Freestanding multilayer IC wiring structure

Abstract

A dielectric wiring structure and method of manufacture therefor. The wiring structure includes air dielectric formed in a hemisphere. The wiring structure also includes, in embodiments, a method of simultaneously forming a MEMS structure with a transistor circuit using substantially the same steps. The MEMS structure of this embodiment includes freestanding electrodes which are not fixed to the substrate.

1 - 18 . (canceled)  
   
   
       19 . A method of forming a wiring structure comprising the steps of: 
 forming a removable dielectric structure with wiring contained within the removable dielectric structure, the wiring including wire levels; and    etching multiple regions of the removable dielectric structure to form air gaps,    wherein the wiring extends from within the etched region to an adjacent non-etched perimeter region.    
   
   
       20 . The method of  claim 19 , comprising refilling the multiple etched regions with a removable dielectric layer.  
   
   
       21 . The method of  claim 20 , further comprising capping the etched multiple regions with a capping layer after the refilling step.  
   
   
       22 . The method of  claim 21 , further comprising: 
 forming a vent hole in the capping layer;    removing the removable dielectric layer; and    plugging the vent hole.    
   
   
       23 . The method of  claim 19 , further comprising the steps of: 
 forming a permanent structure in contact with and supporting the wiring while forming the removable dielectric structure; and    etching the permanent structure exposed within the multiple etched regions,    wherein the step of etching the permanent structure first includes etching the multiple etched regions, and the wiring and the permanent structure are contained within the removable dielectric structure.    
   
   
       24 . The method of  claim 23 , wherein: 
 the permanent structure is a horizontal layer in contact with the wiring contained within the removable dielectric structure; and    the horizontal layer is at least two horizontal layers;    the etching step is an isotropic etch which etches the removable structure and further etches through at least one of the horizontal layers thereby forming the multiple etched regions, the multiple etched regions are sections of multiple hemispheres.    
   
   
       25 . The method of  claim 19 , further comprising: 
 refilling the multiple etched regions with a removable dielectric layer;    forming a permanent layer on a surface of the non-etched perimeter region prior to the refilling step; and    capping the etched multiple regions after the refilling step,    wherein the multiple etched regions are formed by isotropic etching through a capping layer formed by the capping step which is substantially removed.    
   
   
       26 . The method of  claim 25 , further comprising venting the permanent structure to provide access to removable material of the removable dielectric structure residing within the non-etched perimeter region.  
   
   
       27 . The method of  claim 19 , further comprising forming a capping layer prior to the etching of the multiple regions.  
   
   
       28 . The method of  claim 27 , wherein the multiple etched regions are defined by forming vents in the capping layer and isotropically etching the underlying removable dielectric structure.  
   
   
       29 . The method of  claim 19 , further comprising: 
 forming a permanent structure for at least one of the wire levels of the wiring by etching a wire trench and a via trench in the removable dielectric structure, wherein the permanent structure includes:    depositing a metal liner in the wire trench;    electroplating copper on the metal liner; and    polishing the metal liner and the copper from a surface of the removable dielectric structure, and    depositing a layer of dielectric on the metal liner which is to form a permanent layer.    
   
   
       30 . A method of forming a wiring structure comprising the steps of: 
 forming at least a transistor on a substrate in a first region;    forming a multilayered stack wiring level containing at least one conductor and removable material layer in a second region adjacent to the first region;    patterning the at least one conductor to form an electrode of a micro-electromechanical (MEMS) device;    simultaneously forming removable interlevel dielectric overlying the transistors of the first region and surrounding the multilayer stack of the second region which connect to the transistors;    forming wires which interconnect with the MEMS device;    forming air dielectric by removing the removable interlevel dielectric simultaneously overlying the transistors in the first region and the second region; and    removing the removable material to form a moveable electrode.    
   
   
       31 . The method of  claim 30 , further comprising: 
 simultaneously forming a permanent dielectric within the second region overlying the transistors of the first region, wherein    the permanent dielectric being resistant to attack by a method used to remove the removable dielectric,    the permanent dielectric interconnects and supports the wiring, and    the permanent dielectric connects to and supports the at least the conductor of the multilayer stack wiring level.    
   
   
       32 . The method of  claim 30 , wherein the wiring is formed by: 
 forming trenches in the removable dielectric; depositing a conductive layer on walls of the trenches;    electroplating copper on the surface of the conductive layer; and    polishing the copper from a top surface of the removable dielectric to leave a copper line within the trenches.    
   
   
       33 . The method of  claim 32 , wherein: 
 the multilayered stack wiring layer is at least two multilayered stack wiring layer,    one of the at least two multilayered stack wiring layers has a top conductor layer,    the method including the further steps of: 
 forming trenches in the removable dielectric, wherein at least a first set of trenches in the second region being formed over an edge of the multilayered stack wiring layer;  
 depositing a contact in at least a second set of trenches contacting a top conductor layer of one of the multilayered stack wiring layers; and  
 forming vents in the first region and the second region.  
   
   
   
       34 . A method of forming a micro electromechanical structure with two moveable elements comprising the steps of: 
 forming a first layer which includes a first area of at least one material which will become a first moveable element;    depositing a removable dielectric to form a first removable spacer;    forming a second layer which includes a second area of at least one material which will become a second moveable element onto the removable spacer, the second area overlying the first area;    forming and patterning a material which overlies the first area and the second area, wherein the patterned material is a mask for etching;    etching a first edge of the first area and a second edge of the second area where the second edge directly overlies said first edge;    depositing a resistant material which is resistant to a method used to remove the removable spacer to form a layer which connects the first edge to the second edge; and    removing the removable dielectric.    
   
   
       35 . The method of  claim 34 , further comprising depositing a layer of removable dielectric prior to the forming and patterning step in order to form a second removable spacer overlying the second area.  
   
   
       36 . The method of  claim 35 , further comprising forming a supporting region which supports the micro electromechanical structure, the supporting region being resistant to removal during removal of the removable material, prior to the depositing of the of the resistant material, wherein the resistant material connects the first edge to the second edge to the supporting region.