A system for removing photoresist from semiconductor wafers is disclosed. The system utilizes a solid-state laser having wavelengths in the near-visible and visible portions of the electromagnetic spectrum to remove photoresist without requiring hazardous gases or wet solutions. In addition, the system does not damage the substrate being cleaned, nor leave a carbon residue requiring further processing to remove. The system uses photon energy, oxygen, water vapor and ozone to interact with contaminants on a surface, forming a gas reaction zone (GRZ). The GRZ reacts and completely removes the photoresist or other unwanted contamination.