Method of processing a substrate

1. A method of processing a substrate, having a first surface with a device area and a second surface opposite the first surface, wherein the device area has a plurality of devices formed therein, the method comprising:

applying a pulsed laser beam to the substrate from the side of the second surface, in a plurality of positions along the second surface, so as to form a plurality of hole regions in the substrate, each hole region extending from the second surface towards the first surface, wherein each hole region is composed of a modified region and a space in the modified region open to the second surface; and

grinding the second surface of the substrate, where the plurality of hole regions has been formed, to adjust the substrate thickness.

2. The method according to claim 1 , wherein the pulsed laser beam is applied to the substrate in a condition where a focal point of the pulsed laser beam is located on the second surface or at a distance from the second surface in the direction from the second surface towards the first surface.

3. The method according to claim 1 , wherein the pulsed laser beam is applied to the substrate in a condition where a focal point of the pulsed laser beam is located on the second surface or at a distance from the second surface in the direction opposite to the direction from the second surface towards the first surface.

4. The method according claim 1 , wherein the substrate is a single crystal substrate or a glass substrate or a compound substrate or a polycrystalline substrate.

5. The method according to claim 1 , wherein the modified region is an amorphous region or a region in which cracks are formed.

6. The method according to claim 1 , wherein the hole regions are formed so as to extend along only a part of the thickness, in the direction from the second surface towards the first surface, of the substrate.

7. The method according to claim 1 , wherein the second surface is ground along the entire extension, in the direction from the second surface towards the first surface, of the hole regions.

8. The method according to claim 1 , wherein the hole regions are formed over the entire second surface.

9. The method according to any one of claim 1 , wherein

a plurality of division lines is present on the first surface, the division lines partitioning the plurality of devices, and

the hole regions are formed only in areas of the second surface which are substantially opposite the division lines.

10. The method according to claim 1 , wherein

at least one beam blocking layer is present on the first surface,

the at least one beam blocking layer is arranged below the devices in the direction from the first surface towards the second surface, and the at least one beam blocking layer is opaque to the pulsed laser beam.

11. The method according to claim 10 , wherein the at least one beam blocking layer extends at least over the entire device area.

12. The method according to claim 10 , wherein

a plurality of separate beam blocking layers is present on the first surface, and

each beam blocking layer is arranged below a respective device in the direction from the first surface towards the second surface.

13. The method according to claim 1 , further comprising polishing and/or etching the second surface after grinding the second surface.

14. The method according to claim 1 , wherein the substrate is made of a material which is transparent to the pulsed laser beam.