Observation of inverse reactive ion etching lag for silicon dioxide etching in inductively coupled plasmas

Doemling, M. F.; Rueger, N. R.; Oehrlein, G. S.

doi:10.1063/1.116772

Cited by 54 publications

(41 citation statements)

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“…Radicals may have to undergo several surface collisions in order to reach the bottom of contact holes or trenches. The reduction in radical flux to surface elements at the bottom of features by surface recombination has been discussed extensively, 36,39,107,143 and depends strongly on the value of the recombination coefficient r. This potentially could lead to situations where one location and material may exhibit self-limited adsorption at a monolayer, whereas another material may show multi-layer adsorption. Additionally, the redeposition of etch product on the feature sidewalls has to be considered.…”

Section: Issues and Needsmentioning

confidence: 99%

Atomic Layer Etching at the Tipping Point: An Overview

Oehrlein

Metzler

2015

ECS J. Solid State Sci. Technol.

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232

162

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The ability to achieve near-atomic precision in etching different materials when transferring lithographically defined templates is a requirement of increasing importance for nanoscale structure fabrication in the semiconductor and related industries. The use of ultra-thin gate dielectrics, ultra thin channels, and sub-20 nm film thicknesses in field effect transistors and other devices requires near-atomic scale etching control and selectivity. There is an emerging consensus that as critical dimensions approach the sub-10 nm scale, the need for an etching method corresponding to Atomic Layer Deposition (ALD), i.e. Atomic Layer Etching (ALE), has become essential, and that the more than 30-year quest to complement/replace continuous directional plasma etching (PE) methods for critical applications by a sequence of individual, self-limited surface reaction steps has reached a crucial stage. A key advantage of this approach relative to continuous PE is that it enables optimization of the individual steps with regard to reactant adsorption, self-limited etching, selectivity relative to other materials, and damage of critical surface layers. In this overview we present basic approaches to ALE of materials, discuss similarities/crucial differences relative to thermal and plasma-enhanced ALD, and then review selected results on ALE of materials aimed at pattern transfer. The overview concludes with a discussion of opportunities and challenges ahead. A requirement of increasing importance for nanoscale device fabrication is the ability to achieve atomic scale etching control and materials selectivity during pattern transfer.1-8 An etching method corresponding to Atomic Layer Deposition (ALD), i.e. Atomic Layer Etching (ALE), is expected to satisfy these needs as critical dimensions continue to shrink below the 10 nm scale.Demonstrations of self-limited dry etching methods capable of near-atomic resolution have a long history in the dry etching community and a brief review will be presented below. Key challenges for these approaches have been specialized equipment, long process times and low throughput.9,10 However, a recent demonstration using a commercial plasma etch tool 10 and activities within the dry etching community 11 provide indications that the situation has changed, and that we may have reached for ALE the Tipping Point which Gladwell defined as the "the moment of critical mass, the threshold, the boiling point" when "ideas and products and messages and behaviors spread like viruses do".12 This is due to several factors, including unprecedented demands on dry etching technology introduced by the semiconductor device evolution according to Moore's law that can be satisfied by atomic layer etching, advanced capabilities in plasma etch, and the existence of a critical level of information on plasma etch and ALD methods as applied in the semiconductor fabrication space.In this article we will provide a review of background of these approaches, and focus on issues that have to be overcome for widespread implement...

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Section: Issues and Needsmentioning

confidence: 99%

Atomic Layer Etching at the Tipping Point: An Overview

Oehrlein

Metzler

2015

ECS J. Solid State Sci. Technol.

Self Cite

232

162

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“…1,2 For example, while an ion-neutral synergy model with pure neutral flux shadowing appears to be consistent with a wealth of ARDE measurements in semiconductors, 2 it does not hold for the etching of insulators. Indeed, Doemling et al 3 have reported inverse ARDE of trenches and holes in SiO 2 in a high-density CHF 3 plasma at 20 mTorr. Remarkably, they also reported aspect ratio independent etching ͑ARIE͒ when the pressure was lowered to 6.7 mTorr; for fixed etching time, the etch depth was the same for a variety of trench widths and hole diameters ͑as low as 0.25 m, corresponding to an aspect ratio of 8.5:1͒.…”

Section: ͓S0003-6951͑97͒03930-2͔mentioning

confidence: 99%

“…Even in the best of cases, with an ad hoc exponential dependence of inhibitor flux, they calculated that ARIE should break down at an aspect ratio of Ϸ5:1. Even if the ''magic'' value of the required inhibitor flux was accidentally chosen by Doemling et al, 3 their smallest trench ͑0. 25 m͒ should have been etched less deep than the larger trenches.…”

Section: ͓S0003-6951͑97͒03930-2͔mentioning

confidence: 99%

Aspect ratio independent etching of dielectrics

Hwang

Giapis

1997

Applied Physics Letters

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Monte Carlo simulations of pattern-dependent charging during oxide etching predict that the etch rate scaling with aspect ratio breaks down when surface discharge currents are significant. Under conditions of ion-limited etching and no inhibitor deposition, the etch depth depends on the maximum incident ion energy, reaction threshold, and surface discharge threshold, and is the same irrespective of the trench width ͑р0.5 m͒.

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“…[15,16] This effect, known as RIE lag, ratio features. [17,18] This work investigates the problem of shrinking asymmetric holes uniformly, the physical limitations of depositing in shadowed features, and which plasma parameters can give the best results. There is difficulty in equally shrinking features with very short, confined dimensions with longer dimensions.…”

Section: Introductionmentioning

confidence: 99%

Controlling Asymmetric Photoresist Feature Dimensions during Plasma-Assisted Shrink

Fox-Lyon

Metzler

Oehrlein

et al. 2014

Plasma Process. Polym.

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Plasma-assisted shrink (PAS) of features, involving plasma deposition onto sidewalls to shrink features has been described in the past for symmetric features. In this work we explore shrinkage of asymmetric features using fluorocarbon-based plasma deposition. Using top-down and cross-section scanning electron microscopy, we find the dependencies of this shrink process on top-down blanket deposition thickness, pressure, source power, and deposition plasma chemistry with the aim of achieving the best 1:1 length to width shrink (DL:DW) of asymmetric features.

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Observation of inverse reactive ion etching lag for silicon dioxide etching in inductively coupled plasmas

Cited by 54 publications

References 0 publications

Atomic Layer Etching at the Tipping Point: An Overview

Atomic Layer Etching at the Tipping Point: An Overview

Aspect ratio independent etching of dielectrics

Controlling Asymmetric Photoresist Feature Dimensions during Plasma-Assisted Shrink

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