This paper studies and compares different materials proposed as sacrificial and etch-stop layers for a 3D above Integrated Circuits (IC) Nano Electro Mechanical Systems (NEMS) integration. The latter constitutes a powerful approach to build highly sensitive sensors dedicated to gas detection or mass spectrometry. However, this strategy makes the mechanical part release process complex. Indeed, this step, performed by hydrofluoric acid (HF) vapor etching, must not damage the electronic part located below the mechanical one. This paper compares the behavior of materials under HF vapor presence and shows that tetraethyl orthosilicate (TEOS) and boron nitride (BN) materials constitute respectively good sacrificial and etch-stop layers for this integration strategy.
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