Microsphere-assisted, nanospot, non-destructive metrology for semiconductor devices

Abstract

As smaller structures are being increasingly adopted in the semiconductor industry, the performance of memory and logic devices is being continuously improved with innovative 3D integration schemes as well as shrinking and stacking strategies. Owing to the increasing complexity of the design architectures, optical metrology techniques including spectroscopic ellipsometry (SE) and reflectometry have been widely used for efficient process development and yield ramp-up due to the capability of 3D structure measurements. However, there has been an increasing demand for a significant reduction in the physical spot diameter used in the SE technique; the spot diameter should be at least 10 times smaller than the cell dimension (~30 × 40 μm2) of typical dynamic random-access memory to be able to measure in-cell critical dimension (CD) variations. To this end, this study demonstrates a novel spectrum measurement system that utilizes the microsphere-assisted super-resolution effect, achieving extremely small spot spectral metrology by reducing the spot diameter to ~210 nm, while maintaining a sufficiently high signal-to-noise ratio. In addition, a geometric model is introduced for the microsphere-based spectral metrology system that can calculate the virtual image plane magnification and depth of focus, providing the optimal distance between the objective lens, microsphere, and sample to achieve the best possible imaging quality. The proof of concept was fully verified through both simulations and experiments for various samples. Thus, owing to its ultra-small spot metrology capability, this technique has great potential for solving the current metrology challenge of monitoring in-cell CD variations in advanced logic and memory devices.

Mapping single-shot angle-resolved spectroscopic micro-ellipsometry with sub-5 microns lateral resolution

“…Ellipsometry is a powerful optical technique for thin film characterization, based on measuring the change in light polarization upon oblique reflection. Its non-destructive nature, high accuracy, simplicity and availability make ellipsometry an essential tool in various fields of industry and research, such as semiconductors [1][2][3], photovoltaics [4,5], materials characterization [6,7], optical coatings [8,9], two-dimensional materials [10,11], flat panel displays [12][13][14], organic films and surfaces [15,16], antifouling coatings [17,18], biological materials [19,20] and many more.…”

Realization of reconfigurable super-resolution imaging by liquid microlens arrays integrated on light disk

“…镜的成像放大倍数与分辨率 [3][4][5][6][7] .研究者虽然对微透镜辅助超分辨检测在理论和应 用上逐步进入了深入研究,提出了超分辨率提升的方法 [8][9][10][11][12][13][14][15][16][17] .但是难以实现对微透 镜的三维空间位置的操控、周期性排列以及大范围纳米结构的超分辨定位观测与 追踪.…”

Super-Resolution Fluorescence Imaging for Semiconductor Nanoscale Metrology and Inspection

“…However, imaging sub-100 nm structures in semiconductors remains challenging. 15 A potential approach to developing such a new metrology tool is the application of recently developed super-resolution fluorescence microscopy techniques, which have been primarily applied in bioimaging. Examples of such techniques include stochastic optical reconstruction microscopy (STORM), 18 (fluorescence) photoactivation localization microscopy, 19 stimulated emission depletion microscopy, 20 and saturated structured-illumination microscopy.…”

“…However, directly visualizing the nanostructures of semiconductors by using these techniques is inadequate because these approaches have been developed to increase the SNR for sensing but not the spatial resolution for imaging. , Microsphere optical nanoscopy methods − have been developed to overcome the diffraction limit by using the photonic nanojet effect induced by a microsphere; such methods are considered promising for simultaneously measuring the critical dimension of semiconductor features and inspecting nanoscale contaminations or defects. However, imaging sub-100 nm structures in semiconductors remains challenging …”

“…Although scatterometry has ability to capture subwavelength periodic structures, it has been limited to measure isolated or nonperiodic structures. , Various sensing methods such as optical pseudo­electrodynamics microscopy, optical interferometric microscopy have been developed to obtain high SNR in the inspection of semiconductors. However, directly visualizing the nanostructures of semiconductors by using these techniques is inadequate because these approaches have been developed to increase the SNR for sensing but not the spatial resolution for imaging. , Microsphere optical nanoscopy methods − have been developed to overcome the diffraction limit by using the photonic nanojet effect induced by a microsphere; such methods are considered promising for simultaneously measuring the critical dimension of semiconductor features and inspecting nanoscale contaminations or defects. However, imaging sub-100 nm structures in semiconductors remains challenging …”