A method for chemical mechanical polishing of layers of metals of the platinum group

A method for chemical mechanical polishing of layers of metals of the platinum group metals iridium, comprising the steps of: a) a layer of a platinum group metal is provided, b) a polishing liquid is provided, wherein the polishing liquid ba) 1 to 6 wt .-% of abrasive particles of α-alumina having a Mohs hardness of at least 9, bb) 2 to 20 wt .-% of at least one oxidizing agent selected from the group consisting of Ce (IV) salts, salts of chloric acid, salts of Peroxidschwefelsaure and hydrogen peroxide as well as its salts and bc) 97-74 wt .-% water and contains c) the metal layer is chemically mechanically polished with the polishing liquid.