Determination of Factors Affecting HRTEM Gate Dielectric Thickness Measurement Uncertainty

Published

September 1, 2003

Author(s)

J H. Scott

Abstract

Because high-resolution transmission electron microscopy (HRTEM) relies on a complex contrast mechanism to produce images of gate dielectric films in cross section, there are many factors affecting the uncertainty of thickness measurements based on these images. A preliminary survey revealed approximately 50 parameters that affect the uncertainty in a gate dielectric dimensional metrology experiment using HRTEM, along with approximately 1,200 two-term interactions and almost 20, 000 three-term interactions. Using established design-of-experiment (DEX) methodologies, I performed a screening experiment based on a 2IV(8-4) fractional factorial design to determine which factors has the greatest impact on the absolute error of the thickness measurements. Absolute error was determined by simulating HRTEM micrographs using a multislice calculation. The model used for the simulation consisted of a variable SiO2 film approximately 2 nm thick positioned between two pieces of crystalline Si. This approximation to a gate stack was built atom-by-atom using commercial molecular modeling software supplemented with custom Tcl scripts to assemble the gate structures from simpler primitives. By varying the molecular model, sample parameters such as crystallographic orientation, film thickness, density, and along-beam thickness can be varied precisely. Instrument parameters and details of the imaging conditions are inputs to the multislice calculation, a simulation technique that has been vetted by the microscopy community and has been in use for decades.

Proceedings Title

International Conference on Characterization and Metrology for ULSI Technology | | Characterization and Metrology for ULSI Technology: 2003 International Conference on Characterization and Metrology for ULSI Technology | AIP

Volume

683

Conference Dates

March 1, 0024

Conference Title

AIP Conference Proceedings

Pub Type

Conferences

Keywords

Accuracy, Gate Dielectric, Thickness measurement

Citation

Scott, J. (2003), Determination of Factors Affecting HRTEM Gate Dielectric Thickness Measurement Uncertainty, International Conference on Characterization and Metrology for ULSI Technology | | Characterization and Metrology for ULSI Technology: 2003 International Conference on Characterization and Metrology for ULSI Technology | AIP (Accessed May 11, 2024)