The concept of Perpendicular Shape Anisotropy STT-MRAM (PSA-STT-MRAM) has been recently proposed as a solution to enable the downsize scalability of STT-MRAM devices beyond the sub-20 nm technology node. For conventional p-STT-MRAM devices with sub-20 nm diameters,- the perpendicular anisotropy arising from the MgO/CoFeB interface becomes too weak to ensure thermal stability of the storage layer. In addition,- this interfacial anisotropy rapidly decreases with increasing temperature which constitutes a drawback in applications with a large range of operating temperatures. Here,- we show that by using a PSA based storage layer,- the source of anisotropy is much more robust against thermal fluctuations than the interfacial anisotropy,- which allows considerable reduction of the temperature dependence of the coercivity. From a practical point of view,- this is very interesting for applications having to operate on a wide range of temperatures (e.g. automotive -40 °C/+150 °C). © 2020 The Royal Society of Chemistry.