Friday, July 3, 2020

ALD Hafnium oxide as an enabler for competitive ferroelectric devices

Here is a new paper from NaMLab on ferroelectric hafnium oxide applications entitled "Hafnium oxide as an enabler for competitive ferroelectric devices"

Ferroelectric materials offer the promise to realize low power memory devices and show negative capacitance operation that could lead to novel electronic devices. Although intense research on realizing different memory device concepts based on three different readout schemes have been subject to intense research, the commercial success is limited to low density ferroelectric random access memories based on a direct capacitor readout. The complexity of integrating ferroelectric materials into CMOS processes has limited successful implementations. Ferroelectricity in hafnium oxide related material systems could overcome this limitations for memories and at the same time enable new devices based on negative capacitance.

New ALD chemistry for ultra-thin gas sensors

[ LINK] The application of zinc oxide layers in industry is manifold and ranges from the protection of degradable goods to the detection of toxic nitrogen oxide gas. Such layers can be deposited by atomic layer deposition (ALD) which employs typically chemical compounds, or simply precursors, which ignite immediately upon contact with air, i.e. are highly pyrophoric. An interdisciplinary research team at Ruhr-Universität Bochum (RUB) has now established a new fabrication process based on a non-pyrophoric zinc precursor that can be processed at temperatures low enough to allow plastics to be coated. The team published their report in the journal Small.

Lukas Mai – he is reflected in a thin film – and Anjana Devi. Credit: RUB, Marquard

More information: Lukas Mai et al. Zinc Oxide: From Precursor Chemistry to Gas Sensors: Plasma‐Enhanced Atomic Layer Deposition Process Engineering for Zinc Oxide Layers from a Nonpyrophoric Zinc Precursor for Gas Barrier and Sensor Applications (Small 22/2020), Small (2020). DOI: 10.1002/smll.202070122

Thursday, July 2, 2020

Save the date - AVS ALD & ALE 2021 June 27-30, 2021, Tampa, Florida

Save the Date
June 27-30, 2021, Tampa, Florida
The AVS 21st International Conference on Atomic Layer Deposition (ALD 2021) featuring the 8th International Atomic Layer Etching Workshop (ALE 2021) will be a three-day meeting dedicated to the science and technology of atomic layer controlled deposition of thin films and now topics related to atomic layer etching. Since 2001, the ALD conference has been held alternately in the United States, Europe and Asia, allowing fruitful exchange of ideas, know-how and practices between scientists. This year, the ALD conference will again incorporate the Atomic Layer Etching 2021 Workshop (ALE 2021), so that attendees can interact freely. The conference will take place Sunday, June 27-Wednesday, June 30, 2021, at the JW Marriott Tampa Water Street in Tampa, Florida.

As in past conferences, the meeting will be preceded (Sunday, June 27) by one day of tutorials and a welcome reception. Sessions will take place (Monday-Wednesday, June 28-30) along with an industry tradeshow. All presentations will be audio-recorded and provided to attendees following the conference (posters will be included as PDFs). Anticipated attendance is 800+.
Key Deadlines:
Abstract Submission Deadline: February 3, 2021
Author Acceptance Notifications: March 16, 2021
Early Registration Deadline: May 14, 2021
Hotel Reservation Deadline: June 4, 2021
Manuscript Deadline: November 1, 2021
ALD Program Chairs
Program Chair:
Sean Barry (Carlton University, Canada)
Program Co-Chair:
Scott Clendenning (Intel, USA)
ALE Program Chairs

Program Chair:
Jane Chang (University of California, Los Angeles, USA)

Program Co-Chair:
Thorsten Lill (Lam Research, USA)

Wednesday, July 1, 2020

AVS 2020 International Twitter Poster Competition

The American Vacuum Society (AVS) is excited to announce the AVS 2020 International Twitter Poster Competition, a new online venue to share your research with a global audience. We hope you will join us to disseminate your latest findings, connect with your research community, and meet new colleagues.

