Advancing the micromechanical characterization of silicon with a focus on high temperatures

Gerald Schaffar

doi:10.34901/mul.pub.2026.072

Advancing the micromechanical characterization of silicon with a focus on high temperatures

Titel in Übersetzung: Weiterentwicklung der mikromechanischen Charakterisierung von Silizium mit Schwerpunkt auf hohen Temperaturen

Gerald Schaffar

Lehrstuhl für Funktionale Werkstoffe und Werkstoffsysteme (425)

Publikation: Thesis / Studienabschlussarbeiten und Habilitationsschriften › Dissertation

43 Downloads (Pure)

Abstract

Silizium ist eines der bedeutendsten Materialien der heutigen Zeit. Seine Verformung unter Last ist für zahlreiche Anwendungen und Bearbeitungsschritte bedeutsam. Zum Beispiel ist die Raumtemperaturverformung relevant für abrasive Bearbeitungsschritte. Die Hochtemperaturverformbarkeit ist besonders belangvoll für Wärmebehandlungen, bei denen Plastizität vermieden werden muss um die Produktzuverlässigkeit und die Ausrichtung von Fotomasken zu gewährleisten. Zudem ist Silizium in Einkristallen hoher Güte verfügbar und daher geeignet als Modellmaterial zur Untersuchung von Verformungsmechanismen. Eine Vielzahl solcher Mechanismen wird in Silizium in Abhängigkeit der Belastungsbedingungen in Gang gesetzt. In dieser Arbeit wurden druckinduzierte Phasenumwandlungen, Verzwillingung und verschiedene Arten der Versetzungsplastizität untersucht. Entsprechend beschäftigt sich diese Arbeit mit diversen Themen wissenschaftlichen und industriellen Interesses.
Indentationsversuche bei Raumtemperatur widmen sich der Tieftemperaturplastizität von Silizium die von Hochdruckphasenumwandlungen dominiert wird. Diese können zur Entstehung von metastabilen kristallinen Phasen oder amorphem Silizium führen. Ein tieferes Verständnis dieser Umwandlungen ermöglicht die Anpassung der Entlastungsparameter, sodass umgewandeltes kristallines Silizium hoher Qualität entsteht, welches zu hexagonalem Silizium weiterumgewandelt werden kann – einem vielversprechenden Substrat zur Integration direkter Halbleiter auf Silizium.
Die Hochtemperaturversuche erweitern das Temperaturfenster für Mikromechanik auf Silizium auf bis zu 950 °C. Angewandt wurden drei Methoden zur Untersuchung der Hochtemperaturplastizität: Nanoindentation mit selbstähnlichen Berkovich-Spitzen, sphärische Nanoindentation und uniaxiale Mikrodrucksäulenkompression. Die sphärische Indentation wurde auf die Untersuchung polykristalliner Silizium-Dünnschichten angewandt, da sie das geeignetste Verfahren zur Messung deren Fließverhaltens ist. Die selbstähnliche Indentation und die Druckversuche wurden auf einkristallinen Substraten eingesetzt, um sich in ihren Ergebnisse zu ergänzen. Auch bei hohen Temperaturen ist Berkovich-Indentation ein verlässlicher Test, der auf einer glatten Oberfläche ohne aufwendige Probenfertigung durchgeführt werden kann. Zudem ist es ein vergleichsweise robustes Verfahren in Bezug auf Abweichungen im mechanischen Kontakt. Die multiaxiale Belastung erschwert jedoch die Analyse des Verformungsverhaltens. Hier ergänzt die uniaxiale Kompression. Die lithografisch hergestellten Proben sind deutlich aufwendiger zu fertigen, erlauben aber eine tiefergehende Interpretation und mikroskopische Untersuchung verformter Strukturen. In Summe wurde das Verständnis der Verformung mikroskopischer Siliziumvolumina von Normalbedingungen bis zu 950 °C durch unterschiedliche mikromechanische Methoden vorangetrieben.

