201137952 六、發明說明： 【發明所屬之技術領域】 本發明涉及用於藉由雷射來摻雜基板的一種裝置及一 種方法，其中在該方法中，至少一種摻雜劑與該基板表面 係相接觸的並且該基板表面藉由一雷射束局部地被加熱。 【先前技術】 〇 工業上在實踐中，所提及屬類的裝置總體上係批次加 熱爐或連續摻雜裝置，其中太陽能電池基板被加熱到用於 摻雜劑擴散所要求的大於8 00 °C的溫度。在摻雜太陽能電 池發射極的情況下，存在著由摻雜造成的在某種程度上矛 盾的要求，正如在例如文件DE 10 2007 035 068中所描述 的。在光學上開放的區域，這種摻雜必須不太高，因爲非 常高的摻雜原子濃度促進了電子-電洞對的再結合並且因 此阻礙了所希望的太陽能電池的高效率。另一方面，在連 〇 接電極的接觸區域’特別地，非常高的摻雜對於產生所要 求的歐姆接觸係必須的。該等矛盾的要求最近主要在實驗 室樣品中導致在接觸區域以及所謂的選擇性發射極中實現 了更高度摻雜的區域。該等選擇性發射極的生產在使用習 知的方法來實現時經常要求不經濟的高花費。 在近些年還開發了用於摻雜半導體的雷射裝置。文件 DE 1 0 2004 03 6 22〇 B4描述了雷射摻雜方法來作爲習知的 加熱爐摻雜方法的替代’其優點主要在於以下事實：處理 時間以及:程供給系統（1 〇 g i s t i c s )比在加熱爐法中更有 -5- 201137952 利，並且在雷射方法的情況下能量效率更高。然而，所述 文件中描述的方法總體上具有以下問題：雷射摻雜的基板 具有高的位錯密度以及低品質。 該文件在該表面的熔化並且再結晶之後由以下事實解 決了高位錯密度的問題：將雷射束聚焦於具有1 0 μπι寬度 以及1 00 μιη長度的一條線並且這個線焦點掃描了該基板的 表面。對這種方法可以提及的缺點係低處理速度以及用於 實現可靠的自動聚焦系統的技術花費。這種摻雜所尋求的 特徵係基於在加熱爐方法中產生的該等摻雜的特徵。這就 是說尋求達1微米的範圍作爲摻雜的深度。從光在矽中的 取決於波長的已知穿透深度，因此推斷出必須使用具有的 波長爲600 nm或更低的雷射輻射。 用於摻雜的批次裝置目前在矽太陽能電池的生產中是 標準的。缺點包括在該等裝置上較長的處理時間以及大的 機械尺寸。可控制的溫度被限制在小於1 〇〇〇°C，並且整體 基板的加熱導致了藉由基板背面引入污染的問題。在習知 的摻雜方法中另一問題係儘管摻雜劑擴散進入該矽晶體中 ，但是它們基本上沒有被結合在晶格位點並被電活化。 【發明內容】 本發明的目的係提供一雷射摻雜方法，該方法使之有 可能以高速摻雜基板，同時在該基板表面上產生低的位錯 密度，以實現摻雜劑的良好電活化並且進一步以一定向方 式更高地提供對摻雜特定區域的選擇。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus and a method for doping a substrate by laser, wherein in the method, at least one dopant is phased with the surface of the substrate The substrate is contacted and the surface of the substrate is locally heated by a laser beam. [Prior Art] In the industry, in practice, the devices of the generic type are generally batch furnaces or continuous doping devices in which the solar cell substrate is heated to more than 800 00 for dopant diffusion. °C temperature. In the case of a doped solar cell emitter, there is a requirement for a certain degree of contradiction caused by doping, as described, for example, in the document DE 10 2007 035 068. In optically open regions, this doping must be less high because very high doping atom concentrations promote recombination of electron-hole pairs and thus hinder the high efficiency of the desired solar cell. On the other hand, in the contact area of the junction electrode, in particular, very high doping is necessary to produce the desired ohmic contact system. These contradictory requirements have recently led to the implementation of more highly doped regions in the contact regions and in the so-called selective emitters, primarily in laboratory samples. The production of such selective emitters often requires uneconomical high costs when implemented using conventional methods. Laser devices for doping semiconductors have also been developed in recent years. Document DE 1 0 2004 03 6 22〇B4 describes a laser doping method as an alternative to the conventional furnace doping method. The advantages are mainly due to the fact that the processing time and the ratio of the process supply system (1 〇gistics) In the furnace method, there is more than -5 - 201137952, and in the case of the laser method, the energy efficiency is higher. However, the method described in the document generally has the following problems: the laser doped substrate has high dislocation density and low quality. This document solves the problem of high dislocation density after the surface is melted and recrystallized by focusing the laser beam on a line having a width of 10 μm and a length of 100 μm and this line focus scans the substrate. surface. Disadvantages that can be mentioned for this method are low processing speeds and the technical cost of implementing a reliable autofocus system. The characteristics sought for such doping are based on the characteristics of the doping produced in the furnace method. This means that a range of up to 1 micron is sought as the depth of doping. From the known penetration depth of light depending on the wavelength of light, it is inferred that it is necessary to use laser radiation having a wavelength of 600 nm or less. Batch devices for doping are currently standard in the production of tantalum solar cells. Disadvantages include longer processing times and large mechanical sizes on such devices. The controllable temperature is limited to less than 1 〇〇〇 ° C, and heating of the integral substrate causes contamination problems introduced by the back side of the substrate. Another problem in the conventional doping method is that although dopants diffuse into the germanium crystal, they are not substantially bound to the lattice sites and are electrically activated. SUMMARY OF THE INVENTION An object of the present invention is to provide a laser doping method which makes it possible to dope a substrate at a high speed while generating a low dislocation density on the surface of the substrate to achieve good electrical conductivity of the dopant. The selection of the doping specific regions is activated and further provided in a certain direction.
S -6 - 201137952 • 這個目的係藉助以上提及類屬的一裝置實現的，其中 該裝置具有至少一個光纖雷射器以及一掃描器單元，該光 纖雷射器具有一擁有圓形射束截面的雷射束，藉由該掃描 器單元，該基板表面可以藉助該雷射束被掃描，該光纖雷 射器的發射光具有的波長係在750 nm至3000 nm的範圍內 〇 光纖雷射器係雷射技術領域中一項最近的發展。該等 〇 新穎的雷射器因非常高的性能以及非常高的射束品質結合 低的價格而突出。這一新類別的雷射器的高性能使之有可 能在雷射摻雜裝置的構造中遵循新的路徑。它不再是以下 這種情況：對於處理所要求的能量僅可以在焦點處局部地 提供’而是有可能使用一雷射束，其圓形射束截面具有的 尺寸係20至5 00 μιη並且該截面在大約！ min的習知射束長度 範圍中係可得的。該等雷射器的功率適合用於處理光電基 板的全部基板面積。 〇 在將根據本發明的雷射摻雜裝置的能量效率與一習知 的加熱爐摻雜裝置進行比較時，根據本發明的雷射摻雜裝 置具有該優點。在光纖雷射器中，光束係以高效率產生的 ’並且在該雷射摻雜方法中的光能量得到有效地利用，因 爲僅僅基板的表面而不是整個基板被加熱。防止該基板經 受摻雜過程中的熱負荷還爲太陽能電池的總體技術打開了 的新的可能性。因此’不同於加熱爐摻雜，這種雷射摻雜 可以在該總體技術中的一後面的步驟中完成，其中該基板 已經具有了溫敏元件。這個優點主要在更複雜的技術中並 201137952 且例如在兩面電池槪念中是有益的。使用雷射摻雜裝置還 有可能順序地並且在該等基板的兩個表面上進行多個摻雜 過程。 與習知的加熱爐摻雜裝置相比，不僅能量被更有效地 利用，並且該等摻雜劑也更有效地被送到它們的半導體摻 雜任務中。該等摻雜劑沒有不希望地被結合在該表面的間 隙位置，而是由於更高溫度的結果它們被有利地且有效地 結合在晶格位點。由於這種更有效的利用，摻雜劑的更小 施用係足夠的。 爲了遍佈該基板表面而移動雷射束，根據本發明另外 有可能使用合適的可商購的掃描器單元，該等單元能以必 須的精確度和速度來移動該光束。在這種情況下該等掃描 器的速度可以改變，這樣除了遍及這整個面積的均勻處理 之外’局部化的處理也是有可能的。 這種雷射方法可以非常靈活地進行控制、調整並且優 化’因爲該掃描器單元以及該光纖雷射器兩者本身都可以 非常靈活地操作。包括光纖雷射器以及掃描器單元的這個 系統的特性意味者可以靈活地監測該基板中的摻雜區域的 深度。可以精確地設定摻雜的特性輪廓以及電阻。其結果 係，使用根據本發明的雷射摻雜裝置可以給出改進的產品 ’例如改進的太陽能電池。 除了在實際摻雜過程中的優點之外，使用雷射摻雜還 導致了在處理的邊緣上的進一步的優點。因爲該等基板表 面由於碰撞雷射束的結果而非常迅速地變熱’因此對於該 -8 - 201137952 等基板不要求預熱階段以及冷卻階段。其結果係，更快速 的整體過程變得有可能。此外，根據本發明的雷射摻雜裝 置可以使用比一摻雜加熱爐更小的空間尺寸來實現。使用 雷射摻雜裝置時空間的節省導致了在建立製造裝置中的成 本優勢。 根據本發明，這種雷射摻雜裝置使用了發射的光具有 7 5 0至3 000 nm範圍內波長的一光纖雷射器。成熟的光纖雷 〇 射器存在於這個波長範圍中。然而，這個波長範圍最初似 乎不適合用於處理矽基板，因爲矽在這個範圍內是透明的 。然而在一光纖雷射器束中高功率密度的結果係，基板的 表面被迅速加熱，從而發生了容積激發的熱聚集的效應。 該等基板的光學特性由於材料加熱而改變。在矽的情況下 ，吸收增加。結果，穿透深度降低了。這種穿透深度甚至 可以藉由設定合適的參數如功率、掃描速度、脈衝能量以 及脈衝持續時間或重複率而調節到所希望的範圍。矽基板 〇 可以使用在這個波長範圍內的雷射摻雜裝置而非加熱爐方 法進行更深地摻雜。在太陽能電池的生產中並且確切地是 在太陽能電池發射極的磷摻雜過程中，因此有可能實現在 例如1至1 〇 μπι範圍內的摻雜深度。對太陽能電池製成的接 觸以及總效率可以由於更高的摻雜深度結合該深度上的均 勻摻雜而得到改進。 原則上，還有可能使用發射的光在5〇〇至600 nm波長 範圍的一光纖雷射器。在這個波長範圍內的光纖雷射器僅 在一段短的時間中是可商購的。在這個更短波長範圍內操 5 -9- 201137952 作的裝置特別對於希望小的摻雜深度的應用是引起興趣的 〇 在本發明的一較佳實施例中，所使用的光纖雷射器係 一連續波雷射器或係一具有在8 0 n S至1 ο μ s範圍內的相對 長脈衝長度的脈衝雷射器。在該等條件下，不伴隨其晶體 構造淺顯地受損的一基板摻雜係有可能的。此外，該等摻 雜劑被很好地結合在該基板晶體中並且被電活化。例如5 kW的特別高的功率在連續波的操作中是可供使用的。因 此使用連續波雷射器對於快速且有成本效益的處理係特別 有利的。例如僅300 W的更低功率在脈衝操作中是可供使 用的。脈衝操作中的優點係另外的可供使用的參數。