6.2 Documentation and Training

The simulation results of the semiconductor process flow contain the information of the geometry of the simulated device (e.g., CMOS-Transistor) and the complete dopant distribution. This information is usually needed by process engineers but is very difficult, costly, or even impossible to obtain by other methods (e.g., SIMS, TEM). Combining the information of the process simulation and the process flow description results in a documentation of the process of very high quality. This information obtained by process simulation, which is usually only available for TCAD-Engineers, can be easily shared with process engineers, if a format with cross platform compatibility is used. One data format which fulfills the necessity of cross platform compatibility is the Hypertext Markup Language (HTML). Furthermore, especially during the development phase of a new process it is necessary that the simulation results can be transformed very quickly into HTML. A swift transformation of the process simulation results (which are usually in a platform dependent format or only viewable by special TCAD software) to HTML is achieved by a PERL script which extracts the relevant simulation results and links them with the description of the respective process step. The information of a diffusion or oxidation process recipe often consists of several dozens single process steps. This huge amount of information is best analyzed graphically as process temperature and gas flows versus time. Another information often needed by process engineers is the temperature versus time of the complete process which allows e.g. to figure out quickly the most relevant thermal process steps. Figure 6.5(a) shows a typical example for the documentation of a single diffusion program. Figure 6.5(b) demonstrates the documentation of a dedicated step during the processing of a bipolar transistor in a BiCMOS process technology. It shows the cross-section of the transistor after contact mask etch. Figure 6.5(c) indicates the total thermal profile of a process flow. The falling red line symbolizes the temperature of every diffusion recipe during the whole process. The time is the accumulated diffusion time of the diffusion programs. Figure 6.5(d) shows the one-dimensional cross-section through the source contact of a CMOS transistor.

Figure 6.5: (a)Example of diffusion program documentation. (b)Cross section through a bipolar transistor. (c)Thermal budget of a process flow. (d)One dimensional doping cross section

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