201247535 六、發明說明： 【發明所屬之技術領域】 本發明關於純化矽之方法，其中在坩堝中製備矽熔體 ’於該坩堝中建立溫度梯度，該矽熔體產生定向凝固且在 該定向凝固期間該矽熔體中的至少某些區域保持運動。本 發明亦關於用於進行該方法的裝置。 【先前技術】 高純度矽主要用於製造積體電路。然而亦發現高純度 矽在太陽能電池之製造中的應用漸增。太陽能等級矽之純 度必須爲至少9 9 · 9 9 %。因此，原材料之製造最重要。在 地函中可取得之可用矽通常呈矽石形式（二氧化矽、石英 砂），可大量獲得矽石以作爲起始材料。 從矽石（Si02)製造高純度矽之方法爲碳熱還原。其 中，使用碳來將起始材料石英砂中的氧與矽分離。於矽之 碳熱還原期間’亦存在純石英砂中的雜質（主要爲鋁、鐵 及鈣）’除了氣態一氧化矽（CO )之外，亦形成碳化矽（ SiC)且溶解之碳亦殘留在該矽熔體中。碳與SiC殘留在 該矽中作爲主要雜質。爲獲得充分純度之太陽能等級矽， 因此在碳熱還原之後必須從該矽移除該碳。 於該矽熔體冷卻期間，碳主要是以S i C之小粒子形式 沉澱。該等粒子與矽晶格結合不良，且該等粒子於液態矽 中之溶解性遠優於與矽晶體的結合。因此，在一種純化矽 之方法中’對矽熔體進行非常緩慢之定向凝固。該矽熔體 -5- 201247535 變得富含碳及Sic。因此首先凝固之定向凝固矽的區域之 純度特別高，然而最後凝固之矽熔體含有明顯更多之雜質 ，此係因爲該矽凝固期間該矽熔體中之碳及Sic粒子的濃 度持續提高之故。降低矽熔體中之Sic濃度的方法從 Norwegian University of Science and Technology 之 Anne-Karin S0iland 的論文"Silicon for Solar Cells" ( 2004 年 10 月，IMT-report 2004:65 )中得知。然而，其中提到的氧 化具有同時形成一氧化矽（SiO )的缺點。 由於結晶前緣之雜質提高，且在該熱力過程中藉由熱 擴散從結晶前緣去除雜質非常費時，因此藉由定向凝固純 化矽之前提係該矽熔體凝固得非常緩慢。定向凝固之矽的 重度污染部分被除去的越多，如此特別是使得首先凝固之 區域成爲較高純度之矽源。 缺點在於該方法非常費時。因此DE 38 02 531 A1提 出一種用於純化矽之方法，其中在凝固期間該矽熔體中的 至少某些區域保持運動。 由於矽熔體之運動的緣故，除了熱擴散之外，亦藉由 該矽熔體的機械性驅動對流而從該結晶前緣移除干擾粒子 及雜質。因此，可某種程度提高相對於碳之結晶速率。 然而，亦需要進一步提高結晶速率及進一步改善矽之 純度。因此，仍存在長製程時間及所形成之純化方法成本 高昂的缺點。亦存在高能量消耗及所形成之成本的缺點。 【發明內容】201247535 VI. Description of the Invention: [Technical Field] The present invention relates to a method for purifying a crucible in which a crucible melt is prepared in a crucible to establish a temperature gradient in the crucible, the crucible melt producing directional solidification and solidification in the orientation At least some of the area of the crucible melt remains in motion during this period. The invention also relates to apparatus for carrying out the method. [Prior Art] High purity germanium is mainly used to manufacture integrated circuits. However, it has also been found that the use of high purity germanium in the manufacture of solar cells is increasing. The solar grade must have a purity of at least 9 9 · 9 9 %. Therefore, the manufacture of raw materials is of the utmost importance. The available yttrium available in the earth's letter is usually in the form of vermiculite (cerium oxide, quartz sand), and a large amount of vermiculite can be obtained as a starting material. The method for producing high-purity lanthanum from vermiculite (SiO 2 ) is carbothermal reduction. Among them, carbon is used to separate oxygen in the starting material quartz sand from ruthenium. During the carbothermal reduction of Yuxi, there are also impurities (mainly aluminum, iron and calcium) in pure quartz sand. In addition to gaseous ruthenium oxide (CO), lanthanum carbide (SiC) is formed and the dissolved carbon remains. In the crucible melt. Carbon and SiC remain in the crucible as the main impurity. In order to obtain a solar grade of sufficient purity, the carbon must be removed from the crucible after the carbothermal reduction. During the cooling of the crucible melt, the carbon is mainly precipitated as small particles of S i C. These particles are poorly bonded to the germanium lattice, and the solubility of the particles in liquid helium is much better than that of helium crystals. Therefore, in a method of purifying rhodium, the crucible melt is subjected to very slow directional solidification. The bismuth melt -5 - 201247535 becomes rich in carbon and Sic. Therefore, the purity of the solidified directional solidified zone is particularly high, but the final solidified melt contains significantly more impurities because the concentration of carbon and Sic particles in the tantalum melt continues to increase during solidification of the crucible. Therefore. A method for lowering the Sic concentration in the bismuth melt is known from Anne-Karin S0iland, "Silicon for Solar Cells" (IMT-report 2004: 65, October 2004) by Norwegian University of Science and Technology. However, the oxidation mentioned therein has the disadvantage of simultaneously forming cerium oxide (SiO). Since the impurity of the crystallization front is increased, and the removal of impurities from the crystallization front by thermal diffusion during the thermal process is very time consuming, the enthalpy melt solidifies very slowly before the enthalpy is purified by directional solidification. The more the heavily contaminated portion of the directional solidification is removed, the more so that the first solidified zone becomes the source of higher purity. The disadvantage is that the method is very time consuming. Thus, DE 38 02 531 A1 proposes a method for purifying a crucible in which at least some of the crucible melt remains in motion during solidification. Due to the movement of the ruthenium melt, in addition to thermal diffusion, interfering particles and impurities are removed from the crystallization front by mechanically driving convection of the ruthenium melt. Therefore, the crystallization rate with respect to carbon can be increased to some extent. However, it is also necessary to further increase the crystallization rate and further improve the purity of the ruthenium. Therefore, there are still disadvantages of a long process time and a high cost of the resulting purification process. There are also disadvantages of high energy consumption and the cost of formation. [Summary of the Invention]