因此 ，有可能對摻雜劑共用（dopant sharing)具有更大影響， 例如藉助脈衝形狀、脈衝持續時間、重複率以及空間的脈 衝與脈衝重疊。 在本發明的一適宜發展中，該裝置具有多個光纖雷射 器和/或至少一個分束器，該分束器用於產生多個部分雷 射束來形成一種多束配置。爲了增大該裝置的輸送量，使 用多個平行操作的雷射器可能是適宜的。因此，可以使用 該分束器將一大功率雷射束（在一射束中不要求其總功率 )分離成多個部分雷射束，由此能夠用多個雷射束或部分 雷射束以及因此更高的處理速度來同時處理該基板。 在根據本發明的一特定的實施例中，這種雷射摻雜裝 置使用了一繞射元件用於全像射束分離成5 〇至4 0 0個部分 雷射束。將這種分束器與對應的任務進行協調。作爲舉例S -6 - 201137952 • This object is achieved by means of a device of the above mentioned generic type, wherein the device has at least one fiber laser and a scanner unit having a circular beam cross section a laser beam by which the surface of the substrate can be scanned by means of the scanner beam, the emitted light of the fiber laser having a wavelength in the range of 750 nm to 3000 nm, and a fiber laser system A recent development in the field of laser technology. These newer lasers stand out for their high performance and very high beam quality combined with low prices. The high performance of this new class of lasers makes it possible to follow new paths in the construction of laser doping devices. It is no longer the case that the energy required for the treatment can only be provided locally at the focus 'but it is possible to use a laser beam whose circular beam section has a size of 20 to 500 μm and The section is around! The range of the known beam length of min is available. The power of the lasers is suitable for processing the entire substrate area of the photovoltaic substrate. The laser doping device according to the present invention has this advantage when comparing the energy efficiency of the laser doping device according to the present invention with a conventional furnace doping device. In a fiber laser, the beam is produced with high efficiency and the light energy in the laser doping method is effectively utilized because only the surface of the substrate, rather than the entire substrate, is heated. Preventing the substrate from undergoing thermal loading during the doping process also opens up new possibilities for the overall technology of solar cells. Thus, unlike furnace doping, such laser doping can be accomplished in a later step in the overall art where the substrate already has a temperature sensitive element. This advantage is mainly in more complex technology and 201137952 and is useful, for example, in two-sided battery mourning. It is also possible to perform a plurality of doping processes sequentially and on both surfaces of the substrates using a laser doping device. Not only is energy utilized more efficiently than conventional furnace doping devices, but the dopants are also more efficiently delivered to their semiconductor doping tasks. The dopants are not undesirably bonded to the interstitial sites of the surface, but they are advantageously and efficiently bound to the lattice sites as a result of higher temperatures. Due to this more efficient use, a smaller application of the dopant is sufficient. In order to move the laser beam throughout the surface of the substrate, it is further possible according to the invention to use suitable commercially available scanner units which are capable of moving the beam with the necessary precision and speed. In this case the speed of the scanners can be varied so that localized processing is possible in addition to uniform processing throughout the entire area. This laser method can be controlled, adjusted and optimized with great flexibility' because both the scanner unit and the fiber laser itself can operate very flexibly. The nature of this system, including the fiber laser and the scanner unit, means that the depth of the doped regions in the substrate can be flexibly monitored. The characteristic profile of the doping as well as the resistance can be precisely set. As a result, an improved product such as an improved solar cell can be given using the laser doping device according to the present invention. In addition to the advantages in the actual doping process, the use of laser doping also leads to further advantages at the edge of the process. Because the surface of the substrate heats up very rapidly as a result of colliding with the laser beam, the preheating phase and the cooling phase are not required for substrates such as -8 - 201137952. As a result, a faster overall process becomes possible. Furthermore, the laser doping device according to the invention can be realized using a smaller spatial dimension than a doping furnace. The space savings when using a laser doping device results in a cost advantage in establishing a manufacturing device. According to the invention, such a laser doping device uses a fiber laser that emits light having a wavelength in the range of 75 to 3,000 nm. Mature fiber-optic lightning detectors exist in this wavelength range. However, this wavelength range initially seems unsuitable for processing germanium substrates because germanium is transparent in this range. However, as a result of the high power density in a bundle of fiber lasers, the surface of the substrate is rapidly heated, so that the effect of heat accumulation by volume excitation occurs. The optical properties of the substrates vary due to material heating. In the case of sputum, absorption increases. As a result, the penetration depth is lowered. This penetration depth can be adjusted to the desired range even by setting appropriate parameters such as power, scanning speed, pulse energy, and pulse duration or repetition rate. The ruthenium substrate 〇 can be deeper doped using a laser doping device in this wavelength range instead of the furnace method. In the production of solar cells and specifically in the phosphorous doping process of the solar cell emitter, it is therefore possible to achieve a doping depth in the range of, for example, 1 to 1 〇 μπι. The contact made to the solar cell and the overall efficiency can be improved due to the higher doping depth combined with uniform doping at this depth. In principle, it is also possible to use a fiber laser that emits light in the wavelength range from 5 600 to 600 nm. Fiber lasers in this wavelength range are commercially available only for a short period of time. Devices operating in this shorter wavelength range 5-9-201137952 are of particular interest for applications where a small doping depth is desired. In a preferred embodiment of the invention, the fiber laser system used A continuous wave laser or a pulsed laser having a relatively long pulse length in the range of 80 n S to 1 ο μ s. Under these conditions, a substrate doping that is not accompanied by a shallow damage to its crystal structure is possible. Moreover, the dopants are well incorporated in the substrate crystal and are electrically activated. For example, a particularly high power of 5 kW is available for continuous wave operation. The use of continuous wave lasers is therefore particularly advantageous for fast and cost effective processing systems. For example, a lower power