Redistribution Layer (RDL) interposer of High Bandwidth Memory (HBM) design and signal integrity analysis with proposed diagonal meshed ground for artificial intelligence supercomputer

Abstract

Recently, the demand for high-bandwidth memory is increasing to satisfy the computation of hyper-scale artificial intelligence. Accordingly, the number of I/Os and interconnections for $2.5D/3D$ ICs and the number of high-bandwidth memories used in artificial intelligence computers are increasing. Therefore, improving signal integrity performance of high-bandwidth memory while lowering manufacturing cost is emerging as an important task. In this paper, we design an RDL interposer using a diagonal meshed ground to improve such signal integrity performance and reduce the manufacturing cost of the interposer used in high bandwidth memory, and verify the signal integrity performance compared to the existing silicon interposer. The proposed diagonal meshed ground improves signal integrity performance by improving impedance matching compared to the existing orthogonal meshed ground. Also compared previous orthogonal meshed ground, signal integrity performance can be expected to be further improved by improving inductance and capacitance and also by improving crosstalk. Finally, the RDL interposer using the proposed diagonal meshed ground is compared with the existing silicon interposer to verify whether its performance is effective.