Soft x-ray: novel metrology for 3D profilometry and device pitch overlay

Abstract

Due to their increasingly complex 3D geometries, upcoming gate all around (GAA) devices pose new metrology challenges for which there is not yet any established HVM metrology solution, in particular for various critical timed etch steps [5]. Soft x-ray (SXR) scatterometry using 10-20 nm wavelength light is a promising next-generation metrology technique for 3D profile metrology and overlay (OVL) applications. This wavelength regime offers unique benefits over existing metrology techniques today: (1) Short wavelengths allow for higher resolution measurements than traditional visible wavelengths could offer, enabling measurement of structures at device pitches. (2) Primarily single scattering yields low correlation between parameters and aids physical interpretation of signals. This enables many parameters of interest to be extracted accurately and simultaneously. (3) SXR provides 3D capability, with stack heights up to 400 nm supported and high depth resolution due to the broadband source and sensor. These properties together make SXR suitable for measuring the 3D profiles of advanced devices such as gate all around (GAA) transistors, as well as after develop (ADI) overlay at device pitch. In this paper, we demonstrate SXR for profile metrology of GAA devices. We show sensitivity to average SiGe lateral recess etch depth as well as individual nanosheet critical dimensions, which cannot be reliably accessed by other nondestructive, inline metrology techniques available today. We furthermore demonstrate sensitivity in ADI OVL measurements directly on device-pitch structures in the presence of an underlying patterned nuisance layer.

Toward Complete All-Optical Intensity Modulation of High-Harmonic Generation from Solids

“…High-harmonic generation (HHG) allows for the coherent generation of ultrashort pulses, which has enabled the field of attosecond science for the study of ultrafast phenomena, − nanoscale microscopy via coherent diffraction imaging, , and increasingly applications within the semiconductor industry for wafer metrology …”

“…High-harmonic generation (HHG) allows for the coherent generation of ultrashort pulses, which has enabled the field of attosecond science for the study of ultrafast phenomena, 1−7 nanoscale microscopy via coherent diffraction imaging, 8,9 and increasingly applications within the semiconductor industry for wafer metrology. 10 Originally done with gases, recently there has been an increasing interest in HHG from solids. 4,11−13 Solids are particularly interesting with regard to HHG as the generation process depends strongly on the electron dynamics, which can vary widely between solids.…”

Improving measurement efficiency of complex transistor structures using surface plasmon resonances

“…The transition from research to industry can only be accomplished if the control of the patterning process of these structures makes significant progress in metrology. [8][9][10][11][12][13][14] Mueller matrix spectroscopy ellipsometry (MMSE), a fast, accurate and non-destructive in-line metrology technique, is a potential metrology method for GAA batch manufacturing processes. [15][16][17][18] In addition, machine learning methods are widely used for in-line metrology of complex structures.…”