-6- 201247535 因此，待藉由本發明解決該問題以克服先前技術之缺 點。特別是，應提出簡單且具成本效益之方法，藉由該方 法改善定向凝固之矽的純度。亦應儘可能減少除碳或s i C 以外之雜質。此外，該方法應儘可能具有成本效益地進行 ，及當用於大量製造時應安定。 待藉由本發明解決之問題係以將純化氣體至少偶爾通 過該矽熔體及某些區域來解決。 爲此，可設想在該矽熔體中建立基本上垂直之溫度梯 度，以使該矽至少偶爾具有基本上水平之結晶前緣凝固， 較佳係與水平坩堝底部平行。根據本發明，藉由避免結晶 前緣中之凹陷，由於機械性驅動之矽熔體不需要在結晶前 緣中洗出小凹穴，故移除矽熔體中之雜質得以簡化。 亦可設想結晶前緣彎曲，其中在中間之凝固的部分比 在坩堝邊緣之凝固的部分更厚。因此，單晶成功地在該坩 堝中間生長。在較少單晶區域之情況下，該材料中存在較 少晶界。由於雜質優先累積在晶界上，故此較少晶界對於 材料之純度而言較佳。 亦可設想在第一步驟中，先將矽通過過濾器，然後在 坩堝中建立溫度梯度，矽熔體以該溫度梯度進行定向凝固 〇 此外’根據本發明，可設想該矽熔體或該用於矽熔體 之矽係由矽石之碳熱還原製得。由於藉由該方法可特別有 效地減少碳粒子及SiC粒子，故以此種方式獲得之矽熔體 特別適於該方法。 201247535 另外可設想在還原後立刻純化矽熔體。以此種方式可 能避免再熔融該矽。如此可節省用於再熔融所需要的能量 〇 根據本發明方法另一具體實例，可設想純化氣體包含 介於40與100體積％之間，較佳係介於60與95體積％之 間的原生氣體，其中使用惰性氣體，較佳爲氬、氮、氫或 其混合物作爲原生氣體。該等氣體特別適於純化矽。該原 生氣體之氣體及/或氣體混合物之類型可針對雜質類型而 調整。 根據本發明特別有利之方法的特徵在於該純化氣體係 以細微氣泡形式通過該矽熔體。細微氣泡相對於矽熔體具 有較大表面，因此改善純化效果》 此外，可設想在常壓及10 cm熔體深度下，該等氣泡 的平均半徑在〇.1至2 mm之範圍。 由於高溫及中等壓力條件，該純化氣體實際上表現得 如同理想氣體。氣泡半徑取決於由該矽熔體上方的氣體壓 力Pg所構成的壓力（常壓約100 N/m2 )、該矽熔體的液 體靜壓Ph (液態矽之密度p爲253 3 kg/m3時的液體靜壓 ，其爲矽熔體之高度h的線性函數）、及從該矽熔體對於 特定純化氣體之表面張力的小作用p〇 (但可忽視）。氣泡 之體積取決於液體的溫度，其大致對應於矽之熔點（約 1 6 82 °K )。根據理想氣體定律，在指定壓力下，氣泡之體 積及因而該氣泡半徑係藉由物質之量（分子之數量）所決 定》氣泡中之壓力取決於該氣泡上方之矽熔體高度，及取 -8- 201247535 決於該矽熔體上方之氣體壓力與矽熔體對於純化氣體之界 面能量。-6- 201247535 Therefore, the problem is to be solved by the present invention to overcome the disadvantages of the prior art. In particular, a simple and cost-effective method should be proposed by which the purity of the directional solidification crucible is improved. Impurities other than carbon or s i C should also be minimized. In addition, the method should be carried out as cost-effectively as possible and should be stabilized when used in large quantities. The problem to be solved by the present invention is to solve the problem of at least occasional passage of the purified gas through the crucible melt and certain areas. To this end, it is contemplated to establish a substantially vertical temperature gradient in the crucible melt such that the crucible at least occasionally has a substantially horizontal crystalline front solidification, preferably parallel to the horizontal crucible bottom. According to the present invention, by avoiding the depression in the crystallization front, since the mechanically driven ruthenium melt does not need to wash out the small pockets in the crystallization front, the removal of impurities in the ruthenium melt is simplified. It is also conceivable that the crystallization front edge is curved, wherein the solidified portion in the middle is thicker than the solidified portion at the rim edge. Therefore, the single crystal is successfully grown in the middle of the crucible. In the case of fewer single crystal regions, there are fewer grain boundaries in the material. Since the impurities preferentially accumulate on the grain boundaries, the less grain boundaries are preferred for the purity of the material. It is also conceivable in the first step that the crucible is passed through the filter and then a temperature gradient is established in the crucible, and the crucible melt is directionally solidified with the temperature gradient. Further, according to the invention, the crucible melt or the use is conceivable. The lanthanum of the yttrium melt is obtained by carbothermal reduction of vermiculite. Since the carbon particles and SiC particles can be particularly effectively reduced by this method, the niobium melt obtained in this manner is particularly suitable for the method. 201247535 It is also conceivable to purify the ruthenium melt immediately after reduction. In this way it is possible to avoid remelting the crucible. This saves the energy required for remelting. According to another embodiment of the method according to the invention, it is conceivable that the purification gas comprises between 40 and 100% by volume, preferably between 60 and 95% by volume. A gas in which an inert gas, preferably argon, nitrogen, hydrogen or a mixture thereof is used as the primary gas. These gases are particularly suitable for the purification of hydrazine. The type of gas and/or gas mixture of the primary gas can be adjusted for the type of impurity. A method which is particularly advantageous according to the invention is characterized in that the purified gas system passes through the crucible melt in the form of fine bubbles. The fine bubbles have a large surface with respect to the ruthenium melt, thus improving the purification effect. Furthermore, it is conceivable that the average radius of the bubbles is in the range of 〇1 to 2 mm at normal pressure and a melt depth of 10 cm. Due to the high temperature and moderate pressure conditions, the purified gas actually behaves as an ideal gas. The bubble radius depends on the pressure (normal pressure of about 100 N/m2) formed by the gas pressure Pg above the crucible melt, and the hydrostatic pressure Ph of the crucible melt (the density p of the liquid crucible is 253 3 kg/m3) The hydrostatic pressure, which is a linear function of the height h of the crucible melt, and the small effect p但 (but negligible) from the surface tension of the crucible melt for a particular purified gas. The volume of the bubble depends on the temperature of the liquid, which corresponds approximately to the melting point of the crucible (about 1 6 82 °K). According to the ideal gas law, at a given pressure, the volume of the bubble and thus the radius of the bubble is determined by the amount of the substance (the number of molecules). The pressure in the bubble depends on the height of the enthalpy above the bubble, and - 8- 201247535 Depends on the gas pressure above the helium melt and the interfacial energy of the helium melt for the purified gas.
