Manufacturing method for glass substrate, method for forming hole in glass substrate, and apparatus for forming hole in glass substrate

A method for forming a hole with a depth of d (μm) or more in a glass substrate, comprising:

• irradiating the glass substrate with a laser beam emitted from a CO2 laser oscillator for an irradiation time t (μsec), to form a hole in the glass substrate,
• wherein the laser beam is delivered to the glass substrate after being condensed at a focusing lens,
• wherein a power density Pd (W/cm2), defined by
• Pd=P0/S,
• where P0 and S are a power and a beam cross-sectional area of the laser beam just prior to entering the focusing lens, respectively, is 600 W/cm2 or less, and
• wherein the irradiation time t (μsec) satisfies
• t≧10×d/(Pd)1/2.

An apparatus for forming a hole with a depth of d (μm) or more in a glass substrate, comprising:

• a CO2 laser oscillator configured to emit a laser beam;
• and
• a focusing lens configured to condense the laser beam into the glass substrate,
• wherein the glass substrate is irradiated with the laser beam for an irradiation time t (μsec), to form a hole in the glass substrate,
• wherein a power density Pd (W/cm2), defined by
• Pd=P0/S,
• where P0 and S are a power and a beam cross-sectional area of the laser beam just prior to entering the focusing lens, respectively, is 600 W/cm2 or less, and
• wherein the irradiation time t (μsec) satisfies
• t≧10×d/(Pd)1/2.