In this study, we report a novel method for controlling the shape of a micromachined bridge (clamped-clamped beam) by plasma surface modification. In short, the microbridge can be tuned to either buckle upward or downward using plasma treatment. To demonstrate the feasibility of this approach, NH plasma treatments were employed to control the direction of buckling amplitude for a SiO microbridge. Furthermore, the shape of a buckling microbridge can also be adjusted by the same technique. The buckling profiles predicted by finite element analysis are in agreement with those determined from the measurement. © 2006 The Japan Society of Applied Physics.