TW201709544A - Method for producing solar cell - Google Patents

Method for producing solar cell Download PDF

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TW201709544A
TW201709544A TW105102325A TW105102325A TW201709544A TW 201709544 A TW201709544 A TW 201709544A TW 105102325 A TW105102325 A TW 105102325A TW 105102325 A TW105102325 A TW 105102325A TW 201709544 A TW201709544 A TW 201709544A
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impurity diffusion
type impurity
concentration
solar cell
layer
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TW105102325A
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TWI604627B (en
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小林裕美子
綿引達郎
西村邦彦
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三菱電機股份有限公司
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    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E10/00—Energy generation through renewable energy sources
    • Y02E10/50—Photovoltaic [PV] energy
    • Y02E10/547—Monocrystalline silicon PV cells
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
    • Y02P70/50—Manufacturing or production processes characterised by the final manufactured product

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Abstract

An objective of this invention is to obtain a producing method for a solar cell, the method forms an electrode self-alignmently on a high-concentrated impurity diffusion layer and maximizes passivation effect of a passivation film, and exchange efficiency is high. The method of this invention contains: forming a backside dielectric layer 109 on a n-type monocrystalline silicon substrate 100 and a high-concentrated n-type impurity diffusion source 106, and then leaving out the high-concentrated n-type impurity diffusion source 106 and the backside dielectric layer 109 on the high-concentrated n-type impurity diffusion source 106 together, forming an opening h. And then, forming a negative electrode 113 contacted with a high-concentrated n-type impurity diffusion layer 107 in the opening h. Providing oxygen in or prior to the step of diffusing a n-type impurity from the n-type impurity diffusion source 106, forming the high-concentrated n-type impurity diffusion layer 107, and forming a hot-oxide film 108 in an area without the formation of n-type impurity diffusion source 106.

Description

太陽電池之製造方法 Solar cell manufacturing method

本發明係關於太陽電池之製造方法，尤其關於背面或受光面接觸(contact)之技術。 The present invention relates to a method of manufacturing a solar cell, and more particularly to a technique of contacting a back surface or a light receiving surface.

過去，一般的結晶矽太陽電池係具備有：半導體基板；由與半導體基板不同導電型的擴散層所構成，形成pn接面之射極(emitter)層；形成於射極層上之抗反射層；與半導體基板相同導電型之背面電場層；以及分別與射極層及背面電場層連接之電極。 In the past, a general crystallization solar cell system includes a semiconductor substrate, a diffusion layer formed of a conductivity type different from the semiconductor substrate, an emitter layer forming a pn junction, and an antireflection layer formed on the emitter layer. a back surface electric field layer of the same conductivity type as the semiconductor substrate; and an electrode connected to the emitter layer and the back surface electric field layer, respectively.

若考慮的是電極的接觸電阻，則以提高位於電極下之擴散層的雜質濃度為佳。另一方面，若是要減少在擴散層內之少數載子(carrier)的再結合，得到高開路電壓(open circuit voltage)，卻又以降低擴散層的雜質濃度為佳。因此，已知有一種選擇性地將電極下摻雜(dope)成高濃度，將電極下的區域以外的區域摻雜成低濃度之選擇摻雜結構。 If the contact resistance of the electrode is considered, it is preferable to increase the impurity concentration of the diffusion layer located under the electrode. On the other hand, if the recombination of a minority carrier in the diffusion layer is to be reduced, a high open circuit voltage is obtained, but the impurity concentration of the diffusion layer is preferably lowered. Therefore, a selective doping structure in which a region is selectively doped to a high concentration and a region other than the region under the electrode is doped to a low concentration is known.

形成如前述的選擇摻雜結構之方法，有例如：在電極下的區域印刷塗佈具有高雜質濃度的摻雜劑糊(dopant paste)，再進行熱擴散以形成高濃度擴散層之後， 實施濕式蝕刻(wet etching)將摻雜劑糊及在熱擴散中形成的玻璃(glass)予以去除掉之方法。但是，將摻雜劑糊去除掉後，就不易識別高濃度擴散層及低濃度擴散層，而難以將電極對準形成在高濃度擴散層上。電極從高濃度擴散層上偏離，就會造成接觸電阻之增大或開路電壓之降低。因此，必須要有抑制電極的位置偏離，防止特性降低之措施。 A method of forming a doping structure as described above, for example, after printing a dopant paste having a high impurity concentration on a region under the electrode, and then performing thermal diffusion to form a high concentration diffusion layer, A method of removing the dopant paste and the glass formed in the thermal diffusion by wet etching is performed. However, after the dopant paste is removed, it is difficult to recognize the high concentration diffusion layer and the low concentration diffusion layer, and it is difficult to form the electrodes on the high concentration diffusion layer. Deviation of the electrode from the high concentration diffusion layer causes an increase in contact resistance or a decrease in open circuit voltage. Therefore, it is necessary to have a measure for suppressing the positional deviation of the electrode and preventing the characteristic from being lowered.

例如，專利文獻1係利用可藉由進行燒製使其表面形成凹部之擴散層形成組成物，來形成高濃度的雜質擴散層(亦即高濃度擴散層)。因為可使高濃度擴散層的表面形成凹部，所以與低濃度擴散層之識別會變容易，而可抑制電極的位置偏離。 For example, Patent Document 1 forms a high-concentration impurity diffusion layer (that is, a high-concentration diffusion layer) by forming a composition by a diffusion layer on which a concave portion is formed by firing. Since the surface of the high-concentration diffusion layer can be formed into a concave portion, the identification with the low-concentration diffusion layer becomes easy, and the positional deviation of the electrode can be suppressed.

專利文獻2係在結晶矽基板上形成膜厚較厚的低濃度摻雜劑擴散源及膜厚較薄的高濃度摻雜劑擴散源，然後進行擴散。接著進行濕式蝕刻，對於厚膜的低濃度摻雜劑擴散源完全不加以去除(亦即留下)，只將薄膜的高濃度摻雜劑擴散源完全去除掉，以形成開口。因為可自對準地進行接觸開口及電極之形成，所以無需進行電極之對位，不會發生電極之位置偏離。 Patent Document 2 discloses that a low-concentration dopant diffusion source having a large thickness and a high-concentration dopant diffusion source having a small thickness are formed on a crystalline germanium substrate, and then diffused. Next, a wet etch is performed, and the low-concentration dopant diffusion source for the thick film is not removed at all (ie, left), and only the high-concentration dopant diffusion source of the film is completely removed to form an opening. Since the contact opening and the electrode can be formed in a self-aligned manner, it is not necessary to perform alignment of the electrodes, and the positional deviation of the electrodes does not occur.

[先前技術文獻] [Previous Technical Literature] (專利文獻) (Patent Literature)

(專利文獻1)WO 2013/015173號公報 (Patent Document 1) WO 2013/015173

(專利文獻2)日本特開2012-114452號公報 (Patent Document 2) Japanese Patent Laid-Open Publication No. 2012-114452

上述專利文獻1之方法，因為定位的精度取決於印刷機或糊(paste)的特性等之外在的因素，所以有：對於例如寬度100μm以下之微細的圖案(pattern)要維持精度很困難之問題。另外，為了確實在擴散層上形成電極，必須將位於電極下之擴散層的寬度形成得比電極的寬度寬。因此，高濃度擴散層的表面積會增加，少數載子之再結合會增多。 In the method of Patent Document 1, since the accuracy of positioning depends on factors other than the characteristics of a printer or a paste, it is difficult to maintain accuracy for a fine pattern of, for example, a width of 100 μm or less. problem. Further, in order to surely form an electrode on the diffusion layer, it is necessary to form the width of the diffusion layer under the electrode to be wider than the width of the electrode. Therefore, the surface area of the high concentration diffusion layer increases, and the recombination of a few carriers increases.

專利文獻2之方法係使摻雜劑擴散源在摻雜劑擴散後變化為介電質層，且使未開口的部分殘留作為鈍化膜。因此，不能自由選擇鈍化(passivation)膜。而且，由摻雜劑擴散源變成的介電質層因為經歷過摻雜劑擴散時的高溫，所以有膜質會降低之虞，無法使鈍化效果發揮到最大限度。 In the method of Patent Document 2, the dopant diffusion source is changed to a dielectric layer after the dopant is diffused, and a portion which is not opened remains as a passivation film. Therefore, the passivation film cannot be freely selected. Further, since the dielectric layer formed by the dopant diffusion source experiences a high temperature at the time of diffusion of the dopant, the film quality is lowered, and the passivation effect cannot be maximized.

本發明係鑑於上述的課題而完成者，其目的在得到一種在高濃度的雜質擴散層上自對準地形成電極，使鈍化膜的鈍化效果發揮到最大限度，轉換效率高之太陽電池之製造方法。 The present invention has been made in view of the above-described problems, and an object thereof is to provide a solar cell manufacturing method in which an electrode is formed in a self-aligned manner on a high-concentration impurity diffusion layer, a passivation effect of a passivation film is maximized, and conversion efficiency is high. method.

為了解決上述課題，達成本發明的目的，本發明係在具有第一導電型之結晶系的半導體基板的第一主面上的一部分形成含有第一導電型的雜質之擴散源，然後使第一導電型的雜質從擴散源擴散到半導體基板中。在擴散工序前或擴散工序中供給氧，在未形成擴散源之區域 形成熱氧化膜。形成第一雜質擴散層，並在半導體基板上及擴散源上形成介電質層後，將擴散源與位於擴散源上之介電質層一起掀離(lift-off)，形成開口，形成在該開口內與第一雜質擴散層接觸(contact)之電極。 In order to solve the above problems, an object of the present invention is to provide a diffusion source containing impurities of a first conductivity type in a part of a first main surface of a semiconductor substrate having a first conductivity type crystal, and then to make a first Conductive impurities diffuse from the diffusion source into the semiconductor substrate. Supply oxygen before or during the diffusion process, in areas where no diffusion source is formed A thermal oxide film is formed. After forming the first impurity diffusion layer and forming a dielectric layer on the semiconductor substrate and the diffusion source, the diffusion source is lifted off together with the dielectric layer on the diffusion source to form an opening. An electrode in the opening that is in contact with the first impurity diffusion layer.

根據本發明，在屬於高濃度雜質擴散層之第一雜質擴散層上自對準地形成電極，並將擴散前或擴散中形成之熱氧化膜、與擴散後形成之介電質層的積層結構體用作為鈍化膜，所以會產生可得到使鈍化效果發揮到最大限度，轉換效率高之太陽電池之製造方法的效果。 According to the present invention, an electrode is formed in a self-aligned manner on a first impurity diffusion layer belonging to a high-concentration impurity diffusion layer, and a thermal oxide film formed before diffusion or diffusion and a laminated structure of a dielectric layer formed after diffusion Since the body is used as a passivation film, there is an effect that a solar cell manufacturing method which maximizes the passivation effect and has high conversion efficiency can be obtained.

100‧‧‧n型單晶矽基板 100‧‧‧n type single crystal germanium substrate

100A‧‧‧受光面 100A‧‧‧Glossy surface

100B‧‧‧背面 100B‧‧‧back

101‧‧‧BSG膜 101‧‧‧BSG film

102‧‧‧NSG膜 102‧‧‧NSG film

103‧‧‧p型雜質擴散層 103‧‧‧p type impurity diffusion layer

104‧‧‧低濃度n型雜質擴散層 104‧‧‧Low concentration n-type impurity diffusion layer

105‧‧‧PSG膜 105‧‧‧PSG film

106‧‧‧高濃度n型雜質擴散源 106‧‧‧High concentration n-type impurity diffusion source

107‧‧‧高濃度n型雜質擴散層 107‧‧‧High concentration n-type impurity diffusion layer

108‧‧‧熱氧化膜 108‧‧‧ Thermal Oxide Film

109‧‧‧背面側介電質層 109‧‧‧Back side dielectric layer

109a‧‧‧高濃度n型雜質擴散源上以外之背面側介電質層 109a‧‧‧ Back side dielectric layer other than high concentration n-type impurity diffusion source

109b‧‧‧高濃度n型雜質擴散源上之背面側介電質層 109b‧‧‧Backside dielectric layer on a high concentration n-type impurity diffusion source

110‧‧‧受光面側介電質層 110‧‧‧Lighted side dielectric layer

111‧‧‧抗反射膜 111‧‧‧Anti-reflective film

112‧‧‧正電極 112‧‧‧ positive electrode

113‧‧‧負電極 113‧‧‧Negative electrode

200‧‧‧p型單晶矽基板 200‧‧‧p type single crystal germanium substrate

201‧‧‧PSG膜 201‧‧‧PSG film

202‧‧‧NSG膜 202‧‧‧NSG film

203‧‧‧n型雜質擴散層 203‧‧‧n type impurity diffusion layer

204‧‧‧低濃度p型雜質擴散層 204‧‧‧Low concentration p-type impurity diffusion layer

205‧‧‧p型雜質擴散源 205‧‧‧p type impurity diffusion source

206‧‧‧高濃度p型雜質擴散源 206‧‧‧High concentration p-type impurity diffusion source

207‧‧‧高濃度p型雜質擴散層 207‧‧‧High concentration p-type impurity diffusion layer

208‧‧‧熱氧化膜 208‧‧‧ Thermal Oxide Film

209‧‧‧背面側介電質層 209‧‧‧Back side dielectric layer

209a‧‧‧高濃度p型雜質擴散源上以外之背面側介電質層 209a‧‧‧ Backside dielectric layer other than the high concentration p-type impurity diffusion source

209b‧‧‧高濃度p型雜質擴散源上之背面側介電質層 209b‧‧‧ Back side dielectric layer on a high concentration p-type impurity diffusion source

210‧‧‧介電質層 210‧‧‧ dielectric layer

211‧‧‧抗反射膜 211‧‧‧Anti-reflective film

212‧‧‧負電極 212‧‧‧Negative electrode

213‧‧‧正電極 213‧‧‧ positive electrode

h‧‧‧開口 H‧‧‧ openings

S100至S107、S100s、S200至S207‧‧‧步驟 S100 to S107, S100s, S200 to S207‧‧ steps

第1圖係顯示以實施形態1之太陽電池之製造方法形成的太陽電池之圖，其中(a)為上視圖，(b)為(a)的A-A剖面圖。 Fig. 1 is a view showing a solar cell formed by the method for producing a solar cell according to the first embodiment, wherein (a) is a top view and (b) is an A-A cross-sectional view of (a).

第2圖係顯示實施形態1之太陽電池之製造方法之流程圖(flow chart)。 Fig. 2 is a flow chart showing a method of manufacturing a solar cell according to the first embodiment.

