Negative charge injection to a positively charged SiO2 hole exposed to plasma etching in a pulsed two-frequency capacitively coupled plasma in CF4/Ar

Abstract

As microchips become smaller, the threat of damage to the device elements of Si semiconductors by charging during plasma etching will become significant. It will be of first importance to establish a plasma-etching technique that does not involve charging, i.e., “charging-free plasma processing.” Here, we utilize the effect of negative charge acceleration under a double layer in order to neutralize the charge inside a microstructure exposed to plasma etching. We have constructed a dual measurement system consisting of an emission in an interface and a contact hole charging on a SiO2 wafer during etching in two-frequency capacitively coupled plasma (2f-CCP) in CF4/Ar and pure Ar. A reduction in charging voltage is measured in the pulsed operation both of the plasma power source and of the wafer bias in the 2f-CCP in electronegative gases, CF4/Ar.

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

“…The upper electrode is used to generate high-density plasma and the lower electrode to obtain high-energy ion flux toward the substrate. We have confirmed the functional separation of the 2f-CCP by simulation and experiment [13], [14]. The high-frequency electrode is driven by 100 MHz with amplitude 300 V and the low-frequency electrode by 1 MHz with 700 V. The gas pressure is 100 mtorr with N (50%)-H (50%).…”

“…In this paper, we present the simulation results of a two-frequency capacitively coupled plasma (2f-CCP) [13], [14] based on relaxation continuum (RCT) model [15]- [17] with an N -H gas mixture. The plasma and neutrals are simulated self-consistently in the calculation by considering the reactions and transport of both.…”

Transport Coefficients For Electrons in Mixtures CF4/Ar/O2and CF, CF2or CF3Radicals

“…It is also of importance for understanding electronegative plasmas and for reducing charging damage by using double layers to accelerate negative ions into the charged high aspect ratio structures in dielectrics [23].…”

Plasma etching and feature evolution of organic low-k material by using VicAddress

“…These phenomena have been actually found in SiO 2 etching, and the wafer surface is changed from a pure SiO 2 to a interfacial CF-polymer layer with a lower mixing layer consisting of Si, O x , and F y [2]. In addition, the dielectric wafer is charged and the potential of the inside of the hole or trench will be locally distributed [3]. As a result, the surface process is a competition among charging, deposition, and etching, and the feature profile evolution is estimated under these competition by level-set method (see Fig.…”