Maslar James E, Kalanyan Berc
Material Measurement Laboratory, National Institute of Standards and Technology, 100 Bureau Drive, Gaithersburg, Maryland 20899, USA.
Appl Spectrosc. 2025 Oct;79(10):1487-1496. doi: 10.1177/00037028251325565. Epub 2025 Mar 13.
An absorption imaging technique was described for visualizing molybdenum pentachloride (MoCl) flow during an atomic layer deposition/pulsed chemical vapor deposition process. The imaging system was composed of a telecentric lens and a commercial 7.1-megapixels (MP) complementary metal oxide semiconductor (CMOS) camera. The light source was a fiber-coupled light emitting diode operating at a peak emission wavelength of 443 nm. Flow images of MoCl vapor entrained in a carrier gas were recorded at approximately 93 frames per second in a research-grade vapor deposition chamber. The utility of this technique was illustrated by comparing the MoCl flow patterns for two precursor injection conditions, conditions consisting of different argon carrier gas flow rate and chamber pressure. For a low flow rate and chamber pressure, the flow images showed a gradual expansion of the MoCl concentration front through the field of view with a relatively short MoCl residence time. These flow patterns result in a relatively uniform precursor concentration front impinging on the wafer surface with the precursor being efficiently exhausted from the chamber, making these conditions desirable for thin film deposition in this chamber. For a high carrier gas flow rate and elevated chamber pressure, the flow images showed a high gas velocity jet impinging on the wafer chuck surface and the formation of gas recirculation zones, resulting in a relatively long residence time. These flow conditions would make it difficult to reproducibly deposit uniform thin films in this chamber. This comparison demonstrated the utility of this technique for qualitative characterization of precursor flow fields with minimal data processing. However, the two-dimensional data obtained from this technique can also provide the basis for training and validating computational fluid dynamics models. Furthermore, the addition of duplicate optical systems would provide the basis for determining the three-dimensional precursor distribution through tomographic analysis.
描述了一种吸收成像技术，用于在原子层沉积/脉冲化学气相沉积过程中可视化五氯化钼（MoCl）的流动。成像系统由一个远心透镜和一台商用710万像素（MP）互补金属氧化物半导体（CMOS）相机组成。光源是一个光纤耦合发光二极管，其峰值发射波长为443 nm。在一个研究级气相沉积室中，以大约每秒93帧的速度记录了载气中夹带的MoCl蒸汽的流动图像。通过比较两种前驱体注入条件下的MoCl流动模式，说明了该技术的实用性，这两种条件包括不同的氩载气流量和腔室压力。对于低流量和腔室压力，流动图像显示MoCl浓度前沿在视场中逐渐扩展，MoCl停留时间相对较短。这些流动模式导致前驱体浓度前沿相对均匀地撞击在晶圆表面，前驱体从腔室中有效排出，使得这些条件对于该腔室中的薄膜沉积是理想的。对于高载气流量和升高的腔室压力，流动图像显示高速气流射流撞击在晶圆卡盘表面并形成气体再循环区域，导致停留时间相对较长。这些流动条件将使得在该腔室中难以可重复地沉积均匀的薄膜。这种比较证明了该技术在最少数据处理的情况下对前驱体流场进行定性表征的实用性。然而，从该技术获得的二维数据也可以为训练和验证计算流体动力学模型提供基础。此外，添加重复的光学系统将为通过断层分析确定三维前驱体分布提供基础。
