1. From the Basics to Industrial Applications
Opening Symposium of Global Innovation Center, Kyushu University – Friday, April 7th, 2017
From the Basics to Industrial Applications
Dr. Tuomo Suntola Picosun Oy, Finland
First, I like to thank the representatives of Kyushu University and the Global Innovation Centre for the honor and challenge to speak to the distinguished audience in this important and unique event.
1. I will start with a short description and history of the Atomic Layer Deposition process as an example of a long-term innovation process,
2. Second, I will – more generally – have a look to the key factors behind a successful innovation process.
Atomic Layer Deposition as a Long-term Innovation Process
Key Factors for Success in Innovation Processes

2. The problem and the solution
Opening Symposium of Global Innovation Center, Kyushu University – Friday, April 7th, 2017
The problem and the solution
State of the art in 1974:
High performance demonstrated
Major problems with stability due to the high operational voltage
Well controlled electronic properties require well ordered material
Well order material requires well ordered processing conditions
We often think that important developments are trigged by more or less, spontaneous ideas enabling new solutions or products. I think, that the most important trigger, however, is the identification of a real need, which motivates and focuses our thinking to necessary solutions to fulfil the demand.
In the 1970s, flat TV-screens and information displays were just a future dream.
In the beginning of 1974, I was faced the challenge of developing a flat panel display to medical instruments – with high contrast, high viewing angle and any other desirable properties. I found the electroluminescence technology as the most promising for that demand; an electroluminescent display is a full solid state device, and it is based on thin film technology which was my expertise area.
Some promising results with EL-panels had been demonstrated by Sharp Corporation in Japan, however, there was a major problem with the quality of the necessary thin films, which had to sustain the high operational voltage of about 200 volts across the thin film structure of 1 micron in thickness.
Based on my earlier work on amorphous thin films, I concluded that
- well controlled electronic properties require well-ordered material
- and, that well-ordered material requires well-ordered processing conditions
- obviously, we need novel processing technique for producing the necessary thin films
Happily, this basic thinking occurred when our thin film laboratory was under construction – the only tool that was available, was the table of chemical elements hanging on the wall in front of me. While looking at the periodic table, I came to the idea of utilizing the natural symmetry in chemical compounds: the active material in the EL device is zinc sulphide which is the compound group II zinc and group VI sulphur. How about creating conditions where the elements are supplied on the surface one at a time thus allowing a controlled buildup of the crystalline structure of the thin film material – and let nature accept one atomic layer at a time.
Novel thin film processing technique is needed
How about sequential buildup of compounds?
May - June 1974

3. Conventional thin film technologies
Opening Symposium of Global Innovation Center, Kyushu University – Friday, April 7th, 2017
Conventional thin film technologies
Vacuum evaporation
Sputtering
CVD
Heat treatment
Nucleation
Final crystallization
Let’s look at an overview of traditional thin film technologies:
In vacuum evaporation and sputtering, the compound is removed from the source by heating the source or by ion bombardment of the source material – and transferred to the substrate surface through vapor phase. The vapor is then condensated onto the substrate surface where a polycrystalline film is formed through a nucleation process.
In the case of Chemical vapor deposition (CVD) the compound is formed through a chemical reaction on the substrate surface, but the nucleation mechanism is essentially the same as it is in vacuum evaporation and sputtering. Very often the crystallization is still completed with a heat treatment.

4. The ALD sequences for compound AB
Opening Symposium of Global Innovation Center, Kyushu University – Friday, April 7th, 2017
The ALD sequences for compound AB
Substrate surface
Introduction of precursor 1 supplying element A of compound AB
Completed monolayer of element A
Introduction of precursor 2 supplying element B of compound AB
Completed monolayer of element B
In the Atomic Layer Deposition process, there are no free molecules nucleating on the surface. Each element is supplied onto the substrate one at a time – at a temperature preventing the condensation of the element – only the atoms finding a compound bond at the surface are able to stay – such a reaction is saturated as soon as a monoatomic layer of the first element of the compound is created on the surface.
In the second sequence the second element is supplied to react with the first layer formed. – Again, the reaction continues until the surface is covered with a monolayer of the second element.

5. The ALD sequences for compound AB
Opening Symposium of Global Innovation Center, Kyushu University – Friday, April 7th, 2017
The ALD sequences for compound AB
Substrate surface
Introduction of precursor 1 supplying element A of compound AB
Completed monolayer of element A
-reduced monolayer density
Introduction of precursor 2 supplying element B of compound AB
Completed monolayer of element B
-reduced monolayer density
In fact, the surface phenomenon is a little bit more complicated. The surface saturation occurs as described, but due to a surface re-construction process, the co-ordination of the surface atoms, we typically obtain one half or one third of a full monolayer in a reaction sequence.

