X-ray fluorescence (XRF) is a well-established method for quantitative elemental analysis. For accurate quantification, secondary excitation has to be taken into account. In this paper, the secondary excitation process was discussed for analysis by confocal micro-XRF. Experimental depth profiles were shown for a layered sample of Co and Cu. An additional peak was observed in the depth profile of Co, and it was explained by secondary excitation process. Additionally, a Mosaic model was proposed for quantification of confocal micro- XRF analysis.