Magnetically-coupled current probing structure consisting of TSVs and RDLs in 2.5D and 3D ICs

Simultaneous switching current (SSC) drawn by integrated circuits (ICs) creates simultaneous switching noise (SSN) on power nets, which causes a number of SI/PI problems, such as reduced noise margin and eye opening with increased SSN. Analyzing the effects of SSC and SSN is especially important for ICs targeted for mobile applications whose operating frequency keeps on increasing with decreasing operating voltage. Therefore, it is of utmost importance to measure SSCs for a thorough analysis of high-speed systems. In this paper, a magnetically-coupled current probing structure consisting of TSVs and RDLs, namely TSV-based Current Probe (TCP), is proposed for measuring the SSC resulting from the logical activity of the I/O buffers in 2.5D and 3D-ICs. SSCs are found by capturing the magnetic flux induced by the SSC of interest with the proposed current probing structure, and then reconstructing the original current waveform using the transfer impedance profile. Through a series of simulation in frequency and time domains, we verified the performance of the proposed probing structure consisting of TSVs and RDLs and proved it can effectively measure the SSC. Lastly, a test vehicle is fabricated on package level for experimental verification of the proposed probing structure.