- 學位論文
離子佈植對銻薄膜相變化行為之影響
Influence of Ion Implantation on Phase-Change Behaviors of Sb Films
摘要
本論文研究利用離子佈植的方式來探討相變化記憶體材料的改質行為，首先討論相變化材料Ge2Sb2Te5經由氮與氧離子分別佈植後，其相變行為將如何改變，接者探討銻超薄膜覆蓋各種不同的保護層後，其相變行為是否比Ge2Sb2Te5優秀，最後探討矽離子佈植於覆蓋各種不同保護層的銻超薄膜相變特性有何影響。 第一部分的研究為氮與氧離子分別佈植於Ge2Sb2Te5薄膜以改善其相變特性，佈植劑量為8×1015與3.2×1016 ions/cm2。低劑量氮離子佈植時，結晶溫度從158 ℃增加至170 ℃，結晶活化能從2.73 eV增加至3.33 eV，十年數據存留度從81 ℃增加至100 ℃，而高劑量氮離子佈植時，結晶溫度、結晶活化能、數據存留度分別為176 ℃、3.12 eV、102 ℃，氮離子佈植於Ge2Sb2Te5的改質效果比佈植氧離子好。 第二部分的研究為覆蓋各種不同保護層與不同銻膜厚(5 nm~15 nm)的超薄膜相變行為，並且研究矽離子佈植對其有何影響。覆蓋Si3N4的5 nm銻超薄膜其結晶溫度為191 ℃，結晶活化能為4.70 eV，數據存留度為135 ℃，比Ge2Sb2Te5的數據存留度高54 ℃。利用Zacharias公式將膜厚推測到接近1.7 nm時，其結晶溫度將會剛好等於熔點溫度，覆蓋Si3N4抑制銻超薄膜結晶的效果比覆蓋SiC與Al2O3的銻超薄膜佳，覆蓋Al2O3的銻超薄膜會因為與鋁和氧接觸而產生二元和三元氧化物，所以會導致其熱穩定性不佳。經過矽離子佈植後，只有覆蓋Si3N4的7nm銻超薄膜其熱穩定性增加，其餘的都會因離子佈植而破壞保護層抑制結晶化的效果，導致銻超薄膜熱穩定性降低，甚至在離子佈植後就變為結晶態。
並列摘要
This study investigates the ion-implantation doping behavior of phase change memory materials. First, we discuss the phase-change characteristics of the Ge2Sb2Te5 films subjected to N+ or O+-implantation. Secondly, we study the phase-change characteristics of the ultra thin Sb films enclosed by different capping layers and then compare with those of Ge2Sb2Te5 films. Finally, we study the phase-change characteristics Si+-implanted ultra thin Sb films enclose by different capping layers. The first part studies the improvement of phase-change characteristics of Ge2Sb2Te5 films by N+ or O+ implantation, respectively. The implantation doses are 8×1015 and 3.2×1016 ions/cm2. When implantation dose is 8×1015 ions/cm2, the crystallization temperature(Tx) increases from 158 to 170 ℃, the activation energy of crystallization(Ea) increases from 2.73 to 3.33 eV, and the temperature of 10-year data retention(T10y) also increases from 81 to 100 ℃, respectively. When implantation dose is 3.2×1016 ions/cm2, the Tx, the Ea, and the T10y are 176 ℃, 3.12 eV, 102 ℃, respectively. The doping effect of N+-implanted films is better than that of O+-implanted films. The second part of study is to investigate the phase-change behaviors of the ultra thin Sb films subjected to Si+ implantation. The Tx of the 5 nm thick Sb film capped with Si3N4 is 191 ℃, the Ea is 4.70 eV, and the T10y is 135 ℃. The T10y of the 5 nm thick Sb film is 54 ℃ higher than Ge2Sb2Te5 film. By using Zacharias’s equation, the Tx of 1.7 nm thick Sb film is equal to its melting temperature. The suppression of crystallization by Si3N4 capping layer is better than those by SiC and Al2O3 capping layers. The thermal stability of the Al2O3 capping layer degraded due to the formation of oxidative compound in Sb film. Si3N4 is the only capping layer that may increase the thermal stability of Sb film subjected to Si+ implantation. Since it may resist the degradation caused by the ion-implantation.