1. A method for semiconductor device production process monitoring, the method comprising the steps of: during the production process of the semiconductor device, obtaining a scanning electron microscopy (SEM) image of a target pattern formed on a sample through a predetermined process; obtaining a feature amount of the obtained SEM image of the target pattern; estimating a cross-sectional shape of the target pattern by comparing (a) the obtained feature amount of the obtained SEM image of the target pattern to (b) a database that preliminarily stores a first learning data representing correlations between (1) data of feature amounts of images obtained from SEM images obtained from various three-dimensional (3D) shape patterns, and (2) data obtained by measurement of cross-sectional shapes of the 3D shape patterns; estimating a process condition of the target pattern by comparing (a) the obtained feature amount of the SEM image of the target pattern to (c) a database that preliminarily stores a second learning data representing correlations between (1) data of feature amounts of images obtained from SEM images obtained from various 3D shape patterns, and (3) data of process conditions when the various 3D shape patterns are formed; determining whether the estimated cross-sectional shape of the target pattern satisfies a preliminarily set specification through comparison to the specification, and if the estimated cross-sectional shape of the target pattern does not satisfy the preliminarily set specification, calculating a process condition adjustment amount by using the estimated process condition of the target pattern; wherein the process condition adjustment amount provides feedback to the production process of the semiconductor device.