One more thing, multi-finger layout is NOT necessarily for matching.
If you have just ONE single transistor, you need not do matching. Then should we use multi-finger layout?
if you don't need to reduce parasitic resistance, I'd recommended you draw a WHOLE BIG transistor and it is better. Photomask misalignment is an absolute value. Say the photomask always mis-align by 0.1um. If you have one single transistor, then say 10um, your final width is 9.9um. if you have 4 multi-finger transistor of each 2.5um, then you mis-align each by 0.1um, then the final mis-align is 0.1x4=0.4um, which is a lot larger than a WHOLE BIG transistor. So, when u design or decide the layout, be sure you understand the backend first