TW201333281A - Crystalline silicon ingot including nucleation promotion particles and method of fabricating the same - Google Patents
Crystalline silicon ingot including nucleation promotion particles and method of fabricating the same Download PDFInfo
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本發明關於一種矽晶鑄錠(crystalline silicon ingot)及其製造方法，並且特別地，關於利用成核促進顆粒(nucleation promotion particle)讓其底部為小尺寸矽晶粒且整體缺陷密度低之矽晶鑄錠及其製造方法。The present invention relates to a crystalline silicon ingot and a method of manufacturing the same, and, in particular, to a twin crystal using a nucleation promoting particle such that the bottom thereof is a small-sized germanium crystal grain and has a low overall defect density. Ingot and its manufacturing method.
大多的太陽能電池是吸收太陽光，進而產生光伏效應(photovoltaic effect)。目前太陽能電池的材料大部份都是以矽材為主，主要是因矽材為目前地球上最容易取到的第二多元素，並且其具有材料成本低廉、沒有毒性、穩定性高等優點，並且其在半導體的應用上已有深厚的基礎。Most solar cells absorb sunlight and produce a photovoltaic effect. At present, most of the materials of solar cells are mainly coffins, mainly because coffins are the second most easily available elements on the earth, and they have the advantages of low material cost, no toxicity, and high stability. And it has a solid foundation in the application of semiconductors.
以矽材為主的太陽能電池有單晶矽、多晶矽以及非晶矽三大類。以多晶矽做為太陽能電池的原材，主要是基於成本的考量，因為相較於以現有的拉晶法(Czochralski method,CZ method)以及浮動區域法(floating zone method,FZ method)所製造的單晶矽，多晶矽價格相對地便宜許多。The solar cells based on coffins include three types: single crystal germanium, polycrystalline germanium and amorphous germanium. The use of polycrystalline germanium as a raw material for solar cells is mainly based on cost considerations because it is compared to the conventional CZ method and the floating zone method (FZ method). Crystal germanium, polycrystalline germanium prices are relatively cheaper.
使用在製造太陽能電池上的多晶矽，傳統上是利用一般鑄造製程來生產。利用鑄造製程來製備多晶矽，進而應用在太陽能電池上是本技術領域的現有技術。簡言之，將高純度的矽熔融在模內(例如，石英坩堝)成矽融湯(silicon melt)，在控制凝固下冷卻矽融湯以形成多晶矽鑄錠。接著，該多晶矽鑄錠被切割成接近太陽能電池尺寸大小的晶圓，進而應用在製造太陽能電池上。以這種方法製造的多晶矽鑄錠為矽結晶晶粒的聚集體，其中在由其製成的晶圓中，晶粒相互之間的晶向實際上是隨機的。The use of polycrystalline germanium in the manufacture of solar cells has traditionally been produced using conventional casting processes. The use of a casting process to prepare polycrystalline germanium, which is then applied to solar cells, is prior art in the art. Briefly, high purity germanium is melted in a mold (e.g., quartz crucible) into a silicon melt, and the melted soup is cooled under controlled solidification to form a polycrystalline germanium ingot. Next, the polycrystalline germanium ingot is cut into wafers close to the size of the solar cell and used in the manufacture of solar cells. The polycrystalline tantalum ingot produced in this way is an aggregate of ruthenium crystal grains in which crystal orientations of crystal grains with each other are actually random.
在依傳統鑄造製程所製造的多晶矽中，因為晶粒的隨機晶向而難以對所製成的晶片表面進行粗紋化。表面粗紋化後可降低光反射並提高通過電池表面的光能吸收，來提高光伏電池的效率。另外，在現有的多晶矽晶粒之間的晶界中形成的"扭折"，傾向形成成核差排的簇集、或形成多條線差排形式的結構缺陷。這些差排以及它們趨向吸引的雜質，造成了由現有的多晶矽製成的光伏電池中電荷載子的快速復合。這會導致電池的效率降低。由這類多晶矽製成的光電池通常比由單晶矽製成的等效光伏電池的效率低，即使考慮了在由現有技術製造的單晶矽中所存在之缺陷的徑向分佈。然而，因為製造現有的多晶矽相對簡單且成本更低，以及在電池加工中有效的缺陷鈍化，多晶矽成了廣泛用於製造光伏電池之矽材料的形式。In the polycrystalline silicon produced by the conventional casting process, it is difficult to roughen the surface of the wafer to be formed because of the random crystal orientation of the crystal grains. The roughening of the surface can reduce the light reflection and increase the absorption of light energy through the surface of the battery to improve the efficiency of the photovoltaic cell. Further, the "kneading" formed in the grain boundaries between the existing polycrystalline germanium grains tends to form clusters of nucleation difference rows or structural defects in the form of a plurality of line difference rows. These rows and the impurities they tend to attract cause a rapid recombination of charge carriers in photovoltaic cells made from existing polycrystalline germanium. This can result in a decrease in the efficiency of the battery. Photovoltaic cells made from such polycrystalline germanium are generally less efficient than equivalent photovoltaic cells made from single crystal germanium, even considering the radial distribution of defects present in single crystal germanium fabricated by the prior art. However, since the fabrication of existing polysilicon is relatively simple and less costly, as well as defect passivation that is effective in battery processing, polysilicon has become a widely used form of tantalum material for the fabrication of photovoltaic cells.