6. The ALD sequences for compound AB using exchange reactions
Opening Symposium of Global Innovation Center, Kyushu University – Friday, April 7th, 2017
The ALD sequences for compound AB using exchange reactions
AY2
BX2 XY XY
Substrate surface AY
Introduction of precursor BX2 for supplying element B of compound AB(X), removal of X as XY
Completed AB(X) surface
Introduction of precursor AY2 supplying element A of compound AB(Y), removal of Y as XY
Completed compound AB(Y) monolayer
In most cases, it is advantageous to use compounds of the elements of the final compound as the reactants – such a choice essentially widens the scope of materials to be processed, and gives variety to favorable process conditions. For example, in many semiconductor applications we have limits to maximum temperatures to be applied.
Large ligands from a compound precursor may reduce the surface coverage percentage which, however, does not disturb the surface control mechanism.
Anyway, in the ALD process, we create favorable conditions for nature to take care of the buildup of highly ordered material, which – at a macroscopic scale – means automatic thickness control: we only need to calculate the number reaction cycles.

7. Thickness and structural perfection
Opening Symposium of Global Innovation Center, Kyushu University – Friday, April 7th, 2017
Thickness and structural perfection
From Atomic Layer Epitaxy to Atomic Layer Deposition
Greek language: ”epi - taxis”
= ”On arrangement”
Source control
Surface control
We may say, that the traditional thin film technologies are processes of material transfer from the source to the substrate – whereas the ALD process is a surface controlled process. In source controlled processes, the thickness of the film is proportional to the flux density of the source material hitting onto the surface. – In the ALD process, the surface is uniformly filled provided that the flux is enough to give the full coverage.
In order to emphasize this difference, originally, I named the process “Atomic Layer Epitaxy” – in Greek language epi-taxis means “on arrangement” which, in principle describes well the surface control mechanism. Professionals in traditional silicon technology, however, had fixed the use of term “epitaxy” to the narrow meaning of the growth of single crystals. For avoiding confusion the term “Atomic Layer Epitaxy” was replaced by “Atomic Layer Deposition” when the process was introduced to silicon technology.

8. Atomic Layer Deposition
Opening Symposium of Global Innovation Center, Kyushu University – Friday, April 7th, 2017
Atomic Layer Deposition
substrates
precursor feeding tubes
heating elements
The surface saturation mechanism requires some specific features in the reactors used to run the process. The source materials are supplied to the reaction zone sequentially from different feeding tubes – one at a time, each sequence separated by a purge phase.
The saturation mechanism allows material feed even through narrow spacings between the substrate surfaces to be covered. In such an arrangement reactant molecules hit many times the surfaces to be covered, which leads to a high material utilization efficiency. Such a design enables batch-type processing with multiple substrates in a small volume.

9. Conformal layers by ALD
Opening Symposium of Global Innovation Center, Kyushu University – Friday, April 7th, 2017
Conformal layers by ALD
Due to the surface control, ALD produces conformal material layers following the shape of the substrate surface, which enables processing of 3-dimensional structures and even the pores of porous materials.
The atomic level control enables nanometer scale tailoring of material layers:
The picture in right lower corner illustrates such a “nanolaminate” – still following the curved shape of the substrate.
~100% conformal ZnO:Al in deep trench with AR=60, deposited in a Picosun reactor. Source: VTT 2010

10. Quantum chemical analysis of ZnS ALD-sequences
Opening Symposium of Global Innovation Center, Kyushu University – Friday, April 7th, 2017
Quantum chemical analysis of ZnS ALD-sequences
ALD takes chemistry into atomic level which, for example, enables quantum chemical analysis of the material buildup – and turn chemistry into physics.
This picture shows the quantum chemical analysis made for the atomic layer buildup of zinc sulfide (ZnS) from zinc chloride and hydrogen sulphur as the precursors. In the picture on the left a full monolayer coverage in built in two reaction cycles of the precursors – in the picture on the right a full monolayer coverage is obtained in three cycles.
Chemistry at atomic level comprises expertise both in chemistry and physics – and opens new opportunities for the tailoring of molecular structures. It is a new opportunity in materials sciences and an educational challenge – to include quantum mechanics in chemistry and/or to include chemistry in physics studies.

