201013772 九、發明說明： 【發明所屬之技術領域】 本發明係關於-種⑦基板之勤〗方法，且特別係關於一 種在矽基板之表面上蝕刻出複數個奈米結構之餘刻方法。 【先前技術】 太陽能電池是一種能量轉換的光電元件，它是經由太陽 Φ 光照射後，把光的能量轉換成電能，因此這種光電元件稱為 太陽能電池。由於太陽能電池能夠將發自一光源(例如，太陽 光)的光能轉換成電能以操控例如，計算機、電腦、加熱器… 等電子裝置，所以太陽能電池已被廣泛地使用。 請參閱圖一。圖一係緣示一習知的石夕基太陽能電池i其 層狀的堆豐結構之截面視圖。如圖一所示，太陽能電池1主 要包含石夕基板10、表面純化/抗反射層12以及電極14。石夕基 板10包含一淺層的P-N接面1〇〇。表面鈍化/抗反射層12的 功能在於減少入射光的反射機率，即提高矽基板丨〇的光吸收 φ 率以增進石夕基太陽能電池1的光電轉換效率。 一般來說，除了表面鈍化/抗反射層12外，太陽能電池1 之光照面’即圖一中矽基板10之上表面102都會先經過表面 粗糖化處理(surface texturing treatment)，以更進一步地減少入 射光的反射率。 於先前技術中，Shinji Yae等人於【Electrochemistry Communications 5 (2003) 632-636】中發表的「Formation of porous silicon by metal particle enhanced chemical etching in HF solution and its application for efficient solar cells」即揭露了一 種多孔性(porous)石夕基板的製造方法：將表面鑛有一白金(Pt) 201013772 薄層的矽晶圓沉浸於氫氟酸(HF)溶液中，毋須施加偏壓或氧 化劑即可製成。另外，Kui-Qing Peng等人於【Adv. Mater. 2002, 14, No. 16, Aug. 16, pll64-1167】中發表的「Synthesis of201013772 IX. OBJECTS OF THE INVENTION: TECHNICAL FIELD The present invention relates to a method for 7 substrates, and in particular to a method for etching a plurality of nanostructures on a surface of a germanium substrate. [Prior Art] A solar cell is an energy-converting photovoltaic element which converts light energy into electric energy after being irradiated by sunlight Φ light, and thus such a photovoltaic element is called a solar cell. Since solar cells are capable of converting light energy from a light source (e.g., sunlight) into electrical energy to manipulate electronic devices such as computers, computers, heaters, etc., solar cells have been widely used. Please refer to Figure 1. Figure 1 is a cross-sectional view showing a layered stack structure of a conventional Shih-Xi solar cell. As shown in Fig. 1, the solar cell 1 mainly comprises a stone substrate 10, a surface purification/antireflection layer 12, and an electrode 14. The Shihki board 10 includes a shallow P-N junction 1〇〇. The function of the surface passivation/anti-reflection layer 12 is to reduce the probability of reflection of incident light, i.e., to increase the light absorption φ ratio of the ruthenium substrate 以 to enhance the photoelectric conversion efficiency of the Shihua solar cell 1. In general, in addition to the surface passivation/anti-reflection layer 12, the illumination surface of the solar cell 1 , that is, the upper surface 102 of the substrate 10 in FIG. 1 , is first subjected to surface texturing treatment to further reduce The reflectivity of the incident light. In the prior art, "Formation of porous silicon by metal particle enhanced chemical etching in HF solution and its application for efficient solar cells", published by Electroji Yae et al., [Electrochemistry Communications 5 (2003) 632-636, discloses a A method for manufacturing a porous stone substrate: a platinum alloy (Pt) 201013772 surface layer is immersed in a hydrofluoric acid (HF) solution, and a bias or an oxidizing agent is not required. In addition, "Synthesis of" by Kui-Qing Peng et al., [Adv. Mater. 2002, 14, No. 16, Aug. 16, pll 64-1167]