現有技術揭露利用單晶矽晶種層並基於方向性凝固製成矽晶鑄錠，且一般是利用大尺寸且晶向為(100)的單晶矽立方體作為主要晶種。其期望用於矽單晶太陽能電池製造矽晶圓的晶向為(100)方向，因為利用刻蝕方法方便地形成光捕獲表面(light-trapping surface)。不幸的是，在(100)晶向的晶粒與隨機成核的晶粒競爭的結晶期間(100)晶向的晶粒表現差。為了最大化在鑄錠中引晶的結晶體積，現有技術揭示利用(111)晶向的矽的邊界包圍(100)晶向的矽晶種面積。該邊界非常成功地抑制了其他晶向的晶體。以這種方法，能夠鑄造具有高性能的單晶矽及/或雙晶(bi-crystal)矽塊狀體的鑄錠，其最大化所得的晶圓的少數載流子之壽命，該晶圓用於製造高效太陽能電池。在此，術語"單晶矽"是指單晶矽的主體，其在整個範圍內具有一個一致的晶體晶向。術語"雙晶矽"是指如下的矽的主體，其在大於或等於該主體體積50%的範圍內具有一個一致的晶體晶向，且在主體的剩餘體積內具有另一個一致的晶體晶向。例如，這種雙晶矽可以包含具有一個晶體晶向的單晶矽主體，其緊鄰構成結晶矽剩餘體積的另一種具有不同晶體晶向的單晶矽主體。此外，現有的多晶矽是指具有厘米規模的細微性分佈的結晶矽，且在矽的主體內具有多種隨機晶向的晶體。然而，前述現有技術是利用昂貴單晶矽晶種的方法，大幅增加矽晶鑄錠整體的製造成本。The prior art discloses the use of a single crystal twin seed layer and a twin crystal ingot based on directional solidification, and generally uses a single crystal germanium cube having a large size and a crystal orientation of (100) as a main seed crystal. It is desirable to use a germanium single crystal solar cell to fabricate a germanium wafer with a crystal orientation of (100) direction because a light-trapping surface is conveniently formed by an etching method. Unfortunately, grains in the (100) crystal orientation during crystallization during the (100) crystal orientation of the grains compete with randomly nucleated grains. In order to maximize the crystal volume of seeding in the ingot, the prior art discloses that the area of the seed crystal of the (100) crystal orientation is surrounded by the boundary of the (111) crystal orientation. This boundary is very successful in suppressing crystals in other crystal orientations. In this way, an ingot having a high performance single crystal germanium and/or a bi-crystal germanium block can be cast, which maximizes the lifetime of minority carriers of the resulting wafer. Used to manufacture high efficiency solar cells. Here, the term "single crystal germanium" means a main body of a single crystal germanium having a uniform crystal crystal orientation over the entire range. The term "bimorph" refers to a body of ruthenium having a uniform crystal orientation in a range of greater than or equal to 50% of the volume of the body, and having another uniform crystal orientation within the remaining volume of the body. . For example, such a twin germanium may comprise a single crystal germanium body having a crystal crystal orientation, which is adjacent to another single crystal germanium body having a different crystal crystal orientation in the immediate vicinity of the remaining volume of the crystalline germanium. Further, the prior art polycrystalline germanium refers to a crystal enthalpy having a fine distribution of a centimeter scale, and having a plurality of crystals having a random crystal orientation in the main body of the crucible. However, the aforementioned prior art is a method of utilizing an expensive single crystal twin seed crystal, which greatly increases the manufacturing cost of the entire twin crystal ingot.
另一現有技術則不借助昂貴的單晶矽晶種，其利用局部過冷(undercooling)先在坩堝底部佈滿橫向長晶，再向上成長柱狀結構，其大尺寸矽晶粒具有低缺陷密度。因此，根據其他現有技術製造的矽晶鑄錠，其經切片後之矽晶圓製成太陽能電池，可以獲得較高的光電轉換效率。Another prior art does not rely on expensive single crystal twins, which utilizes local undercooling to first fill the lateral growth of the crucible at the bottom of the crucible, and then grow up the columnar structure, the large size of the crucible has a low defect density. . Therefore, according to other prior art tantalum ingots, the sliced silicon wafer is made into a solar cell, and high photoelectric conversion efficiency can be obtained.
然而，利用局部過冷的現有技術所提技術僅在實驗室裡成功驗證。延伸至工業級尺寸時，多晶矽鑄造欲以局部過冷控制晶面樹枝狀晶成長佈滿於坩堝底部變得較為困難。工業等級多晶矽鑄造受到坩堝與整體受熱均勻性的影響，增加初始過冷度的控制變異，容易令多晶矽在坩堝底部成長為大晶粒且成為缺陷密度偏高的區域，在成長延伸時更快速增加缺陷密度，致使矽晶鑄錠整體晶體品質變差，後續製成的太陽能電池的光電轉換效率也較低。However, the techniques proposed in the prior art using local supercooling have only been successfully verified in the laboratory. When extended to industrial grades, polycrystalline tantalum casting is difficult to control the crystal lattice dendritic growth to fill the bottom of the crucible with local subcooling. Industrial grade polycrystalline tantalum casting is affected by the uniformity of enthalpy and overall heat, and the variation of initial supercooling is controlled. It is easy for polycrystalline germanium to grow into large grains at the bottom of the crucible and become a region with high defect density, which increases more rapidly during growth and extension. The defect density causes the overall crystal quality of the twinned ingot to deteriorate, and the photoelectric conversion efficiency of the subsequently produced solar cell is also low.
