Method for manufacturing a thin film actuated mirror having a stable elastic member

A method for manufacturing an array of thin film actuated mirrors for use in an optical projection system, the method comprising the steps of:

• providing an active matrix comprising a substrate having an array of connecting terminals formed thereon;
• forming a thin film sacrificial layer on top of the active matrix;
• depositing an elastic layer on said thin film sacrificial layer by a LPCVD process, wherein a ratio of a mixture of source gases is changed during deposition such that a lower elastic layer and an upper elastic layer are formed, said lower and upper elastic layers having different stoichiometries;
• forming a lower thin film electrode on top of the elastic layer;
• forming an electrodisplacive layer on top of the lower thin film electrode;
• forming an upper thin film electrode on top of the electrodisplacive layer, said upper thin film electrode being made of a light reflecting material;
• patterning the upper thin film electrode, electrodisplacive layer, lower thin film electrode and the elastic layer, thereby forming an array of actuating structures and exposing said thin film sacrificial layer;
• covering the array of actuating structures with protection layer;
• and
• etching away said thin film sacrificial layer.