201248874 六、發明說明： 【發明所屬之技術領域】 本發明是有關於一種太陽能電池及其製造方法，特別 是指一種具有背電場結構的太陽能電池及其製造方法。 【先前技術】 參閱圖1，為一種已知太陽能電池i的製造流程示意圖 ，在此先說明該太陽能電池1的結構（請參考圖丨的最後一 圖）’主要包含：一晶片11、一介電層12、數個形成於該晶 片11的局部部位的背電場結構13(1〇cal back surface fieid， 簡稱LBSF) ’以及一金屬膠層14。 亚巴枯p型 战日日月11用於將光能轉換成電能 _____^ 石夕基板、形成於該基板上的η型射極層，以及抗反射膜等 膜層該；I電層12形成於該晶片u的—背面⑴，用於降 低載子在該晶# U表面複合（re_binati〇n)的速率，提升 太陽能電池i的效率。所述介電層12具有數個貫穿的穿槽 12^所述背電場結構13對應所述穿槽i2i而形成於晶片 11月面111處’其為載子濃度大於該p型⑦基板的載子濃 度的P型半導體層’利用其電場作用阻止電子朝該晶片U 的背面111方向移動，使電子被收集於該晶片η的η型射 極層’以提升轉換效率。而該金屬膠層14是由銘膠乾燥形 成，位於該介電層12的表面Μ部伸人介電層12的穿槽 201248874 111形成-層完整的介電層12，並將該介電層12的局部钮 刻移除而形成㈣121’再利用網印方式將轉塗布在該介 電層12表面以形成該金屬膠層14。接著燒結該晶片n，紹 會擴散進入該晶片11中，使該晶片11的局部形成由鋁矽 混合材料形成的背電場結構13。 然而，由於鋁膠直接塗布在該介電層12表面，在高溫 燒結過程中，鋁膠材料也會擴散、侵蝕該介電層12，導致 介電層12的結構被破壞，而且鋁膠除了以鋁為主要成分外 ，還包含許多不同成分，例如其中的玻璃材質也容易與該 介電層12產生反應，因而影響該介電| 12的品質及功能 ，使轉換效率下降。 【發明内容】 因此，本發明之目的，即在提供一種介電層品質良好 ，能提升轉換效率的具有背電場結構的太陽能電池及其製 造方法。 於疋’本發明具有背電場結構的太陽能電池，包含： 一晶片、一介電層、數個背電場結構、一金屬阻障層以 及一導電膠層。 該晶片用於將光能轉換成電能，並包括一入光面以 及一相反於該入光面的背面。該介電層包括一朝向該晶片 的背面的第一面、一相反於該第一面的第二面，以及數個 貫穿該第一面及第二面的穿槽。所述背電場結構各別對應 所述穿槽而位於該晶片的背面處。 該金屬阻障層彼覆在該介電層的第二面，並具有數個 4 201248874 各別對應且遠iS # ^ β & μ 硬通該介電層的穿槽的穿孔，該金屬阻障層的 材料為銀、翻、^ ··、欽鶴合金、鶴、鈦、鉻、翻鶴合金、翻、 金、錦，每卜, ^工述的任一組合之合金。該導電膠層包括一個 ;該金屬阻障層的表面的表層部，以及數個彼此間隔並 自β表層#朝所述穿孔及穿槽突伸且接觸背電場結構的導 電接觸部。 本發明具有背電場結構的太陽能電池的製造方法，包 含： (Α)準備該用於將光能轉換成電能的晶片，在該晶片的 背面形成該介電層； (Β)在該介電層的表面形成該金屬阻障層，所述金屬阻 障層的材料為銀ϋ鶴合金、鶴、钦、絡、翻鶴合金 、鉑、金、鎳，或上述的任一組合之合金； (C) 在該金屬阻障層的表面披覆一層導電膠，並使該導 電膠的部分材料進入該金屬阻障層及該介電層；及 (D) 對該晶片施以熱處理，使該導電膠固化成為該導電 膠層，而且在熱處理過程中，該導電膠位於該介電層中的 材料經由該晶片的背面擴散進入該晶片，使該晶片形成數 個位於該背面處的背電場結構。 本發明之功效：藉由在製作該導電膠層之前，先形成 該金屬阻障層作為介電層表面的屏障，可以防止燒結過程 該導電膠材料擴散進入該介電層，進而避免導電膠對該介 電層造成損害，使介電層具有良好品質及良好的降低載子 複合速率的功效，能提升電池轉換效率。 5 201248874 【實施方式】 有關本發明之前述及其他技術内容、特點與功效，在 以下配合參考圖式之二個較佳實施例的詳細說明中，將可 清楚的呈現。在本發明被詳細描述前，要注意的是，在以 下的說明内容中’類似的元件是以相同的編號來表示。 參閱圖2’本發明具有背電場結構的太陽能電池的第一 較佳實施例包含：一晶片2、一介電層3、數個背電場結構 4、一金屬阻障層5，以及一導電膠層6。 該晶片2用於將光能轉換成電能，並包括一入光面21 ，以及一相反於該入光面21的背面22。該晶片2實際上包 括一個具有該背面22的基板23、形成於該基板23上的射 極層，以及抗反射膜等膜層，本實施例的基板23為p型矽 基板23，該射極層為n型射極層，由於該晶片2非本發明 的改良重點，在此不詳細說明，而且本發明實施時不須限 制該晶片2的具體結構及層體數量，因為可以視太陽能電 池的需求而增添不同功能的膜層，圖2只以—層膜層示竟 基板23上的所有膜層。 〜201248874 VI. Description of the Invention: [Technical Field] The present invention relates to a solar cell and a method of manufacturing the same, and more particularly to a solar cell having a back electric field structure and a method of fabricating the same. [Prior Art] Referring to Fig. 1, a schematic diagram of a manufacturing process of a known solar cell i, the structure of the solar cell 1 (refer to the last figure of Fig. ') will be described first, which mainly includes: a wafer 11, a medium The electric layer 12, a plurality of back electric field structures 13 (LBSF) formed on a part of the wafer 11, and a metal glue layer 14. The Abbath p-type war day and day is used to convert light energy into electrical energy _____^ Shixi substrate, n-type emitter layer formed on the substrate, and anti-reflection film and the like; I electrical layer 12 The back surface (1) formed on the wafer u is used to reduce the rate at which the carrier recombines on the surface of the crystal, and to improve the efficiency of the solar cell i. The dielectric layer 12 has a plurality of through-holes 12. The back-field structure 13 is formed on the wafer 11-side 111 corresponding to the through-hole i2i. The carrier concentration is greater