An micro electro mechanical sensor comprising: a substrate; and a sensor element movably mounted to a first side of said substrate; wherein a second side of said substrate has a pattern formed in relief thereon. The pattern formed in relief on the second side of the substrate provides a reduced surface area for contact with the die bond layer. The reduced surface area reduces the amount of stress that is transmitted from the die bond layer to the substrate (and hence reduces the amount of transmitted stress reaching the MEMS sensor element). Because the substrate relief pattern provides a certain amount of stress decoupling, the die bond layer does not need to decouple the stress to the same extent as in previous designs. Therefore a thinner die bond layer can be used, which in turn allows the whole package to be slightly thinner.