An Oxide Chemical Mechanical Planarization Model for HKMG Structures

As the characteristic size of integrated circuits has continued to shrink, there has been increasing interest in using aluminum (Al) as the gate material. Here, we have looked at the role ethylenediamine tetraacetic acid dipotassium (EDTA-2K) plays in the chemical mechanical polishing (CMP) of Al for use as a gate material. Currently, the preferred approach to CMP is to use colloidal silica as an abrasive, EDTA-2K as the complexing agent, and H2O2 as the oxidant. We have explored the influence of EDTA-2K and H2O2 on the Al removal rate (RR) during CMP. The results show that when the concentration of EDTA-2K is 1 wt%, the removal rate reaches 3450 Å/min, and the surface roughness is 0.425 nm. The mechanism of the action of EDTA-2K during CMP was studied through particle size distribution analysis, X-ray photoelectron spectroscopy, electrochemical tests, and UV-visible spectroscopy. The results show that EDTA-2K reacts with aluminum ions (Al3+) to form a soluble Al-EDTA complex, which promotes the corrosion rate on the Al surface and thus increases the removal rate of Al.

mentioning

confidence: 99%

The Role of EDTA-2K in the Chemical Mechanical Polishing of Aluminum

Yang

Mei

Xie

et al. 2023

“…1, the adoption of an aluminum metal gate reduces the channel carrier mobility and mitigates the impact of remote coulomb scattering on the high-k gate dielectric layer. 3,4 However, the 45 nm IC process requires planarization and removal of unwanted films at the nanoscale because of the depth-of-focus limitations of shortwavelength (193/245 nm) optical lithography, and the uniformity of the planarization process must be maintained over a length scale of approximately eight orders of magnitude in 300 mm diameter wafers. These planarization and roughness requirements constitute significant challenges for all IC manufacturers.…”

mentioning

confidence: 99%

The Role of Alanine in the Chemical Mechanical Polishing of Aluminum

Cao,

Wang,

Luo

et al. 2023

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.

“…In chip-scale CMP modeling, the contact pressure distributed on the design patterns is a key parameter in DFM-driven CMP simulation and has a large effect on the MRR and surface topography. 42 As for the above mentioned chip-scale CMP models, there still exist some aspects needed to be pointed out as a basis to explore better solution for CMP simulation. Up to now, chip-scale CMP models only consider one or two aspects of the mechanical abrasion factor and design pattern effect in constructing the removal rate equation and ignoring the influence of the chemical reaction and slurry transport effect, which cannot give a fundamental insight into the polishing mechanism in the CMP process.…”

mentioning

confidence: 99%

A Physics-Based Chip-Scale Surface Profile Model for Tungsten Chemical Mechanical Planarization

Cao

Liu

2023

Self Cite

A novel physics-based chip-scale surface profile model is proposed to focus on investigating the influence of the design pattern effects on the tungsten surface topography in the chemical mechanical planarization (CMP) process. The two-scale contact pressure computation method is constructed to obtain an accurate pressure distribution between the wafer surface and the polishing pad. The chip-scale contact mechanics-based global pressure has been first introduced to capture the long range height variation of W CMP caused by deposition and polishing processes. Then, the feature-scale pattern dependent effect is considered to accurately calculate the local contact pressure which is further integrated with the fundamental of steady-state oxidation reaction to construct a new material removal rate model used for simulation of surface height evolution. The model prediction results are consistent with the collected experimental data in predicting the dishing effect at different slurry conditions. The present CMP model can be utilized to assist in analyzing the influence of the design pattern effects on the wafer surface topography and be readily incorporated into a design for manufacturability flow to form a chip-scale planarity simulator to detect the hotspots of the entire design layout.