Sony Semiconductor Solutions Corporation, Atsugi Tec., 4-14-1 Asahi-cho, Atsugi, Kanagawa, 243-0014, Japan.
Sci Rep. 2017 Jun 19;7(1):3832. doi: 10.1038/s41598-017-04200-y.
We report on the IR sensitivity enhancement of back-illuminated CMOS Image Sensor (BI-CIS) with 2-dimensional diffractive inverted pyramid array structure (IPA) on crystalline silicon (c-Si) and deep trench isolation (DTI). FDTD simulations of semi-infinite thick c-Si having 2D IPAs on its surface whose pitches over 400 nm shows more than 30% improvement of light absorption at λ = 850 nm and the maximum enhancement of 43% with the 540 nm pitch at the wavelength is confirmed. A prototype BI-CIS sample with pixel size of 1.2 μm square containing 400 nm pitch IPAs shows 80% sensitivity enhancement at λ = 850 nm compared to the reference sample with flat surface. This is due to diffraction with the IPA and total reflection at the pixel boundary. The NIR images taken by the demo camera equip with a C-mount lens show 75% sensitivity enhancement in the λ = 700-1200 nm wavelength range with negligible spatial resolution degradation. Light trapping CIS pixel technology promises to improve NIR sensitivity and appears to be applicable to many different image sensor applications including security camera, personal authentication, and range finding Time-of-Flight camera with IR illuminations.
我们报告了后照式 CMOS 图像传感器 (BI-CIS) 的 IR 灵敏度增强，该传感器在晶体硅 (c-Si) 和深沟槽隔离 (DTI) 上具有二维衍射倒置金字塔阵列结构 (IPA)。对具有表面上的 2D IPA 的半无限厚 c-Si 的 FDTD 模拟表明，在 λ=850nm 时，超过 400nm 的光吸收提高了 30%以上，而在 540nm 波长时最大增强了 43%。具有 1.2μm 方形像素尺寸和 400nm 间距 IPA 的原型 BI-CIS 样品在 λ=850nm 时与具有平坦表面的参考样品相比，灵敏度提高了 80%。这是由于 IPA 的衍射和像素边界的全反射。配备 C 型镜头的演示相机拍摄的近红外图像显示，在 λ=700-1200nm 波长范围内灵敏度提高了 75%，空间分辨率几乎没有下降。光捕获 CIS 像素技术有望提高近红外灵敏度，并且似乎适用于许多不同的图像传感器应用，包括带有红外照明的安全摄像机、个人认证和测距飞行时间相机。
