In this paper, we demonstrate how understanding and controlling lithography through etch, using appropriate integrated metrology, can improve process results, reducing across-wafer CD variability. A spectroscopic CD tool was used to generate CD, profile, and film thickness information from wafers exposed on a 248 nm ASML track/scanner cluster. Using this data, detailed intrafield and interfiled wafermaps were generated. Based on this information, dose, focus, and intensity uniformity corrections were fed back to the track/scanner cluster as offsets for subsequent exposures. In parallel and as a complement to this control loop, CD and profile information was also fed forward to a Lam 2300 Versys Star silicon etch system as input for the etch process optimization step. Following etch, the wafers were moved into the integrated CD metrology module on the etch platform, whereupon post-etch CD/profile measurements were made to verify the effect of the lithography correction, effectiveness of optimized etch process parameters, and magnitude of the lithography-to-etch CD bias.
To extend KrF lithography below the 180nm SIA design rule node in manufacturing, an advanced DUV step and scan system utilizing a lens with an NA up to 0.7 will be required to provide sufficient process latitude. Towards the SIA's 150nm design rule node, manufacturing challenges for 248nm lithography include contact hole printing, iso-dense bias control and adequate across the field CD uniformity. All will benefit from higher NA lenses. In the paper, result obtained on a PAS 5500/700B DUV Step and Scan system are presented. The system design is based on the PAS 5500/500 with a new 0.7NA Starlith lens, AERIAL II illuminator and ATHENA advanced alignment system. Imaging of dense and isolated lines at 180nm, 150nm and below as well as 180nm and 160nm contact holes is shown. In addition to imaging performance, image plane deviation, system distortion fingerprints, single-machine overlay and multiple-machine matching results are shown. Using the ATHENA alignment system, alignment reproducibility as well as overlay result on CMP wafers will be shown. It is concluded that this exposure tool is capable of delivering imaging and overlay performance required for mass production at the 150nm design rule node, with potential for R and D applications beyond.
Conference Committee Involvement (2)
Data Analysis and Modeling for Process Control
26 February 2004 | Santa Clara, California, United States
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.