Effective measurement of fabricated structures is critical to the cost-effective production of modern electronics. However, traditional tip-based approaches are poorly suited to in-line inspection at current manufacturing speeds. We present the development of a large area inspection method to address throughput constraints due to the narrow field-of-view (FOV) inherent in conventional tip-based measurement. The proposed proof-of-concept system can perform simultaneous, noncontact inspection at multiple hotspots using single-chip atomic force microscopes (sc-AFMs) with nanometer-scale resolution. The tool has a throughput of ∼60 wafers / h for five-site measurement on a 4-in. wafer, corresponding to a nanometrology throughput of ∼66,000 μm2 / h. This methodology can be used to not only locate subwavelength “killer” defects but also to measure topography for in-line process control. Further, a postprocessing workflow is developed to stitch together adjacent scans measured in a serial fashion and expand the FOV of each individual sc-AFM such that total inspection area per cycle can be balanced with throughput to perform larger area inspection for uses such as defect root-cause analysis.
Nanoscale size effects give rise to near-field thermal considerations when heating nanoparticles under high laser power. We solve Maxwell’s equations in the frequency domain to analyze near-field thermal energy effects for three nanoparticle assemblies with different variances in particle sizes and show that heat dissipation generally decreases as the spread in nanoparticle sizes increases within the nanoparticle packing. For this study, log-normally distributed copper nanoparticle packings with a mean radius of 116 nm and three different standard deviations (12, 48, and 84 nm) were created by using a discrete element model in which a specified number of particles is generated. The nanoparticle packings in the simulation are created by randomly placing each nanoparticle into the packing domain with a random initial velocity and a position. The nanoparticles are then allowed to interact with each other under gravitational and weak van der Waals forces until they settle to form a stable packing configuration. A finite-difference frequency-domain analysis, which yields the electromagnetic field distribution, is then applied to the packing by solving Maxwell’s equations to obtain absorption, scattering, and extinction coefficients. This analysis is used to calculate the surface plasmon effects due to the electromagnetic coupling between the nanoparticles and the dielectric medium under the different distributions and show that different particle distributions can create different plasmonic effects in the packing domain, which results in nonlocal heat transport. Overall, this analysis helps to reveal how sintering quality can be enhanced by creating stronger laser–particle interactions for specific groups of nanoparticles.
Nanoscale size effects bring additional near-field thermal considerations when heating nanoparticles under
high laser power. Scanning electron micrographs of a typical copper nanoparticle powder bed reveal that the
nanoparticles are distributed log-normally with 116 nm mean radius and 48 nm standard deviation. In this paper, we
solve Maxwell’s equations in frequency domain to understand near-field thermal energy effects for different standard
deviations. Log-normally distributed copper nanoparticle packings which have 116 nm mean radius with 3 different
standard deviations (12, 48 and 84 nm) are created by using Discrete Element Model (DEM) in which certain number
of particles are generated, specifying a position and radius for each. The solid particles interacting with the
neighbouring particles are to be distributed randomly into the bed domain with an initial velocity and a boundary
condition, which creates the particle packing within a defined time range under gravitational and weak van der Waals
forces. Finite Difference Frequency Domain analysis, which yields the electromagnetic field distribution, is applied
by solving Maxwell's equations to obtain absorption, scattering and extinction coefficients. We show that different
particle distributions create different plasmonic effects in the bed domain which results in non-local heat transport.
We calculate the surface plasmon effect due to the electromagnetic coupling between the nanoparticles and the
dielectric medium under the different distributions. This analysis helps to reveal how sintering quality can be enhanced
by creating stronger laser-particle interactions for specific groups of nanoparticles.