201007955 九、發明說明： 【發明所屬之技術領域】 本發明關於一種光電轉換元件，特別關於一種表面具 有微結構的光電轉換元件及其製造方法。 j 【先前技術】 為了提升太陽能電池（solar cell)對光線的吸收能力， 一般習知的方法多藉由加大太陽能基板的表面積，以使進 曰 入至太陽能基板的光線增加，或可於太陽能基板的表面上 沉積抗反射層（anti-reflection layer)，以降低太陽能基板 對光線的反射，進而提高進入至太陽能基板内部的光線。 另外，更有部分技術是對太陽能基板進行表面處理（例如 粗糙化處理），使太陽能基板的單位面積可具有較多角度 的入射面，以降低太陽能基板對光線的反射率。 而針對上述的表面處理，習知通常藉由化學蝕刻法以 ❹實現，舉例纟說，藉由濕式姓刻的方法以粗輪化單晶石夕 ^:〇n〇_Sl)的太陽能基板表面。其中，通常使用的姓刻液 氫氧化鉀（KQH)或氫氧灿（Na()H)等驗性溶劑， ^ 濕式_後的單W域能基板表面會因為單晶 、的能力的曰曰格特性而呈現金字塔形狀，藉以增強吸收光線 =’此等技術卻不能沿用到多⑽（pGiy_si)的太 對不ίί s ®主要的原因在於錢式㈣的製程巾，侧液 P的晶粒_速度不同，故多晶料太陽能基板 201007955 表面無法如單晶矽的太陽能基板表面一樣呈現出銳利的 金子塔形狀。因此，對於多晶秒的太陽能基板而言》濕式 蝕刻的表面處理方法並無法有效地提高多晶矽太陽能基 板的光線吸收能力。 、 請參照圖1，為提供一種有效的多晶矽太陽能基板的 表面處理方法，習知技術是以酸性蝕刻液來對多晶矽太陽 能基板1的表面111進行濕式蝕刻。於此，多晶矽太陽能 基板1以一 P型半導體層13及一 N型半導體層11所共同 ® 構成為例說明，並以氳氟酸（HF)為蝕刻液，使多晶矽太 陽能基板1的表面在經過濕式蝕刻後，為具有至少一凹結 構111a及/或凸結構111b的型態，藉以達到表面結構化 (texturization)的效果。 酸性的蝕刻液除了上述的氫氟酸之外，亦可選自硝 酸、硫酸、磷酸、醋酸及其組合。且為了改善多晶矽太陽 能基板1表面的凹結構111a及/或凸結構111b的均勻性， φ 則必須使多晶石夕太陽能基板1經過多次的濕式独刻處理。 不過，如此將導致製程成本的提高、產品良率下降、製程 工時增加等問題。 然而，上述以酸性蝕刻液進行的濕式蝕刻方法雖然可 在多晶矽太陽能基板的表面蝕刻出凹結構及/或凸結構，不 過由於以濕式蝕刻所形成的凹結構及/或凸結構在尺寸上 仍不夠微小，而使得此等結構中依舊具有複數個一定面積 的截面。故當光線入射至此多晶石夕太陽能基板聘，仍會因 為此等截面而使得部分光線被反射，造成多晶矽太陽能基 201007955 板對光線的利用率不佳。 【發明内容】 本發明之目的為提供一種光電轉換元件及其製造方 、法’能降低光電轉換元件的反射率，以提升太陽能基板對 、 光線的利用率。 本發明之目的為提供一種光電轉換元件及其製造方 法，其中光電轉換元件尤適甩於多晶矽的太陽能電池系 ©統。 為達上述目的，依據本發明之一種光電轉換元件包含 一半導體基板以及複數個微結構位於半導體基板的表 面。半導體基板具有一表面，此表面具有至少—凹結構及 /或至少一凸結構。其中，微結構為將複數半導體奈米粒孑 (nano-grade semiconductor particles)形成於表面以作為 遮罩，並藉由蝕刻表面以形成。 ❿ 為達上述目的.，依據本發明之一種光電轉換元件的製 造方法包含以下步驟：提供一半導體基板，半導體基板具 有一表面；於半導體基板的表面形成至少一凹結構及/威多 少一凸結構；提供複數半導體奈米粒子於表面以作為遮 罩；以及蝕刻半導體基板的表面並形成複數個微結構。 -· · 承上所述，因依據本發明之光電轉換元件及其製造方 法，其藉由爭導體奈米粒子以提供奈米級的遮蔽效果’使 得在蝕刻半導體基板的表面時，可形成至少一奈米級的微 結構，與習知技術相較，本發明具有奈米級微結構的半導 201007955 體基板表面能夠具有較低的光線反射率，並提升半導體基 板對光線的利用率。 另外，因為遮罩的材料亦為半導體材料，其製作過程 能與現有的太陽能電池生產技術相匹配，容易量產，成本 : 低廉，並且生產過程中所產生的氫原子對於半導體基板與 ' 界面缺陷可以有純化的效果，而增加光電轉換效率，同時 因為遮罩為寬能隙半導體，即使殘留在元件上，亦不會降 低光電轉換效率。 【實施方式】 以下將參照相關圖式，說明依據本發明較佳實施例之 一種光電轉換元件及其製造方法，其中相同的元件將以相 同的元件符號加以說明。 請參照圖2所示，其為本發明較佳實施例之一種光電 轉換元件的結構示意圖。光電轉換元件包含一半導體基板 φ 2以及複數個微結構211c。半導體基板2具有一表面211， 此表面211具有至少一凹結構211a及/或至少一凸結構 211b;而微結構211c則是位於表面211。以本實施例為例， 微結構211c更位於此等凹绪構211a及/或此等凸結構 211b。其中，微結構211c為利用半導體奈米粒子（圖未顯 示）以作為遮罩，並藉由蝕刻半導體基板2的表面211所 形成。 值得注意的是，上述半導體基板2的材料可為單晶 石夕、非晶石夕（amorphous-和）、多晶石夕及其組合的半導體材 201007955 料’不過本發明尤其適用於由多晶矽半導體材料所構成的 半導體基板2。更詳細來說，半導體基板2的材料可選自 於P型半導體材料、;^型半導體材料及其組合。根據圖2 所示的實施例可知，半導體基板2是由一 P型半導體層幻 、 及一 N型半導體層21所構成。 3 另外，凹結構211a及/或凸結構211b是藉由濕式蝕刻 的製程方式以茲刻半導體基板2的表面211以形成；而相 ❹對=述的凹結構211a及/或凸結構2m，微結構幻& 則是藉由乾式蝕刻及/或濕式蝕刻的製程方式以蝕刻半導 體基板2的表面211，更詳細來說，在形成微結構211c時， 更先在半導體基板2的表面顶上提供複數半導體奈米粒 子（圖未顯示），藉由此些半導體奈米粒子以遮蔽局部的 表面211區域並於其上蝕刻出微結構2Uc。 而就應用層面來說，上述的光電轉換元件可應用於太 陽能電池中。 ' © 上述為本發明所揭露的一種光電轉換元件的結構，以 I則提出一種用以製作出上述光電轉換元件的製造方 法。如圖3所示，製造方法包含步驟S1至步驟％。同時， .為結合每一步驟與其所對應的結構，則請-併參照圖4A 至圖4D所示，其中，圖4A所朱的結構對應至圖3中的步 驟幻、圖4B所示的結構對應至圖3中的步驟幻、圖4c =的結構對應至圖3中的步弊幻、且圖4D所示的結構 ^至圖3中的步驟S4’藉以詳盡地說明光電轉換元件的 201007955 首先，如圖3及圖4A所示，步驟S1為提供一半導體 基板2，半導體基板2具有一表面211，且半導體基板2 由一 P型半導體層23及一 N型半導體層21所構成。 ^ 步驟S2為於半導體基板2的表面211形成至少一凹 結構211a及/或至少一凸結構2Ub，其結構如圖4B所示。 其t，在步驟S2中，形成此等凹結構211a及/或此等凸結 構211b的方法可為濕式蝕刻，舉例來說，於此所述的凹 結構21 la及7或凸結構21 可利用酸性蝕刻液以蝕刻半導 體基板2的表面211所形成。 如圖3及圖4C所示，步驟S3為提供複數半導體奈米 粒子25於表面211以作為遮罩，且以本實施例為例，此 些半導體奈米粒子25均勻地分散在半導體基板2的表面 211 〇 最後，步驟S4則是藉由步驟S3中所形成的半導體夺 米粒子25以對半導體基板2的表面2ιι進行蝕刻；亦即， 敍^半2體基板2的表面211並形成複數個微結構2Uc， 2庄,¾的是’在此步财所揭露的㈣製程是以乾式姓 說明，當然亦可依實際需要配合應用濕式儀刻 成複數個微結構211c。 均體基板2與半導體奈米粒子25的材料 勺為+導體材料，故在形成微結構2山後，更可藉由 此些半導體奈米粒子25的步驟，以使最終的 牛導體基板2結構可如圖4D所示。 