第3圖(a)至(c)係顯示實施形態1之太陽電池之製造方法之各工序剖面圖。 Fig. 3 (a) to (c) are cross-sectional views showing respective steps of a method of manufacturing a solar cell according to the first embodiment.

第4圖(a)至(c)係顯示實施形態1之太陽電池之製造方法之各工序剖面圖。 Fig. 4 (a) to (c) are cross-sectional views showing respective steps of a method for producing a solar cell according to the first embodiment.

第5圖係顯示以實施形態2之太陽電池之製造方法形成的太陽電池之圖。 Fig. 5 is a view showing a solar cell formed by the method for producing a solar cell according to the second embodiment.

第6圖係顯示實施形態2之太陽電池之製造方法之流 程圖。 Figure 6 is a flow chart showing the manufacturing method of the solar cell of the second embodiment. Cheng Tu.

第7圖(a)及(b)係顯示實施形態2之太陽電池之製造方法之各工序剖面圖。 Fig. 7 (a) and (b) are cross-sectional views showing respective steps of a method for producing a solar cell according to a second embodiment.

第8圖係顯示實施形態2之太陽電池之製造方法中的熱處理工序的溫度輪廓(profile)之圖。 Fig. 8 is a view showing a temperature profile of a heat treatment step in the method for producing a solar cell according to the second embodiment.

第9圖係顯示實施形態3之太陽電池之製造方法之流程圖。 Fig. 9 is a flow chart showing a method of manufacturing the solar cell of the third embodiment.

第10圖係顯示以實施形態4之太陽電池之製造方法形成的太陽電池之圖，其中(a)為上視圖，(b)為(a)的B-B剖面圖。 Fig. 10 is a view showing a solar cell formed by the method for producing a solar cell according to Embodiment 4, wherein (a) is a top view and (b) is a B-B cross-sectional view of (a).

第11圖係顯示實施形態4之太陽電池之製造方法之流程圖。 Fig. 11 is a flow chart showing a method of manufacturing the solar cell of the fourth embodiment.

第12圖(a)至(c)係顯示實施形態4之太陽電池之製造方法之各工序剖面圖。 Fig. 12 (a) to (c) are cross-sectional views showing respective steps of a method of manufacturing a solar cell according to a fourth embodiment.

第13圖(a)至(c)係顯示實施形態4之太陽電池之製造方法之各工序剖面圖。 Fig. 13 (a) to (c) are cross-sectional views showing respective steps of a method for producing a solar cell according to a fourth embodiment.

第14圖係顯示以實施形態5之太陽電池之製造方法形成的太陽電池之圖，其中(a)為上視圖，(b)為(a)的C-C剖面圖。 Fig. 14 is a view showing a solar cell formed by the method for producing a solar cell according to the fifth embodiment, wherein (a) is a top view and (b) is a C-C cross-sectional view of (a).

第15圖係顯示實施形態5之太陽電池之製造方法之流程圖。 Fig. 15 is a flow chart showing a method of manufacturing the solar cell of the fifth embodiment.

第16圖(a)至(c)係顯示實施形態5之太陽電池之製造方法之各工序剖面圖。 Fig. 16 (a) to (c) are cross-sectional views showing respective steps of a method of manufacturing a solar cell according to a fifth embodiment.

第17圖(a)至(c)係顯示實施形態5之太陽電池之製造 方法之各工序剖面圖。 Fig. 17 (a) to (c) show the manufacture of the solar cell of the fifth embodiment A cross-sectional view of each process of the method.

第18圖係顯示實施形態1之太陽電池的背面側之說明圖。 Fig. 18 is an explanatory view showing the back side of the solar cell of the first embodiment.

第19圖係顯示實施形態1之太陽電池的變形例的背面側之說明圖。 Fig. 19 is an explanatory view showing a back side of a modified example of the solar battery of the first embodiment.

以下，根據圖式來詳細說明本發明的實施形態之太陽電池之製造方法及太陽電池。但本發明並不限定於實施形態。 Hereinafter, a method of manufacturing a solar cell and a solar cell according to an embodiment of the present invention will be described in detail based on the drawings. However, the present invention is not limited to the embodiment.

實施形態1. Embodiment 1.

第1圖係顯示以本發明的實施形態1之太陽電池之製造方法形成的太陽電池之圖，其中(a)為上視圖，(b)為(a)的A-A剖面圖，第2圖係顯示實施形態1之太陽電池之製造方法之流程圖，第3圖(a)至(c)及第4圖(a)至(c)係顯示實施形態1之太陽電池之製造方法之各工序剖面圖。 Fig. 1 is a view showing a solar cell formed by the method for manufacturing a solar cell according to the first embodiment of the present invention, wherein (a) is a top view, (b) is an AA cross-sectional view of (a), and Fig. 2 is a view Fig. 3 is a flow chart showing a method of manufacturing a solar cell according to the first embodiment, and Figs. 3(a) to (c) and Figs. 4(a) to 4(c) are cross-sectional views showing respective steps of a method for manufacturing a solar cell according to the first embodiment. .

在全體說明之前，先說明本實施形態1之太陽電池之製造方法的要點。本實施形態1之太陽電池之製造程序，係如第1圖(a)及(b)所示，使用具有受光面100A及背面100B之n型單晶矽基板100來作為結晶系半導體基板。在n型單晶矽基板100的背面100B的預先決定的一部分的區域形成由含有高濃度的磷(phosphorus)之摻雜劑糊(dopant paste)所構成的高濃度n型雜質擴散源106來作為第一擴散源，然後使作為雜質之磷從高濃度n型雜質擴散 源106擴散來形成高濃度n型雜質擴散層107以作為第一雜質擴散層。其中，在高濃度n型雜質擴散源106的擴散工序中或擴散工序後供給氧，以在未形成高濃度n型雜質擴散源106之區域形成熱氧化膜108，然後，在熱氧化膜108及高濃度n型雜質擴散源106上形成氮化矽膜來作為背面側介電質層109。然後，將高濃度n型雜質擴散源106及位於其上的部分的背面側介電質層109b掀離(liftoff)而形成開口h。然後在該開口h形成負電極113。另外，在受光面100A側形成由柵電極(grid electrode)112G及匯流電極(bus electrode)112B所構成之正電極112。在背面100B側形成之上述的負電極113也是由與受光面側對應之柵電極及匯流電極所構成。 Prior to the entire description, the gist of the method for manufacturing a solar cell according to the first embodiment will be described. In the manufacturing procedure of the solar cell of the first embodiment, as shown in FIGS. 1(a) and 1(b), the n-type single crystal germanium substrate 100 having the light receiving surface 100A and the back surface 100B is used as the crystalline semiconductor substrate. A high-concentration n-type impurity diffusion source 106 composed of a dopant paste containing a high concentration of phosphorous is formed in a predetermined portion of the back surface 100B of the n-type single crystal germanium substrate 100 as a predetermined portion. a first diffusion source, and then diffusing phosphorus as an impurity from a high concentration n-type impurity The source 106 is diffused to form a high-concentration n-type impurity diffusion layer 107 as a first impurity diffusion layer. In the diffusion step of the high-concentration n-type impurity diffusion source 106 or after the diffusion step, oxygen is supplied to form the thermal oxide film 108 in a region where the high-concentration n-type impurity diffusion source 106 is not formed, and then the thermal oxide film 108 and A tantalum nitride film is formed on the high-concentration n-type impurity diffusion source 106 as the back side dielectric layer 109. Then, the high-concentration n-type impurity diffusion source 106 and the portion of the back surface-side dielectric layer 109b located thereon are lifted off to form an opening h. A negative electrode 113 is then formed at the opening h. Further, a positive electrode 112 composed of a grid electrode 112G and a bus electrode 112B is formed on the light-receiving surface 100A side. The above-described negative electrode 113 formed on the side of the back surface 100B is also composed of a gate electrode and a bus electrode corresponding to the light-receiving surface side.

本實施形態之太陽電池之製造方法，係在將作為第一擴散源之高濃度n型雜質擴散源106掀離而成為開口h之部分進行電極印刷，而可自對準地將負電極113形成在高濃度n型雜質擴散層107上，所以無需進行對位，可防止由於位置偏離所造成的特性降低。 In the method of manufacturing a solar cell according to the present embodiment, the electrode is printed by separating the high-concentration n-type impurity diffusion source 106 as the first diffusion source and opening the portion of the opening h, and the negative electrode 113 can be formed in a self-aligned manner. On the high-concentration n-type impurity diffusion layer 107, it is not necessary to perform alignment, and deterioration in characteristics due to positional deviation can be prevented.

相對於此，舉例來說，若如以往在使雜質從作為第一擴散源之高濃度n型雜質擴散源106擴散後將高濃度n型雜質擴散源106去除掉的話，就不易判別高濃度n型雜質擴散層107與其他的部分，而難以使電極的位置對準高濃度n型雜質擴散層107。而且，為了防止位置偏離必須將高濃度n型雜質擴散層107形成得比負電極113寬。 On the other hand, if the high-concentration n-type impurity diffusion source 106 is removed by diffusing impurities from the high-concentration n-type impurity diffusion source 106 as the first diffusion source, it is difficult to discriminate the high concentration n. The type impurity diffusion layer 107 and other portions make it difficult to align the position of the electrode with the high concentration n-type impurity diffusion layer 107. Moreover, the high-concentration n-type impurity diffusion layer 107 must be formed wider than the negative electrode 113 in order to prevent positional deviation.

根據上述製造方法的話，則從厚度方向看n型單晶矽基板100時的開口h的大小及形狀會與高濃度n型雜質擴散層107的大小及形狀相同。亦即，負電極113會不偏不倚地自對準地接觸在高濃度n型雜質擴散層107上，所以與將高濃度n型雜質擴散層107形成在比負電極113寬的區域之情況相比較，較可抑制由氮化矽膜所構成之背面側介電質層109a及高濃度n型雜質擴散層107間之少數載子的再結合。結果，就可預期會有太陽電池特性之提高。以上雖然將背面側介電質層109予以區分而分別記載為n型雜質擴散源106上的背面側介電質層109b、及以外的區域上的背面側介電質層109a，但有時亦將以外的區域上的背面側介電質層109a簡稱為背面側介電質層109。 According to the above-described manufacturing method, the size and shape of the opening h when the n-type single crystal germanium substrate 100 is viewed from the thickness direction are the same as the size and shape of the high-concentration n-type impurity diffusion layer 107. That is, the negative electrode 113 is in self-aligned contact with the high-concentration n-type impurity diffusion layer 107 without bias, so that the high-concentration n-type impurity diffusion layer 107 is formed in a region wider than the negative electrode 113. By comparison, recombination of a minority carrier between the back side dielectric layer 109a composed of the tantalum nitride film and the high concentration n type impurity diffusion layer 107 can be suppressed. As a result, an increase in solar cell characteristics can be expected. In the above description, the back side dielectric layer 109 is divided into the back side dielectric layer 109b on the n-type impurity diffusion source 106 and the back side dielectric layer 109a in the other areas. The back side dielectric layer 109a on the other areas is simply referred to as the back side dielectric layer 109.

第1圖中雖未顯示背面匯流電極，但受光面匯流電極112B與背面匯流電極係設成相對應，且背面匯流電極係比受光面匯流電極112B寬。形成為如此的構成，就可在利用連接引線來連接複數個太陽電池單元(cell)的受光面側匯流電極112B與背面側匯流電極，以形成太陽電池模組(module)之際，有效率地進行連接。 Although the back surface bus electrode is not shown in FIG. 1, the light-receiving surface bus electrode 112B is provided to correspond to the back surface bus electrode, and the back surface bus electrode is wider than the light-receiving surface bus electrode 112B. With such a configuration, it is possible to efficiently connect the light-receiving surface side bus electrode 112B and the back side side bus electrode of a plurality of solar battery cells by a connecting lead to form a solar cell module. Make a connection.

另外，亦可在未形成第一雜質擴散層之部位，形成低濃度的n型雜質擴散層104來作為雜質濃度比第一雜質擴散層低之第二雜質擴散層。在介電質層的鈍化效果不充分之情況，利用第二雜質擴散層的電場效果使少數載子遠離結晶系半導體基板表面，表面再結合之情形就會受到抑制，太陽電池特性就會提高。 Further, a low-concentration n-type impurity diffusion layer 104 may be formed as a second impurity diffusion layer having a lower impurity concentration than the first impurity diffusion layer at a portion where the first impurity diffusion layer is not formed. In the case where the passivation effect of the dielectric layer is insufficient, the electric field effect of the second impurity diffusion layer is such that a minority carrier is away from the surface of the crystalline semiconductor substrate, and the surface recombination is suppressed, and the solar cell characteristics are improved.

就未供給氧之製程(process)而言，雜質會擴散到比形成高濃度n型雜質擴散源106之區域多寬數十μm之區域，反之，如上述在到達擴散溫度之前導入氧氣，則會在未以高濃度n型雜質擴散源106，亦即含有高濃度的磷之摻雜劑糊加以覆蓋之基板表面形成熱氧化膜108。由於氧氣之導入而形成之熱氧化膜108會發揮阻障(barrier)層之作用，大幅抑制雜質擴散到形成有高濃度n型雜質擴散源106之區域以外的區域。結果，就可抑制高濃度n型雜質擴散層107之擴大，使之以較窄的寬度形成，且低濃度n型雜質擴散層104的均一性及穩定性提高。形成的熱氧化膜108除了發揮阻障膜的作用之外，也會吸收在低濃度n型雜質擴散層104的表面附近偏析出的磷而使表面濃度降低，所以會使n型單晶矽基板100或低濃度n型雜質擴散層104表面的再結合速度減低，開路電壓就會提高。 In the case of a process in which oxygen is not supplied, impurities are diffused to a region which is several tens of μm wider than a region where the high-concentration n-type impurity diffusion source 106 is formed, and conversely, if oxygen is introduced before reaching the diffusion temperature, The thermal oxide film 108 is formed on the surface of the substrate which is not covered with the high-concentration n-type impurity diffusion source 106, that is, the dopant paste containing a high concentration of phosphorus. The thermal oxide film 108 formed by the introduction of oxygen acts as a barrier layer, and greatly suppresses diffusion of impurities into a region other than the region where the high-concentration n-type impurity diffusion source 106 is formed. As a result, the enlargement of the high-concentration n-type impurity diffusion layer 107 can be suppressed to be formed with a narrow width, and the uniformity and stability of the low-concentration n-type impurity diffusion layer 104 can be improved. In addition to the function of the barrier film, the formed thermal oxide film 108 also absorbs phosphorus which is segregated in the vicinity of the surface of the low-concentration n-type impurity diffusion layer 104 to lower the surface concentration, so that the n-type single crystal germanium substrate is made. The recombination speed of the surface of 100 or the low-concentration n-type impurity diffusion layer 104 is lowered, and the open circuit voltage is increased.

