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In-Line Metrology
Published in Robert Doering, Yoshio Nishi, Handbook of Semiconductor Manufacturing Technology, 2017
The purpose of CMP is to produce a flat surface over device topology for lithographic patterning. The CMP is used in both traditional metallization and Damascene (inlaid metal) processing. In traditional metallization processes, metal is deposited, patterned, etched, and overcoated with oxide which is polished flat. In Damascene (inlaid metal) processes, oxide (or low k dielectric) is deposited, patterned, and etched, and metal fill is deposited and then polished back to oxide. The CMP must be monitored for both local flatness within a die and across the wafer. The CMP can generate some radial variation in removal across the wafer. Both traditional and Damascene process are adversely effected by this radial variation in removal rate. Over etching of contact and via structures at the edge of the wafer can result when an oxide layer over metal is over thinned toward the wafer edge. In this case, optical film thickness is used to monitor oxide CMP for traditional metallization processes to ensure that differences in thickness of the oxide layer do not result in over etching during fabrication of contact/via openings. Stylus profilometry or scanned probe microscopy are used to determine film flatness after CMP.
Copper CMP
Published in Ungyu Paik, Jea-Gun Park, Nanoparticle Engineering for Chemical-Mechanical Planarization, 2019
Although the exposed Cu can immediately react with oxygen to form an oxide film, the film is porous and not of a self-protective nature. Therefore, a capping material, such as SiN, is necessary to prevent the corrosion of Cu. Unfortunately, the Cu corrosion depends on the delay time from the CMP polish of Cu to deposition of the protective layer. On the production line, the manufacture available time and efficiency are very hard to reach these stiff conditions. Hence, the prevention of Cu corrosion becomes the major challenge in production to improve the yield. On the other hand, the grains of Cu will enlarge during subsequent thermal processing. For instance, the heating during dielectric material deposition would induce the Cu grain growth and generate the voids in Cu due to the surface area diminution of grain boundary. This will result in poor thermal stability of Cu film. In the Cu CMP process, dishing and erosion are the other problems for the Cu line thickness control. The occurrence of dishing and erosion depends on the line width and density. Besides, the CMP parameters such as polishing down force, polish head rotation speed, polish pad elastic properties, slurry flow, polish time, and so forth affect dishing and erosion. Capping with a protective layer is the plausible way to avoid the dishing and erosion phenomena so as to improve the Cu thermal stability. This section investigated the dishing and erosion phenomena of Cu in the CMP process. The tantalum nitride (TaN) capping on the top of Cu surface is proposed to protect the Cu from corrosion and oxidation. The thermal property of Cu is also examined using stress migration to evaluate its stability.
Nanosensor Laboratory
Published in Vinod Kumar Khanna, Nanosensors, 2021
Chemical mechanical polishing (CMP) is a process that is used for the planarization of semiconductor wafers. CMP takes advantages of the synergistic effect of both physical and chemical forces for polishing of wafers. Chemistry alone cannot planarize wafers because most chemical reactions are isotropic. On the other hand, mechanical grinding may achieve surface planarization, but the surface damage is very high. Therefore, wafer polishing is done by applying a load force to the back of a wafer while it rests on a pad. Both the pad and wafer are then counter rotated while a slurry containing abrasives and reactive chemicals is passed underneath.
Analysis of cavitation and shear in bellows pump: transient CFD modelling and high-speed visualization
Published in Engineering Applications of Computational Fluid Mechanics, 2023
Tianyi Ge, Liang Hu, Rui Su, Xiaodong Ruan
Pneumatic drive bellows pumps (PDBPs) are a class of reciprocating positive displacement pumps featuring flexible bellows to create expanding cavities, sucking fluids into the bellows chambers, and decreasing cavities, pressing fluids into the discharge pipes. In addition, a pair of check valves is also set for each bellows chamber to guarantee no backflow. Due to outstanding characteristics such as self-priming, contamination-free and corrosion-resistant, PDBPs are used for a wide range of applications in the semiconductor industry, which has extremely strict requirements of contamination control for working fluids transportation (Zant, 2014). PDBPs can easily handle the circulation of washing water in wet benches and feeding of chemical liquids in chemical distribution systems. Slurries, which combine a solid (abrasives) with a liquid (basic solutions with low pH levels) and are used in polishing operations such as chemical mechanical polishing (CMP), can also be circulated and transferred by PDBPs with ease owing to their excellent suction characteristics.
Evaluation of chemical mechanical planarization slurry dispersion using a combined scanning mobility particle sizer-optical particle sizer system
Published in Aerosol Science and Technology, 2023
Donggeon Kwak, Juhwan Kim, Taesung Kim
With the Fourth Industrial Revolution (Industry 4.0), various fields, such as the Internet of Things (IoT), artificial intelligence, 5 G, and big data, are developing in novel ways. Accordingly, shrinkage of semiconductors for data processing and storage is required (Ghahramani et al. 2020). Among various processes used for manufacturing semiconductors, chemical mechanical planarization (CMP) is used for the required polishing of wafer surfaces during semiconductor manufacturing, and the number of CMP processes is increasing with decreasing device sizes (Li 2007; Steigerwald, Murarka, and Gutmann 1997). Various consumables, such as the pad, conditioner, and slurry, are used in the CMP process for smooth planarization. Among them, the slurry particularly can affect the performance of the CMP process since it contains abrasives that directly contact the wafer. The slurry contains chemicals to improve process performance and nanoparticles to polish the surface. Dispersion of the CMP slurry is important for ensuring consistency of CMP performance. The dispersion stability of the slurry can be disrupted due to not only gravity, but also the interaction between additives and nanoparticles in the slurry. A slurry with disrupted dispersion stability can cause various problems, such as consistency issues and concentration change due to sedimentation and large particle formation. Therefore, precise evaluation and analysis of dispersion stability are important in slurry preparation.
Reinforcement learning for process control with application in semiconductor manufacturing
Published in IISE Transactions, 2023
Yanrong Li, Juan Du, Wei Jiang
Chemical mechanical Planarization (CMP) is a crucial process in the semiconductor manufacturing process. Virtual metrology systems are often applied in the CMP process to remove the non-planar parts of the films. To simulate the CMP process, we first accept the simulation model in Ning et al. (1996) and Chang et al. (2006), which is defined as: where is the output vector that represents the removal rate and non-uniformity, respectively. is the control vector, that denotes the platen speed, back pressure, polish head downforce, and profile, respectively. According to Ning et al. (1996), the parameter matrices in (9) are assigned as