 '二氧化梦、二氧化鈦、氧化鋅、氧化錫、二氧化 鎂等材質構成，且不以此為限。 然後，如第二圖Η所示，移除部份之第二抗反射膜24 以及部份之第二熱氧化層22，並暴露出部份之半導體基 板20 ’以形成複數個開口 22a。於此實施例中，移除部份 之第二抗反射膜24以及部份之第二熱氧化層22的方法可 採用但不限於姓刻方式或雷射加熱方式。 接著，則如第二圖I所示’於第二表面s2進行金屬鍍 膜（Metallization)過程，其中，金屬鍵膜過程係可 099139446 表單編號A0101 第9頁/共22頁 0992068733-0 [0020] 201222851 採用網版印刷技術或是電鍛（Plating)技術將弟二導電 材料2 8 a，例如銘、銀，但不以此為限，形成於第二表面 S2之部分區域上。於本實施例中，第二導電材料28a係以 鋁為較佳，當以網版印刷技術將鋁導電材料形成於第二 表面S2之部分區域後，則可進行燒結步驟，用以於第二 表面S2之開口 22a處，形成第二電極28並且在燒結的過程 中鋁可藉此摻雜至半導體基板20内。 [0021] [0022] [0023] 最後，如第二圖J所示，於第一表面S1上進行金屬鍍 膜過程，且於此實施例中，係使用網版印刷技術將第一 導電材料2 7 a，例如鋁、銀，但不以此為限，形成於第一 表面S1之部分區域上，接著進行燒結步驟，使第一表面 S1上之第一導電材料27a形成第一電極27，其中第一電極 27穿過第一抗反射膜23並延伸連接至射極25，藉此以完 成雙面太陽能電池之製造。 於另一些實施例中，前述之第一導電材料27a以及第 二導電材料28a亦可藉由一共燒結步驟形成第一電極27與 第二電極28。 綜上所述，本案之雙面太陽能電池之製造方法，藉 由熱氧化層之特性以作為前表面之遮罩與擴散屏障以及 背表面之保護層，藉此可實現以單一擴散步驟形成選擇 性射極，可確實簡化製程步驟，同時減少時間以及物料 成本。此外，利用具有選擇性射極的雙面太陽能電池可 解決習用技術所面臨之接觸電阻以及表面再結合速率較 高的問題，且較高摻雜濃度的區域可以提供較佳的歐姆 接觸（ohmic contact)以及較輕摻雜濃度的區域可以提 099139446 表單編號A0101 第10頁/共22頁 0992068733-0 201222851 供較長的載子生存期（carrier life time)。此外，本 案之製程方法係使用背表面局部接觸結構配合表面氧化 層鈍化效果取代背面整面的表面電場層，可達到降低表 面再結合速率以及提升雙面太陽能電池之光電轉換效率 之功效。 [0024] 縱使本發明已由上述之實施例詳細敘述而可由熟悉 本技藝之人士任施匠思而為諸般修飾，然皆不脫如附申 請專利範圍所欲保護者。 〇 【圖式簡單說明】 [0025] 第一圖A-E係為習用雙面單晶或多晶矽之太陽能電池製造 流程結構示意圖。 [0026] 第二圖A-J係為本案較佳實施例之雙面太陽能電池之製造 流程結構不意圖。 【主要元件符號說明】 [0027] 半導體基板： 10 ' 20 [0028] 射極層：11 [0029] 磷矽玻璃層： 12、26 [0030] 第一抗反射膜 ：13 ' 23 [0031] 背表面電場層 ：14 [0032] 第二抗反射膜 :15 、 24 [0033] 第一電極：16 '27 [0034] 第二電極：17 '28 表單編號A0101 099139446 第11頁/共22頁 0992068733-0 201222851 [0035] 第一熱氧化層：21 [0036] 第二熱氧化層：22 [0037] 開口 ： 21 a、2 2 a [0038] 射極：25 [0039] 重摻雜區域：25a [0040] 輕摻雜區域：2 5 b [0041] 第一導電材料：27a [0042] 第二導電材料：28a [0043] S1 :第一表面 [0044] S2 :第二表面 099139446 表單編號A0101 第12頁/共22頁 0992068733-0[0013] Please refer to FIG. 2A-J, which is a schematic structural diagram of a manufacturing process of a double-sided solar cell according to a preferred embodiment of the present invention. As shown in FIG. A, first, the semiconductor substrate 20 is provided, and the first surface S1 and the second surface S2 of the semiconductor substrate 20 are formed into a textured texture to reduce the reflectance of light, wherein the uneven texture is rather fine. The indication is omitted in the second diagram A. In some embodiments, the semiconductor substrate 20 can be, but not limited to, a P-type germanium substrate, and the concave and white texture can be formed on the first surface S1 and the second surface S2 of the semiconductor substrate 20, but is not limited to wet etching or reactive ions. Etching and other methods. Next, as shown in FIG. 24B, the first thermal oxide layer 21 and the second surface S2 (or the back surface) are simultaneously formed on the first surface S1 (or the front surface) of the semiconductor substrate 20 to form a second thermal oxide layer. 22, wherein the method of forming the first thermal oxide layer 21 and the second thermal oxide layer 22 is implemented by a furnace control method, and the furnace control method may be, but not limited to, Vapor Deposition, chemical vapor phase Chemical Vapor Deposition (CVD) or Plasma-Enhanced Chemical Vapor Deposition (PECVD). In some embodiments, the first thermal oxide layer 21 and the second thermal oxide layer 21 may be For example, the ruthenium dioxide is formed, and the first thermal oxide layer 21 can serve as a mask and a barrier for diffusion, so that the selective emitter process of the present invention can be realized, and the second thermal oxide layer 22 can be used as the second surface S2. The protective layer, but not limited thereto, can be reduced as a protective layer and a diffusion barrier by the first thermal oxide layer 21 and the second thermal oxide layer 22, and can be reduced by 099139446. Form No. A0101 Page 7 of 22 0992068733- 0 201222851 In the less traditional process, the need to additionally form a protective layer or additionally form a diffusion barrier, thereby reducing material and time costs, and effectively improving the light, electrical quality and photoelectric conversion efficiency of the double-sided solar cell. [0017] Subsequently, as shown in FIG. 2C, a