Methods of forming fusible devices

Abstract

The present invention relates to a laser fuse. The laser fuse comprises an element comprising a heat conductive material. The fuse also includes an absorption element comprising a material with an adjustable capacity for heat or light absorption that overlays the heat conductive element. The fuse also includes an outer insulating element that overlays and encloses the heat conductive element and the absorption element.

1 . A method for forming one or more circuits, comprising: 
 providing a substrate comprising polycrystalline silicon;    oxidizing at least a portion of the polycrystalline silicon to form silicon dioxide;    patterning the silicon dioxide to define at least one source, drain and gate region between the source and the drain;    depositing a conductive layer over at least a portion of the polycrystalline silicon and silicon dioxide and patterning the conductive layer to make at least one circuit comprising a source, drain, and gate of preselected design;    fabricating one or more fuses by overlaying the silicon dioxide with an absorption element with a silicon to nitride ratio effective for absorbing laser energy within a first narrow wavelength range, and overlaying the silicon dioxide with an absorption element with a silicon to nitride ratio effective for absorbing laser energy within a second narrow wavelength range different from the first wavelength range, and patterning the first stack and second stack to form two fuse stacks; and    and linking the two fuse stacks to the circuit of preselected design.    
   
   
       2 . The method of  claim 1 , wherein linking is performed by patterning the conductive layer to form a fusible link that links the fuses to the circuit.  
   
   
       3 . The method of  claim 1 , wherein linking is performed by fabricating a fusible link with the one or more laser fuses that links the fuses to the circuit.  
   
   
       4 . The method of  claim 1 , further comprising fabricating the one or more fuses so that the gate is positioned between two fuses.  
   
   
       5 . The method of  claim 1 , further comprising overlaying the absorption element with a dielectric film.  
   
   
       6 . The method of  claim 5 , wherein the dielectric film is overlayed onto the absorption element by chemical vapor deposition.  
   
   
       7 . The method of  claim 5 , wherein the dielectric film is overlayed onto the absorption element by plasma enhanced chemical vapor deposition.  
   
   
       8 . The method of  claim 1 , further comprising linking the fuse stack to another circuit.  
   
   
       9 . A method for forming one or more circuits, comprising: 
 providing a substrate comprising polycrystalline silicon;    oxidizing at least a portion of the polycrystalline silicon to form silicon dioxide;    patterning the silicon dioxide to define a source, a drain and a gate region between the source and the drain;    depositing a conductive layer over at least a portion of the polycrystalline silicon and silicon dioxide and patterning the conductive layer to make a circuit comprising a source, drain, and gate of preselected design;    fabricating one or more fuse by overlaying the conductive layer with an absorption element with a silicon to nitride ratio effective for absorbing laser energy within a first narrow wavelength range, and overlaying the conductive layer with an absorption element with a silicon to nitride ratio effective for absorbing laser energy within a second narrow wavelength range different from the first wavelength range, and patterning the first stack and second stack to form two fuse stacks; and    and linking the two fuse stacks to the circuit of preselected design.    
   
   
       10 . The method of  claim 9 , wherein linking is performed by patterning the conductive layer to form a fusible link.  
   
   
       11 . The method of  claim 9 , wherein linking is performed by fabricating a link with the one or more laser fuses.  
   
   
       12 . The method of  claim 9 , further including adjusting the silicon-to-nitride stoichiometric ratio of 3-to-4 for the absorption element.  
   
   
       13 . A method for forming a circuit, comprising: 
 providing a semiconductive substrate;    forming isolation regions and thin oxide body regions in the semiconductive substrate;    depositing a polycrystalline silicon layer on the semiconductive substrate;    patterning the polycrystalline silicon layer;    forming diffusion regions in portions of the thin oxide body regions;    oxidizing at least a portion of the polycrystalline silicon to form silicon dioxide;    depositing a dielectric layer on the polycrystalline silicon and silicon dioxide;    patterning the dielectric layer and the silicon dioxide to define contact points for at least a source, a drain and a gate region disposed between the source and the drain;    depositing a conductive layer over at least a portion of the polycrystalline silicon and silicon dioxide and patterning the conductive layer to form a circuit comprising at least one source, drain, and gate;    forming at least one fuse by overlaying the conductive layer with an absorption element having a silicon to nitride ratio effective for absorbing laser energy within a first narrow wavelength range; and    and linking the at least one fuse to the circuit.    
   
   
       14 . The method of  claim 13 , further including overlaying the conductive layer with a second absorption element with a silicon to nitride ratio effective for absorbing laser energy within a second narrow wavelength range.  
   
   
       15 . The method of  claim 14 , wherein the second narrow wavelength range is different from the first narrow wavelength range.  
   
   
       16 . The method of  claim 15 , further including patterning the first fuse and second fuse to form two fuses connected so that the gate is positioned between the fuses.  
   
   
       17 . The method of  claim 13 , further including forming a heat conductive layer over the polycrystalline silicon layer.  
   
   
       18 . The method of  claim 17 , further including patterning the heat conductive layer before patterning the polycrystalline silicon layer.  
   
   
       19 . The method of  claim 17 , further including forming a deposited radiation absorbing layer over the heat conductive layer.  
   
   
       20 . The method of  claim 19 , further including forming an insulating protective layer over the deposited radiation absorbing layer.  
   
   
       21 . The method of  claim 19 , further including patterning the deposited radiation absorbing layer before patterning the heat conductive layer.  
   
   
       22 . The method of  claim 13 , wherein patterning the polycrystalline silicon layer includes patterning a narrower region connected between two wider polycrystalline silicon regions to form a fusible link region more sensitive to radiation.  
   
   
       23 . The method of  claim 22 , where the radiation includes laser radiation at a selected wavelength.  
   
   
       24 . The method of  claim 23 , wherein the selected wavelength of laser radiation ranges between 1037 to 1057 nanometers.  
   
   
       25 . The method of  claim 24 , wherein the absorption element comprises a silicon rich silicon nitride material.  
   
   
       26 . The method of  claim 25 , wherein the silicon rich silicon nitride material comprises a material having a silicon to nitrogen atomic ration of greater than 3 to 4.