The rate of silicon oxidation depends in part to the orientation of the silicon crystals, as previously discussed in Section 2.2.1 and Section 2.3. Orientation effects can be observed, when oxidizing a trench in a (100) silicon surface. A thicker oxide is expected on the sidewalls since their orientation is (110). This effect is implemented in the presented LS model framework.
The effects of silicon orientation are visible in Figure 6.3 where the (110) sidewalls are seen as having a thickness greater than that of the (100) surfaces. The corners also experience pinching due to the amorphous nature of the oxidant diffusion through the oxide.