Registration deadline has been extended to July 6, 2020. And by popular demand, there are two new technical categories: Quantum Science (#AVS_Quantum) and Astrochemistry and Space Science (#AVS_Astrochem).

Monday, June 29, 2020

JVSTA 2019 Best ALD Paper Award Winner

As announced today at the Virtual AVS ALD Conference by Prof. Kessels - Congratulations to the winner of the 2019 Best ALD Paper Award, selected from papers presented at the 19th International Conference on Atomic Layer Deposition (ALD 2019) and published in JVST A.

Correlation between SiO2 growth rate and difference in electronegativity of metal–oxide underlayers for plasma enhanced atomic layer deposition using tris(dimethylamino)silane precursor

Erika Maeda, Toshihide Nabatame, Masafumi Hirose, Mari Inoue, Akihiko Ohi, Naoki Ikeda, and Hajime Kiyono JVST A 38, 032409 (2020) Read More

AVS ALD 2020 starts today and RASIRC is presenting and contributing with the latest results using´peroxide and hydrazine in Atomic Layer Porcessing

RASIRC is contributing to two oral and two poster presentations at the AVS ALD2020 Virtual conference starting today. The results summarize the latest development using either peroxide (H2O2) or hydrazine (N2H4) as powerful co-reactants in atomic layer processing of high-quality films with higher overall performance beyond that of classical thermal or plasma ALD processes.

Atomic Layer Annealing of AlN to Template The Growth of High Thermal Conductivity Heat Spreader Films (LINK)

Scott Ueda‚ Aaron McLeod (University of California‚ San Diego); Michelle Chen‚ Chris Perez‚ Eric Pop (Stanford University); Dan Alvarez (RASIRC); Andrew Kummel (University of California‚ San Diego)

In this study of AlN Atomic Layer Annealing (ALA)‚ two metal precursors (TMA and TDMAA) were compared using anhydrous N2H4 as a co-reactant and argon ions with tuned energy for the third pulse. High-quality AlN films are deposited with large grain size and low C/O contamination which can then be used as a templating layer for further high-speed AlN film growth.

Effect of Copper Surface Condition on Passivation Characteristics for Applications to Area Selective Atomic Layer Deposition (LINK)

Su Min Hwang (University of Texas at Dallas); Harrison Kim‚ Jin-Hyun Kim (The University of Texas at Dallas); Yong Chan Jung (University of Texas at Dallas); Luis Fabian Pena‚ Kui Tan‚ Jean-Francois Veyan (The University of Texas at Dallas); Dan Alvarez‚ Jeffrey Spiegelman (RASIRC); Kashish Sharma‚ Paul Lemaire‚ Dennis Hausmann (Lam Research Corp.); Jiyoung Kim (University of Texas at Dallas)

Herein‚ electroplated Cu films were treated using glacial acetic acid (CH3COOH) and anhydrous N2H4‚ respectively.4 After cleaning‚ the Cu samples were immersed in a 1 mM solution of octadecanethiols (ODTs) in ethanol for 20 h. To elucidate the surface chemistry and stability of ODTs‚ the passivated Cu samples were loaded into an in-situ reflectance absorption infrared spectroscopy (RAIRS) system equipped with an ALD chamber‚ then ALD of AlOx process was performed using TMA and H2O at 120 oC. During surface cleaning‚ CH3COOH removes surface adventitious contaminants (e.g.‚ –CHx‚ –CO3‚ and –OH)‚ and most importantly‚ reduces the surface oxide (Cu2O) to metallic copper by forming copper acetate as an intermediate material. In the ex-situ XPS and RAIRS‚ the SAMs on the CH3COOH-treated Cu sample gives poor selectivity of ALD-AlOx compared to the SAMs on the as-is Cu and N2H4-treated Cu‚ respectively. It implies that the residual copper acetate on the surface can affect the chemisorption of ODTs during passivation‚ eventually attributing a relatively lower surface coverage‚ poor thermal stability of ODTs‚ and poor selectivity during ALD process. To circumvent the issue‚ the effect of post-treatment after surface cleaning with CH3COOH was investigated. Vacuum treatment of the sample under the UHV condition (~10-8 Torr) can partially reduce the copper acetate by forming -CHx and -OH species. However‚ a post-annealing at 75 oC effectively removes the copper acetate and residual contaminants on the surface‚ which can improve not only ODTs quality in the passivation process but also the increase of nucleation delay during the consecutive ALD process. The detailed experimental results will be presented.

