Chemical mechanical planarization (CMP) is an essential polishing process in semiconductor manufacturing. Advances in memory technology, including increased capacity and performance, have increased the importance of electronic packaging. In heterogeneous integration, the interposer acts as an important intermediary between the logic die and the substrate, solving numerous I/O bump problems in high-bandwidth memory (HBM) and logic chips. Traditionally, board-to-memory connections were made through wire bonding, which required additional space for wire connections and introduced latency due to extended signal transmission paths. A through-type approach has emerged as a solution that can significantly reduce waiting time and installation space by improving space efficiency and enabling vertical connections without extending wiring. Due to these new approaches, the importance of CMP is reemerging. Implementation of this important process requires precise control of the CMP dishing/protrusion of bonding surfaces. Improper selection of Cu pad dishing/protrusion can cause problems such as increased RC delay time and signal short circuit in the wiring. In this paper, we proposed a strategy to control dishing using CMP, especially for Through-glass-via (TGV).

Most of the consumables used in the CMP (Chemical Mechanical Planarization) process are discarded because it is difficult to reuse them. Slurry accounts for most of the consumables, so research is being conducted to reduce the amount of slurry used. A previous study explains that when the same amount of slurry is injected, the material removal rate is improved when the slurry is injected wide and thin instead of the tube nozzle, which is the conventional slurry injection method. However, there was no change in the injection method due to the problems of the injection method suggested in previous studies and the lack of follow-up studies. Thus, in this paper, an injection method through an ultrasonic spray nozzle is proposed to improve the problems of the injection method proposed in previous studies. Additionally, it is intended to calculate the slurry film thickness according to the spraying range and to explain the effect of the film thickness on the material removal rate.

Chemical Mechanical Planarization (CMP) is an essential process for device integration and planarization in a semiconductor manufacturing process. The most critical function in the CMP process, is to predict and cover the geometrical characteristics of various sizes and densities, of patterned wafers for local and global planarization. To achieve the wafer-level and die-level planarization, it is necessary to understand the contact mechanism between the CMP pads and the macro-scale patterns. In the macro-scale pattern, pad deformation is divided into two layers: an asperity layer and a bulk pad layer. Through bulk pad deformation, asperity contact distribution within the pattern is predicted. In this paper, the distribution of asperity contact according to the pattern geometrical characteristics was analyzed, through large-area real contact area (RCA) measurement. Bulk pad deformation was predicted by analyzing RCA distribution according to pattern geometry such as pattern size and density, pattern shape and step height according to the polishing time, and applied pressure. Additionally, through the distribution of the contact area and the number of contact points, the rounding phenomenon and planarization characteristics in the pattern CMP were predicted.

Chemical Mechanical Planarization (CMP) is an essential process for flattening the surface of the wafer to produce a fine structure. The CMP process is performed after a break-in step prior to optimizing the polishing pad. Break-in consists of the conditioning step and warming-up step. In the conditioning step, a conditioner embedded with diamonds is used to remove residues from the pad surface and manages the directionality and height deviation of asperities on the surface. The warming-up step serves to increase the temperature of the pad surface by polishing multiple wafers. The temperature in the warming-up step is raised due to friction between the wafer and pad, and the pad state is divided into a partly warmed up section, a transition section, and a fully warmed up section of the pad. In this study, as the wafer pressure increased in the warm-up stage, the time for the pad to reach the stable section was confirmed, and the break-in mechanism was analyzed in terms of surface characteristics and mechanical properties, such as surface photograph, surface roughness of the pad, and elastic modulus of pad asperities. Based on these results, the break-in mechanism that increases the material removal rate was analyzed.

Chemical Mechanical Planarization (CMP) is an indispensable process of forming multilayer integrated circuit. However, it is necessary to understand the pattern in order to achieve global planarization. Material Removal Rate (MRR) depends on the pattern density in the actual CMP process and is required to predict the MRR according to density of the pattern. Based on the Preston equation (CMP governing equation), the MRR can be expressed as a product of pressure, relative velocity, and the Preston`s coefficient. Therefore, understanding of pressure distribution acting on the patterned wafer is essential. Pressure distribution depends on contact area between pad asperity and wafer surface. In this study, pressure distribution according to contact mode between asperity and wafer surface where step height exists was analyzed, and the planarization model presented. Finally, a comparison was done between the mathematical model and the experimental data, and the planarization model was verified.

Finite element analysis of CMP process was studied to understand uneven pressure distribution between polishing pad and wafer. Since WIWNU (Within wafer non-uniformity) is mainly influenced by dynamic viscoelastic properties of CMP polishing pad, the dynamic property of the polishing pad has to be understood first for dynamic finite element analysis of the process. To measure viscoelasticity of the polishing pad, time-dependent strain data by load were obtained using a viscoelasticity measurement system capable of measuring deformation by periodic load. Primary and secondary elastic modulus and relaxation time could be achieved for the behavior of the polishing pad by load. Finite element analysis was carried out under the same conditions as viscoelastic measurement. Material properties of the polishing pad were assumed based on results of experiments. By comparing experimental results with analytical results, material properties in the analytical model were modified and FEA was carried out again. It was confirmed that the behavior of the polishing pad by load in the experiment and FEA according to modified material properties were well matched. Through this process, viscoelastic properties of polishing pad were well defined for dynamic analysis of CMP process.

Finite element analysis model was fabricated to confirm stress concentration phenomenon occurring in the wafer edge region in the CMP process, and it was confirmed if it corresponds to the measurement result of the actual pressure sensor. First, contact stress distribution at the edge of the wafer was calculated by the finite element analysis model in which material properties and boundary conditions were set up. As a result, an engineering contact stress distribution profile was obtained. Next, the pressure generated in the edge region of the wafer was measured using a pressure sensor that detects resistance change of the polymer. To compare with the result of the finite element analysis, the non-dimensional sensor signal unit was converted into the pressure unit, and correlation between the analysis and measurement results was obtained. As a result, the finite element analysis result, the actual pressure measurement, and the trend of the results were more than 90%. The results show that the finite element analysis model produced and modified in this study is consistent with the actual behavior trend of the components.