Predicting the Material Removal Rate in Chemical Mechanical Planarization Process: A Hypergraph Neural Network-Based Approach

Material removal rate (MRR) plays a critical role in the operation of chemical mechanical planarization (CMP) process in the semiconductor industry. To date, many physics-based and data-driven approaches have been proposed to predict the MRR. Nevertheless, most of the existing methodologies neglect the potential source of its well-organized and underlying equipment structure containing interaction mechanisms among different components. To address its limitation, this paper proposes a novel hypergraph neural network-based approach for predicting the MRR in CMP. Two main scientific contributions are presented in this work: 1) establishing a generic modeling technique to construct the complex equipment knowledge graph with a hypergraph form base on the comprehensive understanding and analysis of equipment structure and mechanism, and 2) proposing a novel prediction method by combining the Recurrent Neural Network based model and the Hypergraph Neural Network to learn the complex data correlation and high-order representation base on the Spatio-temporal equipment hypergraph. To validate the proposed approach, a case study is conducted based on an open-source dataset. The experimental results prove that the proposed model can capture the hidden data correlation effectively. It is also envisioned that the proposed approach has great potentials to be applied in other similar smart manufacturing scenarios.

Electrolytically Ionized Abrasive-Free CMP (EAF-CMP) for Copper

Chemical–mechanical polishing (CMP) is a planarization process that utilizes chemical reactions and mechanical material removal using abrasive particles. With the increasing integration of semiconductor devices, the CMP process is gaining increasing importance in semiconductor manufacturing. Abrasive-free CMP (AF-CMP) uses chemical solutions that do not contain abrasive particles to reduce scratches and improve planarization capabilities. However, because AF-CMP does not use abrasive particles for mechanical material removal, the material removal rate (MRR) is lower than that of conventional CMP methods. In this study, we attempted to improve the material removal efficiency of AF-CMP using electrolytic ionization of a chemical solution (electrolytically ionized abrasive-free CMP; EAF-CMP). EAF-CMP had a higher MRR than AF-CMP, possibly due to the high chemical reactivity and mechanical material removal of the former. In EAF-CMP, the addition of hydrogen peroxide (H2O2) and citric acid increased the MRR, while the addition of benzotriazole (BTA) lowered this rate. The results highlight the need for studies on diverse chemical solutions and material removal mechanisms in the future.

In Situ Metrology for Pad Surface Monitoring in CMP Using a Common-Path Phase-Shifting Interferometry: A Feasibility Study

In the fabrication of semiconductors, chemical mechanical polishing (CMP) is an essential wafer-planarization process. For optimal CMP, it is crucial to monitor the texture of the polishing pad; this leads to homogenous planarization of wafers. Hence, we present a new interferometric approach for in situ evaluation of the CMP pad surface based on a common-path phase-shifting interferometry, with which a series of phase-modulated interference signals immune to external perturbation can be recorded. A nanoscopic surface topology can then be reconstructed to estimate surface roughness using the recorded interference images. The surface mapping performance of the proposed method was tested by retrieving a topology of a vibrating nanostructure in immersion, of which height profiles were consistent with the result from atomic force microscopy (AFM). The method was also validated by examining the surface of a used CMP pad in simulated conditions.

Microstructure analysis of polyurethane based polishing materials

This paper presents the results of porous structure analysis of polishing materials based on polyurethanes used in chemicalmechanical planarization process of IC layers.

A Directly Modulated Laterally Coupled Distributed Feedback Laser Array Based on SiO2 Planarization Process

Low-cost and high-speed single-mode semiconductor lasers are increasingly required as wide-band access fiber communication expands in recent years. Here, a high-speed laterally coupled distributed feedback (LC-DFB) laser array is achieved based on a SiO2 planarization process. The device exhibits low threshold currents of about 12 mA and high slope efficiencies over 0.26 W/A. Stable single mode operation and high-speed performance are realized with side mode suppression ratios (SMSR) over 45 dB, and 3-dBe bandwidths exceed 14 GHz for all four channels. Such a high-speed and process simple LC-DFB laser array shows great potential to the low-cost fiber communication networks.

Enhanced Virtual Metrology on Chemical Mechanical Planarization Process using an Integrated Model and Data-Driven Approach

As an essential process in semiconductor manufacturing, Chemical Mechanical Planarization has been studied in recent decades and the material removal rate has been proved to be a critical performance indicator. Comparing with after-process metrology, virtual metrology shows advantages in production time saving and quick response to the process control. This paper presents an enhanced material removal rate prediction algorithm based on an integrated model and data-driven method. The proposed approach combines the physical mechanism and the influence of nearest neighbors, and extracts relevant features. The features are then input to construct multiple regression models, which are integrated to obtain the final prognosis. This method was evaluated by the PHM 2016 Data Challenge data sets and the result obtained the best mean squared error score among competitors.

Effects of Depth of Cutting on Damage Interferences during Double Scratching on Single Crystal SiC

In this work, the damage interference during scratching of single crystal silicon carbide (SiC) by two cone-shaped diamond grits was experimentally investigated and numerically analyzed by coupling the finite element method (FEM) and smoothed particle hydrodynamics (SPH), to reveal the interference mechanisms during the micron-scale removal of SiC at variable Z-axis spacing along the depth of cutting (DOC) direction. The simulation results were well verified by the scratching experiments. The damage interference mechanism of SiC during double scratching at micron-scale was found to be closely related to the material removal modes, and can be basically divided into three stages at different DOCs: combined interference of plastic and brittle removal in the case of less than 5 µm, interference of cracks propagation when DOC was increased to 5 µm, and weakened interference stage during the fracture of SiC in the case of greater than 5 µm. Hence, DOC was found to play a determinant role in the damage interference of scratched SiC by influencing the material removal mode. When SiC was removed in a combined brittle-plastic mode, the damage interference occurred mainly along the DOC direction; when SiC was removed in a brittle manner, the interference was mainly along the width of cutting; and more importantly, once the fragment of SiC was initiated, the interference was weakened and the effect on the actual material removal depth also reduces. Results obtained in this work are believed to have essential implications for the optimization of SiC wafer planarization process that is becoming increasingly important for the fabrication of modern electronic devices.