The the polymer film on array (PFA) as planarization layer is important in FFS(Fringe‐Field Switching) and COA(Color filter on Array)display mode,according to its liquid crystal alignment is horizontal. The planarization serves not only as a smooth surface for device build‐up,but also it can reduce parasitic capacitance between metal layers. In this paper,we found that the planarization layer is easily deamged by subsequent processes because it is organic. It found that when the silicon oxide (SIOx)as passivation layer slowly deposited on the common ITO upon planarization layer , the planarization layer would be damaged seriously.And the demage degree is related to siloxane content in PFA and subsequent layer incluse the common ITO electrode thickness and and passivation layer's process parameters and materials between common electrode and pixel electrode.