Substrate dividing method

A semiconductor chip manufacturing method, wherein a semiconductor substrate having a plurality of circuit devices formed in matrix on a front face of the semiconductor substrate is divided into the circuit devices to obtain semiconductor chips, the manufacturing method comprising the steps of:

• irradiating a laser light incident face of a substrate, the substrate comprising semiconductor material and having a surface formed with at least one semiconductor device, with laser light while positioning a light-converging point within the substrate, thereby forming a refractive index change region embedded within the substrate along each line of a plurality of cutting lines arranged in a grid with respect to the substrate, the substrate having a front face and a rear face through the substrate, the front face of the substrate being formed with at least one functional device, the forming of each refractive index change region resulting in the forming of a starting point region configured for cutting the substrate, each refractive index change region being located inside the substrate at a predetermined distance from the laser light incident face of the substrate, and the refractive index change region being formed by inducing a permanent structural change in an ionic valence change, crystallization or polarization orientation thereof within the substrate;
• and
• grinding the rear face of the substrate after the forming of the starting point regions, thereby removing at least a portion of the refractive index change regions that were formed in the substrate;
• wherein a fracture generated in a thickness direction of the substrate from each starting point region reaches at least the front face of the substrate, thereby providing at least one semiconductor chip.

A semiconductor chip manufacturing method, wherein a semiconductor substrate having a plurality of circuit devices formed in matrix on a front face of the semiconductor substrate is divided into the circuit devices to obtain semiconductor chips, the manufacturing method comprising the steps of:

• irradiating a laser light incident face of a substrate, the substrate comprising semiconductor material and having a surface formed with at least one semiconductor device, with laser light while positioning a light-converging point within the substrate, thereby forming a modified region embedded within the substrate along each line of a plurality of cutting lines arranged in a grid with respect to the substrate, the substrate having a front face and a rear face through the substrate, the front face of the substrate being formed with at least one functional device, the forming of each modified region resulting in the forming of a starting point region configured for cutting the substrate, and each modified region being located inside the substrate at a predetermined distance from the laser light incident face of the substrate;
• and
• grinding the rear face of the substrate after the forming of the starting point regions without eliminating any of the modified regions from the substrate;
• wherein the substrate is divided when a fracture generated in a thickness direction of the substrate from each starting point region reaches the front face and the rear face of the substrate, thereby providing at least one semiconductor chip.