than the load of the p-type 7 substrate. The sub-concentration P-type semiconductor layer 'is prevented from moving toward the back surface 111 of the wafer U by its electric field action, so that electrons are collected in the n-type emitter layer ' of the wafer n to improve conversion efficiency. The metallization layer 14 is formed by drying the gelatin. The surface of the dielectric layer 12 is formed on the surface of the dielectric layer 12 and extends through the trenches 201248874 111 to form a complete dielectric layer 12, and the dielectric layer is formed. The partial button of 12 is removed to form (four) 121' and then transferred to the surface of the dielectric layer 12 by screen printing to form the metal glue layer 14. The wafer n is then sintered and diffused into the wafer 11 such that a portion of the wafer 11 forms a back electric field structure 13 formed of an aluminum-niobium mixed material. However, since the aluminum paste is directly coated on the surface of the dielectric layer 12, during the high-temperature sintering process, the aluminum paste material also diffuses and erodes the dielectric layer 12, causing the structure of the dielectric layer 12 to be destroyed, and the aluminum paste is removed. Aluminum is a main component, and also contains many different components. For example, the glass material therein is also likely to react with the dielectric layer 12, thereby affecting the quality and function of the dielectric|12, and reducing the conversion efficiency. SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a solar cell having a back electric field structure which is excellent in dielectric layer quality and capable of improving conversion efficiency, and a method of fabricating the same. The solar cell having the back electric field structure of the present invention comprises: a wafer, a dielectric layer, a plurality of back electric field structures, a metal barrier layer, and a conductive adhesive layer. The wafer is used to convert light energy into electrical energy and includes a light incident surface and a back surface opposite the light incident surface. The dielectric layer includes a first side facing the back side of the wafer, a second side opposite the first side, and a plurality of through slots extending through the first side and the second side. The back electric field structures are each located at the back of the wafer corresponding to the through slots. The metal barrier layer covers the second side of the dielectric layer, and has a plurality of 4 201248874 corresponding and far iS # ^ β & μ hard through the through hole of the dielectric layer, the metal resistance The material of the barrier layer is an alloy of any combination of silver, turn, ^ ··, jinhe alloy, crane, titanium, chrome, shovel alloy, turn, gold, brocade, and each. The conductive adhesive layer includes a surface portion of the surface of the metal barrier layer, and a plurality of conductive contacts spaced apart from each other and extending from the β surface layer toward the through hole and the through hole and contacting the back electric field structure. A method of fabricating a solar cell having a back electric field structure, comprising: preparing a wafer for converting light energy into electrical