Tungsten nitride thin films were grown by atomic layer deposition (ALD) using alternating exposures of B2H6, WF6, and NH3 at 300 °C. The film thickness linearly increased with the number of the reaction cycles and determined growth rate was ∼ 0.28 nm/cycle with B2H6, WF6 and NH3 pulse time of 5, 0.25, and 2 s, respectively. The film had a resisitivity of ∼ 350 μΩ-cm with metallic W-N bond and density of ∼15 g/cm3 at 10 nm thickness. X-ray diffractometry analysis showed that the film had nanocrystalline grains with β-W2N and δ-WN phase. Step coverage was approximately 100% even on the 0.14 μm diameter contact hole with 16:1 aspect ratio. ALD-WNx film was evaluated as a barrier layer for W-plug deposition at the contact with an ultrahigh aspect ratio of about 17 for sub-80 nm dynamic random access memory. The results showed that while TiN control group has failed or has a higher contact resistance, ALD-WNx control group showed a low contact resistance. The plan-view scanning electron microscopy images after focused ion beam milling showed that a new contact integration scheme with ALD-WNx showed better plug filling capability due to its excellent step coverage. We also demonstrated that ALD-WN x was successfully integrated at plate contact of polycrystalline Si or TiN and at via contact.
|Number of pages||7|
|Journal||Advanced Metallization Conference (AMC)|
|Publication status||Published - 2006|
|Event||22nd Annual Advanced Metallization Conference, AMC 2005 - Colorado, Springs, CO, United States|
Duration: 2005 Sep 27 → 2005 Sep 29
All Science Journal Classification (ASJC) codes
- Chemical Engineering(all)