在實施形態1之工序中，在熱氧化膜108形成後並不另外進行雜質擴散等，而從上方形成介電質層，而成為以介電質層加以覆蓋的形式。因此，不會使雜質擴散到熱氧化膜108內，可維持鈍化效果。如此，在有於高濃度n型雜質擴散源106的擴散工序中進行氧化之情況，只要在升溫工序中導入氧氣，就可同時形成高濃度n型雜質擴散層107及熱氧化膜108，所以不用增加工數，就可形成由熱氧化膜及介電質層的積層結構所構成之鈍化膜。 In the step of the first embodiment, after the thermal oxide film 108 is formed, the impurity layer is not separately diffused, and the dielectric layer is formed from above, and is covered with a dielectric layer. Therefore, the impurities are not diffused into the thermal oxide film 108, and the passivation effect can be maintained. In the case where oxidation is performed in the diffusion step of the high-concentration n-type impurity diffusion source 106, if the oxygen is introduced in the temperature increasing step, the high-concentration n-type impurity diffusion layer 107 and the thermal oxide film 108 can be simultaneously formed, so that it is not necessary. By increasing the number of work, a passivation film composed of a laminated structure of a thermal oxide film and a dielectric layer can be formed.

此處，在低濃度n型雜質擴散層104上或背 面100B上形成熱氧化膜此一工序，亦可在高濃度n型雜質擴散層107形成後進行。不過，在高濃度n型雜質擴散層107形成後進行氧化，氧會從高濃度n型雜質擴散源106與背面100B之間的很小的間隙進入，使特別是高濃度n型雜質擴散層107的表面會快速氧化，而會有高濃度n型雜質擴散層107的表面濃度降低之情形。如此一來，高濃度n型雜質擴散層107與背面電極的接觸電阻會增大，而有造成填充因子(Fill Factor；F.F.)特性降低之虞。 Here, on the low concentration n-type impurity diffusion layer 104 or on the back The step of forming a thermal oxide film on the surface 100B may be performed after the formation of the high-concentration n-type impurity diffusion layer 107. However, oxidation is performed after the formation of the high-concentration n-type impurity diffusion layer 107, and oxygen enters from a small gap between the high-concentration n-type impurity diffusion source 106 and the back surface 100B, so that the high-concentration n-type impurity diffusion layer 107 is particularly high. The surface is rapidly oxidized, and the surface concentration of the high-concentration n-type impurity diffusion layer 107 is lowered. As a result, the contact resistance of the high-concentration n-type impurity diffusion layer 107 and the back electrode is increased, and the factor of the Fill Factor (F.F.) is lowered.

另一方面，在高濃度n型雜質擴散層107形成前或形成中進行氧化的話，即使高濃度n型雜質擴散源106正下方受到一些氧化，也可藉由之後之來自高濃度n型雜質擴散源106之擴散而充分供給磷，所以不會發生所形成的高濃度n型雜質擴散層107的表面濃度降低之情形。 On the other hand, if oxidation is performed before or during formation of the high-concentration n-type impurity diffusion layer 107, even if some of the high-concentration n-type impurity diffusion source 106 is subjected to some oxidation, it can be diffused from the high-concentration n-type impurity. Since the source 106 is diffused and the phosphorus is sufficiently supplied, the surface concentration of the formed high-concentration n-type impurity diffusion layer 107 does not decrease.

又，背面側介電質層109可在使雜質從高濃度n型雜質擴散源106擴散後形成，所以背面側介電質層109不需具有900℃以上之高溫耐性。因此，可廣範圍地採用各種材料來作為背面側介電質層109，可最大限度地得到鈍化效果。其中，作為第一擴散源之由含有磷之摻雜劑糊所構成之高濃度n型雜質擴散源106較佳為與n型單晶矽基板100直接相接。或者，亦可與n型單晶矽基板100之間夾著很薄之5nm以下的氧化矽膜等之介電質層。第一擴散源與結晶系半導體基板之間若形成有很厚的介電質層，從第一擴散源擴散之雜質就不會充分擴散到結晶系半 導體基板內，難以得到希望的表面雜質濃度及擴散深度。 Further, since the back side dielectric layer 109 can be formed by diffusing impurities from the high concentration n-type impurity diffusion source 106, the back side dielectric layer 109 does not need to have a high temperature resistance of 900 ° C or higher. Therefore, various materials can be widely used as the back side dielectric layer 109, and the passivation effect can be maximized. Among them, the high-concentration n-type impurity diffusion source 106 composed of a phosphorus-containing dopant paste as the first diffusion source is preferably in direct contact with the n-type single crystal germanium substrate 100. Alternatively, a dielectric layer such as a ruthenium oxide film having a thickness of 5 nm or less may be interposed between the n-type single crystal germanium substrate 100. If a thick dielectric layer is formed between the first diffusion source and the crystalline semiconductor substrate, impurities diffused from the first diffusion source are not sufficiently diffused into the crystal system half. In the conductor substrate, it is difficult to obtain a desired surface impurity concentration and diffusion depth.

使第一擴散源及位於第一擴散源上的部分的介電質層掀離之方法，可採用濕式蝕刻或雷射照射。採用濕式蝕刻，可同時蝕刻作為受光面側的擴散源之BSG(硼矽酸鹽玻璃：Boron Silicate Glass)膜等之膜，操作性良好。此外，在後面的實施形態3中也會說明，進行雷射照射之情況，可容易地實現蝕刻耐性低之介電質層的開口。 The method of separating the first diffusion source and the portion of the dielectric layer on the first diffusion source may be wet etching or laser irradiation. By wet etching, a film such as a BSG (Boron Silicate Glass) film which is a diffusion source on the light-receiving surface side can be simultaneously etched, and the workability is good. Further, in the third embodiment to be described later, it is also possible to easily realize the opening of the dielectric layer having low etching resistance in the case of performing laser irradiation.

以下，參照附隨的圖式來詳細說明本發明之太陽電池之製造方法的實施形態。第3圖(a)至(c)及第4圖(a)至(c)係顯示實施形態1之太陽電池的製造程序之各工序剖面圖。 Hereinafter, embodiments of the method for manufacturing a solar cell of the present invention will be described in detail with reference to the accompanying drawings. Fig. 3 (a) to (c) and Fig. 4 (a) to (c) are cross-sectional views showing respective steps of a manufacturing procedure of the solar cell of the first embodiment.

首先，準備n型單晶矽基板100。結晶矽基板係以利用線鋸(wire saw)等之機械的切斷法來切割(cut)矽錠(silicon ingot)將之切片(slice)而製造出，所以表面會殘存有污染或損傷(damage)。因此，以使用氫氧化鈉(sodium hydroxide)溶液等的鹼性(alkali)溶液之濕式蝕刻程序，來去除掉存在於n型單晶矽基板100的表面之損傷層。然後，在n型單晶矽基板100的表面形成稱為紋理(texture)結構之微小的凹凸結構。紋理結構之形成，係使用鹼性溶液及添加劑。藉由表面的微小的凹凸結構，可使入射到基板之光在基板表面多重反射，減低光的反射損失。而且，由於光路長度增長，光吸收會增大。結果，就可預期會有短路電流之增大。另外，圖式中為了簡化而未顯示紋理結構。形成紋理結構後，進行例如RCA洗淨、SPM(Sulfuric Acid Hydrogen Peroxide Mixture)洗淨、HPM(Hydrochloric Acid Hydrogen Peroxide Mixture)洗淨，將附著於基板表面之因為有機物或金屬污染等而附著上的附著物去除掉。 First, an n-type single crystal germanium substrate 100 is prepared. The crystal ruthenium substrate is produced by cutting a silicon ingot by a mechanical cutting method such as a wire saw, and the surface is left with contamination or damage. ). Therefore, the damaged layer existing on the surface of the n-type single crystal germanium substrate 100 is removed by a wet etching procedure using an alkaline solution such as a sodium hydroxide solution. Then, a minute uneven structure called a texture structure is formed on the surface of the n-type single crystal germanium substrate 100. The formation of the texture structure uses an alkaline solution and an additive. The light incident on the substrate can be multi-reflected on the surface of the substrate by the minute uneven structure on the surface, thereby reducing the reflection loss of light. Moreover, as the optical path length increases, the light absorption increases. As a result, an increase in short-circuit current can be expected. In addition, the texture structure is not shown in the drawings for the sake of simplicity. After forming the texture structure, for example, RCA cleaning, SPM (Sulfuric Acid) The Hydrogen Peroxide Mixture is washed and HPM (Hydrochloric Acid Hydrogen Peroxide Mixture) is washed to remove adhering substances adhering to the surface of the substrate due to contamination by organic substances or metals.

接著，如第3圖(a)所示，在步驟S100，在n型單晶矽基板100的受光面100A上形成p型雜質擴散層103。在n型單晶矽基板100上以使用BBr3之氣相反應、或使用B2H6之大氣壓化學氣相沉積(Air Pressure Chemical Vapor Deposition：APCVD)法等之氣相法形成BSG膜後，在擴散爐中使硼熱擴散。亦可藉由離子植入將硼打入基板內，然後在擴散爐中使硼熱擴散。此時，所形成的p型雜質擴散層103的表面電阻(sheet resistance)較佳為在例如50以上未達150Ω/□。表面電阻係考慮在擴散層內之少數載子再結合、光吸收、與電極之接觸電阻而決定。 Next, as shown in FIG. 3(a), in step S100, a p-type impurity diffusion layer 103 is formed on the light-receiving surface 100A of the n-type single crystal germanium substrate 100. After the BSG film is formed on the n-type single crystal germanium substrate 100 by a gas phase reaction using BBr 3 or a gas phase method using an atmospheric pressure chemical vapor deposition (APCVD) method such as B 2 H 6 , The boron is thermally diffused in the diffusion furnace. Boron can also be driven into the substrate by ion implantation and then thermally diffused in the diffusion furnace. At this time, the sheet resistance of the formed p-type impurity diffusion layer 103 is preferably, for example, 50 or more and less than 150 Ω/□. The surface resistance is determined by considering the minority carrier recombination, light absorption, and contact resistance with the electrode in the diffusion layer.

在形成由BSG膜101所構成之p型雜質擴散源時若係採用APCVD法，則可只將BSG膜形成於n型單晶矽基板100的受光面100A。但是，因為基板端面及背面也會多少有些沉積，所以較佳為在BSG膜形成後以0.5%以上未達1.0%之程度的氫氟酸(hydrofluoric acid)將沉積到背面的部分去除掉。另外，在形成p型雜質擴散源後，較佳為形成NSG(Non doped Silicate Glass：無摻雜矽酸鹽玻璃)膜102來作為介電質膜。因為NSG膜102發揮罩蓋(cap)層之作用而防止由BSG膜101所構成之p型雜質擴散源中的硼脫離到氣相中，所以可有效率地使硼擴散。此外，NSG膜102也發揮在n型單晶矽基板100的背面100B形成n型 雜質擴散層之際之擴散阻障層之作用。作為p型雜質擴散源之BSG膜101的膜厚及NSG膜102的膜厚，分別在例如30nm以上未達150nm及100nm以上未達500nm。兩者的膜厚若太薄就無法發揮作為擴散源及罩蓋層或阻障層之作用，太厚則形成及去除都有困難，所以較佳為設定在上述範圍內。 When the p-type impurity diffusion source composed of the BSG film 101 is formed by the APCVD method, only the BSG film can be formed on the light-receiving surface 100A of the n-type single crystal germanium substrate 100. However, since the end surface and the back surface of the substrate are somewhat deposited, it is preferable to remove the portion deposited on the back surface with hydrofluoric acid at a level of 0.5% or more and less than 1.0% after the formation of the BSG film. Further, after forming a p-type impurity diffusion source, it is preferable to form an NSG (Non doped Silicate Glass) film 102 as a dielectric film. Since the NSG film 102 functions as a cap layer to prevent boron in the p-type impurity diffusion source composed of the BSG film 101 from being desorbed into the gas phase, boron can be efficiently diffused. Further, the NSG film 102 also functions to form an n-type on the back surface 100B of the n-type single crystal germanium substrate 100. The role of the diffusion barrier layer at the time of the impurity diffusion layer. The film thickness of the BSG film 101 and the film thickness of the NSG film 102 as the p-type impurity diffusion source are, for example, 30 nm or more and less than 150 nm and 100 nm or less and less than 500 nm. If the film thickness of both is too thin, it cannot function as a diffusion source and a cap layer or a barrier layer. If it is too thick, it is difficult to form and remove it, so it is preferably set within the above range.

在形成作為p型雜質擴散源之BSG膜101時若係採用BBr3氣相反應，則BSG膜不只會形成於受光面100A也會形成於背面100B側，所以在受光面100A的BSG膜上形成利用熱氧化膜或氮化膜而構成的阻障層之後，在利用氫氟酸將背面側的BSG膜去除掉之後，還要利用硝酸氫氟酸(fluonitric acid)或氫氧化鈉等的處理劑將整個背面的p型雜質擴散層103去除掉。其中，氮化膜可利用例如電漿CVD(plasma CVD)法(使用矽烷氣或氮氣或氨氣(ammonia gas)之電漿CVD法)來形成。因為此等阻障層在之後的磷擴散時也要發揮作為阻障層之作用，所以厚度較佳為形成在50nm以上。 When a BBr 3 gas phase reaction is formed in the BSG film 101 as a p-type impurity diffusion source, the BSG film is formed not only on the light-receiving surface 100A but also on the back surface 100B side, so that it is formed on the BSG film of the light-receiving surface 100A. After the barrier layer formed of the thermal oxide film or the nitride film is used, after the BSG film on the back side is removed by hydrofluoric acid, a treatment agent such as fluonitric acid or sodium hydroxide is used. The p-type impurity diffusion layer 103 on the entire back surface is removed. Among them, the nitride film can be formed by, for example, a plasma CVD method (a plasma CVD method using decane gas or nitrogen gas or ammonia gas). Since these barrier layers also function as a barrier layer in the subsequent diffusion of phosphorus, the thickness is preferably formed to be 50 nm or more.