of only 300 W is available for use in pulse operation. The advantages in pulse operation are additional parameters that are available for use. Therefore, it is possible to have a greater influence on dopant sharing, for example, by pulse shape, pulse duration, repetition rate, and spatial pulse and pulse overlap. In a suitable development of the invention, the apparatus has a plurality of fiber lasers and/or at least one beam splitter for generating a plurality of partial laser beams to form a multi-beam configuration. In order to increase the throughput of the device, it may be desirable to use a plurality of lasers operating in parallel. Therefore, the beam splitter can be used to separate a large power laser beam (no total power is required in one beam) into a plurality of partial laser beams, thereby enabling the use of multiple laser beams or partial laser beams And thus a higher processing speed to simultaneously process the substrate. In a particular embodiment in accordance with the invention, such a laser doping device uses a diffractive element for holographic beam splitting into 5 〇 to 400 partial laser beams. This beam splitter is coordinated with the corresponding task. As an example
S -10 - 201137952 ，可以藉助這樣一分離的射束將許多選擇性發射極的指狀 區寫在太陽能基板上。在這種情況下，該分束器較佳在結 構上被適配至該等指狀區的配置。一太陽能電池的接觸電 極除該等指狀區之外還包括主線，所謂的“匯流條”，該等 各別指狀區的變化被收集在其上。太陽能電池的選擇性發 射極既在各別指狀區的區域中又在該等“匯流條”的區域中 形成。在這種情況下，該雷射摻雜過程被再分爲用於刻寫 0 該等各別指狀區以及“匯流條”的多個工作步驟。摻雜深度 在該雷射摻雜過程中可以改變，這可以用來例如在一選擇 性發射極的生產過程中的各別工作步驟中形成更深的摻雜 0 在本發明的另一有利的變體中，該掃描器單元具有至 少一個快速掃描器，它可以是例如一檢流計掃描器（ galvo-scanner)、一多邊形掃描器和/或一共振掃描器。這 樣一快速掃描器使能在滿足生產要求的大面積基板上得到 〇 足夠高的處理速度。可以根據所使用的雷射器以及計畫的 雷射束移動來選擇該等掃描器部件。對目前可獲得的行進 速度的指導値，使用重複率達1 MHz的脈衝雷射器係20 m/s，使用連續雷射器係400 m/s。 在用於摻雜基板的一適宜的實施例中，該掃描器單元 具有在至少兩個基板上延伸的掃描範圍。如果在該裝置中 處理相對小的基板例如像晶片、並且例如在一基板支架上 處理7 X 8的晶片，則這在該掃描器單元具有同該基板支架 一樣大的掃描範圍時是特別適宜的，因爲在這種情況下每 -11 - 201137952 台裝置僅僅必須結合一光纖雷射器以及一掃描器單元。然 而’該處理範圍還可以在兩個或多個雷射束之間劃分，然 後每個雷射束具有小於該基板支架的掃描範圍。 在一發展中，根據本發明的裝置具有至少一個用於使 該等基板處於該雷射器掃描範圍內的定位裝置和/或至少 一個用於該等基板的監測裝置。如果該等基板旨在不僅在 整個面積上進行處理而且還旨在以一局部限定的方式經歷 具體的處理’則必要的是該等基板相對於該掃描器單元被 精確地定位。爲了在該雷射摻雜裝置中確保這種高的定位 精確度，可以將習知技術中獲知的一定位裝置整合到該雷 射摻雜模組中，或者可以將該定位裝置配置在運輸方向上 的該雷射摻雜模組的上游，在此情況下，則必須使用具有 精確的基板位置轉移的運輸系統。 此外，在一適宜的發展中，可以提供用於已完成的摻 雜的一監測裝置。所述監測裝置可以是從習知技術中獲知 的用於光學或電的表面表徵的一測量裝置。精確的基板位 置轉移再次對於將測量値正確地分配在其位置上是必須的 〇 此外，所說明的目的係藉助一用於摻雜基板的方法實 現的，其中至少—種摻雜劑與該基板表面係相接觸的並且 該基板表面藉由一雷射束被局部地加熱。在這種情況下’ 使用了一光纖雷射器’該光纖雷射器會產生圓形射束截面 並且藉由一掃描器單元在該基板表面上被引導’該光纖雷 射器發射的光具有的波長係750 nm至3000 nm。S -10 - 201137952, a plurality of selective emitter fingers can be written on a solar substrate by means of such a separate beam. In this case, the beam splitter is preferably structurally adapted to the configuration of the finger regions. The contact electrodes of a solar cell include, in addition to the finger regions, a main line, a so-called "bus bar" on which variations of the individual finger regions are collected. The selective emitters of the solar cells are formed both in the regions of the individual finger regions and in the regions of the "bus bars". In this case, the laser doping process is subdivided into a plurality of working steps for writing the individual finger regions and the "bus bar". The doping depth can be varied during the laser doping process, which can be used, for example, to form deeper doping in individual working steps in the production of a selective emitter. Another advantageous variation of the present invention In the body, the scanner unit has at least one fast scanner, which may be, for example, a galvo-scanner, a polygon scanner and/or a resonance scanner. Such a fast scanner enables a sufficiently high processing speed on a large area substrate that meets production requirements. These scanner components can be selected based on the lasers used and the projected beam movement. Guidance on the currently available travel speeds, using a pulsed laser with a repetition rate of 1 MHz, 20 m/s, using a continuous laser system of 400 m/s. In a suitable embodiment for doping a substrate, the scanner unit has a scanning range that extends over at least two substrates. If a relatively small substrate, such as a wafer, is processed in the device, and for example a 7 x 8 wafer is processed on a substrate holder, this is particularly suitable when the scanner unit has the same scanning range as the substrate holder. Because in this case every -11 - 201137952 devices only have to combine a fiber laser and a scanner unit. However, the processing range can also be divided between two or more laser beams, and then each of the laser beams has a scan range smaller than that of the substrate holder. In a development, the device according to the invention has at least one positioning device for causing the substrates to be within the scanning range of the laser and/or at least one monitoring device for the substrates. If the substrates are intended to be processed not only over the entire area but also to undergo a specific treatment in a locally defined manner, then it is necessary that the substrates are accurately positioned relative to the scanner unit. In order to ensure such a high positioning accuracy in the laser doping device, a positioning device known in the prior art can be integrated into the laser doping module, or the positioning device can be arranged in the transport direction. Upstream of the laser doping module, in which case a transport system with precise substrate position transfer must be used. Moreover, in a suitable development, a monitoring device for the completed doping can be provided. The monitoring device may be a measuring device for optical or electrical surface characterization known from the prior art. Accurate substrate position transfer is again necessary to correctly distribute the measurement flaws in its position. Furthermore, the stated object is achieved by a method for doping a substrate, wherein at least one dopant and the substrate The surface is in contact and the surface of the substrate is locally heated by a laser beam. In this case 'using a fiber laser', the fiber laser produces a circular beam cross section and is guided on the surface of the substrate by a scanner unit. The light emitted by the fiber laser has The wavelength range is from 750 nm to 3000 nm.
