Transients using low-high pulsed power in inductively coupled plasmas

Abstract

Pulsed inductively coupled plasmas (ICPs) are widely deployed in the fabrication of semiconductor devices. Pulse repetition frequencies of up to tens of kHz are commonly used during plasma etching for the high power densities they generate during the pulse-on period, and for their unique chemistries during the pulse-off period. The use of highly attaching halogen gases produces low electron densities during the pulse-off period, and these low densities can result in instabilities, E-H transitions and ignition delays when applying power on the next pulse. To mitigate these possibilities, a low-level power environment could be maintained during 'pulse-off' to moderate the minimum plasma density, therefore reducing ignition delays and enhancing plasma stability. In this work, ICPs sustained by 5 kHz pulsed power using Ar/Cl 2 mixtures at 20 mTorr were computationally investigated using a high-power, low-power format. For these conditions, the computed electron temperature (T e ) reaches a quasi-steady state during both the high-and low-power excitation. The model predicts that within the electromagnetic skin-depth, T e spikes to a high value during a low-to-high power transition, and to a low value during a high-to-low power transition. At the same time, a few cm above the substrate, there is little modulation in T e , as electron power convected from the skin depth disperses in traversing the reactor. The positive and negative spikes, and convection of transients across the reactors, are functions of power ramping time and gas mixtures.

Modeling of plasma processing reactors: review and perspective

“…Maximum value, range of values plotted, and units for contour labels are indicated in each image. These results are from Qu et al 65 …”

“…These results are from Krüger et al 64 Plasma properties from a hybrid model of ICP are shown in Fig. 16 from a paper by Qu et al 65 Instead of the Monte Carlo module, Kolobov and Arslanbekov 66 coupled the spatially dependent Boltzmann equation solver to a fluid plasma model. Two-term approximation was used to reduce the number of dimensions.…”

“…The models can, therefore, provide concrete guidance for LTP system design in addition to physics understanding. In this section, we provide our 65 perspective on deficiencies in the current plasma models and areas for which R&D effort would enhance the utility of plasma models.…”

Science-based, data-driven developments in plasma processing for material synthesis and device-integration technologies

“…This is determined by the electromagnetic skin depth. 64) The dynamics of power matching to pulsed ICPs of Ar/Cl 2 mixtures of tens of mTorr pressure using fixed-component impedance matching networks were investigated. 65) This early power coupling enables a more rapid ramp-up in the plasma density while being mismatched during the inductively coupled (H)-mode later in the pulse.…”

Spatio-temporal measurements of overshoot phenomenon in pulsed inductively coupled discharge*

“…Then they used high-low pulsed power to adjust the minimum plasma density, which reduces ignition delay and enhances plasma stability. [9] Han et al [10] measured the time-resolved magnetic field, electron density, and electron temperature for pulsed argon plasma. They found that a "ring" shape density profile appears at the initial stage of discharge, which then evolves to a peak in the middle of the chamber.…”