Semiconductor wafer including a low dielectric constant thermosetting polymer film and method of making same

Abstract

A semiconductor wafer provided with a thermosetting porous insulating film, wherein the insulating film is made porous, cured and polymerized on the wafer. The film is characterized by a very low dielectric constant based on its constituency and porosity, the latter property of which is caused by the inclusion of liquid or supercritical carbon dioxide in the polymeric reaction mixture.

1 . A semiconductor wafer comprising a film layer, said film layer provided by disposing a composition comprising at least one curable monomer, a solvent therefor and liquid or supercritical carbon dioxide on a semiconductor wafer, said composition disposed on said wafer at a temperature in the range of between about 30° C. and about 50° C. and a pressure of at least about 73 atmospheres; incrementally raising said temperature to a temperature of about 450° C.; and thereafter incrementally reducing said temperature to ambient; said pressure not decreasing during said incremental temperature increase until said temperature reaches about 400° C., at which point said pressure is incrementally reduced to atmosphere.  
     
     
         2 . A wafer in accordance with  claim 1  wherein said temperature and said pressure of said initial contact between said curable monomer and said liquid or supercritical carbon dioxide is in the range of between about 35° C. and about 40° C. and between about 75 atmospheres and about 90 atmospheres.  
     
     
         3 . A wafer in accordance with  claim 1  wherein said temperature is increased at a rate in the range of between about 15° C. per minute and about 40° C. per minute up to a temperature of about 200° C.  
     
     
         4 . A wafer in accordance with  claim 3  wherein said temperature is maintained fixed, for a duration of between about 30 seconds and about 120 seconds, when said temperature is raised to about 100° C. and about 200° C.  
     
     
         5 . A wafer in accordance with  claim 3  wherein said temperature is raised at a raising rate in the range of between about 10° C. per minute and about 35° C. per minute when said temperature is raised from about 200° C. to about 400° C.  
     
     
         6 . A wafer in accordance with  claim 5  wherein said temperature is maintained fixed, for a duration of between about 30 seconds and about 120 seconds, when said temperature is raised to about 310° C. and about 400° C.  
     
     
         7 . A wafer in accordance with  claim 5  wherein said temperature rise from about 400° to about 450° C. occurs at an increasing rate in the range of between about 3° C. per minute and about 10° C. per minute.  
     
     
         8 . A wafer in accordance with  claim 1  wherein said pressure is reduced at a rate of between about 0.1 atmosphere to about 2 atmospheres per second, when said temperature reaches a temperature of at least about 310° C.  
     
     
         9 . A wafer in accordance with  claim 1  wherein said temperature is reduced, at a rate in the range of between about 10° C. per minute and about 25° C. per minute, when said reaches about 450° C. until ambient temperature is reached.  
     
     
         10 . A wafer in accordance with  claim 1  wherein said composition comprises said at least one curable monomer, a solvent therefor, liquid or supercritical carbon dioxide and, optionally, a co-solvent.  
     
     
         11 . A wafer in accordance with  claim 10  wherein said at least one curable monomer is present in a concentration of between about 5% and about 25%; said solvent is present in a concentration of between about 30% and about 40%; said liquid or supercritical carbon dioxide is present in a concentration of between about 25% and about 65%; and said co-solvent is present in a concentration of between 0 and about 20%, said percentages being by weight, based on the total weight of the composition.  
     
     
         12 . A wafer in accordance with  claim 11  wherein said composition includes said co-solvent and said composition comprises between about 5% and about 15% monomer, between about 35% and about 40% solvent, between about 40% and about 53% liquid or supercritical carbon dioxide and between about 2% and about 10% co-solvent.  
     
     
         13 . A wafer in accordance with  claim 10  wherein said solvent is a polar solvent selected from the group consisting of lactones, ketones and aldehydes or an apolar hydrocarbon solvent.  
     
     
         14 . A wafer in accordance with  claim 13  wherein said solvent is selected from the group consisting of δ-butyrolactone, cyclohexanone and butanal.  
     
     
         15 . A wafer in accordance with  claim 10  wherein said optional co-solvent is an alcohol having the structural formula ROH, where R is C 4 -C 10  alkyl or C 5 -C 7  cycloalkyl.  
     
     
         16 . A wafer in accordance with  claim 1  wherein said at least one curable monomer is selected from the group consisting of unsaturated aryl ethers, arylenes, phenylethynyls, organosiloxanes, imides, organosilazanes, hydroxyarylenes and paralenes.  
     
     
         17 . A wafer in accordance with  claim 16  wherein said curable monomer is a phenylethynyl or an imide.  
     
     
         18 - 20 . Cancelled.