energy, forming the dielectric layer on a back surface of the wafer; (Β) in the dielectric layer Forming the metal barrier layer, the material of the metal barrier layer being a silver samarium alloy, a crane, a chrysanthemum, a sling, an alloy, a platinum, a gold, a nickel, or an alloy of any combination thereof; a surface of the metal barrier layer is coated with a conductive paste, and a portion of the conductive paste is introduced into the metal barrier layer and the dielectric layer; and (D) the wafer is heat treated to make the conductive paste The conductive adhesive layer is cured, and during the heat treatment, the material of the conductive paste in the dielectric layer diffuses into the wafer through the back surface of the wafer, so that the wafer forms a plurality of back electric field structures at the back surface. The effect of the invention: by forming the metal barrier layer as a barrier of the surface of the dielectric layer before the conductive adhesive layer is formed, the conductive adhesive material can be prevented from diffusing into the dielectric layer during the sintering process, thereby avoiding the conductive adhesive pair The dielectric layer causes damage, and the dielectric layer has good quality and good effect of reducing the recombination rate of the carrier, and can improve the conversion efficiency of the battery. The above and other technical contents, features and effects of the present invention will be apparent from the following detailed description of the preferred embodiments of the invention. Before the present invention is described in detail, it is to be noted that in the following description, similar elements are denoted by the same reference numerals. Referring to FIG. 2, a first preferred embodiment of a solar cell having a back electric field structure of the present invention comprises: a wafer 2, a dielectric layer 3, a plurality of back electric field structures 4, a metal barrier layer 5, and a conductive paste. Layer 6. The wafer 2 is used to convert light energy into electrical energy and includes a light incident surface 21 and a back surface 22 opposite to the light incident surface 21. The wafer 2 actually includes a substrate 23 having the back surface 22, an emitter layer formed on the substrate 23, and a film layer such as an anti-reflection film. The substrate 23 of the present embodiment is a p-type germanium substrate 23, and the emitter The layer is an n-type emitter layer. Since the wafer 2 is not a modification of the present invention, it will not be described in detail herein, and the specific structure and the number of layers of the wafer 2 need not be limited in the implementation of the present invention, because the solar cell can be regarded as The film layers with different functions are added as required. In Fig. 2, only all the film layers on the substrate 23 are shown in a layer. ~
該介電層3位於該晶片2的背面22，並包括一朝向 晶片2的背面22的第一面31、一相反於該第一面μ。的 二面32’以及數個貫穿該第一面31及第二面32的穿槽 ’該介電層3的材料為氧化物、氮化物等介電材料 化物與氮化物的複合材料，例如：抓、叫、Α! 〇 SThe dielectric layer 3 is located on the back side 22 of the wafer 2 and includes a first side 31 facing the back side 22 of the wafer 2, opposite to the first side μ. The two sides 32' and the plurality of through grooves of the first surface 31 and the second surface 32. The material of the dielectric layer 3 is a composite material of a dielectric material such as an oxide or a nitride and a nitride, for example: Grab, call, oh! 〇 S
