Park Min Kyu, Song Wan Soo, Kim Min Ho, Hong Sang Jeen
Department of Electronics Engineering, Myongji University, Yongin 17058, Korea.
Materials (Basel). 2021 Feb 28;14(5):1144. doi: 10.3390/ma14051144.
The miniaturization of devices requires the introduction of a high aspect ratio through patterning in the Damascene copper interconnect process. The high aspect ratio etch process employs hardmasks, such as amorphous carbon, that can withstand high-powered plasma exposure. When an etch hardmask is removed after patterning, the properties of the underlying film can be altered by the effect of plasma exposure during the strip process. In this study, surface properties of SiOC(H) are investigated after an amorphous carbon strip with O/Ar plasma. Since the low-k film of SiOC(H) structure shows characteristics according to the Si-O internal bonding structure, the Si-O bonding ratio of the ring, network and cage structure was analyzed through Fourier-transform infrared (FT-IR) analysis to measure changes in thin film properties. X-ray photoelectron spectroscopy (XPS) was also used to add reliability to the SiOC(H) film structure. In addition, the end point of the strip process was obtained using an optical emission spectroscopy sensor and variations in thin film characteristics over the plasma exposure time were analyzed. These results revealed the structural modification of the SiCO(H) thin film in the post-etch strip of the amorphous carbon layer (ACL) hardmask.
器件的小型化要求在大马士革铜互连工艺中通过图案化引入高深宽比。高深宽比蚀刻工艺采用诸如非晶碳之类的硬掩膜,其能够承受高功率等离子体曝光。当在图案化之后去除蚀刻硬掩膜时,在剥离过程中,底层薄膜的性能会受到等离子体曝光的影响而改变。在本研究中,在使用O/Ar等离子体去除非晶碳之后,对SiOC(H)的表面性能进行了研究。由于具有SiOC(H)结构的低k薄膜根据Si-O内部键合结构呈现出不同特性,因此通过傅里叶变换红外(FT-IR)分析来测量薄膜性能的变化,进而分析环、网络和笼状结构的Si-O键合比。还使用X射线光电子能谱(XPS)来增强SiOC(H)薄膜结构的可靠性。此外,使用光发射光谱传感器获得剥离过程的终点,并分析了等离子体曝光时间内薄膜特性的变化。这些结果揭示了在非晶碳层(ACL)硬掩膜蚀刻后剥离过程中SiCO(H)薄膜的结构改性。