Method for Pore Sealing of Porous Materials Using Polyimide Langmuir-Blodgett Film

Abstract

Method for pore sealing a porous substrate, comprising: forming a continuous monolayer of a polyimide precursor on a liquid surface, transferring said polyimide precursor monolayer onto the porous substrate with the Langmuir-Blodgett technique, and imidization of the transferred polyimide precursor monolayers, thereby forming a polyimide sealing layer on the porous substrate. Porous substrate having at least one surface on which a sealing layer is provided to seal pores of the substrate, wherein the sealing layer is a polyimide having a thickness of a few monolayers and wherein there is no penetration of the polyimide into the pores.

1 . A porous substrate having at least one surface on which a sealing layer is provided to seal pores of the porous substrate,
 wherein the porous substrate is an ultra-low κ dielectric material having a dielectric constant κ lower than 2.3 and the porous substrate has a pore size of 1 to 5 nm, and   wherein the sealing layer comprises a continuous monolayer of a polyimide precursor.   
     
     
         2 . The porous substrate of  claim 1 , wherein the sealing layer has a thickness lower than 5 nm. 
     
     
         3 . The porous substrate of  claim 1 , wherein the polyimide precursor is polyamic acid alkylamine salt. 
     
     
         4 . The porous substrate of  claim 1 , wherein the sealing layer does not penetrate into pores of the porous substrate. 
     
     
         5 . The porous substrate of  claim 1 , wherein the dielectric constant κ is lower than 2.1. 
     
     
         6 . The porous substrate of  claim 1 , wherein the porous substrate has an average pore size of 2 nm. 
     
     
         7 . The porous substrate of  claim 1 , wherein the substrate is a porous organosilicate. 
     
     
         8 . The porous substrate of  claim 7 , wherein the porous organosilicate comprises SiOCH material having a κ-value of 2.3 and an average pore size of 2 nm. 
     
     
         9 . The porous substrate of  claim 1 , wherein the sealing layer has a dielectric constant of 3.3 or less. 
     
     
         10 . The porous substrate of  claim 1 , wherein a combination of the porous substrate and the sealing layer has a refractive index of between 1.33 and 1.36 as obtained by ellipsometric porosimetry. 
     
     
         11 . The porous substrate of  claim 1 , wherein the continuous monolayer of a polyimide precursor is compatible with a Langmuir-Blodgett deposition technique. 
     
     
         12 . An integrated circuit comprising:
 a substrate, wherein the substrate is an ultra-low κ dielectric material having a dielectric constant κ lower than 2.3, wherein a surface of the substrate comprises a plurality of pores with pore sizes between 1 and 5 nm; and   a sealing layer directly overlaying the surface of the substrate and sealing at least a portion of the pores of the surface such that the sealing layer does not penetrate into the pores, wherein the sealing layer comprises a continuous monolayer of polyimide.   
     
     
         13 . The integrated circuit of  claim 12 , wherein the sealing layer has a thickness lower than 5nm. 
     
     
         14 . The integrated circuit of  claim 12 , wherein a dielectric constant κ of the substrate is lower than 2.1. 
     
     
         15 . The integrated circuit of  claim 12 , wherein the substrate has an average pore size of 2 nm. 
     
     
         16 . The integrated circuit of  claim 12 , wherein the substrate is a porous organosilicate. 
     
     
         17 . The integrated circuit of  claim 16 , wherein the porous organosilicate comprises SiOCH material having a dielectric constant κ of 2.3 and an average pore size of 2 nm. 
     
     
         18 . The integrated circuit of  claim 12 , wherein the sealing layer has a dielectric constant of 3.3 or less. 
     
     
         19 . The integrated circuit of  claim 12 , wherein a combination of the substrate and the sealing layer has a refractive index of between 1.33 and 1.36 as obtained by ellipsometric porosimetry. 
     
     
         20 . The integrated circuit of  claim 12 , wherein the continuous monolayer of polyimide is compatible with a Langmuir-Blodgett deposition technique.