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Glass micromachining – The new frontier for semiconductor packaging

by: adminblogPosted on:
Microscopic TGVs in a semiconductor glass substrate

Synopsis

As the semiconductor industry hits the physical limits of traditional silicon and organic substrates, glass has emerged as the high-performance material of choice for the next generation of micro-electronics. This blog explores the critical role of glass micromachining in advanced semiconductor packaging, particularly for High-Performance Computing (HPC) and AI applications. We examine the technical shift toward System-on-Glass technology and the necessity of Ultra-Short-Pulse (USP) lasers to overcome the inherent brittleness of glass. By detailing the fabrication of Through-Glass Vias (TGVs) and high-density interconnects with zero thermal damage, we demonstrate how glass provides superior flatness, lower signal loss, and better thermal stability than conventional materials. Discover how Dynotech’s precision laser solutions are enabling Indian manufacturers to lead the transition toward 2.5D and 3D packaging architectures, ensuring faster, smaller, and more efficient chipsets for the future of 6G and IoT.

Table of Contents

The Substrate Evolution: Why Glass is Replacing Silicon

The relentless pursuit of Moore’s Law has brought the semiconductor industry to a crossroads. Traditional organic substrates are struggling with warpage, while silicon interposers are becoming prohibitively expensive for large-scale applications. The Substrate Evolution: Why Glass is Replacing Silicon  Glass has emerged as the definitive solution, offering a unique combination of mechanical rigidity, high electrical insulation, and the ability to be manufactured in large, cost-effective panels. However, the transition to glass requires a complete rethinking of fabrication, moving away from traditional etching toward high-precision glass micromachining.

What is Through-Glass Via (TGV) Technology?

What is Through-Glass Via (TGV) Technology?  The “heart” of glass-based packaging is the TGV. These microscopic holes (often less than 20µm in diameter) allow for vertical electrical connections through the glass substrate.

USP Lasers: The Secret to "Cold" Machining of Brittle Materials

USP Lasers: The Secret to “Cold” Machining of Brittle Materials  Because glass is exceptionally brittle and transparent, standard lasers often cause cracking or melting. Ultra-Short-Pulse (USP) lasers (femtosecond and picosecond) solve this by delivering energy so fast that the material is vaporized before heat can spread. This “cold” processing allows for the creation of millions of TGVs with zero micro-cracks and perfectly smooth sidewalls.

Strategic Advantages of Glass in Semiconductor Packaging

Strategic Advantages of Glass in Semiconductor Packaging  extend beyond simple cost-savings.

Superior Flatness and Dimensional Stability

Superior Flatness and Dimensional Stability  Unlike organic laminates, glass remains incredibly flat during high-temperature assembly processes, reducing die-shift and improving the yield of multi-chip modules.

Lower Dielectric Loss for High-Frequency 6G Signals

Lower Dielectric Loss for High-Frequency 6G Signals  Glass possesses an order of magnitude lower dielectric loss than silicon. This makes it the ideal platform for the next generation of 6G telecommunications and RF devices, where signal integrity at sub-THz frequencies is the primary goal.

System-on-Glass (SoG): The Future of Heterogeneous Integration

System-on-Glass (SoG): The Future of Heterogeneous Integration  is where the industry is heading. SoG allows for the integration of chips, memory (HBM), and even optical waveguides onto a single glass substrate. This heterogeneous integration enables shorter interconnects, which directly translates to lower latency and higher bandwidth for AI and High-Performance Computing.

Challenges in Glass Processing: Managing Taper and Micro-Cracks

Challenges in Glass Processing: Managing Taper and Micro-Cracks  Despite its benefits, machining glass is a high-wire act. Precision delivery systems must manage the “taper” of the hole and ensure no residual stress is left behind, as even a tiny defect can lead to glass breakage during subsequent manufacturing steps.

Why Dynotech? Precision Engineering for the Silicon-to-Glass Shift

Why Dynotech? Precision Engineering for the Silicon-to-Glass Shift  With 30+ years of experience, Dynotech is at the forefront of the semiconductor packaging revolution in India. We provide the specialized glass micromachining equipment and process know-how needed to handle advanced substrates like Fused Silica and Borosilicate. By choosing our USP laser solutions, you aren’t just buying a machine; you are investing in the foundational technology that will drive the next decade of micro-electronic innovation.

FAQs

Glass is significantly cheaper than silicon and can be processed in larger panel sizes, lowering the cost per unit. Additionally, glass has better dielectric properties (lower signal loss) and its coefficient of thermal expansion (CTE) can be tailored to match other components, reducing warpage in high-performance chips.

A TGV (Through-Glass Via) is a vertical electrical interconnect that passes entirely through a glass substrate. It is critical for 3D packaging because it allows for the shortest possible connection between chips stacked on top of each other, maximizing speed and minimizing power consumption.

Standard lasers produce heat that causes glass to crack or melt. Ultra-Short-Pulse (USP) lasers deliver energy in femtoseconds, vaporizing the glass instantly. This “cold ablation” prevents thermal stress, ensuring the holes are clean and the glass remains structurally sound.

Yes. While previously a niche technology, advancements in high-speed USP lasers and beam delivery (like those provided by Dynotech) now allow for the drilling of thousands of holes per second, making glass-core substrates a viable reality for high-volume AI and HPC chipsets.

The most common types are Borosilicate glass and Fused Silica. These are chosen for their excellent thermal stability, chemical resistance, and high optical transparency, which also makes them suitable for co-packaged optics (integrating lasers and sensors onto the chip).