A semiconductor integrated circuit production method prepares an SOI layer thickness database that correlates measurement data of each SOI layer thickness with each SOI substrate identification data. The production method extracts the measurement data for each SOI substrate from the SOI layer thickness database, and carries out layer thickness adjustment surface treatment for the SOI substrates based on these data. A semiconductor integrated circuit production device includes an SOI layer thickness database storage unit for storing the SOI layer thickness database, and a layer thickness adjustment conditions control unit for extracting the measurement data for each SOI substrate from the SOI layer thickness database and deciding conditions for the layer thickness adjustment surface treatment based on these data. The semiconductor integrated circuit production device also includes a surface treatment unit that adjusts SOI layer thickness by carrying out the surface treatment on the SOI layers in accordance with the decided conditions.