Guosheng Securities Inc. has released a research report indicating that CoWoS has become a critical packaging solution for high-end AI chips, yet it still faces challenges including insufficient production capacity, high costs, and issues with heat generation and warping. Emerging applications like CPO are also expected to broaden the potential application space. The formation of through-glass vias (TGV) and the metallization inside these vias represent two major technical hurdles in glass substrate manufacturing. The report recommends focusing on three main investment themes: 1) precision TGV processing, covering via formation and related glass substrate fabrication; 2) core equipment suppliers, particularly those involved in TGV laser drilling, PVD seed layer deposition, copper electroplating, and CMP processes; and 3) upstream raw glass manufacturers with R&D and production capabilities that could extend into semiconductor glass substrate applications.

In the post-Moore era, transistors have already approached physical limits. CoWoS packaging faces problems such as capacity shortages, elevated costs, heat dissipation challenges, and warping. As AI chip performance continues to climb, with Nvidia's core GPUs advancing from the 4nm H100 to the 3nm VR200, transistor counts, memory bandwidth, and power consumption keep rising. Relying solely on process node shrinking can no longer sustain performance gains, making advanced packaging and chiplet technology essential pathways to break through these barriers. Currently, 2.5D and 3D advanced packaging routes are developing in parallel, with CoWoS emerging as a key solution for high-end AI chips. However, it still grapples with inadequate capacity, mask size limitations, high costs and yield pressures for large silicon interposers, and warping caused by thermal expansion mismatches in ABF substrates.

Glass substrates outperform alternatives in multiple ways, positioning them as a key development direction for advanced packaging. Compared with organic substrates, silicon interposers, and ceramic substrates, glass offers a low and tunable coefficient of thermal expansion, superior dielectric properties, high flatness, and large-size manufacturing capability. It can support fine-line routing of approximately 2/2 microns and core vias around 25 microns, potentially resolving warping, signal loss, and area utilization issues in large-scale packaging. Glass substrates have already found applications in multiple configurations, including CoPoS, Intel's Glass-Core, CPO, and glass bridges. According to PMarketResearch, the global glass substrate market grew from USD 7.12 billion in 2020 to USD 9.03 billion in 2024, with projections reaching USD 16.81 billion by 2032. Meanwhile, emerging applications such as CPO are also expected to unlock additional growth potential.

TGV formation and via metallization stand as the two most significant technical challenges in glass substrate production. The manufacturing process typically includes glass cutting and cleaning, TGV drilling, wet etching, optical inspection, PVD seed layer deposition, copper electroplating, and ABF lamination for build-up layers. Among these steps, TGV formation directly affects subsequent seed layer deposition, metallization, filling, and reliability. The mainstream approach for TGV drilling currently employs laser-induced modification combined with wet chemical etching (LIDE), which requires femtosecond laser processing and wet etching equipment. For via metallization, seed layer deposition and copper electroplating are essential, followed by CMP to achieve surface planarization. On the equipment front, domestic manufacturers such as DR Laser, HuiCheng Vacuum, Shengmei Shanghai, and Huahai Qingke have already established footprints in related equipment segments.

The report offers investment recommendations across three main tracks. First, TGV precision processing, focusing on glass via formation and related substrate manufacturing. Second, core equipment providers, with emphasis on TGV laser drilling, PVD seed layer deposition, copper electroplating, and CMP process tools. Third, upstream raw glass production, highlighting companies capable of developing and manufacturing glass substrates that could expand into the semiconductor glass substrate arena. Companies worth monitoring include BOE Technology, TCL Technology, Shenzhen Tianma, and Woge Optronics; DR Laser, Han's Laser, Huagong Tech, Inno Laser, Delaser, Hymson, Huahai Qingke, HuiCheng Vacuum, Shengmei Shanghai, Dongwei Technology, and NAURA; as well as Tiancheng Technology, Iris Color, and Kaisheng Technology.

The report also flags potential risks, including the possibility of R&D falling short of expectations, uncertainties surrounding technology roadmap choices, potential inaccuracies in third-party data and information, macroeconomic environment fluctuations, trade restrictions, and risks tied to industry competitive dynamics.