Glass substrate processing method

A glass substrate processing method comprising:

• a first deformed portion formation step in which a first deformed portion is formed in a glass substrate by moving a first laser beam along a first imaginary line having a first radius;
• a second deformed portion formation step in which a second deformed portion is formed in the glass substrate by moving a second laser beam along a second imaginary line having a second radius larger than the first radius;
• and
• a via-hole formation step in which a via-hole having an enlarged inner diameter portion at both ends thereof adjoining upper and lower surfaces of the glass substrate is formed by dipping the glass substrate with the first deformed portion and the second deformed portion formed therein in an etching solution such that the first deformed portion and the second deformed portion are etched,
• wherein a region of the glass substrate in which the first deformed portion is etched away has a first etch selectivity and a region of the glass substrate in which the second deformed portion is etched away has a second etch selectivity lower than the first etch selectivity.