S -12- 201137952 實現所描述方法的一前提係近年來雷射技術經歷了迅 速發展’這除其他之外已經導致了高功率的並且有成本效 益的光纖雷射器。導致實現了技術上起作用且經濟上實用 的雷射摻雜方法的多個必要特徵係光纖雷射器的低價格、 在射束截面上具有高斯功率密度分佈的良好的射束品質、 圓形的射束截面以及允許對基板表面進行掃描的高度發展 的掃描器單元。 在根據本發明的方法中，該光纖雷射器發射的光具有 的波長係75〇 nm至3000 nm。在這個波長範圍內，矽對於 低功率的光係透明的。然而在高功率密度的情況下，例如 在一光纖雷射器的射束中發生的，該基板表面被迅速加熱 並且該等光學特性被改變。由此光進入矽中的穿透深度被 降低到1 μπι的數量級。這個精確的穿透深度甚至可以藉由 選擇處理參數來設定。 然而原則上還可以設想使用發射的光具有5 00 nm至 〇 600 nm波長的光纖雷射器。此種方法主要在希望雷射進入 基板中的小的穿透深度或小的摻雜深度時被使用。 當進行根據本發明的雷射摻雜方法時，已證明使用連 續運作的連續波雷射器或具有在80 ns至10 範圍內相對 長的脈衝長度的脈衝雷射器係適宜的。使用該等長脈衝帶 來了溫度作用在基板表面上的較長時間，因此該基板表面 不是必須被熔化或僅僅必須在小程度上被熔化，並且因此 在摻雜後不會記錄基板表面上的晶體損傷。儘管用於雷射 摻雜方法的溫度較低，但藉由較長時間的溫度作用實現了 -13- 201137952 足夠的摻雜劑引入。 在根據本發明的方法的一適宜的實施例中，脈衝雷射 器的脈衝形狀被形成爲使得它在一時間功率圖中具有大致 矩形的形狀，該形狀具有至少一個短的上升時間以及在8 0 ns至10卜8範圍內的脈衝長度並且沒有明顯的功率尖峰。與 其他脈衝雷射器（其中可得的功率集中在非常短的功率尖 峰上）相比，一光纖雷射器使之有可能產生具有均勻脈衝 功率的非常長的脈衝。該等長脈衝使能得到溫和的基板處 理，這甚至在基板被熔化時都產生極小的晶體損傷並且因 此產生了高性能的太陽能電池。對於該等基板的迅速處理 ，如果前導的脈衝邊緣係陡峭的，也就是說快速達到了該 雷射器的脈衝功率的話則是適宜的。藉由對比，可以使得 下降緣更淺以便增加溫度的作用時間並且使能以更低的應 力來更慢地再結晶。 在根據本發明的方法的一有利的變體中，所採用的步 驟係使得該基板表面僅在其物質的固態得以維持的程度上 被加熱。在這種情況下’根據本發明的雷射摻雜在較低的 溫度下、也就是說在基板的熔點以下完成，並且作爲回報 使用較長的摻雜時間；這使能非常溫和地處理該等基板。 由於避免了熔化和再結晶’所以完全避免了與再結晶有關 的缺陷機理。對於爲增大光敏度其表面被結構化的太陽能 電池基板的處理’同樣必要的是使用完全保留且不熔化所 產生的表面結構的摻雜方法。 在根據本發明的方法的一適宜的實施例中，該方法被 -14- 201137952 用於基板的全面積摻雜。藉助該連續波雷射器或以長脈衝 進行脈動的光纖雷射器進行的溫和的基板處理既在技術上 也在經濟上允許了對大的基板面積的摻雜，例如像太陽能 電池上的光學活性區。 在根據本發明的方法的一有利的發展中，並非基板表 面所有的區域都相同地進行處理，而是對限定的基板區域 進行更大程度的熱載入並且更重地摻雜。用於實現更重的 〇 摻雜的一重要方法參數係該掃描器移動的降低的速度。然 而作爲它的或支持它的一替代方案，還有可能改變該雷射 摻雜方法的其他參數。 在根據本發明的方法的一可能的變體中，所採用的步 驟係使得該基板表面被局部熔化。如果該等基板的表面形 態不是必須進行保留，則伴隨基板表面的熔化以及再結晶 的一雷射摻雜也是有可能的。藉助於表面處的更高溫度以 及物質的液態，有可能產生非常高的摻雜。當使用非常高 〇 的能量密度時，還有可能打開存在於基板上的多個絕緣層 ，如果有必要除去它們、或完成進入基板熔體中的向內擴 散的話。可以使用根據本發明的方法變體，例如一起使用 已經存在了發射極摻雜和減反射塗層的太陽能電池基板， 來打開在隨後的接觸製造的區域中的減反射塗層並且同時 在該等選擇性發射極區域中進行更高的摻雜。由於在該方 法中，僅提供給該等觸點的表面區域係導電的’因此該等 觸點的特別簡單的、自對齊的電極沉積係有可能的。 在根據本發明的方法的另外一示例性實施例中’處理 -15- 201137952 速度由於以下事實而增大：多個雷射器同時照射該基板表 面的不同空間區域並且藉助這種平行處理實現了處理速度 的倍增。 在根據本發明的雷射摻雜方法的一具體變體中，雷射 束藉由一分束器被分離成多個部分雷射束。此種方法主要 在意欲僅對局部區域而非整個基板進行處理時是引起興趣 的。作爲舉例’如果旨在於一太陽能電池基板上寫下一選 擇性發射極的50至400指狀區結構時，可以使用此種方法 。在該摻雜方法中，該雷射束可以藉由一用於全像射束分 離成50至40 0個部分雷射束的繞射元件進行分離，該等部 分雷射束然後可以同時刻寫該選擇性發射極的50至400個 指狀區線條。 在根據本發明的方法的一適宜的示例性實施例中，該 掃描器單元遍及至少兩個基板在至少一個空間方向上移動 該雷射束。當使用根據本發明的雷射摻雜方法時，經常存 在在一雷射器的掃描方向上串聯配置多個基板的情況。由 於事實上雷射束在多個基板上同樣地移動，使得該方法特 別簡單。取決於該裝置的實施例，有可能在一或兩個空間 方向上完成雷射束在多個基板上的移動。 根據本發明的一有利的發展，將該基板在摻雜過程中 藉由一支架進行保持或運輸，其中該支架具有一在該基板 方向上反射該雷射束的表面。也就是說，該支架具有一將 已經穿透該基板的雷射束反射回去的鏡反射表面。在這種 情況下，被反射的雷射束可以被再次使用來加熱該基板的 -16- 201137952 表面並且因此使能改善摻雜劑進入基板中的向內擴散。 在這種情況下，可以在該基板的正面以及該基板的背 面均提供一摻雜層，藉由該摻雜層多種摻雜劑可以穿透進 入該基板中。 【實施方式】 圖1示意性地示出了根據本發明的一雷射摻雜裝置的 0 一可能的示例性實施例。在圖1中展示的雷射摻雜裝置的 該等單個元件僅展示了其功能原理並且因此不是以真實按 比例的方式描繪且亦非在每個細節上都以精確的方式描繪 :該圖中該等元件的配置僅是出於能更好說明的目的。它 並不反映在該雷射摻雜裝置中該等元件的具體配置。一光 纖雷射器1發射一雷射束2，該雷射束由一掃描器單元3引 導在一基板8的基板表面4上的一限定路徑D上。現在對該 雷射摻雜裝置的各別部件在下面進行說明。 〇 該雷射摻雜裝置具有至少一光纖雷射器1，它在所示 圖中係一高功率雷射器，其功率高到足以在可接受的時間 內處理基板8。在圖1的示例性實施例中使用的光纖雷射器 1的波長係在近紅外的光譜範圍內、在7 5 0 nm和3 μιη之間 的波長範圍內。光纖雷射器1的波長範圍和功率決定了雷 射束2進入基板8中的穿透深度。在一矽基板的情況下，雷 射束2的穿透深度較佳地被設定在1 1〇 μιη之間的—適 宜的深度範圍。 確切使用的光纖雷射器1或確切使用的它的波長取決 -17- 201137952 於基板8的類型以及所希望的穿透深度。因此’對於在矽 或其他基板材料中的淺摻雜也可以採用短於nm的波長 。所使用的雷射器波長的選擇還取決於該光纖雷射器的可 商購性。目前，除了在近紅外範圍內操作的光纖雷射器之 外，從藉由倍頻由紅外光產生在500 nm至600 nm光譜範圍 內的綠光的光纖雷射器是可得的。該等短波雷射器在其中 希望小的摻雜深度的實施例中係較佳的。 取決於雷射器的另外的發展以及新的基板或除摻雜矽 太陽能電池發射極之外的其他應用，然而根據本發明還有 可能使用在具有150 nm波長的紫外光與具有11 μηι波長的 紅外光之間的其他的波長範圍。 對於太陽能電池基板的雷射摻雜的應用，已經證明適 宜的是在較長的時間內將熱預算引入基板8中。旨在使該 基板表面4被該雷射處理盡可能少地熔化以避免位錯。因 此，在圖1中使用的光纖雷射器1係一連續操作的雷射器， 即一CW雷射器。在另一實施例（未示出）中，光纖雷射 器1係具有在80 ns和10 |as之間的較長脈衝長度的一脈衝雷 射器。當使用脈衝雷射器時，摻雜特性輪廓可以另外藉由 脈衝形狀而設定。在脈衝開始處具有陡峭邊緣的矩形脈衝 已證明是特別適宜的。然而，脈衝形狀是必須考慮到並且 與另外的參數一起設定的僅僅一參數。因此，雷射器功率 、射束直徑、射束品質、射束截面中的強度分佈、雷射束 的相對移動速度、脈衝與脈衝的重疊、線重疊、基板材料 、後者的質地、結晶度以及品質、使用的摻雜劑、環境溫S -12- 201137952 A prerequisite for the implementation of the described method is that laser technology has experienced rapid development in recent years. This has led, among other things, to high-power and cost-effective fiber lasers. A number of essential features that result in a technically functional and economically practical laser doping method are the low price of the fiber laser, good beam quality with a Gaussian power density distribution across the beam cross section, and a circular shape. The beam profile and a highly developed scanner unit that allows scanning of the substrate surface. In the method according to the invention, the light emitted by the fiber laser has a wavelength in the range of 75 〇 nm to 3000 nm. In this wavelength range, 矽 is transparent to low power light systems. However, in the case of high power density, such as occurs in the beam of a fiber laser, the surface of the substrate is rapidly heated and the optical characteristics are altered. The penetration depth of the light entering the crucible is thus reduced to the order of 1 μm. This precise penetration depth can even be set by selecting processing parameters. In principle, however, it is also conceivable to use a fiber laser having an emitted light having a wavelength of 500 nm to 〇 600 nm. This method is primarily used when it is desired to have a small penetration depth or a small doping depth into the substrate. When carrying out the laser doping method according to the present invention, it has proven to be suitable to use a continuously operating continuous wave laser or a pulsed laser having a relatively long pulse length in the range of 80 ns to 10. The use of the equal length pulse causes a temperature to act on the surface of the substrate for a long time, so that the surface of the substrate does not have to be melted or only has to be melted to a small extent, and therefore does not record on the surface of the substrate after doping. Crystal damage. Although the temperature used for the laser doping method is low, sufficient dopant introduction is achieved by the action of a longer time temperature -13-201137952. In a suitable embodiment of the method according to the invention, the pulse shape of the pulsed laser is formed such that it has a substantially rectangular shape in a time power diagram, the shape having at least one short rise time and at 8 Pulse lengths in the range of 0 ns to 10 dB and no significant power spikes. Compared to other pulsed lasers, where the available power is concentrated on very short power spikes, a fiber laser makes it possible to produce very long pulses with uniform pulse power. This isometric pulse enables gentle substrate processing, which produces minimal crystal damage even when the substrate is melted and thus produces a high performance solar cell. For the rapid processing of such substrates, it is suitable if the leading edge of the pulse is steep, i.e., the pulse power of the laser is quickly reached. By contrast, the falling edge can be made shallower to increase the duration of action of the temperature and to enable slower recrystallization with lower stress. In an advantageous variant of the method according to the invention, the step employed is such that the surface of the substrate is heated only to the extent that the solid state of its substance is maintained. In this case, the laser doping according to the invention is carried out at a lower temperature, that is to say below the melting point of the substrate, and a longer doping time is used in return; this enables very gentle processing of the Such as the substrate. Since the melting and recrystallization are avoided, the defect mechanism associated with recrystallization is completely avoided. For the treatment of a solar cell substrate whose surface is structured to increase the photosensitivity, it is also necessary to use a doping method which completely retains and does not melt the surface structure produced. In a suitable embodiment of the method according to the invention, the method