TSMC chose Arizona for its chip making facility because Arizona already has an ecosystem of  equipment suppliers, fabrication units. Having an ecosystem makes it cost effective. Also Arizona is home to other chip companies like Intel, NXP, ON semiconductor, Qualcomm, Microchip, Broadcom and Benchmark Electronics. Also geopolitics then worked in favor of Arizona state. Arizona is a Republican state then and under Trump presidency would have given more incentives for the chip makers establishment.