Browsing by Author "Laitinen, Mikko"

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  • Aluminum oxide/titanium dioxide nanolaminates grown by atomic layer deposition: Growth and mechanical properties
    (2017-01-01) Ylivaara, Oili M E; Kilpi, Lauri; Liu, Xuwen; Sintonen, Sakari; Ali, Saima; Laitinen, Mikko; Julin, Jaakko; Haimi, Eero; Sajavaara, Timo; Lipsanen, Harri; Hannula, Simo-Pekka; Ronkainen, Helena; Puurunen, Riikka
     A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
    Atomic layer deposition (ALD) is based on self-limiting surface reactions. This and cyclic process enable the growth of conformal thin films with precise thickness control and sharp interfaces. A multilayered thin film, which is nanolaminate, can be grown using ALD with tuneable electrical and optical properties to be exploited, for example, in the microelectromechanical systems. In this work, the tunability of the residual stress, adhesion, and mechanical properties of the ALD nanolaminates composed of aluminum oxide (Al2O3) and titanium dioxide (TiO2) films on silicon were explored as a function of growth temperature (110-300 °C), film thickness (20-300 nm), bilayer thickness (0.1-100 nm), and TiO2 content (0%-100%). Al2O3 was grown from Me3Al and H2O, and TiO2 from TiCl4 and H2O. According to wafer curvature measurements, Al2O3/TiO2 nanolaminates were under tensile stress; bilayer thickness and growth temperature were the major parameters affecting the stress; the residual stress decreased with increasing bilayer thickness and ALD temperature. Hardness increased with increasing ALD temperature and decreased with increasing TiO2 fraction. Contact modulus remained approximately stable. The adhesion of the nanolaminate film was good on silicon.
  • Cloud based wastewater treatment process performance monitoring system development and implementation
    (2017-01-09) Mikkola, Jussi
     Kemian tekniikan korkeakoulu | Master's thesis
    Cost of data collection and storage in industrial processes have reduced during the latest years, leading to a rapidly growing amount of data created. Due to the development of cloud based internet solutions this data is also possible to be available in a centralized and organized form. To be able to utilize the data efficiently, it has to be condensed into an informative form. This has already been executed in development of performance indicators that intend to indicate the true performance of a process by combining different parameters into a one value. The purpose of this thesis was to combine both technological advantages in today’s process automation and performance assessment technologies to design and implement a cloud based wastewater treatment process performance monitoring system. Both suitability of the used cloud based monitoring platform in calculation of performance indicators, and the suitability of the performance indicators in real time plant performance monitoring were measured. A literature study was conducted where the current state, trends and future design targets of industrial automation were found out. The concept of wastewater treatment plant performance assessment was described, and existing standards, guidelines and frameworks were listed. Furthermore existing implementations of performance monitoring systems in wastewater treatment plants were presented and analysed. Based on the literature study findings, an example performance indicator framework was designed consisting of context information, process and corporate performance indicator and process variable categories. The designed framework was implemented in an online platform, which was connected to a small municipal wastewater treatment plant during the thesis. The implementation proved the monitoring platform capable of calculating basic performance indicators and calculated process variables from raw data. Important design considerations based on unsuccessfully calculated performance indicators and process variables were also stated. The system was found out to shift plant operation towards future design targets in wastewater treatment automation found from the literature. Designed performance indicator framework was further considered as a useful resource in real time and long term performance assessment of a wastewater treatment plant. Main benefits from the implemented system were improved communication and transparency both internally and externally, better realization of the true process performance, better long term performance follow-up, and centralized remote access to the key process performance data.