is used for full-area doping of the substrate by -14-201137952. The gentle substrate treatment by means of the continuous wave laser or a fiber laser pulsating with long pulses both technically and economically allows for doping of large substrate areas, such as for example on solar cells. Active zone. In an advantageous development of the method according to the invention, not all of the areas of the substrate surface are treated identically, but rather a greater degree of heat loading and more doping of the defined substrate areas. An important method parameter for achieving heavier erbium doping is the reduced speed of the scanner movement. However, as an alternative to it or to support it, it is also possible to change other parameters of the laser doping method. In a possible variant of the method according to the invention, the step employed is such that the surface of the substrate is locally melted. If the surface morphology of the substrates does not have to be preserved, a laser doping accompanying melting and recrystallization of the substrate surface is also possible. By means of the higher temperature at the surface and the liquid state of the substance, it is possible to produce very high doping. When very high energy densities are used, it is also possible to open a plurality of insulating layers present on the substrate, if necessary to remove them, or to complete the inward diffusion into the substrate melt. The method variant according to the invention can be used, for example using a solar cell substrate in which an emitter doping and an anti-reflection coating are already present, to open the anti-reflective coating in the area of subsequent contact fabrication and at the same time Higher doping is carried out in the selective emitter region. Since in this method only the surface areas provided to the contacts are electrically conductive, a particularly simple, self-aligned electrode deposition of such contacts is possible. In a further exemplary embodiment of the method according to the invention, the 'Process -15-201137952 speed is increased by the fact that a plurality of lasers simultaneously illuminate different spatial regions of the substrate surface and with this parallel processing The processing speed is doubled. In a particular variation of the laser doping method according to the invention, the laser beam is separated into a plurality of partial laser beams by a beam splitter. This approach is of interest primarily when it is intended to treat only local areas rather than the entire substrate. By way of example, this method can be used if a 50 to 400 finger structure is intended to be written on a solar cell substrate with a selective emitter. In the doping method, the laser beam can be separated by a diffractive element for separating the holographic beam into 50 to 40 partial laser beams, which can then be simultaneously written. 50 to 400 finger line lines of the selective emitter. In a suitable exemplary embodiment of the method according to the invention, the scanner unit moves the laser beam in at least one spatial direction over at least two substrates. When the laser doping method according to the present invention is used, there are often cases where a plurality of substrates are arranged in series in the scanning direction of a laser. This method is particularly simple due to the fact that the laser beam moves equally over a plurality of substrates. Depending on the embodiment of the device, it is possible to complete the movement of the laser beam over a plurality of substrates in one or two spatial directions. According to an advantageous development of the invention, the substrate is held or transported during the doping process by a holder having a surface which reflects the laser beam in the direction of the substrate. That is, the holder has a mirror reflective surface that reflects the laser beam that has penetrated the substrate back. In this case, the reflected laser beam can be reused to heat the -16-201137952 surface of the substrate and thus enable improved inward diffusion of dopant into the substrate. In this case, a doped layer may be provided on both the front side of the substrate and the back side of the substrate, through which a plurality of dopants of the doped layer may penetrate into the substrate. [Embodiment] Fig. 1 schematically shows a possible exemplary embodiment of a laser doping apparatus according to the present invention. The individual elements of the laser doping device shown in Figure 1 only show their functional principle and are therefore not depicted in a true scaled manner and are not depicted in a precise manner in every detail: in the figure The configuration of these components is for the purpose of better illustration. It does not reflect the specific configuration of the components in the laser doping device. A fiber laser 1 emits a laser beam 2 which is guided by a scanner unit 3 on a defined path D on the substrate surface 4 of a substrate 8. The individual components of the laser doping device will now be described below. 〇 The laser doping device has at least one fiber laser 1 which is shown in the drawing as a high power laser having a power high enough to process the substrate 8 in an acceptable time. The wavelength of the fiber laser 1 used in the exemplary embodiment of Fig. 1 is in the near-infrared spectral range, in the wavelength range between 75 nm and 3 μm. The wavelength range and power of the fiber laser 1 determines the penetration depth of the laser beam 2 into the substrate 8. In the case of a substrate, the penetration depth of the laser beam 2 is preferably set to a suitable depth range between 1 1 〇 μηη. The exact wavelength of the fiber laser 1 used or its exact wavelength depends on the type of substrate 8 and the desired penetration depth. Thus, wavelengths shorter than nm can also be used for shallow doping in germanium or other substrate materials. The choice of laser wavelength to use also depends on the commercial availability of the fiber laser. Currently, in addition to fiber lasers operating in the near-infrared range, fiber lasers are available from green light that produces a green light in the 500 nm to 600 nm spectral range by frequency doubling. Such short-wave lasers are preferred in embodiments in which a small doping depth is desired. Depending on the further development of the laser and the new substrate or other applications other than the doped 矽 solar cell emitter, it is also possible according to the invention to use ultraviolet light having a wavelength of 150 nm and having a wavelength of 11 μη Other wavelength ranges between infrared light. For the application of laser doping of solar cell substrates, it has proven to be expedient to introduce a thermal budget into the substrate 8 over a longer period of time. It is intended that the substrate surface 4 is melted as little as possible by the laser treatment to avoid dislocations. Therefore, the fiber laser 1 used in Fig. 1 is a continuously operated laser, i.e., a CW laser. In another embodiment (not shown), the fiber laser 1 is a pulsed laser having a longer pulse length between 80 ns and 10 | as. When a pulsed laser is used, the doping characteristic profile can be additionally set by the pulse shape. Rectangular pulses with sharp edges at the beginning of the pulse have proven to be particularly suitable. However, the pulse shape is only one parameter that must be considered and set with additional parameters. Therefore, laser power, beam diameter, beam quality, intensity distribution in the beam cross section, relative movement speed of the laser beam, overlap of pulses and pulses, line overlap, substrate material, texture of the latter, crystallinity, and Quality, dopants used, ambient temperature