Thermal SiNx Using NH3 and Anhydrous Hydrazine as Nitriding Agents (LINK)

Su Min Hwang‚ Dan Le‚ Arul Ravichandran‚ Aswin Kondusamy (University of Texas at Dallas); Dan Alvarez‚ Jeffrey Spiegelman (RASIRC); Jiyoung Kim (University of Texas at Dallas)
Deposition of ultrathin and uniform SiNx films with high conformality is required for ULSI due to application restrictions‚ such as thickness and complicated surface areas. In general‚ the plasma-enhanced ALD (PEALD) process allows a low temperature process for such film deposition‚ but potentially results in poor conformality‚ creates surface damage‚ and is not applicable on sensitive substrates. The thermal ALD (tALD) process can overcome these issues; however‚ it requires a higher deposition temperature range for SiNx films. In this study‚ we focus on establishing a high quality SiNx tALD deposition process at relatively low temperatures (350 °C – 650 °C) for ammonia (NH3) and evaluate the properties of films deposited using hydrazine.
In this experiment‚ hexachlorodisilane (HCDS) is used as the source of silicon‚ along with BRUTE hydrazine and ammonia as the precursors for nitrogen. A PEALD/ tALD chamber (Rocky Mountain Vacuum Tech Inc.) is employed to deposit SiNx films with a working pressure between 150 – 160 mTorr. Furthermore‚ to eliminate the possibility of condensation of precursor or residual products‚ the chamber walls and precursor delivery lines are heated to 120 °C and 100 °C‚ respectively. The experimental temperature range is established from 350 °C to 650 °C. At the temperature range of 450 °C – 550 °C‚ the index of refraction (R.I.) of SiNx films deposited using hydrazine is up to 2.0‚ which further coincides with the earlier reported result‚ with a R.I. as high as 2.1.
Good growth rate, high etch resistance, and high uniformity SiNx thin film can be deposited using hydrazine. Top as deposited >96% resp after 500:1 HF >90% conformality.

Aluminum Oxide ALD with Hydrogen Peroxide: Comparative Study of Growth and Film Characteristics for Anhydrous H2O2‚ H2O2/H2O Mixtures‚ H2O and Ozone (LINK)

Jeffrey Spiegelman‚ Dan Alvarez (RASIRC); Keisuke Andachi‚ Gaku Tsuchibuchi‚ Katsumasa Suzuki (Taiyo Nippon Sanso Corporation‚ Japan)

Thermal low temperature ALD has seen a resurgence in activity due to difficulties found with plasma approaches on 3D surfaces. Hydrogen peroxide reactivity may benefit low temperature growth rates and achieve improved film properties. We studied:
  • Gas-phase hydrogen peroxide‚ delivered from an anhydrous‚ ampoule-based formulation by use of a membrane delivery system.
  • High concentration H2O2/H2O delivery by in situ concentration methods and use of a membrane vaporizer as a gas generator.
Composition of films grown by all four oxidant methods was measured by XPS; all films have near stoichiometric Al2O3 composition‚ within the experimental error of the instrument.

Dielectric Breakdown Strength measurement comparing films grown by all three oxidants. Hydrogen peroxide based film shows a significant increase in this electrical property where H2O2/H2O > H2O2 > O3 > H2O.
Initial wet etch rate studies (7.14% buffered HF) were performed on H2O2/H2O and H2O films grown at 200°C. In this instance‚ H2O2/H2O film has an etch rate of 69.9nm/min vs 81.5nm/min for water: a 15% improvement in etch resistance.
Electrical properties of resultant Al2O3 films have been examined. For films grown at 300C‚ Dielectric Breakdown Strength was measured. Here‚ film grown with H2O2/H2O was significantly greater than both water and ozone grown films; anhydrous hydrogen peroxide was similarly improved‚ but to a lesser degree. An analogous result was obtained when measuring leakage current.