11. ALD for electroluminescent displays
Opening Symposium of Global Innovation Center, Kyushu University – Friday, April 7th, 2017
ALD for electroluminescent displays
Today’s ALD has its roots for 40 years back. As stated in the beginning of my talk, everything was started from the need to defect-free high quality thin films for electroluminescent (EL) flat panel displays.
It took about five years from the idea of the ALD to EL prototypes, and another five years to the industrial production of the devices.
EL did not become a major display type, but it is still used in special applications in very severe conditions like at very low temperatures or under strong mechanical shocks or vibration. The production continues still in the factory built in the 1980s near Helsinki in Finland.
Commercial production of EL panels
Pilot production of EL panels
Product prototypes, reactors for EL production
Need, ideas, solution, demonstration, basic patents

12. ALD reactors – breakthrough of ALD technology
Opening Symposium of Global Innovation Center, Kyushu University – Friday, April 7th, 2017
ALD reactors – breakthrough of ALD technology
1994
2004 Picosun Oy
Microchemistry Ltd
1999 ASM Microchemistry
The need for atomically controlled material layers has become an essential demand in modern semiconductor manufacturing - and a necessity in nanoscale devices. Semiconductor processing has been a major challenge to the design of the ALD tool, the ALD reactor.
The first generation of ALD-reactors was designed for EL-display manufacturing. The second generation carried out in Microchemistry Ltd, in Finland, was directed to ALD-process and chemistry research and to semiconductor processing.
ALD for semiconductor applications was introduced in the MRS 1994 conference and exhibition in Boston, which meant a breakthrough in the ALD technology. Semiconductor industry and equipment manufacturers became involved. Microchemistry was acquired by the Dutch ASM in 1999 and Picosun Oy was established to continue the reactor development in Finland in 2004.
Semiconductor manufacturing meant new challenges in the material selection and perfection of the material layer quality. A top achievement is the plasma-ALD reactor, comprising Picosun’s ALD and Hitachi High-Technologies’ very advanced plasma technology.
Commercial production of EL panels
Product prototypes, reactors for EL production
Need, ideas, solution, demonstration, basic patents

13. Certain important materials for high performance semiconductor devices are difficult to produce with the basic ALD process. In general, due to ion bombardment, the use plasma activation in an ALD process is a risk for the perfection of the material layer formed.
Plasma in Hitachi High-Technologies’ plasma generator is generated in Microwave Electron Cyclotron Resonance chamber which is integrated to Picosun’s ALD reactor at a low pressure – enabling a kind of soft plasma activation in the ALD process allowing very high quality material buildup.
In the silicon nitride process, in the first sequence the surface is saturated with the silicon precursor – in the second sequence nitrogen plasma releases the precursor ligands and creates a monolayer of silicon nitride on the substrate.

14. The MOS elements – nanotechnology
Opening Symposium of Global Innovation Center, Kyushu University – Friday, April 7th, 2017
The MOS elements – 1970’s
The MOS elements – 1980’s
The MOS elements – 1970’s
The MOS elements – nanotechnology
The increase of the challenges in chemistry can be illustrated by the coverage of elements in the periodic table.
- In the 1970s the number of elements used was quite limited - in 1980s a little bit increased
- and today most part of the table is covered.
Source: P. Gargini, International Technology Roadmap for Semiconductors

15. Moore’s law for the complexity of IC’s
Opening Symposium of Global Innovation Center, Kyushu University – Friday, April 7th, 2017
Moore’s law for the complexity of IC’s
Introduction of ALD
ALD contribution to Moore’s law
2x /2 years
This figure shows the famous Moore’s law applied to the complexity of integrated circuits. The horizontal axis shows the years from 1960 to 2030 and the vertical axis the number of active components in an integrated circuit.
ALD was introduced to semiconductor manufacturing in mid 1990s – it took still about 10 years before ALD contributed to the complexity and performance of integrated circuits and discrete semiconductor devices like high frequency transistors.
The complexity of microprocessor circuits has increased by the factor of two in every two years. For the last ten years ALD has been an enabling technology for the continuation of that increase. Last week Intel announced the transistor density of their 10 nanometer technology which confirmed the continuation of the “doubling per two years” increase. ALD is needed, for example, for the control of the material composition and thickness of the gate dielectric, as well as to perform the conformal coverage.
From 1960 to 1970, ‘complexity’ is the number of components as initially described by Moore. After 1970, it was often cited as the number of bits in a DRAM or the number of transistors in a microprocessor. Source: Semiconductor International

