Superconducting High-Aspect Ratio Through-Silicon Vias with DC-Sputtered Al for Quantum 3D integration

Abstract

This paper presents the fabrication and electrical characterization of superconducting high-aspect ratio through-silicon vias DC-sputtered with aluminum. Fully conformal and void-free coating of 300 μm-deep and 50 μm-wide vias with Al, a CMOS-compatible and widely available superconductor, was made possible by tailoring a funneled sidewall profile for the axisymmetric vias. Single-via electric resistance as low as 80.44 m at room temperature and superconductivity below 1.28 K were measured by a cross-bridge Kelvin resistor structure. This work thus demonstrates the fabrication of functional superconducting interposer layers, suitable for high-density 3D integration of silicon-based quantum computing architectures.

Materials in superconducting quantum circuits

“…芯片上的 空气桥使用电子束或者等离子增强化学气相沉积的二 氧化硅作为牺牲层, 可以与倒装焊工艺兼容 [105] . 在芯 片层叠过程中, 高深宽比的硅通孔内需要沉积超导材 料, 可以通过原子层沉积或磁控溅射等方法 [106] , 实现 [108] . 约瑟夫森临界电流可通过室温 下的电阻算出, 易于进行快速器件检测 [109] , 也可激光 退火改变结区的电阻, 按需改变临界电流 [110] .…”

High Coherence in a Tileable 3D Integrated Superconducting Circuit Architecture

“…Various approaches to this have been demonstrated, for example with spring-loaded pogo pins [12,13] and with galvanic bonding of the qubit substrate to a wiring/interposer substrate [14][15][16]. To avoid spurious modes due to slotlines, divided ground planes can be inductively shunted with airbridges [10] or with superconducting through substrate vias (TSVs) [15,17,18]. To avoid low frequency cavity modes, one solution is * peter.leek@physics.ox.ac.uk to divide the quantum processor into subsystems, with each subsystem enclosed in a cavity with dimensions 1 cm [19][20][21][22].…”

Highly-Conformal Sputtered Through-Silicon Vias With Sharp Superconducting Transition

“…Several works in literature have described a variety of approaches to deploy superconducting interposers [6]- [14], including our previous investigations [15], [16]. Foxen et al [7] used indium bumps as electrical interconnects between two planar devices with aluminum wiring.…”

“…We have previously demonstrated the fabrication of high aspect-ratio (HAR) superconducting TSVs using sputtered aluminum [15], [16]. Sputter deposition is a physical vapor deposition technique used for the deposition of thin films.…”