Dicing method for semiconductor substrate

1. A method for dicing a semiconductor substrate comprising:

forming a reforming layer in the substrate by irradiating a laser beam on a first side of the substrate;

forming a groove on a second side of the substrate along with a dicing line; and

applying a force to the substrate in order to dice the substrate at the reforming layer as a starting point of dicing, wherein

the groove has a predetermined depth so that the groove is disposed near the reforming layer

the force provides a stress at the groove,

a distance between the groove and the reforming layer is equal to or smaller than 30 μm, and

the groove is separated from the reforming layer,

wherein the second side is different from the first side.

2. The method according to claim 1 , wherein

the substrate is a semiconductor wafer, and

the substrate is diced into a plurality of chips.

3. The method according to claim 1 , wherein

the groove is disposed on a first side of the substrate, and

the force is applied to the first side of the substrate toward an outer periphery of the substrate in a radial direction of the substrate.

4. The method according to claim 1 , wherein

the groove is disposed on a first side of the substrate, and

the force is applied to a second side of the substrate toward an outer periphery of the substrate in a radial direction of the substrate.

5. The method according to claim 1 , wherein

the forming the groove is performed before the forming a reforming layer.

6. The method according to claim 1 , wherein

the forming the groove is performed after the forming a reforming layer.

7. A method for dicing an object comprising:

irradiating a laser beam on the object in order to form a plurality of reforming layers in the object along with a dicing line by multi-photon absorption effect, wherein the reforming layers are formed in a multi-layered structure manner in a thickness direction of the object; and

applying a force on a first side of the object in order to dice the object from the reforming layers as a starting point of dicing, wherein

the reforming layers are disposed in a first reforming region and a second reforming region,

the first reforming region is disposed in the first side of the object, and the second reforming region is disposed in a second side of the object,

the reforming layers in the first reforming region have a first distance between two neighboring reforming layers, and the reforming layers in the second reforming region have a second distance (Sa) between two neighboring reforming layers, and

the first distance of the first reforming region is smaller than the second distance of the second reforming region so that the reforming layers are concentratedly arranged in a range of the first side of the object.

8. The method according to claim 7 , wherein

the first distance of the first reforming region becomes narrower as it approaches a surface of the first side of the object.

9. The method according to claim 7 , wherein

the first reforming region includes a surface side first reforming region and an inner side first reforming region,

the surface side first reforming region is disposed on a surface side of the first side of the object, and the inner side first reforming region is disposed on an inner side of the first side of the object,

the reforming layers in the surface side first reforming region have a surface side first distance between two neighboring reforming layers, and the reforming layers in the inner side first reforming region have an inner side first distance between two neighboring reforming layers, and

the surface side first distance of the surface side first reforming region is smaller than the inner side first distance of the inner side first reforming region.

10. A method for dicing an object comprising:

irradiating a laser beam on the object in order to form a plurality of reforming layers in the object along with a dicing line by multi-photon absorption effect, wherein the reforming layers are formed in a multi-layered structure manner in a thickness direction of the object; and

applying a force on a first side of the object in order to dice the object from the reforming layers as a starting point of dicing, wherein

the reforming layers are disposed in a first reforming region and a second reforming region,

the first reforming region is disposed in the first side of the object, and the second reforming region is disposed in a second side of the object,

the first reforming region includes a first number of the reforming layers, and the second reforming region includes a second number of the reforming layers, and

the first number is larger than the second number so that the reforming layers are concentratedly arranged in a range of the first side of the object.

11. The method according to claim 10 , wherein

the reforming layers in the first reforming region becomes dense as it approaches a surface of the first side of the object.

12. The method according to claim 10 , wherein

the first reforming region includes a surface side first reforming region and an inner side first reforming region,

the surface side first reforming region is disposed on a surface side of the first side of the object, and the inner side first reforming region is disposed on an inner side of the first side of the object,

the surface side first reforming region has a surface side density of the reforming layers, and the inner side first reforming region has an inner side density of the reforming layers, and

the surface side density is larger than the inner side density.

