Ion energy control at substrates during plasma etching of patterned structures

Silapunt, Rardchawadee; Wendt, A.; Kirmse, K. H. R.

doi:10.1116/1.2803723

Cited by 11 publications

(9 citation statements)

References 20 publications

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“…External bias voltages are typically applied to the substrate to manipulate the ion energy distribution during processing [1]. It has been shown that adequate biasing of the substrate can significantly support the etch selectivity in semiconductor processing [2][3][4] or the synthesis of certain crystalline phases in the deposition of hard coatings [5,6].…”

Section: Introductionmentioning

confidence: 99%

Calibration of a miniaturized retarding field analyzer for low-temperature plasmas: geometrical transparency and collisional effects

Baloniak¹,

Reuter²,

Flötgen³

et al. 2010

J. Phys. D: Appl. Phys.

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Retarding field analyzers (RFAs) are important diagnostics to measure fluxes and energies of ions impinging onto the wall of a plasma reactor. Any quantitative use of the data requires a proper calibration, which is here performed for a miniaturized RFA. The calibration accounts for the transparencies of the RFA grids as well as for collisions inside the RFA. An analytical model is derived which covers both geometrical and collisional effects. The model is calibrated and experimentally verified using a Langmuir probe. We find that the transparency of an RFA is a random variable which depends on the individual alignment of the RFA grids. Collisions inside the RFA limit the ion current transfer through the RFA at higher pressures. A simple method is presented which allows one to remove these artefacts from the RFA data and to obtain quantitative ion velocity distributions.

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Section: Introductionmentioning

confidence: 99%

Calibration of a miniaturized retarding field analyzer for low-temperature plasmas: geometrical transparency and collisional effects

Baloniak¹,

Reuter²,

Flötgen³

et al. 2010

J. Phys. D: Appl. Phys.

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“…21 ͑The angle of the IEAD is respect to the normal to the wafer.͒ One method to control the ion energies incident on the wafer is using a nonsinusoidal bias waveform to narrow the spread in energy. [22][23][24][25] It has been demonstrated that selectivity can be significantly improved using a narrow ͑in energy͒ IEAD as afforded by nonsinusoidal waveforms where the average ion energy is tuned to a value between the threshold energies of the two materials. One strategy for PALE would be to employ nonsinusoidal biases to discriminate between the threshold energies during the passivation and etch steps, thereby possibly eliminating the need for different gas mixtures ͑and so eliminate the purge step͒.…”

Section: Introductionmentioning

confidence: 99%

Plasma atomic layer etching using conventional plasma equipment

Agarwal

Kushner

2008

Journal of Vacuum Science &Amp; Technology A: Vacuum, Surfaces, and Films

159

104

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The decrease in feature sizes in microelectronics fabrication will soon require plasma etching processes having atomic layer resolution. The basis of plasma atomic layer etching ͑PALE͒ is forming a layer of passivation that allows the underlying substrate material to be etched with lower activation energy than in the absence of the passivation. The subsequent removal of the passivation with carefully tailored activation energy then removes a single layer of the underlying material. If these goals are met, the process is self-limiting. A challenge of PALE is the high cost of specialized equipment and slow processing speed. In this work, results from a computational investigation of PALE will be discussed with the goal of demonstrating the potential of using conventional plasma etching equipment having acceptable processing speeds. Results will be discussed using inductively coupled and magnetically enhanced capacitively coupled plasmas in which nonsinusoidal waveforms are used to regulate ion energies to optimize the passivation and etch steps. This strategy may also enable the use of a single gas mixture, as opposed to changing gas mixtures between steps.

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“…Since a limitation of these approaches with respect to throughput is the existence of purge steps, Agarwal and Kushner 9 also examined the question if elimination of the purge steps is possible and self-limited etching can be achieved if the entire SiO 2 etching cycle is performed using a single gas mixture, and simply controlling ion bombardment energies during a cycle by changing RF bias. By utilizing a nonsinusoidal bias waveform, 96,97 they controlled ion energy distribution functions, and demonstrated self-limiting etching at 1 to several ML/cycle. This method is related to pulsed plasma approaches.…”

Section: Iii-v: Gaasmentioning

confidence: 99%

Atomic Layer Etching at the Tipping Point: An Overview

Oehrlein

Metzler

2015

ECS J. Solid State Sci. Technol.

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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Ion energy control at substrates during plasma etching of patterned structures

Cited by 11 publications

References 20 publications

Calibration of a miniaturized retarding field analyzer for low-temperature plasmas: geometrical transparency and collisional effects

Calibration of a miniaturized retarding field analyzer for low-temperature plasmas: geometrical transparency and collisional effects

Plasma atomic layer etching using conventional plasma equipment

Atomic Layer Etching at the Tipping Point: An Overview

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