3·η·Λ·Τ 4»π*ρ 其中 p ^ 100^+ p-gmh 重力加速度爲3·η·Λ·Τ 4»π*ρ where p ^ 100^+ p-gmh Gravity acceleration is
9 = 9,81 P9 = 9,81 P
I 通用氣體常數爲 及物質之量爲η。 因此在10 cm溶體深度之氣泡半徑r約爲％米。就1 〇 cm熔體深度之倍數X，吾人獲得氣泡半徑r約爲τ ~ Λ^米 〇 本發明之方法的特徵亦可爲該純化氣體以每1 0 cm坩 堝直徑介於0.1與20 Ι/min之體積流率通過該矽熔體。 另外可設想以1至600轉/分鐘，較佳爲30至200轉/ 分鐘之角速度攪拌該矽溶體，且因此保持運動。 亦可設想該結晶前緣區域中的矽熔體之運動基本上與 該結晶前緣平行。應確使整體結晶前緣基本上均勻肅清， 如此獲致均勻純度作用。 -9 - 201247535 根據本發明亦可設想該矽熔體具有溫度梯度，且最高 溫度爲2000°C。 根據本發明另一具體實例，可設想藉由攪拌器及/或 藉由交流電磁場使該矽熔體維持運動。藉由這兩種驅動類 型，可達成尤其適用之矽熔體的循環，因此獲致適當之純 化作用。 可進一步設想該矽熔體的定向凝固係藉由從交流電磁 場拉出該坩堝而引起，其中該矽熔體之結晶速率及/或結 晶前緣的形式係藉由降低該坩堝的速度及/或控制或調整 該交流電磁場之功率來控制及/或調整。藉由調整用於加 熱該矽熔體及用於攪拌該矽熔體二者的交流電磁場之功率 ，以及從該交流電磁場拉出坩堝之速率，可建立基本上水 平之結晶前緣且可獲致均勻之結晶速率。 亦可設想藉由純化氣體使矽熔體保持移動。此可提供 矽熔體之尤其徹底混合。 亦可設想將該矽熔體倒入該坩渦及/或於該坩堝中熔 融。 爲獲致額外純化效果，根據本發明可設想該矽熔體係 經過濾。過濾提供額外純化作用。此可能一部分由SiC粒 子表面上吸附外來物質，然後將該等物質沈積在該過濾器 表面上所造成。較佳變化係在該矽熔體表面區域（即，在 矽熔體/氣體界面）中使用該過濾器，及/或將該過濾器拉 過該矽熔體》可簡單地從該矽熔體過濾出SiC及碳粒子， 但亦可過濾出因以沖洗氣體處理而在該矽熔體中浮出之氮 -10- 201247535 化矽（S i N粒子），將之撇除或甚至傾析。 可設想用於過濾該矽熔體之多孔陶瓷及/或燒結玻料 ’較佳包含si〇2及/或氧化銷，尤佳爲經si〇2塗覆之陶瓷 ’其中從該矽熔體過濾出雜質。ZrO過濾器特別具有熱安 定性’且經常用於冶金。因此’其可容易且價廉地製得。 Si〇2塗層或Si〇2過濾器的優點係不會將額外污染導入該 矽熔體。 另外可設想經由孔徑介於1 〇 μηι與2 0 m m之間，較佳 係於0.1 mm與5 mm之間的多孔陶瓷及/或燒結玻料來過 濾該矽熔體。 亦可設想該矽熔體的至少某些區域被吸入該過濾器中 。此可容易提供對主要存在於表面上之雜質進行過濾。 亦可設想根據本發明，該純化氣體至少局部地經由過 濾器及/或燒結玻料導至該矽熔體。以此種方式獲致該純 化氣體之氣泡的更細微分布。此外，相同過濾器或相同燒 結玻料亦可用於過濾該矽熔體。 另外可設想使用氧、氮、氫、H20或鹵素氣體，較佳 爲氯氣，或該等氣體之混合物作爲純化氣體。亦可包含該 等氣體作爲二次氣體，其濃度爲該純化氣體的60至低於1 體積％。 此外，可設想根據本發明，將該純化氣體導入該結晶 前緣之區域，較佳在該結晶前緣上方1 cm至5 cm。藉由 正好在該結晶前緣之前緣提供氣體進料，獲致特別良好地 分離矽熔體之干擾雜質。 -11 - 201247535 本發明之方法特徵亦可在於該純化氣體係經由至少一 個攪拌器導至該矽熔體，藉由該攪拌器使該矽熔體保持運 動。可設想該攪拌器包含混合葉片用於驅動該循環。由於 氣體係以該攪拌器混合，可排除一種可能污染源。 可設想該至少一個攪拌器係由純化氣體之流驅動。二 者方法均意謂著減少導至該矽熔體之裝置數。由於每一裝 置亦爲潛在雜質來源，故減少導入之組件數對於結晶矽之 純度具有有益的效果。 當設想冷卻至少一個用於將純化氣體導入至該矽熔體 的氣體進料管線及/或至少一個攪拌器，特別是藉由純化 氣體冷卻，較佳係冷卻至低於矽之熔點的溫度，尤佳係介 於1 3 0 0 °c與1 4 1 0 °C之間，最佳係介於1 3 8 01：與1 4 1 0 °c之 間時，獲得本發明尤其有利之具體實例。由於該冷卻，在 氣體進料管線及/或一或多個攪拌器上形成薄矽層。因此 ，防止或至少減少該等組件之材料溶解。此外，該等組件 之表面因此方法而鈍化，因此不存在該等組件造成之污染 。該方法亦使得可能使用通常原本不可用之材料。例如， 可能使用經矽塗覆之熱安定金屬，諸如銥或鎢（彼等另外 亦具抗氧化性）。然後此可用於製造用於矽熔體中之相關 組件。然而，亦可能使用石英玻璃。 此種冷卻另外具有藉由從上方中心導入之攪拌器來加 強由矽熔體中之冷卻所產生之熱對流的優點。該方法亦促 進粒子（例如S i C及S i N )之形成。 待藉由本發明解決之問題亦藉由以此種方法純化矽的 -12- 201247535 裝置來解決’該裝置包含至少一個可加熱增渦，其中至少 —個氣體進料管線配置在該坩堝內部。 可設想該氣體進料管線包含至少一個過濾器及/或至 少一個燒結玻料’該過濾器或該燒結玻料的孔徑爲1 〇 μη1 至 1 mm 〇 另外可設想至少一個連接或可連接至高頻產生器的感 應線圈係配置在該坩堝周圍，該坩堝可以該線圈軸之方向 移出該感應場。 亦可設想將至少一個可旋轉攪拌器配置在該坩堝中。 可藉由該可旋轉攪拌器使該矽熔體循環。 根據本發明之裝置的特徵亦可爲該氣體進料管線係與 至少一個攪拌器整合。爲此，該氣體進料管線可以可旋轉 方式安裝。 此外，根據本發明可設想將至少一個混合葉片配置在 突出至該矽熔體之該氣體進料管線前端上。 亦可設想該氣體進料管線及/或該攪拌器基本上係由 Si02、SiC、鎢、碳化鎢及/或銥所構成，較佳包含矽塗層 ，或由矽所構成。 此外，根據本發明亦可提出包含用於降低該坩堝的降 低裝置，且包含用於控制或調整降低速度、該感應線圈之 功率、該至少一個氣體進料管線之冷卻、至少一個攪拌器 之冷卻及/或用於控制或調整該純化氣體之氣體流動的控 制系統之裝置。 最後，可設想該裝置包含大量絕緣層，較佳包含石墨 -13- 201247535 布、空氣、石墨、超高溫絕緣材料及/或絕緣粉末，尤佳 爲碳黑床。 一種具有額外的製程步驟來純化矽之完整方法及用於 進行本發明方法之本發明裝置的其他設備係描述於WO 201 0 03 7 694 A2，該案係以引用之方式倂入本申請案中。 本發明係根據導入純化氣體可能促進粒子形成，然後 由於定向凝固，收集可分離之經凝固之矽區域中的該等粒 子之意外發現爲基礎。若移除該部分，可獲致矽之純化。 此外，因該純化氣體之成核作用而形成的一些粒子亦因其 密度較低而浮至該矽熔體的表面，該處離結晶前緣特別遠 ，因此不會與該凝固中之矽相結合。 若從該矽熔體過濾出於該矽熔體中所形成的外來物質 之粒子，則產生特殊結合效果。意外發現多孔陶瓷（其可 經Si〇2塗覆）可用於此。該等過濾器可簡單地浸入該矽 熔體中，或將部分矽熔體吸入或通過該等過濾器。該過濾 器必須加熱至矽呈液態的溫度，以防止該等過濾器迅速阻 塞。或者，例如通過此種過濾器，亦可簡單地傾倒出外來 物質之粒子，使得可將經過濾之矽送回該矽熔體中。 可將該純化氣體經由至少一個管注入該矽熔體中。該 純化氣體可同時用於冷卻該管。該管亦可配置在攪拌器中 或在坩堝之壁中。由於冷卻，可在該管上產生一層矽，或 可安定化已存在之矽層。該管當然亦可藉由其他方法來冷 卻。 相同種類之邊界層意謂著可防止矽熔體中存在可能從I The general gas constant and the amount of matter are η. Therefore, the bubble radius r at a solution depth of 10 cm is about % meter. For a multiple X of the melt depth of 1 〇cm, we obtain a bubble radius r of about τ ~ Λ ^ m. The method of the present invention may also be characterized in that the purified gas has a diameter of 0.1 and 20 每 per 1 cm. The volumetric flow rate of min passes through the helium melt. It is also conceivable to stir the ruthenium solution at an angular velocity of from 1 to 600 rpm, preferably from 30 to 200 rpm, and thus keep moving. It is also contemplated that the motion of the ruthenium melt in the region of the crystallization front is substantially parallel to the crystallization front. It should be ensured that the overall crystallization front is substantially uniformly cleared, thus achieving uniform purity. -9 - 201247535 It is also contemplated in accordance with the present invention that the bismuth melt has a temperature gradient and a maximum temperature of 2000 °C. According to another embodiment of the invention, it is contemplated that the crucible melt is maintained in motion by an agitator and/or by an alternating electromagnetic field. With these two drive types, a particularly suitable circulation of the helium melt can be achieved, thus achieving proper purification. It is further contemplated that the directional solidification of the tantalum melt is caused by pulling the crucible from an alternating electromagnetic field, wherein the rate of crystallization of the tantalum melt and/or the form of the crystalline front is reduced by the speed of the crucible and/or Control or adjust the power of the alternating electromagnetic field to control and/or adjust. By adjusting the power of the alternating electromagnetic field for heating the tantalum melt and for agitating the tantalum melt, and the rate at which the crucible is pulled from the alternating electromagnetic field, a substantially horizontal crystal leading edge can be established and uniform Crystallization rate. It is also conceivable to keep the crucible melt moving by the purification gas. This provides a particularly thorough mixing of the bismuth melt. It is also conceivable to pour the crucible melt into the crucible and/or melt it in the crucible. In order to obtain additional purification effects, it is contemplated in accordance with the present invention that the ruthenium system is filtered. Filtration provides additional purification. This may be caused in part by the adsorption of foreign matter on the surface of the SiC particles, which is then deposited on the surface of the filter. Preferably, the filter is used in the surface area of the crucible melt (i.e., in the crucible melt/gas interface) and/or the filter is drawn through the crucible melt. The SiC and carbon particles are filtered out, but the nitrogen -10- 201247535 bismuth (S i N particles) which is floated in the ruthenium melt by treatment with a flushing gas can be filtered out, or even decanted. It is conceivable that the porous ceramic and/or sintered glass for filtering the tantalum melt 'preferably comprises si〇2 and/or an oxidation pin, particularly preferably a ceramic coated with si〇2, wherein the melt is filtered from the crucible Impurities. ZrO filters are particularly thermally stable' and are often used in metallurgy. Therefore, it can be easily and inexpensively produced. The advantage of the Si〇2 coating or Si〇2 filter is that no additional contamination is introduced into the crucible melt. It is also conceivable to filter the ruthenium melt through a porous ceramic and/or sintered glass having an aperture between 1 〇 μηι and 20 mm, preferably between 0.1 mm and 5 mm. It is also contemplated that at least some areas of the crucible melt are drawn into the filter. This makes it easy to provide filtration of impurities mainly present on the surface. It is also conceivable according to the