其中’在步驟S3中形成半導體奈米粒子㈣方式可 11 201007955 為化學氣相沉積（CVD)、物理氣相沈積（PVD)、電漿增 強型化學式氣相沈積（PECVD)、蒸鍍系統、溶膠-凝膠 (sol-gel)法或其組合。而當步驟S4中蝕刻半導體基板2 的表面211的方式為乾式蝕刻時，其中的乾式蝕刻可為物 ： 理性蝕刻或化學性蝕刻，常見的方法則包含有電漿蝕刻， ' 當然亦可依實際需要配合應用濕式蝕刻以形成複數個微 結構211c，但不以此為限。 更詳細來說，上述的半導體奈米粒子25是由均勻分 ® 散的複數個半導體奈米粒子所構成，不過此些半導體粒子 25的排列方式並不限於規則的排列方式；換言之，其亦可 根據不同產品的設計與需求而呈現不規則的方式排列。另 外，值得一提的是，半導體奈米粒子25的材料可選自碳 化矽（SiC)、氮化石夕（SiN)、非晶石夕（amorphous-Si)之 一或其組合，然非用以限制本發明，半導體奈米粒子25 的材料亦可選用其他較硬之半導體奈米粒子及/或上述材 φ 料之組合。 此外，本發明所揭露的半導體奈米粒子25雖以保護 半導體基板2的表面211之作用為例說明，亦可依實際需 要對半導體基板2的表面211進行沈積（或其他製程）， 由於半導體奈米粒子25下方的區域並未沈積，因此在移 除半導體奈米粒子25後可使得微結構211c暴露出來。 綜上所述，因依據本發明之光電轉換元件及其製造方 法，其藉由半導體奈米粒子以提供奈米級的遮蔽效果，使 得在蝕刻半導體基板的表面時，可形成至少一奈米級的微 12 201007955 結構，與習知技術相較，本發明具有奈米級微結構的半導 體基板表面能夠有效地將光線導入至半導體基板内’而不 各易使光線發生反射的現象，因此可提升半導體基板對光 線的利用率。 另外’因為遮罩的材料亦為半導體材料，其製作過卷 與半導體元件之㈣過程时㈣性，㈣量產，成本伯 ，並且遮罩為寬能隙半導體，目此喊有部分的奈米丰 ❼在半導體基板内，亦不會降低半導體基料 以上所述僅為舉例性，而非 本發明之精神與範_，而對其進性者。任何未脫麟 應包含於後附之申請專利範圍中。效修改或變更，均 【圖式簡單說明】 圖1為一種習知半導體基板的結構示意圖； 圖2為依據本發明較佳實施例之 構示意圖； 種牛導體基板的結 ^ 3為圖2之光電轉換元件㈣造方㈣流程圖； 圖从至圖奶為圖3之光電轉換元件製 步驟示意圖。 乂方法的^私 【主要元件符號說明】 1 :太陽能基板 11、21 : N型半導體 13 201007955 111、211 :表面 llla、 211a :凹結構 lllb、 211b :凸結構 13、23 : P型半導體 2:半導體基板 211c :微結構 25 :半導體奈米粒子 S1〜S4 :製作流程[Technical Field] The present invention relates to a photoelectric conversion element, and more particularly to a photoelectric conversion element having a microstructure on its surface and a method of manufacturing the same. j [Prior Art] In order to enhance the solar cell's ability to absorb light, it is common to increase the surface area of the solar substrate by increasing the surface area of the solar substrate, or to increase the amount of light entering or into the solar substrate. An anti-reflection layer is deposited on the surface of the substrate to reduce the reflection of light by the solar substrate, thereby increasing the light entering the interior of the solar substrate. In addition, some of the techniques are surface treatment (e.g., roughening treatment) of the solar substrate, so that the unit area of the solar substrate can have a larger angle of the incident surface to reduce the reflectance of the solar substrate to light. For the surface treatment described above, it is conventionally realized by a chemical etching method, for example, a solar substrate of a single crystal rock by a wet-type method is used to coarsely round a single crystal stone: 〇n〇_Sl) surface. Among them, the commonly used surnames are potassium hydroxide (KQH) or oxyhydrogen (Na()H) and other test solvents, ^ wet _ after the single W domain energy substrate surface will be due to the ability of single crystal The pyramid shape is used to enhance the absorption of light = 'These techniques can't be used more than (10) (pGiy_si). The main reason is the money (4) process towel, the grain of the side liquid P _The speed is different, so the surface of the polycrystalline solar substrate 201007955 cannot be as sharp as the surface of the solar substrate of the single crystal germanium. Therefore, the surface treatment method of wet etching for a polycrystalline second solar substrate cannot effectively improve the light absorbing ability of the polycrystalline solar substrate. Referring to Fig. 1, in order to provide an effective surface treatment method for a polycrystalline silicon solar substrate, a conventional