The invention provides a method for producing a flexible barrier sheet (200) comprising a barrier layer (103) and metallic elements (104), said method comprising: a) providing a metallic layer (102) applied on a polymeric support layer (101), the metallic layer having a first surface (105) facing the polymeric support layer and a second surface (106) facing away from said polymeric support layer; b) providing metallic elements on the second surface of the metallic layer; c) providing a barrier layer covering said second surface of the metallic layer and said metallic elements, the barrier layer having a first surface facing the metallic layer and a second surface facing away from the metallic layer; d) releasing the polymeric support layer from the metallic layer; and e) removing the metallic layer from the metallic elements and the barrier layer. The flexible barrier sheet may be used in roll-to-roll fabrication of thin film semiconductor devices requiring a high quality barrier substrate sheet, such as OLEDs.