氏名　金　弘大
学位の種類　博士（工学）
学位記番号　博甲第557号
学位授与の日付　平成22年8月31日
学位論文題目　Surface Control and Sintering Behavior of the Fine-structured Ceramics Sintered Body　（セラミックスの表面微細構造成型手法および焼結挙動に関する研究）
論文審査委員
　主査　教授　末松　久幸
　副査　教授　小松　高行
　副査　教授　植松　敬三
　副査　准教授　岡元　智一郎
　副査　准教授　中山　忠親
　副査　大阪大学名誉教授　新原　晧一

• 論文目次
• 論文要旨
• 論文審査の結果の要旨

［平成22（2010）年度博士論文題名一覧］ ［博士論文題名一覧］に戻る．

Table of Contents　p.i
CHAPTER 1　Introduction
　1.1　Necessities of develop ceramic nanoimprint methods　p.1
　1.2　Known methods and processes to fabricate fine-structured ceramic patterns　p.3
　1.2.1　Direct writing methods　p.3
　1.2.2　Downsizing mechanical processing methods　p.4
　1.2.3　Lithography-based processing methods　p.5
　1.2.4　Nanoimprint lithography　p.6
　1.2.5　Other methods　p.8
　1.3　Purpose of this study　p.9
　1.4　Composition of this thesis　p.11
CHAPTER 2　Experimental procedure
　2.1　Preparation of starting materials　p.13
　2.2　Condition of mixing rate　p.15
　2.3　Condition of replicationand drying processes　p.16
　2.4　Condition of sintering program　p.17
　2.5　Characterization tools　p.19
CHAPTER 3　Structure analysis of ceramic patterns after drying
　3.1　Introduction　p.20
　3.1.1　Wettability　p.20
　3.1.2　Aspect ratio　p.23
　3.2　Frabrication on fine-structured size after drying　p.23
　3.3　Loss and collapse of fine-structure patterns after drying　p.26
　3.3.1　Origin of non-forming patterns　p.26
　3.3.2　Effect of submicron-sized patterns related with wettability　p.27
　3.3.3　Effect of residual water and stress between patterns during drying　p.31
　3.4　Conclusions　p.32
CHAPTER 4　Fabrication of fine-structured patterns on ceramic surface body and typical sintering behavior analysis
　4.1　Introduction　p.34
　4.2　Fabrication of oxide ceramic sintered body with fine-structured using Si mold　p.34
　4.2.1　Surface observation of fine-structured patterns　p.34
　4.2.2　Observation and analysis of sintering behavior　p.37
　4.3　Fabrication of oxide ceramic sintered body with fine-structured using quartz mold　p.45
　4.3.1　Problem of Si mod with submicron size　p.45
　4.3.2　Surface observation of fine-structured patterns with submicron size　p.45
　4.4　Conclusions　p.51
CHAPTER 5　Mechanism of pattern and surface deformation by sintering behavior
　5.1　Introduction　p.52
　5.2　Characterization ananlysis of patterns by sintering behavoir　p.52
　5.2.1　Problem of pattern deformation during sintering　p.52
　5.2.2　Distribution of grain size by sintering temperature　p.55
　5.2.3　Grain growth with sintering time　p.59
　5.2.4　Relationship between average grain size and pattern size　p.62
　5.2.5　Effect of abnormal grain growth and evaporation　p.66
　5.3　Characterization ananlysis of patterns deformation　p.69
　5.3.1　Amplitude and FWHM　p.69
　5.3.2　Relationship between amplitude, grain-size and FWHM　p.70
　5.4　Mechanism of pattern deformation　p.72
　5.4.1　Origin of pattern deformation　p.72
　5.4.2　Origin of pattern loss　p.73
　5.5　Conclusions　p.74
CHAPTER 6　Conclusions　p.76
References　p.80
Acknowledgements　p.84
Reseach Performance　p.85

