Study of Through Glass Via (TGV) Using Bessel Beam, Ultrashort Two-Pulses of Laser and Selective Chemical Etching

Study of Through Glass Via (TGV) Using Bessel Beam, Ultrashort Two-Pulses of Laser and Selective Chemical Etching

Citation

Kim, J.; Kim, S.; Kim, B.; Choi, J.; Ahn, S. Study of Through Glass Via (TGV) Using Bessel Beam, Ultrashort Two-Pulses of Laser and Selective Chemical Etching. Micromachines 2023, 14, 1766. https://doi.org/10.3390/mi14091766

Keywords

  • Through Glass Via (TGV)
  • Selective laser etching (SLE)
  • Bessel beam
  • Ultrashort-pulsed laser
  • Double pulses
  • 213 ps interval
  • Nanograting
  • Borosilicate glass
  • Chemical etching
  • KOH solution

Brief

A study uses a selective laser etching technique with a Bessel beam and double pulses with a 213 ps interval to enhance the Through Glass Via (TGV) generation rate in borosilicate glass. This technique involves locally modifying the glass with an ultrashort-pulsed laser and then chemically etching the modified area. The study found that enhancing the kinetic energy of electrons using double pulses with a 213 ps interval is more effective for TGV generation than thermal enhancement using double pulses with a 10 ns interval. 

Summary

This article investigates a technique for faster production of Through Glass Via (TGV) holes, which are used in the creation of glass interposers for 3D integrated circuits (3D ICs).

The researchers used a method called selective laser etching (SLE) which involves two steps:

  • Local modification of glass using an ultrashort-pulsed laser: This process alters the physical and chemical properties of the modified area, making it more receptive to etching.
  • Selective chemical etching of the modified area: The modified glass is etched with a potassium hydroxide (KOH) solution, creating the TGV holes.

The authors experimented with different laser pulse parameters to enhance the etching speed, focusing on:

  • Pulse duration: Longer pulse durations (up to 1 picosecond) resulted in deeper TGV holes because more photons could travel deeper into the glass.
  • Pulse interval: Two pulses with a 213 picosecond interval yielded the deepest TGV holes compared to single pulses or intervals of 10 nanoseconds or 500 milliseconds. This is because the shorter interval enhances the kinetic energy of electrons, improving the material's response to etching.

The researchers concluded that:

  • Delivering two laser pulses with a 213 picosecond interval is a promising technique for increasing the production speed of TGV holes.
  • Enhancing the kinetic energy of electrons in the glass during laser modification is more effective for faster etching than increasing heat.

This information is based solely on the provided source. 

Origin: https://www.semanticscholar.org/reader/8c871f0facfada6896df22a870af22d3a9bfa884
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