Methods for cleaning integrated circuit (IC) wafers after undergoing planarization processes (for example, chemical mechanical polishing processes) and associated cleaning units and/or planarization units are disclosed herein. An exemplary method includes configuring outlet areas of spray nozzles to deliver a cleaning solution to optimal locations of the IC wafer and delivering the cleaning solution via the spray nozzles having the configured outlet areas to the IC wafer. Each of the outlet areas is configured to achieve a particular velocity of the cleaning solution exiting the outlet area, such that the cleaning solution reaches a particular location of the IC wafer depending on the particular velocity. In some implementations, the cleaning solution enters inlet areas of the spray nozzles at the same flow rate and the cleaning solution exits the outlet areas of the spray nozzles at different velocities.