  The presence of fringing in astronomical CCD images will impact photometric
quality and measurements. Yet its impact on the Vera C. Rubin Observatory's
Legacy Survey of Space and Time (LSST) has not been fully studied. We present a
detailed study on fringing for Charge-Coupled Devices (CCDs) already
implemented on the Rubin Observatory LSST Camera's focal plane. After making
physical measurements and knowing the compositions, we have developed a model
for the e2v CCDs. We present a method to fit for the internal height variation
of the epoxy layer within the sensors based on fringing measurements in a
laboratory setting. This method is generic enough that it can be easily
modified to work for other CCDs. Using the derived fringing model, we
successfully reproduce comparable fringing amplitudes that match the observed
levels in images taken by existing telescopes with different optical designs.
This model is then used to forecast the expected level of fringing in a single
LSST y-band sky background exposure with Rubin telescope optics in the presence
of a realistic time varying sky spectrum. The predicted fringing amplitude in
LSST images ranges from $0.04\%$ to $0.2\%$ depending on the location of a CCD
on the focal plane. We find that the predicted variation in surface brightness
caused by fringing in LSST y-band skybackground images is about $0.6\
\mu\rm{Jy}\ \rm{arcsec}^{-2}$, which is 40 times larger than the current
measurement error. We conclude that it is necessary to include fringing
correction in the Rubin's LSST image processing pipeline.
