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Plain Language Descriptions

Technological devices include computer microprocessors, memory devices, displays, cell phones, optical communications components, laser-based sensors and other devices, solar cells, electric vehicle batteries, fuel cells, and many more...

The dimensions (length, width, height) of these devices are typically between 1 and 100 cm. However, many of them work because of extremely tiny features and extremely thin films of different materials (e.g. metals, oxides, sulfides, nitrides, silicides etc.) which cannot be seen with the naked eye. For example, in a current computer microprocessor, the transistors at the heart of the microprocessor are so tiny that over 100 million of them could fit on the head of a pin! This means that current computer chips contain an enormous number of transistors, and this is what makes them so much faster and more powerful than microprocessors 10 or 20 years ago. Similarly, in NAND memory devices (e.g. USB drives and digital camera memory), each 'memory cell' is extremely tiny, and to fit more into a small device (so that it can store more information), they are extremely closely spaced and stacked in 3-dimensions, like apartments in a high-rise building.

This all sounds great…, but it means that devices such as microprocessors and memory devices are extremely difficult to make, and incredible advances in science and engineering have been required in order to make fabrication of these devices possible.

Key steps in the fabrication of these devices include deposition of an ultra-thin layer of a particular material, removal of parts of this layer using light to define a specific etching pattern, deposition of a layer of a different material, and so on. However, the films used in these devices must be extremely thin (often just a few nanometres), extremely uniform (i.e. their thickness hardly varies over the entire surface of the device), and extremely conformal (i.e. the film follows the contours of the surface of the device, even if the surface includes deep trenches, holes, or overhangs with nanoscale dimensions). This places extreme demands on the technologies used for thin film deposition, especially as future advances will require device features which are both smaller and more complex. In fact, many of the currently used materials and existing technologies will not be suitable to enable these advances, with the exception of an emerging technique named Atomic Layer Deposition (ALD).

ALD is a method used to deposit ultra-thin films of materials (e.g. films which are just a few nanometres thick), and the resulting films are more uniform and conformal than those accessible using any other industrially applicable technique. Consequently, ALD has many potential applications in the fabrication of technological devices, and also to fabricate catalyst materials for use in technological devices. In fact, it is widely acknowledged in the semiconductor industry as the only manufacturing method with the capabilities to meet future demands, and it is already used to deposit thin films in computer chips (HfO2), memory devices (Al2O3) and thin film displays (ZnS).

However, ALD is a chemistry-centric technique, which relies upon reactions between different pairs of molecules to deposit each different type of material (click here for more detailed information). Therefore, each target material requires a unique chemical reaction and at least one precursor molecule to be developed, and as a result, industrially-applicable ALD methods have yet to be realized for many of the required device-enabling materials.

Future advancements in ALD therefore require collaborations between chemists and engineers, where the chemists develop the molecules and reactions required to deposit the materials that the engineers require for device fabrication. This often requires the design and synthesis of new molecules (highly reactive ones) which have never existed before, and is a major focus for several of the research groups on the ALD-focused ORF grant.

Areas where ALD can enable major future advances include:

  • Faster and more reliable computers which require less resources
  • Memory devices with improved capacity, longevity and reliability
  • Faster and less expensive hardware to convert between electrical signals in a computer and light-based signals
  • Optical communications components for extremely rapid optical transfer of increasingly large amounts of data (as predicted to be required in the next 5-10 years)
  • New low-cost devices which rely upon infra-red laser components, including:

            -  devices for remote environmental monitoring
            -  laser sensors for use in self-driving vehicles
            -  medical instruments to remove diseased tissue

  • Devices and materials for a sustainable energy economy, where renewable sources of electricity (e.g. wind, solar, hydro) are harnessed to produce the fuels and chemicals that society depends upon, thereby reducing pollution and eliminating CO2 emissions. This could include:

            -  catalysts to convert carbon dioxide (utilizing renewable energy sources) into valuable fuels and chemicals
            -  catalysts to utilize renewable energy sources and water to produce the hydrogen required in fuel cells and industrial processes
            -  fuel cells for hydrogen-based transportation which are less-expensive, longer lived, and require fewer valuable resources (e.g. platinum)
            -  electric vehicle batteries with increased longevity, faster charging, and more consistent performance over a range of temperatures

These are all areas of technology which are urgently required in order to enable continued advancements in the technology that we rely upon in our daily lives, and ensure that energy and chemicals are generated using new technologies which are sustainable as well as profitable. They are major undertakings, although advancements at the nanoscale will be critical to success.

Overall, materials- and device-focused advancements in science and engineering hold the key to future advancements in technology and sustainability, and can undoubtedly yield positive environmental, societal and economic benefits.

Academic research in the development and application of new ALD precursor molecules and methods is also excellent training for future careers with a range of industries, including companies focused on:

  • developing, synthesizing and selling precursor molecules for thin film deposition
  • microelectronics (these companies use, develop and troubleshoot a broad range of thin film deposition processes)
  • thin film deposition reactors
  • electric vehicle batteries and fuel cells
  • fine chemicals and catalyst development
  • petrochemicals and plastics
  • the development of new display technologies
  • clean energy solutions
  • photonic device fabrication (for various applications)
  • the nuclear energy industry (due to shared reliance on glovebox techniques)


For more information on McMaster's ALD-focused ORF-RE project, click here.

For more information on McMaster's ALD reactors, click here.

Abbreviations
nanometre = 1 billionth of a metre (or 1 millionth of a millimetre)