Advanced nanoanalysis of a Hf-based high-<i>k</i> dielectric stack prior to activation

Analytical electron microscopy techniques are used to investigate elemental distributions across a high-&lt;i&gt;k&lt;/i&gt; dielectric stack with a metal gate. Electron energy-loss spectroscopy results from a Si(100)/SiO2/HfO2/TiN/a-Si gate stack confirm the presence of an oxide interfacial phase at the TiN/a-Si interface prior to activation of the stack

A nanoanalytical investigation of elemental distributions in high-<i>k</i> dielectric gate stacks on silicon

Two high-&lt;i&gt;k&lt;/i&gt; gate stacks with the structure Si/SiO&lt;sub&gt;2&lt;/sub&gt;/HfO&lt;sub&gt;2&lt;/sub&gt;/TiN/poly-Si are characterised using previous termnanoanalyticalnext term electron microscopy. The effect of two key changes to the processing steps during the fabrication of the stacks is investigated. Electron energy-loss spectroscopy is used to show that the TiN layer has a very similar composition whether it is deposited by PVD or ALD. Spectrum imaging in the electron microscope was used to profile the distribution of elements across the layers in the stack. It was found that when the anneal after HfO&lt;sub&gt;2&lt;/sub&gt; deposition is carried out in a NH3 atmosphere instead of an O2 atmosphere, there is diffusion of N into the SiO&lt;sub&gt;2&lt;/sub&gt; and HfO&lt;sub&gt;2&lt;/sub&gt; layers. There is also significant intermixing of the layers at the interfaces for both wafers

Nucleation, crystallisation and phase segregation in HfO2 and HfSiO

Hafnia and hafnium silicate thin films and bulk powders were analysed using thermal analysis, X-ray diffraction and transmission electron microscope techniques to improve understanding of the crystallisation mechanism of the dielectric material. It was found that thin films exhibit instability under device processing conditions. Starting precursors greatly affect the crystallisation pathway in the bulk materials. By studying these phenomena a better understanding of the chemistry involved during crystallisation can be gained