Signal Integrity Analysis of Silicon/Glass/Organic Interposers for 2.5D/3D Interconnects

Abstract

In this paper, silicon/glass/organic interposers for 2.5D/3D interconnects are investigated for signal integrity analysis. As total system bandwidth increases, memory industry has been developed to satisfy its requirements. Therefore, High Bandwidth Memory (HBM) is introduced to the market. HBM enables TeraByte/s bandwidth with extremely fine pitch, short interconnects using Through Silicon Via (TSV) within the limited area. In HBM based graphics module needs silicon interposer to route between processor and memory due to its capability to process narrow signal width and space. However, silicon interposer has its limits in cost issue. Thus, various interposer substrates are introduced and compared as a substitution for the silicon interposer. Glass interposer has relatively closely-matched Coefficient of Thermal Expansion (CTE). Organic interposer can be fabricated with lower cost than the others. To compare these various substrates, signal integrity analyses must be performed. Especially, HBM has wide number of I/Os for achieving TB/s bandwidth. In this case, metal space should be narrower and it increases the crosstalk effects. Time-domain simulations are performed and analyzed based on the eye-diagrams. Eye-diagram opening voltage and timing jitter are important signal integrity indexes. To obtain the channels' characteristics, all proposed structures are simulated by 3D Full Electromagnetic (EM) simulator, ANSYS HFSS, and circuit simulator, Agilent Advanced Design System, up to 10Gbps.