MOS Capacitor: calculated oxide thickness greater than real

[iria]

Hello,

I have developed MOS capacities, and I have performed CV measurements over them. In the accumulation region the capacity was: 3,04237•E-10 F and the area of the capacitors is 1,7mm. With that I get that the oxide thickness is 328nm When I know that the real oxide thickness is only 200nm. What can cause that?? I cannot understand. I can understand to get less oxide than real, but ... more??

I haven't found any information about this, and I'm sure that the measurements are correct, because they showed the same values through the different MOS that I measured (8 in total).

I hope someone has any idea. I'm desesperated!


Thank you so much!

 

[Vailanor]

The most likely explanation for the discrepancy between your calculated oxide thickness and the real one is that your capacitance measurements were not accurate. This could be due to a number of factors, such as impurities or defects in the oxide layer, non-uniformities in the oxide layer, or other physical processes that can alter the capacitance of the device. Additionally, if you are using a model to calculate the oxide thickness, the model may not accurately reflect the physical structure of the device, which could contribute to the discrepancy. It is also possible that there is an error in the measurement of the area of the capacitor, as this will also affect the calculated oxide thickness.