High K Metal Gate Aluminum CMP Challenges and Solutions

Xu, Kun; Chen, Yufei; Iravani, Hassan; Swedek, Bogdan; Yu, May; Wang, You; Tu, Wen-Chiang; Xia, Sherry; Karuppiah, Lakshmanan

doi:10.1149/1.3489047

Cited by 11 publications

(6 citation statements)

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“…8,9 Otherwise, the control of the metal gate height uniformity and defectivity, including microscratch and corrosion defect types in Al-CMP process is quite crucial to influence the device and yield performance of HKMG structures. In spite of extensive experimental researches of Al-CMP, [8][9][10][11][12][13][14][15][16][17][18][19][20] many fundamental effects of chemical reagents on the material removal are not well understood, especially for HKMG structure which has not been formulated systematic mathematical models to adequately describe the process mechanism. Therefore, in order to obtain a good HKMG Al gate surface planarity, chemical and ECS Journal of Solid State Science and Technology, 3 (4) P60-P74 (2014) P61 physics-based model is quite helpful in providing fundamental insight on the evolution of the gate profile, optimization and control guidance of the process, and performing sensitivity analyzes of operating parameters during Al-CMP.…”

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confidence: 99%

An Aluminum Gate Chemical Mechanical Planarization Model for HKMG Process Incorporating Chemical and Mechanical Effects

Chen

2014

ECS J. Solid State Sci. Technol.

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In this work, a new aluminum gate chemical mechanical planarization (CMP) model is proposed in high-k metal gate (HKMG) process for controlling and simulating the metal gate height variation. It systematically captures the effects of mechanical abrasion and concentrations of different types of chemical reagents on material removal rate and surface height evolution. Based on the fundamentals of steady-state oxidation reaction and etched removal in addition to mechanical abrasion, the combinational synergistic interaction is described by separate kinetic parameters such as process parameters, pad properties and slurry chemistry. It can be seen that the removal rate and the coupled effects of the chemical additives are determined from a closed-form equation, making use of the concepts of chemical mechanical equilibrium, chemical kinetics and contact mechanics. The model prediction results show good agreement with the collected experimental data. The metal gate dishing post-Al-CMP is found to increase with increasing the pattern density when the line space is fixed. The dishing value increases with increasing the pattern density up to a certain maximum and then it decreases for a fixed pitch. The present model can be adopted to analyze the influence of the design pattern structures, slurry properties, pad characteristics and polishing conditions on removal rate and wafer surface evolution. The governing equation of aluminum removal and dishing effect reveal some insights into the polishing process and can be used for assisting in HKMG test pattern design and performing the sensitivity analyzes of operating parameters on surface topography during Al-CMP.With the steady shrinkage of the feature size and device geometry of modern integrated circuits (ICs), chemical mechanical planarization (CMP) has emerged as one of the most important solution for surface local and global planarization. Aluminum metal CMP (Al-CMP) process was once a key solution to form the Al damascene interconnects in back-end-of-line (BEOL) application. 1,2 However, due to the low resistivity and better reliability performance of copper, the Cu damascene approach has eventually taken up the mainstream in BEOL interconnect structures.In recent years, the introduction of high-k metal gate (HKMG) structure has enabled the resumption of Moore's Law at the 45/32 nm nodes, when conventional Poly/SiON gate stacks run out of steam. HKMG technology which adopts a replacement metal gate (RMG) approach promises to enable conventional scaling of the transistor as well as reduced stand-by power. Intel had the first 45 nm HKMG processor in volume production in 2007 and most of the foundries introduce HKMG to fabricate their 32/22 nm devices and products. 3 Correspondingly, poly opening polish (POP) processing before dummy poly removed and Al-CMP implementation after work function metal deposited, have been developed to fabricate the HKMG products. 4,5 During the Al metal gate CMP process, the combinational effect of the polishing pad, abrasive particles and chemi...

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confidence: 99%

An Aluminum Gate Chemical Mechanical Planarization Model for HKMG Process Incorporating Chemical and Mechanical Effects

Chen

2014

ECS J. Solid State Sci. Technol.

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“…Under acidic conditions, the main forms of aluminum are Al 3+ and Al 2 O 3 . 18 The oxidation state of aluminum is increased from 0 to +3, while the hydrogen ions in the acid are reduced to hydrogen gas. Notably, as the pH exceeded 5, the chemical reactions of aluminum shifted from the corrosion region to the passivation region, leading to reduced chemical reactivity and a reduced removal rate for aluminum.…”

Section: Resultsmentioning

confidence: 99%

The Role of Alanine in the Chemical Mechanical Polishing of Aluminum

Cao,

Wang,

Luo

et al. 2023

ECS J. Solid State Sci. Technol.

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With the evolution of integrated circuits, the transition from polycrystalline silicon to aluminum as the gate electrode has become prevalent due to its inherent advantages. This study considers the impacts of pH, H2O2 and alanine on the aluminum removal rate and surface roughness during chemical mechanical polishing (CMP) with abrasive colloidal silica. Alanine was incorporated as a complexing agent in the polishing slurry in an acidic environment. The mechanistic role of alanine in the aluminum CMP process was investigated with various techniques, including electrochemical tests, scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and UV–visible spectroscopy (UV–vis). Additionally, density functional theory (DFT) calculations were used to examine the quantum chemical parameters of alanine and elucidate the complexation mechanism. The experimental results indicated that at an alanine concentration of 1.5 wt%, the Al removal rate was 2124.07 Å min−1 with a surface roughness of 1.33 nm. The interactions between alanine and the aluminum ions (Al3+) yielded soluble Al-alanine complexes, which facilitated corrosion on the Al and enhanced the removal rate.

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“…In RMG-HKL, oxidation in O 3 is used for interface layer-SiO 2 (IL-SiO 2 ) formation prior to high-k dielectric deposition. Final H gate is set by the metal-CMP 18,21,23,24) following the EWF-+ fill-metal depositions. In this work, W vs Al are This work focus on RMG-HKL, but results are also valid for RMG-HKF.…”

Section: Device Fabricationmentioning

confidence: 99%

W versus Co–Al as Gate Fill-Metal for Aggressively Scaled Replacement High-k/Metal Gate Devices for (Sub-)22 nm Technology Nodes

Veloso

Chew

Schram

et al. 2013

Jpn. J. Appl. Phys.

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In this work we provide a comprehensive evaluation of a novel, low-resistance CoAl alloy vs. W to fill aggressively scaled gates with high aspect-ratios (H gate 50-60nm, L gate 20-25nm). We demonstrate that, with careful liner/barrier materials selection and tuning, well-behaved devices are obtained, showing: tight R gate distributions down to L gate 20nm, low-V T values, comparable DC and BTI behavior, and improved RF response. The impact of fillmetals intrinsic stress, including presence of occasional voids in narrow W-gates, on fabrication and performance is also explored.

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High K Metal Gate Aluminum CMP Challenges and Solutions

Cited by 11 publications

References 0 publications

An Aluminum Gate Chemical Mechanical Planarization Model for HKMG Process Incorporating Chemical and Mechanical Effects

An Aluminum Gate Chemical Mechanical Planarization Model for HKMG Process Incorporating Chemical and Mechanical Effects

The Role of Alanine in the Chemical Mechanical Polishing of Aluminum

W versus Co–Al as Gate Fill-Metal for Aggressively Scaled Replacement High-k/Metal Gate Devices for (Sub-)22 nm Technology Nodes

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