Modeling of N<tex>$_2$</tex>–H<tex>$_2$</tex>Capacitively Coupled Plasma for Low-k Material Etching

Abstract

As the scale of semiconductors shrinks and the interconnect layer develops to tens level, the resistance-capacitance (RC) delay of signals through interconnection materials becomes a big obstacle for high-speed operation of integrated circuits. In order to reduce the RC delay, low-k materials will be used for intermetal dielectric (IMD) materials. As a result, new etching conditions must be developed to match the material properties. We present the modeling results of a two-frequency capacitively coupled plasma (2f-CCP) with N 2 -H 2 gas mixture, which is known as a promising one for organic low-k materials etching. We have developed a self-consistent simulation tool which includes neutralspecies transport model, based on the relaxation continuum (RCT) model. Not only the plasma transport and spatial distribution, but also those of neutrals are important issues for the etching process. For the etching of low-k materials by N 2 -H 2 plasma, N and H atoms have a big influence on the materials. Moreover, the distributions of excited neutral species influence the plasma density and profile. Therefore, we include the neutral transport model as well as plasma one in the calculation. The plasma and neutrals are calculated self-consistently by iterating the simulation of both species until a spatiotemporal steady-state profile could be obtained. In the simulation of neutral species, the interactions of excited states and vibrational levels of both N 2 and H 2 molecules are considered too. The profiles of periodic steady-state plasma and neutrals species in the 2f-CCP system is discussed.Index Terms-H 2 -N 2 plasma, low-material etching, plasma etching, relaxation continuum (RCT) modeling, two-frequency capacitively coupled plasma (2 -CCP).

Non-Neutral/Quasi-Neutral Plasma Edge Definition for Discharge Models: A Numerical Example for Dual Frequency Hydrogen Capacitively Coupled Plasmas

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Energy analysis of hyperthermal hydrogen atoms generated through surface neutralisation of ions

“…semiconductor processing. Surface treatment by neutrals avoids problems with surface charging effects, frequently encountered when using common ion treatment, especially for low-k materials [1][2][3][4]. Furthermore, hyperthermal atoms can also play a vital role in the resulting morphology of thin films in plasma-enchanced chemical vapour deposition (PECVD) [5,6].…”

Study of Low Pressure Inductively Coupled Plasmas: Effects of the DC Bias and Gas Flow Rate

“…21) The electron impact cross-section data and chemical reaction rates for the above-described species are taken from the published literature and opened database. [21][22][23][24][25][26][27][28] The basic equations for the plasma simulation used in this research include a pair of drift diffusion equations for the electrons, a modified Maxwell-Stefan equation for the ion and neutral species, a Possion's equation for the space charge electric field, and an electromagnetic field equation for the induced electric field. In this work, the plasma simulations are coupled with the fluid equations, which are combined by the continuity equation and momentum equation.…”