Titel in Übersetzung	Weiterentwicklung der mikromechanischen Charakterisierung von Silizium mit Schwerpunkt auf hohen Temperaturen
Originalsprache	Englisch
Qualifikation	Dr.mont.
Gradverleihende Hochschule	Montanuniversität
Betreuer/-in / Berater/-in	Keckes, Jozef, Mitbetreuer (intern) Maier-Kiener, Verena, Betreuer (intern) Balila, Nagamani Jaya, Beurteiler B (extern), Externe Person Pippan, Reinhard, Beurteiler A (intern)
DOIs	https://doi.org/10.34901/mul.pub.2026.072
Publikationsstatus	Veröffentlicht - 2026

Bibliographische Notiz

nicht gesperrt

Schlagwörter

Silizium
Mikromechanik
Hochtemperatur
Plastizität
Phasenumwandlung

Zugriff auf Dokument

10.34901/mul.pub.2026.072Lizenz: CC BY

VolltextEndgültige, publizierte Fassung, 21,8 MB

Dieses zitieren

@phdthesis{e44910aa87db42d69f96591c19071fa5,

title = "Advancing the micromechanical characterization of silicon with a focus on high temperatures",

abstract = "Silicon is one of the defining materials of the current age. The deformation of silicon under load is of interest in several applications and processing techniques. Exemplarily, the room temperature deformation behavior is important in abrasive machining processes. The deformability at high temperatures is especially relevant for annealing processes where undesired plastification must be avoided to ensure device reliability and lithographic mask alignment. Additionally, silicon is readily available in high-quality single crystals and is therefore well-suited as a model material to study deformation mechanisms. An abundance of such mechanisms is triggered in silicon depending on the loading conditions. Studied here were pressure-driven phase transformations, twinning, and different types of dislocation plasticity. Accordingly, this thesis addresses several topics of academic and industrial interest. Indentation studies at room temperature delve into the low-temperature plasticity of silicon, which is dominated by a high-pressure phase transformation. They can lead to the formation of different metastable crystalline silicon phases or amorphous silicon. A better understanding of these transformations enables tailoring the unloading parameters to obtain transformed crystalline silicon of good quality and quantity, which can be further transformed to hexagonal silicon ¿ a promising substrate for integrating direct band gap semiconductors on silicon. The high temperature studies significantly expand the previously accessible temperature range for such small-scale experiments on silicon up to 950 °C. Three methods of assessing the high-temperature plasticity were applied: Nanoindentation with self-similar Berkovich tips, spherical nanoindentation, and uniaxial compression of micropillars. The spherical indentation experiments were applied to polycrystalline silicon thin films as the most suitable test to measure the flow behavior of such a structure. The self-similar indentation and uniaxial compression were used on monocrystalline substrates in a fashion where the experiments complement each other. Even at high temperatures, Berkovich indentation provides a reliable test that can be performed on a flat surface without elaborate sample preparation. Furthermore, it is comparably robust considering alignment and other contact deviations. However, the multiaxial loading makes the interpretation of the deformation behavior challenging. Here, uniaxial micropillar compression comes into play. The lithographically produced pillars are much more elaborate to produce, but provide the ability for more insightful interpretation and post-deformation microscopy. In total, the understanding of the deformation of microscopic volumes of silicon from ambient conditions up to 950 °C has been advanced by different micromechanical approaches.",

keywords = "silicon, micro mechanics, high temperature, plasticity, phase transformation, Silizium, Mikromechanik, Hochtemperatur, Plastizit{\"a}t, Phasenumwandlung",

author = "Gerald Schaffar",

note = "no embargo",

year = "2026",

doi = "10.34901/mul.pub.2026.072",

language = "English",

school = "Technical University of Leoben (000)",

}

TY - BOOK

T1 - Advancing the micromechanical characterization of silicon with a focus on high temperatures

