Please use this identifier to cite or link to this item: http://hdl.handle.net/11455/48626
標題: Mechanism and Properties Investigation of Novel Grain Boundary Migration, Internal Friction, Elastic-Plastic Deformation, Cyclic and Temperature Dependent Creep of Nanocrystallize Thin Films
新穎奈米晶系薄膜材料之晶界遷移彈塑變能量內耗與週期及溫度潛變機制之研究
作者: 林明澤
關鍵字: 商品化
機械工程類
摘要: The microsystems technology has grown rapidly in recent years. Continued growth ofcomputing power requires still further miniaturization, with a corresponding need tounderstand how mechanical behavior of all the components. As the technologies of deviceprocesses advanced, many new thin film materials structures had been developed. Manynovel mechanical properties of micrometer to nanometer scale thin films yet beendiscovered.Recently, three articles in “Science” report (1) An experimental investigation ofstress-driven grain boundary migration exhibited as grain growth in nanocrystalline aluminumthin films. (2) Observation of giant diffusivity along dislocation cores of thin metal films andfound that dislocations accelerate the diffusion of impurities inside the thin metals films byalmost three orders of magnitude as compared with bulk diffusion. (3) The deformationrecovery is possible for nanocrystalline metal and suggests that the strain recovery was theresults from the combined effect of a small mean grain size and inhomogeneities in themicrostructure. By contrast, the findings turn over the traditional knowledge for the fact thatthe geometric structure of grain boundaries as mechanically static, immovable structures andplastic deformation is permanent deformation without recovery. These findings uncovered anew chapter in solid mechanics and material science application to microsystem technologiesand yet many unknown mechanical behavior remain.In addition, temperature and time dependence in the modulus of the novel scale-relatedthin film are another mechanical properties that are motivated by the need to characterizeand understand the magnitude and origin of this thin film properties for MEMS andMicrosystems applications.In order to gain a better understanding of mechanical function mechanisms in thenanoscale regime, it is desirable to develop a better characterization method that wouldallow us to extend study on the mechanical behavior of films. Here, the principleinvestigator follow previous projects to propose a three year extensive research that has themerit to study the stress driving grain boundary migration, the plastic deformationalrecovery mechanical behavior of thin films, and capable to study (1) time and (2)temperature dependence of mechanical properties of nanocrystalline thin films. Thetechnique including two aspects of measurement methods; the first method utilized “paddle”cantilever beam coated with a thin film with dimensions as few hundred nanometers to lessthan 10 nanometers. Load the sample by driving its static bending or resonance byelectrostatic actuation with an underlying pull-down electrode, capacitance measurementbased on the top can measure its mechanical behavior with respected to load, time andtemperature. The internal friction can be observed from the resonant frequency and driveamplitude in each tested temperature cycle. If the film with thickness in the range of above200 nm, the second method can be used to study its stress or strain driving grain boundarymigration, plastic deformational recovery, internal friction, elastic-plastic deformation,cyclic and temperature dependent creep and stress relaxation behavior using unaxial tensilemethod.Success completion of this project will provide important information of mechanicalproperties of nanocrystalline thin films in terms of deformation mechanisms, dislocationtheories, grain boundary migration, internal friction, elastic-plastic deformation, cyclic andtemperature dependent creep and stress relaxation. This information will be used to accuratepredict stress models and provide a new sight in mechanics of scientific study for themechanical behavior of thin films for modern microelectronics, MEMS andnanotechnologies.