Si〇2/SiNX，Al2〇3/SlN-^^3；^ 降低表面缺陷’進而降低載子在該晶片2的背面 6 201248874 (recombination)的速率，提升電池的轉換效率。 所述背電場結構4對應所述穿槽33而形成於晶片2的 背面22處’本實施例的背電場結構4為銘石夕（A1_Si)混合材 料，其為載子it度大於p _基板23的載子濃度的p型半 導體層（-般又稱為p+層），利用其電場作用阻擋電子朝該晶 片2的背面22方向移動，使電子被收集於該晶片2的n型 射極層，因此藉由㈣場結# 4能提升載子收集效率及轉 換效率。 需要說明的是，當晶片2的基板23為η型基板時，該 背電場結構4就必需為載子濃度大於該基板23的載子濃度 的η型半導體層（η+層）。 又 該金屬阻障層5披覆在該介電層3的第二面32，而且 具有數個各別對應且連通該介電層3的穿槽幻的穿孔Η， 該金屬阻障層5的厚度約為1G奈米（nm)~1()微米（㈣，可 提供良好的保護介電層3的效果，以及良好的導電性及光 反射作用。該金屬阻障層5的材料為銀（Ag)、叫M〇)、鈦鎢 合金(Tiw)、鎢(w)、鈦㈤、鉻(Cr)、鉬鶴合金(M〇w)、鉑 (Pt)、金（Au)、鎳（Ni)，或上述的任一組合，此等材質的選 用，主要在於使該金屬阻障層5形成可導電的緻密薄膜。 本實施例的導電膠層6的材質為鋁或鋁合金，所述鋁 合金例如銀鋁合金、鋁矽合金但不限於此，並包括一個位 於該金屬阻障層5的表面且厚度約為1〇#m〜5〇//m的表層 部61,以及數個彼此間隔並自該表層部61朝所述穿孔si 及穿槽33突伸的導電接觸部62 ,所述導電接觸部62接觸 201248874 背電場結構4而形成電連接。 參閱圖2、3、4,本發明具有背電場結構的太陽能電池 的製造方法之第一較佳實施例，包含： ⑴進仃步驟71 :利用例如諸錢料真线膜方式 ，在該晶片2的背面22鍍上一層連續完整的介電層3,其 材質如前述，為氧化物薄膜、氮化物薄膜或氧化物與氮化 物的複合材料。當然，該晶片2也可以事先製作有所需要 的層體’例如必需利用擴散製程在該p型㈣基板23上形 成η型射極層’以及利用真空鑛膜方式形成抗反射膜等步 驟’但由於晶片2本身的製程非本發明的改良重點，所以 不再說明。 (2) 進行步驟72:利用例如蒸鍍或濺鍍等真空鍍膜方式 在》玄"電層3的第二面32披覆該金屬阻障層5，其材料 如前述為金屬材質，在此不再說明。 (3) 進打步驟73:在該介電層3上形成所述穿槽33及 該金屬阻障層5上形成所述穿孔51，此步驟可以利用雷射 剝除（laser ablation)方式，對該金屬阻障層5之局部部位照 射雷射光’接著使該金屬阻障層5的照光部位及該介電層3 的對應部位被蝕刻移除而形成所述穿孔51及穿槽％。或者 可以利用網印機將具有钱刻㊣力的钱刻膠（etching paste)塗 布在δ亥金屬阻障層5的局部表面上，再利用水洗方式或相 對應的㈣液將㈣膠清洗移除後，即可使該金屬阻障層5 的局部部位及該介電層3的對應部位—併㈣移除而形成 所述穿孔51及穿槽33。 8 201248874 (4)進行步驟74 :在該金屬阻障層5的表面披覆一層導 電膠6’ ’本實施例的導電膠6’為膏液狀的鋁膠可以利用 網印（screen priming)或喷印（ink jet pdnting)方式塗布形成 ，而且導電膠6’的部分材料也會流動填充於所述穿孔51及 穿槽33而成為該導電膠層6的導電接觸部62。 (5)進行步驟75 :對該晶片2施以熱處理化如 treatment)，使該導電膠6,乾燥固化成為該導電膠層6。本 實細例所述熱處理，其具體方式為高溫燒結⑴以叩），而且 在熱處理過程中，位於穿槽33中的導電膠6，内的㈣由該 曰日片2的背面22擴散進入晶片2内部，鋁摻雜於該晶片2 的基板23中而與基板23的矽化合，使該晶片2在該背面 22處且對應於穿槽33的位置形成所述背電場結構*。 所述導電膠層6的導電接觸部62可以為長條狀、點狀 或其它形狀H形成前述穿槽33及穿孔51時必需製 作出預定的形狀，使導電接觸部62也具有預定形狀。 立本發明藉由在製作該導電膠層6之前，先形成該金屬 阻P早層^作為介電& 3表面的屏障，透過該金屬阻障層$ 特定材f使其形成緻密薄膜，可以防止燒結過程中 =導電膠6’的材料擴散進人該介電層3,避免導電膠6,對該 ::層3造成損害，使介…具有良好品質及良好的降 :載子複合速率的功效，能提升電池的短路電流、開路電 進^提升轉換效率1要說明的是，由於該金屬阻障 反康㈣紹之外的金屬製成’並且選用不易與該介電層3 反應的材料，因此該金屬_層5不會對該介電層3造成 9 201248874 破壞 而且本發明以金屬材質製成該金屬阻障層5,目的在於 利:金屬的導電性，使該介電層3的表面形成有可導電的 金屬膜，如此一來，比起使用無法導電的阻障層，本發明 可導電的金屬阻㈣5能與該導電膠層6配合，提升電池 的導電特性，it而提升電能輸出效果。此外，該金屬阻障 層5具有良好的光反射效果，可以增加電池背面長波段的 反射，將部分直接通過該^ 2而未被㈣的光線再度反 射回該晶ϋ 2使用，可提升光線利用率、有效地增益電流 、提升光電轉換效率。 閱圖2 5 ’本發明具有背電場結構的太陽能電池的 製造方法之第二較佳實施例’同樣用於製作圖2的太陽能 電池’但本實施例的步驟改良主要在於：當該介電層3及 該，屬阻障層5形成後，先不形成所述穿槽％及穿孔51， 而是直接在連續完整的金屬轉$ 5的表面披覆該導電膠 6’ ’並利用雷射焊接方式作局部焊接，其具體方式是利用雷 射光照射該導電膠6’❾狀職，導f膠6,之照光部位形 成高溫，該部位的材时擴散進入該金屬阻障I 5及該介 電層3’進而使該金屬阻障層5形成所述穿孔51，並使該 介電層3形成所述穿槽33 ^最後同樣利用高溫燒結之熱處 理，即可形成所述背電場結構4。 淮以上所述者，僅為本發明之較佳實施例而已，當不 能以此限定本發明實施之範圍，即大凡依本發明申請專利 範圍及發明說明内容所作之簡單的等效變化與修飾，皆仍 10 201248874 屬本發明專利涵蓋之範圍内。 【圖式簡單說明】 • 圖1是一種已知太陽能電池的製造流程示意圖； 圖2是一剖視示意圖，顯示本發明具有背電場結構的 太陽能電池的一較佳實施例； 圖3疋μ耘方塊圖，顯示本發明具有背電場結構的 太陽能電池的製造方法的一第一較佳實施例； 圖4是該第-較佳實施例各步驟進行時的流程示意圖 ;及 圖是/瓜程不思圖，顯示本發明具有背電場結構的 太陽能電池的製造方法的一第二較佳實施例。 11 201248874 【主要元件符號說明】 2…… -----曰a片 4 ......... •者電％結構 21 ···.. .....入光面 5 ......... •金屬阻障層 22····· •…背面 51........ •穿孔 23..... —基板 6 ......... •導電膠層 3…… —介電層 61........ •表層部 31 —第 面 62........ •導電接觸部 32····· —第一面 6’ ........ •導電膠 33..... …·穿槽 71 〜75 . •步驟 12Si〇2/SiNX, Al2〇3/SlN-^^3; ^ reduces surface defects' and thereby reduces the rate at which the carrier is on the back side of the wafer 2 201248874 (recombination), improving the conversion efficiency of the battery. The back electric field structure 4 is formed on the back surface 22 of the wafer 2 corresponding to the through groove 33. The back electric field structure 4 of the present embodiment is an A1_Si hybrid material, which is a carrier greater than a p_ substrate. A p-type semiconductor layer (also referred to as a p+ layer) having a carrier concentration of 23, by which an electric field acts to block electrons from moving toward the back surface 22 of the wafer 2, so that electrons are collected in the n-type emitter layer of the wafer 2. Therefore, the (4) field junction #4 can improve the carrier collection efficiency and conversion efficiency. It should be noted that when the substrate 23 of the wafer 2 is an n-type substrate, the back electric field structure 4 must be an n-type semiconductor layer (n+ layer) having a carrier concentration greater than that of the substrate 23. The metal barrier layer 5 is disposed on the second surface 32 of the dielectric layer 3, and has a plurality of through-holes corresponding to the dielectric layer 3, and the metal barrier layer 5 The thickness is about 1G nanometer (nm) to 1 () micrometer ((4), which can provide a good effect of protecting the dielectric layer 3, as well as good electrical conductivity and light reflection. The material of the metal barrier layer 5 is silver ( Ag), called M〇), titanium tungsten alloy (Tiw), tungsten (w), titanium (f), chromium (Cr), molybdenum alloy (M〇w), platinum (Pt), gold (Au), nickel (Ni Or, in combination with any of the above, the selection of such materials is mainly to form the metal barrier layer 5 into a conductive, dense film. The material of the conductive adhesive layer 6 of the present embodiment is aluminum or an aluminum alloy, such as a silver-aluminum alloy, an aluminum-bismuth alloy, but is not limited thereto, and includes a surface on the surface of the metal barrier layer 5 and a thickness of about 1. a surface portion 61 of 〇#m~5〇//m, and a plurality of conductive contact portions 62 spaced apart from each other and protruding from the surface layer portion 61 toward the through-hole si and the through-groove 33, the conductive contact portion 62 contacting 201248874 The electric field structure 4 is backed to form an electrical connection. 2, 3, and 4, a first preferred embodiment of a method for fabricating a solar cell having a back electric field structure according to the present invention comprises: (1) stepping in step 71: using, for example, a film of wire material, on the wafer 2 The back surface 22 is plated with a continuous and complete dielectric layer 3 which, as described above, is an oxide film, a nitride film or a composite of an oxide and a nitride. Of course, the wafer 2 can also be formed into a desired layer beforehand. For example, it is necessary to form an n-type emitter layer on the p-type (four) substrate 23 by a diffusion process and to form an anti-reflection film by a vacuum ore film method. Since the process of the wafer 2 itself is not an improvement of the present invention, it will not be described. (2) Step 72: The metal barrier layer 5 is coated on the second surface 32 of the "Xuan" electric layer 3 by a