光增强氢氟酸钝化：一个敏感的技术检测散装硅缺陷
Summary
一个RT液体表面钝化技术研究体硅缺陷的重组活性描述。对于该技术是成功的，三个关键的步骤是必需的：（ⅰ）化学清洗和硅的蚀刻，硅的（ⅱ）浸没在15％的氢氟酸和（iii）照明1分钟。
Abstract
甲过程浸入晶片在氢氟酸（HF）时，提出暂时达到表面钝化的一个非常高的水平，以测定硅晶片的体寿命（> 100微秒）。通过这种方法，需要三个关键步骤，以实现体寿命。首先，前浸渍硅晶片在HF，它们被化学清洗，并随后蚀刻25％氢氧化四甲铵。其次，经化学处理的晶片，然后放入装满HF和盐酸的混合物中的大塑料容器，然后集中于感应线圈的光导率（PC）的测量结果。第三，为了抑制表面复合，并测量体寿命，晶片被照射在0.2个太阳用于使用卤素灯1分钟，照明被关闭，和PC测量立即服用。通过此过程，体硅缺陷的特性可以精确地确定。毛皮thermore，可以预料，一个敏感的RT表面钝化技术将是必不可少的检查体硅缺陷时，他们的浓度低（<10 12 cm -3）的。
Introduction
高寿命（> 1毫秒）单晶硅正变得对高效率太阳能电池更重要。了解嵌入式杂质的复合特性一直是，而且仍然是一个重要的课题。其中最广泛使用的技术来检查生缺陷的重组活性的是由一个光电导方法1。通过这种技术，通常难以从体重组完全分开表面，从而使得难以检查生缺陷的复合特性。幸运的是，存在若干电介质膜，可以实现非常低的有效表面重组<5厘米/秒的速度（S EFF），从而有效地抑制表面复合。这些是，氮化硅（SiN X：H）2，氧化铝（Al 2 O 3）3和非晶硅 （a -Si：H）4。沉积和一个nealing这些介电膜的温度（〜400℃）被认为是足够低不永久停用的生缺陷的重组活性。这方面的例子是铁-硼5和硼氧6的缺陷。然而，近来人们发现， 在正型的Czochralski（CZ）硅空位-氧空位和磷缺陷可在温度250-350℃的7,8-完全停用。同样，在浮区（FZ）P型硅的一个缺陷被发现禁用在约250℃9。因此，如等离子体增强化学气相沉积（PECVD），原子层沉积（ALD）的常规钝化技术可能不适合用于抑制表面复合审查成年散装缺陷。此外， 有 SiN x：H和的a-Si：H膜已经显示出通过氢化10,11停用体硅缺陷。因此，研究重组活动Ø ˚F生缺陷，一个RT表面钝化技术将是理想的。湿化学表面钝化满足这一要求。
在20世纪90年代Horanyi 等人证明了在碘乙醇硅片浸没（IE）的解决方案，提供了一种装置，以钝化的硅晶片，实现小号 EFF <10厘米/秒12。在2007 Meier等人表明，碘-甲醇（IM）的解决方案可以减少表面复合至7厘米/秒13，而在2009尔斯基等人证明，5厘米小号 EFF /秒，可通过浸渍硅片达到在氢醌-甲醇（QM）解决方案14,15。尽管被IE，IM和QM解决方案实现了优异的表面钝化，它们不提供足够的表面钝化（S EFF <5厘米/秒），以测量高纯度硅晶片的体寿命。
NT“>另一种方式浸入硅晶片在HF酸以达到表面钝化的高水平。使用HF钝化硅片的概念最早是由Yablonavitch 等人介绍，在1986年，谁表现的纪录低的S EFF 0.25±0.5厘米/秒16。虽然优异的表面钝化被次比对高电阻率的晶片，我们已经发现该技术是非重复的，从而增加了一个大的不确定性的寿命测量。因此，通过一致地实现，以限制不确定性非常低的S EFF（〜1厘米/秒），我们已经开发出一种新的HF的钝化技术，其包括三个关键步骤，（ⅰ）化学清洗和硅晶片的蚀刻，（ⅱ）浸没在15％的HF溶液和（iii）照明1分钟17,18，这个过程是既简单又有效的时间相比于传统的PECVD法和ALD沉积技术上面列出。Protocol
1.实验装置找到一个合适的通风柜的测量技术，并删除任何无关的设备，以便能更好的空气流量，降低塞满。 不要在通风橱中使用比氢氟酸（HF） 以外的任何化学物质。 使用电导率计通风柜内的抽头测试去离子（DI）水的质量。确保DI水具有至多0.055μS/厘米，在20℃的温度的电导。 将少数载流子寿命测试仪到通风橱。将电缆?…
Representative Results
图1a示出的示意图和图1b示出的实验装置的照片。当硅晶片浸入HF溶液中，随后放置在寿命测试阶段和执行测量（照明之前），一个寿命曲线，它是由表面复合的限制将导致，如在图2所示的蓝色三角形。然而，当样品被照射1分钟（同时浸入HF）， 如图1，和一个测量照射后立即进行，增加的寿命会发生，如在图2中所示的?…
Discussion
成功地执行上述的体硅寿命测量技术是基于三个关键步骤，（ⅰ）化学清洗和蚀刻硅晶片，（ⅱ）浸没在15％的HF溶液和（iii）照明1分钟17， 18,19。如果没有这些措施，大部分一辈子不能有把握测量。
作为测量技术是在RT进行的，所述表面钝化质量是高度敏感的表面污染（金属，有机膜）。因此，为了有效地除去表面的污染物，将SC 1溶液时（H 2 O的：NH…
Disclosures
The authors have nothing to disclose.
Acknowledgements
This program has been supported by the Australian Government through the Australian Renewable Energy Agency (ARENA). Responsibility for the views, information or advice expressed herein is not accepted by the Australian Government.