目前半導體積體電路、光電元件、顯示器、奈米科技與微機電系統等高科技產業已迅速的成長;為研究及發展更新更快之元件,學者專家們不斷的增加微小結構之複雜性及高密度性,以使更多的功能可被安置在一微處理器中;然在持續增加其計算能力的要求下,需要更進一步的微形化,也因此隨著微小化的過程而衍生各種新興材料微結構與機械性質的問題;同時隨著各種先進設備與製程技術的提升,很多新穎之薄膜材料被設計與研發,但由於材料結構在微奈米尺度之各項性質和其巨觀塊狀結構有著極大的不同,在控制化學製程及晶粒大小的過程中產生了許多新穎材料特性改變,此現象對製造生產某些特性需求而調配的機能材料提供一個極大的可行性,對高科技產業的發展與提昇是相當重要的一環。最近在2009年、2008年及2007年科學"Science"期刊中,各刊出了一篇發現對於奈米結晶晶粒nanocrystalline組成之金屬薄膜表現出與傳統對基礎材料力學認知上相反之新穎機械行為,分別為(1)晶粒晶界非固定且會產生遷移的機械行為;此行為推翻了傳統上界定晶界為一靜止結構且其作用在塑性變形中差排滑移之阻障行為的認知;文中報告此新穎之行為在應力作用(尤其剪應力)下極為明顯,因此造成晶粒長大而同時降低材料之降伏強度(2) 奈米結晶晶粒之金屬薄膜內合金或是摻雜之擴散會隨著差排與晶界線加速且於晶界擴散之速度可比塊材快三個次方(three orders of magnitude ) (3)塑性變形回復的機械行為;文中建議此新穎塑性變形回復是來自在微結構裡小而平均的奈米晶粒和薄膜非均質現象所影響的結果。然而有關此金屬薄膜材料晶界遷移與非均質影響其機械行為的現象與理論,目前仍存在許多未知,尤其上述發現之行為推翻了基礎材料科學與應用力學上對於材料的認知:(1)金屬材料之晶粒晶界為一靜止結構且其作用在塑性變形中差排滑移之阻障(2)金屬材料受外力產生之塑性變形為永久變形並不可回復;因此更深入的對於奈微米材料結構機械性質之瞭解在科學的研究上有迫切的需要。目前為止,有許多相關的實驗和理論都是依據材料在大尺度規模時巨觀的性質來推演;相較之下,以材料在微奈米尺度的機械行為依據的實驗與研究探討卻往往因其試件製程與量測機制的種種限制而無法有完整而合理的結果。因此設計研究新而適合量測材料在微小尺度的高準度實驗,進而衍生一完整而有價值的次微米到奈米薄膜材料之新穎機械行為的分析有著重要且亟為迫切的需求。本三年期研究計畫接續主持人前幾年之研究,新規劃兩種溫度與週期變化下之薄膜機械性質測試方法(1)在真空中以靜電力驅動試件於共振頻及自由震盪下同步以電容量測其(常溫、高溫)能量內耗(2)微拉伸方法量測次微米、奈米薄膜在均質平面應力懸臂樑結構之彎曲曲率改變量與拉伸試件靜態潛變與自然共振反應(常溫、高溫、高週期性疲勞測試)來探討其所呈現出的新穎機械性質包括奈米晶系薄膜材料之晶界遷移、塑性回復、彈塑性能量內耗、週期及溫度潛變機制之研究。此研究是計畫主持人依據近幾年來設計執行之研究計畫,並參考國內外各種先進之量測技術而提出之最新且直接的實驗,用以量測運用無塵室標準製程產生之薄膜試件奈米級材料機械性質之量測試驗技術,受量測之試件薄膜厚度可由數百奈米厚到十奈米薄之等級。此計畫可準確的量測試件可能之晶界遷移、塑性回復、薄膜非均質行為、彈塑性及黏彈性行為、溫度對應力與應力釋放之影響、薄膜厚度對薄膜機械性質的影響等。成功的完成這項研究計畫,不僅可以建構出真空高溫自然共振分析次微米-奈米尺度金屬薄膜試件之量測設備,其所產生完整的數據亦可用以分析目前最新穎之材料機械性質,提供微系統設計製造時選用材料之參考,也對產品元件之製程設計與可靠度分析提供一極有價值之研究,更可為研發下一代奈米等級元件設計提供一最新式、嚴謹而可靠之機械性質研究方法。
URI: http://hdl.handle.net/11455/48626
其他識別: NSC100-2628-E005-004-MY3
文章連結: http://grbsearch.stpi.narl.org.tw/GRB/result.jsp?id=2334217&plan_no=NSC100-2628-E005-004-MY3&plan_year=100&projkey=PB10007-1825&target=plan&highStr=*&check=0&pnchDesc=%E6%96%B0%E7%A9%8E%E5%A5%88%E7%B1%B3%E6%99%B6%E7%B3%BB%E8%96%84%E8%86%9C%E6%9D%90%E6%96%99%E4%B9%8B%E6%99%B6%E7%95%8C%E9%81%B7%E7%A7%BB%E5%BD%88%E5%A1%91%E8%AE%8A%E8%83%BD%E9%87%8F%E5%85%A7%E8%80%97%E8%88%87%E9%80%B1%E6%9C%9F%E5%8F%8A%E6%BA%AB%E5%BA%A6%E6%BD%9B%E8%AE%8A%E6%A9%9F%E5%88%B6%E4%B9%8B%E7%A0%94%E7%A9%B6
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