接著，如第3圖(b)所示，在步驟S101，在n型單晶矽基板100的背面100B上形成低濃度n型雜質擴散層104。首先利用氫氟酸將n型單晶矽基板100的背面100B的自然氧化膜去除掉。然後以POCl3氣相反應、或使用PH3之APCVD等的氣相法在基板上形成PSG(磷矽酸鹽玻璃：Phosphorus Silicate Glass)膜105後，在擴散爐中使磷熱擴散。然後，利用氫氟酸將PSG膜105完全去除掉。 在以POCl3氣相反應來形成PSG膜105之情況，係將基板導入擴散爐內，然後一邊使氮氣流動一邊將溫度升高至擴散溫度。在為磷之情況，擴散溫度係在例如750℃以上未達900℃。到達擴散溫度就使POCl3起泡(bubbling)使之與氮氣、氧氣合流後導入爐內。然後維持溫度例如1至60分鐘的程度，以在形成PSG膜105的同時使磷擴散。結果，就形成低濃度n型雜質擴散層104。此處，較佳為使低濃度n型雜質擴散層104的表面電阻在100Ω/□以上400Ω/□以下。 Next, as shown in FIG. 3(b), in step S101, a low-concentration n-type impurity diffusion layer 104 is formed on the back surface 100B of the n-type single crystal germanium substrate 100. First, the natural oxide film of the back surface 100B of the n-type single crystal germanium substrate 100 is removed by hydrofluoric acid. Then, a PSG (Phosphorus Silicate Glass) film 105 is formed on the substrate by a gas phase reaction of POCl 3 or a vapor phase method using APCVD of PH 3 or the like, and then phosphorus is thermally diffused in a diffusion furnace. Then, the PSG film 105 was completely removed by hydrofluoric acid. In the case where the PSG film 105 is formed by a gas phase reaction of POCl 3 , the substrate is introduced into a diffusion furnace, and then the temperature is raised to the diffusion temperature while flowing nitrogen gas. In the case of phosphorus, the diffusion temperature is, for example, 750 ° C or higher and less than 900 ° C. When the diffusion temperature is reached, the POCl 3 is bubbling and combined with nitrogen and oxygen to be introduced into the furnace. The temperature is then maintained, for example, to the extent of 1 to 60 minutes to diffuse phosphorus while forming the PSG film 105. As a result, the low concentration n-type impurity diffusion layer 104 is formed. Here, it is preferable that the surface resistance of the low-concentration n-type impurity diffusion layer 104 is 100 Ω/□ or more and 400 Ω/□ or less.

接著，在步驟S102，在所形成的低濃度n型雜質擴散層104上的一部分形成高濃度n型雜質擴散源106且將之形成為梳形圖案(pattern)狀，然後使之乾燥。高濃度n型雜質擴散源106的形成方法，可採用網版(screen)印刷法、噴墨印刷法(ink jet print)等之成膜方法。擴散源之乾燥，係在例如輸送帶(conveyor)式回焊(reflow)爐中以200℃進行10分鐘。高濃度n型雜質擴散源106的圖案寬度因為最終會成為電極開口寬度，所以較佳為在20μm以上未達100μm。另外，高濃度n型雜質擴散源106的膜厚係在例如1μm以上未達20μm。高濃度n型雜質擴散源106的梳形圖案間的節距(pitch)係在例如0.3mm以上未達3.0mm。 Next, in step S102, a high-concentration n-type impurity diffusion source 106 is formed on a portion of the formed low-concentration n-type impurity diffusion layer 104 and formed into a comb pattern, and then dried. As a method of forming the high-concentration n-type impurity diffusion source 106, a film formation method such as a screen printing method or an ink jet printing method can be employed. The drying of the diffusion source is carried out at 200 ° C for 10 minutes in, for example, a conveyor type reflow furnace. Since the pattern width of the high-concentration n-type impurity diffusion source 106 eventually becomes the electrode opening width, it is preferably 20 μm or more and less than 100 μm. Further, the film thickness of the high-concentration n-type impurity diffusion source 106 is, for example, 1 μm or more and less than 20 μm. The pitch between the comb patterns of the high-concentration n-type impurity diffusion source 106 is, for example, 0.3 mm or more and less than 3.0 mm.

接著，如第3圖(c)所示，在步驟S103，在乾燥後將n型單晶矽基板100導入擴散爐，並一邊使氮氣流動一邊將溫度升高至900℃以上未達1100℃的溫度，然 後在氮氣及氧氣的混合氣體環境下保持一定時間，以在高濃度n型雜質擴散源106的正下方形成高濃度n型雜質擴散層107，同時在未形成有高濃度n型雜質擴散源106之區域形成熱氧化膜108。氧氣的流量係在例如氮氣及氧氣的混合氣體的總氣體流量的10%以上80%以下，且較佳為在10%以上未達40%。隨著氧氣流量之增加，在低濃度n型雜質擴散層104上形成熱氧化膜108的速度會增快。熱氧化膜108會吸收存在於低濃度n型雜質擴散層104的表面及表面附近之磷，使表面濃度降低，所以氧氣流量太大的話會減弱低濃度n型雜質擴散層104的電場效果。因此，氧氣的流量較佳為在全體的10%以上未達40%。熱處理時間係為例如1到60分鐘。此時，高濃度n型雜質擴散層107的表面電阻係考慮了與電極的接觸電阻等之電阻而設定在例如5Ω/□以上50Ω/□以下。實施形態1中雖然使用氮氣與氧氣的混合氣體，但亦可使用氧氣與氬氣等的惰性氣體之混合氣體，只要氧氣的含有量滿足上述值即可。 Next, as shown in FIG. 3(c), in step S103, after drying, the n-type single crystal germanium substrate 100 is introduced into a diffusion furnace, and the temperature is raised to 900 ° C or higher and less than 1100 ° C while flowing nitrogen gas. Temperature, then Thereafter, it is kept for a certain period of time in a mixed gas atmosphere of nitrogen and oxygen to form a high-concentration n-type impurity diffusion layer 107 directly under the high-concentration n-type impurity diffusion source 106, while a high-concentration n-type impurity diffusion source 106 is not formed. The region is formed with a thermal oxide film 108. The flow rate of oxygen is, for example, 10% or more and 80% or less of the total gas flow rate of the mixed gas of nitrogen gas and oxygen gas, and preferably 10% or more and less than 40%. As the oxygen flow rate increases, the speed at which the thermal oxide film 108 is formed on the low concentration n-type impurity diffusion layer 104 increases. The thermal oxide film 108 absorbs phosphorus present on the surface and the vicinity of the surface of the low-concentration n-type impurity diffusion layer 104 to lower the surface concentration. Therefore, if the oxygen flow rate is too large, the electric field effect of the low-concentration n-type impurity diffusion layer 104 is weakened. Therefore, the flow rate of oxygen is preferably less than 40% of the entire 10% or more. The heat treatment time is, for example, 1 to 60 minutes. In this case, the surface resistance of the high-concentration n-type impurity diffusion layer 107 is set to, for example, 5 Ω/□ or more and 50 Ω/□ or less in consideration of resistance such as contact resistance with an electrode. In the first embodiment, a mixed gas of nitrogen gas and oxygen gas is used, but a mixed gas of oxygen gas and an inert gas such as argon gas may be used as long as the oxygen content satisfies the above value.

另外，氧氣之供給可在升溫工序中開始，且可在擴散溫度到達以前停止供給。在擴散溫度到達後仍繼續供給氧氣，就會因為氧化膜在低濃度擴散層上形成、以及從擴散源擴散到氣相中之磷被氧化因而附著在基板表面之磷原子量減少等原因而可抑制磷從擴散源擴散到低濃度擴散層。但是，也有低濃度擴散層的表面磷濃度降得太低之虞。因此，可在途中停止氧之供給。可依據雜質擴散源的元素之擴散特性來調整氧的供給、停止的時點(timing) 而得到希望的擴散輪廓(profile)。 Further, the supply of oxygen can be started in the temperature rising process, and the supply can be stopped before the diffusion temperature is reached. When oxygen is continuously supplied after the diffusion temperature is reached, it is suppressed because the oxide film is formed on the low concentration diffusion layer, and the phosphorus diffused from the diffusion source into the gas phase is oxidized, thereby reducing the amount of phosphorus atoms adhering to the surface of the substrate. Phosphorus diffuses from the diffusion source to the low concentration diffusion layer. However, there is also a tendency that the surface phosphorus concentration of the low concentration diffusion layer is lowered too low. Therefore, the supply of oxygen can be stopped on the way. The timing of supply and stop of oxygen can be adjusted according to the diffusion characteristics of the elements of the impurity diffusion source. And get the desired diffusion profile.

然後，如第4圖(a)所示，在步驟S104，在熱氧化膜108及高濃度n型雜質擴散源106之上形成背面側介電質層109。背面側介電質層109係發揮作為低濃度n型雜質擴散層104的鈍化膜之作用，其材料為例如氮化矽、氮氧化矽、氧化鋁(aluminum oxide)、非晶矽、微晶矽等之介電質層。背面側介電質層109亦可為複數個膜的積層結構。可採用例如電漿CVD法來形成氮化矽膜。氮化矽膜係發揮作為抗反射膜之作用，而且在形成氮化矽膜之際注入的氫會存在於n型單晶矽基板100與氧化矽膜的界面之未結合破面等的缺陷，使鈍化效果提高。因此，少數載子之再結合會受到抑制，太陽電池特性會提高。 Then, as shown in FIG. 4(a), in step S104, the back side dielectric layer 109 is formed on the thermal oxide film 108 and the high concentration n-type impurity diffusion source 106. The back side dielectric layer 109 functions as a passivation film of the low concentration n-type impurity diffusion layer 104, and is made of, for example, tantalum nitride, hafnium oxynitride, aluminum oxide, amorphous germanium, or microcrystalline germanium. Wait for the dielectric layer. The back side dielectric layer 109 may also be a laminated structure of a plurality of films. A tantalum nitride film can be formed by, for example, a plasma CVD method. The tantalum nitride film functions as an antireflection film, and hydrogen injected during the formation of the tantalum nitride film may be present in the unbonded surface of the n-type single crystal germanium substrate 100 and the tantalum oxide film. Improve the passivation effect. Therefore, the recombination of a few carriers will be suppressed, and the characteristics of the solar cell will increase.

又，因為背面側介電質層109係在雜質從高濃度n型雜質擴散源106擴散後形成，所以背面側介電質層109的材料也可從非晶矽膜、微晶矽膜等之熱耐性在900℃以下的材料中選擇。因此，可將背面側介電質層109的材料選擇成能讓鈍化效果達到最大限度之材料，所以對於太陽電池特性之提高很有利。 Further, since the back side dielectric layer 109 is formed by diffusing impurities from the high concentration n-type impurity diffusion source 106, the material of the back side dielectric layer 109 may be from an amorphous germanium film or a microcrystalline germanium film. The heat resistance is selected from materials below 900 °C. Therefore, the material of the back side dielectric layer 109 can be selected as a material which can maximize the passivation effect, and is therefore advantageous for the improvement of solar cell characteristics.

接著，如第4圖(b)所示，在步驟S105，以使用氫氟酸之濕式蝕刻來去除高濃度n型雜質擴散源106及位於其上之背面側介電質層109b，藉由掀離形成開口。高濃度n型雜質擴散源106與背面側介電質層109a相比具有10至50倍左右之厚度，所以即使位於背面側介電質層109b之下，也可輕易地與氫氟酸接觸。選擇蝕刻率(etching rate)比n型雜質擴散源106低之材料，例如氮化矽膜來作為背面側介電質層109，就容易將高濃度n型雜質擴散源106去除。同時，使得位於高濃度n型雜質擴散源106之上之背面側介電質層109b也掀離，而形成開口h。此時，背面側介電質層109的厚度，係設定為將高濃度n型雜質擴散源106去除後仍殘存有可維持鈍化效果的膜厚以上之厚度。例如，在氧化矽膜與氮化矽膜的積層結構之情況，係設定為氫氟酸處理後的總膜厚會為70至90nm左右之厚度。另外，此時也利用氫氟酸而同時將堆積於受光面上之作為p型雜質擴散源之BSG膜101及NSG膜102也去除掉。 Next, as shown in FIG. 4(b), in step S105, the high-concentration n-type impurity diffusion source 106 and the back-side dielectric layer 109b located thereon are removed by wet etching using hydrofluoric acid. The opening forms an opening. Since the high-concentration n-type impurity diffusion source 106 has a thickness of about 10 to 50 times as compared with the back-side dielectric layer 109a, it can be easily brought into contact with hydrofluoric acid even under the back-side dielectric layer 109b. Select etch rate (etching The material having a lower density than the n-type impurity diffusion source 106, for example, a tantalum nitride film as the back side dielectric layer 109, is likely to remove the high concentration n-type impurity diffusion source 106. At the same time, the back side dielectric layer 109b located on the high concentration n-type impurity diffusion source 106 is also separated to form the opening h. At this time, the thickness of the back side dielectric layer 109 is set such that the thickness of the film thickness or more which can maintain the passivation effect remains after the high concentration n-type impurity diffusion source 106 is removed. For example, in the case of a laminated structure of a ruthenium oxide film and a tantalum nitride film, the total film thickness after the hydrofluoric acid treatment is set to be about 70 to 90 nm. Further, at this time, the BSG film 101 and the NSG film 102 which are the p-type impurity diffusion sources deposited on the light-receiving surface are also removed by hydrofluoric acid.

接著，如第4圖(c)所示，在步驟S106，在受光面100A的p型雜質擴散層103之上形成受光面側介電質層110及抗反射膜111。受光面側介電質層110可採用以例如原子層沉積法(Atomic Layer Deposition：ALD)或CVD法形成之氧化鋁膜等之介電質層。已知特別是氧化鋁膜具有負的固定電荷，對於p型雜質擴散層會發揮很好的鈍化效果。氧化鋁膜的膜厚係在例如2nm以上未達50nm。 Next, as shown in FIG. 4(c), in step S106, the light-receiving surface-side dielectric layer 110 and the anti-reflection film 111 are formed on the p-type impurity diffusion layer 103 of the light-receiving surface 100A. The light-receiving side dielectric layer 110 may be a dielectric layer such as an aluminum oxide film formed by, for example, Atomic Layer Deposition (ALD) or CVD. It is known that, in particular, the aluminum oxide film has a negative fixed charge, and a good passivation effect is exerted for the p-type impurity diffusion layer. The film thickness of the aluminum oxide film is, for example, 2 nm or more and less than 50 nm.

