A non-linear analytic stress model for the analysis on the stress interaction between TSVs

Thermo-elastic strain is induced by through silicon vias (TSV) due to the difference of thermal expansion coefficients between the copper (∼18 ppm/◦C) and silicon (∼2.8 ppm/◦C) when the structure is exposed to a thermal budget in the three dimensional integrated circuit (3DIC) process. These thermal expansion stresses are high enough to induce the delamination on the interfaces between the copper, silicon, and isolated dielectric. A compact analytic model for the strain field induced by different layouts of thermal copper filled TSVs with the linear superposition principle is found to result in large errors due to the strong stress interaction between TSVs. In this work, a nonlinear stress analytic model with different TSV layouts is demonstrated by the finite element method and Mohr’s circle analysis. The stress characteristics are also measured by the atomic force microscope-raman technique at a nanometer level resolution. This nonlinear stress model for the strong interactions between TSVs results in an electron mobility change ~2-6% smaller than that resulting from a model that only considers the linear stress superposition principle

Study of the Characteristic of the Stress Induced by Through-Silicon Via and the Stress Constraint/Modulation Structure

本論文以數值模擬的方式來觀察三維積體電路中的矽穿孔通道周圍之熱應力，並佐以壓阻係數來換算此應力造成之矽基板載子遷移率變化率。目的是縮小載子遷移率變化率過大而被定為禁止擺放元件的排除區域。在考慮矽基板材料非等向性的狀況下，證實當矽穿孔通道在規則擺放時其陣列排列方向與元件電流通道夾角控制之重要性，並在觀察矽穿孔通道受到軸向力時對周圍矽基板施力模式的改變，進而提出逐層固定矽穿孔通道的可能應用方案。在討論現有解決矽穿孔通道產生之熱應力問題的方法後，針對不接觸矽穿孔通道本體的封閉式空氣隙技術，我們亦提出朝開放式改進的可能方向。In this work, numerical simulation was used to predict the thermal stress and keep-out zone defined as where carrier mobility changes too much for the devices to turn on. By considering the anisotropic characteristics of the silicon, it is thought that the angle between the rows of through-silicon via array and the direction of the devices’ channel is a very important parameter. By the simulated stress pattern changed by applying tensile stress along the axis of TSV, a model of the confinement of the motion of the TSV’s surface, leading to the reduction of the area of the keep-out zone, was proposed and verified. Last, we proposed a non-enlosed air-gap structure to improve the existing enclosed one.口試委員審定書 I 致謝 II 摘要 III Abstract IV 目錄 V 圖目錄 VII 表目錄 X 第一章 緒論 1 1.1 前言 1 1.2 研究背景與動機 2 1.3 論文架構 6 第二章 文獻回顧與理論基礎 8 2.1 三維積體電路 8 2.2 矽穿孔通道 9 2.3 異質材料經過溫差負荷所產生之熱應力 13 2.4 Lame distribution 14 2.5 基板載子遷移率隨應力的變化 17 2.6 Keep-out zone 19 第三章 矽穿孔通道產生之應力特性 21 3.1 材料參數 21 3.2 邊界條件 22 3.3 模擬與理論解析解的比較 23 3.4 Keep-out zone的計算 25 3.5 矽穿孔通道間交互作用對Keep-out zone的影響 28 3.6 規則性擺放矽穿孔通道與晶圓方向之關係 33 3.7 矽穿孔通道受軸向力與週圍矽基板受垂直應力之關係 38 第四章 非封閉性溝槽對應力分布之影響 45 4.1 非封閉式環狀溝槽 45 4.2 非封閉式溝槽開口位置對Keep-out zone分布之關係 46 4.3 非封閉式溝槽結構之優缺點 48 第五章 結論 54 參考文獻 5

Residual Stress of Curvature Sapphire Substrate with GaN Film Released by the Application of Trench Structures

Serious wafer curvature and residual stress are formed during the growth of an epi-GaN layer on Sapphire substrates due to the different thermal expansion coefficients in these two materials. By using theoretical analysis and a simulation model using the finite element method to describe the realistic shape of wafer curvature on epi-GaN wafers, we examine the influence which different thickness and thermal expansion coefficients in the top epi-GaN layer have on wafer curvature reduction. In addition a new process to reduce wafer curvature and to relax residual stress is proposed. With an additional laser treatment on a sample surface after the growth of the top epi-GaN layer on a Sapphire substrate has taken place, the wafer curvature can be reduced to ~ 37 mm from the original ~ 45 mm in 2 inch wafers with an optimized surface structure design.<br /

Purple Sweet Potato Leaf Extract Induces Apoptosis and Reduces Inflammatory Adipokine Expression in 3T3-L1 Differentiated Adipocytes

Background. Purple sweet potato leaves (PSPL) are widely grown and are considered a healthy vegetable in Taiwan. PSPL contain a high content of flavonoids, and the boiling water-extracted PSPL (PSPLE) is believed to prevent metabolic syndrome. However, its efficacy has not yet been verified. Therefore, we investigated the effect of PSPLE on adipocytes. Methods. The differentiated 3T3-L1 cells used in this study were derived from preadipocytes that were differentiated into adipocytes using an adipogenic agent (insulin, dexamethasone, and 3-isobutyl-1-methylxanthine); approximately 90% of the cells were differentiated using this method. Results. Treating the differentiated 3T3-L1 cells with PSPLE caused a dose-dependent decrease in the number of adipocytes rather than preadipocytes. In addition, treatment with PSPLE resulted in apoptosis of the differentiated 3T3-L1 cells as determined by DAPI analysis and flow cytometry. PSPLE also increased the expression of cleaved caspase-3 and poly ADP-ribose polymerase (PARP). Furthermore, PSPLE induced downregulation of interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α) gene expression in the differentiated 3T3-L1 cells. Conclusions. These results suggest that PSPLE not only induced apoptosis but also downregulated inflammation-associated genes in the differentiated 3T3-L1 cells