invention that the purified gas is at least partially guided to the crucible melt via a filter and/or sintered glass. In this way, a finer distribution of the bubbles of the purified gas is obtained. In addition, the same filter or the same sintered glass can also be used to filter the crucible melt. It is also conceivable to use oxygen, nitrogen, hydrogen, H20 or a halogen gas, preferably chlorine gas, or a mixture of such gases as a purification gas. These gases may also be included as secondary gases at a concentration of from 60 to less than 1% by volume of the purified gas. Furthermore, it is contemplated that in accordance with the present invention, the purified gas is introduced into the region of the crystallization front, preferably from 1 cm to 5 cm above the crystallization front. By providing a gas feed just at the leading edge of the crystallization front, interference impurities which are particularly well separated from the ruthenium melt are obtained. -11 - 201247535 The method of the present invention may also be characterized in that the purified gas system is conducted to the crucible melt via at least one agitator, by which the crucible melt is kept moving. It is contemplated that the agitator includes mixing blades for driving the cycle. Since the gas system is mixed with the agitator, a possible source of contamination can be eliminated. It is contemplated that the at least one agitator is driven by a stream of purified gas. Both methods mean reducing the number of devices leading to the melt. Since each device is also a source of potential impurities, reducing the number of components introduced has a beneficial effect on the purity of the crystalline ruthenium. When it is envisaged to cool at least one gas feed line for introducing the purified gas to the helium melt and/or at least one agitator, in particular by cooling with a purified gas, preferably cooled to a temperature below the melting point of the crucible, A particularly advantageous embodiment of the invention is obtained when the system is between 1 300 ° C and 1 4 1 0 ° C, and the optimum is between 1 3 8 01: and 1 4 1 0 °c. . Due to this cooling, a thin layer of tantalum is formed on the gas feed line and/or one or more agitators. Thus, material dissolution of the components is prevented or at least reduced. Moreover, the surfaces of the components are thus passivated by the method, so there is no contamination caused by such components. This method also makes it possible to use materials that would normally not be available. For example, it is possible to use a tantalum-coated thermal stabilizer metal such as tantalum or tungsten (they additionally have oxidation resistance). This can then be used to make the relevant components for use in the tantalum melt. However, it is also possible to use quartz glass. This cooling additionally has the advantage of enhancing the heat convection resulting from the cooling in the helium melt by means of an agitator introduced from the upper center. This method also promotes the formation of particles such as S i C and S i N . The problem to be solved by the present invention is also solved by purifying the -12-12-201247535 device in this way. The device comprises at least one heatable vortex, wherein at least one gas feed line is disposed inside the crucible. It is conceivable that the gas feed line comprises at least one filter and/or at least one sintered glass material. The filter or the sintered glass has a pore size of 1 〇μη1 to 1 mm 〇 additionally conceivable at least one connection or connectable to high The induction coil of the frequency generator is disposed around the crucible, and the crucible can be moved out of the induction field in the direction of the coil axis. It is also conceivable to arrange at least one rotatable agitator in the crucible. The crucible melt can be circulated by the rotatable agitator. The apparatus according to the invention may also be characterized in that the gas feed line is integrated with at least one agitator. To this end, the gas feed line can be rotatably mounted. Furthermore, it is contemplated in accordance with the present invention that at least one mixing vane is disposed on the forward end of the gas feed line that projects to the crucible melt. It is also contemplated that the gas feed line and/or the agitator consists essentially of SiO 2 , SiC, tungsten, tungsten carbide and/or niobium, preferably comprising a tantalum coating or consisting of niobium. Furthermore, it is also possible according to the invention to provide a reduction device for reducing the enthalpy, and for controlling or adjusting the reduction speed, the power of the induction coil, the cooling of the at least one gas feed line, the cooling of at least one agitator And/or means for controlling or adjusting the flow of gas of the purified gas. Finally, it is conceivable that the device comprises a large number of insulating layers, preferably comprising graphite -13 - 201247535 cloth, air, graphite, ultra-high temperature insulating material and/or insulating powder, particularly preferably a carbon black bed. A complete process with an additional process step for purifying the crucible and other apparatus for carrying out the apparatus of the invention for carrying out the method of the invention are described in WO 201 0 03 7 694 A2, which is incorporated herein by reference. . The present invention is based on the unexpected discovery that the introduction of a purified gas may promote particle formation and then collect the particles in the detachable solidified ruthenium region due to directional solidification. If the part is removed, the purification of the cockroach can be obtained. In addition, some of the particles formed by the nucleation of the purified gas also float to the surface of the ruthenium melt due to its low density, which is particularly far from the crystallization front and therefore does not interact with the ruthenium in the solidification. Combine. If the particles of the foreign matter formed in the crucible melt are filtered from the crucible melt, a special bonding effect is produced. It has been unexpectedly found that porous ceramics, which can be coated with Si〇2, can be used herein. The filters may simply be immersed in the bismuth melt or a portion of the ruthenium melt may be drawn into or through the filters. The filter must be heated to a temperature at which the crucible is liquid to prevent the filters from quickly blocking. Alternatively, for example, by such a filter, the particles of the foreign matter can be simply poured so that the filtered mash can be returned to the mash melt. The purified gas can be injected into the crucible melt via at least one tube. This purified gas can be used simultaneously to cool the tube. The tube can also be placed in the agitator or in the wall of the crucible. Due to the cooling, a layer of ruthenium can be created on the tube, or the existing ruthenium layer can be stabilized. The tube can of course be cooled by other means. The same kind of boundary layer means that it is possible to prevent the presence of bismuth melt.