在受光面側介電質層110之上形成抗反射膜111。抗反射膜111係採用以例如電漿CVD法形成之氮化矽膜。抗反射膜111的厚度係依據氧化鋁膜的厚度而設計在對於太陽光光譜(spectrum)最合適的膜厚，例如30nm以上未達80nm之程度。 An anti-reflection film 111 is formed on the light-receiving side dielectric layer 110. The anti-reflection film 111 is a tantalum nitride film formed by, for example, a plasma CVD method. The thickness of the anti-reflection film 111 is designed to be the most suitable film thickness for the solar spectrum depending on the thickness of the aluminum oxide film, for example, 30 nm or more and less than 80 nm.

最後，進行步驟S107，在n型單晶矽基板100的受光面100A及背面100B形成正電極112及負電極 113，而完成第1圖(a)及(b)所示之太陽電池。受光面100A側之正電極112係以網版印刷法等之塗佈法將含有金屬粒子及玻璃粒子之糊(paste)塗佈成梳形圖案狀，然後使之乾燥而形成。背面100B側之負電極113係在開口h塗佈含銀之糊(paste)再使之乾燥而形成。糊之乾燥係在例如乾燥爐(oven)中以200℃之溫度進行10分鐘左右。乾燥後，以800℃左右之高溫同時對正電極112及負電極113進行熱處理，將之燒製成形。此時，因為正電極112之糊含有玻璃粒子，所以在燒製之下金屬會貫通受光面側介電質層110及抗反射膜111，而與p型雜質擴散層103電性接觸。另一方面，因為負電極113之糊不含有玻璃粒子，所以即使受到高溫的燒製，金屬也不會貫通介電質層。因此，即使在背面側介電質層109a上形成背面100B的電極糊，該部分也不會有特性降低之虞。因此，可將背面100B的電極糊塗佈在比開口h寬之範圍，亦可塗佈在背面100B的全面，因此可不用對位地在高濃度n型雜質擴散層107上形成負電極113。若考慮糊的使用量，可形成為從開口h左右超出最大100μm左右，且較佳為左右超出10μm左右。可根據印刷機的精度而使超出的程度適度地變化。以下，說明以往的電極對位方法，並針對本實施形態的效果進行與以往的方法之比較。 Finally, in step S107, the positive electrode 112 and the negative electrode are formed on the light receiving surface 100A and the back surface 100B of the n-type single crystal germanium substrate 100. 113, and complete the solar cells shown in Figures 1 (a) and (b). The positive electrode 112 on the light-receiving surface 100A side is formed by applying a paste containing metal particles and glass particles in a comb-like pattern by a coating method such as a screen printing method, and then drying it. The negative electrode 113 on the back surface 100B side is formed by applying a paste containing silver to the opening h and drying it. The drying of the paste is carried out, for example, in a drying oven at a temperature of 200 ° C for about 10 minutes. After drying, the positive electrode 112 and the negative electrode 113 are simultaneously heat-treated at a high temperature of about 800 ° C, and fired into a shape. At this time, since the paste of the positive electrode 112 contains glass particles, the metal penetrates the light-receiving surface-side dielectric layer 110 and the anti-reflection film 111 to be electrically contacted with the p-type impurity diffusion layer 103. On the other hand, since the paste of the negative electrode 113 does not contain glass particles, the metal does not penetrate the dielectric layer even if it is fired at a high temperature. Therefore, even if the electrode paste of the back surface 100B is formed on the back side dielectric layer 109a, there is no deterioration in characteristics of this portion. Therefore, the electrode paste of the back surface 100B can be applied in a range wider than the opening h, or can be applied to the entire surface of the back surface 100B, so that the negative electrode 113 can be formed on the high-concentration n-type impurity diffusion layer 107 without alignment. When the amount of use of the paste is considered, it may be formed so as to exceed a maximum of about 100 μm from the opening h, and preferably about 10 μm from the left and right. The degree of excess can be varied moderately depending on the accuracy of the printing press. Hereinafter, a conventional electrode alignment method will be described, and the effects of the present embodiment will be compared with the conventional methods.

以往之背面電極的形成，係利用印刷機的對準(alignment)機能將電極遮罩(mask)的圖案對準在高濃度n型雜質擴散層的圖案上，然後從介電質層之上塗佈糊 及使糊乾燥，再利用高溫燒製使之貫通介電質層，以此方式使電極與高濃度n型雜質擴散層連接。然而，首先若高濃度n型雜質擴散層的辨識性很差，電極圖案就不會與高濃度n型雜質擴散層的圖案一致，而會有產生位置偏差之情形。再者，就算可利用印刷機的對準機能而正確地對位，也會因為糊的特性或印刷遮罩的伸展變形等原因而有電極圖案從高濃度n型雜質擴散層的圖案偏離或超出之可能性。另外，若為了防止如此之偏離而將高濃度n型雜質擴散層形成得比電極左右各寬5μm至50μm左右的話，則會有高濃度n型雜質擴散層與介電質層間的載子再結合會增加，造成特性降低之問題。 In the past, the formation of the back electrode was performed by aligning the pattern of the electrode mask on the pattern of the high-concentration n-type impurity diffusion layer by the alignment function of the printer, and then coating it from the dielectric layer. Cloth paste And the paste is dried, and then fired at a high temperature to penetrate the dielectric layer, thereby connecting the electrode to the high concentration n-type impurity diffusion layer. However, first, if the visibility of the high-concentration n-type impurity diffusion layer is poor, the electrode pattern does not coincide with the pattern of the high-concentration n-type impurity diffusion layer, and there is a case where positional deviation occurs. Furthermore, even if the alignment function of the printing press can be correctly aligned, the pattern of the electrode pattern deviates from or exceeds the pattern of the high-concentration n-type impurity diffusion layer due to the characteristics of the paste or the stretching deformation of the printing mask. The possibility. In addition, if the high-concentration n-type impurity diffusion layer is formed to be about 5 μm to 50 μm wider than the left and right sides of the electrode in order to prevent such a deviation, the carrier of the high-concentration n-type impurity diffusion layer and the dielectric layer is recombined. Will increase, causing problems with reduced features.

另一方面，本實施形態係藉由將糊塗佈在比開口h寬的範圍，而可不用進行對位地將負電極113形成在高濃度n型雜質擴散層107之上。而且，即使將負電極113形成得比開口h寬，負電極113也不是會貫通背面側介電質層109a之形狀，所以在超出開口h的電極下發生再結合的情形不會增加，開路電壓降低之顧慮很小。以及，因為從基板的厚度方向看，高濃度n型雜質擴散層107與開口h為相同位置、形狀、及大小，所以與將高濃度n型雜質擴散層形成得比負電極寬之以往的方法相比較，可抑制高濃度n型雜質擴散層107之從基板的背面方向看時的面積。因而，開路電壓會提高。 On the other hand, in the present embodiment, by applying the paste to a range wider than the opening h, the negative electrode 113 can be formed on the high-concentration n-type impurity diffusion layer 107 without alignment. Further, even if the negative electrode 113 is formed wider than the opening h, the negative electrode 113 does not penetrate the shape of the back side dielectric layer 109a, so that recombination occurs under the electrode beyond the opening h, and the open circuit voltage is not increased. The concerns of lowering are small. Further, since the high-concentration n-type impurity diffusion layer 107 and the opening h have the same position, shape, and size as viewed in the thickness direction of the substrate, the conventional method of forming the high-concentration n-type impurity diffusion layer to be wider than the negative electrode is used. In comparison, the area of the high-concentration n-type impurity diffusion layer 107 when viewed from the back surface direction of the substrate can be suppressed. Therefore, the open circuit voltage will increase.

又，就以往的方法而言，會有在形成高濃度n型雜質擴散層之工序、及使電極對準於其上之工序這 兩個工序中發生偏差之可能性，偏差相疊加就會產生更大的偏差。相對的，根據本實施形態的自對準程序，即使在高濃度n型雜質擴散層之形成時發生偏差，也因為會與實際形成的圖案一致地進行開口及電極之形成，而不會發生偏差相疊加之情形，可得到穩定的對位精度及特性。 Moreover, in the conventional method, there are a step of forming a high concentration n-type impurity diffusion layer and a step of aligning the electrodes thereon. The possibility of deviation in the two processes, the superposition of the deviations will produce a larger deviation. On the other hand, according to the self-alignment program of the present embodiment, even when the high-concentration n-type impurity diffusion layer is formed, variations occur, and the openings and the electrodes are formed in conformity with the actually formed pattern without deviation. In the case of superposition, stable alignment accuracy and characteristics can be obtained.

而且，在負電極113方面，可採用低溫燒製銀糊。因為在掀離工序中會將接觸區域的介電質層去除，所以無需在負電極113的燒製工序中使之貫通介電質層。因此，可用低溫進行燒製，可維持背面側介電質層109的鈍化性能。在此情況，係先印刷及燒製完成正電極112之後，才進行負電極113之印刷及乾燥而形成電極。具體而言，係在形成開口h後，在受光面100A印刷含有金屬粒子及玻璃粒子之糊及使之乾燥。接著以800℃左右之高溫燒製受光面100A的糊，使p型雜質擴散層103與正電極112相接觸。在正電極112形成後，在高濃度n型雜質擴散層107的露出部印刷上要低溫燒製的銀，然後以200℃左右之低溫使之乾燥而形成負電極113。 Moreover, in terms of the negative electrode 113, a low temperature firing silver paste can be employed. Since the dielectric layer in the contact region is removed in the detachment step, it is not necessary to penetrate the dielectric layer in the firing step of the negative electrode 113. Therefore, firing can be performed at a low temperature to maintain the passivation performance of the back side dielectric layer 109. In this case, after the positive electrode 112 is printed and fired, the negative electrode 113 is printed and dried to form an electrode. Specifically, after the opening h is formed, the paste containing the metal particles and the glass particles is printed on the light-receiving surface 100A and dried. Next, the paste of the light-receiving surface 100A is fired at a high temperature of about 800 ° C, and the p-type impurity diffusion layer 103 is brought into contact with the positive electrode 112. After the positive electrode 112 is formed, silver which is to be fired at a low temperature is printed on the exposed portion of the high-concentration n-type impurity diffusion layer 107, and then dried at a low temperature of about 200 ° C to form a negative electrode 113.

如以上所述之實施形態1，係自對準地將電極形成在高濃度雜質擴散層(第一雜質擴散層)上，且將擴散中形成的熱氧化膜、與擴散後形成的介電質膜之積層結構體用作為鈍化膜，所以會產生可得到能使鈍化效果發揮到最大限度，轉換效率高之太陽電池之製造方法這樣的效果。熱氧化膜亦可在擴散之前形成。 According to the first embodiment described above, the electrode is formed on the high-concentration impurity diffusion layer (first impurity diffusion layer) in a self-aligned manner, and the thermal oxide film formed during the diffusion and the dielectric formed after the diffusion are formed. Since the laminated structure of the film is used as a passivation film, there is an effect that a solar cell manufacturing method capable of maximizing the passivation effect and high conversion efficiency can be obtained. The thermal oxide film can also be formed prior to diffusion.

實施形態2. Embodiment 2.

以下，參照圖式來說明實施形態2。第5圖係顯示以本發明的實施形態2之太陽電池之製造方法形成的太陽電池之剖面圖，其上視圖係與第1圖(a)一樣。第6圖係顯示實施形態2之太陽電池之製造方法之流程圖，第7圖(a)及(b)係顯示實施形態2之太陽電池之製造方法之各工序剖面圖。第8圖係顯示在步驟S103中之擴散爐的溫度輪廓(profile)。製程的大部分與實施形態1一樣，不同之點在於：不形成低濃度n型雜質擴散層104，但在n型單晶矽基板100的背面正上方形成作為介電質層之熱氧化膜108。 Hereinafter, the second embodiment will be described with reference to the drawings. Fig. 5 is a cross-sectional view showing a solar cell formed by the method for manufacturing a solar cell according to the second embodiment of the present invention, and the top view is the same as Fig. 1(a). Fig. 6 is a flow chart showing a method of manufacturing a solar cell according to a second embodiment, and Fig. 7 (a) and (b) are cross-sectional views showing respective steps of a method for producing a solar cell according to a second embodiment. Fig. 8 is a view showing the temperature profile of the diffusion furnace in step S103. The majority of the process is the same as that of the first embodiment, except that the low-concentration n-type impurity diffusion layer 104 is not formed, but the thermal oxide film 108 as a dielectric layer is formed directly over the back surface of the n-type single crystal germanium substrate 100. .

本實施形態係在已於受光面100A形成p型雜質擴散層103之後，並不實施形成低濃度n型雜質擴散層之步驟S101，而是如第7圖(a)所示，在步驟S102於背面100B形成高濃度n型雜質擴散源106。 In the present embodiment, after the p-type impurity diffusion layer 103 is formed on the light-receiving surface 100A, the step S101 of forming the low-concentration n-type impurity diffusion layer is not performed, but as shown in FIG. 7(a), in step S102. The back surface 100B forms a high concentration n-type impurity diffusion source 106.

然後，如第7圖(b)所示，在步驟S102將基板導入擴散爐內，並使氧氣流動而形成氧化膜之後，才使雜質從高濃度n型雜質擴散源106擴散。擴散時間為例如1到60分鐘。此時的氧氣流量較佳為在全部氣體流量的80%以上未達100%。實施形態2中也一樣採用由例如氮氣及氧氣所構成之混合氣體。 Then, as shown in Fig. 7(b), after the substrate is introduced into the diffusion furnace in step S102, and oxygen gas flows to form an oxide film, the impurities are diffused from the high-concentration n-type impurity diffusion source 106. The diffusion time is, for example, 1 to 60 minutes. The oxygen flow rate at this time is preferably less than 100% of the total gas flow rate of 80% or more. In the second embodiment, a mixed gas composed of, for example, nitrogen gas and oxygen gas is used in the same manner.

