Manufacturing method for glass substrate, method for forming hole in glass substrate, and apparatus for forming hole in glass substrate
A manufacturing method for a glass substrate having a hole with a depth of d (μm) or more includes irradiating the glass substrate with a laser beam emitted from a CO 2 laser oscillator for an irradiation time t (μsec), to form a hole in the glass substrate. The laser beam is delivered to the glass substrate after being condensed at a focusing lens. A power density P d (W/cm 2 ), defined by P d =P 0 /S where P 0 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/cm 2 or less. The irradiation time t (μsec) satisfies t ≥10× d /( P d ) 1/2 .
1. A manufacturing method for a glass substrate having a hole with a depth of d (μm) or more, comprising:
placing the glass substrate at a focal point of a laser beam emitted from a CO 2 laser oscillator;
irradiating the glass substrate with the laser beam for at least a minimum irradiation time t (μsec), to apply heat on a portion of the glass substrate at the focal point, thereby removing a substance of the glass substrate at the focal point such that a hole is formed in the glass substrate at the focal point;
wherein
the laser beam is delivered to the focal point on the glass substrate after being condensed at an aspherical focusing lens,
a power density P d (W/cm 2 ) of the laser beam prior to entering the aspherical focusing lens is 600 W/cm 2 or less,
wherein the power density P d is defined by
P d =P 0 /S,
where P 0 (W) and S (cm 2 ) are a power and a beam cross-sectional area of the laser beam respectively, and
the numerical value of the minimum irradiation time t (μsec) is determined by the mathematical value of 10×d/(P d ) 1/2 .
2. The manufacturing method according to claim 1 ,
wherein the CO 2 laser oscillator is a continuous wave CO 2 laser oscillator.
3. The manufacturing method according to claim 1 ,
wherein the CO 2 laser oscillator is a pulsed CO 2 laser oscillator.
4. The manufacturing method according to claim 1 ,
wherein a wavelength of the laser beam emitted from the CO 2 laser oscillator is in a range from 9.2 μm to 9.8 μm.
5. The manufacturing method according to claim 1 ,
wherein the hole is a through-hole.
6. A method for forming a hole with a depth of d (μm) or more in a glass substrate, comprising:
placing the glass substrate at a focal point of a laser beam emitted from a CO 2 laser oscillator;
irradiating the glass substrate with the laser beam for at least a minimum irradiation time t (μsec), to apply heat on a portion of the glass substrate at the focal point, thereby removing a substance of the glass substrate at the focal point such that a hole is formed in the glass substrate at the focal point;
wherein
the laser beam is delivered to the focal point on the glass substrate after being condensed at an aspherical focusing lens,
a power density P d (W/cm 2 ) of the laser beam prior to entering the aspherical focusing lens is 600 W/cm 2 or less,
wherein the power density P d is defined by
P d =P 0 /S,
where P 0 (W) and S (cm 2 ) are a power and a beam cross-sectional area of the laser beam respectively, and
the numerical value of the minimum irradiation time t (μsec) is determined by the mathematical value of 10×d/(P d ) 1/2 .
7. An apparatus for forming a hole with a depth of d (μm) or more in a glass substrate according to the method of claim 1 , comprising:
a support for positioning the glass substrate;
a CO 2 laser oscillator configured to emit a laser beam;
an aspherical focusing lens configured to condense the laser beam into a focal point on the glass substrate,
wherein
the laser beam is delivered to the focal point on the glass substrate after being condensed at the aspherical focusing lens,
a power density P d (W/cm 2 ) of the laser beam prior to entering the aspherical focusing lens is 600 W/cm 2 or less,
wherein the power density P d is defined by
P d =P 0 /S,
where P 0 (W) and S (cm 2 ) are a power and a beam cross-sectional area of the laser beam.
8. The apparatus according to claim 7 ,
wherein the CO 2 laser oscillator is a continuous wave CO 2 laser oscillator.
9. The apparatus according to claim 7 ,
wherein the CO 2 laser oscillator is a pulsed CO 2 laser oscillator.
10. The apparatus according to claim 7 ,
wherein a wavelength of the laser beam emitted from the CO 2 laser oscillator is in a range from 9.2 μm to 9.8 μm.
11. The apparatus according to claim 7 , further comprising an aperture configured to control the beam cross-sectional area of the laser beam between the CO 2 laser oscillator and the focusing lens.
12. The apparatus according to claim 11 , further comprising a λ/4 wave plate between the CO 2 laser oscillator and the aperture.
13. The manufacturing method according to claim 1 ,
wherein a beam average power of the laser beam is 50 W or more.
14. The manufacturing method according to claim 1 ,
wherein the irradiation time t is 380 μsec or less.
15. The method according to claim 6 ,
wherein a beam average power of the laser beam is 50 W or more.
16. The method according to claim 6 ,
wherein the irradiation time t is 380 μsec or less.
17. The apparatus according to claim 7 ,
wherein a beam average power of the laser beam is 50 W or more.
18. The apparatus according to claim 7 ,
wherein the irradiation time t is 380 μsec or less.
19. The manufacturing method according to claim 1 ,
wherein the laser beam emitted from a CO 2 laser oscillator is circularly polarized.