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 a fuse, comprising: 
 forming an oxide layer on a semiconductor substrate;    forming a polycrystalline silicon layer on the oxide layer;    patterning the polycrystalline silicon layer;    forming a heat conductive layer over the polycrystalline silicon layer;    patterning the heat conductive layer;    forming a deposited radiation absorbing layer over the heat conductive layer; and    forming an insulating protective layer over the deposited radiation absorbing layer.    
   
   
       2 . The method of forming a fuse of  claim 1 , wherein the radiation absorbing layer is engineered to absorb laser radiation at a selected wavelength range.  
   
   
       3 . The method of forming a fuse of  claim 2 , wherein the selected laser wavelength range for absorption is between 1037 to 1057 nanometers.  
   
   
       4 . The method of forming a fuse of  claim 1 , wherein the deposited radiation absorbing layer comprises a silicon rich silicon nitride material.  
   
   
       5 . The method of forming a fuse of  claim 4 , wherein the silicon rich silicon nitride material comprises a material having a silicon to nitrogen atomic ratio of greater than 3.  
   
   
       6 . The method of forming a fuse of  claim 4 , wherein the silicon rich silicon nitride material comprises a material having a silicon to nitrogen atomic ratio of greater than 4.  
   
   
       7 . The method of forming a fuse of  claim 1 , wherein the polycrystalline silicon pattern includes a narrower region connected between wider polycrystalline silicon regions to form a fusible link.  
   
   
       8 . The method of forming a fuse of  claim 1 , wherein the polycrystalline silicon layer is doped before patterning.  
   
   
       9 . The method of forming a fuse of  claim 1 , wherein the heat conductive layer is formed of at least one of tungsten, a refractory metal and a refractory metal silicide.  
   
   
       10 . The method of forming a fuse of  claim 1 , wherein the polycrystalline silicon layer and the heat conductive layer patterns are performed in the same patterning step.  
   
   
       11 . The method of forming a fuse of  claim 1 , wherein the patterning of the heat conductive layer has substantially the same pattern as the patterned polycrystalline silicon layer.  
   
   
       12 . The method of forming a fuse of  claim 1 , wherein the insulating layer is formed with a thickness that transmits greater than 50% of incident laser radiation at a wavelength of between 1037 to 1057 nanometers.  
   
   
       13 . A method for forming fuses, comprising: 
 providing a substrate comprising polycrystalline silicon and patterning the polycrystalline silicon;    oxidizing at least a portion of the polycrystalline silicon to form silicon dioxide;    depositing a conductive layer over at least a portion of the polycrystalline silicon and silicon dioxide and patterning the conductive layer;    fabricating at least a first fuse by overlaying a first portion of the silicon dioxide with a first absorption element with a silicon to nitride ratio effective for absorbing laser energy within a first narrow wavelength range; and    fabricating at least a second fuse by overlaying a second portion of the silicon dioxide with a second absorption element with a silicon to nitride ratio effective for absorbing laser energy within a second narrow wavelength range.    
   
   
       14 . The method of  claim 13 , wherein the second wavelength is different from the first wavelength range.  
   
   
       15 . The method of  claim 13 , further including patterning at least one of the polycrystalline silicon, the silicon dioxide and the conductive layer to form at least a first fuse stack and at least a second fuse stack.  
   
   
       16 . The method of  claim 15 , wherein a linking is performed by patterning the conductive layer to form a fusible link that links at least the first and second fuses to a circuit.  
   
   
       17 . The method of  claim 15 , wherein the polycrystalline silicon pattern includes a narrower region connected between wider polycrystalline silicon regions to form a fusible link.  
   
   
       18 . The method of  claim 13 , further comprising overlaying the first and second absorption elements with a dielectric film.  
   
   
       19 . The method of  claim 18 , wherein the dielectric film has a different dielectric constant from the first and second absorption elements.  
   
   
       20 . The method of  claim 19 , wherein the dielectric film is deposited by one of chemical vapor deposition, plasma enhanced chemical vapor deposition, physical deposition, evaporation and sputtering.  
   
   
       21 . The method of  claim 15 , wherein a bottom anti-reflection coating is deposited on at least one of the polycrystalline silicon, the silicon dioxide and the conductive layer prior to a photo resist deposition in the patterning step.  
   
   
       22 . The method of  claim 21 , wherein the bottom anti-reflection coating remains on the at least one of the polycrystalline silicon, the silicon dioxide and the conductive layer after the completion of the patterning step.  
   
   
       23 . The method of  claim 13 , wherein the first absorption element comprises a silicon to nitride ratio above 3-to-4, and the second absorption element comprises a silicon to nitride ratio below 3-to-4.