Manufacturing process of element chip using laser grooving and plasma-etching

1. A manufacturing process of an element chip, comprising:

a preparing step for preparing a substrate having first and second sides opposed to each other, the substrate containing a semiconductor layer, a wiring layer and a resin layer formed on the first side, and the substrate including a plurality of dicing regions and element regions defined by the dicing regions;

a laser grooving step for irradiating a laser beam onto the dicing regions to form grooves so as to expose the semiconductor layer along the dicing regions; and

a dicing step for plasma-etching the semiconductor layer along the dicing regions through the second side to divide the substrate into a plurality of the element chips,

the laser grooving step comprising first and second steps,

wherein the first step includes irradiating an ablation laser beam to ablate the resin layer and the wiring layer so as to expose the semiconductor layer along the dicing regions, and

wherein the second step includes irradiating a melting laser beam to melt a surface of the semiconductor layer exposed along the dicing regions after the first step,

wherein a beam intensity Ia of the ablation laser beam and a beam intensity Im of the melting laser beam satisfy Ia >Im.

2. The manufacturing process of the element chip according to claim 1 ,

wherein the beam intensity Im of the melting laser beam is less than a threshold TD of a beam intensity required for ablating the semiconductor layer.

3. The manufacturing process of the element chip according to claim 1 ,

wherein when TA is defined as a threshold of a beam intensity required for ablating the resin layer, TB is defined as a threshold of a beam intensity required for ablating the wiring layer, TC is defined as a threshold of a beam intensity required for melting the semiconductor layer, and TD is defined as a threshold of a beam intensity required for ablating the semiconductor layer, a following relationship is satisfied,

TB >TD >TC >TA, and

wherein a following relationship is satisfied,

TD >Im ≥TC.

4. The manufacturing process of the element chip according to claim 1 , wherein a beam profile of the melting laser beam in a width direction of the dicing region has a Top-hat distribution.

5. The manufacturing process of the element chip according to claim 1 , wherein an irradiation width of the melting laser beam in a width direction of the dicing region is greater than that of the ablation laser beam.

6. The manufacturing process of the element chip according to claim 1 ,

wherein a beam width of the melting laser beam in a width direction of the dicing region is less than a width of the dicing region,

wherein the melting laser beam is irradiated multiple times in the second step along a plurality of irradiation preset-lines, each of which is spaced away by a predetermined distance from adjacent one in the width direction and extends in a longitudinal direction of the dicing region, and

wherein the predetermined distance between the adjacent irradiation preset-lines is less than the beam width.

7. The manufacturing process of the element chip according to claim 6 ,

wherein the melting laser beam is irradiated multiple times in the second step along three or more irradiation preset-lines, and

wherein the last irradiation of the melting laser beam is made along the irradiation preset-line closest to one side portion of the dicing region.