Friday, June 26, 2020

Chemistry paves the way for improved electronic materials - LiU have developed a new molecule that can be used to create high-quality indium nitride

Indium nitride is a promising material for use in electronics, but difficult to manufacture. Scientists at LiU have developed a new molecule that can be used to create high-quality indium nitride, making it possible to use it in, for example, high-frequency electronics.

Rouzbeh Samii, Henrik Pedersen, Nathan O’Brien and Polla Rouf in the laboratory. Photo: Magnus Johansson

The bandwidth we currently use for wireless data transfer will soon be full. If we are to continue transmitting ever-increasing amounts of data, the available bandwidth must be increased by bringing further frequencies into use. Indium nitride may be part of the solution.

“Since electrons move through indium nitride extremely easily, it is possible to send electrons backwards and forwards through the material at very high speeds, and create signals with extremely high frequencies. This means that indium nitride can be used in high-frequency electronics, where it can provide, for example, new frequencies for wireless data transfer”, says Henrik Pedersen, professor of inorganic chemistry at the Department of Physics, Chemistry and Biology (IFM) at LiU. He has led the study, which was recently published in Chemistry of Materials.

Doctoral student Polla Rouf at the ALD reactor, used to create thin films of indium nitride. Photo: Magnus Johansson

Indium nitride consists of nitrogen and a metal, indium. It is a semiconductor and can therefore be used in transistors, on which all electronic devices are based. The problem is that it is difficult to produce thin films of indium nitride.
Thin films of similar semiconductor materials are often produced using a well-established method known as chemical vapour deposition, or CVD, in which temperatures between 800 and 1,000 ºC are used. However, indium nitride breaks down into its constituents, indium and nitrogen, when it is heated above 600 ºC.

In contrast with those investigated previously, the molecules investigated here contained nitrogen atoms where carbon atoms had previously been located. This gives a molecule with an indium atom in the centre, surrounded by three molecular fragments, where three nitrogen atoms form a “bridge” (a triazenide). Picture: Karl Rönnby

The scientists who conducted the present study have used a variant of CVD known as atomic layer deposition, or ALD, in which lower temperatures are used. They have developed a new molecule, known as an indium triazenide. No one had worked with such indium triazenides previously, and the LiU researchers soon discovered that the triazenide molecule is an excellent starting material for the manufacture of thin films.

Nathan O'Brien at the glove box in which the sensitive molecules are protected from air and moisture during synthesis. Photo: Magnus Johansson

Most materials used in electronics must be produced by allowing a thin film to grow on a surface that controls the crystal structure of the electronic material. The process is known as epitaxial growth. The researchers discovered that it is possible to achieve epitaxial growth of indium nitride if silicon carbide is used as substrate, something that was not previously known. Furthermore, the indium nitride produced in this way is extremely pure, and among the highest quality indium nitride in the world.

“The molecule that we have produced, an indium triazenide, makes it possible to use indium nitride in electronic devices. We have shown that it is possible to produce indium nitride in a manner that ensures that it is sufficiently pure to be described as a true electronic material”, says Henrik Pedersen.The researchers discovered another surprising fact. It is generally accepted among those who use ALD that the molecules should not be allowed to react or be broken down in any way in the gas phase. But when the researchers changed the temperature of the coating process, they discovered that there is not just one, but two, temperatures at which the process was stable.

“The indium triazenide breaks down into smaller fragments in the gas phase, and this improves the ALD process. This is a paradigm shift within ALD – using molecules that are not fully stable in the gas phase. We show that we can obtain a better final result if we allow the new molecule to break down to a certain extent in the gas phase”, says Henrik Pedersen.

