Extending area selective deposition of ruthenium onto 3D SiO2-Si multilayer stacks

Abstract

Recent trends in semiconductor process engineering have resulted in significant adoption of new materials and processes to enable new paradigms in device manufacturing. One such emerging process is area selective deposition where a material can be selectively deposited on an area of interest. In this work, we have demonstrated selective deposition of ruthenium (Ru) on amorphous (a-Si) and polycrystallized silicon (p-Si) to silicon dioxide (SiO2) on both 2D blanket films as well as 3D annealed SiO2–Si multilayer stacks. Amorphous Si once crystallized using high temperature annealing exhibits reduced surface hydrogen content (–Si–H), yet we observed Ru growth on p-Si films that were annealed under multiple conditions (800, 900, and 1000 °C). We have used a combination of Fourier transform-infrared spectroscopy and x-ray photoelectron spectroscopy (XPS) to show that both –Si–H and film crystallinity impact the selective growth of Ru. We have also demonstrated selective deposition of ∼10 nm Ru on p-Si layers and ∼0 nm Ru on SiO2 layers of the annealed 3D SiO2–Si multilayer stack. Additionally, by using a combination of XPS and transmission electron microscopy, we have demonstrated that Ru growth is higher on nongrowth surfaces in 2D substrates than on 3D stacks. Finally, we have shown that this process technology can be further advanced using a combination of selective and nonselective conformal atomic layer deposition processes to develop a novel 3D annealed SiO2–Si multilayer stack, thereby demonstrating a 3D device with low –H content p-Si films. This study can help us to realize new integration schemes for innovative 3D device structures.