本文關鍵詞：光學表面離子束加工的材料去除機理及表面演化機制研究　出處：《中國科學技術大學》2016年博士論文　論文類型：學位論文

  更多相關文章： 離子束加工 擇優(yōu)濺射 表面粗糙度 表面組成 表面演變 中高頻誤差 連續(xù)介質(zhì) 蒙特卡羅方法

【摘要】：193nm深紫外光刻機和下一代的13.5nm極紫外光刻機是我國半導體行業(yè)和超大規(guī)模集成電路戰(zhàn)略的核心裝備,光刻投影物鏡是其中尤為關鍵的部件,鏡面低空間頻段的面形誤差和中、高空間頻段的粗糙度誤差均有著亞納米量級的超高精度的加工要求。離子束加工憑借其原子級別的去除能力、非接觸式的加工方式和溫和的束面相互作用機制,已應用于光刻物鏡鏡面的修形加工中。本文以投影光刻物鏡所需的大口徑(≥1OOmm)超精度光學元件為對象,對離子束加工過程中的材料去除機理,表面形貌和粗糙度、表面元素組成等演變機制和原子行為,以及基本加工工藝等關鍵問題進行了研究,論文主要工作主要有以下四個方面：其一,從載能離子與材料原子的相互作用出發(fā),基于連續(xù)介質(zhì)建立了一個包含離子濺射相關機理(初次濺射、二次濺射、表面反射、幾何遮蔽效應、再沉積等)與表面擴散相關機理(熱激發(fā)的自擴散、離子引發(fā)的有效擴散、離子增強的粘滯流、彈道位移和Ehrlich-Schwoebel效應等)的離子束去除速率模型,并以此研究了諸多原子機理對表面中、高頻粗糙度的粗化特性和平滑特性。其二,基于晶格動力學和蒙特卡羅概率思想,建立了離子束作用過程的隨機數(shù)學模型。從表面原子及其在離子束作用下的諸多原子行為來體現(xiàn)復雜的材料濺射和擴散機理,進而表征表面形貌和表面粗糙度的中、高空間頻段的演變過程。研究發(fā)現(xiàn)表面原子的行為模式和作用程度以及它們各自的粗化和平滑特性,強烈地受表面形貌特征和束流工藝參數(shù)等支配。從垂直入射到大傾斜角的掠射,表面均呈現(xiàn)出先平滑、后粗化的時間演變規(guī)律,并且其表面粗糙度的增長均符合冪律規(guī)律。其三,針對廣泛應用于光學鏡面的多組分材料在離子束加工中的擇優(yōu)濺射現(xiàn)象,建立了離子束作用過程的多元介質(zhì)雙場耦合模型,并與晶格動力學蒙特卡羅模型和熔融石英實驗比較分析,研究了擇優(yōu)濺射對光學元件表面的‘改組’特性以及表面組分的演變：對于石英材料,其表面硅元素含量經(jīng)離子束加工后由濺射前的33%中增長至40%-42%,并通過表面光學性能的檢測,其折射率比濺射前高出約35%,表明擇優(yōu)濺射所引起的材料表面層改組直接影響了表面的光學性能。其四,針對大口徑鏡面的離子束加工,基于CCOS工藝對離子束加工過程進行了連續(xù)介質(zhì)方程建模。根據(jù)通過實驗、晶格動力學模型與連續(xù)介質(zhì)模型三種方法獲得的離子束去除函數(shù),本文對其在濺射時間、離子能量和入射角度等方面的特性進行了研究,結(jié)果表明離子束的去除速率函數(shù)具有良好的時間穩(wěn)定性和小陡度穩(wěn)定性,這為離子束的低頻面形加工提供了基礎。因此,對離子束加工方程展開并做離散矩陣轉(zhuǎn)化后,以逆濾波去卷積算法求解駐留時間,最終獲得了面形精度為1.175 nm RMS、表面粗糙度Rq值為0.56nmRMS的170mm口徑的平面鏡,和面形精度為1.08nmRMS、中心區(qū)域的表面粗糙度為0.4nmRMS、邊緣區(qū)域表面粗糙度為0.6-0.7nmRMS的130mm口徑的凹球面鏡。
[Abstract]:193nm deep ultraviolet lithography and 13.5nm the next generation of extreme ultraviolet lithography machine is the core equipment of China's semiconductor industry and VLSI strategy, lithographic is one of key parts, the surface shape error of low spatial frequency and mirror, high spatial frequency roughness error has a sub the nano scale ultra high precision machining requirements. Ion beam machining has been applied to the modification of lithographic lens surface with its atomic level removal capability, non-contact processing mode and mild beam to surface interaction mechanism. Based on the projection lithography lens required large diameter (more than 1OOmm) of ultra precision optical components as the object, the removal mechanism of the ion beam in the process of material, surface morphology and roughness, surface element composition and evolution mechanism of atomic behavior, key problems and basic processing technology were studied, the main work of this paper mainly the following four aspects: first, starting from energetic interactions between ions and atomic materials, a mechanism based on the ion sputtering continuum (first two sputtering, sputtering, surface reflection, geometric shielding effect, and deposition) related to surface diffusion mechanism (self diffusion, thermal excitation the effective ion diffusion, ion enhanced viscous flow, ballistic displacement and Ehrlich-Schwoebel effect) of the ion beam removal rate model, and to study the mechanism of the surface of many atoms, The coarsening and smoothing characteristics of high frequency roughness. Secondly, based on the idea of lattice dynamics and Monte Carlo probability, a random mathematical model of the action process of ion beam is established. The mechanism of complex sputtering and diffusion is reflected from the surface atoms and their atomic behavior under the action of ion beam, and then the evolution process of the surface and surface roughness in the medium and high frequency bands is characterized. It is found that the behavior mode and action degree of surface atoms and their respective coarsening and smoothing characteristics are strongly controlled by surface morphology and beam processing parameters. From the vertical incidence to the large dip angle, the surface evolvement regularities of first smoothing and post coarsening, and the growth of surface roughness accords with the power law law. Third, which is widely used in optical mirror multi-component materials in ion beam processing of preferential sputtering phenomenon, established the role of ion beam process of multi medium coupling model, and compared with the lattice kinetic Monte Carlo model and experimental analysis of fused quartz, the evolution of "reorganization 'characteristics on the surface of the optical element with preferential sputtering and the surface components for quartz material, the silicon content on the surface by ion beam sputtering before processing by 33% increased to 40%-42%, and through the detection of surface optical properties, the refractive index is higher than that of about 35% before sputtering, surface layer of materials caused by the reorganization of the preferential sputtering directly affects the optical properties the surface of the. Fourthly, based on the ion beam processing of large aperture mirror, the continuous medium equation modeling was carried out on the ion beam processing process based on CCOS process. According to the ion obtained by experiment, lattice dynamics model and continuum model three methods of beam removal function, this paper studied the sputtering time, the ion energy and the incident angle and other aspects of the characteristics, results show that the rate of ion beam removal function has good stability and small slope stability, which provides the basis for the low frequency ion beam surface machining. Therefore, the ion beam processing equation and discrete matrix transformation, the inverse filtering deconvolution algorithm for solving the residence time, finally obtained the surface accuracy of 1.175 nm RMS, the Rq value of surface roughness of 0.56nmRMS 170mm diameter plane mirror, and surface accuracy for surface 1.08nmRMS, the central region of the roughness. 0.4nmRMS, the edge area of the surface roughness is 0.6-0.7nmRMS 130mm diameter of the concave spherical mirror.
【學位授予單位】：中國科學技術大學
【學位級別】：博士
【學位授予年份】：2016
【分類號】：TN305.7

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