Abstract Calibration of the porosity as well as the electrochemical anodization rate in a 4-layer porous silicon (PSi) waveguide structure, including a guiding, a confinement and two technological barrier layers, is studied and validated. The objective is to process using standard photolithography a 4-layer PSi micro-resonator (MR) that will be butt-coupled with polymer waveguide and used for biosensing applications. The knowledge of the porosity and thus the refractive index of each PSi layer is then crucial to fabricate the hybrid optical component. The presence of the two PSi barrier layers is necessary to prevent the infiltration of polymers or resin during the process but influences the porosity and the anodization rate of both the guiding and the confinement PSi layers. Their porosity is lower than if these layers had been manufactured separately (one layer only) and the anodization rate is on the contrary higher. Taking into consideration the calibration results to obtain the target thicknesses and refractive indices of the guiding and the confinement PSi layers respectively, a MR based on the 4-layer PSi structure is fabricated. The PSi MR experimental transmission spectrum well corresponds to the simulated one which has been calculated from porosity calibration results and from experimental dimensions of the component measured by scanning electron microscope observations. Finally, a promising theoretical surface sensitivity of 0.06 nm/(pg/mm2) for Bovin Serum Albumin detection with a limit of detection of 0.1 pg/mm2 has been calculated for the PSi MR.

中文翻译：

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在 4 层多孔硅结构中进行孔隙率校准，以制造具有明确定义的折射率并专用于生物传感应用的微谐振器

摘要 研究并验证了 4 层多孔硅 (PSi) 波导结构（包括引导层、限制层和两个技术阻挡层）中的孔隙率和电化学阳极氧化速率的校准。目标是使用标准光刻法处理 4 层 PSi 微谐振器 (MR)，该微谐振器将与聚合物波导对接耦合并用于生物传感应用。因此，了解每个 PSi 层的孔隙率和折射率对于制造混合光学组件至关重要。两个 PSi 阻挡层的存在是必要的，以防止在工艺过程中聚合物或树脂的渗透，但会影响引导和限制 PSi 层的孔隙率和阳极氧化速率。它们的孔隙率低于单独制造这些层（仅一层）的情况，而阳极氧化速率则相反。考虑到分别获得引导和限制PSi层的目标厚度和折射率的校准结果，制造了基于4层PSi结构的MR。PSi MR 实验透射光谱与根据孔隙度校准结果和通过扫描电子显微镜观察测量的组件的实验尺寸计算的模拟光谱相符。最后，计算出 PSi MR 的有希望的理论表面灵敏度为 0.06 nm/(pg/mm2)，用于检测牛血清白蛋白，检测限为 0.1 pg/mm2。