Method of forming hole in glass substrate by using pulsed laser, and method of producing glass substrate provided with hole

Abstract

Disclosed is a method of forming a hole in a glass substrate by using a pulsed laser, the method including (1) preparing the glass substrate including a first surface and a second surface that face each other; (2) forming a concave portion on the first surface by irradiating, with a first condition, the pulsed laser onto the first surface of the glass substrate through a lens; and (3) forming the hole by irradiating the pulsed laser onto the concave portion with a second condition such that energy density of the pulsed laser is less than or equal to a processing threshold value of the glass substrate.

What is claimed is: 
     
         1 . A method of producing a glass substrate with a hole, the method comprising:
 preparing the glass substrate including a first surface and a second surface that face each other;   forming an absorber layer on the first surface of the glass substrate;   forming a concave portion on the first surface by irradiating, with a first condition, a pulsed laser onto the first surface of the glass substrate through a lens, wherein the first condition is such that the energy density of the pulsed laser is selected to be less than or equal to the processing threshold value of the glass substrate, wherein the concave portion on the first surface has a diameter φ and a depth d, wherein the diameter φ is greater than or equal to a diameter S (φ≥S) of a spot on the first surface formed by the pulsed laser, the diameter S being expressed by a formula (i),
   the spot diameter  S =(4×λ× f×M   2 )/(π× r )   (i),
 
   where λ is a wavelength of the pulsed laser, f is a focal length of the lens, M 2  is an M-squared value, and r is a diameter of a beam of the pulsed laser entering the lens, and wherein the depth d is greater than or equal to 0.7 times the diameter φ; and   forming the hole by irradiating the pulsed laser onto the concave portion with a second condition such that energy density of the pulsed laser is less than or equal to a processing threshold value of the glass substrate, wherein the energy density of the pulsed laser in the second condition differs from the energy density of the pulsed laser in the first condition.   
     
     
         2 . The method according to  claim 1 , wherein the energy density of the pulsed laser in the second condition is greater than the energy density of the pulsed laser in the first condition. 
     
     
         3 . The method according to  claim 1 , wherein a pulse train of the pulsed laser in the second condition is modulated. 
     
     
         4 . The method according to  claim 1 , wherein the wavelength λ of the pulsed laser is less than or equal to 1200 nm. 
     
     
         5 . The method according to  claim 1 , wherein the diameter φ is in a range from 3 μm to 30 μm. 
     
     
         6 . The method according to  claim 1 , wherein the depth d is in a range from 2.1 μm to 120 μm. 
     
     
         7 . The method according to  claim 1 , wherein the diameter S of the spot is less than or equal to 15 μm.