Abstract: A field transistor monitoring pattern has two active areas, i.e., a source region and a drain region, spaced apart from each other by an STI area intervening therebetween. The STI area is generally narrower than each active area. The monitoring pattern further has two gate patterns, each having a gate trunk and at least one gate branch extending from the gate trunk and crossing over both active areas. The monitoring pattern can be used to check an isolation property of the STI area by applying the same voltages to both gate patterns and then measuring leakage current between both active areas. Additionally, by applying different voltages to both gate patterns and detecting leakage current therebetween, the monitoring pattern can monitor unfavorable dimple defects potentially produced in the STI area.