We have previously reported that columnar-structures were formed in electron beam (EB) deposited and DCmagnetron sputtered Mo-Si layered synthetic microstructures (LSMs). The columnar structures reduced x-ray reflectivity by roughing layer interfaces of the LSMs. We here investigated the conditions to suppress columnar structure formation, by varying the substrate temperature (T9) in EB deposition and the argon pressure (PAT ) in D C- and RF-sputtering. In the EB deposited LSMs, the columnar structure disappeared and almost uniform LSMs were obtamed both at T□ 400°C and T9< -155°C. In the DC- and RF-sputtered LSMs, the columnar structure formation was suppressed by lowering PAr. The measured x-ray reflectivity of the LSMs increased according to the suppression of the columnar structure formation.