technique is to wet-etch the surface 111 of the polycrystalline solar substrate 1 with an acidic etching solution. Here, the polycrystalline silicon solar substrate 1 is exemplified by a common structure of a P-type semiconductor layer 13 and an N-type semiconductor layer 11, and the surface of the polycrystalline silicon solar substrate 1 is passed through using fluorinated acid (HF) as an etching liquid. After the wet etching, it has a shape of at least one concave structure 111a and/or a convex structure 111b, thereby achieving the effect of surface texturization. The acidic etching solution may be selected from the group consisting of nitric acid, sulfuric acid, phosphoric acid, acetic acid, and combinations thereof in addition to the above hydrofluoric acid. Further, in order to improve the uniformity of the concave structure 111a and/or the convex structure 111b on the surface of the polycrystalline solar substrate 1, φ must pass the polycrystalline solar substrate 1 through a plurality of wet-type etching processes. However, this will lead to problems such as increased process costs, reduced product yields, and increased process man-hours. However, the above wet etching method using an acidic etching solution can etch a concave structure and/or a convex structure on the surface of the polycrystalline silicon solar substrate, but the concave structure and/or the convex structure formed by wet etching are in size. Still not small enough, so that there are still a number of sections of a certain area in these structures. Therefore, when light is incident on the polycrystalline stone solar panel, some of the light will be reflected due to this cross section, resulting in a polycrystalline germanium solar base. The 201007955 board has poor light utilization. SUMMARY OF THE INVENTION An object of the present invention is to provide a photoelectric conversion element and a method for manufacturing the same that can reduce the reflectance of a photoelectric conversion element to improve the utilization ratio of the solar substrate and the light. SUMMARY OF THE INVENTION An object of the present invention is to provide a photoelectric conversion element and a method of manufacturing the same, wherein the photoelectric conversion element is particularly suitable for a polycrystalline silicon solar cell system. To achieve the above object, a photoelectric conversion element according to the present invention comprises a semiconductor substrate and a plurality of microstructures on the surface of the semiconductor substrate. The semiconductor substrate has a surface having at least a concave structure and/or at least one convex structure. Here, the microstructure is formed by forming a plurality of semiconductor-negative semiconductor particles on a surface as a mask and etching the surface. In order to achieve the above object, a method for fabricating a photoelectric conversion element according to the present invention comprises the steps of: providing a semiconductor substrate having a surface; forming at least one concave structure on the surface of the semiconductor substrate and/or a convex structure Providing a plurality of semiconductor nanoparticles on the surface as a mask; and etching the surface of the semiconductor substrate and forming a plurality of microstructures. - According