Self-assembling of patterned nanostructures in solution-processed thin films with multiphase block-copolymers is possible. Generation of small and well-defined regular structures directly from single-phase polymer films is challenging. Here, 2-dimensional (2D) patterned array in single-phase polymers was self-assembled by a solution process. One-dimensional spinodal precipitation with a characteristic wavelength was created along a pinned contact line of the drying solution to form a one-dimensional periodic structure (1DPS) via geometry and concentration confinements. The latter was uncovered from the liquid by sequential depinning and repinning of the contact line. A new 1DPS with an inherited phase re-emerged and triggered depinning and repinning. The process was self-repeated and a 2D array formed with a tuneable lattice type and parameters, which was governed by the interference of two concentration-modulated waves.