Phase Profilometry (PP) has been proposed for in-situ/in-line critical dimension and profile measurements. This is usually accomplished by using rigorous electromagnetic theory to simulate the optical responses of gratings with different profiles, and by using spectroscopic ellipsometry/reflectometry to measure 1-D gratings. In this paper, phase profilometry is applied to the lithography process for cross-sectional profile extraction metrology. A focus-exposure experiment was conducted using Sematech's 193 nm lithography tool. Comparison between the measurements from CD-SEM, CD-AFM and PP are discussed and explained.
With the advent of deep sub-micron semiconductor technology, metrology for metal interconnects becomes more critical. In addition to the line width, information about the height and the sidewall profile is needed to ensure good circuit performance. Conventional metrology tools such as CD SEMs and AFMs are either unable to measure the profile, or too slow for production process control. Scatterometry is a promising candidate as in situ, full-profile metrology tool. In this method, scattering of broadband light (240 nm to 760 nm) on periodical structures is simulated by approximating the structure with a finite series of Fourier expansion terms. By comparing the measured spectrum and the simulated spectra for various possible profiles in a precalculated library, the profile can be extracted. Previous work has shown good results on resist structures. For metal structures, however, more diffraction orders need to be included to accurately simulate light scattering. In this study, a library for 0.22 micrometer line and 0.44 micrometer space metal grating structures is generated using 31 orders. The profiles of metal grating structures of the same size are extracted using this library. Our data shows that the correlation between CD-SEM and scatterometry-based profile extraction appears to be related to the sidewall angle of the profile. These discrepancies will be analyzed and discussed.
Scatterometry is a one of the few types of metrology that has true in-situ potential for deep submicron CD and profile analysis. To date, commercial prototypes have been used to establish scatterometry based on single wavelength, multiple incident angle inspection. We extend this idea by deploying specular spectroscopic scatterometry (SSS). Conventional scatterometry is designed to measure either many diffraction orders or variable incident/collection angle at a single wavelength. Specular spectroscopic scatterometry is designed to measure the 0th order diffraction responses at a fixed angle of incidence. Specular spectroscopic scatterometry can make direct use of the existing spectroscopic ellipsometry equipment. We show that SSS provides an accurate, inexpensive, and non-destructive CD metrology solution.
As the semiconductor industry moves into the deep submicron range, the costs associated with wafer processing are increasing rapidly. This calls for improved simulation capabilities that provide information for meaningful 'what if' analysis. This work proposes a common methodology for extracting information from FTIR, dissolution rate monitor and ellipsometry measurements, to be ultimately used for the calibration of commercial lithography simulation tools. Using global optimization techniques, this approach uses cross-section CD data available in fabs to tune the simulation engine, thus giving it the predictive capabilities that could potentially improve yield ramp rates and hence reduce development costs. Results of this framework for a commercial Shipley resist are presented.
KEYWORDS: Data modeling, Photoresist processing, Chemically amplified resists, Lithography, Polymers, Systems modeling, Molecules, Process modeling, Interfaces, Computing systems
High activation energy, chemically amplified resist systems exhibit a 4 percent to 15 percent volume shrinkage during the post-=exposure bake process. Current lithography process simulators do not take this volume shrinkage into account, thus violating the continuity equations used to model the process. This work aims at describing the kinetics of the post-exposure bake process by tracking the volume shrinkage observed in high activation resists. A dynamic model is derived and corroborated with experimental results for Shipley UV5. A global simulation technique is then used in conjunction with the models to extract the lithography parameters for these resists.
KEYWORDS: Data modeling, Chemically amplified resists, Photoresist processing, Systems modeling, Polymers, Process modeling, Lithography, Molecules, Interfaces, Computing systems
Improvements in the modeling of chemically amplified resist systems are necessary to extract maximum possible information form limited experimentation. Previous post- exposure bake models have neglected volume shrinkage, thus violating the continuity equations used to model the process. This work aims at describing the kinetics of the post-exposure bake process by tracking the volume shrinkage observed in both low and high activation energy resists. Both static and dynamic models are derived and corroborated with experimental results for Shipley UV5 and AZ 2549 resists. A global simulation technique is then used in conjunction with the models to extract the lithography parameters for these resists.
SC831: Introduction to Scatterometry Metrology: Theory and Application
This course provides an introduction to the theory of scatterometry metrology, as well as its application for process control in semiconductor manufacturing. Both the software and the hardware portions of the scatterometry system are covered. Scatterometry is an optical method to measure profiles (CD, sidewall angle, height) features on semiconductor wafers and photomasks. Scatterometry is becoming widely adopted for production-worthy metrology as an alternative and complementary tool to CD-SEM and AFM.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.