共濺鍍製備Cu1-xHfx薄膜擴散阻礙特性之研究

銅金屬化製程已廣泛用於深次微米元件，然而銅原子容易擴散至矽基材造成元件失效，所以必須於銅金屬下導入一層擴散阻障層以阻止銅和矽的相互擴散。由於元件日益縮小擴散阻障層厚度也須減薄致使阻障層特性需求日益嚴苛。本實驗擬探討Cu – Hf合金薄膜特性，期望薄膜經熱處理後Hf能適當擴散至表面以達自我阻障之效果，以防止Cu/Si間互相擴散造成元件失效。除此之外，HfN擴散阻障層應用於Cu金屬化製程特性也將在此論文中探討。本實驗是在不同的Ar:N2流量比例下，於Si (100)基板上製備HfNx之擴散阻障層，並以磁控共濺鍍法(Magnetron Co-sputtering)在阻障層上製備Cu1-xHfx (x = 0 and 1.28 at. %)合金薄膜，再以快速退火爐(Rapid Thermal Annealing )在Ar+H2的氣氛下進行300 - 1000oC熱處理，探討Cu1-xHfx合金薄膜在熱處理後的特性，最後以FPP、XRD、SEM、AES、TEM進行薄膜特性分析。實驗結果得知，Cu(Hf)合金薄膜在Ar:N2=18:2下製備之HfN阻障層上有較好的熱穩定性，Cu(Hf)/HfN (20 nm)/Si之熱穩定性可達800oC，且由AES及TEM分析中得知，Cu1-xHfx合金薄膜在熱處理後Hf原子會往薄膜表面及阻障層介面處擴散而達到更好的阻障效果。

關鍵字

擴散阻障層；合金薄膜；共濺鍍法；氮化鉿

並列摘要

As device scaled down to deep sub-micron technology, copper has replaced aluminum in the interconnect material due to its superior electrical conductivity and excellent resistance to electromigration. However, Cu atoms easily diffuse into device region and induce a deep level trap. A diffusion barrier is therefore required for preventing the inter-diffusion between copper and silicon. This study investigated the barrier properties of HfNx and the characteristics of Cu1-xHfx alloy films via Cu1-xHfx/HfNx/Si stacked structure. The finding revealed Cu1-xHfx (x =1.28 at. %) alloy thin film had a better barrier property than that of pure copper thin film. Besides the hafnium atoms easily diffused to the surface and interface of the film at an elevated temperature, thus inducing an additional barrier to prevent the intermixing between Cu and Si. The sandwiched Cu98.72Hf1.28/HfNx (20 nm)/Si structure had a failure temperature of 800oC, which is potentially to be used for Cu metallization.