Thanks for your reply.
I tried out the Mone Carlo simulation as you mentioned. The simulation worked but the result seems unrepresenting the matching performance.
I think I might dig into the manual to find out the matching specifications of the process I use.
I am new to this so can you kindly tell me where I might be looking for to find such info?
I am design a current protection circuit in which I want to used a smaller NMOS to mirror the current going through the power transistor. In the schematic simulation, I manage to get the sampling current to be 1/60 of the current going through power mosfet. But I am not sure that when it comes to fabrication, will this 1/60 would be possible to achieve?