  • Creating Business Plans in the Telecommunications Industry
    (1999) Oksanen, Sami
     Helsinki University of Technology | Master's thesis
    Diplomityössä tutkitaan, kuinka konsultointiyrityksessä laaditaan liiketoimintasuunnitelmia tietoliikenneteollisuuden yrityksille. Tutkimuksen tuloksia voidaan käyttää konsultointityössä, jossa yrityksiä autetaan laatimaan liiketoimintasuunnitelmia yksittäisinä projekteina. Valittu näkökulma rajoittaa tutkimusta, koska laatimista käsitellään ainutkertaisena tapahtumana. Diplomityössä on katsaus liiketoimintasuunnitelmista kertovaan kirjallisuuteen. Suunnitelmien laatimisoppaita, tutkimusartikkeleita ja kirjoituksia tietoliikenneteollisuudesta referoidaan ja arvostellaan valitusta näkökulmasta. Työssä käsitellään myös suunnitelmien hyödyllisyyttä yrityksille. Tietoliikenneteollisuuden liiketoimintasuunnitelmista havaitaan alalle tyypillisiä piirteitä, mutta todetaan myös, että tietoliikennealan yritykset saattavat toimia erilaisissa toimintaympäristöissä. Diplomityössä esitetään uusi liiketoimintasuunnitelmien laatimisprosessi, joka perustuu yleiseen malliin. Prosessissa mallista muokataan käytännöllinen viitekehys suunnitelmalle. Lisäksi prosessi näyttää, kuinka viitekehys auttaa suunnitelman laatimisessa, ja kuinka muut suunnittelun välivaiheet voidaan tehdä. Prosessin osia arvioidaan vertaamalla viitekehysmallia valmiisiin suunnitelmiin sekä laatimalla täysin uusi suunnitelma. Kasvavan konsultointiyrityksen täytyy hallita palvelutuotannonsa rakenne hyvin. Ohjeistetut tuotantoprosessit auttavat korkean laadun ylläpitämisessä sekä helpottavat myyntimäärän kasvattamista. Lisähyötyä saadaan, kun organisaation tiedot ja yhteiset taidot välittyvät tehokkaasti uusille työntekijöille. Tässä diplomityössä esitetään tapa, jolla konsultointiyritys voi tuottaa liiketoimintasuunnitelmia hallitulla tavalla.
  • Effect of ozone concentration on silicon surface passivation by atomic layer deposited Al2O3
    (2015) von Gastrow, Guillaume; Li, Shuo; Putkonen, Matti; Laitinen, Mikko; Sajavaara, Timo; Savin, Hele
     A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
    Abstract We study the impact of ozone-based Al2O3 Atomic Layer Deposition (ALD) on the surface passivation quality of crystalline silicon. We show that the passivation quality strongly depends on the ozone concentration: the higher ozone concentration results in lower interface defect density and thereby improved passivation. In contrast to previous studies, our results reveal that too high interface hydrogen content can be detrimental to the passivation. The interface hydrogen concentration can be optimized by the ozone-based process; however, the use of pure ozone increases the harmful carbon concentration in the film. Here we demonstrate that low carbon and optimal hydrogen concentration can be achieved by a single process combining the water- and ozone-based reactions. This process results in an interface defect density of 2 × 1011 eV−1 cm−2, and maximum surface recombination velocities of 7.1 cm/s and 10 cm/s, after annealing and after an additional firing at 800 °C, respectively. In addition, our results suggest that the effective oxide charge density can be optimized in a simple way by varying the ozone concentration and by injecting water to the ozone process.
  • Enhancing knowledge transfer in a small, knowledge-intensive organisation
    (1999) Nihti, Perttu
     Helsinki University of Technology | Master's thesis
  • Evaluation of different implementation scenarios for handling mobility in telecommunication networks
    (1994) Laitinen, Mikko
     Helsinki University of Technology | Master's thesis
  • Improving the lead time of product development by intensifying measurement process
    (2001) Viman, Janek
     Helsinki University of Technology | Master's thesis
  • Injection moulding simulation in mobile phone design process
    (1999) Kivelä, Jaana
     Helsinki University of Technology | Master's thesis
  • Parannettujen Galerkinin menetelmien soveltaminen konvektiivisten kulkeutumisongelmien mallintamiseen
    (1994) Laitinen, Mikko
     Helsinki University of Technology | Master's thesis
  • Plasma etch characteristics of aluminum nitride mask layers grown by low-temperature plasma enhanced atomic layer deposition in SF6 based plasmas
    (2012) Perros, Alexander; Bosund, Markus; Sajavaara, Timo; Laitinen, Mikko; Sainiemi, Lauri; Huhtio, Teppo; Lipsanen, Harri
     School of Electrical Engineering | A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
    The plasmaetch characteristics of aluminum nitride(AlN)deposited by low-temperature, 200 °C, plasma enhanced atomic layer deposition (PEALD) was investigated for reactive ion etch (RIE) and inductively coupled plasma-reactive ion etch (ICP-RIE) systems using various mixtures of SF6 and O2 under different etch conditions. During RIE, the film exhibits good mask properties with etch rates below 10r nm/min. For ICP-RIE processes, the film exhibits exceptionally low etch rates in the subnanometer region with lower platen power. The AlN film’s removal occurred through physical mechanisms; consequently, rf power and chamber pressure were the most significant parameters in PEALD AlN film removal because the film was inert to the SF+x and O+ chemistries. The etch experiments showed the film to be a resilient masking material. This makes it an attractive candidate for use as an etch mask in demanding SF6 based plasmaetch applications, such as through-wafer etching, or when oxide films are not suitable.
