LET (Laser & Etching Technology) for TGV Glass Substrate Processing

Problem solved

The difficulty of forming high-quality, crack-free TGV micro-vias in glass substrates for advanced semiconductor packaging, particularly the trade-off between positional accuracy, via profile control, and substrate damage.

Application contexts

• Glass interposers for 2.5D/3D chiplet packaging
• Semiconductor manufacturing equipment insulating parts (gas shower plates)
• Microfluidic devices with glass through-holes
• RF/microwave modules requiring low-loss glass substrates

Technical principle

A picosecond laser beam creates modified regions within the glass volume along the intended via path. The modified glass etches preferentially in a subsequent wet chemical bath, forming a through-hole. The laser modification pattern and etching parameters control the via profile (straight, hourglass, or tapered). The process works on multiple glass types (alkali-free, quartz, borosilicate, soda-lime) without inducing microcracks.

Typical use cases

• TGV via array formation for glass interposer in chiplet-based AI processors
• Fine-pitch vertical interconnect for 2.5D glass-core substrate prototypes
• Glass insulating components with shaped through-holes for semiconductor etch/CVD equipment