ECE 6450 Homework 2 NOTE: Some reference materials including tables, figures etc. .. handed out in class or in your text may be needed to solve these problems. Analog Devices has asked you to fabricate a pnp Bipolar Junction Transistor (BJT) in a p-type, Silicon wafer, uniformly doped to a level of 10 15 cm-3 . The device designer has specified a pnp structure as illustrated with the fabrication to begin with the base diffusion first followed by the emitter diffusion. For good BJT performance, the designer has specified that the Base-Collector junction be 3 um from the wafer surface, while the Base-Emitter junction (10 16 cm-3 doped at the junction) is to be 1 um from the surface. Ignore all edge diffusion effects (i.e. consider all diffusions to be planar resulting in a 1D diffusion and assume n<<n i and p<<n i due to very high temperatures resulting in very high n i ). Base: 1.) The base is to be done first (before the emitter-see step 2) by a predeposition and drive in (not a “2 step diffusion” but 2 individual steps. This means use solutions to the diffusion
This is the end of the preview.
access the rest of the document.