-14- 201247535 該管中溶解出來的雜質。若該管係以可旋轉方式安裝，其 可同時用作機械性攪拌器。爲此，可在該管上提供混合葉 片，其可攪拌該矽熔體。 爲了定向凝固矽熔體，可降下該坩堝以離開經加熱區 域’或降低加熱功率，而該坩堝底部之散熱器係用於從該 坩堝底部開始產生定向凝固。可同時降低該經加熱區域之 溫度。熱流及熱阻之溫度梯度係以使得在整個定向凝固中 建立儘可能水平之結晶前緣的方式來建立。 【實施方式】 進行本發明之實例係解釋如下，參考兩個示意圖，但 不限制本發明。 圖1顯示用於本發明方法之本發明裝置的示意橫斷面 圖，其中圓柱形坩堝1之頂部開放，該坩渦容納矽熔體4 °在坩堝1底部區域存在已凝固之矽6。結晶前緣7在矽 熔體4及已凝固之矽6之間形成界面。 線圏8配置在坩堝1周圍，且係連接至高頻產生器（ 未圖示）。從該高頻產生器施加在該線圈8上的交流電壓 產生該線圈8中之高頻交流電磁場。該交流電磁場係結合 至坩堝1及/或矽熔體4及已凝固之矽6，且於該處產生渦 電流。由於線圈8內部之材料1、4、6之電阻，該等渦電 流受減衰且產生熱。 坩堝1可由介電材料製成，使得由線圈8所產生的交 流電磁場通過。然後該交流電磁場直接結合至矽熔體4及 -15- 201247535 /或矽6，因此使得其等自體加熱。 矽4、6及坩堝1中之交流電磁場的穿透深度取決於 交流場之頻率。Hz及MHz範圍之頻率尤其適用。微波頻 率範圍之電磁波不以線圈產生’而是以波導及普通微波產 生器產生，可以替代線圈8或額外於線圈8的方式使用波 導及普通微波產生器。針對待加熱坩堝1之大小來調整頻 率，隨著坩堝直徑增加而選擇較低頻率，如此可產生儘可 能水平之結晶前緣。 在該坩堝底部下方，提供降低裝置1〇，藉由該降低裝 置10使坩堝1在沿著線圈8之對稱軸（圖1中爲垂直線 )的二者方向緩慢且均勻地移動。該降低裝置1 〇可例如 以馬達操作，但亦可以氣動或液壓方式操作。 呈圓柱形管形式之氣體進料管線1 2係配置在矽熔體4 中，且亦用作攪拌棒。在氣體進料管線1 2及/或攪拌棒1 2 底端配置混合葉片14，其可攪拌該矽熔體4。爲此目的， 氣體進料管線12係以可旋轉方式安裝且係以馬達16驅動 和旋轉。 氣體進料管線1 2爲內部中空，因此純化氣體（未圖 示）可泵入該矽熔體4。爲此目的，混合葉片14中之通道 1 8從氣體進料管線1 2內部導至該混合葉片1 4表面，於該 處該純化氣體呈氣泡20形式排放至該矽熔體4中。 氣泡20上升通過該矽熔體4，將之徹底混合，促進外 來物質粒子形成且致使該等外來物質上升至矽熔體4之表 面。結果’在結晶前緣7處，較少雜質結合於該凝固中之 -16- 201247535 砂6。混合葉片14之運動確使純化氣體流更快速冒出’使 得形成更細微氣泡20。外來物質之粒子的浮力亦與矽熔體 非常具流體性相關。 由於液態矽4之液體靜壓，作用在氣泡20上的壓力 隨著氣泡上升至表面而降低。因此’氣泡20之半徑與氣 泡20位於矽熔體4中之深度呈函數關係變化。 氣體進料管線1 2係導至結晶前緣7上方。必須確使 結晶前緣7處之流動充足以攜走集中在結晶前緣7之前緣 的雜質。結晶前緣7前進的速度取決於坩堝1降低之速度 、交流電磁場之功率、攪拌棒12及混合葉片14之角速度 ，以及取決於溫度、體積流率及純化氣體之進料位置。熱 流決定結晶前緣7之形狀。 在降低坩堝1時，結晶前緣7向上前進且從矽熔體4 凝固出矽6。同時，線圏8之功率亦可降低。爲補償當坩 堝1降低時因通過無材料的線圈8內部之交流電磁場的較 差耦合表現，可能使線圈8之功率只稍微降低或甚至必須 提高，如此矽熔體4不會太快凝固。 根據本發明之方法確使於凝固中之矽6中儘可能結合 最少的雜質。結果，經純化之矽6在凝固開始時形成。爲 使該方法期間該矽熔體4中提高之雜質濃度降低，可以過 濾器（未圖示）過濾矽熔體4表面。混合葉片14亦包含 過濾材料。然而，必須確保混合葉片1 4中純化氣體用之 通道18的排出開口不被阻塞。爲防止該區域中的矽熔體4 凝固’可在排出開口上提供材料，在此排出開口矽只不良 -17- 201247535 地凝固。爲了矽熔體4之熱轉移，該溫度（尤其是混合葉 片1 4之外部區域處）足夠高以防止矽在該等區域中凝固 。亦可設想在純化氣體進入矽熔體4之前將之加熱。爲此 ’可在氣體進料管線12中提供加熱裝置，較佳在混合葉 片1 4區域中提供。 當坩堝1中之矽4、6均凝固時，從坩堝1移出。移 除（例如藉由噴砂）或切除較髒之上方區域。留下之塊爲 經純化之砂。 經由本發明之方法，可能在完全凝固之矽的最後凝固 之小區域中收集最大可能量之雜質。同時，可提高定向凝 固發生之速率。 圖2顯示根據本發明用於矽之純化的另一裝置之橫斷 面圖不。該裝置係分成上方加熱區域及下方冷卻區域。 該裝置之最大直徑爲1000 mm。應達成10 mm/h之軸 向結晶速率。此意謂必須爲該裝置選擇充分絕緣，如此在 希望之直徑下，在矽熔體5 1中產生結晶之適當溫度梯度 ，因此適於在矽熔體5 1中提供適當結晶前緣。 在該實例中，冷卻區域之設計係經選擇如表1所述， 表1第一欄顯示數字參考符號，該等參考符號之順序與從 內而外之層順序一致：-14- 201247535 Impurities dissolved in the tube. If the tube is rotatably mounted, it can be used as a mechanical agitator at the same time. To this end, a mixing blade can be provided on the tube which can agitate the crucible melt. To orient the solidified crucible melt, the crucible can be lowered to leave the heated zone or reduce the heating power, and the heat sink at the bottom of the crucible is used to produce directional solidification from the bottom of the crucible. The temperature of the heated zone can be lowered simultaneously. The temperature gradient of heat flow and thermal resistance is established in such a way as to establish as much a crystalline front as possible in the entire directional solidification. [Embodiment] The examples for carrying out the invention are explained below, with reference to two schematic diagrams, but without limiting the invention. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 shows a schematic cross-sectional view of the apparatus of the invention for use in the process of the invention, wherein the top of the cylindrical crucible 1 is open, the crucible containing the crucible 4 ° in the bottom region of the crucible 1 in the solidified crucible 6. The crystallization front 7 forms an interface between the 矽 melt 4 and the solidified crucible 6. The coil 8 is disposed around the crucible 1 and is connected to a high frequency generator (not shown). The alternating voltage applied to the coil 8 from the high frequency generator generates a high frequency alternating current electromagnetic field in the coil 8. The alternating electromagnetic field is coupled to the crucible 1 and/or the crucible melt 4 and the solidified crucible 6 where eddy currents are generated. Due to the resistance of the materials 1, 4, 6 inside the coil 8, the eddy currents are degraded and generate heat. The crucible 1 may be made of a dielectric material such that an alternating electromagnetic field generated by the coil 8 passes. The alternating electromagnetic field is then directly bonded to the bismuth melt 4 and -15-201247535 / or 矽6, thus allowing it to be self-heated. The penetration depth of the AC electromagnetic field in 矽4, 6 and 坩埚1 depends on the frequency of the AC field. Frequency in the Hz and MHz ranges is especially useful. The electromagnetic wave in the microwave frequency range is not generated by the coil' but is generated by the waveguide and the ordinary microwave generator, and the waveguide and the ordinary microwave generator can be used instead of the coil 8 or in addition to the coil 8. The frequency is adjusted for the size of the crucible 1 to be heated, and the lower frequency is selected as the diameter of the crucible increases, thus producing a crystallographic leading edge of the highest possible level. Below the bottom of the crucible, a lowering device 1 is provided, by which the crucible 1 is moved slowly and uniformly in both directions along the axis of symmetry of the coil 8 (vertical line in Fig. 1). The lowering device 1 can be operated, for example, as a motor, but can also be operated pneumatically or hydraulically. A