　The ability to fabricate high precision micro- to nanoscale structures in a wide variety of materials is of crucial importance for the advancement of microtechnology, nanotechnology and nanoscience. For example, developing micrometer and sub-micrometer architecture for functional ceramics is expected to promote the industrialization of ceramic nanotechnology.
　Numerous studies have been centered on developing novel methods and processes to fabricate fine-structured ceramic patterns. Although several ceramic patterning methods have been developed during the last decades, techniques that can pattern ceramics are very limited. Most commonly used approaches for patterning ceramic surfaces were the hard-lithography techniques, that in many cases are time-consuming, expensive, and low-resolution techniques. This is due in part to the refractory nature of ceramics and the difficulty in etching such materials. For instance, when ceramic patterns are to be prepared by sputtering, one of top-down methods, it is difficult to avoid etching processes in order to lift off the patterns. This may lead to severe problems such as sidewall redeposition, contamination, and structural damage.
　Furthermore, nanoimprint lithography （NIL） using nanoscale molds, first reported by Chou, is recognized as a promising candidate for nanolithography in the next generation. However, the disadvantage of this technique involves expensive and complex processes. The main reason for the expense of the nanoimprint equipment is that the nanoscale molds need to be hardened by thermal and photonic treatments after imprinting.
　On the other hand, by bottom-up methods, difficulties also exist in precisely controlling the shape, size, and relative position of the nanocomponents. Recently, a sol-gel method was applied for the patterning of TiO2 and ZnO. However, this process required both silicon and polymer molds. Furthermore, the complicated chemical process yielded hazardous wastes. Thus, much simple processes to fabricate patterned ceramics have been awaited.
　In this study, a novel method to fabricate submicron-sized patterns using a simple method combining, the advantages of the use of polyvinyl alcohol （PVA） polymer material and oxide ceramic nanosized particles, without using expensive equipments and complicated chemical processes was proposed. Three oxide ceramic nanosized powders were used. PVA was added as a binder for the formation of oxide ceramic suspensions in aqueous solutions. Al2O3 and TiO2 nanosized powder was chosen because of representative function ceramics as structure material and photocatalyst material. ZnO nanosized powder was a well-known semiconducting ceramic materials with a wide band gap of ~3.37 eV and a large exciton binding energy of ~60 meV at room temperature. PVA polymer materials offer several advantages, including low toxicity, low cost, high Young’s modulus, and solubility in water. Furthermore PVA has already been widely used as a low cost binder in the commercial production of ceramics.
　From results of this study, it was found that fine-structured patterns with as small as 300nm pattern size on ceramic surface body of Al2O3, TiO2 and ZnO using the very simple method was successfully fabricated.
　This versatile technique seems to offers the advantages of simplicity and low production cost, and it is capable of facilitating the design of complex patterns involving many applications ranging from catalysts, super-water-repellent, heatproof materials, and microelectronics.
　This thesis consisted of the following chapters.
　Chapter 1, Prolegomenon, describes necessity of ceramic patterns, patterning technique to fabricate fine-structured ceramic patterns and the purpose of this study.
　Chapter 2, Proposal of nanoimprint method and structure analysis by ceramic pattern forming, shows that a nanoimprint method, succeed and failure of fine-structured patterns with submicron-size on ceramic surface body after drying.
　Chapter 3, Fabrication of fine-structured patterns on ceramic surface body and typical sintering behavior analysis, explains fabrication of fine-structured patterns using Si and quartz molds after sintering. Fabricated samples are analyzed with various kinds of instruments such as TEM, SEM, XRD and violet laser microscopy.
　Chapter 4, Mechanism analysis of pattern and surface deformation by sintering behavior, discusses loss or evaporation mechanism of patterns on ceramic surface body by sintering behavior. A mechanism of pattern deformation was proposed and examined using data of abnormal grain growth.
　In chapter 5, Summary, based on the data and analysis in previous chapters, the summary of this thesis is given.

　本論文「Surface control and Sintering Behavior of the Fine-Structured Ceramics Sintered Body（セラミックスの表面微細構造成型手法および焼結挙動に関する研究）」と題し、以下の6章より構成されている。
　第1章「Introduction （序論）」では、まず、微細セラミックスパターンの必要性と競争技術の問題点について解説した。これらから、今後社会で要求される安価かつ簡便に微細加工を有するセラミックス焼結体創製手法の提案を行い、本論文の詳細な目的を示している。
　第2章「Experimental procedure　（実験方法）」では、 本研究で用いた原料、原料の混合比の選定、実験方法及び焼結の条件とを示している。さらに、作製したパターンの評価手法について説明している。
　第3章「Structure analysis of ceramic patterns after drying　（セラミックス成型におけるナノインプリント方式の提案とその構造解析）」では、PVA、水、セラミックス粉末を有するスラリーとモールドによる成型方法の提案を行っている。乾燥後の微細セラミックスパターンの検証と失敗したパターンの構造分析を行ない、乾燥後のパターンの成立条件を示している。
　第4章「Fabrication of fine-structured patterns on ceramic surface body and typical sintering behavior analysis （セラミックス表面微細構造成型体に特有の焼結挙動解析）」では、焼結後、微細セラミックスパターンの検証を行い、最小300nmのAl2O3、TiO2、ZnOパターンを作製出来ることを、分析結果から説明している。
　第5章「Mechanism of pattern and surface deformation by sintering behavior （セラミックス表面微細構造成型およびその焼結挙動条件、異常粒成長の影響、焼結時間の影響などの関係を見出している。これらから、粒成長のデータを用いて、微細セラミックスパターンの最小加工寸法や最適焼結時間を推定する関係式を提案した。　第6章「Conclusions （結論）」では、 本研究において得られた成果をまとめ、総括としている。
　本論文で示されたこれらの知見は、 安価かつ簡便に微細加工を有するセラミックス焼結体を作製する手法と微細セラミックスパターンの成立条件を含んでおり、本論文は工学上及び工業上貢献するところが大きく、博士（工学）の学位論文として十分な価値を有するものと認める。