Selectivity (oxide/nitride polish rate) is a critical factor during chemical mechanical polishing (CMP) of shallow trench isolation (STI) structure, and it can be modified by adding amino acids to the slurry. The role of adsorption of the amino acids L-proline and L-arginine, on silicon dioxide and silicon nitride surfaces was characterized as a function of pH and concentration using thermogravimetric analysis. The results suggest that the adsorption behavior does not correlate with the polishing behavior of STI CMP and hence it may not play a key role in changing the selectivity. © 2006 The Electrochemical Society.

Srinivasan Ramanathan

Department Of Chemical Engineering

Adsorption

Amino acids

CHEMICAL MECHANICAL POLISHING

silica

Thermogravimetric analysis

Adsorption behavior

POLISHING BEHAVIOR

Shallow trench isolation (STI)

Silicon nitride

Fulltext

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IIT Madras

Role of Amino-Acid Adsorption on Silica and Silicon Nitride Surfaces during STI CMP

Electrochemical and Solid-State Letters

Amino acids, when used with ceria based slurries, yield high selectivity in shallow trench isolation chemical mechanical polishing (CMP). However, the presence of impurities in the abrasives also plays a role in determining the selectivity. Experiments were performed with two different ceria abrasives, one with high purity and the other with controlled lanthanum doping. Various amino acids were evaluated in order to identify the nature of interaction between the additives and the abrasives. The abrasives were further characterized using transmission electron microscopy, X-ray diffraction and X-ray photo-electron spectroscopy. The removal rate results show that glycine and proline are sensitive to the La doping in the ceria abrasive whereas the other amino acids studied suppress the nitride removal irrespective of the purity of the abrasives. Thermo-gravimetric analysis shows that the extent of adsorption of glycine or proline on ceria depends on the presence of La doping, whereas the other amino acids adsorb equally well on ceria abrasives with or without La doping. © 2015 Elsevier Ltd. All rights reserved.

Materials Science in Semiconductor Processing

Effect of lanthanum doping in ceria abrasives on chemical mechanical polishing selectivity for shallow trench isolation

Electrical isolation of the billion or so active components in each integrated device is achieved using shallow trench isolation (STI) which requires chemical mechanical planarization (CMP) involving silicon dioxide removal at a high rate and stopping on an underlying silicon nitride film. Several colloidal slurries with various additives can yield the desired high rate selectivity between the oxide and nitride films during CMP while maintaining an acceptably low nitride rate. Here, many of such high selectivity STI CMP slurries described in the literature are reviewed along with the characteristics of the colloidal dispersions like the abrasives, additives, the interactions between them and with the films being planarized and the associated pH range in which the high selectivity is observed. The mechanisms proposed to explain the high reactivity of ceria with oxide, the role of additives in suppressing the nitride removal rate and resulting high selectivity are discussed. Reduction of a multitude of defects in post-CMP processed STI structures still remains an important challenge, especially as the feature sizes continue to shrink. © The Author(s) 2015. Published by ECS.

ECS Journal of Solid State Science and Technology

Shallow trench isolation chemical mechanical planarization: A review

Ceria based slurries with additives are widely used in shallow trench isolation (STI) chemical mechanical planarization (CMP) process to obtain high selective removal of silicon dioxide over silicon nitride. In this study ceria from different sources were used as abrasives and l-proline and l-glutamic acid were used as additives, with a focus on identifying the interactions between abrasives and additives and their effect of selectivity. Ceria particles were characterized using X-ray diffraction (XRD), energy dispersive X-ray (EDX) spectroscopy, transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS) while the additive abrasive interactions were evaluated by UV-Visible spectroscopy and inductively coupled plasma optical emission spectroscopy (ICP-OES) analysis. While slurries with l-proline yielded high selectivity only with certain type of ceria, slurries with l-glutamic acid were found to be less sensitive to the ceria source than those with l-proline, and yielded high selectivity regardless of the source of ceria used. The purity of the abrasive and its crystal structure appear to play a significant role in determining the selectivity. © 2013 Elsevier B.V. All rights reserved.

Microelectronic Engineering

Abrasive and additive interactions in high selectivity STI CMP slurries

The effect of hydrogen peroxide in chemical mechanical planarization slurries for shallow trench isolation was investigated. The various abrasives used in this study were ceria, silica, alumina, zirconia, titania, silicon carbide, and silicon nitride. Hydrogen peroxide suppresses the polishing of silicon dioxide and silicon nitride surfaces by ceria abrasives. The polishing performances of other abrasives were either unaffected or enhanced slightly with the addition of hydrogen peroxide. The ceria abrasives were treated with hydrogen peroxide, and the polishing of the work surfaces with the treated abrasive shows that the inhibiting action of hydrogen peroxide is reversible. It was found that the effect of hydrogen peroxide as an additive is a strong function of the nature of the abrasive particle. © 2008 Elsevier B.V. All rights reserved.

Applied Surface Science

The effect of hydrogen peroxide on polishing removal rate in CMP with various abrasives

In this study chemical mechanical planarization slurries for shallow trench isolation exhibiting high oxide to nitride polish rate selectivity were investigated and it was found that the abrasives play a major role in suppressing the nitride polish rate and enhancing selectivity. When glutamic acid is used as a selectivity enhancing additive, only ceria based slurries exhibit high selectivity while silica based slurries show low selectivity under identical conditions. A mechanism involving active sites on the ceria abrasive and interaction of glutamic acid with the active sites is proposed to explain the role of abrasive in enhancing selectivity. © 2008 Elsevier B.V. All rights reserved.

Role of abrasives in high selectivity STI CMP slurries

International Journal of Current Microbiology and Applied Sciences

Effect of Biochar, Mulch and Ppfm Spray on Leaf Relative Water Content, Leaf Proline, Chlorophyll Stability Index and Yield of Cotton under Moisture Stress Condition

Interfacial Reactivity Between Ceria and Silicon Dioxide and Silicon Nitride Surfaces

Materials Science and Engineering: R: Reports

Chemical mechanical planarization for microelectronics applications

Langmuir

Adsorption and Thermal Condensation Mechanisms of Amino Acids on Oxide Supports. 1. Glycine on Silica

Chemical-Mechanical Planarization of Semiconductor Materials Springer Series in Materials Science

Introduction

Role of amino-acid adsorption on silica and silicon nitride surfaces during STI CMP

Journal	Electrochemical and Solid-State Letters
ISSN	10990062
Open Access	Yes