Recovery of hydrophobicity of low-k and ultra low-k organosilicate films used as inter metal dielectrics

Abstract

Often used to reduce the RC delay in integrated circuits are dielectric films of porous organosilicates which have a silica like backbone with alkyl or aryl groups (to add hydrophobicity to the materials and create free volume) attached directly to the Si atoms in the network. Si—R bonds rarely survive an exposure to plasmas or chemical treatments commonly used in processing; this is especially the case in materials with an open cell pore structure. When Si—R bonds are broken, the materials lose hydrophobicity, due to formation of hydrophilic silanols and low dielectric constant is compromised. A method by which the hydrophobicity of the materials is recovered using a novel class of silylation agents which may have the general formula (R 2 N) X SiR′ Y where X and Y are integers from 1 to 3 and 3 to 1 respectively, and where R and R′ are selected from the group of hydrogen, alkyl, aryl, allyl and a vinyl moiety. Mechanical strength of porous organosilicates is also improved as a result of the silylation treatment.

1 . A method for restoring properties of an organosilicate film having hydrogen atoms or alkyl or aryl groups attached to silicon atoms, in a low or very low dielectric constant insulating layer in a semiconductor chip, chip carrier, or a semiconductor wafer wherein said organosilicate film has undergone processing tending to degrade its properties, the method comprising:
 applying to the film a silylating agent, so as to render the film hydrophobic, said silylating agent having the form R X H Y Si-A where X and Y are integers from 0 to 2 and 3 to 1, respectively and where R, is any hydrogen, alkyl, aryl, allyl, phenyl or vinyl moiety and where A is an amino, chloro or alkoxy moiety.   
     
     
         2 . A method as recited in  1 , wherein the processing includes etching of the film, and removing a photoresist material from the film, wherein the silylating agent is applied after the etching and the removing. 
     
     
         3 . A method as recited in  claim 2 , wherein the etching and removing are performed by exposing the film to a plasma. 
     
     
         4 . A method as recited in  claims 1  wherein a single damascene or a dual damascene processing is used, and said applying of said silylating agent is performed after definition of at least one of an interconnect line and a via, and prior to deposition of an electrical conductor. 
     
     
         5 . A method as recited in  claim 13 , wherein said applying of said silylating agent is performed prior to deposition of a conductive liner. 
     
     
         6 . A method for restoring properties of an organosilicate film having hydrogen atoms or alkyl or aryl groups attached to silicon atoms, in a low or very low dielectric constant insulating layer in a semiconductor chip, chip carrier, or a semiconductor wafer wherein said organosilicate film has undergone processing tending to degrade its properties, the method comprising:
 applying to the film a silylating agent, so as to render the film hydrophobic, said silylating agent comprising monofunctional terminating groups selected from amino, chloro or alkoxy groups and wherein methyl moieties on said silylating agent are at least partially replaced by hydrogen analogues.   
     
     
         7 . A method as recited in  6 , wherein the processing includes etching of the film, and removing a photoresist material from the film, wherein the silylating agent is applied after the etching and the removing. 
     
     
         8 . A method as recited in  claim 7 , wherein the etching and removing are performed by exposing the film to a plasma. 
     
     
         9 . A method as recited in  claims 6  wherein a single damascene or a dual damascene processing is used, and said applying of said silylating agent is performed after definition of at least one of an interconnect line and a via, and prior to deposition of an electrical conductor. 
     
     
         10 . A method for restoring properties of an organosilicate film having hydrogen atoms or alkyl or aryl groups attached to silicon atoms, in a low or very low dielectric constant insulating layer in a semiconductor chip, chip carrier, or a semiconductor wafer wherein said organosilicate film has undergone processing tending to degrade its properties, the method comprising:
 applying to the film a silylating agent, so as to render the film hydrophobic, said silylating agent comprising a polymeric siloxane with amino, alkoxy, chloro or silazane terminated end groups.   
     
     
         11 . A method as recited in  claim 10 , wherein said end groups of the polymeric siloxanes comprise mono or di alkyl, aryl, vinyl or hydrogen moieties. 
     
     
         12 . A method as recited in  claim 10 , wherein said siloxane comprises amino terminated polydimethylsiloxane. 
     
     
         13 . A method as recited in  claim 10 , wherein the processing includes etching of the film, and removing a photoresist material from the film, wherein the silylating agent is applied after the etching and the removing. 
     
     
         14 . A method as recited in  claim 13 , wherein the etching and removing are performed by exposing the film to a plasma. 
     
     
         15 . A method as recited in  claim 10 , wherein a single damascene or a dual damascene processing is used, and said applying of said silylating agent is performed after definition of at least one of an interconnect line and a via, and prior to deposition of an electrical conductor. 
     
     
         16 . A method for restoring properties of an organosilicate film having hydrogen atoms or alkyl or aryl groups attached to silicon atoms, in a low or very low dielectric constant insulating layer in a semiconductor chip, chip carrier, or a semiconductor wafer wherein said organosilicate film has undergone processing tending to degrade its properties, the method comprising:
 applying to the film a silylating agent, so as to render the film hydrophobic, the silylating agent having the general formula R X H Y Si Z A where X, and Y, and Z are integers from 0 to 5, and 6 to 1 and Z is equal to 2, respectively and where R is a hydrogen, alkyl, aryl, allyl, phenyl or vinyl moiety, and A is a silazane.   
     
     
         17 . A method as recited in  16 , wherein the processing includes etching of the film, and removing a photoresist material from the film, wherein the silylating agent is applied after the etching and the removing. 
     
     
         18 . A method as recited in  claim 17 , wherein the etching and removing are performed by exposing the film to a plasma. 
     
     
         19 . A method as recited in  claim 16 , wherein a single damascene or a dual damascene processing is used, and said applying of said silylating agent is performed after definition of at least one of an interconnect line and a via, and prior to deposition of an electrical conductor. 
     
     
         20 . A method as recited in  claim 13 , wherein said applying of said silylating agent is performed prior to deposition of a conductive liner.