雙亞基鉬錯合物及鋁烷化合物經化學氣相沉積法成長薄膜

Abstract

本實驗成功地以1當量的Mo(NtBu)2Cl2DME和1當量LiNEt2合成出 Mo( NtBu)2(NEt2)2以並用1當量LiAlH4，1當量Me2EtN.HCl和1當量Me2EtN合成 出AlH3(NMe2Et)n (n=1 or 2)並以 Mo(NtBu)2(NEt2)2和AlH3(Me2EtN)n (n=1 or 2)為單源前驅物利用冷璧式反應器經有機金屬化學氣相沉積法成 長薄膜以Mo(NtBu)2(NEt2)2為前驅物成長薄膜時,前驅物氣化溫度為 318K ，沉積溫度為723-923K下可於Si基材上成長出緻密的多晶薄膜.由WDS分析 中發現薄膜之組成為MoCxNyOz,x=0.06-0.63, y=0.49-0.76,z=0.02-0.34 而薄膜中碳,氮含量在通載流氣體時皆隨沉積溫度上昇而下降，未通載流 氣體則大致維持不變．由XRD數據得知，薄膜具有立方晶形之結構，其晶 格常數介於4.17-4.22A之間．反應過程中所產生之低沸點副產物經GC-MS ，RGA鑑定為H2，CH4，EtN=CMeH，Et2NH，CH3CN和 (CH3)2C=CH2．從這些 副產物的分析推測可能的反應途徑 tBuN和Et2N基可能以β-hydrogen elimination和γ-methyl ination途徑活化分解以AlH3(NMe2Et)n(n=1 or2)為前驅物成長薄膜時，前驅物氣化溫度為263K，沉積溫度為363-503K 發現沉積過程具有非常良好的選擇性，Al薄膜只沉積在Si，TiN和TiSi2基 材上而不會沉積在SiO2基材上．由SEM研究中發現很好的均一覆蓋性( conformalcoverage)．AES研究中發現成長出的薄膜為品質良好之鋁膜.電 阻值3.1μohm-cm比塊材(2.7μhom-cm)高10-20%．以Mo(NtBu)2(NEt2)2為 前驅物製出之薄膜經AES研究發現，其具有擴散障礙層的潛力. The imido complex Mo(NtBu)2(NEt2)2 and alaneound AlH3(NMe2Et)n (n=1 or2) were successfully synthesized. Mo(NtBu)2(NEt2)2 was prepared by the reaction of Mo(NtBu)2Cl2DME with LiNEt2. AlH3( NMe2Et)n (n=1 or2) wasthesized by reacting LiAlH4 with 1eq. of Me2EtN.HCl andMo(NtBu)2(NEt2)2 and AlH3(NMe2Et)n (n=1 or2) were used as precusor to depo-sit thin films on silicon substrates in a cold-wall CVD reactor at 0.03-0.1 Torr,723-923K and 363-503K,respectively. The thin films were characterized by SEM, XRD,WDS and ESCA. For this films deposited from Mo(NtBu)2( NEt2)2, SEM and XRD indicated that the films were poly- crystalline. WDS studies show that the conctitution of the films were MoCxNyOz, x=0.06-0.63, y=0.49-0.76, z=0.02-0.34, with increasing deposition temperature, the carbon and nitrogen centration decreased. XRD studies found that when the temperature deposition has increased, the films show sharp and shift diffraction peaks. Compare with the WDS data, with increasing N/Mo, C/Mo ratio,the lattice parameter increased. Volatile products were analyzed by RGA. From the analysis, decomposition of the tBuN and Et2N groups by β-hydrogen elimination and methyl elimination pathways are proposed. For Al thin films deposited from AlH3(NMe2Et)n (n=1 or2), SEM indicated that they were grown selectively on Si, TiN and TiSi2 in the presence of SiO2. The average grain size for Al on Si is approximately 500A, ten times smaller than found on TiN(5000 A), indicating that Al nuclei are much easily formed on TiN than SiO2. Conformal deposition can be easily achieved for filling unity aspect ratio holes. XRD studies found very sharp diffraction peaks. The resistivity for Al films are 3.1 uohm- cm, which is 10-20% higher than the 2.7 uohm-cm bulk resistivity. We also explore the films deposited from Mo( NtBu)2(NEt2)2 which covered Al thin films deposited from AlH3( NMe2Et)n (n=1or2) as diffusion barrier.