Shrinking design rules and reduced process tolerances require tight control of critical dimension (CD) linewidth, feature shape, and profile of the printed geometry. The holistic metrology approach consists of utilizing all available information from different sources such as data from other toolsets, multiple optical channels, multiple targets, etc., to optimize metrology recipe and improve measurement performance. Various in-line CD metrology toolsets such as scatterometry optical CD, CD-SEM, and CD-AFM are typically utilized individually in fabs. Each of these toolsets has its own set of limitations that are intrinsic to specific measurement technique and algorithm. Here we define "hybrid metrology" to be the use of any two or more metrology toolsets in combination to measure the same dataset. We demonstrate the benefits of the hybrid metrology on two test structures: 22-nm-node gate develop inspect and 32-nm-node fin-shaped field effect transistor gate final inspect. We will cover measurement results obtained using typical BKM (nonhybrid, single toolset standard results) as well as those obtained by utilizing the hybrid metrology approach. Measurement performance will be compared using standard metrology metrics; for example, accuracy and precision.
Improvement in metrology performance when using a combination of multiple optical channels vs. standard single
optical channel is studied. Two standard applications (gate etch 4x and STI etch 2x) are investigated theoretically
and experimentally. The results show that while individual channels might have increased performance for few
individual parameters each - it is the combination of channels that provides the best overall performance for all
Shrinking design rules and reduced process tolerances require tight control of CD linewidth, feature shape, and profile of
the printed geometry. The Holistic Metrology approach consists of utilizing all available information from different
sources like data from other toolsets, multiple optical channels, multiple targets, etc. to optimize metrology recipe and
improve measurement performance. Various in-line critical dimension (CD) metrology toolsets like Scatterometry OCD
(Optical CD), CD-SEM (CD Scanning Electron Microscope) and CD-AFM (CD Atomic Force Microscope) are typically
utilized individually in fabs. Each of these toolsets has its own set of limitations that are intrinsic to specific
measurement technique and algorithm. Here we define "Hybrid Metrology" to be the use of any two or more metrology
toolsets in combination to measure the same dataset. We demonstrate the benefits of the Hybrid Metrology on two test
structures: 22nm node Gate Develop Inspect (DI) & 32nm node FinFET Gate Final Inspect (FI). We will cover
measurement results obtained using typical BKM as well as those obtained by utilizing the Hybrid Metrology approach.
Measurement performance will be compared using standard metrology metrics for example accuracy and precision.
Line edge roughness (LER) is an increasingly important issue as lithography scales down. Currently LER is usually
measured using scanning electron microscopy (SEM) tools; however, using optical techniques to measure LER may
have potential benefit due to less resist damage and higher throughput. In this paper, we explore the detection and
potential measurement of LER using dark field spectroscopic reflectometry. We provide a proof of feasibility by
showing LER spectra collected on several different applications, which behave consistently with scattering from
small particles (Rayleigh) and decrease sharply with wavelength. Additionally, the dependence of the spectra on
film thickness bears resemblance to thin film measurements. Finally, we also provide preliminary simulation results
showing similar spectral characteristics to the measured spectra.
This paper discusses a novel methodology of material characterization that directly utilizes the scatterometry targets on
the product wafer to determine the optical properties (n&k) of various constituent materials. Characterization of optical
constants, or dispersions, is one of the first steps of scatterometry metrology implementation. A significant benefit of
this new technique is faster time-to-solution, since neither multiple single-film depositions nor multi-film depositions on
blanket/product wafers are needed, making obsolete a previously required-but very time-consuming-step in the
scatterometry setup. We present the basic elements of this revolutionary method, describe its functionality as currently
implemented, and contrast/compare results obtained by traditional methods of materials characterization with the new
method. The paper covers scatterometry results from key enabling metrology applications, like high-k metal gate (postetch
and post-litho) and Metal 2 level post-etch, to explore the performance of this new material characterization
approach. CDSEM was used to verify the accuracy of scatterometry solutions. Furthermore, Total Measurement
Uncertainty (TMU) analysis assisted in the interpretation of correlation data, and shows that the new technique provides
measurement accuracy results equivalent to, and sometimes better than, traditional extraction techniques.
Scatterometry is a promising method, capable of providing accurate profile information for a large range of applications. However, applying scatterometry to the production environment and applying it to APC is still difficult. In this paper we propose an alternative approach in which we apply a Neural Network to directly correlate scatterometry raw data and the lithography process control parameters. The proposed method is much easier to use than normal scatterometry, and can therefore be applied to APC much faster.
A 9.3 micrometer cutoff 320 X 256 quantum well infrared photodetector (QWIP) based thermal camera has been demonstrated as a laboratory set-up configuration. The development of the QWIP arrays and system integration is described. Performance analysis of systems which are based on QWIP arrays were performed to evaluate the potential of 320 X 256 and 640 X 480 QWIP array to be a candidate for future mid-end and high-end thermal imager.
We present a model for QWIP-based thermal imagers which allows us to study the effects of the main system parameters on system performance. We use the model to illustrate some of the issues involved in choosing system parameters using a sensitivity analysis. We then present a methodology for choosing the optimal system parameters which takes the constraints presented to the system, such as cost, as an integral part of the model. We propose the use of a benefit- function and a cost-function that allow us to measure the cost-benefit ratio for every system. We use this ratio as the merit figure of the system and optimize for maximal cost- benefit.
As second generation FLIR systems become a reality the need for a reliable, high performance, moderately priced matrix arrays in the 8 - 12 micron atmospheric window becomes a real demand. At the same time, the remarkable advancement of QWIP technology over the past few years makes it one of the best candidates for such applications that suffice in the resolution provided by 320 by 256 pixel arrays. According to its fast advancement it could be expected that in the near future also the requirements of high-end applications will be met by QWIP technology. In light of this potential, the QWIP program in EL-OP was recently started in order to develop in- house QWIP technology and demonstrate 320 by 256 pixel image. Additionally we take part in scientific activities in a joint project with leading Israeli university groups. Preliminary results are presented, including the fabrication of QWIP arrays and measurement of single detectors. Measurement results show D* greater than 5 X 1010 Jones and responsivity approximately equals 0.5 A/W. Additionally, an optimization method for quasi-random scattering arrays is briefly presented.