The researchers are now examining similar triazenide molecules with other metals than indium, and have obtained promising results when using these to produce molecules for ALD. The study has been carried out together with researchers from the Swedish University of Agricultural Sciences in Uppsala and Carleton University in Ottawa, Canada. It has received financial support from the Swedish Foundation for Strategic Research (SSF) and the Knut and Alice Wallenberg Foundation. Principal author of the published article is Nathan O´Brien, research fellow in the Department of Physics, Chemistry and Biology.

The article: “In Situ Activation of an Indium(III) Triazenide Precursor for Epitaxial Growth of Indium Nitride by Atomic Layer Deposition”, Nathan J. O’Brien, Polla Rouf, Rouzbeh Samii, Karl Rönnby, Sydney C. Buttera, Chih-Wei Hsu, Ivan G. Ivanov, Vadim Kessler, Lars Ojamäe and Henrik Pedersen, Chemistry of Materials, published as an open access article on 24 April, doi: 10.1021/acs.chemmater.9b05171

Friday, June 19, 2020

Improved crystalline quality of Plasma ALD GaN ising plasma surface pretreatment

Semiconductor Today reports that Researchers based in China and the USA have improved the crystal quality of gallium nitride (GaN) thin films on sapphire from a 350°C low-temperature plasma-enhanced atomic layer deposition process (PE-ALD) using an in-situ bake and plasma substrate pretreatment.

Source: Baking and plasma-enhanced low-temperature gallium nitride atomic layer deposition, Moke Cooke, Semiconductor Today LINK

Journal Publicarion Sanjie Liu et al, Appl. Phys. Lett., vol116, p211601, 2020

Tuesday, June 16, 2020

ASM’S Korean partner receives US$4.5 million grant from Korean government for clean metals R&D (Zr, Hf, Nb, RE)

The Korean Government has awarded US$4.5 million in grants to ASM’s Korean R&D partner Zirconium Technology Corporation (ZironTech) to use to progress its commitment to the Joint Venture (JV) with ASM. The grants were awarded as part of the Korean Government’s US$5 billion Industrial Technological Program, led by the Korean Ministry of Industry, Trade and Resources as it seeks to establish clean metal supply independence and advance material technology for future market demand.

ZironTech has received funding for the development of a low emission, high purity metal refining technology that can be applied to zirconium, titanium, rare earths for permanent magnet alloys. This development is occurring in JV with ASM who has the exclusive rights to the commercialisation of the technology worldwide. The technology is intended to replace conventional energy-intensive metallisation processes with a more environmentally friendly, sustainable and cost-effective alternative.

Australian Strategic Materials Managing Director, David Woodall said: “We are pleased that both ASM and the technology we are developing in partnership with ZironTech has been recognised by the Korean Government as critical in its journey to ensuring sovereign supply for critical materials. The technology to produce critical metals adds value to our project and is key to the growth of Korea’s and Australia’s new technology and manufacturing sectors, with the strong government focus on increasing domestic production to secure supply stability.”

The JV between ASM and ZironTech is finalising the commissioning of its commercial pilot plant facility to produce these high-purity metals in parallel with developing the design for the world’s first commercial scale metal plant. This will help meet the growing demand for a new source into domestic and global markets for ASM’s range of high-purity and value-added critical metals – including zirconium, rare earth magnet metals (praseodymium and neodymium), niobium, and hafnium.

ASM is progressing the development of the Dubbo Project in Central West NSW, an advanced polymetallic project with large in-ground resource of zirconium, rare earth elements (including yttrium), niobium, and hafnium. This polymetallic project represents a strategic and independent supply of critical minerals for a range of sustainable technologies and future industries.

The Dubbo Project is development ready, subject to financing, with the mineral deposit and surrounding land acquired, all major State and Federal approvals in place and extensive piloting and engineering completed.

In March 2020, the Australian Government-owned Export Finance Australia (EFA) confirmed interest in assisting with financing ASM’s Dubbo Project, stating it closely aligns with the recently announced initiative by the Australian Government to develop its “Critical Minerals” sector.
ASM’s investment in downstream processing will improve the economics of its Dubbo Project as well as giving it an involvement in the wider commercialisation of a breakthrough technology.