S -18- 201137952 度以及一系列的其他參數起著作用。 該雷射束2具有一簡單的圓形射束截面，較佳地在該 截面上具有高斯強度分佈。這樣一射束具有以下優點：一 簡單的光學單元足夠用於射束成形，並且該射束在給定了 20 μηι與5 00 μιη之間的較佳範圍內的一焦點直徑時具有大 致1 mm的大的焦點深度。這種長的焦點範圍產生了 一強穩 的且沒有問題的方法。因此在雷射束2中可以免除一複雜 〇 的並且昂貴的自動聚焦系統。 一掃描器單元3實現了雷射束2在基板表面4上的引導 。該掃描器單元3可以包括不同的掃描器部件3a、3b，如 圖1所示。在這種情況下，總體上每個掃描器部件3 a、3 b 對於雷射束2在一空間方向上的移動負責。然而，還有可 能的是掃描器單元3具有用於在一空間方向上移動雷射束2 的僅僅一掃描器。在這種情況下（在此未示出），一基板 運輸裝置（在此未示出）提供了基板8和雷射束2之間在一 Ο 第二空間方向上的相對移動。 在圖1的展示中，該掃描器部件3 a係一多邊形掃描器 ’它繞著其轉動軸A係可轉動的並且因此可以帶來基板8上 的在X方向上的雷射束移動。將一檢流計掃描器示意性地 描繪爲掃描器部件3b。所述掃描器繞著一轉動軸B在從其 靜止位置開始的兩個方向C上係可移動的並且因此可以帶 來該基板上的在y方向上的雷射束移動。 掃描器部件3a、3b的驅動產生了雷射束2在基板表面4 上的一限定路徑D上的移動。該路徑D可以被限定爲使得 -19- 201137952 完成了均勻的基板摻雜’但它也可以被限定爲使得實現了 局部更高的摻雜。掃描器部件3a、3b的選擇取決於使用的 光纖雷射器1以及基板8上所希望的路徑。除了提及的掃描 器類型之外，還可以使用共振掃描器或其他掃描器。 在該雷射摻雜方法中，基板表面4與一摻雜劑源相接 觸，該摻雜劑源可以以物質的固態、液態或氣態存在。然 而，該等摻雜劑還能以氣溶膠的形式存在，並且結合該雷 射摻雜還可以確切地使用另外的特殊形式。因此，在雷射 束2的影響下，一液體前體可以被轉化成一蒸汽圓拱，然 後從該圓拱完成摻雜。可以使用習知技術中已知的所有化 合物作爲摻雜劑。對於矽的摻雜，它們係來自第二、第三 、第五或第六主族元素的化合物；作爲舉例經常使用硼和 磷的化合物。對於矽的摻雜，特別較佳地以磷酸用於n型 摻雜並且硼酸用於ρ型摻雜。該等摻雜劑能以習知技術中 已知的方式施用，例如液體摻雜劑藉由噴霧、輥壓或旋塗 施用。 對於液體摻雜劑的處理，用有機或無機溶劑進行稀釋 可能是適宜的；特別經常地使用水作爲一溶劑。當使用磷 酸時’例如使用0.001%和8 5%之間的濃度。特別在使用氣 態前體時’還使用了惰性或活性的稀釋或清掃氣體，例如 像惰性氣體、氮氣、氫氣或氧氣。取決於使用的摻雜劑， 可能適宜的是將該摻雜劑或基板8加熱到達2 0 0 t的溫度。 由於方法工程學原因或者由於所希望的副作用例如一蝕刻 活性’這可能是必須的。 -20- 201137952 圖2示出了根據本發明的雷射摻雜裝置的另外一實施 例。在這種情況下，與圖1中的那些相同的元件由相同的 參考符號表示。一分束器5被配置在雷射束2的路線中，所 述分束器將雷射束2分離成多個部分雷射束9。所使用的光 纖雷射器1係一非常大功率的雷射器，其功率可以在多個 部分雷射束9之間分開，然後該等部分雷射束形成一種多 束配置並且使能由於不同基板區域的同時處理而得到更快 〇 的整體處理。一種多束配置還可以藉由同時使用多個雷射 器而形成。 然而’在一特別較佳的實施例（未展示）中，該多束 配置具有一光纖雷射器1以及用於全像束分離的一繞射元 件。此種分束器使能分離成50至400個部分雷射束9。以此 方式散開的一個束9可以用在太陽能電池上，例如來生產 一選擇性發射極結構。 一選擇性發射極由該基板表面4的較高摻雜的區域組 〇 成’隨後在其上形成了多個接觸電極。這個選擇性發射極 結構如在圖2中示意性展示的包括許多薄指狀區6以及與其 垂直地配置的一些主線7，所述主線在行話中稱爲“匯流條 ”。在該雷射摻雜裝置的一適宜的實施例中，該光纖雷射 器1的雷射束2被分離，其方式爲使得該等各別的部分雷射 .束9可以用於刻寫該選擇性發射極結構的各別指狀區6。 根據本發明，一選擇性發射極結構可以在一種一般摻 雜裝置中進行生產，該裝置進行了一面積基本摻雜以及局 部選擇性發射極摻雜兩者的形成。然而，還有可能構建專 -21 - 201137952 門的裝置，它們或者是僅對於形成面積基本摻雜或者是僅 對於形成局部的或選擇性的摻雜而被專門化。用於生產一 選擇性發射極結構的特殊裝置還可以與一習知的加熱爐摻 雜方法相結合。在這種情況下，所使用的摻雜劑源還可以 是一高度摻雜的表面層，例如像所謂的“死層”，它在加熱 爐摻雜之後作爲一不希望的層存在。 藉由根據本發明的雷射摻雜方法生產的選擇性發射極 結構因特別適宜的特性而突出。已經提及了可以藉由根據 本發明的雷射摻雜法生產的更高的摻雜深度。由一深的且 均勻摻雜的發射極產生的另外一肯定特徵係對抗接觸材料 (例如像銅）擴散進入基板材料中的一更好的阻擋作用。 在根據本發明的雷射摻雜方法中生產的選擇性發射極結構 的要強調的另外一特性係該等更高摻雜的區域相對於相鄰 區域的尖的橫向界限。此外，相鄰區域由於選擇性發射極 摻雜的結果而不會遭受任何損害。使用根據本發明的雷射 摻雜方法，有可能實現表面區域中的大於1 020 at/cm3的摻 雜劑濃度以及< 2 0 Ω / s q的低的薄層電阻。 圖3示意性地示出了根據本發明的光纖雷射器的一較 佳的基本上矩形的脈衝形狀。該光纖雷射器的光束在一段 上升時間（與脈衝長度相比是短的）之後迅速達到了其最 大功率。因此實現了快速的基板加熱。然後將該高功率保 持一段比較長的時間，該時間可以是在8 0 n s和1 〇 μ s之間 。在這種情況下’該雷射脈衝沒有明顯的功率尖峰’甚至 在雷射脈衝開始時也沒有。在較長一段時間內的能量輸入 Θ -22- 201137952 • 產生了摻雜劑的良好的向內擴散以及溫和的基板處理。原 則上，在此有可能的是可以發生基板表面4的至少部分的 熔化。然而，在根據本發明的一較佳的示例性實施例中， 該基板表面4僅在使得其物質的固態得以維持的程度被光 纖雷射器1加熱。因此，可以避免不希望的熔化以及再結 晶作用並且儘管如此可以達到非常好的摻雜結果。 圖4示出了 一可能的線上裝置的一段截取，該裝置具 〇 有處於雷射摻雜模組形式的根據本發明的一雷射摻雜裝置 作爲一部件。該線上裝置具有另外的部件，例如像閘室； 但另外的部件沒有示出。該雷射摻雜裝置1 0包括處理室1 1 以及處理室1 1外部的多個部件。一光纖雷射器1產生了一 雷射束2，該雷射束穿過一視窗12輻射進入處理室11中。 在所展示的示例性實施例中，該雷射摻雜裝置1 0僅具有一 掃描器，它確切地是多邊形掃描器3a。該掃描器可以在一 空間方向上移動該雷射束2;爲了將面積基板表面4上的雷 〇 射處理的位置設定在一第二空間方向上，在所示出的示例 性實施例中用基板運輸裝置15移動該基板。在雷射摻雜模 組的其他實施例（未示出）中，使用了不連續的運輸裝置 以及二維的掃描器單元。此外該雷射慘雜裝置包括：一介 質供應源1 3 ’它能以受監測的方式提供液態和氣態的介質 ;以及一介質處置單元14’它用來將用過的液體、氣體以 及輔助氣體帶走。 圖5爲補充之前該等圖而示意性地展示了以下事實： 掃描器單元3可以在多個基板8上的一路徑E上移動雷射束2 -23- 201137952 。在所示出的這個實例中’該雷射束2在y方向上被移動。 圖中並沒有展示爲了對基板8上在第二空間方向\上的雷射 路徑進行控制的移動裝置。對於這種移動，可以移動該射 束或該晶片或者移動該晶片以及射束兩者。 圖6示意性地描繪了根據本發明的雷射摻雜裝置的另 外一可能的實施例以及用於雷射摻雜的一方法順序。在第 一步驟中，藉助一運輸系統15將一或多個基板8在運輸方 向T上移動到該裝置中，該運輸系統可以是例如一皮帶運 輸系統、一氣墊運輸系統或一行進式卡盤運輸系統。在第 —方法步驟E中’施加一摻雜劑，該摻雜劑可以例如是一 液體’它藉助例如一噴霧或輥壓技術被施用在基板8上。 在下一方法步驟F中，將基板8進一步運輸到遠至一位置識 別系統17’在這裡基板8被一卡盤16接收，精確的基板位 置被識別並且卡盤1 6上的基板8隨後以高的空間位置精確 度被運輸進以上示例性實施例中說明的光纖雷射器的掃描 範圍內。在下一方法步驟G中，藉助該光纖雷射器的雷射 束2 (在此示意性地示出）完成基板8的雷射摻雜，由於該 高的定位精確度該等基板8的局部限定的摻雜也是有可能 的。在另外一方法步驟Η中，該等基板8進一步以同樣高的 定位精確度被運輸至一監測裝置1 8下面，在這裡可以監測 雷射摻雜的結果。在已經進行監測之後，基板8進一步藉 助一通常的運輸系統1 5進行運輸。在下一方法步驟Κ中， 將基板8藉由例如施用清掃液體進行清潔。 圖7示意性地示出了用於摻雜基板8的根據本發明的方S -18- 201137952 degrees and a series of other parameters play a role. The laser beam 2 has a simple circular beam cross section, preferably having a Gaussian intensity distribution in the cross section. Such a beam has the advantage that a simple optical unit is sufficient for beam shaping and that the beam has a diameter of approximately 1 mm given a focal diameter within a preferred range between 20 μm and 500 μηη. The depth of the big focus. This long focus range produces a strong and problem-free approach. Therefore, a complicated and expensive autofocus system can be dispensed with in the laser beam 2. A scanner unit 3 enables the guidance of the laser beam 2 on the substrate surface 4. The scanner unit 3 can include different scanner components 3a, 3b as shown in FIG. In this case, in general each scanner component 3a, 3b is responsible for the movement of the laser beam 2 in a spatial direction. However, it is also possible that the scanner unit 3 has only one scanner for moving the laser beam 2 in a spatial direction. In this case (not shown here), a substrate transport device (not shown here) provides relative movement between the substrate 8 and the laser beam 2 in a second spatial direction. In the illustration of Fig. 1, the scanner member 3a is a polygonal scanner which is rotatable about its axis of rotation A and thus can bring about beam movement in the X direction on the substrate 8. A galvanometer scanner is schematically depicted as scanner component 3b. The scanner is movable about a rotational axis B in two directions C from its rest position and thus can bring the laser beam movement in the y direction on the substrate. The driving of the scanner components 3a, 3b produces a movement of the laser beam 2 over a defined path D on the substrate surface 4. This path D can be defined such that -19-201137952 accomplishes uniform substrate doping' but it can also be defined such that locally higher doping is achieved. The choice of scanner components 3a, 3b depends on the fiber laser 1 used and the desired path on the substrate 8. In addition to the type of scanner mentioned, a resonant scanner or other scanner can be used. In the laser doping method, the substrate surface 4 is in contact with a dopant source which may be present in a solid, liquid or