to the above, the photoelectric conversion element and the method of manufacturing the same according to the present invention, by arranging the conductor nanoparticle to provide a nano-level shielding effect, can form at least when etching the surface of the semiconductor substrate Compared with the prior art, the semi-conducting 201007955 body substrate surface of the present invention having a nano-scale microstructure can have a lower light reflectance and improve the utilization of light by the semiconductor substrate. In addition, because the material of the mask is also a semiconductor material, the manufacturing process can be matched with the existing solar cell production technology, the mass production is easy, the cost is low, and the hydrogen atoms generated in the production process are related to the semiconductor substrate and the interface defect. There is a purification effect, and the photoelectric conversion efficiency is increased, and since the mask is a wide band gap semiconductor, the photoelectric conversion efficiency is not lowered even if it remains on the element. [Embodiment] Hereinafter, a photoelectric conversion element and a method of manufacturing the same according to a preferred embodiment of the present invention will be described with reference to the accompanying drawings, wherein the same elements will be described with the same reference numerals. Please refer to FIG. 2, which is a schematic structural view of a photoelectric conversion element according to a preferred embodiment of the present invention. The photoelectric conversion element includes a semiconductor substrate φ 2 and a plurality of microstructures 211c. The semiconductor substrate 2 has a surface 211 having at least one concave structure 211a and/or at least one convex structure 211b, and the microstructure 211c is located on the surface 211. Taking the embodiment as an example, the microstructures 211c are located further in the concave structures 211a and/or the convex structures 211b. Here, the microstructure 211c is formed by using a semiconductor nanoparticle (not shown) as a mask and etching the surface 211 of the semiconductor substrate 2. It is to be noted that the material of the above-mentioned semiconductor substrate 2 may be a single crystal stone, an amorphous stone, and a polycrystalline stone, and a combination thereof, a semiconductor material 201007955. However, the present invention is particularly applicable to a polycrystalline germanium semiconductor. A semiconductor substrate 2 made of a material. In more detail, the material of the semiconductor substrate 2 may be selected from the group consisting of a P-type semiconductor material, a ?-type semiconductor material, and combinations thereof. According to the embodiment shown in Fig. 2, the semiconductor substrate 2 is composed of a P-type semiconductor layer and an N-type semiconductor layer 21. In addition, the concave structure 211a and/or the convex structure 211b are formed by etching the surface 211 of the semiconductor substrate 2 by wet etching, and the concave structure 211a and/or the convex structure 2m are described. The microstructure phantom & is etched by the dry etching and/or wet etching process to etch the surface 211 of the semiconductor substrate 2, more specifically, at