  In this paper we present a novel fabrication technique for silicon nitride
(Si3N4) waveguides with a thickness of up to 900 nm, which are suitable for
nonlinear optical applications. The fabrication method is based on etching
trenches in thermally oxidized silicon and filling the trenches with Si3N4.
Using this technique no stress-induced cracks in the Si3N4 layer were observed
resulting in a high yield of devices on the wafer. The propagation losses of
the obtained waveguides were measured to be as low as 0.4 dB/cm at a wavelength
of around 1550 nm.