second anti-reflection film 24 is formed on the second thermal oxide layer 22 of the second surface S2 of the semiconductor substrate 20, wherein the second anti-reflection film 2 4 is preferably realized by plasma-assisted chemical vapor deposition of a layer of a ruthenium nitride compound, but is not limited thereto. The second anti-reflection film 24 has the advantages of reducing the reflectance of light and having high permeability, and allowing hydrogen to penetrate into the inside of the semiconductor substrate 20 in a large amount in the second anti-reflection film 24 to perform a hydrogen passivation process. Improve the performance of solar cells. In some embodiments, the second anti-reflection film 24 may be made of a material such as tantalum nitride, hafnium oxide, titanium dioxide, zinc oxide, tin oxide, magnesium dioxide, or the like, and is not limited thereto. Next, as shown in Fig. D, a portion of the first thermal oxide layer 21 is removed, and a portion of the semiconductor substrate 2p is exposed to engrave a plurality of openings 21a. In this embodiment, the portion of the first thermal oxide layer 21 may be removed, but is not limited to an etching method or a laser heating method. Next, as shown in FIG. 21 as a mask and a diffusion barrier to provide a dopant and to form a heavily doped region 25a in the open region 21a of the semiconductor substrate 20 by means of, for example, thermal diffusion, on the region of the first surface S1 having a thermal oxide layer The lightly doped region 25b is formed by the action of the thermal oxide layer, that is, the selective emitter 25' is formed, for example, but not limited to, the N-type emitter. In other words, it can be simultaneously concentrated in the process step of one diffusion. The selective ejector 25 is formed in a different area, wherein the diffusion source of the thermal diffusion may be a three-gas oxygen dish 099139446 Form No. A0101 Page 8 of 22 0992068733-0 201222851 (POC13), and A pn junction is formed between the semiconductor substrate 20 and the emitter 25. At this time, the Sauvignon glass layer 26 is also formed on the first thermal oxide layer 21 and the emitter 25. Thereafter, as shown in FIG. And then etching the phosphorous glass layer 26 by etching In some embodiments, at least a portion of the first thermal oxide layer 21 may be removed simultaneously, but not limited thereto, in the removal of the phosphorous-glass layer 26. In other embodiments, Surface etching (Si ng ^ e side etch) removes the phosphorous-glass layer 26 and at least a portion of the __ thermal oxide layer 21 'but not limited thereto' and the single-sided etching may be but not limited to Ο [ 0018] Chemical etch or Dry etch. [0019] Thereafter, as shown by the second circle G, a first anti-reflection film 23' is formed on the first surface S1 of the semiconductor substrate 20. The first anti-reflection film 23 is preferably deposited by a plasma-assisted chemical vapor deposition method with a nitrogen ruthenium compound. The first anti-reflection film 23 can reduce the reflectance of the light and protect the emitter 25 in the process. Hydrogen can pass through the surface of the semiconductor substrate 2 and penetrate into the interior of the semiconductor substrate 20 to perform a hydrogen passivation process, thereby improving the performance of the solar cell. In some embodiments, the first anti-reflective film 23 can be nitrided by the dialysis. , titanium dioxide, zinc oxide, tin oxide, magnesium dioxide, etc. The composition is not limited thereto. Then, as shown in FIG. 2, a part of the second anti-reflection film 24 and a part of the second thermal oxide layer 22 are removed, and a part of the semiconductor substrate is exposed. 