A New Zr Precursor Enhances Wafer-Scale Zirconium Dioxide Films

A new class of Zirconium (Zr) precursor, featuring boratabenzene ligand, has been developed by a team led by Mohd Zahid Ansari at Yeungnam University, enabling the production of highly conformal ZrO2 thin films via Atomic Layer Deposition (ALD). This innovation, detailed in a recent study published in Science Advances, uses tris(dimethylamido)dimethylamidoboratabenzene zirconium and oxygen as reactants to achieve amorphous ZrO2 films at temperatures ranging from 150–350 °C on SiO2/Si substrates.

The new approach decouples the conventional ALD process, enhancing the deposition temperature window and achieving a growth per cycle of 0.87 Å, which surpasses previous methods using different Zr precursors. The films exhibit extreme conformality with complete step coverage, even on substrates with complex topographies, marking a significant advancement in semiconductor fabrication.

This development not only streamlines the manufacturing process by using O2 as a mild oxidant but also promotes safer and more efficient production methods. The films transition into nanocrystalline cubic ZrO2 upon annealing at 850 °C, enhancing their properties for potential use in high-temperature applications and as coatings for optical filters. The research team's breakthrough paves the way for next-generation semiconductor devices with improved performance and reliability.

The use of ZrO2 in DRAM helps in addressing several challenges associated with the miniaturization of memory devices. As device dimensions continue to shrink, traditional silicon dioxide (SiO2) used in older generations of DRAM becomes less effective due to increased leakage currents and decreased reliability. ZrO2, with its higher dielectric constant, allows for greater data storage capacity and improved efficiency without compromising the device's size or power requirements.

Source: New class of Zr precursor containing boratabenzene ligand enabling highly conformal wafer-scale zirconium dioxide thin films through atomic layer deposition - ScienceDirect

Watch again - Material development for MRAM and FRAM stacks at Fraunhofer IPMS-CNT

Material development for MRAM and FRAM stacks

Dr. Lukas Gerlich & Konrad Seidel (Fraunhofer IPMS - Center Nanoelectronic Technologies)

Today, data is the lifeblood disrupting many industries. The vast majority of this data is stored in the form of non-volatile magnetic bits in hard disk drives. This technology was developed more than half a century ago and has reached fundamental scaling limits that prevent further increases in storage capacity. New approaches are needed.

In the webinar, FRAM (Ferroelectric Random Access Memory) and MRAM (Magnetoresistive Random Access Memory) will be presented as two promising concepts for future ultra-low power memory technologies. Special attention will be paid to material development and fabrication on state-of-the-art industrial equipment for 300 mm wafers.

Watch now: Webinars - Fraunhofer IPMS

Previous Webinar: Fe- FET - A Memory Device for Maximum Integration, Konrad Seidel (IoT Components and Systems) Webinars - Fraunhofer IPMS

Hafnium, Zirconium: Australian Strategic Materials a step closer to completing commercial pilot plan

Recent semiconductor materials related trade issues between Japan and South Korea have led South Korea to secure alternative sourcing of photoresists and metals for their semiconductor industry. This includes essential minerals for hafnium and zirconium ALD precursors that are used in the manufacturing of DRAM and Foundry logic at SK Hynix and Samsung fabs.

Besides the tension with Japan, China's dominance in the supply of zirconium chemicals and materials has highlighted the additional risk in the critical materials supply change for its important semiconductor and high tech industries.

One such action has been setting up a pilot plant in South Korea for hafnium and zirconium metal in joint development with Australias Alkane and its subsidiary Australian Strategic Materials (ASM). The joint undertaking has now moved to the next phase for a commercial operation of a pilot plant as reported by Alkaine below.

Australian Strategic Materials a step closer to completing commercial pilot plan

Australian Strategic Materials (ASM), a wholly owned subsidiary of Alkane Resources is getting closer to completing the construction of a commercial pilot plant facility in South Korea that will enable critical metal oxides, including zirconium and hafnium, to be converted into metals in clean, carbon-free way.

As the Covid-19 pandemic continues to highlight weaknesses in critical minerals supply chains globally, ASM has confirmed in Alkane Resources' quarterly recently it has received interest in both potential future supply and partnership from a number of parties in South Korea and elsewhere. ...

Read more.

Read more about previous blog about the Alkane Dubbo project in New South Wales, Austrailia:

The Dubbo Project - The High-k mine in Dubbo, NSW Australia

Hafnium product breakthrough consolidates Dubbo Project business case

China’s water crisis stems the flow of zirconium and rare earths for global industries

Alkane Resources reports that zirconium oxychloride (ZOC) prices are up 40% since January 2017

A comparasion of Hafnium and Zirconium ALD precursor comparison

Here is a very nice review paper from Uwe Schröder and co-workers at NaMLab in Dresden on comparing Hafnium and Zirconium ALD precursors published in the past decades and the selection for mixed HfO2 and ZrO2 ALD high-k and ferroelectric applications.

HfxZr1 − xO2 thin films for semiconductor applications: An Hf- and Zr-ALD precursor comparison editors-pick

Journal of Vacuum Science & Technology A 38, 022402 (2020); https://doi.org/10.1116/1.5134135
Monica Materano, Claudia Richter, Thomas Mikolajick, and Uwe Schroeder

In the last few years, hafnium oxide (HfO2), zirconium oxide (ZrO2), and their intermixed system (HfxZr1 − xO2) have aroused more and more interest due to their outstanding properties in the frame of semiconductor applications. Different mixtures of these two sister materials, i.e., different Hf:Zr ratios in HfxZr1 − xO2 layers, as well as different crystal arrangements come with a wide set of structural and electrical properties, making this system extremely versatile. Starting from an amorphous layer, the different crystalline phases are easier to be targeted through subsequent thermal treatment. A correct understanding of the deposition process could help in obtaining films showing the addressed material properties for the selected application. In this paper, a comparison of Hf- and Zr-atomic layer deposition precursors is conducted, with the goal of depositing an almost amorphous HfxZr1 − xO2 layer. Material composition is tuned experimentally in order to address the properties that are relevant for the semiconductor industry. The observed trends are examined, and guidelines for applications are suggested. 