vacuum coating method such as vapor deposition or sputtering, and the material thereof is a metal material as described above. No longer stated. (3) Step 73: forming the through-holes 33 on the dielectric layer 3 and the metal barrier layer 5 to form the through-holes 51. This step may be performed by laser ablation. The portion of the metal barrier layer 5 is irradiated with laser light. Then, the light-emitting portion of the metal barrier layer 5 and the corresponding portion of the dielectric layer 3 are etched and removed to form the through-hole 51 and the through-hole %. Alternatively, a screen printing machine can be used to apply a money-etching paste on the partial surface of the δH metal barrier layer 5, and then the (4) glue can be removed by washing with water or a corresponding liquid. Thereafter, the local portion of the metal barrier layer 5 and the corresponding portion of the dielectric layer 3 - and (4) can be removed to form the through hole 51 and the through hole 33. 8 201248874 (4) Performing step 74: coating a surface of the metal barrier layer 5 with a conductive paste 6''. The conductive paste 6' of the present embodiment is a paste-like aluminum paste which can be screen priming or The ink jet pdnting method is applied by coating, and part of the material of the conductive paste 6 ′ is also filled and filled in the through holes 51 and the through grooves 33 to become the conductive contact portions 62 of the conductive adhesive layer 6 . (5) Step 75: The wafer 2 is subjected to heat treatment such as treatment, and the conductive paste 6 is dried and solidified into the conductive paste layer 6. The heat treatment described in the present embodiment is a high-temperature sintering (1), and during the heat treatment, the conductive paste 6 located in the through-groove 33 is diffused into the wafer from the back surface 22 of the crucible 2 2, aluminum is doped in the substrate 23 of the wafer 2 to be combined with the germanium of the substrate 23, so that the wafer 2 forms the back electric field structure* at the back surface 22 and at a position corresponding to the through-groove 33. The conductive contact portion 62 of the conductive adhesive layer 6 may be elongated, dot-like or other shape H. The predetermined shape is formed when the through-groove 33 and the through-hole 51 are formed, so that the conductive contact portion 62 also has a predetermined shape. According to the invention, before the conductive adhesive layer 6 is formed, the metal resist P early layer is formed as a barrier of the dielectric & 3 surface, and the metal barrier layer is used to form a dense film. Preventing the material of the conductive paste 6' from diffusing into the dielectric layer 3 during the sintering process, avoiding the conductive adhesive 6, causing damage to the layer: 3, having a good quality and a good drop: the carrier recombination rate Efficacy, can improve the short-circuit current of the battery, open circuit, and improve the conversion efficiency. 