13. A method for dicing an object comprising:

irradiating a laser beam on the object in order to form a plurality of reforming layers in the object along with a dicing line by multi-photon absorption effect, wherein the reforming layers are formed in a multi-layered structure manner in a thickness direction of the object; and

applying a force on a first side of the object in order to dice the object from the reforming layers as a starting point of dicing, wherein

the reforming layers are disposed in a surface side reforming region and an inner side reforming region,

the surface side reforming region is disposed in a surface side of the object, and the inner side reforming region is disposed in an inner side of the object,

the reforming layers in the surface side reforming region have a surface side distance between two neighboring reforming layers, and the reforming layers in the inner side reforming region have an inner side distance between two neighboring reforming layers, and

the surface side distance of the surface side reforming region is smaller than the inner side distance of the inner side reforming region so that the reforming layers are concentratedly arranged in the surface side reforming region of the object.

14. The method according to claim 13 , wherein

the surface side reforming region includes a first surface side reforming region and a second surface side reforming region,

the first surface side reforming region is disposed on the first side of the object, and the second surface side reforming region is disposed on a second side of the object,

the reforming layers in the first surface side reforming region have a first surface side distance between two neighboring reforming layers, and the reforming layers in the second surface side reforming region have a second surface side distance between two neighboring reforming layers, and

the first surface side distance is equal to or smaller than the second surface side distance.

15. A method for dicing an object comprising:

irradiating a laser beam on the object in order to form a plurality of reforming layers in the object along with a dicing line by multi-photon absorption effect, wherein the reforming layers are formed in a multi-layered structure manner in a thickness direction of the object; and

applying a force on a first side of the object in order to dice the object from the reforming layers as a starting point of dicing, wherein

the reforming layers are disposed in a surface side reforming region and an inner side reforming region,

the surface side reforming region is disposed in a surface side the object, and the inner side reforming region is disposed in an inner side of the object,

the surface side reforming region has a surface side density of the reforming layers, and the inner side reforming region has an inner side density of the reforming layers, and

the surface side density is larger than the inner side density so that the reforming layers are concentratedly arranged in the surface side reforming region of the object.

16. The method according to claim 15 , wherein

the surface side reforming region includes a first surface side reforming region and a second surface side reforming region,

the first surface side reforming region is disposed on the first side of the object, and the second surface side reforming region is disposed on a second side of the object,

the first surface side reforming region has a first surface side density of the reforming layers, and the second surface side reforming region has a second surface side density of the reforming layers, and

the first surface side density is larger than the second surface side density.

17. A method for dicing a semiconductor substrate comprising:

irradiating a laser beam on the semiconductor substrate along with a dicing line in order to form a reforming area in the substrate by multi-photon absorption effect, wherein the reforming area is formed at a focus point of the laser beam in the substrate;

bonding a first side of the substrate on a sheet;

expanding the sheet with the substrate in order to dicing the substrate from the reforming area as a starting point of dicing; and

controlling a strength of the laser beam in accordance with dimensions of the reforming area at the focus point and a depth of the focus point from a surface of the substrate, wherein

the laser beam is controlled in such a manner that the dimensions of the reforming area disposed near the first side of the substrate are larger than the dimensions of the reforming area disposed near a second side of the substrate so that the reforming layer having the large dimensions is formed near the first side of the substrate,

the reforming area is formed at a plurality of positions in a thickness direction of the substrate,

the laser beam has a laser power defined as LP in watt unit,

the depth of the focus point is defined as D in micrometer unit, and

the laser beam is controlled based on a formula of LP=0.001×D+0.355.

18. The method according to claim 17 , wherein

the laser beam is controlled in such a manner that the dimensions of the reforming area disposed near the first side of the substrate becomes larger as it goes to a surface of the first side of the substrate, and

the reforming area is formed at a plurality of positions in a thickness direction of the substrate.

19. The method according to claim 17 , wherein

the reforming area is formed at a plurality of positions in a thickness direction of the substrate, and

the laser beam is controlled in such a manner that the dimensions of the reforming area at each position are substantially the same.

20. The method according to claim 17 , wherein

the reforming area is formed at a plurality of positions in a thickness direction of the substrate, and

the reforming area at one position does not overlap the reforming area at another position.

21. The method according to claim 17 , wherein

the reforming area is formed at a plurality of positions in a thickness direction of the substrate, and

the reforming area disposed near the first side of the substrate is formed faster than the reforming area disposed near a second side of the substrate.