gaseous state of the substance. However, the dopants can also be present in the form of an aerosol, and in combination with the laser doping it is also possible to use other special forms. Thus, under the influence of the laser beam 2, a liquid precursor can be converted into a vapor dome and then doped from the dome. All of the compounds known in the prior art can be used as dopants. For the doping of cerium, they are compounds derived from the elements of the second, third, fifth or sixth main group; compounds which often use boron and phosphorus are exemplified. For doping of germanium, it is particularly preferred to use phosphoric acid for n-type doping and boric acid for p-type doping. The dopants can be applied in a manner known in the art, for example by applying a liquid dopant by spraying, rolling or spin coating. For the treatment of liquid dopants, it may be suitable to dilute with an organic or inorganic solvent; water is often used as a solvent. When phosphoric acid is used, for example, a concentration between 0.001% and 85% is used. Especially when using gaseous precursors, inert or reactive dilution or sweeping gases are used, such as, for example, inert gases, nitrogen, hydrogen or oxygen. Depending on the dopant used, it may be desirable to heat the dopant or substrate 8 to a temperature of 200 Torr. This may be necessary for methodological reasons or due to desirable side effects such as an etch activity. -20- 201137952 Figure 2 shows another embodiment of a laser doping apparatus in accordance with the present invention. In this case, the same elements as those in Fig. 1 are denoted by the same reference symbols. A beam splitter 5 is arranged in the course of the laser beam 2, which splits the laser beam 2 into a plurality of partial laser beams 9. The fiber laser 1 used is a very high power laser whose power can be split between a plurality of partial laser beams 9, and then the partial laser beams form a multi-beam configuration and enable Simultaneous processing of the substrate regions results in a faster overall processing. A multi-beam configuration can also be formed by using multiple lasers simultaneously. However, in a particularly preferred embodiment (not shown), the multi-beam configuration has a fiber laser 1 and a diffractive element for holographic beam separation. This beam splitter enables separation into 50 to 400 partial laser beams 9. A bundle 9 dispersed in this manner can be used on a solar cell, for example to produce a selective emitter structure. A selective emitter is formed by a group of higher doped regions of the substrate surface 4 and subsequently a plurality of contact electrodes are formed thereon. This selective emitter structure, as schematically illustrated in Figure 2, includes a plurality of thin finger regions 6 and a number of main lines 7 disposed perpendicular thereto, said main lines being referred to as "bus bars" in the jargon. In a suitable embodiment of the laser doping device, the laser beam 2 of the fiber laser 1 is separated by means of the respective partial lasers. The beam 9 can be used to write the selection. Individual finger regions 6 of the emitter structure. In accordance with the present invention, a selective emitter structure can be fabricated in a general doped device that performs both one-area basic doping and local selective emitter doping. However, it is also possible to construct devices for the gates that are either exclusively doped for the formation area or only for the formation of local or selective doping. A special device for producing a selective emitter structure can also be combined with a conventional furnace doping method. In this case, the dopant source used may also be a highly doped surface layer, such as, for example, a so-called "dead layer" which exists as an undesired layer after doping in the furnace. The selective emitter structure produced by the laser doping method according to the present invention is distinguished by particularly suitable characteristics. A higher doping depth which can be produced by the laser doping method according to the invention has already been mentioned. Another positive feature created by a deep and uniformly doped emitter is a better barrier against the diffusion of contact material (e.g., copper) into the substrate material. Another characteristic to be emphasized of the selective emitter structure produced in the laser doping method according to the present invention is the sharp lateral limit of the higher doped regions relative to the adjacent regions. In addition, adjacent regions do not suffer any damage as a result of selective emitter doping. With the laser doping method according to the present invention, it is possible to achieve a dopant concentration of more than 1 020 at/cm 3 in the surface region and a low sheet resistance of < 2 0 Ω / s q . Figure 3 is a schematic illustration of a preferred substantially rectangular pulse shape of a fiber optic laser in accordance with the present invention. The fiber laser's beam quickly reaches its maximum power after a rise time (short compared to the pulse length). Therefore, rapid substrate heating is achieved. This high power is then held for a relatively long period of time, which can be between 80 n s and 1 〇 μ s. In this case 'the laser pulse has no significant power spikes' even at the beginning of the laser pulse. Energy input over a longer period of time Θ -22- 201137952 • Good inward diffusion of dopants and gentle substrate processing. In principle, it is possible here that at least partial melting of the substrate surface 4 can take place. However, in a preferred exemplary embodiment in accordance with the present invention, the substrate surface 4 is heated by the fiber laser 1 only to such an extent that the solid state of its substance is maintained. As a result, undesired melting and recrystallization can be avoided and nevertheless very good doping results can be achieved. Figure 4 shows a section of a possible in-line device having a laser doping device in accordance with the present invention in the form of a laser doping module as a component. The inline device has additional components, such as a lock chamber; however, additional components are not shown. The laser doping device 10 includes a plurality of components outside the processing chamber 1 1 and the processing chamber 11. A fiber laser 1 produces a laser beam 2 that is radiated through a window 12 into the processing chamber 11. In the exemplary embodiment shown, the laser doping device 10 has only one scanner, which is exactly the polygon scanner 3a. The scanner can move the laser beam 2 in a spatial direction; in order to set the position of the lightning beam processing on the area substrate surface 4 in a second spatial direction, in the exemplary embodiment shown The substrate transport device 15 moves the substrate. In other embodiments (not shown) of