Large-Area Silicon Nanowire Arrays via Self-Assembling NanoelectiOchemistry」揭露了一種表面形成奈米線陣列的矽 基板之製造方法。 不論是多孔性矽基板或表面具有奈米線陣列的矽基板， 皆能夠減少入射光的反射率。理論上，若矽基板上同時形成 ❹ 奈米洞及奈米線，則可以更有效地提高石夕基板之抗反射率。 然而，習知的技術尚未揭露此種矽基板的製造方法。 【發明内容】 本發明之一範疇在於提供一種蝕刻矽基板之方法。 根據本發明之-具體實酬，該方法藉由—侧液，敍 基板之表面，致使矽基板之表面形成複數個奈米結構。 二’侧液為氫氟酸㈣:容液、水、硝酸銀(AgN〇3)溶液及 匕氧化氫(H2〇2)溶液依照一預定比例混合所得之混合液。The Large-Area Silicon Nanowire Arrays via Self-Assembling Nanoelecti Ochemistry discloses a method of manufacturing a ruthenium substrate having a surface-formed nanowire array. Whether it is a porous ruthenium substrate or a ruthenium substrate having a nanowire array on its surface, the reflectance of incident light can be reduced. In theory, if the nano-holes and the nanowires are simultaneously formed on the substrate, the anti-reflection rate of the stone substrate can be more effectively improved. However, conventional techniques have not disclosed a method of manufacturing such a tantalum substrate. SUMMARY OF THE INVENTION One aspect of the present invention is to provide a method of etching a germanium substrate. In accordance with the present invention, the method utilizes a side liquid to describe the surface of the substrate such that a plurality of nanostructures are formed on the surface of the substrate. The two side liquid is hydrofluoric acid (four): a mixed liquid obtained by mixing a liquid, water, silver nitrate (AgN〇3) solution and hydrogen peroxide (H2〇2) solution in a predetermined ratio.
I -A. i 一. *»- ^本，發明之另—具體實施例’該等奈米結構係藉由-I - A. i I. *»- ^This, another embodiment of the invention - the nanostructures are by -
液、 得之〜w… ，發^之# !!脅在於提供―種#刻液，適用於兹亥4一Liquid, get it ~w..., send ^之#!! The threat is to provide "seed #刻液, apply to Zhai 4 one
7 201013772 合液。 以下的發明詳述及所 關於本發明之優點與精神可以藉由 附圖式传到進—步的瞭解。 【實施方式】 ❹ ❿ 本發明提供-種侧石夕基板之方法，用以在石夕基板 =七姓刻出複數個奈米結構以提高對於入射光之抗反射率二 陽侧方法適用於製造具有高度光電轉換效 、於實際躺巾’本發日狀蝴方法顧於—單晶砍基板 或一多晶矽基板，但不以此為限。為充份了解本發明之 想，以下列舉一實施例以詳加說明。 、首先，製備氫氟酸溶液、水、硝酸銀溶液及過氧化氫溶 液。需注意的是，上述之溶液各別具有一預定的濃度。於此 實施例中，氫氟酸溶液之濃度大致上為49%，硝酸銀溶液之 濃度大致上為G.1M，㈣氧化聽液之濃度规上為39%。 之後，在一預定溫度下將濃度49%的氫氟酸溶液、濃度 0.1Μ的硝酸銀溶液、濃度39%的過氧化氳溶液及水依照一預 疋比例混合均勻以配製成一混合液。該混合液即可作為用以 蝕刻矽基板之蝕刻液。於一較佳具體實施例中，氫氟酸溶 液、水、硝'酸銀溶液及過氧化氫溶液之比例可以是2〇 ·· 4〇 : 1 : 4。另外，混合液可以在溫度大致上為2〇t：下配製而成。 接著，藉由該蝕刻液對矽基板之表面進行蝕刻。實務 上，矽基板可以浸泡於蝕刻液中，即以化學溼式蝕刻方式進 行。於此實施例中，矽基板係浸泡於上述之混合液中並且對 石夕基板之表面餘刻大致上為5分鐘的時間，致使石夕基板之表 8 201013772 面开/成複數個奈米結構。另外要強調的是，本發明並不需 :貝先沉積-金屬層於魏板之表面上再進行侧， 製造工時及成本。 請參閱圖二(a)、圖二(b)、圖三⑻及圖三(b)。圖二⑻及 圖=(b)係分別為根據本發明之單晶矽基板之頂視掃描式電子 顯微鏡(S瞻ing Electron紙臟。凡SEM)圖片及側視SEm 圖片。圖二(a)及圖三(b)係分別為根據本發明之多晶矽基 頂視SEM圖片及側視SEM圖片。 、於此實施例中，不論是單晶矽基板或多晶矽基板，蝕刻 液皆可以同時在基板之表面上侧出複數個奈米洞細〇p㈣ 及複數個奈米線(nanowire或nan〇be均，如圖二⑻至圖三 所不。藉此，當入射光投射至矽基板之表面上後，複數個奈 米洞及複數個奈米線可以大幅地減少入射光反射的機率，以 充份提昇石夕基板的光線吸收率。 請參=圖四(a)及圖四(b)。圖四(a)及圖四(b)係分別為根據 本發明之單晶矽基板之圖片及一般矽基板之圖片，用以呈現 並對照兩者之光反射情況。明顯地，根據本發明之單晶矽美 板在視覺上近乎呈現黑色，即代表入射光幾乎由單晶^基& 所吸收，因此具有極佳的抗反射率。 土 另外，請參閱圖五。圖五係繪示量測根據本發明之矽基 板及一般矽基板之光線反射率所得之結果。上方的曲線代^ 一般矽基板對於不同波長的入射光所具有的平均反射率丨下 方的曲線代表根據本發明之矽基板對於不同波長的入射光所 具有的平均反射率。經量測後發現，根據本發明之多晶矽基 板對於波長介於400nm〜lOOOnm之入射光可以具有5%的^ 射率’而根據本發明之單晶矽基;板對於波長介於 400nm〜lOOOnm之入射光的反射率甚至可以低到1%。 ' 201013772 於實際應用中，根據本發明之矽基板在蝕刻過後進一步 可以施以擴散製程以形成p_N接面，接著再經過一熱氧化製 程以將表面純化。 