在本實施形態的擴散工序中，係使時間圖(time chart)如第8圖中的實線a所示一邊切換溫度及環境氣體一邊進行升溫、加熱、及降溫。首先，將背面100B側已形成作為高濃度的第一雜質擴散源之由含有磷的摻雜 劑糊所構成的高濃度n型雜質擴散源106之n型單晶矽基板100送入已預熱至待機溫度T0之熱處理爐內，然後一邊供給氮氣一邊升溫至氧化溫度T1。使背面100B側形成熱氧化膜108的成膜環境，係在作為第一溫度之氧化溫度T1將供給氮氣切換為供給氧氣並維持一段預定的時間t0，將爐內氣體全換為氧氣而實施作為第一工序之氧化工序。實施形態2中雖然將氧化溫度T1設定為800℃，但氧化溫度T1可採用700℃到1100℃之溫度帶內的溫度，時間t0係為1到20分左右。較佳為將氧化溫度T1設定在700℃到850℃。若此氧化溫度T1未達700℃，氧化速度會太慢，超過850℃，則會在背面還未有充分的氧化膜被覆之前就已開始發生擴散，而無法避免有附著物在背面形成。以一定的溫度實施該氧化溫度T1，可穩定且確實地形成覆蓋背面100B之熱氧化膜108。 In the diffusion step of the present embodiment, the time chart is heated, heated, and cooled while switching the temperature and the ambient gas as indicated by the solid line a in FIG. First, the n-type single crystal germanium substrate 100 of the high-concentration n-type impurity diffusion source 106 composed of a phosphorus-containing dopant paste which has formed a high-concentration first impurity diffusion source on the back surface 100B side is supplied to the preheated The temperature is raised to the oxidation temperature T 1 while supplying nitrogen gas to the heat treatment furnace at the standby temperature T 0 . The film forming environment in which the thermal oxide film 108 is formed on the back surface 100B side is switched to supply oxygen gas at the oxidation temperature T 1 as the first temperature for a predetermined time t 0 , and the gas in the furnace is completely replaced by oxygen. The oxidation step as the first step is carried out. In the second embodiment, the oxidation temperature T 1 is set to 800 ° C, but the oxidation temperature T 1 may be a temperature in the temperature band of 700 ° C to 1100 ° C, and the time t 0 is about 1 to 20 minutes. It is preferred to set the oxidation temperature T 1 at 700 ° C to 850 ° C. If the oxidation temperature T 1 is less than 700 ° C, the oxidation rate will be too slow. When the temperature exceeds 850 ° C, diffusion will begin to occur before the back surface of the oxide film is sufficiently covered, and the formation of deposits on the back side cannot be avoided. By performing the oxidation temperature T 1 at a constant temperature, the thermal oxide film 108 covering the back surface 100B can be stably and surely formed.

送入熱處理爐內之n型單晶矽基板100其表面會因為爐內中含有的氧氣而氧化。該氧化因為受光面100A側已由作為p型雜質擴散源之BSG膜101及NSG膜覆蓋著，所以係選擇性地在沒有膜覆蓋著的背面100B側進行。本實施形態2係包含：在熱處理爐內，在雜質尚未從高濃度n型擴散源擴散之前將氧氣供給至熱處理爐內，以形成用來防止雜質橫方向擴散到背面100B之不希望有的情形之熱氧化膜108之工序。因此，與實施形態1相比，工序時間雖會增加，但除了抑制雜質從n型雜質擴散源往不希望有的方向擴散之效果之外，還可選擇希望的熱氧化 膜108的形成溫度或膜厚。 The surface of the n-type single crystal germanium substrate 100 fed into the heat treatment furnace is oxidized by the oxygen contained in the furnace. Since this oxidation is covered by the BSG film 101 and the NSG film which are the p-type impurity diffusion sources on the light-receiving surface 100A side, it is selectively performed on the side of the back surface 100B which is not covered with the film. In the second embodiment, oxygen is supplied into the heat treatment furnace before the impurities are diffused from the high-concentration n-type diffusion source in the heat treatment furnace to form an undesired situation for preventing the impurities from diffusing in the lateral direction to the back surface 100B. The process of thermally oxidizing the film 108. Therefore, although the process time is increased as compared with the first embodiment, in addition to the effect of suppressing the diffusion of impurities from the n-type impurity diffusion source into an undesired direction, the desired thermal oxidation can be selected. The formation temperature or film thickness of the film 108.

另外，氧化工序雖然係將溫度都維持在第一溫度T1，但亦可在氧氣供給開始後升溫到作為擴散溫度的第二溫度T2之升溫工序中實施。此變形例的時間圖係如第8圖中的虛線b所示。此情況雖可縮短工序，但因為在爐內完全置換為氧氣之前就開始升溫，所以容易發生基板間或基板面內的氧化膜厚或磷濃度不均之情形。 Further, although the oxidation step is performed at the first temperature T 1 while maintaining the temperature, it may be carried out in a temperature rising step of raising the temperature to the second temperature T 2 as the diffusion temperature after the start of the oxygen supply. The time chart of this modification is as shown by the broken line b in Fig. 8. In this case, the process can be shortened. However, since the temperature rises before the furnace is completely replaced with oxygen, the oxide film thickness or the phosphorus concentration unevenness between the substrates or the substrate surface tends to occur.

接著在升溫至作為擴散溫度的第二溫度T2後，在含有例如氮氣、氬氣等的惰性氣體的爐內環境中加熱並維持一定的時間t1，而實施作為第二工序之擴散工序。本實施形態中，雖然將擴散溫度T2設定為950℃，但擴散溫度T2可採用800℃到1100℃之溫度帶內的溫度，時間t1係為1到60分鐘左右。 Next, after raising the temperature to the second temperature T 2 which is the diffusion temperature, it is heated and maintained for a predetermined time t 1 in an atmosphere containing an inert gas such as nitrogen or argon, and the diffusion step as the second step is carried out. In the present embodiment, the diffusion temperature T 2 is set to 950 ° C, but the diffusion temperature T 2 may be a temperature within a temperature band of 800 ° C to 1100 ° C, and the time t 1 is about 1 to 60 minutes.

如前述，在選擇性地在背面100B形成熱氧化膜108之後，使溫度到達會使雜質開始從高濃度n型雜質擴散源106擴散之溫度，例如900℃到1100℃的溫度，來形成希望的高濃度n型雜質擴散層107。此時的第二溫度T2係依據雜質的種類而決定。 As described above, after the thermal oxide film 108 is selectively formed on the back surface 100B, the temperature is reached at a temperature at which the impurity starts to diffuse from the high-concentration n-type impurity diffusion source 106, for example, a temperature of 900 ° C to 1100 ° C to form a desired one. A high concentration n-type impurity diffusion layer 107. The second temperature T 2 at this time is determined depending on the type of the impurity.

然後在雜質擴散結束後，在第三工序停止氧氣的供給，再在氮氣環境下開始降溫。 Then, after the diffusion of the impurities is completed, the supply of oxygen is stopped in the third step, and then the temperature is lowered in a nitrogen atmosphere.

藉由上述製程，可不使雜質擴散到n型雜質擴散源106所在的部分以外的部分之情況下，形成作為鈍化膜之熱氧化膜108。此結構係稱為PERL(Passivated Emitter and Rear Locally diffused，射極鈍化及背面局部擴 散)之結構，在鈍化膜的鈍化效果高之情況，雜質不會擴散到負電極113的正下方之高濃度n型雜質擴散層107以外這點，會防止在擴散層內之少數載子的再結合，所以在開路電壓的提高上很有效。而且，因為不會在n型雜質擴散源106以外的部分形成擴散層，所以雜質不易跑到n型單晶矽基板100的端面或受光面100A，不易發生p型雜質擴散層之反轉。因此，可使洩漏電流(leak current)減小，所以可靠性會提高。 According to the above process, the thermal oxide film 108 as a passivation film can be formed without diffusing impurities to a portion other than the portion where the n-type impurity diffusion source 106 is located. This structure is called PERL (Passivated Emitter and Rear Locally diffused), emitter passivation and back partial expansion In the case where the passivation effect of the passivation film is high, impurities do not diffuse beyond the high-concentration n-type impurity diffusion layer 107 directly under the negative electrode 113, and a minority carrier in the diffusion layer is prevented. Combined, it is effective in improving the open circuit voltage. Further, since the diffusion layer is not formed in a portion other than the n-type impurity diffusion source 106, the impurity does not easily reach the end surface of the n-type single crystal germanium substrate 100 or the light-receiving surface 100A, and the inversion of the p-type impurity diffusion layer is less likely to occur. Therefore, the leakage current can be reduced, so the reliability is improved.

然後，與實施形態1一樣，最後在n型單晶矽基板100的表面100A及背面100B形成正電極112及負電極113，完成第5圖所示之太陽電池。 Then, in the same manner as in the first embodiment, the positive electrode 112 and the negative electrode 113 are formed on the front surface 100A and the back surface 100B of the n-type single crystal germanium substrate 100, and the solar cell shown in Fig. 5 is completed.

本實施形態係藉由特別是熱氧化膜108之存在而抑制橫方向之擴散，使作為第一雜質擴散層之高濃度n型雜質擴散層107從n型單晶矽基板100的背面100B的一部分向受光面100A方向伸展。另外，負電極113係在開口h內與高濃度n型雜質擴散層107接觸，而且突出於覆蓋在背面100B之背面側介電質層109a(氮化矽膜)的一部分上。 In the present embodiment, the diffusion in the lateral direction is suppressed by the presence of the thermal oxide film 108 in particular, and the high-concentration n-type impurity diffusion layer 107 as the first impurity diffusion layer is partially formed from the back surface 100B of the n-type single crystal germanium substrate 100. It extends in the direction of the light receiving surface 100A. Further, the negative electrode 113 is in contact with the high-concentration n-type impurity diffusion layer 107 in the opening h, and protrudes over a portion of the back surface-side dielectric layer 109a (tantalum nitride film) covering the back surface 100B.

實施形態3. Embodiment 3.

以下，參照圖式來說明實施形態3。第9圖係顯示本發明的實施形態3之太陽電池之製造方法之流程圖。本實施形態與實施形態1大部分相同，不同之處只在於：不採用n型雜質擴散源之掀離步驟S105，而採用n型雜質擴散 源雷射開口步驟S105S，利用雷射照射將n型雜質擴散源的一部分或全面去除之點，所以省略製程的詳細說明。 Hereinafter, the third embodiment will be described with reference to the drawings. Fig. 9 is a flow chart showing a method of manufacturing a solar cell according to a third embodiment of the present invention. This embodiment is mostly the same as that of the first embodiment except that the n-type impurity diffusion is performed without using the n-type impurity diffusion source. The source laser opening step S105S uses laser irradiation to remove a part or all of the n-type impurity diffusion source, so that the detailed description of the process will be omitted.

實施形態3的特徵在於：不是利用濕式蝕刻而是利用雷射照射將n型雜質擴散源106及位於其上的背面側介電質層109b的一部分或全面去除。n型雜質擴散源雷射開口步驟S105S，係在形成背面側介電質層109之後對於n型雜質擴散源106照射雷射。此時，係選擇相對於n型雜質擴散源106(亦即含有磷之摻雜劑糊)會選擇性地產生能量吸收之波長的雷射。藉此，選擇性地去除n型雜質擴散源106，將位於其上的背面側介電質層109b也去除掉，使高濃度n型雜質擴散層107露出。與實施形態1一樣，在有高濃度n型雜質擴散層107露出之開口部進行電極印刷。印刷糊係形成為從開口部左右超出最大100μm左右，且較佳為左右超出10μm左右。 The third embodiment is characterized in that a part or all of the n-type impurity diffusion source 106 and the back side dielectric layer 109b located thereon are not completely removed by laser irradiation by wet etching. The n-type impurity diffusion source laser opening step S105S irradiates the n-type impurity diffusion source 106 with a laser after forming the back side dielectric layer 109. At this time, a laser which selectively generates a wavelength of energy absorption with respect to the n-type impurity diffusion source 106 (that is, a dopant paste containing phosphorus) is selected. Thereby, the n-type impurity diffusion source 106 is selectively removed, and the back side dielectric layer 109b located thereon is also removed, and the high concentration n-type impurity diffusion layer 107 is exposed. In the same manner as in the first embodiment, electrode printing is performed on the opening portion where the high-concentration n-type impurity diffusion layer 107 is exposed. The printing paste is formed to extend from the left and right sides by a maximum of about 100 μm, and preferably to the left and right by about 10 μm.

雷射可採用例如YAG雷射、YVO4雷射、CO2雷射。而且，可藉由調整雷射的種類、能量密度、脈衝振盪頻率、照射時間而在不對於n形單晶矽基板100造成損傷的情況下形成開口。在濕式蝕刻的情況，要使用對於氫氟酸等之蝕刻劑(etching)的耐性高之材料來作為背面側介電質層109，在雷射照射之情況，則可採用耐性低之材料，例如氧化矽膜或氧化鋁膜且單膜即可。 The laser can be, for example, a YAG laser, a YVO 4 laser, or a CO 2 laser. Further, the opening can be formed without causing damage to the n-type single crystal germanium substrate 100 by adjusting the type of the laser, the energy density, the pulse oscillation frequency, and the irradiation time. In the case of wet etching, a material having high resistance to etching of hydrofluoric acid or the like is used as the back side dielectric layer 109, and in the case of laser irradiation, a material having low resistance can be used. For example, a ruthenium oxide film or an aluminum oxide film may be used as a single film.

利用此方法，可防止因為濕式蝕刻而使其他的層劣化之情形，而更提高可靠性。實施形態3雖然是利用相對於高濃度n型雜質擴散源106會選擇性產生能量 吸收之波長的雷射來去除高濃度n型雜質擴散源106同時去除其上層的背面側介電質層109b，但在本說明書中將此亦視為廣義的掀離工序。 With this method, it is possible to prevent deterioration of other layers due to wet etching, and to improve reliability. In the third embodiment, the energy is selectively generated with respect to the high-concentration n-type impurity diffusion source 106. The laser of the absorbed wavelength removes the high-concentration n-type impurity diffusion source 106 while removing the upper-side back-side dielectric layer 109b, but this is also regarded as a generalized separation step in the present specification.

實施形態4. Embodiment 4.

以下，參照圖式來說明實施形態4。第10圖係顯示以本發明的實施形態4之太陽電池之製造方法形成的太陽電池之圖，其中(a)為上視圖，(b)為(a)的B-B剖面圖。第11圖係顯示實施形態4之太陽電池之製造方法之流程圖，第12圖(a)至(c)及第13圖(a)至(c)係顯示實施形態4之太陽電池之製造方法之各工序剖面圖。 Hereinafter, the fourth embodiment will be described with reference to the drawings. Fig. 10 is a view showing a solar cell formed by the method for producing a solar cell according to Embodiment 4 of the present invention, wherein (a) is a top view and (b) is a B-B cross-sectional view of (a). 11 is a flow chart showing a method of manufacturing a solar cell according to a fourth embodiment, and FIGS. 12(a) to (c) and 13 (a) to (c) are views showing a method of manufacturing a solar cell according to a fourth embodiment. A cross-sectional view of each process.

