SiN/SiCxN stack film as Cu capping layer in Cu/ULK interconnect for 28LP

The application of SiN/SiC_xN stack as capping layer of damascene Cu/ULK interconnect was discussed. The stack film of ultra-thin SiN+SiC_xN Cu capping films were fabricated by plasma enhanced chemical vapor deposition (PECVD) method, which consisted of ultra-thin SiN as barrier and SiC_xN as etch stop layer. The resistance and capacitance of Cu/ULK and the capping film SIN/SiC_xN was measured by regular WAT test, and the RC delay was induced. The structure included 3nm UT-SiN and 28nm C-rich SiC_xN and its K_eff is about 5.3. Electric and reliability test indicated satisfactory RC and V_BD for Cu/ULK interconnects by such capping layer.