ECE/ChBE 4752

Fall 2007

Guidelines for the Diffusion Report

Your diffusion report should contain the usual items, including process steps, observations, and results, for ALL of the diffusions that you did in the laboratory. This includes the p-well, the p+ source/drain, and the n+ source/drain. Be sure to describe both predeposition and drive-in steps for all of the diffusions, even if the drive-in occurs simultaneously with another high temperature step such as oxidation.

In addition to the usual items, this report must contain a substantial computer analysis and analytical (i.e., 'by hand') component. For each diffusion, you have measured a sheet resistance (or if you haven’t, Laureen has – get the typical values from her). As we discussed in class, sheet resistance, junction depth, and doping profile are related. Therefore, for each diffusion (remember, that means both for predeposition as well as for drive-in of each diffusion), you should do the following in your lab report:

1. Calculate the junction depth using Fickian diffusion (i.e., the erfc and Gaussian profiles we discussed in class).

2. Estimate the junction depth from your results of #1, together with Irvin’s curves and the measured value of sheet resistance (see the ‘diffusion figures’ section of the class website).

3. Find the junction depth using SUPREM.

4. Use SUPREM to calculate the expected sheet resistance (note you can either get SUPREM to integrate this for you or you can use the integral formula we discussed in class together with information on the dependence of carrier mobility on concentration posted on the class website).

5. Compare the SUPREM-calculated sheet resistance with what you measured in the laboratory.

Ideally, all of these should agree (with the exception of the n+ source/drain – why?) If they do not, explain any differences.

THE DIFFUSION REPORT WILL BE DUE ON THURSDAY NOVEMBER 8^TH

AT THE BEGINNING OF CLASS