磁控溅射法制备用作铜互连阻挡层的钛-铝薄膜

Ti-Al Film Used as Diffusion Barrier for Copper Interconnection Deposited by RF Magnetron Sputtering

采用射频磁控溅射法在Si（100）基片上首先沉积了厚度40nm的非晶钛-铝薄膜，然后在其上又原位生长了厚度100nm的铜薄膜，制备了铜膜／钛-铝膜／硅试样；对试样分别在400～800℃内进行真空退火处理，用原子力显微镜、X射线衍射仪、四探针测试仪对试样的表面形貌、结晶状态及方块电阻进行了分析。结果表明：当退火温度低于750℃时，试样表面平整，表面粗糙度和方块电阻均较小且基本不随退火温度的升高而改变，此时，非晶钛-铝薄膜能够起到阻挡铜向硅中扩散的作用；当退火温度在800℃时，试样的表面粗糙度和方块电阻急剧增大，此时，非晶钛-铝薄膜已经不能起到阻挡层的作用。

An amorphous Ti-Al film, on which Cu film was in situ prepared, was deposited on the Si （100） substrate by radio frequency （RF） magnetron sputtering to fabricate Cu（100 nm）/Ti-Al （40 nm）/Si samples. The samples were annealed in the temperature range from 400℃ to 800℃ in high vacuum and then characterized by atom force microscopy （AFM）, X-ray diffraction （XRD）, and four-point probe methods. The results show that, when the annealing temperature was below 750 ℃, the sample surface was smooth, and the surface root mean square roughness （Rma） and sheet resistance were smaller and did not change with the annealing temperature, and the amorphous Ti-Al film could prevent the interdiffusion between Cu and Si. However, for the sample annealed at 800 ℃, the surace root mean square roughness and sheet resistance increased dramatically, and Ti-Al film could not be used as an effective barrier anymore.