8.25 Sspd_chapter 6_part 7_introduction to athena 6_process simulator  (Page 5/7)

For a detailed description of ion implant model selection, see Chapter 3: “SSUPREM4 Models”, Section 3.5:“Ion Implantation Models”.

You can specify tilt and rotation angles of the ion beam. Positive tilt angles correspond to the ion beam coming from the top left. Specifying the rotation angle makes sense only for non-zero tilt angles. Zero rotation means that the ion beam vector lies in the plane parallel to the 2D simulation plane. 90° rotation means that the ion beam vector lies in the plane perpendicular to the simulation plane.

Selecting Continual rotation causes SSUPREM4 to rotate the wafer, i.e., implantation will be performed at 24 different rotation angles from 0 to 345°, in increments of 15°.

There are several damage models available in SSUPREM4. These models allow you to estimate distributions of various defects generated after ion implantation. For more details about the damage models and their effect on subsequent diffusion, see Chapter 3: “SSUPREM4 Models”, Section

7.7.6:“Ion Implantation Damage”.

When the Monte Carlo model is selected, you can specify several additional optional parameters (See Figure 7.36). The first three parameters are related to the Damage model (Point defects, {311}-clusters, and dislocation loops). The three others control Monte Carlo calculation (initial random number, number of trajectories, and smoothing). See Table 7.6 for a quick reference of ATHENA implant models.

Table 7.6. ATHENA Implant Model Reference

Figure 7.36. ATHENA Implant Window continued on next page

Figure 7.36. ATHENA Implant Window

7.7.7 Simulating Diffusion

Simulation of thermal process steps is a focal point of SSUPREM4. The hierarchy of diffusion and oxidation models is described in this chapter and in Chapter 3: “SSUPREM4 Models”, Sections 3.1: “Diffusion Models” and 3.3: “Oxidation Models”. This section will demonstrate how to set different parameters and models of diffusion, oxidation and silicidation. The last process will take place only if at least one refractory metal or silicide layer is present in the structure.

The parameters and models of a diffusion/oxidation step can be prepared from the ATHENA Diffuse Menu. (Figure 7.37).

Figure 7.37. ATHENA Diffuse Menu.

To open this menu, select Process→Diffuse... in the Deckbuild Commands menu. The Diffuse menu has four sections. Only the Time/Temperature and Ambient fields appear initially. The Impurities and Models fields appear only when the corresponding check boxes are selected.