  • Thermomechanical properties of aluminum oxide thin films made by atomic layer deposition
    (2022-12-01) Ylivaara, Oili M.E.; Langner, Andreas; Ek, Satu; Malm, Jari; Julin, Jaakko; Laitinen, Mikko; Ali, Saima; Sintonen, Sakari; Lipsanen, Harri; Sajavaara, Timo; Puurunen, Riikka L.
     A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
    In microelectromechanical system devices, thin films experience thermal processing at temperatures some cases exceeding the growth or deposition temperature of the film. In the case of the thin film grown by atomic layer deposition (ALD) at relatively low temperatures, post-ALD thermal processing or high device operation temperature might cause performance issues at device level or even device failure. In this work, residual stress and the role of intrinsic stress in ALD Al2O3 films grown from Me3Al and H2O, O3, or O2 (plasma ALD) were studied via post-ALD thermal processing. Thermal expansion coefficient was determined using thermal cycling and the double substrate method. For some samples, post-ALD thermal annealing was done in nitrogen at 300, 450, 700, or 900 °C. Selected samples were also studied for crystallinity, composition, and optical properties. Samples that were thermally annealed at 900 °C had increased residual stress value (1400-1600 MPa) upon formation of denser Al2O3 phase. The thermal expansion coefficient varied somewhat between Al2O3 made using different oxygen precursors. For thermal-Al2O3, intrinsic stress decreased with increasing growth temperature. ALD Al2O3 grown with plasma process had the lowest intrinsic stress. The results show that ALD Al2O3 grown at 200 and 300 °C is suitable for applications, where films are exposed to post-ALD thermal processing even at temperature of 700 °C without a major change in optical properties or residual stress.
  • Use of Social Collaboration Tools in an Organisation
    (2016-10-31) Laitinen, Mikko
     Sähkötekniikan korkeakoulu | Master's thesis
    In this Master’s thesis I studied a global company’s social collaboration tool user preferences and usefulness. In this study I’ve scrutinized previous studies about social collaboration tools, choosing the tools and employee networks. The research material was gathered by interviewing a group of active and a group of random social collaboration tool users. The user preferences of these two social collaboration tool user groups were compared, and conclusions were made about how to get the random users to utilize the social collaboration tools more. In addition to this the current situation regarding the social collaboration tools in the company was examined: Are some type of tools missing? Are there useless tools in use? What type of tools are the most important? Suggestions are made in this study how to develop the social collaboration tools in the company. The conclusion is that the introduction to the use of the tools should be included as an integral part in the orientation program of new employees in the company, as well as guidelines for existing users should be promoted. In addition the tools should be constantly developed more functional, they should be integrated together better, and managerial support for social collaboration tools should be seamless in the organization. Lastly special emphasis should be placed on the promotion of the most popular social collaboration tool, as it is the tool that the greater part of social collaboration tools use.
  • Visuaalisen median katselukokemuksen immersiivisyys
    (2009) Laitinen, Mikko
     Elektroniikan, tietoliikenteen ja automaation tiedekunta | Bachelor's thesis