3D NAND flash memory stacks cells vertically in multiple layers. One of the critical processes in chip-making is slit trench landing control since the word-line gate replacement of silicon nitride films and the isolation of plural memory blocks are through the means of slit structure. However, during the gate of silicon nitride removal in slit trenches, the architecture of memory blocks may collapse due to the lack of sufficient supporting patterns surrounding the slit trenches. For better silicon nitride removal control, there are various irregular patterns of dummy pillars (PIL) designed in as supporting structures to provide better mechanical property, which can prevent memory blocks from collapsing while removing silicon nitride in gate replacement processing. Hence, an effective measurement is needed to indicate the bottom shifting of PIL during the etching recipe optimization. In this work, we demonstrate the deployment of small angle X-ray scattering (SAXS) technology with global tilt extraction (GTE) that successfully predicts PIL landing location displacement, which matches destructive gauging data. GTE is a modeless method to determine global tilt, i.e., center line shifting (CLS) of the bottom relative to the topmost on the target pattern. GTE is proven to be a reliable method for in-line process monitoring as well as for use in PIL etching recipe optimization for 3D NAND development.
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.