  The Hubble diagram of type-Ia supernovae (SNe-Ia) provides cosmological
constraints on the nature of dark energy with an accuracy limited by the flux
calibration of currently available spectrophotometric standards. The StarDICE
experiment aims at establishing a 5-stage metrology chain from NIST photodiodes
to stars, with a targeted accuracy of \SI{1}{mmag} in $griz$ colors. We present
the first two stages, resulting in the calibration transfer from NIST
photodiodes to a demonstration \SI{150}{Mpixel} CMOS sensor (Sony IMX411ALR as
implemented in the QHY411M camera by QHYCCD). As a side-product, we provide
full characterization of this camera. A fully automated spectrophotometric
bench is built to perform the calibration transfer. The sensor readout
electronics is studied using thousands of flat-field images from which we
derive stability, high resolution photon transfer curves and estimates of the
individual pixel gain. The sensor quantum efficiency is then measured relative
to a NIST-calibrated photodiode. Flat-field scans at 16 different wavelengths
are used to build maps of the sensor response. We demonstrate statistical
uncertainty on quantum efficiency below \SI{0.001}{e^-/\gamma} between
\SI{387}{nm} and \SI{950}{nm}. Systematic uncertainties in the bench optics are
controlled at the level of \SI{1e-3}{e^-/\gamma}. Uncertainty in the overall
normalization of the QE curve is 1\%. Regarding the camera we demonstrate
stability in steady state conditions at the level of \SI{32.5}{ppm}.
Homogeneity in the response is below \SI{1}{\percent} RMS across the entire
sensor area. Quantum efficiency stays above \SI{50}{\percent} in most of the
visible range, peaking well above \SI{80}{\percent} between \SI{440}{nm} and
\SI{570}{nm}. Differential non-linearities at the level of \SI{1}{\percent} are
detected. A simple 2-parameter model is proposed to mitigate the effect.
