Characterization of SiO₂ Over Poly-Si Mask Etching in Ar/C₄F₈ Capacitively Coupled Plasma

Abstract

This research involved an experimental investigation of the relationship between the plasma parameters and etching properties of SiO 2 over poly-Si mask in Ar/C 4 F 8 capacitively coupled plasma (CCP). In these experiments, the etching process was conducted in CCP and the external conditions such as the applied power, pressure, and gas ratio were varied. In addition, the density of radicals, which dominantly participate in surface reactions, the electron density, and the self-bias voltage were measured. As a result, deposition of the CF x polymer film on the poly-Si mask lowered the electron density and self-bias voltage and the etch rate of the target and the mask increased as the internal parameters of the plasma increased. This result indicated that the electron density and the self-bias voltage, which represent the physical etch elements of ion flux and energy, respectively, have a marked influence on the etching process. Consequently, our work led us to propose a critical value, which is the product of the electron density and self-bias voltage, n e V bias , to analyze the etching mechanism. Our results are also expected to serve as a basic processing database that enables an in-depth understanding of etching.

Contribution of Ion Energy and Flux on High-Aspect Ratio SiO2 Etching Characteristics in a Dual-Frequency Capacitively Coupled Ar/C4F8 Plasma: Individual Ion Energy and Flux Controlled

“…Plasma, which is composed of charged and neutral particles, has been widely used in material processing due to its chemically reactive species and energetic ions, which can activate and modify the surface of materials [ 1 ]. These characteristics have made plasma processing a significant tool in semiconductor fabrication, particularly in high-aspect ratio (HAR) etching for creating three-dimensional transistor structures and improving transistor stacking [ 2 , 3 , 4 ].…”

“…Due to its complexity, the exact etching mechanism has yet to be clearly understood; etching depends on various internal parameters of plasma and chemical species, which are difficult to measure and control due to the complex nature of plasma. As a result, most experimental studies have analyzed the effects of external parameters such as gas composition, bias voltage, and power on HAR etching characteristics [ 2 , 3 , 10 , 11 , 12 ].…”

Determination of Plasma Potential Using an Emissive Probe with Floating Potential Method

“…Plasma, composed of charged and neutral particles, has been widely used in material processing, since it provides physically energetic ion bombardment and chemically reactive species on the material surface. In particular, plasma has played a significant role in plasma processes such as plasma etching [ 1 , 2 , 3 ], ashing [ 4 ], deposition [ 5 ], and plasma decomposition [ 6 , 7 ]. To analyze the process chemistry and mechanism, several instruments have been developed and utilized, such as voltage–current probes [ 8 , 9 ], optical emission spectroscopy [ 10 , 11 ], and quadrupole mass spectrometers [ 12 , 13 ].…”

Crossing Frequency Method Applicable to Intermediate Pressure Plasma Diagnostics Using the Cutoff Probe

“…Composed of physically energetic charged particles and chemically reactive neutral particles, plasma has been widely used in various fields including material fabrication and nuclear fusion as well as medical, environmental, and aerospace industries [ 1 , 2 ]. Plasma processing techniques such as plasma etching [ 3 , 4 , 5 , 6 , 7 ], ashing [ 8 , 9 , 10 , 11 ], and deposition [ 12 , 13 , 14 , 15 , 16 ] are the most important steps to fabricate the high-end memory and system semiconductors used in internet of things and artificial intelligence technologies. For plasma deposition in particular, plasma sputtering, plasma-enhanced chemical vapor deposition (PECVD), and plasma-enhanced atomic layer deposition (PEALD) approaches have been widely used for their high deposition rates, low-temperature processing, good film conformality, and high film uniformity [ 12 , 13 , 17 , 18 ].…”