Add solder mask over copper pad


I have a pad (5 mm circle) of copper in the Top Copper layer. Normally, the solder mask over the copper is automatically removed. However, I want it to be covered with a solder mask. The pad will be used as a capacitive touch sensor and thus people will put their fingers over it. So for this simple prototype I just want it covered with the solder mask and that should be fine. Is that possible?