(image) (image) [Previous] [Next]

Predictive and Efficient Modeling of Hot Carrier Degradation with Drift-Diffusion Based Carrier Transport Models

5.2 Simulation Framework

(image) (image)

Figure 5.2: The adaptive mesh for a near interface device section of the nLDMOS (left figure) and the pLDMOS (right figure) transistors with the built-in potential represented by the color map.

The carrier energy distribution function is sensitive to details of the doping profiles and to the device architecture. The device structure of the n- and pLDMOS transistors was generated by the Sentaurus Process simulator [198] which was coupled to the device simulator Minimos-NT [124, 125] and calibrated self-consistently in order to reproduce the characteristics of the fresh transistor. An important ingredient for reliable and adequate simulations of the carrier DF with ViennaSHE is a proper mesh. It is important to emphasize that even with the DD scheme, modeling of such a large LDMOS transistor with a complicated geometry is a non-trivial task. On the one hand the required mesh is expected to be fine enough especially near the \( \mathrm {Si}\slash \mathrm {SiO_{2}} \) interface, at the bird’s beak, and close to other important device regions. On the other hand, the mesh should only contain a moderate number of elements in order to ensure a reasonable simulation time. For instance, such a mesh can be coarse in the Si bulk. To achieve these goals, the highly adaptive meshing framework ViennaMesh is used [199]. ViennaMesh generates meshes based on the built-in potential, see Figure 5.2 [26]. The resulting mesh has a fine resolution in important regions, a sufficiently low density in less important regions and contains about 11,000 elements. ViennaMesh proves to be beneficial not only for SHE simulations, but also also for the DD simulations in Minimos-NT.