以1,2,2,4-四甲基-1-氮-2-環戊烷作為先趨物利用電漿輔助化學氣相沉積法製備低介電碳氮化矽薄膜

Abstract

本研究著重於低介電碳氮化矽薄膜之銅擴散阻障層性質探討。本研究利用電漿輔助化學氣相沉積法於13.56 MHz與0.3 W/cm2低電漿功率下使用單一先趨物1,2,2,4-四甲基-1-氮-2-環戊烷沉積低介電碳氮化矽薄膜，吾人係探討不同沉積溫度(25~300 oC)對於薄膜性質之影響。由Si-N-Si與Si-CH2-Si特徵出現可推測交聯反應發生，且Si-N-Si與Si-CH2-Si鍵結相對含量隨著沉積溫度增加而增加，顯示交聯性亦隨之增加。沉積溫度由25oC至300oC，密度由1.79上升至1.92 g/cm3，介電常數亦伴隨著由2.9增加至3.6。另外，低介電碳氮化矽薄膜的漏電流於1 MV/cm偏壓下隨著沉積溫度增加由1.70毕10-7下降至3.50毕10-9 A/cm2，且因為使用單一先趨物與低電漿功率，使得所有低介電碳氮化矽薄膜皆表現出蕭基 (Schottky) 漏電流傳導機制；此外，所有的低介電碳氮化矽薄膜之崩潰電壓皆高於2.5 MV/cm。於其他性質方面，經過400oC /4hrs嚴苛的熱處理後，所有的低介電碳氮化矽薄膜展現出優異的銅擴散阻障能力，銅擴散深度分別介於13到20 nm之間，且銅擴散阻障能力隨著沉積溫度的增加而增加。另外，所有的低介電碳氮化矽薄膜中，最好之彈性模數為16.7 GPa。

This work examines low-k silicon carbonitride (SiCxNy) films properties as Cu diffusion barrier. Low-k silicon carbonitride (SiCxNy) films with dielectric constant of 2.9–3.6 were prepared by RF (13.56 MHz) plasma-enhanced chemical vapor deposition (PECVD) at 25 to 300oC under low power density of 0.3 W/cm2, using a single source precursor, N-methyl-aza-2,2,4-trimethylsilacyclopentane (MTSCP). The cross-linked structure could be formed on the emergence of Si-N-Si and Si-CH2-Si features, and features enhanced with increasing temperature. Density also rose from 1.79 to 1.92 g/cm3. The leakage current density was reduced from 1.70毕10-7 to 3.50毕10-9 A/cm2 at 1 MV/cm, upon increasing the deposition temperature from 25oC to 300oC. The conduction mechanism of the SiCxNy films all exhibited Schottky emission due to few charged defects by using a single precursor and lower plasma power density of 0.3 W/cm2. And all films showed a good breakdown strength >2.5 MV/cm. Moreover, these films displayed outstanding Cu diffusion depth, 13 to 20 nm after 400oC /4hrs annealing and the highest elastic modulus of 16.7 GPa.