1 It should be noted that the metal is made of metal other than the metal barrier and the material that is not easily reacted with the dielectric layer 3 is selected. Therefore, the metal layer 5 does not cause damage to the dielectric layer 3 9 201248874 and the metal barrier material 5 is made of the metal material in order to facilitate the conductivity of the metal to make the dielectric layer 3 The surface is formed with a conductive metal film. Thus, the conductive metal resistor (4) 5 of the present invention can be combined with the conductive adhesive layer 6 to enhance the conductive property of the battery, and to enhance the electrical energy, compared to the use of a barrier layer that is not electrically conductive. Output effect. In addition, the metal barrier layer 5 has a good light reflection effect, can increase the reflection of the long wavelength band on the back side of the battery, and directly passes the portion of the light without the (4) light back to the wafer 2 to improve the light utilization. Rate, effectively gain current, and improve photoelectric conversion efficiency. 2] The second preferred embodiment of the method for fabricating a solar cell having a back electric field structure of the present invention is also used to fabricate the solar cell of FIG. 2, but the steps of the embodiment are improved mainly in that the dielectric layer 3 and this, after the formation of the barrier layer 5, the groove % and the through hole 51 are not formed first, but the conductive paste 6' ' is directly coated on the surface of the continuous complete metal turn $ 5 and is laser welded. The method is local welding, and the specific method is to irradiate the conductive adhesive with a laser light, and the light-emitting portion forms a high temperature, and the material of the portion diffuses into the metal barrier I 5 and the dielectric. The layer 3' further causes the metal barrier layer 5 to form the through-hole 51, and the dielectric layer 3 forms the through-groove 33. Finally, the back-field structure 4 is formed by heat treatment also by high-temperature sintering. The above is only the preferred embodiment of the present invention, and is not intended to limit the scope of the invention, that is, the simple equivalent changes and modifications made by the scope of the invention and the description of the invention, All remain 10 201248874 within the scope of the invention patent. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a schematic view showing a manufacturing process of a known solar cell; Fig. 2 is a cross-sectional view showing a preferred embodiment of a solar cell having a back electric field structure of the present invention; A block diagram showing a first preferred embodiment of a method for fabricating a solar cell having a back electric field structure according to the present invention; and FIG. 4 is a flow chart showing the steps of the first preferred embodiment; A second preferred embodiment of a method of fabricating a solar cell having a back electric field structure of the present invention is shown. 11 201248874 [Explanation of main component symbols] 2... -----曰a slice 4 ......... • Power % structure 21 ···.. ..... ........ • Metal barrier layer 22····· •...Back 51........ •Perforation 23..... —Substrate 6 ........ • Conductive adhesive layer 3... - Dielectric layer 61........ • Surface layer portion 31 - First surface 62........ • Conductive contact portion 32····· - First Face 6' ........ • Conductive adhesive 33.....·through slot 71~75. • Step 12