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Introduction
Published in S. T. Lee, Polymeric Foams, 2022
In the microelectronic industry, due to the progressive decrease in minimum feature size of the semiconductor device, the demand for a high degree of planarization on the surface of the wafer becomes increasingly critical. A simple schematic of Chemical Mechanical Pad (CMP) process is shown in Figure 1.8, where open-celled microcellular elastomeric foam soaked with inorganic slurry closely contacted with the wafer and repeatedly back and forth until a precisely smooth surface is obtained [28–30]. The consumable PU foam for the pads and slurry is an important part of the expensive process costs. PU foam must be hard enough and possess right cell size to hold right amount of particle by the cell in grinding against the wafer. Yet the cell wall has to be somewhat elastic to survive after prolonged grinding operation. How to find the optimal match between foam and slurry has been a good research topic. It can be imagined that when the pair are in the nano size, the surface smoothness will be advanced which may open new opportunities. Nonetheless, variation of the foam’s elastic modulus after repeated usage is an important parameter.
Chemical-Mechanical Polishing
Published in Robert Doering, Yoshio Nishi, Handbook of Semiconductor Manufacturing Technology, 2017
Gregory B. Shinn, Vincent Korthuis, Gautum Grover, Simon Fang, Duane S. Boning
Planarization is the process by which a surface is flattened. A key requirement is an optically flat work surface on which the lapping or polishing occurs. Figure 17.1 shows schematically a measure of planarity, the step height reduction (SHR) [2]: SHR=1−tpost∕tpre where tpost is the step height after planarization and tpre is the step height before planarization. An ideal or perfect SHR of 1 results when the post-polish step height is zero. If material is removed equally from “low” or down areas and in “high” or raised areas (e.g., as in a purely chemical wet etch), then no SHR, or SHR = 0, is the result.
™ Technology and Applications
Published in Mohamed Gad-el-Hak, MEMS, 2005
Ezekiel J. J. Kruglick, Adam L. Cohen, Christopher A. Bang
Planarization may be performed using a variety of lapping, polishing or chemical-mechanical polishing plates, pads, and abrasive slurries (e.g., alumina or diamond). Parameters include pressure applied to the substrate, and rotational speed of the plate or pad. A means of end-point detection must also be provided, so that planarization can be stopped when the layer reaches the proper thickness. Depending on the materials and parameters used, surface roughness can be obtained on the order of 100 nm rms or better with very good planarity (e.g., submicron over a 100 mm wafer). Polishing, when required by some applications (e.g., optical mirrors or valve seats), can yield even smoother surfaces. Certain combinations of materials may exhibit differential planarization rates, causing one material to become recessed below the surface of the other; however, by proper selection of planarization materials and parameters, these effects are largely controllable.
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
Surface roughness modeling in chemically etched polishing of Si (100) using double disk magnetic abrasive finishing
Published in Machining Science and Technology, 2019
Kheelraj Pandey, Pulak M. Pandey
Mechanical polishing process falls in the category of secondary manufacturing process whose prime objective is to bring out the required surface integrity and surface finish in the work material. The purpose of mechanical polishing is to reduce the peaks existing in the work material and to attain the surface finish to the desired degree of accuracy. Materials with extraordinary and stringent properties are difficult to be finished by conventional machining processes. Silicon wafer, having some stringent properties falls in the category of materials which are difficult to be finished, has been polished under synergetic actions with chemical mechanical polishing (CMP). CMP is a planarization technique which works on the concept of first weakening the atomic bonds in the workpiece by the use of chemical action and thereby removing the material from the workpiece by the use of rotatory mechanical action. Zantye et al. (2004), Luo and Dornfeld (2001) and Zarudi and Han (2003) used CMP process for polishing silicon wafer to improve its planarization, material removal mechanism and the deformity caused, which were useful to evaluate the effectiveness of the CMP process.