With continuous scaling and increased design and process complexity, there is an increasing need for semiconductor manufacturing process control. This need calls for not only advanced methods and more capable tools, but also additional intra-wafer and across-lot sampling in order to capture process variations and/or changes in process signatures. In this paper we will demonstrate high speed full wafer metrology use cases from the KLA CIRCL™ platform. The CIRCL platform is typically used for very high throughput inline macro defect inspection. Here we demonstrate that this tool can also be used for certain types of metrology applications. In this paper, we will investigate metrology opportunities with full wafer coverage for critical process parameters on two test vehicles: (1) a 32nm pitch regular line-and-space defect vehicle patterned with single exposure EUV and (2) an iN7 BEOL integration test vehicle, also patterned with single exposure EUV.
Optical scatterometry-based metrology is now widely used in wafer fabs for lithography, etch, and CMP
applications. This acceptance of a new metrology method occurred despite the abundance of wellestablished
CD-SEM and AFM methods. It was driven by the desire to make measurements faster and with
a lower cost of ownership. Over the last year, scatterometry has also been introduced in advanced mask
shops for mask measurements. Binary and phase shift masks have been successfully measured at all desired
points during photomask production before the pellicle is mounted. There is a significant benefit to
measuring masks with the pellicle in place. From the wafer fab's perspective, through-pellicle metrology
would verify mask effects on the same features that are characterized on wafer. On-site mask verification
would enable quality control and trouble-shooting without returning the mask to a mask house. Another
potential application is monitoring changes to mask films once the mask has been delivered to the fab (haze,
oxide growth, etc.). Similar opportunities apply to the mask metrologist receiving line returns from a wafer
fab. The ability to make line-return measurements without risking defect introduction is clearly attractive.
This paper will evaluate the feasibility of collecting scatterometry data on pelliclized masks. We explore
the effects of several different pellicle types on scatterometry measurements made with broadband light in
the range of 320-780 nm. The complexity introduced by the pellicles' optical behavior will be studied.
High-k gate dielectric films with equivalent oxide thickness (EOT) of 3 nm or less are becoming the main theme of research and development in ultra-large-scale integrated circuits industry with device dimensions scaled down to less than 130 nm. Among the high-k gate dielectric materials hafnium dioxide (HfO2) is very promising with its high dielectric constant (approximately 30) and stability in contact with Si. The samples were prepared with a DC magnetron-reactive sputtering method and subsequently annealed in the furnace with a temperature range of 500- 850 degree(s)C. The thickness of the HfO2 varied from 3.5- 18nm with a hafnium silicate interface layer of approximately 1 nm. The electrical measurement showed that the breakdown voltage is inversely proportional to the physical thickness, suggesting the breakdown process occur at the HfO2 thin film rather than in the interface layer. To measure the physical thickness of hafnium dioxide and hafnium silicate interface simultaneously, a research grade bench top rotating compensator spectroscopic ellipsometry (RCSE) in the wavelength range of 195-915 nm was used. The dispersion of HfO2 film was characterized with a two-peak critical point (CP) model and the dispersion of the interface layer of hafnium silicate was characterized with a five-peak CP model. An interface layer thickness of 0.7-2 nm was found for all hafnium dioxide films on Si, depending on the process conditions such as annealing temperature and oxygen flow rate. The same wafers measured by RCSE were later studied by transmission electron microscopy (TEM). The thickness of hafnium dioxide and hafnium silicate determined by TEM is in good agreement with the noninvasive RCSE method.
Although interferometry's earliest and most familiar use is with photons, the discovery of matter-wave (deBroglie-wave) interference for electrons demanded the development of quantum mechanics. Since then, matter-wave interferometry has been performed with neutrons, Cooper electron-pairs, and most recently, with whole atoms and diatomic molecules. This talk describes our recent high-flux atom interferometry experiments using the generalized Talbot-vonLau effect. Our interferometer consists of a sequence of three planar vacuum-slit diffraction gratings, microfabricated from silicon nitride membranes. DeBroglie-wave interference fringes are sensed by measuring the transmission of potassium atoms on a hot- wire as a function of grating relative position. Different spatial Fourier components (up to sixth) in the diffraction pattern are resonant in the interferometer at different atomic velocities (i.e., at different wavelengths). When a laser cooled slow atomic beam is incident, various different diffraction patterns are observed as a function of atomic velocity. In an alternative `Heisenberg Microscope' configuration an incident thermal beam produces a velocity average over different fringe Fourier components. AC modulated weak laser light passing through the interferometer interacts selectively with atoms at a specific velocity. The associated fringe pattern is then ac modulated and revealed by its selective destruction.