Jacek Lagowski

The Present Status and Recent Advancements in Corona-Kelvin Non-Contact Electrical Metrology of Dielectrics for IC-Manufacturing

Non-contact electrical metrology offers a fast and cost saving monitoring of dielectrics in IC manufacturing process. This corona-Kelvin measuring technique has entered the maturity stage with about 400 tools installed in silicon IC-fabs. We discuss recent advancements that broaden the spectrum of monitoring parameters and enhance the precision of these measurements. We also discuss the current ongoing extension of corona-Kelvin metrology to the micro scale measurement on sites as small as 30µm x 30µm. This opens new possibilities for non-contact electrical testing of product wafers, rather than expensive process monitor wafers. Micro-measurement is illustrated using flash memory ONO structures and corona induced programming and erasing.

Non-Contact C-V Technique for high-k Applications.

This non-contact high-k monitoring technique is based on a differential quasistatic C-V that is generated using time- resolved metrology combining corona charging and contact potential difference (CPD) measurements. The technique incorporates transconductance corrections that enable measurements in the high field range (lOMV/cm) required for extraction of large dielectric capacitance corresponding to ultra-low equivalent electrical oxide thickness (EOT) down to the sub-nanometer range. It also provides a means for monitoring the flat band voltage, VFB, the interface trap spectra, DIT, and the total dielectric charge, dQTOT- This technique is seen as a replacement for not only MOS C-V measurements but also for mercury-probe C-V. EOT measurement by the differential corona C-V has a major advantage over optical methods because it is not affected by water adsorption and molecular airborne contamination, MAC. These effects have been a problem for optical metrology of ultra-thin dielectrics. The presented results illustrate the application of the technique to state of the art gate dielectrics, including Si-O-N and HfO2.

Recent Advancement in Charge and Photo-Assisted Non-Contact Electrical Characterization of SiC, GaN, and AlGaN/GaN HEMT

The charge-based corona-Kelvin noncontact metrology, originally developed for Si IC fabrication, has recently been extended to wide energy gap semiconductors. We discuss principles of this extension and key applications, namely: high precision dopant measurement on SiC and GaN; two-dimensional electron gas characterization in AlGaN/GaN HEMT structures; interface and dielectric characterization on epi-layers with SiO2, SiN and Al2O3; comprehensive interfacial instability characterization of oxidized SiC; and whole wafer mapping of defects with a charge-assisted surface voltage technique. This powerful set of measurements is performed without fabrication of any test structures or electrical contact. Corresponding commercial tools are currently being introduced. Based on the historical example of silicon IC, we believe that this approach shall offer enhanced testing for research and for manufacturing process control with reduced cost and fast data feedback benefiting the wide-bandgap device technology.