實施形態4係採用p型單晶矽基板200來替代n型單晶矽基板100之製程。因此，除了導電型與實施形態1相反之點以外，幾乎都相同，所以省略詳細的說明。實施形態4之太陽電池之製造方法係如第12圖(a)所示，在p型單晶矽基板200的受光面200A側形成作為第二導電型半導體層之n型雜質擴散層203。然後如第12圖(b)所示，在p型單晶矽基板200的背面200B上形成用來形成低濃度p型雜質擴散層204之p型雜質擴散源205。然後，將高濃度p型雜質擴散源206形成為梳形圖案狀並使之乾燥，然後送入擴散爐。然後，如第12圖(c)所示，在氮氣與氧氣之混合氣體環境下使雜質從高濃度p型雜質擴散源206擴散來形成高濃度p型雜質擴散層207及熱氧化膜208。然後，如第13圖(a)所示，從高濃度p型雜質擴散源 206之上形成背面側介電質層209。然後，如第13圖(b)所示，使高濃度p型雜質擴散源206之上的背面側介電質層209b及高濃度p型雜質擴散源206掀離來形成開口h。高濃度p型雜質擴散源206上以外的背面側介電質層209a會殘留。然後，如第13圖(c)所示，在受光面200A形成介電質層210、及由氮化矽膜所構成之抗反射膜211來作為鈍化膜。最後，在掀離後得到的開口h形成正電極213，以及在受光面200A側形成負電極212，而完成第10圖(a)及(b)所示之太陽電池。上述的受光面200A側的負電極212係由柵電極212G及匯流電極212B所構成。上述的背面200B側的正電極213也由與受光面200A側相對應之柵電極及匯流電極所構成。 In the fourth embodiment, a p-type single crystal germanium substrate 200 is used instead of the n-type single crystal germanium substrate 100. Therefore, the conductivity type is almost the same as that of the first embodiment, and therefore detailed description thereof will be omitted. In the method of manufacturing the solar cell of the fourth embodiment, as shown in Fig. 12(a), an n-type impurity diffusion layer 203 as a second conductivity type semiconductor layer is formed on the light-receiving surface 200A side of the p-type single crystal germanium substrate 200. Then, as shown in Fig. 12(b), a p-type impurity diffusion source 205 for forming a low-concentration p-type impurity diffusion layer 204 is formed on the rear surface 200B of the p-type single crystal germanium substrate 200. Then, the high-concentration p-type impurity diffusion source 206 is formed into a comb-like pattern and dried, and then sent to a diffusion furnace. Then, as shown in Fig. 12(c), impurities are diffused from the high-concentration p-type impurity diffusion source 206 in a mixed gas atmosphere of nitrogen and oxygen to form a high-concentration p-type impurity diffusion layer 207 and a thermal oxide film 208. Then, as shown in Fig. 13(a), from a high concentration p-type impurity diffusion source A back side dielectric layer 209 is formed over 206. Then, as shown in FIG. 13(b), the back side dielectric layer 209b and the high concentration p type impurity diffusion source 206 on the high concentration p-type impurity diffusion source 206 are separated to form an opening h. The back side dielectric layer 209a other than the high concentration p-type impurity diffusion source 206 remains. Then, as shown in FIG. 13(c), a dielectric layer 210 and an anti-reflection film 211 made of a tantalum nitride film are formed on the light-receiving surface 200A as a passivation film. Finally, the opening h obtained after the detachment forms the positive electrode 213, and the negative electrode 212 is formed on the side of the light receiving surface 200A, and the solar cell shown in Figs. 10(a) and (b) is completed. The negative electrode 212 on the light-receiving surface 200A side described above is composed of a gate electrode 212G and a bus electrode 212B. The positive electrode 213 on the side of the back surface 200B described above is also constituted by a gate electrode and a bus electrode corresponding to the side of the light receiving surface 200A.

接著，在以下詳細說明實施形態4之太陽電池之製造程序中之與實施形態1不同之點。如第12圖(a)所示，進行步驟S200，在p型單晶矽基板200的受光面200A上形成n型雜質擴散層203。此工序係以使用POCl3之氣相反應、或使用PH3之APCVD法形成PSG膜201後，使磷熱擴散。亦可藉由離子植入將磷打入，然後使磷熱擴散。 Next, a point different from the first embodiment in the manufacturing procedure of the solar cell of the fourth embodiment will be described in detail below. As shown in Fig. 12(a), in step S200, an n-type impurity diffusion layer 203 is formed on the light-receiving surface 200A of the p-type single crystal germanium substrate 200. In this step, the PSG film 201 is formed by a gas phase reaction using POCl 3 or an APCVD method using PH 3 , and then the phosphorus is thermally diffused. Phosphorus can also be driven by ion implantation, and then the phosphorus is thermally diffused.

在p型單晶矽基板200的背面200B上，如第12圖(b)所示，進行步驟S201來形成低濃度p型雜質擴散層204。此工序係以使用BBr3氣相反應、或使用B2H6之APCVD等之氣相沉積法形成作為p型雜質擴散源205之BSG膜後，使硼熱擴散。 On the back surface 200B of the p-type single crystal germanium substrate 200, as shown in Fig. 12(b), step S201 is performed to form the low-concentration p-type impurity diffusion layer 204. In this step, a BSG film as a p-type impurity diffusion source 205 is formed by a vapor phase deposition method using BBr 3 gas phase reaction or APCVD using B 2 H 6 or the like, and then boron is thermally diffused.

利用氫氟酸將BSG膜去除後，進行步驟 S202在所形成的低濃度p型雜質擴散層204上的一部分形成高濃度p型雜質擴散源206。然後，如第12圖(c)所示，進行步驟S203在擴散爐中進行熱擴散來形成高濃度p型雜質擴散層207。此時也與實施形態1至3一樣將氧氣導入擴散爐內來形成熱氧化膜。 After removing the BSG film by hydrofluoric acid, the steps are performed. S202 forms a high-concentration p-type impurity diffusion source 206 on a portion of the formed low-concentration p-type impurity diffusion layer 204. Then, as shown in Fig. 12(c), the high-concentration p-type impurity diffusion layer 207 is formed by performing thermal diffusion in the diffusion furnace in step S203. At this time, oxygen gas was introduced into the diffusion furnace in the same manner as in the first to third embodiments to form a thermal oxide film.

然後，如第13圖(a)所示，進行步驟S204在低濃度p型雜質擴散層204及高濃度p型雜質擴散源206之上形成背面側介電質層209。背面側介電質層209係由低濃度p型雜質擴散層204上之背面側介電質層209a及高濃度p型雜質擴散源206之上的背面側介電質層209b所構成。背面側介電質層209係採用相對於p型雜質擴散層具有負的固定電荷之氧化鋁膜(尤其是具有高鈍化效果，以例如ALD法形成之氧化鋁膜)與以電漿CVD法形成氮化矽膜之積層結構。 Then, as shown in FIG. 13(a), the back side dielectric layer 209 is formed on the low concentration p-type impurity diffusion layer 204 and the high concentration p-type impurity diffusion source 206 in step S204. The back side dielectric layer 209 is composed of a back side dielectric layer 209a on the low concentration p-type impurity diffusion layer 204 and a back side dielectric layer 209b on the high concentration p-type impurity diffusion source 206. The back side dielectric layer 209 is an aluminum oxide film having a negative fixed charge with respect to the p-type impurity diffusion layer (especially an aluminum oxide film having a high passivation effect, for example, formed by an ALD method) and formed by a plasma CVD method. The laminated structure of the tantalum nitride film.

然後，如第13圖(b)所示，進行使高濃度p型雜質擴散源206掀離而開口之步驟S205，以濕式蝕刻將高濃度p型雜質擴散源206及位於其上之背面側介電質層209b去除。此處，會殘留高濃度p型雜質擴散源206上以外的背面側介電質層209a。 Then, as shown in FIG. 13(b), step S205 is performed in which the high-concentration p-type impurity diffusion source 206 is separated and opened, and the high-concentration p-type impurity diffusion source 206 and the back side located thereon are wet-etched. The dielectric layer 209b is removed. Here, the back side dielectric layer 209a other than the high concentration p-type impurity diffusion source 206 remains.

然後，如第13圖(c)所示，進行步驟S206在受光面的n型雜質擴散層203上形成介電質層210。介電質層210係採用例如氧化矽膜。在介電質層210之上形成氮化矽膜等之抗反射膜211。 Then, as shown in Fig. 13(c), the dielectric layer 210 is formed on the n-type impurity diffusion layer 203 on the light receiving surface in step S206. The dielectric layer 210 is made of, for example, a hafnium oxide film. An anti-reflection film 211 such as a tantalum nitride film is formed on the dielectric layer 210.

最後，進行步驟S207，在p型單晶矽基板 200的受光面200A及背面200B分別形成負電極212及正電極213，完成如第10圖(a)及(b)所示之太陽電池。在負電極212方面係使用含有銀及玻璃粒子之糊，在正電極213方面係使用含有鋁、或鋁及銀之糊。 Finally, step S207 is performed on the p-type single crystal germanium substrate. The light-receiving surface 200A and the back surface 200B of 200 form the negative electrode 212 and the positive electrode 213, respectively, and the solar cells shown in Figs. 10(a) and (b) are completed. A paste containing silver and glass particles is used for the negative electrode 212, and a paste containing aluminum or aluminum and silver is used for the positive electrode 213.

本實施形態也會產生與實施形態1一樣之效果，但在使用p型單晶矽基板200之p型單元(cell)之情況，與n型單元相比較其基板較便宜，所以具有可減低製造成本之優點。 This embodiment also has the same effect as that of the first embodiment. However, when a p-type cell of the p-type single crystal germanium substrate 200 is used, since the substrate is cheaper than the n-type cell, the manufacturing can be reduced. The advantage of cost.

實施形態5. Embodiment 5.

以下，參照圖式來說明實施形態5。第14圖係顯示以本發明的實施形態5之太陽電池之製造方法形成的太陽電池之剖面圖，其中(a)為上視圖，(b)為(a)的C-C剖面圖。第15圖係顯示實施形態5之太陽電池之製造方法之流程圖，第16圖(a)至(c)及第17圖(a)至(c)係顯示實施形態5之太陽電池之製造方法之各工序剖面圖。 Hereinafter, Embodiment 5 will be described with reference to the drawings. Figure 14 is a cross-sectional view showing a solar cell formed by the method for producing a solar cell according to Embodiment 5 of the present invention, wherein (a) is a top view and (b) is a C-C cross-sectional view of (a). 15 is a flow chart showing a method of manufacturing a solar cell according to a fifth embodiment, and FIGS. 16(a) to (c) and 17 (a) to (c) are views showing a method of manufacturing a solar cell according to a fifth embodiment. A cross-sectional view of each process.

實施形態5的特徵係在於：製作成在背面配置射極(emitter)層，在受光面配置背面電場層而成之背面射極(back emitter)結構。因為與實施形態1只有在形成各層之面不同，所以省略詳細的說明。第15圖之流程圖也一樣。實施形態5之太陽電池之製造方法，係如第16圖(a)所示，在n型單晶矽基板100的背面100B側形成作為第二導電型半導體層之p型雜質擴散層103。然後如第16圖(b)所示，在n型單晶矽基板100的受光面100A上形成低濃度 n型雜質擴散層104。然後，形成n型雜質擴散源106，且如第16圖(c)所示，在氮氣與氧氣之混合氣體環境下使雜質從n型雜質擴散源106擴散來形成高濃度n型雜質擴散層107及熱氧化膜108。然後，如第17圖(a)所示，從n型雜質擴散源106之上形成背面側介電質層109。在n型雜質擴散源106之上形成高濃度n型雜質擴散源106上的背面側介電質層109b，在熱氧化膜108上形成高濃度n型雜質擴散源106上以外的背面側介電質層109a。然後，如第17圖(b)所示，將高濃度n型雜質擴散源106上的背面側介電質層109b及n型雜質擴散源106掀離來形成開口h。n型雜質擴散源106上以外的背面側介電質層109a會殘留。然後，如第17圖(c)所示，在背面100B形成作為鈍化膜之介電質膜110、及由氮化矽膜所構成之抗反射膜111。最後，在背面100B側形成正電極112，在受光面100A側之掀離後得到的開口h形成負電極113，而完成第14圖(a)及(b)所示之太陽電池。如此在受光面100A側形成由柵電極113G及匯流電極113B所構成之負電極113，在背面100B側也形成由與受光面100A側相對應之柵電極及匯流電極所構成之正電極112。 The fifth embodiment is characterized in that a back emitter structure in which an emitter layer is disposed on the back surface and a back surface electric field layer is disposed on the light receiving surface is formed. Since the first embodiment differs from the first embodiment in that the layers are formed, a detailed description thereof will be omitted. The flow chart of Figure 15 is the same. In the method of manufacturing a solar cell according to the fifth embodiment, as shown in Fig. 16(a), a p-type impurity diffusion layer 103 as a second conductivity type semiconductor layer is formed on the back surface 100B side of the n-type single crystal germanium substrate 100. Then, as shown in FIG. 16(b), a low concentration is formed on the light receiving surface 100A of the n-type single crystal germanium substrate 100. The n-type impurity diffusion layer 104. Then, an n-type impurity diffusion source 106 is formed, and as shown in FIG. 16(c), impurities are diffused from the n-type impurity diffusion source 106 in a mixed gas atmosphere of nitrogen and oxygen to form a high-concentration n-type impurity diffusion layer 107. And a thermal oxide film 108. Then, as shown in Fig. 17 (a), the back side dielectric layer 109 is formed from the n-type impurity diffusion source 106. The back side dielectric layer 109b on the high concentration n-type impurity diffusion source 106 is formed on the n-type impurity diffusion source 106, and the back side dielectric other than the high concentration n-type impurity diffusion source 106 is formed on the thermal oxide film 108. Mass layer 109a. Then, as shown in FIG. 17(b), the back side dielectric layer 109b and the n-type impurity diffusion source 106 on the high-concentration n-type impurity diffusion source 106 are separated to form an opening h. The back side dielectric layer 109a other than the n-type impurity diffusion source 106 remains. Then, as shown in FIG. 17(c), a dielectric film 110 as a passivation film and an anti-reflection film 111 made of a tantalum nitride film are formed on the back surface 100B. Finally, the positive electrode 112 is formed on the side of the back surface 100B, and the opening electrode 113 is formed on the side of the light-receiving surface 100A to form the negative electrode 113, and the solar cell shown in Figs. 14(a) and (b) is completed. In this way, the negative electrode 113 composed of the gate electrode 113G and the bus electrode 113B is formed on the light-receiving surface 100A side, and the positive electrode 112 composed of the gate electrode and the bus electrode corresponding to the light-receiving surface 100A side is also formed on the back surface 100B side.