the laser doping module, a discontinuous transport device and a two-dimensional scanner unit are used. Furthermore, the laser miscellaneous device comprises: a medium supply source 1 3 'which is capable of providing liquid and gaseous medium in a monitored manner; and a medium handling unit 14' for using used liquid, gas and auxiliary gas take away. Figure 5 is a schematic illustration of the fact that the scanner unit 3 can move the laser beam 2 -23-201137952 over a path E on a plurality of substrates 8 in addition to the figures. In the illustrated example, the laser beam 2 is moved in the y-direction. The mobile device for controlling the laser path in the second spatial direction on the substrate 8 is not shown. For this movement, the beam or the wafer can be moved or both the wafer and the beam can be moved. Fig. 6 schematically depicts a further possible embodiment of a laser doping device according to the invention and a method sequence for laser doping. In a first step, one or more substrates 8 are moved into the device in a transport direction T by means of a transport system 15, which may be, for example, a belt transport system, an air cushion transport system or a traveling chuck. Transportation System. In a first method step E, a dopant is applied, which may for example be a liquid, which is applied to the substrate 8 by means of, for example, a spraying or rolling technique. In a next method step F, the substrate 8 is further transported as far as a position identification system 17' where the substrate 8 is received by a chuck 16, the exact substrate position is identified and the substrate 8 on the chuck 16 is subsequently high The spatial positional accuracy is transported into the scanning range of the fiber laser described in the above exemplary embodiment. In the next method step G, the laser doping of the substrate 8 is completed by means of the laser beam 2 (shown schematically here) of the fiber laser, which is locally limited due to the high positioning accuracy Doping is also possible. In a further method step, the substrates 8 are further transported to the underside of a monitoring device 18 with the same high positioning accuracy, where the results of the laser doping can be monitored. Subsequent to the monitoring, the substrate 8 is further transported by a conventional transport system 15. In the next method step, the substrate 8 is cleaned by, for example, application of a cleaning liquid. Figure 7 shows schematically a square according to the invention for doping a substrate 8
S -24- 201137952 • 法的一可能的應用變體。在所示出的示例性實施例中，待 摻雜的基板8分別在該基板表面4以及該基板背面24兩者上 具有一摻雜層19和20。在本發明的其他變體中，還有可能 僅在基板表面4上或僅在基板背面24上提供摻雜層19或20 。在摻雜的過程中，基板8被一支架22保持或者由支架22 運輸穿過一摻雜裝置。該支架22係例如適合於安裝或運輸 基板8的一支架或卡盤。該支架22具有一鏡反射表面23, 〇 藉助於該表面，穿過基板8碰撞在支架22上的一雷射束2作 爲一反射的雷射束2 1被反射回去穿過基板8。在該背向反 射過程中，不僅基板表面4而且還有該基板背面24都被熱 活化。這個結果導致了摻雜劑從該摻雜層1 9以及摻雜層20 中向內擴散進基板8中。因此，使用圖7中示出的方法，有 可能既在正面上又在背面上摻雜基板8。 如以上已經提及的，在該基板背面24上的摻雜層20係 任選的，即它不是必須要提供的。在圖7中示出的方法還 Ο 適合用於改進或加速基板8的基板正面的摻雜和/或用於增 大摻雜劑進入基板8中的穿透深度。 如在圖7的實例中所示的，可以任選地在該基板背面 24上的摻雜層20與該支架22之間提供一空氣間隙25。 【圖式簡單說明】 本發明在下面參照附圖進行更詳細地說明，其中 圖1基於一示意圖示出了根據本發明的一雷射摻雜裝 置的可能的基礎構造； -25- 201137952 圖2示意性地示出了根據本發明的另外一可能的實施 例，其中一雷射束藉由一分束器被分離成多個部分雷射束 t 圖3不意性地不出了 一光纖雷射器的可能的脈衝形狀 圖4示意性地描繪了根據本發明的一裝置的一可能的 實施例，係作爲一線上基板處理裝置的一部件； 圖5示意性地展示了雷射器的掃描長度可以在多個基 板上延伸； 圖6示意性地描繪了根據本發明的一裝置的另外一可 能的實施例以及用於雷射摻雜的一可能的方法順序；並且 圖7示意性地示出了用於摻雜基板的根據本發明的方 法的一應用變體。 【主要元件符號說明】 1 :光纖雷射器 2 ·雷射束 3 :掃描器單元 3 a :掃描器部件 3b :掃描器部件 4 :基板表面 5 :分束器 6 :指狀區 7 :主線 -26- 201137952 基板 部分雷射束 :雷射摻雜裝置 :處理室 :視窗 Ο :介質供應源 :介質處置單元 :運輸系統 :卡盤 :位置識別系統 :監測裝置 :摻雜層 :摻雜層 :雷射束 :支架 :表面 :基板背面 :空氣間隙 轉動軸 轉動軸 方向 路徑 E :路徑S -24- 201137952 • A possible application variant of the law. In the illustrated exemplary embodiment, the substrate 8 to be doped has a doped layer 19 and 20 on both the substrate surface 4 and the substrate back surface 24, respectively. In other variations of the invention, it is also possible to provide the doped layer 19 or 20 only on the substrate surface 4 or only on the substrate back side 24. During doping, the substrate 8 is held by a holder 22 or transported by a holder 22 through a doping device. The bracket 22 is, for example, a bracket or chuck suitable for mounting or transporting the substrate 8. The holder 22 has a mirror-reflecting surface 23 by means of which a laser beam 2 impinging on the holder 22 through the substrate 8 as a reflected laser beam 2 is reflected back through the substrate 8. In this back-reflection process, not only the substrate surface 4 but also the substrate back surface 24 are thermally activated. This result causes the dopant to diffuse inwardly into the substrate 8 from the doped layer 19 and the doped layer 20. Therefore, using the method shown in Fig. 7, it is possible to dope the substrate 8 both on the front side and on the back side. As already mentioned above, the doped layer 20 on the back side 24 of the substrate is optional, i.e. it is not necessarily provided. The method illustrated in Figure 7 is also suitable for improving or accelerating the doping of the substrate front side of the substrate 8 and/or for increasing the penetration depth of the dopant into the substrate 8. As shown in the example of FIG. 7, an air gap 25 may optionally be provided between the doped layer 20 on the backside 24 of the substrate and the bracket 22. BRIEF DESCRIPTION OF THE DRAWINGS The invention will be explained in more detail below with reference to the accompanying drawings in which FIG. 1 shows a possible basic configuration of a laser doping device according to the invention based on a schematic diagram; -25- 201137952 2 schematically shows a further possible embodiment according to the invention in which a laser beam is separated into a plurality of partial laser beams by a beam splitter. FIG. 3 is not intended to be a fiber-optic ray. Possible Pulse Shapes of the Embody Figure 4 schematically depicts a possible embodiment of a device in accordance with the present invention as part of an on-line substrate processing apparatus; Figure 5 schematically illustrates the scanning of a laser The length may extend over a plurality of substrates; Figure 6 schematically depicts a further possible embodiment of a device according to the invention and a possible method sequence for laser doping; and Figure 7 shows schematically An application variant of the method according to the invention for doping a substrate is presented. [Description of main component symbols] 1: Fiber laser 2: Laser beam 3: Scanner unit 3a: Scanner unit 3b: Scanner unit 4: Substrate surface 5: Beam splitter 6: Finger area 7: Main line -26- 201137952 Laser beam on the substrate: Laser doping device: Processing chamber: Window Ο: Media supply: Media disposal unit: Transportation system: Chuck: Position identification system: Monitoring device: Doped layer: Doped layer : Laser beam: Bracket: Surface: Back of substrate: Air gap Rotation axis Rotation axis direction path E: Path