A micromechanical sensor element and a method for the production of a micromechanical sensor element that is suitable, for example in a micromechanical component, for detecting a physical quantity. Provision is made for the sensor element to include a substrate, an access hole and a buried cavity, at least one of the access holes and the cavity being produced in the substrate by a trench etching and/or, in particular, an isotropic etching process. The trench etching process includes different trenching (trench etching) steps which may be divided into a first phase and a second phase. Thus, in the first phase, at least one first trenching step is carried out in which, in a predeterminable first time period, material is etched out of the substrate and a depression is produced. In that trenching step, a typical concavity is produced in the wall of the depression. A passivation process is then carried out in that first phase, in which the concavity produced in the walls of the depression by the first trenching step is covered with a passivation material. The first trenching step and the first passivation process may be carried out repeatedly in alternating succession within the first phase, with the result that a typical corrugation is obtained on the walls of the depression so produced. In the second phase of the trench etching process, the cavity is produced through the at least one access hole produced by the depression, by carrying out a second trenching step of a predetermined second time period that is distinctly longer in comparison with the first time period.