  Development of small pixels for high resolution image sensors implies a lot
of challenges. A high level of performance should be guaranteed whereas the
overall size must be reduced and so the degree of freedom in design and
process. One key parameter of this constant improvement is the knowledge and
the control of the crosstalk between pixels. In this paper, we present an
advance in crosstalk characterization method based on the design of specific
color patterns and the measurement of quantum efficiency. In a first part, we
describe the color patterns designed to isolate one pixel or to simulate
un-patterned colored pixels. These patterns have been implemented on test-chip
and characterized. The second part deals with the characterization setup for
quantum efficiency. Indeed, the use of spectral measurements allows us to
discriminate pixels based on the color filter placed on top of them and to
probe the crosstalk as a function of the depth in silicon, thanks to the photon
absorption length variation with the wavelength. In the last part, results are
presented showing the impact of color filters patterning, i.e. pixels in a
Bayer pattern versus un-patterned pixels. The crosstalk directions and
amplitudes are also analyzed in relation to pixel layout.
