Development of two important Finnish innovations: Humicap and ALD Tuomo Suntola FROM MATERIALS PHYSICS TO NANOSCALE DEVICES – 50 YEARS OF FINNISH RESEARCH IN SEMICONDUCTOR TECHNOLOGY

Capacitive humidity sensor - Humicap Pre-study by Tapio Wiik: Capacitive humidity sensors had been demonstrated with porous Al 2 O 3 thin films and with polymer foil; Nylon foil humidity sensor was patented by Honeywell. The operational principle: Absorption of water vapor in a dielectric material result in an increase of the dielectric constant and the capacitance measured. Request to VTT Semiconductor laboratory by Vaisala Oy in 1971: “Development of a micro-sensor alternative for humidity measuring at weather stations and in radiosondes.” Tuomo Suntola started the development with Anja Savolainen as laboratorian in December The polymer line was selected: Instead of using a self supporting foil, the polymer material was dissolved in a solvent and a polymer film was formed on a glass substrate using a spinner (like used for photoresist in the lab) or by drawing up the substrate uniformly from the polymer solution. Jorma Antson joined the team in late summer 1972, the development was completed by the end of 1973.

Capacitive humidity sensor - Humicap + Nylon material was advantageous for having a low hysteresis. -The temperature and frequency dependence of the capacitance was substantial. A specific polymer material with linear response and practically zero temperature dependence was found Capacitance Relative humidity (%) Capacitance Relative humidity (%) With all polymers tested, the hysteresis was substantially lower in thin film structures than it was in self-supported foil structures.

Capacitive humidity sensor - Humicap The thin film structure comprised -Very fast response -Large temperature range -Low temperature dependence -Suitable for mass production A prototype sensor made in The sensor was fully functional when photographed in 2014.

Capacitive humidity sensor - Humicap As the world’s first thin-film capacitive humidity sensor, the HUMICAP ® was a radical innovation that completely changed the way humidity is measured. The new ground- breaking technology had no moving parts, and it was amazingly small due to the advanced use of thin-film technology. Today, Vaisala is the market leader in relative humidity measurements, and thin-film capacitive humidity sensors have developed from one company’s innovation into a global industry standard.

MEMS research activity, VTT From humidity sensor to EL-panels and ALD Request for proposals for new products Instrumentarium Oy Search for new challenges Late 1973 ”Humicap” humidity sensor to Vaisala Oy, Research unit Vaisala: Investment in IC-technology  Pressure sensors  Acceleration sensors VTI technologies 1991 Murata Electronics 2012 Okmetic

The proposal ? ? ? ? ? ? ? ? I am still confused … let’s go ahead Let’s develop an electroluminescent flat panel display EL …nobody has done it yet – but at a higher level Thin film technology, sensors, output devices Market research: -medical instrumentation, key components Lecture given on future displays at INSKO Request for proposals for new products

The problem and the solution State of the art: -High performance demonstrated -Major problems with stability due to the high operational voltage Novel thin film processing technique is needed Well order material requires well ordered processing conditions How about sequential buildup of compounds? May - June 1974 Well controlled electronic properties require well ordered material

The 1 st ALE process for ZnS, September th Baltic ALD, Helsinki Idea of sequential buildup of compounds, June 1974 Construction of a test equipment 10  torr 360  C 4x10  torr 3x10  torr 2x10  torr 2 c/s Zn S 320  C 100  C 0.4 mm minutes Hexagonal ZnS: monolayer 3.13 Å n=2.36 1/3 x monolayer Optical thickness monitoring

Need, ideas, solution, demonstration, basic patents Early ALD reactors EL demos

Need, ideas, solution, demonstration, basic patents Early ALD reactors EL demos Meeting the EL target Pilot production of EL panels Commercial production of EL panels, Lohja  Planar  Beneq Elcoteq Picopack

Need, ideas, solution, demonstration, basic patents Product prototypes, reactors for EL production Commercial production of EL panels, Lohja  Planar  Beneq Research for better understanding of ALD chemistry Microchemistry Ltd 40 years of ALD reactors commercial reactors

2004 Picosun Oy 2005 Beneq Oy Need, ideas, solution, demonstration, basic patents Product prototypes, reactors for EL production Commercial production of EL panels, Lohja  Planar  Beneq Research for better understanding of ALD chemistry Microchemistry Ltd 1999 ASM Microchemistry, commercial reactors & processes 40 years of ALD reactors commercial reactors

Helsinki University of Technology University of Joensuu 2004 Picosun Oy 2005 Beneq Oy Need, ideas, solution, demonstration, basic patents Product prototypes, reactors for EL production Commercial production of EL panels, Lohja  Planar  Beneq Research for better understanding of ALD chemistry Microchemistry Ltd, commercial reactors 1999 ASM Microchemistry, commercial reactors & processes From ideas to global industry th Conference on Solid State Devices and Materials Kobe, Japan ACSI conferences ALE-4 Linz 1996 The European SEMI Award 2004 was handed to Tuomo Suntola at the Munich Electronics Show 2004 by Stanley Myers, the President & CEO of SEMI (USA) “Honoring the Pioneer in Atomic Layer Deposition Techniques... that paved the way for the development of nanoscale semiconductor devices". Explosive increase in ALD activity - research & industrial Centre of Excellence

A Short History of Atomic Layer Deposition: Tuomo Suntola’s Atomic Layer Epitaxy By Dr. Riikka L. Puurunen, VTT Technical Research Centre of Finland, Espoo, Finland

Thank you for your attention! FROM MATERIALS PHYSICS TO NANOSCALE DEVICES – 50 YEARS OF FINNISH RESEARCH IN SEMICONDUCTOR TECHNOLOGY