本實施形態也會產生與實施形態1一樣之效果，但因為在背面形成射極層，所以可不用考慮形成於射極上的柵電極的遮光損失。因此，可將柵電極形成為窄節距(pitch)化，可實現射極層之高電組化，所以具有可使鈍化效果提高之優點。另外，在受光面配置n型的背面電 場層之情況，與將高濃度層形成得比電極寬之情況相比較，本發明之結構中的光吸收損失(light absorbing loss)較小，所以短路電流會提高。負電極的形成方法除了使用銀糊之印刷法之外還可採用光誘導鍍覆法(light induced plating)。此情況，因為可使位於受光面側的負電極細線化，所以具有遮光損失(light shielding loss)低，可使短路電流提高之優點。 Also in this embodiment, the same effect as in the first embodiment is produced. However, since the emitter layer is formed on the back surface, it is not necessary to consider the light-shielding loss of the gate electrode formed on the emitter. Therefore, the gate electrode can be formed into a narrow pitch, and the high-electrochemical grouping of the emitter layer can be realized, so that the passivation effect can be improved. In addition, the n-type back surface is arranged on the light receiving surface. In the case of the field layer, the light absorbing loss in the structure of the present invention is small as compared with the case where the high concentration layer is formed wider than the electrode, so the short-circuit current is increased. The method of forming the negative electrode may employ light induced plating in addition to the printing method using a silver paste. In this case, since the negative electrode located on the light-receiving surface side can be thinned, there is an advantage that the light shielding loss is low and the short-circuit current can be improved.

前述實施形態1至5中，開口h的形狀係如第18圖中所示的背面側一般，形成為與位於受光面側之正電極112、負電極212平行，且寬度與位於受光面側之正電極112、負電極212相同程度之線狀。另外，位於背面側之負電極113、正電極2123係形成為比位於受光面側之正電極112、負電極212寬若干之線狀。第18圖之A-A剖面圖係與第1圖(b)、第5圖、第10圖(b)相當。 In the first to fifth embodiments, the shape of the opening h is generally the back surface side as shown in FIG. 18, and is formed in parallel with the positive electrode 112 and the negative electrode 212 on the light-receiving surface side, and has a width and a light-receiving surface side. The positive electrode 112 and the negative electrode 212 are linear in the same degree. Further, the negative electrode 113 and the positive electrode 2123 located on the back side are formed in a line shape somewhat wider than the positive electrode 112 and the negative electrode 212 on the light-receiving surface side. The A-A cross-sectional view of Fig. 18 corresponds to Fig. 1 (b), Fig. 5, and Fig. 10 (b).

又，在前述實施形態1至5中，亦可如第19圖中所示的變形例一般，將開口h的形狀形成為與位於受光面側之正電極112、負電極212平行，且由具有與正電極112、負電極212相同程度的直徑之點(dot)狀圖案相隔著間隔而排列成之線狀。另外，位於背面側之負電極113、正電極2123係形成為比正電極112、負電極212的寬度寬若干之線狀。第19圖之A-A剖面圖係與第1圖(b)、第5圖、第10圖(b)相當。 Further, in the first to fifth embodiments, as in the modification shown in Fig. 19, the shape of the opening h may be formed to be parallel to the positive electrode 112 and the negative electrode 212 on the light-receiving surface side, and may have A dot pattern having the same diameter as the positive electrode 112 and the negative electrode 212 is arranged in a line shape with a space therebetween. Further, the negative electrode 113 and the positive electrode 2123 on the back side are formed in a line shape which is wider than the width of the positive electrode 112 and the negative electrode 212. The A-A cross-sectional view of Fig. 19 corresponds to Fig. 1 (b), Fig. 5, and Fig. 10 (b).

根據如上述之構成，高濃度n型雜質擴散層107係以形成為剖面點狀之方式排列。而且，作為第一雜 質擴散層之高濃度n型雜質擴散層107，係從基板的背面100B的一部分向受光面100A方向伸長。另外，位於背面側之負電極113係在開口h內與高濃度n型雜質擴散層107接觸，而且突出於覆蓋在背面100B上之為背面側介電質層109a之氮化矽膜的一部分上。此時，為了容易從各接觸收集電力，而將電極形成為線狀，且將各接觸電性連接起來。如此，就可利用一次的印刷形成集電電極。實施形態1至4之情況，因為背面電場層係形成於與受光面相反的一側，所以亦可在背面的全面形成電極。 According to the configuration described above, the high-concentration n-type impurity diffusion layer 107 is arranged so as to have a cross-sectional shape. Moreover, as the first miscellaneous The high-concentration n-type impurity diffusion layer 107 of the mass diffusion layer is elongated from a part of the back surface 100B of the substrate toward the light-receiving surface 100A. Further, the negative electrode 113 on the back side is in contact with the high-concentration n-type impurity diffusion layer 107 in the opening h, and protrudes over a portion of the tantalum nitride film which is the back surface-side dielectric layer 109a over the back surface 100B. . At this time, in order to easily collect electric power from each contact, the electrodes are formed in a line shape, and the contacts are electrically connected. Thus, the collector electrode can be formed by one printing. In the first to fourth embodiments, since the back surface electric field layer is formed on the side opposite to the light receiving surface, the electrode can be formed on the entire back surface.

因此，可使高濃度擴散層，亦即n型雜質擴散層107的面積減小。如此可抑制高濃度部之再結合損失，特性會因而提高。 Therefore, the area of the high concentration diffusion layer, that is, the n-type impurity diffusion layer 107 can be reduced. In this way, the recombination loss of the high concentration portion can be suppressed, and the characteristics are thus improved.

另外，亦可得到將第19圖所示的剖面點狀的高濃度n型雜質擴散層107分佈在基板的背面100B全面，且使點狀的負電極113在開口h內與高濃度n型雜質擴散層107接觸，而且突出於覆蓋在背面100B上之為背面側介電質層109a之氮化矽膜的一部分上，另一方面在同一面側之背面100B上形成與p型雜質擴散層接觸的正電極之背面取出型的太陽電池結構。 Further, it is also possible to distribute the high-concentration n-type impurity diffusion layer 107 having the cross-sectional shape shown in Fig. 19 over the entire back surface 100B of the substrate, and to make the dot-shaped negative electrode 113 in the opening h and the high-concentration n-type impurity. The diffusion layer 107 is in contact with and protrudes from a portion of the tantalum nitride film which is the back surface side dielectric layer 109a over the back surface 100B, and forms a contact with the p-type impurity diffusion layer on the back surface 100B of the same surface side. The back side of the positive electrode is taken out of the solar cell structure.

如以上所說明的，根據實施形態1至5，在高濃度雜質層的擴散工序中，只將氧氣供給至擴散爐中，就可容易地形成可靠性高之選擇摻雜結構。而且依據擴散溫度、或擴散環境氣體等之擴散條件，調整氧化環境氣體，可進行擴散控制及控制氧化條件，所以可得到操作性非常 好且高精度的電極接觸結構。因此，可提供高效率的太陽電池。 As described above, according to the first to fifth embodiments, in the diffusion step of the high-concentration impurity layer, only the oxygen gas is supplied to the diffusion furnace, and the highly selective doping structure can be easily formed. Further, depending on the diffusion temperature or the diffusion conditions such as the diffusion of the ambient gas, the oxidation of the ambient gas can be adjusted, and the diffusion control and the oxidation control conditions can be performed, so that the operability is very high. Good and high precision electrode contact structure. Therefore, a highly efficient solar cell can be provided.

又，在前述實施形態1至5中，雖使用n型單晶矽基板100及p型單晶矽基板200來作為結晶系半導體基板，但不限於單晶矽亦可為多晶矽或微晶矽。此外，還可為SiC等之矽系基板、GaAs等之化合物半導體基板。 Further, in the above-described first to fifth embodiments, the n-type single crystal germanium substrate 100 and the p-type single crystal germanium substrate 200 are used as the crystalline semiconductor substrate, but the polycrystalline germanium or the microcrystalline germanium may be used without being limited to the single crystal germanium. Further, it may be a ruthenium substrate such as SiC or a compound semiconductor substrate such as GaAs.

以上實施形態所揭示的構成，表示的只是本發明的內容的一例，除此之外，還可與別的公知的技術相組合，以及可在未脫離本發明的主旨之範圍內將構成的一部分予以省略或加以變更。 The configuration disclosed in the above embodiments is merely an example of the content of the present invention, and may be combined with other known techniques, and a part of the configuration may be made without departing from the gist of the present invention. Omitted or changed.

100‧‧‧n型單晶矽基板 100‧‧‧n type single crystal germanium substrate

100A‧‧‧受光面 100A‧‧‧Glossy surface

100B‧‧‧背面 100B‧‧‧back

101‧‧‧BSG膜 101‧‧‧BSG film

102‧‧‧NSG膜 102‧‧‧NSG film

103‧‧‧p型雜質擴散層 103‧‧‧p type impurity diffusion layer

104‧‧‧低濃度n型雜質擴散層 104‧‧‧Low concentration n-type impurity diffusion layer

106‧‧‧高濃度n型雜質擴散源 106‧‧‧High concentration n-type impurity diffusion source

107‧‧‧高濃度n型雜質擴散層 107‧‧‧High concentration n-type impurity diffusion layer

108‧‧‧熱氧化膜 108‧‧‧ Thermal Oxide Film

109‧‧‧背面側介電質層 109‧‧‧Back side dielectric layer

109a‧‧‧高濃度n型雜質擴散源上以外之背面側介電質層 109a‧‧‧ Back side dielectric layer other than high concentration n-type impurity diffusion source

109b‧‧‧高濃度n型雜質擴散源上之背面側介電質層 109b‧‧‧Backside dielectric layer on a high concentration n-type impurity diffusion source

110‧‧‧受光面側介電質層 110‧‧‧Lighted side dielectric layer

111‧‧‧抗反射膜 111‧‧‧Anti-reflective film

h‧‧‧開口 H‧‧‧ openings

Claims (10)

一種太陽電池之製造方法，依序包含：在具有第一導電型之結晶系的半導體基板的第一主面上的一部分形成含有第一導電型的雜質之擴散源之工序；將前述半導體基板升溫至擴散溫度，使前述第一導電型的雜質從前述擴散源擴散到前述半導體基板中，以形成第一雜質擴散層之擴散工序；在前述半導體基板的第一主面上及前述擴散源上形成介電質層之工序；將前述擴散源與位於前述擴散源上之介電質層一起掀離，以形成開口之工序；以及在前述開口內形成與前述第一雜質擴散層接觸之電極之工序；其中，前述擴散工序包含：將氧供給至前述半導體基板，而在前述半導體基板的第一主面上形成熱氧化膜之工序。 A method for manufacturing a solar cell, comprising: a step of forming a diffusion source containing impurities of a first conductivity type on a portion of a first main surface of a semiconductor substrate having a first conductivity type crystal system; and heating the semiconductor substrate a diffusion step of diffusing a first conductivity type impurity from the diffusion source into the semiconductor substrate to form a diffusion process of the first impurity diffusion layer; forming a first main surface of the semiconductor substrate and the diffusion source a process of forming a dielectric layer by separating the diffusion source from a dielectric layer on the diffusion source to form an opening; and forming an electrode in contact with the first impurity diffusion layer in the opening The diffusion step includes a step of supplying oxygen to the semiconductor substrate and forming a thermal oxide film on the first main surface of the semiconductor substrate. 如申請專利範圍第1項所述之太陽電池之製造方法，其中，前述擴散工序包含：在使前述半導體基板升溫至前述擴散溫度的途中，在到達前述擴散溫度之前，將氧供給至前述半導體基板之工序。 The method for producing a solar cell according to claim 1, wherein the diffusing step includes supplying oxygen to the semiconductor substrate before reaching the diffusion temperature while raising the temperature of the semiconductor substrate to the diffusion temperature. Process. 如申請專利範圍第1項所述之太陽電池之製造方法，其 中，前述擴散工序包含：在到達前述擴散溫度後，將氧供給至擴散中的前述半導體基板之工序。 A method of manufacturing a solar cell according to claim 1, wherein The diffusion step includes a step of supplying oxygen to the diffusion semiconductor substrate after reaching the diffusion temperature. 如申請專利範圍第1項所述之太陽電池之製造方法，其中，前述形成擴散源之工序係在前述半導體基板的第一主面直接形成擴散源之工序。 The method for producing a solar cell according to claim 1, wherein the step of forming the diffusion source is a step of directly forming a diffusion source on the first main surface of the semiconductor substrate. 如申請專利範圍第1項所述之太陽電池之製造方法，其包含：在前述半導體基板的前述第一主面形成與前述第1雜質擴散層相同導電型且雜質濃度比前述第一雜質擴散層低之第二雜質擴散層之工序。 The method for producing a solar cell according to the first aspect of the invention, comprising: forming, on the first main surface of the semiconductor substrate, a conductivity type similar to that of the first impurity diffusion layer; and an impurity concentration ratio of the first impurity diffusion layer A process of lowering the second impurity diffusion layer. 如申請專利範圍第5項所述之太陽電池之製造方法，其中，前述形成第二雜質擴散層之工序，係在形成前述擴散源之工序之前實施。 The method for producing a solar cell according to claim 5, wherein the step of forming the second impurity diffusion layer is performed before the step of forming the diffusion source. 如申請專利範圍第1項所述之太陽電池之製造方法，其中，前述介電質層係氮化矽膜、氧化鋁膜、非晶矽膜、微晶矽膜、氮氧化矽膜、及該等膜的積層結構體之任一者。 The method for producing a solar cell according to the first aspect of the invention, wherein the dielectric layer is a tantalum nitride film, an aluminum oxide film, an amorphous germanium film, a microcrystalline germanium film, a hafnium oxynitride film, and the like Any one of the laminated structures of the film. 如申請專利範圍第1項所述之太陽電池之製造方法，其中，前述掀離工序係藉由使雷射束通過前述介電質層 而照射至前述擴散源而進行。 The method for manufacturing a solar cell according to claim 1, wherein the separating step is performed by passing a laser beam through the dielectric layer The irradiation is performed on the diffusion source. 如申請專利範圍第1項所述之太陽電池之製造方法，其中，前述掀離工序，係藉由濕式蝕刻而進行。 The method for producing a solar cell according to the first aspect of the invention, wherein the removing step is performed by wet etching. 如申請專利範圍第1項所述之太陽電池之製造方法，其中，前述半導體基板係結晶系矽基板。 The method for producing a solar cell according to the first aspect of the invention, wherein the semiconductor substrate is a crystalline germanium substrate.
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