Investigating Diffusion in Silicon Wafers: A Study of Doping and Sheet Resistance Measurement.

The main objective of the experiment is to calculate junction depth of a silicon wafer after pre deposition and two drive-in steps at 1000 ºC and 1100 ºC. Experimental values were compared with the calculated values and percentage differences were evaluated. Four-point probe was used to measure the sheet resistance. Spin on dopants were used, besides the tube furnace for heating purposes. Resistivity of silicon as a function of dopant concentration and Irvin’s curves were used for the calculations, besides the other formulas mentioned in the report. Predeposition was done for 900 seconds, and drive-in steps were done for further 900 and 1800 seconds at 1000 ºC and 1100 ºC respectively. The wafers were cleaned using acetone and IPA, and HF dip. Predeposition and drive-in 2 values have percentage difference between calculated and experimental 33.9% and 36.9% respectively due to presence of native oxide layers, impurities or possibly for considering a fixed constant value of dopant concentration of P505 to be 0.45*10 ²⁰ atoms/cm ^− 3 . Drive-in 1 had percentage difference of 11.6%, which is within acceptable range for variation between the calculated and experimental results. The results were tabulated and graphed using origin pro to give a better visual representation of the results.