Question

1. Find the Seebeck coefficients of Au and Ni from literatures and internet (make sure provide the reference), design a thermocouple microprobe. (40 points): (i) Basic fabrication process flow to make the microprobe (i) Plot the curve relating the temperature change of the probe and the measured voltage from the probe

Answer 1

Seeback coefficient S = -Delta V/Delta T Delta V = -S Delta T for Ni S = -15 for Av S = 6.5 } rightarrow Wikipedia for Ni Delta V = 15 Delta T for Av Delta V = -6.5 Delta T slope = -6.5 \r\n rightarrow Fabrication process is as: (i) Firstly take silicon wafer as a substrate. (ii) then put it in furnace to grow a thick thermal oxide layer at temp 1050 degree C for 150 minutes (iii) oxide layer was patterned by photolithography and after then we etch it by buffered oxide (iv) After that, the exposed regions of silicon were wet etched by KOH solution (25%) at 80 degree C for 1 hour to suspend the micro machered probe. \r\n (v) Then 0.2 um-thick Ti metal was deposited by evaporation as cohesive layer and seed layer. Because it can support a large residual