A Study of Parameters Related to the Etch Rate for a Dry Etch Process Using NF₃/O₂and SF₆/O₂

Abstract

The characteristics of the dry etching of SiN :H thin films for display devices using SF 6 /O 2 and NF 3 /O 2 were investigated using a dual-frequency capacitively coupled plasma reactive ion etching (CCP-RIE) system. The investigation was carried out by varying the RF power ratio (13.56 MHz/2 MHz), pressure, and gas flow ratio. For the SiN :H film, the etch rates obtained using NF 3 /O 2 were higher than those obtained using SF 6 /O 2 under various process conditions. The relationships between the etch rates and the usual monitoring parameters-the optical emission spectroscopy (OES) intensity of atomic fluorine (685.1 nm and 702.89 nm) and the voltages and -were investigated. The OES intensity data indicated a correlation between the bulk plasma density and the atomic fluorine density. The etch rate was proportional to the product of the OES intensity of atomic fluorine ( (F)) and the square root of the voltages (√ ℎ + ) on the assumption that the velocity of the reactive fluorine was proportional to the square root of the voltages.

Charged particle dynamics and distribution functions in low pressure dual-frequency capacitively coupled plasmas operated at low frequencies and high voltages

“…This keeps the discharge stable and ensures collisionless sheaths as well as energetic vertical ion bombardment at the wafer. Similar discharge conditions are used for HAR dielectric plasma etching in CCPs [8][9][10][11][12][13][14][15]. The interest in this low-frequency and high voltage operation regime is the motivation of our studies.…”

Correlation of SiO2 etch rate in CF4 plasma with electrical circuit parameter obtained from VI probe in inductively coupled plasma etcher

“…They found that the RF bias impedance of a fundamental frequency was the most useful parameter for detecting the end point of oxide etching. Oh et al [6] studied the parameters related to the etch rates of nitride in SF 6 /O 2 and NF 3 /O 2 gas. Using VI probe and OES, they introduced the parameter proportional to both the flux of the atomic fluorine and the etch rate.…”

Control of electron velocity distributions at the wafer by tailored voltage waveforms in capacitively coupled plasmas to compensate surface charging in high-aspect ratio etch features

“…While positive ions are accelerated towards the wafer by the sheath electric field and hit it vertically and continuously with high energies, electrons reach the substrate during the local sheath collapse at low energies and with a wide angular distribution [8]. The etch process is driven by high energy ions and reactive radicals [9][10][11][12][13][14][15][16], but the fluxes of positive ions and electrons must balance at each surface element of a dielectric wafer locally on time average, including the bottom and the sidewalls of trenches [8,17,18]. In the presence of a wide angular distribution, electrons cannot penetrate deeply into HAR trenches.…”