Korean laser-processing specialist Laser Apps announced on December 8 that it has successfully formed ultra-fine through-glass vias (TGVs) on semiconductor glass substrates, achieving a diameter of 30 micrometers with exceptionally high circularity. TGVs act as signal pathways within glass substrates, and reducing their size enables higher input/output density, directly enhancing substrate performance.

The company said the TGVs were fabricated in 0.67-millimeter-thick glass, achieving a very high aspect ratio, with via depth far exceeding the hole diameter. TGV formation is widely regarded as one of the most technically challenging steps in glass substrate manufacturing, as it requires creating extremely fine holes using laser processing and etching, then filling them with copper to electrically connect semiconductor chips to the main board.

Laser Apps specializes in laser processing technologies and has developed proprietary methods for glass substrate cutting and TGV formation. Its core "melting" technology creates localized melting points inside the glass and uses plasma-based fusion to process the material, enabling smooth cross-sections without micro-cracks. Initially applied to glass cutting, the technology has recently been extended to TGV fabrication.

The latest achievement is notable for producing very small vias with near-perfect roundness. High circularity makes subsequent copper plating easier and significantly improves substrate performance and reliability. According to CEO Eun-suk Jeon, Laser Apps has now achieved circularity at the 30-micrometer level that was previously only possible with 50-micrometer vias.

The company also reported a major improvement in mechanical strength. Because the inner walls of the TGVs are smooth and free of micro-cracks, destructive testing conducted by etching partner Econy showed that the glass substrates demonstrated up to 40% higher strength than competing TGV glass substrates. This translates into a lower risk of breakage during downstream processes.

Jeon said that glass breakage and so-called "sewage" or tearing phenomena have long been key obstacles to the commercialization of glass substrates, adding that this breakthrough could help remove a major bottleneck to mass production.

Looking ahead, Laser Apps plans to leverage the technology to target the co-packaged optics (CPO) market. CPO is an advanced packaging approach that transmits data using optical signals rather than electrical ones and is drawing increasing interest for AI, data center, and high-performance computing chips. Because optical transmission requires extremely smooth glass surfaces, high-precision glass processing is considered essential.