An engineer wants to form a shallow boron-doped source/drain junction for an advanced technology.
The manager wants to know whether the company should buy an inexpensive batch furnace and achieve the required junction depth using a low-thermal budget anneal (one hour at 800°C) or an expensive single-wafer RTA (Rapid Thermal Annealer) using a high-temperature anneal.
a. Calculate the time required to achieve the target junction depth if the annealing temperature is 1050°C in the RTA.
b. Make a crude estimate (√(Dt) approximation) of how far the dopants move during these anneals
c. Now, consider that the boron is introduced using an implant and that Transient Enhanced Diffusion (TED) due to the implant will be important. Using the charts for the expected enhancement in diffusivity and the time TED lasts calculate how far the dopants move at each temperature.
d. Which anneal would you recommend?