因此，本發明所欲解決的技術問題在於提供一種利用成核促進顆粒協助矽晶粒成核，且成長成底部為小尺寸矽晶粒、整體缺陷密度低之矽晶鑄錠及其製造方法。本發明之矽晶鑄錠後續製成的太陽能電池的成本較低、光電轉換效率也較高。Therefore, the technical problem to be solved by the present invention is to provide a twin-crystalline ingot which utilizes nucleation-promoting particles to assist in nucleation of ruthenium grains, and which grows into a small-sized ruthenium crystal at the bottom, and has a low overall defect density, and a method for producing the same. The solar cell produced by the twin crystal ingot of the present invention has a lower cost and a higher photoelectric conversion efficiency.
本發明之一較佳具體實施例之製造一矽晶鑄錠之方法，首先係鋪設多個成核促進顆粒在一模內之底部。模本身定義一垂直方向。每一個成核促進顆粒係由一主顆粒以及由接合在主顆粒的表面上之多個次顆粒所構成。多個次顆粒之平均粒徑係小於多個主顆粒之平均粒徑。接著，該方法係安裝一矽原料至模內，且放置在多個成核促進顆粒上。接著，該方法係加熱模，直至矽原料全部熔化成矽熔湯。接著，該方法係控制關於矽熔湯之至少一熱場參數(thermal control parameter)，致使從矽熔湯中多個矽晶粒在多個成核促進顆粒上成核且沿垂直方向成長。最後，該方法係繼續控制至少一熱場參數，讓多個矽晶粒繼續沿垂直方向成長，且直至矽熔湯全部凝固以獲得矽晶鑄錠。In a preferred embodiment of the invention, a method of making a twine ingot is first to lay a plurality of nucleation promoting particles at the bottom of a mold. The mold itself defines a vertical direction. Each of the nucleation promoting particles is composed of a primary particle and a plurality of secondary particles bonded to the surface of the primary particle. The average particle diameter of the plurality of secondary particles is smaller than the average particle diameter of the plurality of primary particles. Next, the method installs a stack of raw materials into the mold and is placed on a plurality of nucleation promoting particles. Next, the method is to heat the mold until the crucible material is completely melted into a crucible soup. Next, the method controls at least one thermal control parameter regarding the bismuth melt, such that a plurality of ruthenium grains from the bismuth melt are nucleated on the plurality of nucleation promoting particles and grow in the vertical direction. Finally, the method continues to control at least one thermal field parameter such that the plurality of tantalum grains continue to grow in the vertical direction until the tantalum melt is fully solidified to obtain a twinned ingot.
於一具體實施例中，每一主顆粒可以由石墨、矽、氧化鋁、碳化矽、氮化矽、氮化鋁或其他熔點高於約1400℃之材料所形成。In one embodiment, each of the primary particles may be formed of graphite, tantalum, alumina, tantalum carbide, tantalum nitride, aluminum nitride, or other materials having a melting point above about 1400 °C.
於一具體實施例中，每一次顆粒可以由石墨、矽、氧化鋁、碳化矽、氮化矽、氮化鋁或其他熔點高於約1400℃之材料所形成。In one embodiment, each particle may be formed from graphite, tantalum, alumina, tantalum carbide, tantalum nitride, aluminum nitride, or other materials having a melting point above about 1400 °C.
於一具體實施例中，多個主顆粒之平均粒徑係大於約1mm。In one embodiment, the plurality of primary particles have an average particle size of greater than about 1 mm.
於一具體實施例中，多個次顆粒之平均粒徑係小於約1μm。In one embodiment, the plurality of secondary particles have an average particle size of less than about 1 [mu]m.
本發明之矽晶鑄錠包含沿本身之一垂直方向成長的多個矽晶粒以及位在其底部之多個成核促進顆粒。每一成核促進顆粒係由一主顆粒以及由接合在主顆粒的表面上之多個次顆粒所構成。多個次顆粒之平均粒徑係小於多個主顆粒之平均粒徑。The twinned ingot of the present invention comprises a plurality of germanium grains grown in a vertical direction of one of itself and a plurality of nucleation promoting particles positioned at the bottom thereof. Each nucleation promoting particle consists of a primary particle and a plurality of secondary particles bonded to the surface of the primary particle. The average particle diameter of the plurality of secondary particles is smaller than the average particle diameter of the plurality of primary particles.
與先前技術不同，無須借助昂貴的單晶矽晶種，也無須執行難達成的局部過冷度以致在坩堝底部成核矽晶粒，本發明反而利用成本較低的成核促進顆粒直接提供矽熔湯密集的成核點，製造高密度的晶粒分布，來抑制成長快速的晶向生成，進而達到大量降低大尺寸矽晶粒分佈比例。由於，小尺寸矽晶粒型態於長晶過程中有較少晶粒競爭現象，且小尺寸矽晶粒分佈緊密較易趨於單一向上成長，減少晶粒大吃小情形與避免柱狀晶無法成長完整的情況。此外，伴隨得來的高比例晶界在長晶過程中，能以應力場吸引缺陷集中或於晶界上滑移釋放熱應力，抑制差排等缺陷快速增加，因此獲得高品質的矽晶鑄錠，後續製成的太陽能電池的光電轉換效率也較高。Different from the prior art, the invention does not need to rely on expensive single crystal twins, and does not need to perform the difficult local subcooling to nucleate the germanium grains at the bottom of the crucible, and the present invention uses the lower cost nucleation promoting particles to directly provide the crucible. The dense nucleation point of the melt is used to produce a high-density grain distribution to suppress the rapid growth of crystal orientation, thereby achieving a large reduction in the proportion of large-size tantalum crystals. Because the small-sized 矽-grain pattern has less grain competition in the process of crystal growth, and the small-sized 矽 crystal grain distribution tends to tend to grow upwards in a single direction, reducing the grain size and avoiding the columnar crystal. Unable to grow a complete situation. In addition, the accompanying high-ratio grain boundary can attract the defect concentration or the sliding on the grain boundary to release the thermal stress in the process of crystal growth, and suppress the rapid increase of defects such as poor row, thereby obtaining high-quality twin crystal casting. Ingots, the solar cell produced subsequently has a higher photoelectric conversion efficiency.
