Manufacturing method of single-crystal silicon substrate
After separation layers are formed inside a single-crystal silicon ingot, a single-crystal silicon substrate is split off from the single-crystal silicon ingot with use of these separation layers as the point of origin. This can improve the productivity of the single-crystal silicon substrate compared with the case of manufacturing the single-crystal silicon substrate from the single-crystal silicon ingot by a wire saw.
1. A manufacturing method of a single-crystal silicon substrate by which the single-crystal silicon substrate is manufactured from a single-crystal silicon ingot manufactured in such a manner that a crystal plane {100} is exposed in each of a front surface and a back surface, the manufacturing method comprising:
a holding step of holding the single-crystal silicon ingot whose side of the back surface is placed on a holding surface of a holding table by the holding table;
a separation layer forming step of irradiating the single-crystal silicon ingot with a laser beam with such a wavelength as to be transmitted through single-crystal silicon from a side of the front surface while moving a focal point of the laser beam and the single-crystal silicon ingot relative to each other along a first direction that is parallel to the holding surface and that is inclined at an acute angle of equal to or smaller than 5° with a crystal orientation <100> of the single-crystal silicon ingot, in a state in which the focal point is positioned inside the single-crystal silicon ingot, to form a separation layer in a linear region along the first direction inside the single-crystal silicon ingot;
an indexing feed step of moving a position inside the single-crystal silicon ingot at which the focal point is formed by irradiation with the laser beam when the separation layer forming step is executed again along a second direction that is parallel to the holding surface and is orthogonal to the first direction; and
a splitting-off step of splitting off the single-crystal silicon substrate from the single-crystal silicon ingot with use of the separation layers as a point of origin after repeatedly executing the separation layer forming step and the indexing feed step to form the separation layers from a region on one end side in the second direction inside the single-crystal silicon ingot to a region on the other end side.
2. The manufacturing method of a single-crystal silicon substrate according to claim 1 , wherein;
the laser beam is split to generate a plurality of focal points that line up along the second direction in the separation layer forming step.
3. The manufacturing method of a single-crystal silicon substrate according to claim 1 , wherein,
in the separation layer forming step, cracks extend along crystal planes that are crystal planes included in crystal planes {N10} (N is a natural number equal to or smaller than 10) and that are parallel to a crystal orientation that forms an acute angle of equal to or smaller than 5° with the first direction in crystal orientations <100> of the single-crystal silicon ingot.
4. The manufacturing method of a single-crystal silicon substrate according to claim 1 , wherein;
the separation layer forming step and the indexing feed step are repeatedly executed again after the separation layer forming step and the indexing feed step are repeatedly executed to form the separation layers from the region on the one end side to the region on the other end side.
5. The manufacturing method of a single-crystal silicon substrate according to claim 1 , wherein:
the separation layer forming step is executed again after the separation layer forming step but before the indexing feed step.
6. The manufacturing method of a single-crystal silicon substrate according to claim 1 , wherein:
the separation layer is formed in such a manner that a width of the separation layer along the second direction becomes a predetermined length in the separation layer forming step, and
the position inside the single-crystal silicon ingot at which the focal point is formed by irradiation with the laser beam is moved in such a manner that a movement distance along the second direction is equal to or longer than the predetermined length in the indexing feed step.
7. The manufacturing method of a single-crystal silicon substrate according to claim 1 , further comprising:
a planarization step of grinding or polishing the front surface of the single-crystal silicon ingot to planarize the front surface before the holding step.
8. A manufacturing method of a single-crystal silicon substrate by which the single-crystal silicon substrate is manufactured from a single-crystal silicon ingot manufactured in such a manner that a crystal plane {100} is exposed in each of a front surface and a back surface, the manufacturing method comprising:
a holding step of holding the single-crystal silicon ingot whose side of the back surface is placed on a holding surface of a holding table by the holding table;
a separation layer forming step of irradiating the single-crystal silicon ingot with a laser beam with such a wavelength as to be transmitted through single-crystal silicon from a side of the front surface while moving a focal point of the laser beam and the single-crystal silicon ingot relative to each other along a first direction that is parallel to the holding surface and that forms an acute angle of equal to or smaller than 5° with a crystal orientation <100> of the single-crystal silicon ingot, in a state in which the focal point is positioned inside the single-crystal silicon ingot, to form a separation layer in a linear region along the first direction inside the single-crystal silicon ingot, wherein in the separation layer forming step, cracks extend along crystal planes that are crystal planes included in crystal planes {N10} (N is a natural number equal to or smaller than 10) and that are parallel to a crystal orientation that forms an acute angle of equal to or smaller than 5° with the first direction in crystal orientations <100> of the single-crystal silicon ingot;
an indexing feed step of moving a position inside the single-crystal silicon ingot at which the focal point is formed by irradiation with the laser beam when the separation layer forming step is executed again along a second direction that is parallel to the holding surface and is orthogonal to the first direction; and
a splitting-off step of splitting off the single-crystal silicon substrate from the single-crystal silicon ingot with use of the separation layers as a point of origin after repeatedly executing the separation layer forming step and the indexing feed step to form the separation layers from a region on one end side in the second direction inside the single-crystal silicon ingot to a region on the other end side.