Micromachine and manufacturing method therefor

Abstract

In a micromachine according to this invention, a polyimide film is formed on the surface of each electrode. The polyimide film is formed as follows. A substrate having each electrode and a counterelectrode are dipped in an electrodeposition polyimide solution, and a positive voltage is applied to the electrode. A material dissolved in the electrodeposition polyimide solution is deposited on a surface of the positive-voltage-applied electrode that is exposed in the solution, thus forming a polyimide film on the surface.

What is claimed is:  
     
         1 . A micromachine comprising: 
 a control electrode formed on a substrate;    a movable portion which is arranged above said control electrode at a predetermined distance; and    a polyimide film which is formed from polyimide and covers at least one of a surface of said control electrode and a surface of said movable portion,    wherein said movable portion is operated by applying an electrical signal to said control electrode.    
     
     
         2 . A micromachine according to  claim 1 , wherein said movable portion includes an extending portion of a driving electrode which is formed on the substrate and insulated from said control electrode.  
     
     
         3 . A micromachine according to  claim 1 , wherein said movable portion includes a mirror which is pivotally coupled via a coupling portion to a mirror substrate supported by a column formed on the substrate.  
     
     
         4 . A micromachine according to  claim 1 , wherein 
 said movable portion is formed from polysilicon, and    said control electrode is formed from gold and chromium.    
     
     
         5 . A micromachine according to  claim 1 , wherein said control electrode and said movable portion are formed from polysilicon.  
     
     
         6 . A micromachine according to  claim 1 , wherein said control electrode and said movable portion are formed from gold and chromium.  
     
     
         7 . A micromachine according to  claim 1 , wherein said polyimide film is formed by electrodeposition.  
     
     
         8 . A micromachine according to  claim 3 , wherein 
 the substrate includes a semiconductor substrate,    the column is formed on the semiconductor substrate via an interlayer dielectric film and is conductive,    the mirror is conductive, and    a control circuit having a plurality of elements is arranged on the semiconductor substrate below the interlayer dielectric film.    
     
     
         9 . A micromachine manufacturing method comprising: 
 the first step of forming a control electrode on a substrate;    the second step of forming on the substrate a driving electrode which is insulated from the control electrode and has a portion extending above the control electrode; and    the third step of dipping the control electrode and the driving electrode in an electrodeposition polyimide solution, and applying a positive voltage to at least one of the control electrode and the driving electrode to form a polyimide film by electrodeposition on at least one of a surface of the control electrode and a surface of the driving electrode.    
     
     
         10 . A micromachine manufacturing method comprising the steps of: 
 forming a control circuit from a plurality of elements on a semiconductor substrate;    forming an interlayer dielectric film on the semiconductor substrate to cover the control circuit;    forming a seed layer on the interlayer dielectric film;    forming a first sacrificial pattern having a first opening region and a plurality of second opening regions on the seed layer;    forming first and second metal patterns having substantially the same film thickness as a film thickness of the first sacrificial pattern by plating on the seed layer exposed in the first and second regions;    forming a second sacrificial pattern having a third opening region above the first region on the first sacrificial pattern and the second metal pattern;    forming a third metal pattern having substantially the same film thickness as a film thickness of the second sacrificial pattern by plating on a surface of the first metal pattern exposed in the third region;    after forming the third metal pattern, removing the first and second sacrificial patterns;    after removing the first and second sacrificial patterns, dipping in an electrodeposition polyimide solution a plurality of control electrodes which are formed from a plurality of second metal patterns and separated on the interlayer dielectric film, and applying a positive voltage to the control electrodes to form polyimide films on surfaces of the control electrodes by electrodeposition;    after forming the polyimide films, selectively removing the seed layer by using the first and second metal patterns as a mask, thereby forming a column from a multilayered structure of the first and third metal patterns together with the control electrodes;    preparing a conductive mirror substrate on which mirrors are arranged in a plurality of opening regions and pivotally coupled via coupling portions; and    connecting and fixing the mirror substrate on the column so as to arrange the plurality of mirrors above the plurality of control electrodes at an interval in correspondence with each other,    wherein the control electrodes are so connected as to allow applying a predetermined signal by the control circuit.    
     