the top of the surface of the semiconductor substrate 2 when the microstructure 211c is formed. A plurality of semiconductor nanoparticles (not shown) are provided thereon by means of the semiconductor nanoparticles to mask the localized surface 211 regions and to etch the microstructures 2Uc thereon. On the application level, the above photoelectric conversion element can be applied to a solar battery. The above is a structure of a photoelectric conversion element disclosed in the present invention, and a method for manufacturing the above photoelectric conversion element is proposed. As shown in FIG. 3, the manufacturing method includes steps S1 to %. Meanwhile, in order to combine each step with its corresponding structure, please - and refer to FIG. 4A to FIG. 4D, wherein the structure of FIG. 4A corresponds to the step shown in FIG. 3 and the structure shown in FIG. 4B. Corresponding to the steps in FIG. 3, the structure of FIG. 4c= corresponds to the step in FIG. 3, and the structure shown in FIG. 4D to step S4' in FIG. 3 is used to explain in detail the 201007955 of the photoelectric conversion element. As shown in FIG. 3 and FIG. 4A, the step S1 is to provide a semiconductor substrate 2 having a surface 211, and the semiconductor substrate 2 is composed of a P-type semiconductor layer 23 and an N-type semiconductor layer 21. Step S2 is to form at least one concave structure 211a and/or at least one convex structure 2Ub on the surface 211 of the semiconductor substrate 2, and its structure is as shown in FIG. 4B. t, in step S2, the method of forming the concave structures 211a and/or the convex structures 211b may be wet etching. For example, the concave structures 21 la and 7 or the convex structures 21 may be An acidic etching solution is used to etch the surface 211 of the semiconductor substrate 2. As shown in FIG. 3 and FIG. 4C, step S3 is to provide a plurality of semiconductor nano-particles 25 on the surface 211 as a mask, and in the embodiment, the semiconductor nano-particles 25 are uniformly dispersed on the semiconductor substrate 2. Surface 211 〇 Finally, step S4 is to etch the surface 2 of the semiconductor substrate 2 by the semiconductor rice particles 25 formed in step S3; that is, to form the surface 211 of the half-body substrate 2 and form a plurality of The microstructure 2Uc, 2 Zhuang, 3⁄4 is 'the process disclosed in this step (4) The process is described by the dry name, and of course, it can be combined with the wet instrument to form a plurality of microstructures 211c according to actual needs. The material scoop of the homogeneous substrate 2 and the semiconductor nanoparticle 25 is a +conductor material, so after the formation of the microstructure 2, the steps of the semiconductor nanoparticle 25 can be used to make the final structure of the bovine conductor substrate 2. Can be as shown in Figure 4D. Wherein 'the formation of semiconductor nanoparticles in step S3 (4) mode 11 201007955 for chemical vapor deposition (CVD), physical vapor deposition (PVD), plasma enhanced chemical vapor deposition (PECVD), evaporation system, sol a sol-gel method or a combination thereof. When the surface 211 of the semiconductor substrate 2 is etched in the step S4 by dry etching, the dry etching may be: rational etching or chemical etching, and the