Methods for forming via hole and filling via hole in flexible substrate

A method for filling a via hole in a flexible substrate, comprising:

• forming the first via hole in the flexible substrate through:
• providing a base substrate and forming a de-bonding layer on the base substrate;
• forming a seed metal layer on the de-bonding layer, and patterning the seed metal layer to form a first conductive pattern;
• forming a first flexible substrate on the seed metal layer;
• forming a first mask layer on the first flexible substrate;
• and
• forming a first via hole in the flexible substrate through a dry etching process, the first via hole penetrating through the first flexible substrate to expose a connection region of the first conductive pattern;
• filling the first via hole with a conductive metal through an electroplating process;
• and
• removing the de-bonding layer through laser to remove the first flexible substrate from the base substrate;
• wherein the first via hole comprises a first actual via hole and a first dummy via hole, wherein the filling the first via hole with the conductive metal through the electroplating process comprises:
• forming a first etch stopping barrier in the first dummy via hole;
• filling the first actual via hole with the conductive metal through the electroplating process;
• removing the first etch stopping barrier in the first dummy via hole to expose a first to-be-etched region of the seed metal layer;
• removing the first to-be-etched region through a wet etching process;
• and
• filling the first dummy via hole with the photoresist through a photolithography process to form a first planarization layer.