Molecular layer etching of GaAs

128

106

Current trends in semiconductor device manufacturing impose extremely stringent requirements on nanoscale processing techniques, both in terms of accurately controlling material properties and in terms of precisely controlling nanometer dimensions. To take nanostructuring by dry etching to the next level, there is a fast growing interest in so-called atomic layer etching processes, which are considered the etching counterpart of atomic layer deposition processes. In this article, past research efforts are reviewed and the key defining characteristics of atomic layer etching are identified, such as cyclic step-wise processing, self-limiting surface chemistry, and repeated removal of atomic layers (not necessarily a full monolayer) of the material. Subsequently, further parallels are drawn with the more mature and mainstream technology of atomic layer deposition from which lessons and concepts are extracted that can be beneficial for advancing the field of atomic layer etching.

Section: The Early Days Of Atomic Layer Etchingmentioning

confidence: 99%

Atomic Layer Etching: What Can We Learn from Atomic Layer Deposition?

Faraz

Roozeboom

Knoops

et al. 2015

128

106

“…61,62 They published subsequently additional work using Ar ion bombardment, 63 or photon irradiation of a chlorine-coated GaAs surface. 44,64 Aoyagi et al 65 studied GaAs ALE using alternating Cl 2 exposure and synchronized low energy Ar + bombardment by applying a low bias voltage in an electron cyclotron resonance (ECR) plasma system. The ECR Ar discharge was continuously maintained, and Cl 2 was admitted for times up to 40 s to achieve adsorption of Cl atoms at the GaAs surface.…”

Section: Atomic Layer Etching Of Various Materials -A Brief Surveymentioning

confidence: 99%

Atomic Layer Etching at the Tipping Point: An Overview

Oehrlein

Metzler

2015

232

162

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...

“…Park et al 3 have reported a similar mechanism for atomic z E-mail: satyarth.suri@intel.com layer removal of Si using a combination of Cl 2 adsorption and Ne neutral beam. Such atomic layer etching processes have also been reported for GaAs 5 and Ge. 7 It is important to note here that exposure with energetic radicals or use of energetic ions may result in damage or modification of the next layer of atoms, thereby eliminating one of the potential benefits (damage-free processing) of ALEt.…”

Section: What Is Atomic Layer Etching?mentioning

confidence: 97%

“…The idealized sequence described in Figure 1a-1d enables formation of an anisotropic atomic layer removal of material. Several reports are present in the literature [2][3][4][5][6][7][8] where variations of the idealized flow have been successfully demonstrated. A requirement for this flow, and hence somewhat of a limitation, is that the modified surface layer released during the process in Figure 1c should be a stable volatile by-product so that it can be efficiently pumped out of the process chamber.…”

Section: What Is Atomic Layer Etching?mentioning

confidence: 99%

“…Etching of GaAs by Cl 2 adsorption followed by Ar + sputtering was among the first ALEt processes developed. 5,6 More recently, Jang, Yeom, and coworkers have demonstrated atomic layer control of III-V compounds using Cl adsorption and a Ne neutral beam to sputter, further minimizing damage relative to Ar plasma. They have demonstrated InP recess stopping on an InAlAs/InGaAs transistor channel.…”

Section: Potential Applications For Atomic Layer Etchingmentioning

confidence: 99%

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Atomic Layer Etching: An Industry Perspective

Carver

Plombon

Romero

et al. 2015

145

128

This paper provides an industry perspective on atomic layer etching (ALEt) process. Two process sequences representing two different methods of ALEt are described, followed by several examples where ALEt can be an enabling process technology in the semiconductor industry. The authors believe that there needs to be an increased understanding of surface functionalization, modification and chemistry-based material removal. We are confident that this review article will allow for increased scientific and technological solutions for enabling ALEt.