Title :
Copper barrier properties of ultrathin PECVD WxN
Author :
Vijayendran, A. ; Danek, M.
Author_Institution :
Novellus Syst. Inc., San Jose, CA, USA
Abstract :
We evaluated plasma enhanced chemical vapor deposited (PECVD) W xN as a potential copper barrier. Ultrathin (100 Å) PECVD WxN films with N/W stoichiometry ranging from 0.2 to 1.0 and resistivities between 200-1000 μΩ-cm were deposited utilizing WF6-N2-H2 chemistry. The thermal stability of the films as a Cu barrier was evaluated by annealing the Si-WxN-Cu stacks at temperatures up to 700°C. Barrier failure was detected by sheet resistance measurements and surface SIMS. The thermal stability was correlated with N/W ratio and fluorine content as determined by RBS and temperature programmed desorption mass spectroscopy, respectively. Tests showed that films with N/W ratios between 0.3 and 0.4 were stable up to 690°C, while incorporated fluorine was seen to have a detrimental effect on barrier stability. Film conformality was optimized using design of experiments techniques. The highest step coverage was obtained at low deposition temperature, low N2 flow and high H2 flow
Keywords :
Rutherford backscattering; chemical interdiffusion; conformal coatings; copper; design of experiments; diffusion barriers; electric resistance; integrated circuit interconnections; integrated circuit metallisation; integrated circuit reliability; mass spectroscopic chemical analysis; plasma CVD; secondary ion mass spectra; stoichiometry; thermal stability; tungsten compounds; 100 angstrom; 200 to 1000 muohmcm; 690 C; 700 C; Cu barrier; Cu-WN-Si; H2 flow; N/W ratio; N/W stoichiometry; N2 flow; RBS; Si-WxN-Cu stacks; WF6-N2-H2; WF6-N2-H2 deposition chemistry; annealing; barrier failure; barrier stability; copper barrier; copper barrier properties; deposition temperature; design of experiments; film conformality optimization; fluorine content; incorporated fluorine effects; plasma enhanced chemical vapor deposited WxN; resistivity; sheet resistance measurements; step coverage; surface SIMS; temperature programmed desorption mass spectroscopy; thermal stability; ultrathin PECVD WxN; Annealing; Chemicals; Conductivity; Copper; Electrical resistance measurement; Plasma chemistry; Plasma properties; Plasma temperature; Surface resistance; Thermal stability;
Conference_Titel :
Interconnect Technology, 1999. IEEE International Conference
Conference_Location :
San Francisco, CA
Print_ISBN :
0-7803-5174-6
DOI :
10.1109/IITC.1999.787097
