Please use this identifier to cite or link to this item: http://hdl.handle.net/11455/6029
標題: 鈦酸鈷高介電材料在非揮發性記憶體半球面型複晶矽浮動閘極上之應
CoTiO3 High-k Dielectric on HSG Floating Cell for Nonvolatile Memory
作者: 古惟銘
Gu, Wei Ming
關鍵字: CoTiO3;半球面型複晶矽;HSG;High-k Dielectric;高介電材料;鈦酸鈷
出版社: 電機工程學系
摘要: 
利用低壓化學氣相氧化爐管合成的新高介電材料鈦酸鈷,其可被運用在非揮發性記憶體元件、隨機存取記憶體及金氧半場效電晶體閳極氧化層上,本論文首次以低壓化學氣相沈積爐管直接氧化濺鍍的鈦與鈷薄膜來合成鈦酸鈷薄膜並以不同製程方式的多晶矽為下電極同時選用物理氣相沈積的氮化鈦為上電極,而複晶矽下電極總共有三種不用的製程情況,第一種製程是大結晶顆粒高結晶密度半球面型複晶矽,第二種半球面型複晶矽的型式是小結晶顆粒高結晶密度,最後一型式為小結晶顆粒小結晶密度的半球面型複晶矽,而使用半球面型的複晶矽可以增加浮動閘極的表面積而不需要擴大整個堆疊結構的面積,因此我們可以提高耦合係數使得快閃記憶體的操作電壓可以降低,增加的耦合係數也同時減低了在寫入跟抺除時的操作電壓。
此外,我們也探討鈦酸鈷這高介電質的電容結構的漏電流行為來了解其真正的漏電流機制,此外,這具有阻絕層的鈦酸鈷薄膜電容其有效介電質常數可高達約35,且電容在大結晶顆粒高結晶密度半球面型複晶矽下電極時有最大的表面積,其可增加2.2倍的浮動閘極表面積。

A novel high-k cobalt-titanium oxide (CoTiO3) was formed by low pressure chemical vapor deposition (LPCVD). It can be used for the interpoly dielectrics for nonvolatile memory, storage capacitor dielectric for DRAM and gate oxide for MOSFET applications. In this work, for the first time, the cobalt-titanium oxide (CoTiO3) was fabricated by directly oxidizing sputtered Co/Ti film on the differential process conditions poly-Si bottom electrodes with PVD-TiN as the top plate electrode. There are three various process to form poly-Si electrodes. The first type was hemi-spherical grained (HSG) with big grain size and high density (max AEF); The second type was an HSG formation with small grain size and high density. The last type was HSG formation with small grain size and low density (min AEF) was processed. The HSG poly-Si can enlargement floating gate surface area without increasing cell area. Therefore, we achieved low voltage operating flash memory cell with high coupling ratio. The increasing in the coupling ratio can reduce programming and erasing operation voltages.
In addition, the leakage current behavior in this high-k cobalt-titanium oxide (CoTiO3) capacitor structure was studied to determine the leakage current mechanisms. The effective dielectric constant with buffered layer for CoTiO3 dielectric can reach as high as 35. The capacitor on the HSG poly-Si with big grain size and high density has the largest surface area. It can enlargement floating gate surface area 2.2 times.
URI: http://hdl.handle.net/11455/6029
Appears in Collections:電機工程學系所

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