gas feed line 12 in the form of a cylindrical tube is disposed in the crucible melt 4 and is also used as a stir bar. A mixing blade 14 is disposed at the bottom end of the gas feed line 12 and/or the stir bar 12, which can agitate the tantalum melt 4. For this purpose, the gas feed line 12 is rotatably mounted and driven and rotated by a motor 16. The gas feed line 12 is internally hollow so that a purge gas (not shown) can be pumped into the helium melt 4. For this purpose, the passages 18 in the mixing vanes 14 are led from the inside of the gas feed line 12 to the surface of the mixing vanes 14, where the purified gas is discharged into the crucible melt 4 in the form of bubbles 20. The bubble 20 rises through the crucible melt 4 and is thoroughly mixed to promote the formation of foreign matter particles and cause the foreign matter to rise to the surface of the crucible melt 4. As a result, at the crystallization front edge 7, less impurities were incorporated into the solidified -16-201247535 sand 6. The movement of the mixing vanes 14 does cause the purified gas stream to emerge more quickly' to form finer bubbles 20. The buoyancy of the particles of the foreign matter is also very fluidly related to the helium melt. Due to the hydrostatic pressure of the liquid helium 4, the pressure acting on the bubble 20 decreases as the bubble rises to the surface. Thus, the radius of the bubble 20 varies as a function of the depth of the bubble 20 in the crucible melt 4. The gas feed line 12 is directed above the crystallization front edge 7. It is necessary to ensure that the flow at the crystallization front 7 is sufficient to carry away the impurities concentrated on the leading edge of the crystallization front edge 7. The rate at which the crystallization front 7 advances depends on the rate at which the 坩埚1 is lowered, the power of the alternating electromagnetic field, the angular velocity of the stir bar 12 and the mixing blade 14, and the feed position depending on the temperature, volumetric flow rate, and purge gas. The heat flow determines the shape of the crystallization front edge 7. Upon lowering 坩埚1, the crystallization front edge 7 advances upward and solidifies 矽6 from the ruthenium melt 4. At the same time, the power of the coil 8 can also be reduced. In order to compensate for the poor coupling behavior of the alternating electromagnetic field inside the coil 8 without material when the 坩1 is lowered, it is possible to make the power of the coil 8 only slightly lower or even have to be increased, so that the melt 4 does not solidify too quickly. The method according to the invention ensures that as little as possible of the impurities in the crucible 6 during solidification. As a result, the purified hydrazine 6 was formed at the beginning of solidification. In order to reduce the increased impurity concentration in the crucible melt 4 during the process, the surface of the crucible melt 4 may be filtered by a filter (not shown). The mixing blade 14 also contains filter material. However, it is necessary to ensure that the discharge opening of the passage 18 for the purified gas in the mixing blade 14 is not blocked. In order to prevent the solidification of the crucible melt 4 in this area, a material can be provided on the discharge opening, where the discharge opening is only badly solidified -17-201247535. In order to transfer the heat of the crucible 4, the temperature (especially at the outer region of the mixing blade 14) is sufficiently high to prevent solidification of the crucible in the regions. It is also conceivable to heat the purified gas before it enters the ruthenium melt 4. To this end, a heating device can be provided in the gas feed line 12, preferably in the region of the mixing vanes 14. When 矽4 and 6 in 坩埚1 are both solidified, they are removed from 坩埚1. Remove (for example by sandblasting) or cut off the dirty upper area. The remaining block is purified sand. By the method of the present invention, it is possible to collect the largest possible amount of impurities in a small area where the final solidification of the crucible is completely solidified. At the same time, the rate at which directional solidification occurs can be increased. Figure 2 shows a cross-sectional view of another apparatus for purification of hydrazine in accordance with the present invention. The device is divided into an upper heating zone and a lower cooling zone. The device has a maximum diameter of 1000 mm. Axial crystallization rate of 10 mm/h should be achieved. This means that sufficient insulation must be chosen for the device, such that at the desired diameter, a suitable temperature gradient of crystallization is produced in the ruthenium melt 51 and is therefore suitable for providing a suitable crystallization front in the ruthenium melt 51. In this example, the design of the cooling zone is selected as described in Table 1, and the first column of Table 1 shows the numerical reference symbols, the order of which is consistent with the order of the layers from the inside out:
S -18- 201247535 表1 :本發明之分層 編 號 材料 厚度 λ λ 半徑 無cr之 酿 具cr 之酿 [-1 Η mm mW/ (m.°K) kcal/ (m.h°K) mm °C °C 51 Si熔體 70 70 1750 1410 52 玻化釉 70 475 0.41 100 1750 1410 53 石墨坩堝 30 100000 86.04 170 1531 1241 54 空氣間隙 10 熱輻射 180 1530 1240 55 石墨布 80 365 0.31 260 1335 1090 56 石墨環 10 100000 86.04 270 1334 1090 57 絕緣粉末 75 40 0.03 345 138 168 58 石墨環 10 100000 86.04 355 138 168 59 石墨布 80 365 0.31 435 30 85 60 鋼環 2.5 5200 44.74 437.5 30 85 61 水冷卻 60 52000 0.5 497.5 24 52 62 鋼環 2.5 5200 44.74 500 24 52 如此，例如石墨布5 5、5 9及絕緣粉末5 7可供選擇作S -18- 201247535 Table 1: Thickness of the layered material of the present invention λ λ radius of the brewer without radius cr [-1 Η mm mW / (m. °K) kcal / (mh °K) mm °C °C 51 Si melt 70 70 1750 1410 52 Vitrified glaze 70 475 0.41 100 1750 1410 53 Graphite crucible 30 100000 86.04 170 1531 1241 54 Air gap 10 Thermal radiation 180 1530 1240 55 Graphite cloth 80 365 0.31 260 1335 1090 56 Graphite ring 10 100000 86.04 270 1334 1090 57 Insulating powder 75 40 0.03 345 138 168 58 Graphite ring 10 100000 86.04 355 138 168 59 Graphite cloth 80 365 0.31 435 30 85 60 Steel ring 2.5 5200 44.74 437.5 30 85 61 Water cooling 60 52000 0.5 497.5 24 52 62 steel ring 2.5 5200 44.74 500 24 52 Thus, for example, graphite cloth 5 5, 5 9 and insulating powder 57 can be selected for
爲絕緣材料，視絕緣材料等級而定，其分別可用至1 400°C 及1 200°C之最高溫度。使用石墨布55以在粉末絕緣57低 於1 400°C之前用於保持該溫度。亦可能使用其他超高溫絕 緣材料，例如得自Polytec之Ker. 310-1或3360 UHT，來 替代石墨布55及石墨環56。 降入石墨坩堝之底部區域係由超高溫絕緣材料65所 製成。在該層狀絕緣體上方存在感應爐66，矽於其中熔融 ，然後降至矽結晶之絕緣區域。該加熱區域或感應爐66 係覆蓋有外罩67，該外罩67係由耐熱材料所組成。該加 -19- 201247535 熱區域係藉由底板68而接近底部’該底板68中存在具有 矽熔體5 1之石墨坩堝5 3能通過的開口。在頂部’氣體係 經由結晶前緣上方之氣體進料管線7 2進料至該矽熔體內 。以氣泡形式通過矽熔體5 1之氣體用以純化結晶前緣區 域中之矽熔體51。氣體管線72主要由Si02所構成。爲降 低矽熔體51，提供可軸向移動之板73’於其上配置石墨 坩堝5 3。 在本發明方法中，可區分兩種不同階段： —將過熱之矽熔體5 1 ( 1 7 5 0 °C )冷卻至結晶溫度（1 4 1 0 °C )之階段，及 -結晶階段，該矽熔體51之溫度保持幾乎恆定（141 0°C )0 直到結晶之冷卻階段應儘可能短。另一方面，希望緩 慢受控之結晶，以能控制該生長矽晶體之方向及大小。由 於第二項需求決定本方法的成功結果，故其在此爲優先。 在二者情況下，必須提取出存在的熱，且其先快速通 過該絕緣層54、55、56、57、58、59並在最外面的水通 道61中將之導離。可使用碳黑床作爲絕緣粉末57。必須 謹記該最有效之絕緣層可曝露於最高爲1400°C之溫度，且 該鋼環60之鋼只能曝露於約600 °C至70 0°C。此外，該鋼 環60之壁（水冷卻開始處）的溫度不應高於1 〇〇°C以避免 蒸發。 表1所顯示之分層可使得將坩堝降低至冷卻及結晶區 域的速度爲4.2mm/min且結晶速率爲49mm/h。 -20- 201247535 較低之降低速度及較高之結晶速率是相反的目標，彼 等不容易利用鈍化熱絕緣而同時獲致。 由於空氣的熱容量低及該等非常高之溫度，空氣冷卻 並不適用。無加壓之水冷卻只能在低於1 oo°c蒸發溫度之 下進行。 爲獲致較低結晶速率，可進一步加強鈍化絕緣54、55 、56、57、58、59。然而單獨使用石墨布55、59及絕緣 粉末57造成該裝置之較大直徑。 或者’可使用有效且受控制之冷卻，例如使用蒸發溫 度遠高於水之油來冷卻。此需要溫度受控制之油循環，需 要額外組件，例如恆溫器、泵、熱交換器及其他。此種具 有適當設計及控制的裝置使得下降至下方冷卻區域之速度 可能更快。 在17°C之入口溫度下，水冷卻之最小體積流率爲〇.2 m3/h。 茲將以另一實例來解釋本發明，該實例無圖示但具有 類似設計。 將2.5 kg之矽置入石英坩堝中，該石英坩堝係嵌入感 應爐（如同可得自Degussa者）中，且將該砂溶融。在已 達到約1 5 5 0°C之熔融溫度（以嵌入保護石英管中之pt/pt 熱電偶來測量）之後’將配備有石英玻璃燒結玻料之石英 玻璃沖洗氣體單元通至該矽熔體，浸入矽熔體中之體積流 率爲約8 Ι/min之Ar/H2〇混合物（99體積％氬及1體積％ 水），且沖洗約20分鐘》 -21 - 201247535 在該沖洗氣體單元浸入之前，取得「〇」樣本。所使 用之矽熔體具有大於約0.5 ppm之比例的下列元素：c( 28 ppm ) ' A1 ( 37 ppm ) 、Ca ( 4.3 ppm ) 、Cr ( 1.3 ppm )、C u ( 6.2 ppm) 、F e ( 140 ppm ) 、Mg ( 3.6 ppm)、 Ni ( 4.1 ppm ) 、S ( 0.8 ppm ) 、Sn ( 0.6 ppm ) 、Ti ( 2.7 ppm ) 、Zn ( 0.6 ppm) 、Zr ( 1.1 ppm )。 在2 0分鐘沖洗時間之後，取得另一樣本。該經純化 之樣本具有下列最大比例之上述元素：C ( 42 ppm ) 、A1 (12 ppm ) 、C a ( 2.1 ppm ) 、Cr ( 0.7 ppm ) 、Cu ( 1.1 ppm) 、Fe ( 42 ppm ) 、Mg ( 0.9 ppm ) 、N i ( 1.2 ppm ) 、S ( 0.2 ppm ) 、Sn ( < 0.03 ppm ) 、Ti ( 0.8 ppm ) 、Zn (0.06 ppm) 、Zr( 0.3 ppm)。二者樣本均以輝光放電質 譜法（GDMS )來分析。 如此，令人意外的是藉由本發明之純化方法可相當大 幅減少金屬雜質。亦可看出碳之含量增加。碳及/或含碳 化合物浮出，且根據本發明，可藉由簡單方法從該矽熔體 表面予以移除。此特別被視爲根據本發明之令人意外的本 發明發現。 藉由本發明之方法，可能在完全凝固之矽的最後凝固 之小區域中收集到最大量之雜質。同時，可提高定向凝固 發生之速率。 前述說明及申請專利範圍、圖式及實例中所揭示之本 發明特徵可個別以及用於實現本發明各種不同具體實例之 每一組合二者情況下均相當重要。Insulation materials, depending on the grade of insulation, can be used up to a maximum temperature of 1 400 ° C and 1 200 ° C. A graphite cloth 55 was used to maintain this temperature before the powder insulation 57 was lower than 1 400 °C. It is also possible to use other ultra-high temperature insulating materials, such as Ker. 310-1 or 3360 UHT from Polytec, in place of graphite cloth 55 and graphite ring 56. The bottom region of the graphite crucible is made of ultra-high temperature insulating material 65. An induction furnace 66 is present above the layered insulator, where it melts and then falls to the insulating region of the ruthenium crystal. The heating zone or induction furnace 66 is covered with a cover 67 which is composed of a heat resistant material. The -19-201247535 hot zone is near the bottom by the bottom plate 68. The bottom plate 68 has an opening through which the graphite crucible 5 having the crucible melt 51 can pass. The top 'gas system is fed into the helium melt via a gas feed line 72 above the crystallization front. The gas passing through the enthalpy melt 51 in the form of bubbles is used to purify the ruthenium melt 51 in the crystallization front region. The gas line 72 is mainly composed of SiO 2 . To lower the crucible melt 51, an axially movable plate 73' is provided with graphite crucibles 5 3 disposed thereon. In the process of the invention, two different stages can be distinguished: - cooling of the superheated helium melt 5 1 (1,750 ° C) to the crystallization temperature (1 4 1 0 ° C), and - the crystallization stage, The temperature of the crucible melt 51 remains almost constant (141 0 ° C) 0 until the cooling phase of crystallization is as short as possible. On the other hand, it is desirable to slow the controlled crystallization to control the direction and size of the grown ruthenium crystal. Since the second requirement determines the successful outcome of the method, it is prioritized here. In either case, the heat present must be extracted and quickly passed through the insulating layers 54, 55, 56, 57, 58, 59 and directed