Product Overview

TGV (Through Glass Via) technology, also known as glass through-hole technology, is a vertical electrical interconnection technique that penetrates glass substrates. It enables vertical electrical connections on glass substrates, achieving high-density interconnections between chips, as well as between chips and substrates. While TSV (Through Silicon Via) technology is used for interposers in silicon-based substrates, TGV serves the same purpose in glass-based substrates.
Glass substrates represent the next generation of chip base materials, with glass as their core component. The key enabling technology for glass substrate packaging is TGV. The glass substrate industry chain encompasses production, raw materials, equipment, technology, packaging, testing, and applications, with upstream segments focusing on production, materials, and equipment.

Advantages

• Superior High-Frequency Electrical Performance
• Ease of Obtaining Large-Scale Ultra-Thin Glass Substrates
• Cost Efficiency
• Simplified Process Flow
• Strong Mechanical Stability
• Broad Application Potential

Technical Principles


(a) Prepare glass wafers
(b) Form TGVs (Through Glass Vias)
(c) Deposit PVD barrier layer and seed layer, perform dual-side electroplating for copper deposition
(d) Annealing and CMP (Chemical Mechanical Polishing) to remove surface copper layer
(e) PVD coating and photolithography
(f) Fabricate RDL (Redistribution Layer)
(g) Strip photoresist and perform Cu/Ti etching
(h) Form passivation layer (dielectric layer)

Detailed steps:

The TGV (Through Glass Via) fabrication process begins with incoming material inspection, followed by via formation through methods including sandblasting, ultrasonic drilling, wet etching, deep reactive ion etching (DRIE), photosensitive etching, laser etching, laser-induced deep etching, and focused discharge drilling, subsequently undergoing via inspection and cleaning.

Through Glass Vias (TGVs) are fabricated using plasma etching technology.


After the hole is formed, it is necessary to inspect the hole, such as through-hole rate, foreign matter, panel defects, etc.

1. Via Integrity – Detect leaks and non-conductive vias. Aperture size specifications: 10/30/50/70/100 µm; outer diameter must exceed inner diameter by ≥60%. Defect criteria: area; circularity (≥95% control); diameter tolerance (±5 µm).

2. Foreign Material in Vias – Check continuity and detect residues (glass debris, carbon fibers, adhesives, dust).

3. Panel Defects – Cracks, etching defects (pits), contaminants, scratches.

Again, electroplating from bottom to top achieves seamless filling of TGV;


Finally, temporary bonding, back grinding, chemical mechanical polishing (CMP) to expose copper, debonding, and forming a through-glass via (TGV) process technology metal-filled transfer board. During the process, semiconductor processes such as cleaning and testing are also required.

(a) LIDE drilling
(b) Electroplating filling
(c) CMP
(d) Front side RDL formation
(e) Polyimide layer
(f) Bumping
(g) Temporary bonding
(h) Backside grinding & RDL formation
(i) Carrier wafer de-bonded



Applications
High-frequency communications (5G/6G chip packaging)
High-performance computing and AI chips
Autonomous LiDAR modules, automotive radar, EV control units.
Implantable devices (e.g., neural probes), high-throughput biochips.

Q&A
Q1:What is TGV glass?
A1:TGV glass: A glass substrate with vertical conductive vias for high-density chip interconnection, suitable for high-frequency and 3D packaging.

Q2:What is the difference between glass substrate and silicon substrate?
A2:

• Materials: Glass is an insulator (low dielectric loss), silicon is a semiconductor.
• High-frequency performance: Glass signal loss is 10-100 times lower than silicon.
• Cost: Glass substrate costs about 1/8 of silicon.
• TGV (Through Glass Via): A metallized vertical channel formed on a glass substrate, without the need for an additional insulating layer, and a simpler process than through silicon via (TSV).

Q3: Why Choose Glass Core Substrates?
A3:

• High-Frequency Superiority:Low Dk/Df minimizes signal distortion in 5G/6G mmWave bands (24-300 GHz).
• Cost Efficiency:Large-area panel processing (e.g., Gen 8.5 glass panels) reduces costs by 70% vs. silicon wafers.
• Thermal & Mechanical Stability:Near-zero warpage even at ultra-thin (<100 µm) thicknesses.CTE tunability reduces thermal stress in multi-material systems.
• Optical Transparency:Enables hybrid electrical/optical integration (e.g., LiDAR, AR displays).
• Scalability:Supports panel-level packaging (PLP) for mass production of advanced 3D ICs.

Related products