關於本發明之優點與精神可以藉由以下的發明詳述及所附圖式得到進一步的瞭解。The advantages and spirit of the present invention will be further understood from the following detailed description of the invention.
請參閱第1A圖至第1D圖，係以截面視圖示意地繪示本發明之一較佳具體實施例之製造一矽晶鑄錠的方法。Referring to FIGS. 1A through 1D, a method of manufacturing a twin ingot in a preferred embodiment of the present invention is schematically illustrated in a cross-sectional view.
如第1A圖所示，本發明之製造方法大致上依循定向凝固系統(directional solidification system,DSS)，採用一DSS長晶爐1。DSS長晶爐1之構造包含一爐體10、由一上絕熱罩122與一下絕熱板124構成之一絕熱籠12、安置在絕熱籠12內之一定向凝固塊18、支撐定向凝固塊18之至少一支撐柱19、安置在定向凝固塊18上之一基座17、安置在基座17內之一模16、安置在模之上之一加熱器14以及貫通爐體10與絕熱籠12之一惰性氣體導管11。As shown in Fig. 1A, the manufacturing method of the present invention substantially follows a directional solidification system (DSS) using a DSS crystal growth furnace 1. The structure of the DSS crystal growth furnace 1 comprises a furnace body 10, an insulating cage 12 formed by an upper heat insulating cover 122 and a lower heat insulating plate 124, a directional solidification block 18 disposed in the heat insulating cage 12, and a supporting directional solidification block 18 At least one support post 19, a base 17 disposed on the directional solidification block 18, a mold 16 disposed in the base 17, a heater 14 disposed above the mold, and the furnace body 10 and the insulating cage 12 An inert gas conduit 11.
實務上，模16可以是石英坩堝。定向凝固塊18可以由石墨製成。基座17可以由石墨製成。惰性氣體導管11用以導入氬氣至絕熱籠12內。In practice, the mold 16 can be a quartz crucible. The directional solidification block 18 can be made of graphite. The susceptor 17 can be made of graphite. The inert gas conduit 11 is used to introduce argon into the adiabatic cage 12.
如第1A圖所示，本發明之方法首先係鋪設多個成核促進顆粒2至模16內之底部。模16本身定義一垂直方向V。多個成核促進顆粒2已鋪滿模16內之底部者為佳，多個成核促進顆粒2鋪設的層數未有限制。As shown in Fig. 1A, the method of the present invention first lays a plurality of nucleation promoting particles 2 to the bottom of the mold 16. The modulo 16 itself defines a vertical direction V. It is preferred that a plurality of nucleation promoting particles 2 have been laid over the bottom of the mold 16, and the number of layers of the plurality of nucleation promoting particles 2 is not limited.
請參閱第2圖，係成核促進顆粒2的結構示意圖。特別地，每一個成核促進顆粒2係由一主顆粒22以及由接合在主顆粒22的表面上之多個次顆粒24所構成。並且，多個次顆粒24之平均粒徑係小於多個主顆粒22之平均粒徑。Please refer to FIG. 2, which is a schematic diagram of the structure of the nucleation promoting particles 2. Specifically, each of the nucleation promoting particles 2 is composed of a primary particle 22 and a plurality of secondary particles 24 bonded to the surface of the primary particle 22. Further, the average particle diameter of the plurality of secondary particles 24 is smaller than the average particle diameter of the plurality of primary particles 22.
接著，本發明之方法係安裝一矽原料30至模16內，且放置在多個成核促進顆粒2上。裝入多個成核促進顆粒2以及矽原料30的模16則放置基座17裡，如第1A圖所示。Next, the method of the present invention installs a raw material 30 into the mold 16 and is placed on a plurality of nucleation promoting particles 2. A mold 16 in which a plurality of nucleation promoting particles 2 and a crucible raw material 30 are loaded is placed in the susceptor 17, as shown in Fig. 1A.
接著，本發明之方法係加熱模16，直至矽原料30全部熔化成矽熔湯32，如第1B圖所示。Next, the method of the present invention heats the mold 16 until the crucible material 30 is completely melted into the crucible soup 32 as shown in Fig. 1B.
接著，本發明之方法係控制關於矽熔湯32之至少一熱場參數，致使從矽熔湯32中多個矽晶粒34在多個成核促進顆粒2上成核且沿該垂直方向V成長，如第1C圖所示。至少一熱場參數包含一熱傳輸通量。如第1C圖所示，DSS長晶爐1在長晶過程中，上絕熱罩122緩慢上升，使原本受該絕熱籠12籠罩之密閉空間產生間隙，此間隙便成為絕熱籠12內、外部熱交換的管道，產生熱傳輸通量。Next, the method of the present invention controls at least one thermal field parameter for the crucible soup 32 such that a plurality of niobium grains 34 from the crucible soup 32 nucleate on the plurality of nucleation promoting particles 2 and along the vertical direction V Grow, as shown in Figure 1C. At least one thermal field parameter includes a heat transfer flux. As shown in Fig. 1C, in the process of crystal growth of the DSS crystal growth furnace 1, the upper heat insulating cover 122 is slowly raised, so that a gap is formed in the sealed space which is originally covered by the heat insulating cage 12, and the gap becomes heat inside and outside the heat insulating cage 12. The exchanged pipes produce heat transfer flux.