away in the outermost water channel 61. A carbon black bed can be used as the insulating powder 57. It must be borne in mind that the most effective insulation layer can be exposed to temperatures up to 1400 ° C, and the steel of the steel ring 60 can only be exposed to temperatures from about 600 ° C to 70 ° C. In addition, the temperature of the wall of the steel ring 60 (at the beginning of water cooling) should not be higher than 1 〇〇 ° C to avoid evaporation. The delamination shown in Table 1 was such that the enthalpy was lowered to a cooling and crystallization zone at a rate of 4.2 mm/min and a crystallization rate of 49 mm/h. -20- 201247535 Lower reduction speeds and higher crystallization rates are the opposite targets, and they are not easily achieved with passivation thermal insulation. Air cooling is not suitable due to the low heat capacity of the air and these very high temperatures. Unpressurized water cooling can only be carried out at temperatures below 1 oo °c. Passivation insulation 54, 55, 56, 57, 58, 59 can be further enhanced to achieve a lower crystallization rate. However, the use of graphite cloth 55, 59 and insulating powder 57 alone results in a larger diameter of the device. Alternatively, effective and controlled cooling can be used, for example, using an oil having a vaporization temperature much higher than water. This requires a temperature controlled oil cycle that requires additional components such as thermostats, pumps, heat exchangers and others. This type of device with proper design and control makes it possible to descend to the lower cooling zone at a faster rate. At an inlet temperature of 17 ° C, the minimum volumetric flow rate of water cooling is 〇.2 m3/h. The invention will be explained by another example which is not illustrated but has a similar design. A 2.5 kg crucible was placed in a quartz crucible embedded in an induction furnace (as available from Degussa) and the sand was melted. After the melting temperature of about 1550 ° C (measured by a pt/pt thermocouple embedded in a protective quartz tube) has been reached, 'the quartz glass flushing gas unit equipped with the quartz glass sintered glass is passed to the crucible. , a volumetric flow rate of about 8 Ι/min of Ar/H2 〇 mixture (99 vol% argon and 1 vol% water), and rinsing for about 20 minutes. -21 - 201247535 in the flushing gas unit Obtain a "〇" sample before immersing. The ruthenium melt used has the following elements in a ratio of greater than about 0.5 ppm: c (28 ppm) 'A1 (37 ppm), Ca (4.3 ppm), Cr (1.3 ppm), C u (6.2 ppm), F e (140 ppm), Mg (3.6 ppm), Ni (4.1 ppm), S (0.8 ppm), Sn (0.6 ppm), Ti (2.7 ppm), Zn (0.6 ppm), Zr (1.1 ppm). After the 20 minute rinse time, another sample was taken. The purified sample has the following maximum proportions of the above elements: C (42 ppm), A1 (12 ppm), C a (2.1 ppm), Cr (0.7 ppm), Cu (1.1 ppm), Fe (42 ppm), Mg (0.9 ppm), N i (1.2 ppm), S (0.2 ppm), Sn (< 0.03 ppm), Ti (0.8 ppm), Zn (0.06 ppm), Zr (0.3 ppm). Both samples were analyzed by glow discharge mass spectrometry (GDMS). Thus, it is surprising that the metal impurities can be considerably reduced by the purification method of the present invention. It can also be seen that the carbon content is increased. The carbon and/or carbonaceous compound floats out and can be removed from the surface of the crucible melt by a simple method in accordance with the present invention. This is particularly seen as an unexpected discovery of the present invention in accordance with the present invention. By the method of the present invention, it is possible to collect a maximum amount of impurities in a small area where the final solidification of the crucible is completely solidified. At the same time, the rate at which directional solidification occurs can be increased. The above description and the features of the invention as disclosed in the claims, the drawings and the examples of the invention can be considered individually and in the context of each of the various embodiments of the invention.
-22- 201247535 【圖式簡單說明】 圖1 :根據本發明用於矽之純化的裝置之橫斷面圖示 :及 圖2 :根據本發明用於矽之純化的另一裝置之橫斷面 圖示。 【主要元件符號說明】 1 :坩堝 4 :矽熔體 6 :凝固之矽 7 :結晶則緣 8 :線圈 1 〇 :降低裝置 1 2 :氣體進料管線及攪拌棒 1 4 :混合葉片 1 6 :馬達 18 :通道 20 :氣泡 5 1 :矽熔體 5 2 :玻化釉 5 3 :石墨坩堝 5 4 :空氣間隙 55 :石墨布 -23- 201247535 56 :石墨環 5 7 :絕緣粉末 58 :石墨環 59 :石墨布 6 0 :鋼環 6 1 :水冷卻 6 2 :鋼環 65 :超高溫絕緣材料 6 6 :感應爐 6 7 :外罩 6 8 :底板 72 :氣體進料管線 73 :板 -24-22- 201247535 BRIEF DESCRIPTION OF THE DRAWINGS Figure 1: Cross-sectional illustration of a device for purification of hydrazine according to the present invention: and Figure 2: Cross section of another device for purification of hydrazine according to the present invention Illustration. [Main component symbol description] 1 : 坩埚 4 : 矽 melt 6 : solidification 矽 7 : crystallization edge 8 : coil 1 〇 : reduction device 1 2 : gas feed line and stirring rod 1 4 : mixing blade 1 6 : Motor 18: Channel 20: Bubble 5 1 : 矽 Melt 5 2 : Vitrified glaze 5 3 : Graphite 坩埚 5 4 : Air gap 55 : Graphite cloth -23 - 201247535 56 : Graphite ring 5 7 : Insulation powder 58 : Graphite ring 59: graphite cloth 60: steel ring 6 1 : water cooling 6 2 : steel ring 65 : ultra high temperature insulating material 6 6 : induction furnace 6 7 : outer cover 6 8 : bottom plate 72 : gas feed line 73 : plate - 24