〇月參閱圖六。圖六為以# _pCD(microwave photoconductive decay)測試根據本發明之單晶矽基板的生命週 期所得之實驗結果。需說明的是，圖六為測試經過熱氧化製 程將表面，化後之單晶矽基板而得。由圖六中可得知，根據 本發明之，晶矽基板之有效的生命週期可以超過2〇网。此實 驗結，表示，這個生命週期數值對於厚度小於2卿m的石夕基 板來說是非常足細。另外，若在熱氧化餘後再沉積一表 化層於⑪基板上’例如氮切(秘4)，梦基板的生命週 期能夠更進一步被延長。 根據本發明之另一範疇在於提供一種矽基板，並且矽基 板之^面形成複數個奈米結構。於實際應財，根據本發明 之石夕土板可以是一單晶石夕基板或一多晶石夕基板。 呙兒月的疋4等景米結構係藉由一餘刻液银刻石夕基板 鲁 f表=得。於—具體實施例中，姓刻液為氫氟酸溶液、 容液及過氧城溶驗照—就_混合所得之 '日:二二l於混合液的配製方法及矽基板的蝕刻過程請再參 d實施ί! ’在此便不再贅述。於-較佳具體實施例 半綠=f之上可以被蝕刻出複數個奈米洞及複數個奈 未線，精此以提尚矽基板對入射光的抗反射率。 上據本發明之侧方法㈣树基板之表面 機^米線等，藉此以減少入射光反射的 伤ί什石夕基板的光線吸收率。13此，根據本發明之 換鱗基板非常細於製造财高度光電轉 201013772 述本實施，詳述，希望能更加清楚描 施例來對本發明^ 而並相上述所揭露的較佳具體實 涵蓋各觀Si 地’其目的是希望能 ❹ ❹ 11 201013772 【圖式簡單說明】 之截繪示—基太陽能電池其層㈣堆4結構 視SE==片為根據本發明之單晶雜板之頂 Ο 圖王⑻及圖三〇3)係分別為根據本發㈣ 視SEM圖片及側視SEM圖片。 ㈣系分別為用以呈現光反射情況之根據本 毛明之早曰曰石夕基板之圖片及一般石夕基板之圖片。 圖五係繪示量測根據本發明之矽基板及一般矽基板之光 線反射率所得之結果。 圖為以/z -PCD剛試根據本發明之單晶石夕基板的生命 期所付之實驗結果。 【主要元件符號說明】 12 :表面純化/抗反射層 102 ·上表面 1 :太陽能電池 W :矽基板 14 :電極 100 : P-N 接面 127 201013772 Combined liquid. The following detailed description of the invention and the advantages and spirit of the present invention can be understood by the accompanying drawings. [Embodiment] ❹ ❿ The present invention provides a method for seeding a side stone substrate, which is used to engrave a plurality of nano structures in a stone substrate=seven surname to improve the antireflection rate against incident light. It has a high photoelectric conversion effect, and the method of the present invention is based on a single crystal chopping substrate or a polycrystalline germanium substrate, but is not limited thereto. In order to fully understand the present invention, an embodiment will be described below in detail. First, a hydrofluoric acid solution, water, a silver nitrate solution, and a hydrogen peroxide solution are prepared. It should be noted that the above solutions each have a predetermined concentration. In this embodiment, the concentration of the hydrofluoric acid solution is approximately 49%, the concentration of the silver nitrate solution is approximately G.1M, and (4) the concentration of the oxidized auditory solution is 39%. Thereafter, a 49% hydrofluoric acid solution, a 0.1% silver nitrate solution, a 39% cerium peroxide solution, and water were uniformly mixed at a predetermined temperature to prepare a mixed liquid at a predetermined ratio. This mixture can be used as an etching solution for etching a germanium substrate. In a preferred embodiment, the ratio of the hydrofluoric acid solution, water, the silver nitrate solution, and the hydrogen peroxide solution may be 2 〇 ·· 4 〇 : 1 : 4. In addition, the mixed solution can be prepared at a temperature of approximately 2 〇 t:. Next, the surface of the germanium substrate is etched by the etching liquid. In practice, the tantalum substrate can be immersed in an etchant, i.e., chemically wet etched. In this embodiment, the ruthenium substrate is immersed in the above mixture and the surface of the shixi substrate is substantially 5 minutes, so that the surface of the shixi substrate is