Optically monitoring and controlling nanoscale topography during semiconductor etching

Abstract

We present epi-diffraction phase microscopy (epi-DPM) as a non-destructive optical method for monitoring semiconductor fabrication processes in real time and with nanometer level sensitivity. The method uses a compact Mach-Zehnder interferometer to recover quantitative amplitude and phase maps of the field reflected by the sample. The low temporal noise of 0.6 nm per pixel at 8.93 frames per second enabled us to collect a three-dimensional movie showing the dynamics of wet etching and thereby accurately quantify non-uniformities in the etch rate both across the sample and over time. By displaying a gray-scale digital image on the sample with a computer projector, we performed photochemical etching to define arrays of microlenses while simultaneously monitoring their etch profiles with epi-DPM.

Reconstruction of sub-wavelength features and nano-positioning of gratings using coherent Fourier scatterometry

“…In order to obtain the intended line shapes and sizes, a reliable inline process control has to take place. This is achieved by printing special targets on the wafer, typically gratings, which are successively measured in order to adjust dose, exposure time, over-lay/alignment and other relevant process parameters of the photo-lithographic machine [2,3]. Currently, the metrology task of this process control is achieved by means of Incoherent Optical Scatterometry (IOS).…”

The operation mechanism of poly(9,9-dioctylfluorenyl-2,7-diyl) dots in high efficiency polymer solar cells

“…Among numerous donor-acceptor groups, poly [N-9 00 -hepta-decanyl-2,7-carbazole-alt-5,5-(4 0 ,7 0 -di-2-thienyl-2 0 1 0 , 3 0 -benzothiadiazole)(PCDTBT): [6,6]-phenyl-C 71 -butyric acid methyl ester (PC 70 BM) blend has been widely employed into the fabrication of cell devices, demonstrating a high power conversion efficiency (PCE) of 10.2%. 4 But it still lags behind the commercial application level and there are many challenges to overcome on the way to competitively efficient devices, including the need for a detailed knowledge of charge transport and spectrum utilization.…”

Doubling the field of view in off-axis low-coherence interferometric imaging

“…Field of view doubling in off-axis interferometry P Girshovitz and NT Shaked 7 doi:10.1038/lsa.2014.32mass production during the creation of lithographed elements, such as during the fabrication of integrated circuits, 34 as a larger number of elements or wider objects could be produced and examined at a given time. For this demonstration, we integrated an additional lithography imaging system into the microscope, so that we can rapidly image the lithographed element during the curing of photoresist adhesive (NOA 81).…”