The latest material being researched the world over is Hafnium Oxide, whose incorporation will make
computer circuits denser, faster
and consume less power.
Sharath Ahuja reports.
Imagine 30 million transistors fitting on the head of a pin and then imagine transistors that can switch on and off approximately 300 billion times a second. This is not stuff from science fiction but real hardcore technology coming your way soon.
In one of the biggest advancements in fundamental transistor design, chip, scientists and chip manufacturers will use dramatically different transistor materials to build the hundreds of millions of microscopic 45 nanometers (nm) transistors inside the next generation processors. The material being researched the world over is Hafnium Oxide whose incorporation will make computer circuits denser, faster and consume less power.
Traditionally fashioned out of silicon, transistors are simple on/off switches that process the ones and the zeros of digital electronic data. The faster its transistors switch, the more efficient the chip. Making them smaller, cheaper, and faster and more energy-efficient has helped the industry to stick to the prediction of Intel's co-founder, Gordon Moore that the number of transistors on a chip would double roughly every two years.
Microprocessors now consist of millions of transistors connected together by specific patterns of copper wires. In transistors, current flows between two terminals, called 'source' and 'drain'. This current is controlled by the voltage at a third terminal, the 'gate'. For a transistor to switch efficiently, the gate needs to be isolated from source and drain by a thin piece of insulating silica, know as the dielectric.
As transistors shrink, the silica gate insulator thins to just a few atomic layers and this allows quantum tunnelling of electrons, leading to current leakage across the dielectric, producing a lot of heat and poor chip performance. Transistor gate leakage associated with the ever thinning gate dielectric material made of Silicon dioxide has been recognised by the chip industry as one of the most formidable challenges facing Moore's law in this decade. So, research groups worldwide are trying to replace the insulator with a material that has a higher dielectric constant than silica, and the new material is Hafnium Oxide.
According to Intel Co-founder Gordon Moore, "The implementation of high-k and metal materials marks the biggest change in transistor technology since the introduction of polysilicon gate Metal-oxide-Semiconductor (MOS) transistors in the late 1960's".
Leading from the forefront in the quest to make very thin films of Hafnium Oxide using specially patented precursor technology is Dr Anjana Devi and her team at the Ruhr University, Bochum, Germany.
Dr Anjana Devi, currently a professor at the Inorganic Chemistry Group, Institute for Inorganic Chemistry II at the Ruhr University, has been actively working on developing new metalorganic complexes that can be used as precursors for MOCVD (Metalorganic Chemical Vapour Deposition) and ALD (Atomic Layer Deposition) techniques that can be used for the deposition of thin films of Hafnium Oxide.
The newly developed precursors are then tested in the state-of-the-art industrial tool MOCVD and ALD reactors to grow thin films of Hafnium Oxide that can be eventually tested for device applications. Dr Anjana and her group have been successful in developing some novel metalorganic complexes of Hafnium. Their work has been cited in several prestigious scientific publications the world over. The February 2007 issue of Nano Science and Technology had prominently featured their work on thin films of Hafnium Oxide. The work being carried out by Dr Anjana and her group and many research scientists worldwide represents a major milestone as the industry races to reduce electrical current leakage in transistors - a growing problem for chip manufacturers as transistors get even smaller.
Dr Anjana Devi's research and development work in the frontier area of Hafnium Oxide thin films to be used as possible gate insulators for the chip industry has won her the Best Invention award from the Ruhr University in 2006. Dr Anjana's collaborative effort was patented together with a European company RUBITEC.
Giant chip manufacturers such as Intel and IBM have announced that they will use Hafnium doped materials to build smaller, faster transistors for their next generation chips, dubbed the 45 nanometer Transistor Technology.
Transistor technology has come a long way and new problems in science require new materials. The work carried out by scientists such as Dr Anjana Devi overcome a potentially crippling technical obstacle that has arisen as a transistor's tiny switches are made even smaller.
American Nobel Physicist Prof Richard Feynman, in his famous talk he gave on December 29, 1959 at the annual meeting of the American Physical Society at the California Institute of Technology said, "There’s plenty of room at the bottom.”