AU - Schaffar, Gerald

N1 - no embargo

PY - 2026

Y1 - 2026

N2 - Silicon is one of the defining materials of the current age. The deformation of silicon under load is of interest in several applications and processing techniques. Exemplarily, the room temperature deformation behavior is important in abrasive machining processes. The deformability at high temperatures is especially relevant for annealing processes where undesired plastification must be avoided to ensure device reliability and lithographic mask alignment. Additionally, silicon is readily available in high-quality single crystals and is therefore well-suited as a model material to study deformation mechanisms. An abundance of such mechanisms is triggered in silicon depending on the loading conditions. Studied here were pressure-driven phase transformations, twinning, and different types of dislocation plasticity. Accordingly, this thesis addresses several topics of academic and industrial interest. Indentation studies at room temperature delve into the low-temperature plasticity of silicon, which is dominated by a high-pressure phase transformation. They can lead to the formation of different metastable crystalline silicon phases or amorphous silicon. A better understanding of these transformations enables tailoring the unloading parameters to obtain transformed crystalline silicon of good quality and quantity, which can be further transformed to hexagonal silicon ¿ a promising substrate for integrating direct band gap semiconductors on silicon. The high temperature studies significantly expand the previously accessible temperature range for such small-scale experiments on silicon up to 950 °C. Three methods of assessing the high-temperature plasticity were applied: Nanoindentation with self-similar Berkovich tips, spherical nanoindentation, and uniaxial compression of micropillars. The spherical indentation experiments were applied to polycrystalline silicon thin films as the most suitable test to measure the flow behavior of such a structure. The self-similar indentation and uniaxial compression were used on monocrystalline substrates in a fashion where the experiments complement each other. Even at high temperatures, Berkovich indentation provides a reliable test that can be performed on a flat surface without elaborate sample preparation. Furthermore, it is comparably robust considering alignment and other contact deviations. However, the multiaxial loading makes the interpretation of the deformation behavior challenging. Here, uniaxial micropillar compression comes into play. The lithographically produced pillars are much more elaborate to produce, but provide the ability for more insightful interpretation and post-deformation microscopy. In total, the understanding of the deformation of microscopic volumes of silicon from ambient conditions up to 950 °C has been advanced by different micromechanical approaches.

AB - Silicon is one of the defining materials of the current age. The deformation of silicon under load is of interest in several applications and processing techniques. Exemplarily, the room temperature deformation behavior is important in abrasive machining processes. The deformability at high temperatures is especially relevant for annealing processes where undesired plastification must be avoided to ensure device reliability and lithographic mask alignment. Additionally, silicon is readily available in high-quality single crystals and is therefore well-suited as a model material to study deformation mechanisms. An abundance of such mechanisms is triggered in silicon depending on the loading conditions. Studied here were pressure-driven phase transformations, twinning, and different types of dislocation plasticity. Accordingly, this thesis addresses several topics of academic and industrial interest. Indentation studies at room temperature delve into the low-temperature plasticity of silicon, which is dominated by a high-pressure phase transformation. They can lead to the formation of different metastable crystalline silicon phases or amorphous silicon. A better understanding of these transformations enables tailoring the unloading parameters to obtain transformed crystalline silicon of good quality and quantity, which can be further transformed to hexagonal silicon ¿ a promising substrate for integrating direct band gap semiconductors on silicon. The high temperature studies significantly expand the previously accessible temperature range for such small-scale experiments on silicon up to 950 °C. Three methods of assessing the high-temperature plasticity were applied: Nanoindentation with self-similar Berkovich tips, spherical nanoindentation, and uniaxial compression of micropillars. The spherical indentation experiments were applied to polycrystalline silicon thin films as the most suitable test to measure the flow behavior of such a structure. The self-similar indentation and uniaxial compression were used on monocrystalline substrates in a fashion where the experiments complement each other. Even at high temperatures, Berkovich indentation provides a reliable test that can be performed on a flat surface without elaborate sample preparation. Furthermore, it is comparably robust considering alignment and other contact deviations. However, the multiaxial loading makes the interpretation of the deformation behavior challenging. Here, uniaxial micropillar compression comes into play. The lithographically produced pillars are much more elaborate to produce, but provide the ability for more insightful interpretation and post-deformation microscopy. In total, the understanding of the deformation of microscopic volumes of silicon from ambient conditions up to 950 °C has been advanced by different micromechanical approaches.

KW - silicon

KW - micro mechanics

KW - high temperature

KW - plasticity

KW - phase transformation

KW - Silizium

KW - Mikromechanik

KW - Hochtemperatur

KW - Plastizität

KW - Phasenumwandlung

U2 - 10.34901/mul.pub.2026.072

DO - 10.34901/mul.pub.2026.072

M3 - Doctoral Thesis

ER -