open/multiple nanostructures. . In addition, it should be emphasized that the present invention does not require: the bead deposition-metal layer is further performed on the surface of the Wei board, manufacturing man-hours and costs. Please refer to Figure 2 (a), Figure 2 (b), Figure 3 (8) and Figure 3 (b). Fig. 2 (8) and Fig. (b) are respectively a top view scanning electron microscope (S ing Electron paper SEM) picture and a side view SEm picture of the single crystal germanium substrate according to the present invention. Fig. 2(a) and Fig. 3(b) are top view SEM images and side SEM pictures, respectively, of the polycrystalline germanium according to the present invention. In this embodiment, whether it is a single crystal germanium substrate or a polycrystalline germanium substrate, the etching solution can simultaneously form a plurality of nanohole fine p(4) and a plurality of nanowires (nanowire or nanowire) on the surface of the substrate. As shown in Fig. 2 (8) to Fig. 3, after the incident light is projected onto the surface of the ruthenium substrate, a plurality of nano-holes and a plurality of nanowires can greatly reduce the probability of incident light reflection, so as to be sufficient Enhance the light absorption rate of the Shixi substrate. Please refer to Fig. 4(a) and Fig. 4(b). Fig. 4(a) and Fig. 4(b) are respectively pictures and generals of the single crystal germanium substrate according to the present invention. A picture of the substrate is used to present and contrast the light reflections of the two. Obviously, the single crystal enamel plate according to the present invention is visually nearly black, that is, the incident light is absorbed by the single crystal base & Therefore, it has an excellent anti-reflection rate. In addition, please refer to FIG. 5. Figure 5 is a graph showing the results of measuring the light reflectance of the tantalum substrate and the general tantalum substrate according to the present invention. The average inverse of the substrate for incident light of different wavelengths The curve below the radiance 丨 represents the average reflectance of the ruthenium substrate according to the present invention for incident light of different wavelengths. It has been found that the polycrystalline germanium substrate according to the present invention can have incident light having a wavelength between 400 nm and 100 nm. 5% of the transmittance> and the single crystal ruthenium according to the present invention; the reflectance of the plate for incident light having a wavelength between 400 nm and 100 nm can be as low as 1%. ' 201013772 In practical applications, according to the present invention After the etching, the substrate may further be subjected to a diffusion process to form a p_N junction, and then subjected to a thermal oxidation process to purify the surface. See Figure 6 for the month. Figure 6 is a test based on #_pCD(microwave photoconductive decay) according to the present invention. The experimental results obtained from the life cycle