最後，本發明之方法係繼續控制至少一熱場參數，讓多個矽晶粒34繼續沿垂直方向V成長，且直至矽熔湯32全部凝固以獲得矽晶鑄錠3，如第1D圖所示。Finally, the method of the present invention continues to control at least one thermal field parameter, allowing a plurality of germanium grains 34 to continue to grow in the vertical direction V , and until the crucible melt 32 is fully solidified to obtain a twinned ingot 3, as shown in FIG. Show.
於一具體實施例中，每一主顆粒22可以由石墨、矽、氧化鋁、碳化矽、氮化矽、氮化鋁或其他熔點高於約1400℃之材料所形成。In one embodiment, each of the primary particles 22 may be formed of graphite, tantalum, alumina, tantalum carbide, tantalum nitride, aluminum nitride, or other materials having a melting point above about 1400 °C.
於一具體實施例中，每一次顆粒24可以由石墨、矽、氧化鋁、碳化矽、氮化矽、氮化鋁或其他熔點高於約1400℃之材料所形成。In one embodiment, each of the particles 24 may be formed of graphite, tantalum, alumina, tantalum carbide, tantalum nitride, aluminum nitride, or other materials having a melting point above about 1400 °C.
於一具體實施例中，多個主顆粒22之平均粒徑係大於約1mm。In one embodiment, the plurality of primary particles 22 have an average particle size of greater than about 1 mm.
於一具體實施例中，多個次顆粒24之平均粒徑係小於約1μm。In one embodiment, the plurality of secondary particles 24 have an average particle size of less than about 1 [mu]m.
於一具體實施例中，多個成核促進顆粒2並且抑制多個矽晶粒34於成長過程中缺陷密度的增加。矽晶鑄錠距矽晶鑄錠內缺陷密度沿著垂直方向V之增率範圍為0.01%/mm~10%/mm。矽晶鑄錠內缺陷密度之增率係藉由下列公式計算：In one embodiment, the plurality of nucleation promotes the particles 2 and inhibits the increase in defect density of the plurality of germanium grains 34 during growth. The growth rate of the defect density in the twin crystal ingot from the vertical direction V is 0.01%/mm~10%/mm. The increase in defect density in a twinned ingot is calculated by the following formula:
(Dx2-Dx1)/(x2-x1)；其中X2、X1分別為矽晶鑄錠沿垂直方向V不同高度處，Dx2、Dx1分別為矽晶鑄錠在X2、X1處切面之缺陷密度。 (D x2 -D x1) / ( x2-x1); wherein X2, X1 respectively V silicon ingot at different heights in the vertical direction, D x2, D x1 are silicon ingot X2, X1 of the section Defect density.
小尺寸矽晶粒也可以有效抑制缺陷密度的增率。本發明之矽晶鑄錠其中央底部成長小尺寸矽晶粒(<10mm)的機率較高，其側邊或角落底部可能只有局部成長小尺寸矽晶粒(<10mm)。本發明之矽晶鑄錠垂直垂直方向V之切面，其小尺寸矽晶粒所佔面積比例會影響晶粒成長幅度以及缺陷密度的增率。Small size germanium grains can also effectively suppress the increase in defect density. The twin crystal ingot of the present invention has a high probability of growing small-sized germanium grains (<10 mm) at the center bottom, and the side or corner bottom may have only locally grown small-sized germanium grains (<10 mm). Silicon ingot of the present invention cut perpendicular to the vertical direction V, a ratio of the area occupied by the small size of the silicon particles affects the rate of grain growth and the growth rate defect density.
於一具體實施例中，成核促進顆粒2的製備係先調製含有次顆粒24的漿料，含有次顆粒24的漿料塗佈在主顆粒22的表面，再將塗佈漿料的主顆粒22置於高溫爐中至少將水分烘乾，及製成成核促進顆粒2。高溫爐的溫度可以維持在1000~1100℃。次顆粒24可以藉由化學共價鍵接合在主顆粒22的表面上。高溫爐的溫度可以更高，讓次顆粒24與主顆粒22的表面部分燒結或完全燒結在一起。In one embodiment, the nucleation promoting particles 2 are prepared by first preparing a slurry containing the secondary particles 24, and the slurry containing the secondary particles 24 is coated on the surface of the primary particles 22, and then the primary particles of the coating slurry are applied. 22 is placed in a high temperature furnace to at least dry the moisture, and to form nucleation promoting particles 2. The temperature of the high temperature furnace can be maintained at 1000~1100 °C. The secondary particles 24 may be bonded to the surface of the primary particles 22 by chemical covalent bonds. The temperature of the high temperature furnace can be higher, allowing the secondary particles 24 to be sintered or completely sintered with the surface portion of the primary particles 22.
