Development of low-k copper barrier films deposited by PE-CVD using HMDSO, N/sub 2/O and NH/sub 3/

We have developed new barrier films of SiOCH and SiOCNH to prevent copper diffusion by plasma-enhanced chemical vapor deposition (PE-CVD). These films were formed using hexamethyldisiloxane (HMDSO: a siloxane compound), nitrous oxide (N ₂O) and ammonia (NH ₃). The k values of SiOCH film and SiOCNH film are in the range of 3.9 to 4.3 and 4.2 to 5.1, respectively. The leakage currents of these films, except for the film deposited using only HMDSO, are in the range of 10 ^-10 to 10 ^-9 A/cm at 1 MV/cm. At 3 MV/cm, those of SiOCH films are in the range of 10 ^-8 to 10 ^-7 A/cm, and those of SiOCNH films are in the range of 10 ^-9 to 10 ^-8 A/cm, respectively. The leakage currents of the films before and after annealing at 450°C for 4 hours in nitrogen (N ₂) were compared. There are almost no changes except for the film deposited using only HMDSO. From these results, we can conclude that the k values and the leakage currents of both SiOCH film and SiOCNH film are lower than those of plasma silicon nitride (SiN) film which is conventionally used in 0.18 μm devices as a copper diffusion barrier. In addition, these films have excellent copper barrier property.