waveguide dimensions, given by fabrication tolerances, cause larger shifts. In the case of the deepest etching depth ( d = 1 . 2 $_{m}$m), it is observed that the change of the waveguide shape is even stronger. Here, the tapering of the trench was insufficient to compensate for the sidewall bending induced by the tensile stress of the Si$_{3}$N$_{4}$ layer. This effects the final closure of the trench when the deposited Si$_{3}$N$_{4}$, which grows from the two side walls, meet in the middle. As a result, the trench is not filled entirely with Si$_{3}$N$_{4}$ as can be seen in Fig. 3(c). In future, we will compensate for this effect by applying a stronger positive taper to the sidewall of the trenches. During the fabrication, a large number of waveguides and waveguide circuits were obtained with the described technique covering a total of six wafers (100 mm diameter) and not a single crack was observed in the Si$_{3}$N$_{4}$ layers. This clearly indicates that, using our novel approach, crack-free Si$_{3}$N$_{4}$ waveguides with a width of up to 0.9 $_{m}$m can be fabricated. The propagation losses are an essential characteristic for integrated waveguides, since they are critical for the design of devices such as micro-resonators. By measuring the transmission of a broadband light source through the waveguides, the propagation losses were determined. The broadband light from a superluminescent diode with a center wavelength of 1560 nm and a spectral bandwidth at full width at half maximum of 45 nm was used. The light was injected and collected using lensed fibers (2 $_{m}$m spot size at 1550 nm), while the input polarization was controlled to excite the quasi-TM mode which is primarily polarized along the y-direction (see Fig. 2(d)) of the waveguides using an in-line optical fiber polarization controller. The transmitted power was measured for three etching depths, 0.8 $_{m}$m, 1.0 $_{m}$m, and 1.2 $_{m}$m, and for four different propagation lengths, using spiral waveguides with lengths of 2.30 cm, 3.89 cm, 6.90 cm, and 10.48 cm and of various widths. The transmission as a function of waveguide length is shown in Fig. 4(a), and from this data, the propagation loss coefficient is determined to be 0.37 dB/cm ( d = 0 . 8 $_{m}$m, blue), 0.45 dB/cm ( d = 1 . 0 $_{m}$m, red), and 1.37 dB/cm ( d = 1 . 2 $_{m}$m, black), while w 3. Characterization