Materials
| Hydrofluoric acid (48%) | Merck Millipore, http://www.merckmillipore.com/AU/en/product/Hydrofluoric-acid-48%25,MDA_CHEM-100334 | 1003340500 | Harmful and toxic. Any supplier could be used provided the chemical is Analytical Reagent (AR) grade. |
| Hydrochloric acid 32%, AR | ACI Labscan, http://www.rcilabscan.com/modules/productview.php?product_id=1985 | 107209 | Harmful and toxic. Any supplier could be used provided the chemical is Analytical Reagent (AR) grade. |
| Ammonia (30%) Solution AR | Chem-supply, https://www.chemsupply.com.au/aa005-500m | AA005 | Harmful and toxic. Any supplier could be used provided the chemical is Analytical Reagent (AR) grade. |
| Hydrogen Peroxide (30%) | Merck Millipore, http://www.merckmillipore.com/AU/en/product/Hydrogen-peroxide-30%25,MDA_CHEM-107209 | 1072092500 | Harmful and toxic. Any supplier could be used provided the chemical is Analytical Reagent (AR) grade. |
| Tetramethylammonium hydroxide (25% in H2O) | J.T Baker, https://us.vwr.com/store/catalog/product.jsp?product_id=4562992 | 5879-03 | Harmful and toxic. Any supplier could be used provided the chemical is Analytical Reagent (AR) grade. |
| 640 mL round plastic container | Sistema, http://sistemaplastics.com/products/klip-it-round/640ml-round | N/A | This is a good container for storing the 15% HF solution in. |
| WCT-120 lifetime tester | Sinton Instruments, http://www.sintoninstruments.com/Sinton-Instruments-WCT-120.html | N/A | |
| Dell workstation with Microsoft Office Pro, Data acquisition card and software including Sinton Software under existing license. | Sinton Instruments, http://www.sintoninstruments.com | N/A | |
| Halogen optical lamp, ELH 300W, 120V | OSRAM Sylvania, http://www.sylvania.com/en-us/products/halogen/Pages/default.aspx | 54776 | Any equivalent lamp could be used. |
| Voltage power source | Home made power supply | N/A | Any power supply could be used provided it can produce up to 90 Volts and 1-5 Amps. |
| Conductivity meter | WTW, http://www.wtw.de/uploads/media/US_L_07_Cond_038_049_I_02.pdf | LF330 |
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Cite This Article
Grant, N. E. Light Enhanced Hydrofluoric Acid Passivation: A Sensitive Technique for Detecting Bulk Silicon Defects. J. Vis. Exp. (107), e53614, doi:10.3791/53614 (2016).