利用矽晶種的先前技術，在矽原料全部熔化成矽熔湯的過程中，必須控制熱場參數讓矽晶種部分熔化，但不能全部熔化。因此，先前技術在熱場參數的控制上較為複雜、困難。本發明利用成核促進顆粒之技術，僅須讓矽原料全部熔化成矽熔湯，無控制矽晶種部分融化的問題須解決，因此，本發明之方法在熱場參數控制上較先前技術來得簡單、容易。With the prior art of strontium seed crystals, in the process of melting all of the bismuth raw materials into bismuth melt, it is necessary to control the thermal field parameters to partially melt the strontium seeds, but not all of them. Therefore, the prior art is complicated and difficult in controlling the parameters of the thermal field. The invention utilizes the technology of nucleation-promoting granules, and only needs to melt all the strontium raw materials into bismuth melted soup, and the problem of uncontrolled crystallization of the strontium seeds must be solved. Therefore, the method of the present invention is superior to the prior art in controlling the thermal field parameters. Simple and easy.
請再次參閱第1A圖至第1D圖，加熱器14係安置在模16之上。定向凝固塊18係安置在模16之下方，間接與模16接觸。至少一熱場參數可以包含從加熱器14至模16之一第一溫度梯度、從矽熔湯20之底部至定向凝固塊18之頂部之一第二溫度梯度或一熱傳輸通量等等熱場參數。於實務上，第一溫度梯度需控制在低於0.4℃/cm，可以藉由加大加熱器14與模16之間的距離，或將加熱器14的加熱溫度控制在低於1410℃，等方法來達成。第二溫度梯度需控制在高於17℃/cm，可以藉由加大定向凝固塊18的厚度，等方法來達成。熱傳輸通量需控制在高於37000W/m2，可以藉由將上絕熱罩122開速提升至3cm/hr以上來達成。Referring again to FIGS. 1A through 1D, the heater 14 is placed over the mold 16. The directional solidification block 18 is placed below the mold 16 in indirect contact with the mold 16. The at least one thermal field parameter may include a first temperature gradient from the heater 14 to the die 16, a second temperature gradient from the bottom of the crucible soup 20 to the top of the directional solidification block 18, or a heat transfer flux, etc. Field parameters. In practice, the first temperature gradient needs to be controlled below 0.4 ° C / cm, by increasing the distance between the heater 14 and the mold 16, or by controlling the heating temperature of the heater 14 below 1410 ° C, etc. The method is to achieve. The second temperature gradient needs to be controlled above 17 ° C / cm, which can be achieved by increasing the thickness of the directional solidification block 18, and the like. The heat transfer flux needs to be controlled to be higher than 37,000 W/m 2 , which can be achieved by raising the opening speed of the upper heat insulating cover 122 to 3 cm/hr or more.
請參閱第3圖，係顯示本發明之矽晶鑄錠3的結構示意圖。本發明之矽晶鑄錠3包含沿本身之一垂直方向成長V的多個矽晶粒34以及位在其底部之多個成核促進顆粒2。如第2圖所示，每一成核促進顆粒2係由一主顆粒22以及由接合在主顆粒22的表面上之多個次顆粒24所構成。並且，矽晶鑄錠3緊鄰多個成核促進顆粒2的矽晶粒34之平均晶粒尺寸小於約10mm。進一步，矽晶鑄錠3內缺陷密度沿著垂直方向之增率範圍為0.01%/mm~10%/mm。Referring to Fig. 3, there is shown a schematic structural view of the twinned ingot 3 of the present invention. The twinned ingot 3 of the present invention comprises a plurality of tantalum grains 34 which grow V in one of their perpendicular directions and a plurality of nucleation promoting particles 2 which are located at the bottom thereof. As shown in Fig. 2, each of the nucleation promoting particles 2 is composed of a primary particle 22 and a plurality of secondary particles 24 bonded to the surface of the primary particle 22. Also, the average grain size of the germanium grains 34 of the twinned ingot 3 adjacent to the plurality of nucleation promoting particles 2 is less than about 10 mm. Further, the increase rate of the defect density in the twin crystal ingot 3 in the vertical direction ranges from 0.01%/mm to 10%/mm.
構成成核促進顆粒2之主顆粒22及次顆粒24的材料、尺寸已詳述於上文，在此不再贅述。The materials and dimensions of the primary particles 22 and the secondary particles 24 constituting the nucleation promoting particles 2 have been described in detail above and will not be described herein.
請參閱第4圖，A鑄錠為本發明之一矽晶鑄錠，其沿著矽晶鑄錠高度之平均晶粒尺寸變化係標示於第4圖中。於第4圖中並且標示B鑄錠其沿著矽晶鑄錠高度變化之平均晶粒尺寸，做為對照。B鑄錠係根據現有技術所提出的方法所製造的矽晶鑄錠。Referring to Figure 4, the A ingot is a twined ingot of the present invention, and the average grain size change along the height of the twin ingot is indicated in Figure 4. In Figure 4 and the average grain size of the B ingot along the height of the twine ingot is indicated as a control. B ingot is a twinned ingot manufactured according to the method proposed in the prior art.
請參閱第5圖，A鑄錠的角落區域、側壁區域以及中央區域沿著矽晶鑄錠高度變化之缺陷密度係標示於第5圖中。第5圖中的缺陷密度係以缺陷面積比例表示。做為對照，B鑄錠的角落區域、側壁區域以及中央區域沿著矽晶鑄錠高度而變化之缺陷面積比例也標示於第5圖中。Referring to Figure 5, the defect density of the corner region, the sidewall region, and the central region of the A ingot along the height of the twine ingot is shown in Figure 5. The defect density in Fig. 5 is expressed in terms of the defect area ratio. As a comparison, the ratio of the defect area of the corner region, the side wall region, and the central region of the B ingot along the height of the twine ingot is also shown in FIG.