Growth per cycle for the most common HfO₂ metal precursors as a function of deposition temperature. Except for the Hf[N(CH₃)(C₂H₅)]₄ precursor used in this work, the data have been extracted from other sources. (Reference for HfI4-O2 is wrong, should read ref. 28.)

Atomic Layer Deposition of Emerging 2D Semiconductors, HfS2 and ZrS2, for Optoelectronics

Miika Mattinen from Prof. Mikko Ritala's group, University of Helsinki, reports the ALD growth of 2D HfS2 and ZrS2—the potential rivals of the hot favorite 2D semiconductors MoS2 and WSe2. 

Abstract: Semiconducting 2D materials are studied intensively because of their promising performance in diverse applications from electronics to energy storage and catalysis. Recently, HfS2 and ZrS2 have emerged as potential rivals for the commonly studied 2D semiconductors such as MoS2 and WSe2, but their use is hindered by the difficulty of producing continuous films. 

Herein, we report the first atomic layer deposition (ALD) processes for HfS2 and ZrS2 using HfCl4 and ZrCl4 with H2S as the precursors. We demonstrate the deposition of uniform and continuous films on a range of substrates with accurately controlled thicknesses ranging from a few monolayers to tens of nanometers. The use of semiconductor industry-compatible precursors and temperatures (approximately 400 °C) enables facile upscaling of the process. The deposited HfS2 and ZrS2 films are crystalline, smooth, and stoichiometric with oxygen as the main impurity. 

Source : Atomic Layer Deposition of Emerging 2D Semiconductors, HfS2 and ZrS2, for Optoelectronics

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By Abhishekkumar Thakur

China’s water crisis stems the flow of zirconium and rare earths for global industries

World Water Day on 22nd March highlighted some staggering facts about water shortages affecting much of the world’s population. While many Western countries take access to clean water for granted, growing water crises in other countries have world-wide consequences. For example, China is taking steps to secure its water resources, with severe impacts for global supply chains across multiple industries.

‘Our bodies, our cities and our industries, our agriculture and our ecosystems all depend on it,’ said UN Secretary-General António Guterres. 70-80% of all water consumption is for agriculture and energy production. Balancing the water needs of food and energy production is a challenge for many nations.

Water is also essential to mining, chemicals production, and manufacturing, industries which have long assumed ongoing, plentiful supply. This perception is changing as a deeper understanding of the water balance for each country reveals a different reality. Some countries, including China, are net water exporters: the water used to produce the goods and materials they export is higher than the water embodied in imports. Also, the production of exports often pollutes their waterways.

As water stress sets in, these countries have no choice but to change their production practices and trade balance, disrupting global supply chains. For the past five years, the World Economic Forum has ranked water crises in its top 5 global risks in terms of impact, yet most industrial companies seem oblivious to the risks to supply chains for themselves and their customers.

Some provinces have water resources on par with the Middle East. Source: CWR LINK 

Graphic media images of devastating floods from typhoons and other extreme weather events give the impression that China has plenty of water. In southern China, this is partially true, but it’s not so in the north. According to China Water Risk, the 11 driest provinces are in northern China. Home to 38% of the population, these provinces account for 36% of agricultural output, 47% of industrial output and 43% of GDP, yet have only 7% of the country’s water resources. With a population of around 100 million, Shandong province, for example, has only 250 m3 of water per person – less than most countries in the Middle East. Less than 500 m3 of water per person is considered a critical shortage.

To meet demand, the Chinese have been extracting groundwater at unsustainably high rates. The driest 11 provinces rely on groundwater for 28% of water needs, compared to just 13% for the 13 most water-secure provinces, which are mostly in the south. If business continues as usual, water demand will exceed supply by 2030. Chinese authorities are well aware of these issues and are moving responsibly to impose the ‘three red lines’: national water quotas set for 2015, 2020 and 2030. The Made in China 2025 policy promotes high-GDP low-water industries and China is continuing its ‘war on pollution’.

The implications for China’s chemicals industries and the supply chains that depend on them are profound. For example, China dominates global zirconium chemicals supply on which the world relies for: mobile communications, clean energy technologies, catalytic converters used in the automotive industry, jet turbines, bio-ceramic dental, knee, and hip implants, and waterproof and fire-resistant fabrics. But two-thirds of China’s zirconium chemicals production is located in the dry northern provinces, with 52% of capacity in parched Shandong.

Similarly, China has conquered more than 90% of the rare earths market. Rare earths have multiple applications in advanced technology for transport, information, and communications, defense and medicine. Most of China’s rare earths production occurs in Inner Mongolia, where water supply is also under stress, despite relatively low population density.

So, what happens when Chinese authorities reduce or withdraw water access for zirconium and rare earths production? Or when new anti-pollution laws impose severe remediation costs on producers? Severe impacts will be felt around the world unless alternative supplies of these critical materials can be found.

Fortunately, Australia has the opportunity to secure a strategic alternative supply of zirconium, rare earths and other essential elements, for 80+ years. The world-class Dubbo Project in central NSW has a water supply and licenses in place, and water efficiency measures include extensive recycling and optimization of product and waste streams. To progress the Dubbo Project to construction, Alkane Resources seeks a blend of financing from export credit agencies, strategic partners and equity and debt markets. Information for investors is available here 

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Guest Blog by Alister MacDonald, General Manager - Marketing, Alkane Resources