common method includes plasma etching, 'of course, depending on the actual It is necessary to apply wet etching to form a plurality of microstructures 211c, but not limited thereto. More specifically, the semiconductor nanoparticle 25 described above is composed of a plurality of semiconductor nanoparticles dispersed uniformly, but the arrangement of the semiconductor particles 25 is not limited to a regular arrangement; in other words, Arranged in an irregular manner according to the design and needs of different products. In addition, it is worth mentioning that the material of the semiconductor nanoparticle 25 may be selected from one of cerium carbide (SiC), cerium nitride (SiN), amorphous-Si or a combination thereof, but is not used. To limit the present invention, the material of the semiconductor nanoparticle 25 may be selected from other hard semiconductor nanoparticles and/or a combination of the above materials. In addition, the semiconductor nanoparticle 25 disclosed in the present invention is described as an example of protecting the surface 211 of the semiconductor substrate 2, and the surface 211 of the semiconductor substrate 2 may be deposited (or other processes) according to actual needs. The area under the rice particles 25 is not deposited, so that the microstructure 211c can be exposed after the removal of the semiconductor nanoparticles 25. In summary, according to the photoelectric conversion element and the method of manufacturing the same according to the present invention, the semiconductor nanoparticle is provided to provide a nano-level shielding effect, so that at least one nanometer level can be formed when etching the surface of the semiconductor substrate. The micro 12 201007955 structure, compared with the prior art, the surface of the semiconductor substrate having the nano-scale microstructure can effectively introduce light into the semiconductor substrate without any phenomenon that light is easily reflected, thereby improving The utilization of light by a semiconductor substrate. In addition, because the material of the mask is also a semiconductor material, the process of making the coil and the semiconductor component (4) is (4), (4) mass production, cost, and the mask is a wide-gap semiconductor, so as to call a part of the nanometer. In the semiconductor substrate, the semiconductor substrate is not reduced. The above description is merely exemplary, and not the spirit and scope of the present invention. Any unremoved lining should be included in the scope of the patent application attached. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic view showing the structure of a conventional semiconductor substrate; FIG. 2 is a schematic view showing a structure according to a preferred embodiment of the present invention; Conversion element (4) Maker (4) Flow chart; Figure from the figure to the figure is a schematic diagram of the steps of the photoelectric conversion element of Figure 3. Description of the method of the 乂 method [Main component symbol description] 1 : Solar substrate 11, 21: N-type semiconductor 13 201007955 111, 211: Surface llla, 211a: concave structure 111b, 211b: convex structure 13, 23: P-type semiconductor 2: Semiconductor substrate 211c: microstructure 25: semiconductor nanoparticle S1 to S4: production flow