Maslar J E, Kimes W A, Sperling B A
Material Measurement Laboratory, National Institute of Standards and Technology, 100 Bureau Drive, Stop 8320, Gaithersburg, MD 20899-8320, USA.
J Nanosci Nanotechnol. 2011 Sep;11(9):8226-32. doi: 10.1166/jnn.2011.5050.
Metal alkylamide compounds, such as tetrakis(ethylmethylamido) hafnium (TEMAH), represent a technologically important class of metalorganic precursors for the deposition of metal oxides and metal nitrides via atomic layer deposition (ALD) or chemical vapor deposition. The development of in situ diagnostics for processes involving these compounds could be beneficial in, e.g., developing deposition recipes and validating equipment-scale simulations. This report describes the performance of the combination of two techniques for the simultaneous, rapid measurement of the three major gas phase species during hafnium oxide thermal ALD using TEMAH and water: TEMAH, water, and methylethyl amine (MEA), the only major reaction by-product. For measurement of TEMAH and MEA, direct absorption methods based on a broadband infrared source with different mid-IR bandpass filters and utilizing amplitude modulation and synchronous detection were developed. For the measurement of water, wavelength modulation spectroscopy utilizing a near-IR distributed feedback diode laser was used. Despite the relatively simple reactor geometry employed here (a flow tube), differences were easily observed in the time-dependent species distributions in 300 mL/min of a helium carrier gas and in 1000 mL/min of a nitrogen carrier gas. The degree of TEMAH entrainment was lower in 300 mL/min of helium compared to that in 1000 mL/min of nitrogen. The capability to obtain detailed time-dependent species concentrations during ALD could potentially allow for the selection of carrier gas composition and flow rates that would minimize parasitic wall reactions. However, when nitrogen was employed at the higher flow rates, various flow effects were observed that, if detrimental to a deposition process, would effectively limit the upper range of useful flow rates.
金属烷基酰胺化合物，如四（乙基甲基氨基）铪（TEMAH），是一类技术上重要的金属有机前驱体，用于通过原子层沉积（ALD）或化学气相沉积来沉积金属氧化物和金属氮化物。开发用于涉及这些化合物的工艺的原位诊断技术，可能有助于例如开发沉积配方和验证设备规模的模拟。本报告描述了两种技术相结合的性能，这两种技术用于在使用TEMAH和水进行氧化铪热ALD过程中同时、快速测量三种主要气相物种：TEMAH、水和甲基乙胺（MEA），MEA是唯一的主要反应副产物。对于TEMAH和MEA的测量，开发了基于宽带红外源并配备不同中红外带通滤波器、利用幅度调制和同步检测的直接吸收方法。对于水的测量，使用了利用近红外分布反馈二极管激光器的波长调制光谱法。尽管此处采用的反应器几何结构相对简单（流动管），但在300 mL/min的氦载气和1000 mL/min的氮载气中，很容易观察到随时间变化的物种分布差异。与1000 mL/min的氮气相比，300 mL/min氦气中TEMAH的夹带程度更低。在ALD过程中获取详细的随时间变化的物种浓度的能力，可能有助于选择能够使寄生壁反应最小化的载气组成和流速。然而，当以较高流速使用氮气时，观察到了各种流动效应，如果这些效应不利于沉积过程，将有效地限制有用流速的上限。
