Defect Specific Lifetime Analyzer [DSLA©]
E. Kamieniecki, J. App. Physics 112, 063715 (2012); Patents: US 7,898,280,B2; US 8,896,338,B2
This deficiency of existing metrologies, and specifically the Surface Charge Analyzer which requires the use of monitor wafers is addressed by non-contact Defect Specific Lifetime Analyzer (DSLA) which is based on the proprietary analysis of the time dependent density of optically generated charge carriers, DSLA simultaneously differentiates properties of the surface and bulk of semiconductors focusing on, depending on the probe configuration, on the surface or bulk regions. Unlike Surface Charge Analyzer and Surface Charge Profiler, DSLA operates at wide probe-semiconductor distance making it particularly useful for on-line process monitoring of product wafers in microelectronic and wide bandgap semiconductor device manufacturing. The probe-semiconductor gap can be tailored to process requirements and configuration of the probe can be adjusted enhancing monitoring of the process parameters critical for device performance e.g. by separating contacts or bulk characteristics of the devices.
Since DSLA measurements do not involve current flow and the collection of charges at the electrodes but are solely based on the absorption of the RF radiation, DSLA can be used for the characterization of monocrystalline, polycrystalline, and amorphous materials.
The capabilities of the DSLA in monitoring of the wide bandgap semiconductor device fabrication are illustrated below for the photo-current radiation detectors. In this application DSLA not only identified point and extended defects that directly affect performance of the detectors but also showed that electrode formation is a critical factor affecting reproducibility of the fabrication process. In the defect enhanced mode of operation the DSLA signal increases with density of defects which may be particularly important in evaluation of compound semiconductor wafers (see Physics of Inductive Detection) .
