Dr Tuomo Suntola is the creator of one of the most critical technologies in electronic devices today, but his nanosized brainchild is invisible to the millions of users who rely on it.
The Finnish physicist is the inventor of ALD (atomic layer deposition), the method of manufacturing the high-performing, ultra-thin films used in almost all computers and smartphones, microprocessors and digital memory devices.
The nanoscale invention has been a key factor behind the endurance of Moore's Law, which is the idea that the number of transistors on microchips will double every two years, dramatically increasing in power while reducing in cost to continually create smaller, more powerful, and cheaper computing power.
"The most important use of ALD is semiconductor processing," Dr Suntola tells Techworld. "ALD has made it possible to enter nanometer scale - modern microprocessors may have more than 10 billion transistors on a silicon chip the size of the thumbnail."
Suntola developed ALD in the 1970s but had to wait decades before his creation became ubiquitous in electronic devices.
The demand exploded in the 1990s when the semiconductor industry was reaching the limits of the component density it could produce in integrated circuits using conventional processing techniques. ALD allowed them to produce microelectronics of accurate thicknesses, uniform surfaces and high-quality film that would prevent leakage on silicon chips.
"Timing was fortunate because at that time there were machinery and processes for demonstrating ALD and its capability for atomic level control of material layers on silicon wafers," says Suntola. "Semiconductor processing is very demanding; it still took several years to get from the demonstration level to the industrial level – both regarding the machinery and the processes."
Turning experiments into applications
Suntola was born in Tampere in southern Finland in 1943 and he grew up as the country was recovering from the second world war, and rapidly industrialising.
He built wooden replicas of second world war fighter aircraft as a child and then progressed to radios and amplifiers in his teens before entering university. He earned a PhD in 1971 in Electron Physics at Helsinki University of Technology and then began a career in materials sciences and thin film technologies.
At the time, Finland's post-war industrialisation was shifting from heavy industry towards technology, earning a reputation as a "Nordic Japan". At the forefront of this transition was the formation of the Nokia Corporation in 1967 and its rapid rise to become an electronics giant, while Suntola was developing the technology that decades later would power the company's phones.
In 1973, he created his first industrial application: a humidity sensor called the Humicap, which measures and controls humidity in construction, manufacturing, food production and protects sensitive materials in museums, archives and warehouses. It remains a market leader in humidity sensing today.
Suntola's success convinced Instrumentarium, a Finnish medical devices manufacturer, to invite him to lead a research unit in the company, where he started to develop ALD as a method to replace bulky hospital monitors with electro-luminescent flatscreens.
"The success of Humicap gave me the necessary credibility for the start of the exotic electroluminescence and ALD developments," says Suntola. "The development of the electroluminescent display technology to the industrial level and then the development and implementation of ALD for new applications occupied most of my professional career."
Existing technologies struggled to create the quality of thin films required for these displays, so Suntola decided to develop a way that he could make them himself. One day, he was looking at the periodic table of elements hanging on his office wall and thinking about nature's simplicity when he got the idea for ALD, as a method of adding the complementary elements of a compound one by one onto a surface.
The nanoscale technology allows complex, three-dimensional structures to be built one atomic layer at a time to construct the ultra-thin material layers used in practically every modern smartphone or computers, as it helps them become smaller and less expensive while growing more powerful.
The invention was first patented in 1974, but it was almost ten years before the technology began to be commercialised.
"The first step was to analyse the theoretical demands and construct a test setup for demonstrating the build-up of material by atomic layers," says Suntola. "The very first experiment was successful, but it was years of work to develop machinery that fulfils both the chemical and productional demands necessary for industrial processing of ALD thin films."
In 1983, the first major proofs-of-concept of the displays were unveiled, on the information boards in the departure hall at Helsinki-Vantaa airport. The electroluminescent panels proved extremely reliable, keeping the boards running continuously for 15 years without a single character module requiring replacement.
In the end, Liquid Crystal Display (LCD) technology supplanted the ALD as the common technology behind flat-screen TVs, but the technique is still used for some screens in severe conditions.
"The key was the well-ordered material of the ALD thin films," says Suntola. "In semiconductor processing, the key characteristics of ALD are the precise, atomic level thickness control and the control of the material composition, and importantly, conformal coating feature which means that material layers can be formed on complex surfaces in three dimensions."
Gradually, the semiconductor industry began to recognise the value of ALD. In 2007, Intel became the first manufacturer to use ALD in its chips. Today, every major chip manufacturer uses a form of the technique.
Moore's Law and the universe
ALD has helped Moore's Law endure for more than 50 years, but the prediction may not prove true for much longer as the cost of shrinking transistors is becoming prohibitive.
"Moore's Law has worked surprisingly well for decades, although we did not know until later the technologies that made it work," says Suntola. "We are now approaching physical limits both in layer thicknesses and component densities. Maybe, again, new solutions are different from what we can imagine today."
ALD's future appears more secure. Research shows that the thin films have promising applications in medical instruments, implants, solar panels, LED lights, environmentally friendly packaging and electric car batteries.
"ALD can be used for improving the performance of solar cells and lithium batteries," says Suntola. "ALD thin films are used as protecting layers in OLED display devices, silver ornaments, and even telescope mirrors. ALD is excellent for bio-barriers for hermetic encapsulation and passivation of critical electronics in implantable micro-medical devices for, for example, cardiological and neurological treatments."
In 2018, Suntola's invention won him the 2018 Millennium Technology Prize, the world's largest technology award. Previous winners include World Wide Web inventor Tim Berners-Lee and Linux kernel creator Linus Torvalds.
"The extremely thin isolating or conducting films needed in microprocessors and computer memory devices can only be manufactured using the ALD technology developed by Tuomo Suntola," the Technology Academy Finland, which awards the biennial prize, said in a statement.
With the future of ALD assured, Suntola has shifted his focus to understanding nature by linking time and space. In 1995, he published a book titled "The Dynamic Universe (DU) – toward a unified picture of physical reality", which expounded his theories.
"The breakthrough occurred in the 1990s, when I realised that relativity appears as a direct consequence of the conservation of total energy in space, once we replace the four-dimensional spacetime coordinate system of the theory of relativity with universal scalar time and a metric four-dimensional coordinate system, which enables a dynamic analysis of whole space as a spherically closed energy system," he says.
"DU is like a second Copernican revolution, not just for the planetary system but for entire space. It means a major change in the paradigm but a significant simplification of the theory, and most importantly, an understandable picture of reality.”
Physicists have been slow to embrace his theory, but Suntola is comforted by the knowledge that groundbreaking ideas always face early resistance.
"I am now in a process to introduce the theory to serious scientific debate," he says. "The Copernican breakthrough took more than 100 years, we will see if we can do it faster with DU."