     
         11 . A method according to  claim 10 , wherein 
 the seed layer is formed from a gold upper seed layer and a titanium lower seed layer,    the first to third metal patterns are formed by plating gold,    a titanium metal film is formed on the third metal pattern before the first and second sacrificial patterns are removed,    the first and second sacrificial patterns are removed after the metal film is formed,    the upper seed layer exposed between the first and second metal patterns after removal of the first and second sacrificial patterns is selectively removed using the first and second metal patterns as a mask, thereby exposing part of the lower seed layer,    polyimide is electrodeposited after an oxide film is formed on the exposed lower seed layer and a surface of the metal film,    the oxide film is removed by removing the lower seed layer and the metal film after the polyimide film is formed, and    the mirror substrate is connected and fixed to the column after the oxide film is removed.    
     
     
         12 . A micromachine manufacturing method comprising the steps of: 
 forming on a substrate a plurality of chip regions which are separated by a cutting region;    forming a common interconnection in the cutting region;    forming control electrodes on the substrate for the respective chip regions;    forming, on the substrate for the respective chip regions, driving electrodes which are insulated from the control electrodes, have portions extending above the control electrodes, and are connected to the common interconnection; and    dipping the control electrodes and the driving electrodes in an electrodeposition polyimide solution, and applying a voltage to the common interconnection to form a polyimide film by electrodeposition on either or both of a surface of each driving electrode and a surface of each control electrode.    
     
     
         13 . A micromachine manufacturing method comprising the steps of: 
 forming on a semiconductor substrate a plurality of chip regions which are separated by a cutting region;    forming a common interconnection in the cutting region;    forming on the semiconductor substrate for each chip region a control circuit from a plurality of elements and an interconnection layer connected to the common interconnection;    forming an interlayer dielectric film on the semiconductor substrate to cover the control circuit and the interconnection layer;    forming on the interlayer dielectric film a seed layer which is partially connected to the interconnection layer;    forming a first sacrificial pattern having a first opening region and a plurality of second opening regions on the seed layer;    forming first and second metal patterns having substantially the same film thickness as a film thickness of the first sacrificial pattern by plating on the seed layer exposed in the first and second regions;    forming a second sacrificial pattern having a third opening region above the first region on the first sacrificial pattern and the second metal pattern;    forming a third metal pattern having substantially the same film thickness as a film thickness of the second sacrificial pattern by plating on a surface of the first metal pattern exposed in the third region;    after forming the third metal pattern, removing the first and second sacrificial patterns;    after removing the first and second sacrificial patterns, dipping in an electrodeposition polyimide solution a plurality of control electrodes which are formed from a plurality of second metal patterns and separated on the interlayer dielectric film, and applying a voltage to the interconnection layer to form polyimide films on surfaces of the control electrodes by electrodeposition;    after forming the polyimide films, selectively removing the seed layer by using the first and second metal patterns as a mask, thereby forming a support member from a multilayered structure of the first and third metal patterns together with the control electrodes;    preparing a conductive mirror semiconductor substrate on which mirrors are arranged in a plurality of opening regions and pivotally coupled via coupling portions; and    connecting and fixing the mirror semiconductor substrate on the support member so as to arrange the plurality of mirrors above the plurality of control electrodes at an interval in correspondence with each other,    wherein the control electrodes are so connected as to allow applying a predetermined signal by the control circuit.    
     
     
         14 . A method according to  claim 13 , wherein 
 the seed layer is formed from a gold upper seed layer and a titanium lower seed layer,    the first to third metal patterns are formed by plating gold,    a titanium metal film is formed on the third metal pattern before the first and second sacrificial patterns are removed,    the first and second sacrificial patterns are removed after the metal film is formed,    the upper seed layer exposed between the first and second metal patterns after removal of the first and second sacrificial patterns is selectively removed using the first and second metal patterns as a mask, thereby exposing part of the lower seed layer,    polyimide is electrodeposited after an oxide film is formed on the exposed lower seed layer and a surface of the metal film,    the oxide film is removed by removing the lower seed layer and the metal film after the polyimide film is formed, and    the mirror semiconductor substrate is connected and fixed to the support member after the oxide film is removed.    
     
     
         15 . A method according to  claim 12 , further comprising the step of removing the cutting region together with the common interconnection, thereby cutting the substrate into the plurality of chip regions.  
     
     
         16 . A method according to  claim 13 , further comprising the step of removing the cutting region together with the common interconnection, thereby cutting the semiconductor substrate into the plurality of chip regions.