Development of Low Cost Glass-Based Deep Trench Capacitor for 3D Packaging

Glass has emerged as an ideal substrate for integrated passive devices due to its excellent insulation, adjustable coefficient of thermal expansion (CTE), availability in panel-level size and outstanding high-frequency electrical properties (ultra-low dielectric loss and optional dielectric constant). This letter proposes a through glass via (TGV) based deep trench capacitor (DTC) embedded in glass substrate, comprising metal-insulator-metal (MIM) layers fabricated using atomic layer deposition (ALD). The proposed glass DTC module whose capacitance is in proportion to the number of DTC cells demonstrates superior performance with a total capacitance of 8.85 nF in 8 DTC cells, achieving a high capacitance density of 68 nF/mm2, and a breakdown voltage (VBD) of 7.83±2.3 V. Meanwhile, the equivalent series inductance (ESL) and the equivalent series resistance (ESR) of the capacitor was as low as 10 pH and 315 $\text{m}\Omega$ , respectively. Compared with the silicon-based DTC, the proposed DTC offers the advantages of lower cost, higher production efficiency, better electric performance, and smaller form factor. These attributes make it a promising candidate for application in RF fields of 2.5D glass interposer and 3D heterogeneous integration.