Synthesizing Various Types Nanosize Zirconia Formulated Slurry and Study of Their Effects on Cu- and STI- Chemical Mechanical Polishings
George C. Tu
|關鍵字:||氧化鋯;奈米粉體;改良式溶膠-凝膠法;銅化學機械研磨;淺溝槽隔離;Zirconia;Nano-powder;Modified Sol-Gel Method;Cu CMP;STI|
|摘要:||本篇論文研究各類型奈米氧化鋯漿料之製造及其對銅及淺溝槽隔離化學機械研磨之影響。在銅化學機械研磨方面，使用YxZ1-xO2-x/2砥粒(abrasive)作為研磨漿料(slurry)。使用溶膠-凝膠法合成YxZ1-xO2-x/2 (x=0, 0.03, 0.08 及0.12)粉末。以不同釔含量摻雜於氧化鋯砥粒中，並對晶體結構、粒徑大小、比表面積、研磨速率及表面粗糙度加以探討。熱處理在800℃時，不同釔含量粉體之晶相變化分別為: ZrO2(單斜晶)、 Y0.03Zr0.97O1.985(單斜晶+正方晶)、Y0.08Zr0.92O1.96(正方晶+立方晶) 及 Y0.12Zr0.88O1.94(立方晶)。以BET及TEM對粒徑作分析，發現釔含量增加時其粒徑隨之減小。以YxZ1-xO2-x/2對銅膜進行研磨，當釔含量增加則研磨速率隨之增加。對銅膜研磨得到較高之研磨速率及粗糙度為具有較大比表面積之砥粒(Y0.12Zr0.88O1.94)。
Various types zirconia formulated slurries were investigated for copper chemical mechanical polishing (Cu-CMP) and shallow trench isolation chemical mechanical polishing (STI-CMP) processes. Cu-CMP was investigated with slurries containing YxZr1-xO2-x/2 abrasives. YxZr1-xO2-x/2(x=0、0.03、0.08 and 0.12) powders were synthesized by Sol-gel method. The crystalline structure, particle size, specific surface area, also with the removal rates and surface roughness after polishing with using slurries formulated with each powders of various concentrated yttrium doped zirconia powders were investigated. The crystalline phase transformation calcined at 800℃ was observed for the various yttrium concentrations, ZrO2, Y0.03Zr0.97O1.985, Y0.08Zr0.92O1.96 and Y0.12Zr0.88O1.94 , which were m(monoclinic), m+t(tetragonal), t+c(cubic) and c phases respectively. Particle sizess were measured by BET and TEM analyses, and it was formed that the particle size decreased with increasing yttrium concentration. For polishing copper substrates with YxZr1-xO2-x/2 abrasives formulated slurries, the results showed that the removal rate increased with increasing yttrium concentration. Higher removal rates and longer surface roughness were obtained as polishing with larger specific surface area abrasives. STI-CMP was investigated by polishing with slurries containing modified porous zirconia, colloidal zirconia hydrogel and modified commerial colloidal silica slurry. In the synthesis of modified porous zirconia, crystallization temperature increase with increase of polymer concentration. The primary particles sizes of A10 were B50 are smaller than that of C1. The C1 sample is reckoned to contain more larger pore with bigger pore diameter, which rendering possibly smaller BET specific area with reduced density. Due to the reduced density, slurry with C1 abrasive would give rise to larger CMP removal rate. Zirconia hydrogel was synthesized by modifying sol-gel method. The secondary particle size distribution and, zeta potential of hydrogel zirconia abrasives, and the resulted polishing removal rates and surface roughness were investigated in teams of various concentration, synthesis temperature and solvent media. Zircona hydrogel synthesized in ethanol medium, the ethoxyl groups act to prevent close approach of individual particles, due to its steric effect and absence of H-bonding, therefore, resulting in narrow and uniform particle size distribution. By water treatment of zirconium hydrogel, the removal rate of TEOS oxide film increases, as stock solution concentration and/or temperature increase. In the study of modified commercial colloidal silica slurry, the CMP removal rates depend on the concentration of Zr4+ salts additive. The removal rate increases as Zr4+ concentration increases.
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