Gully-Santiago Michael, Jaffe Daniel T, White Victor
Appl Opt. 2015 Dec 1;54(34):10177-88. doi: 10.1364/AO.54.010177.
Silicon direct bonding offers flexibility in the design and development of Si optics by allowing manufacturers to combine subcomponents with a potentially lossless and mechanically stable interface. The bonding process presents challenges in meeting the requirements for optical performance because air gaps at the Si interface cause large Fresnel reflections. Even small (35 nm) gaps reduce transmission through a direct bonded Si compound optic by 4% at λ=1.25 μm at normal incidence. We describe a bond inspection method that makes use of precision slit spectroscopy to detect and measure gaps as small as 14 nm. Our method compares low-finesse Fabry-Perot models to high-precision measurements of transmission as a function of wavelength. We demonstrate the validity of the approach by measuring bond gaps of known depths produced by microlithography.
硅直接键合通过允许制造商将子组件与潜在无损且机械稳定的界面相结合，为硅光学器件的设计和开发提供了灵活性。键合过程在满足光学性能要求方面存在挑战，因为硅界面处的气隙会导致较大的菲涅耳反射。即使是小的（35纳米）气隙，在垂直入射时，λ = 1.25μm 处也会使直接键合的硅复合光学器件的传输降低4%。我们描述了一种键合检测方法，该方法利用精密狭缝光谱学来检测和测量小至14纳米的气隙。我们的方法将低精细度法布里 - 珀罗模型与作为波长函数的高精度传输测量进行比较。我们通过测量由微光刻产生的已知深度的键合间隙来证明该方法的有效性。