16. Factors behind success
Opening Symposium of Global Innovation Center, Kyushu University – Friday, April 7th, 2017
Factors behind success
ALD Superlattice by NEC, 1985
The working environment
Identifying a real need to be worked on
Understanding of the problem
Understanding of the related phenomena
Understanding of the whole realization process
The working environment
Identifying a real need to be worked on
Understanding of the problem
Understanding of the phenomena behind the solution
Understanding of the whole realization process
What are the factors behind a successful innovation process?
The ALD development serves as an example of a demanding long-term innovation process. It was trigged by a well-defined problem behind a specific application. The usability of the ALD was first proven in the targeted application.
Today the basic idea behind the ALD – material buildup by atomic layers – is more like obvious, and a natural choice. The reactions to the idea of the ALD after my first conference presentation in a crystal growth conference in 1981 in San Diego were mixed.
There were scientists who immediately understood the new challenges. One of those was professor Jun-ichi Nishizawa, who trigged activity on ALD for III-V single crystal epitaxy in Japan in the mid 1980s.
- A top demonstration of the Japanese 1980s activity was the superlattice demonstration demonstrated by NEC. In the picture, you may distinguish eleven molecular layers of gallium-arsenide between indium-gallium phosphide – made with eleven ALD cycles.
Most scientists in the 1981 conference thought that building of material by atomic layers is not practical – even if possible, it must be far too slow for any industrial use. In fact, there were some recognized thin film experts who argued that ALD is impossible – they could not consider controlling of chemistry at atomic level. After a view mounts from the conference I received a letter and laboratory report from a professor in the field who explained that he has shown that ALD is impossible. At that time, we already had the process in pilot production of the EL displays – so, it was not necessary to start arguing against the claims.
So, let’s go to the factors of success: First, I like to mention the working environment,
The working environment in a small country like Finland is quite different from that in Japan with strong international high-tech industry and powerful research institutes.
- Whatever is the working environment, I cannot underestimate the importance of the identification of a real need to be worked on. Human people are motivated to work on things that they feel important and necessary. I feel that high motivation is a key for releasing and directing our imagination and intuitive powers which are necessary for novel findings.
- Once a real need is identified and a target set, it is important to acquire a thorough understanding of the problem or problems.
- For understanding the problem, we need to understand the phenomena behind the problem. The phenomena may fall into the scope of chemistry, physics, mechanics, engineering or somewhere between. It is very challenging to acquire a holistic view in order to start solving the right problems. In many cases our scientific knowledge is specified in narrow sectors with minor interchange with neighboring sectors. In his Nobel lecture in 1911, Wilhelm Wien reminded that “in science, the redeeming idea often comes from an entirely different direction, investigations in an entirely different field often throw unexpected light on the dark aspects of unresolved problems.”
- Finally, for managing demanding development and innovation processes it is important to understand the whole realization process. It is not only question of scientific and technological skills, but also the commercial and social issues related to the process.
I have emphasized “understanding” in each step of an innovation process. Sometimes it may be much more fruitful to sit down and think for a while – or even for quite a while – rather than entering right away to actions or experimentation.

17. Timespan of developments
Opening Symposium of Global Innovation Center, Kyushu University – Friday, April 7th, 2017
Timespan of developments
1000s of years 100s of years 10s of years Years Months
New models of products
New generations of products
Technologies behind manufacturing
Basic research for technology and application opportunities
When looking around, we see that the world is changing at an accelerating speed. New models of mobile phones appear almost every month.
For managing the time spans of different developments, it is useful to recognize the – may be invisible – parallel works behind any development:
- New models of products may enter in moths
- The development of new generations of products need typically years
- New technologies behind manufacturing, like the ALD technology, may need tens of years’ development
- Also, basic research behind technology and application opportunities may also extend to tens of years
- Understanding of the laws of nature and the refinement of the knowledge into fundamental theories have taken hundreds of years
- And finally, our cultural heritage and the understanding human nature behind all our activities may extend back to thousands of years. Still it is present in our daily thinking and decisions.
Understanding of the laws of nature and refinement of those into theories
Cultural heritage, understanding human nature

18. Thank you for your attention!
Opening Symposium of Global Innovation Center, Kyushu University – Friday, April 7th, 2017
Thank you for your attention!
With my best wishes for the success of the Global Innovation Center !
Thank you for your attention
– With my best wishes for the success of the Global Innovation Center!