20' to form a plurality of openings 22a. In this embodiment, the method of removing a portion of the second anti-reflective film 24 and a portion of the second thermal oxide layer 22 may be performed by, but not limited to, surname or laser heating. Then, as shown in FIG. 1A, a metallization process is performed on the second surface s2, wherein the metal bond film process can be 099139446. Form No. A0101 Page 9 / Total 22 Page 0992068733-0 [0020 201222851 The screen printing technology or the electric forging (Plating) technology is used to form the second conductive material 28 8 a, for example, inscription, silver, but not limited thereto, formed on a part of the second surface S2. In this embodiment, the second conductive material 28a is preferably aluminum. When the aluminum conductive material is formed on a portion of the second surface S2 by screen printing technology, a sintering step may be performed for the second At the opening 22a of the surface S2, the second electrode 28 is formed and aluminum can be doped into the semiconductor substrate 20 during the sintering process. [0022] Finally, as shown in the second figure J, the metal plating process is performed on the first surface S1, and in this embodiment, the first conductive material is used by using the screen printing technology. a, for example, aluminum, silver, but not limited thereto, formed on a partial region of the first surface S1, followed by a sintering step, so that the first conductive material 27a on the first surface S1 forms the first electrode 27, wherein An electrode 27 passes through the first anti-reflection film 23 and extends to the emitter 25, thereby completing the manufacture of the double-sided solar cell. In other embodiments, the first conductive material 27a and the second conductive material 28a may also form the first electrode 27 and the second electrode 28 by a co-sintering step. In summary, the method for manufacturing a double-sided solar cell of the present invention is characterized in that the thermal oxide layer serves as a mask for the front surface and a diffusion barrier and a protective layer for the back surface, thereby forming a selective diffusion step. The emitters simplify the process steps while reducing time and material costs. In addition, the use of a double-sided solar cell with a selective emitter can solve the problem of high contact resistance and high surface recombination rate faced by conventional techniques, and a region with a higher doping concentration can provide a better ohmic contact. ) and areas with lighter doping concentrations can be raised in 099139446 Form No. A0101 Page 10 of 22 0992068733-0 201222851 For longer carrier life time. In addition, the process method of the present invention uses the back surface local contact structure and the surface oxide passivation effect to replace the surface electric field layer on the entire back surface, thereby achieving the effect of reducing the surface recombination rate and improving the photoelectric conversion efficiency of the double-sided solar cell. [0024] The present invention has been described in detail by the above-described embodiments, and may be modified by those skilled in the art, without departing from the scope of the appended claims. 〇 [Simple description of the drawing] [0025] The first figure A-E is a schematic structural diagram of a solar cell manufacturing process of a conventional double-sided single crystal or polycrystalline silicon. The second drawing A-J is not intended to be a manufacturing process structure of the double-sided solar cell of the preferred embodiment of the present invention. [Major component symbol description] [0027] Semiconductor substrate: 10' 20 [0028] Emitter layer: 11 [0029] Phosphorus glass layer: 12, 26 [0030] First anti-reflection film: 13' 23 [0031] Back Surface electric field layer: 14 [0032] Second anti-reflection film: 15, 24 [0033] First electrode: 16 '27 [0034] Second electrode: 17 '28 Form No. A0101 099139446 Page 11 of 22 0992068733- 0 201222851 [0035] First thermal oxide layer: 21 [0036] Second thermal oxide layer: 22 [0037] Opening: 21 a, 2 2 a [0038] Emitter: 25 [0039] heavily doped region: 25a [ 0040] Lightly doped region: 2 5 b [0041] First conductive material: 27a [0042] Second conductive material: 28a [1404] S1: first surface [0044] S2: second surface 099139446 Form No. A0101 No. 12 Page / Total 22 pages 0992068733-0