of the single crystal germanium substrate. It should be noted that FIG. 6 is a test of the single crystal germanium substrate which has been subjected to a surface treatment by a thermal oxidation process. As can be seen from FIG. The effective life cycle of the wafer substrate can exceed 2 〇. This experimental knot indicates that this life cycle value is for the Shixi substrate with a thickness less than 2 qing m. In addition, if a surface layer is deposited on the 11 substrate after thermal oxidation, for example, nitrogen cutting (secret 4), the life cycle of the dream substrate can be further extended. According to another aspect of the present invention, A ruthenium substrate is provided, and a plurality of nanostructures are formed on the surface of the ruthenium substrate. In actual practice, the shi slate plate according to the present invention may be a single crystal slab substrate or a polycrystalline slab substrate. The 景4 and other smectite structures are obtained by using a liquid engraved silver engraved stone substrate. In the specific embodiment, the surname is hydrofluoric acid solution, liquid and peroxyl city - As for the mixing of the 'Day: 22' in the preparation method of the mixed solution and the etching process of the substrate, please refer to the implementation of ί! ' will not repeat here. In the preferred embodiment, a plurality of nanoholes and a plurality of nanowires can be etched over the semi-green = f, in order to improve the antireflection rate of the substrate by the substrate. According to the side method of the present invention, (4) the surface of the tree substrate, etc., thereby reducing the light absorption rate of the substrate reflected by the incident light. 13 , the scale-changing substrate according to the present invention is very finer than the manufacturing height of the photoelectric conversion 201013772. In detail, it is intended to be more clearly described in the present invention, and the preferred embodiments disclosed above are Viewing the location of Si's purpose is to hope that it can be ❹ 11 201013772 [Simplified illustration of the diagram] The base layer of the solar cell (four) stack 4 structure depends on the SE = = sheet is the top of the single crystal board according to the present invention Figure King (8) and Figure 3〇3) are SEM images and side-view SEM images according to the present (4). (4) The pictures of the early 曰曰石夕 substrate according to the present invention and the picture of the general Shishi substrate are used to present the light reflection. Figure 5 is a graph showing the results of measuring the light reflectance of the germanium substrate and the general germanium substrate according to the present invention. The figure shows the experimental results of the lifetime of the single crystal substrate according to the present invention as /z -PCD. [Main component symbol description] 12: Surface purification/anti-reflection layer 102 · Upper surface 1 : Solar cell W : 矽 substrate 14 : Electrode 100 : P-N junction 12