Low temperature formed thin film actuated mirror array

A method for the manufacture of an array of M.times.N thin film actuated mirrors, wherein M and N are integers and each of the thin film actuated mirrors includes a light reflecting portion and an actuating portion, for use in an optical projection system, the method comprising the steps of:

• providing an active matrix having a top surface, the active matrix including a substrate with an array of M.times.N transistors and an array of M.times.N connecting terminals;
• forming a thin film sacrificial layer on the top surface of the active matrix;
• removing portions of the thin film sacrificial layer formed around top of each of the connecting terminals in the active matrix;
• forming a second thin film electrode layer on top of the thin film sacrificial layer and the top surface of the active matrix;
• depositing a lower electrodisplacive layer on top of the second thin film electrode layer, wherein the lower electrodisplacive layer is made of a material characterized in that it is crystallographically asymmetric, exhibits no hysteresis, and is formed at a temperature ranging from 200.degree. C. to 300.degree. C.
• forming an intermediate electrode layer on top of the lower electrodisplacive layer;
• patterning the intermediate electrode layer in a columnar direction to produce M number of patterned intermediate electrode layers, wherein each of the patterned intermediate electrode layers is disconnected from each other and covers a portion of the lower electrodisplacive layer in such a way that the portion encompasses the connecting terminals in a same column;
• depositing an upper electrodisplacive layer, made of the same material as that of the lower electrodisplacive layer, on top of the lower electrodisplacive layer with the patterned intermediate electrode layers located therebetween;
• patterning the upper and the lower electrodisplacive layers in the columnar direction until the second thin film electrode layer is exposed to produce a patterned structure including M number of patterned layers and a corresponding number of exposed second thin film electrode layers to thereby define the actuating portion and the light reflecting portion in each of the thin film actuated mirrors, wherein each of the patterned layers corresponds to the actuating portion in each of the thin film actuated mirrors, is disconnected from each other by one of the exposed second thin film electrode layers and encompasses each of the patterned intermediate electrode layers, and each of the exposed second thin film electrode layers corresponds to the light reflecting portion in each of the thin film actuated mirrors;
• forming a first thin film electrode layer made of an electrically conducting and light reflecting material on top of the patterned structure to produce a semifinished actuated structure;
• patterning the semifinished actuated structure in a row direction, until the thin film sacrificial layer is exposed, into an array of M.times.N semifinished actuated mirrors, wherein each of the semifinished actuated mirrors includes a first thin film electrode, an upper electrodisplacive member, an intermediate electrode, a lower electrodisplacive member and a second thin film electrode;
• and
• removing the thin film sacrificial layer to thereby form an array of M.times.N thin film actuated mirrors.