請參閱第6圖，取材於A鑄錠的底部區域、中間區域以及頂部區域(距離A鑄錠底部約250mm)所製成太陽能電池的光電轉換效率係標示於第6圖中。做為對照，取材於B鑄錠的底部區域、中間區域以及頂部區域(距離B鑄錠底部約250mm)所製成太陽能電池的光電轉換效率也標示於第6圖中。取材於A鑄錠所製成太陽能電池的平均光電轉換效率高過取材於B鑄錠所製成太陽能電池的平均光電轉換效率約0.24%。取材於B鑄錠各區域所製成太陽能電池的光電轉換效率為16.8%。取材於A鑄錠各區域所製成太陽能電池的光電轉換效率範圍為16.96%~17.11%，相較下，各區域所製成太陽能電池的光電轉換效率相當接近，利於電池製造商應用於電池的製造，更具商業應用價值。Referring to Figure 6, the photoelectric conversion efficiency of the solar cell fabricated from the bottom region, the middle region, and the top region of the A ingot (about 250 mm from the bottom of the A ingot) is shown in Fig. 6. As a comparison, the photoelectric conversion efficiency of the solar cell fabricated from the bottom region, the middle region, and the top region of the B ingot (about 250 mm from the bottom of the B ingot) is also shown in Fig. 6. The average photoelectric conversion efficiency of the solar cell fabricated from the A ingot is higher than the average photoelectric conversion efficiency of the solar cell fabricated from the B ingot by about 0.24%. The photoelectric conversion efficiency of the solar cell produced from each region of the B ingot was 16.8%. The photoelectric conversion efficiency of solar cells made from various regions of A ingot ranges from 16.96% to 17.11%. Compared with the solar cells, the photoelectric conversion efficiency of solar cells made in each region is quite close, which is beneficial to battery manufacturers in battery applications. Manufacturing, more commercial application value.
從第4圖、第5圖及第6圖之數據，可以清楚瞭解B鑄錠的長晶過程在坩堝底成長為大晶粒且成為缺陷密度較低的區域，但在成長延伸時更快速增加缺陷密度，致使矽晶鑄錠整體晶體品質變差，其後續製成的太陽能電池的光電轉換效率較低。相較於B鑄錠，A鑄錠的長晶利用引入成核促進層直接提供矽熔湯密集的成核點，來大量降低大尺寸矽晶粒分佈比例。由於，小尺寸矽晶粒型態於長晶過程中有較少晶粒競爭現象，且小尺寸矽晶粒分佈緊密較易趨於單一向上成長，減少晶粒大吃小情形與避免柱狀晶無法成長完整。此外，A鑄錠中分佈密度高的晶界在長晶過程中，能以應力場吸引缺陷集中或於晶界上滑移釋放熱應力，抑制差排等缺陷快速增加，進而讓矽晶鑄錠整體有較佳的晶體品質，後續製成的太陽能電池的光電轉換效率也較高。From the data in Fig. 4, Fig. 5 and Fig. 6, it can be clearly seen that the growth process of B ingot grows into large grains at the bottom of the crucible and becomes a region with low defect density, but increases more rapidly during growth and extension. The defect density causes the overall crystal quality of the twinned ingot to deteriorate, and the photoelectric conversion efficiency of the subsequently produced solar cell is low. Compared with the B ingot, the long crystal of the A ingot uses the nucleation promoting layer to directly provide the nucleation point of the bismuth melting furnace, so as to greatly reduce the proportion of the large size 矽 crystal. Because the small-sized 矽-grain pattern has less grain competition in the process of crystal growth, and the small-sized 矽 crystal grain distribution tends to tend to grow upwards in a single direction, reducing the grain size and avoiding the columnar crystal. Can't grow to be complete. In addition, the grain boundary with high distribution density in the A ingot can attract the defects in the stress field or slip on the grain boundary to release the thermal stress, and suppress the rapid increase of defects such as poor row, and then let the twin ingots The overall crystal quality is better, and the photoelectric conversion efficiency of the subsequently produced solar cell is also higher.
藉由以上較佳具體實施例之詳述，係希望能更加清楚描述本發明之特徵與精神，而並非以上述所揭露的較佳具體實施例來對本發明之面向加以限制。相反地，其目的是希望能涵蓋各種改變及具相等性的安排於本發明所欲申請之專利範圍的面向內。因此，本發明所申請之專利範圍的面向應該根據上述的說明作最寬廣的解釋，以致使其涵蓋所有可能的改變以及具相等性的安排。The features and spirit of the present invention are intended to be more apparent from the detailed description of the preferred embodiments. On the contrary, the intention is to cover various modifications and equivalents that are within the scope of the invention as claimed. Therefore, the scope of the patent application of the present invention should be construed broadly in the light of the above description, so that it covers all possible changes and arrangements.
1．．．DSS長晶爐1. . . DSS crystal furnace
10．．．爐體10. . . Furnace body
11．．．惰性氣體導管11. . . Inert gas conduit
12．．．絕熱籠12. . . Insulation cage
122．．．上絕熱罩122. . . Upper heat shield
124．．．下絕熱板124. . . Lower insulation board
14．．．加熱器14. . . Heater
16．．．模16. . . mold
17．．．基座17. . . Pedestal
18．．．定向凝固塊18. . . Directional solidification block
19．．．支撐柱19. . . Support column
2．．．成核促進顆粒2. . . Nucleation promoting particles
22．．．主顆粒twenty two. . . Primary particle
24．．．次顆粒twenty four. . . Secondary particle
3．．．矽晶鑄錠3. . . Twin crystal ingot
30．．．矽原料30. . .矽 raw materials
32．．．矽熔湯32. . . Melting soup
34．．．矽晶粒34. . .矽 grain
V．．．垂直方向 V. . . Vertical direction
第1A圖至第1D圖係以截面視圖示意地繪示本發明之製造一矽晶鑄錠的方法之一較佳具體實施例。1A to 1D are schematic cross-sectional views showing a preferred embodiment of the method of manufacturing a twinned ingot of the present invention.
