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|Electrical Coupling Test Structures for Blind Copper Filled TSVs in a 300mm Wafer|
|Keywords: TSV, Electrical coupling test, 3D IC integration|
|TSV (Through Silicon Via) is the heart of 3D IC stacked structure, which transmits signals through different chips. Therefore, some electrical defects such as open/short, current leakage, signal bandwidth limit, and signal transmission loss may be induced by the TSV. The parasitical characteristics of TSV depend on its dimensions, fill status, material, thickness of insulation layer, aspect ratio, which can be observed by high frequency electrical measurements. However, the conventional measurement can only be done after wafer thinning, which could lead to a higher manufacturing cost if the electrical performances of the TSV don't meet the specification. In order to resolve the issue, a simple test vehicle with TSV coupling is proposed for measuring the TSV electrical characteristics before wafer thinning, i.e., blind TSV. A novel TSV coupling test structure is proposed for immediate electrical performance of TSV process monitor prior to wafer thinning. The structure requires at least two TSVs as a group, and nearby TSVs are placed in specific spacing. The TSV coupling structure consists of not only self but also coupling parasitic parameters such as resistance (R), capacitance (C), and inductance (L) of TSV and substrate. At the same time, an equivalent circuit model is adapted to explore electrical characteristics and estimate TSV manufacture characteristics. The RLC equivalent circuit is verified by S-parameter in high-frequency measurement approach, using two TSVs as transmission and receiving paths of high frequency AC signal. The TSV coupling test structure with the proposed measurement method can further reveal more physical meanings, such as signal transmission characteristics, at early manufacturing stage so as to largely save cost and time of 3DIC production if the electrical performance of the blind TSV does not meet the specification. In addition, a set of test guidelines for measuring the TSV electrical performance has been proposed. In this study, the copper filled TSV is 10μm in diameter, on a 150μm pitch, and in a 12” (300) wafer.|
|Z. H. Lin, Engineer
Hsinchu, Taiwan 310,