THROUGH-GLASS VIA HOLE FORMATION METHOD
A through-glass via hole formation method, includes: an internal deformation region formation step in which an internal deformation region is formed inside a glass substrate at a predetermined distance from a surface of the glass substrate; a surface etching step in which the glass substrate is thinned by immersing the glass substrate in an etching solution such that a portion of the surface of the glass substrate, at which the internal deformation region is not formed, is etched and removed at a first etching rate; and a through-glass via hole formation step in which, with the glass substrate immersed in the etching solution, the internal deformation region is etched and removed at a second etching rate higher than the first etching rate such that a through-glass via hole is formed in the glass substrate along the internal deformation region.
1 . A through-glass via hole formation method comprising:
an internal deformation region formation step in which an internal deformation region is formed inside a glass substrate at a predetermined distance from a surface of the glass substrate by irradiating the glass substrate with a laser beam at an intensity not exceeding an ablation threshold of the glass substrate;
a surface etching step in which the glass substrate is thinned by immersing the glass substrate in an etching solution such that a portion of the surface of the glass substrate, at which the internal deformation region is not formed, is etched and removed at a first etching rate; and
a through-glass via hole formation step in which, with the glass substrate immersed in the etching solution, the internal deformation region is etched and removed at a second etching rate higher than the first etching rate such that a through-glass via hole is formed in the glass substrate along the internal deformation region.
2 . The through-glass via hole formation method according to claim 1 , wherein a thickness of the portion of the surface of the glass substrate removed in the surface etching step is smaller than a thickness of a portion with the internal deformation region formed thereon, which is removed in the through-glass via hole formation step.
3 . The through-glass via hole formation method according to claim 1 , wherein, in the internal deformation region formation step, phase transition from an a-phase to a β-phase occurs in a region inside the glass substrate corresponding to the internal deformation region.
4 . The through-glass via hole formation method according to claim 3 , wherein, in the internal deformation region formation step, the internal deformation region is formed by inducing phase transition of a region inside the glass substrate ranging from an upper end of the internal deformation region to a lower end thereof without moving a focus of the laser beam.
5 . The through-glass via hole formation method according to claim 4 , wherein, the laser beam is in the form of a Bessel beam corresponding in length to the internal deformation region.
6 . The through-glass via hole formation method according to claim 3 , wherein, in the internal deformation region formation step, the internal deformation region is formed by inducing phase transition of a region inside the glass substrate corresponding to the internal deformation region while continuously moving a focus of the laser beam from an upper end of the region to a lower end thereof.
7 . The through-glass via hole formation method according to claim 1 , wherein, in the internal deformation region formation step, the internal deformation region is formed in a closed curve shape inside the glass substrate by sequentially moving the laser beam along a virtual circular moving line having a smaller diameter than the through-glass via hole, and, in the through-glass via hole formation step, a region of the glass substrate located inside the internal deformation region and the virtual circular moving line is removed to form the through-glass via hole in the glass substrate.