第2圖係本發明之成核促進顆粒的結構示意圖。Figure 2 is a schematic view showing the structure of the nucleation promoting particles of the present invention.
第3圖係本發明之矽晶鑄的結構示意圖。Figure 3 is a schematic view showing the structure of the twin crystal casting of the present invention.
第4圖係本發明之一較佳具體實施例所製造的矽晶鑄錠與其對照的矽晶鑄錠之矽晶粒尺寸比較結果。Figure 4 is a graph showing the comparison of the grain size of the tantalum ingots produced by a preferred embodiment of the present invention with the twin crystal ingots of the control.
第5圖係本發明之一較佳具體實施例所製造的矽晶鑄錠與其對照的矽晶鑄錠之缺陷密度比較結果。Figure 5 is a graph showing the comparison of defect densities of twinned ingots produced by a preferred embodiment of the present invention and their control twinned ingots.
第6圖係本發明之一較佳具體實施例所製造的矽晶鑄錠與其對照的矽晶鑄錠之後續製成太陽能電池的平均光電轉換效率比較結果。Figure 6 is a graph showing the results of comparison of the average photoelectric conversion efficiency of a solar cell produced by a twinned ingot of a preferred embodiment of the present invention and a controlled twin ingot.
1．．．DSS長晶爐1. . . DSS crystal furnace
10．．．爐體10. . . Furnace body
11．．．惰性氣體導管11. . . Inert gas conduit
12．．．絕熱籠12. . . Insulation cage
122．．．上絕熱罩122. . . Upper heat shield
124．．．下絕熱板124. . . Lower insulation board
14．．．加熱器14. . . Heater
16．．．模16. . . mold
17．．．基座17. . . Pedestal
18．．．定向凝固塊18. . . Directional solidification block
19．．．支撐柱19. . . Support column
2．．．成核促進顆粒2. . . Nucleation promoting particles
32．．．矽熔湯32. . . Melting soup
34．．．矽晶粒34. . .矽 grain
V．．．垂直方向 V. . . Vertical direction
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|---|---|---|---|---|
| TWI593837B (en) * | 2014-11-12 | 2017-08-01 | 中美矽晶製品股份有限公司 | Method of producing an ingot |
Families Citing this family (9)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN104152987A (en) * | 2014-07-22 | 2014-11-19 | 山西中电科新能源技术有限公司 | Polycrystalline silicon seeding device and method |
| CN104152990A (en) * | 2014-09-10 | 2014-11-19 | 山西中电科新能源技术有限公司 | Polycrystalline-silicon high-efficiency silicon ingot seeding particle and preparation method thereof |
| CN104152989A (en) * | 2014-09-10 | 2014-11-19 | 山西中电科新能源技术有限公司 | Polycrystalline-silicon high-efficiency silicon ingot seeding plate and preparation method thereof |
| CN104152988A (en) * | 2014-09-10 | 2014-11-19 | 山西中电科新能源技术有限公司 | Polycrystalline-silicon high-efficiency silicon ingot seeding device and seeding method thereof |
| CN104630884B (en) * | 2015-01-23 | 2017-06-23 | 东海晶澳太阳能科技有限公司 | A kind of fine melt efficient polycrystalline silicon ingot casting seed crystal and its preparation method and application |
| DE102015201988A1 (en) * | 2015-02-05 | 2016-08-11 | Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V. | Process for the production of multicrystalline silicon |
| CN104862778A (en) * | 2015-06-16 | 2015-08-26 | 江苏协鑫硅材料科技发展有限公司 | Preparation method of polycrystalline silicon ingot, polycrystalline silicon ingot and polycrystalline silicon wafer |
| CN105088337A (en) * | 2015-07-27 | 2015-11-25 | 奥特斯维能源（太仓）有限公司 | Polysilicon seeding method |
| CN108486652A (en) * | 2018-04-19 | 2018-09-04 | 常熟华融太阳能新型材料有限公司 | A kind of high-efficiency seed crystal layer reducing polycrystalline silicon ingot casting dislocation |
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| JP4054873B2 (en) * | 2003-07-17 | 2008-03-05 | 国立大学法人東北大学 | Method for producing Si-based crystal |
| TWI534307B (en) * | 2010-06-15 | 2016-05-21 | 中美矽晶製品股份有限公司 | Method of manufacturing crystalline silicon ingot |
| CN101935868A (en) * | 2010-09-17 | 2011-01-05 | 浙江大学 | Crucible for growing large-grain cast polycrystalline silicon |
| CN102094239A (en) * | 2010-09-28 | 2011-06-15 | 常州天合光能有限公司 | Ingot polycrystalline furnace bottom crucible protective plate |
| CN101979718A (en) * | 2010-11-30 | 2011-02-23 | 奥特斯维能源（太仓）有限公司 | Quartz crucible and method for casting quasi-single crystal |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| TWI593837B (en) * | 2014-11-12 | 2017-08-01 | 中美矽晶製品股份有限公司 | Method of producing an ingot |
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| CN103255475A (en) | 2013-08-21 |
| TWI620838B (en) | 2018-04-11 |
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