Deepening of nanograting structures on Si by a two-step laser spatial-selective amorphization strategy combined with chemical etching

•Deepened Si LIPSSs fabricated by a two-step spatial-selective amorphization strategy.•Depth of the Si LIPSSs increased by 3 times with excellent uniformity and a constant period.•Performance of antireflection and polarization sensitivity are enhanced.•This method can be extended to other metal and semiconductor materials.