Polishing inhibiting layer forming additive

Abstract

A polishing inhibiting layer forming additive for a slurry, the slurry so formed, and a method of chemical mechanical polishing are disclosed. The polishing inhibiting layer is formed through application of the slurry to the surface being polished and is removable at a critical polishing pressure. The polishing inhibiting layer allows recessed or low pattern density locations to be protected until a critical polishing pressure is exceeded based on geometric and planarity considerations, rather than slurry or polishing pad considerations. With the additive, polishing rate is non-linear relative to polishing pressure in a recessed/less pattern dense location. In one embodiment, the additive has a chemical structure: [CH 3 (CH 2 ) x N(R)]M, wherein M is selected from the group consisting of: Cl, Br and I, x equals an integer between 2 and 24, and the R includes three carbon-based functional groups, each having less than eight carbon atoms.

1 .- 5 . (canceled) 
     
     
         6 . A wafer polishing system, comprising:
 a semiconductor wafer having a topography including a first topography location and a different second topography location;   a slurry including a plurality of polishing particles and an additive for forming a polishing inhibiting layer in situ across the topography, wherein the additive and a surface of the topography have opposite electrostatic charges to ensure adhesion of the polishing inhibiting layer to the surface of the topography, the polishing inhibiting layer forming additive providing a polishing rate for the topography that is non-linear with polishing pressure when polishing the topography, the additive includes one of: an anionic surfactant and a cationic surfactant and wherein the cationic surfactant includes a chemical structure selected from the group consisting of:   a) [CH 3 (CH 2 ) x N(R)]M, wherein M is selected from the group consisting of: Cl, Br and I, x equals an integer between 2 and 24, and the R includes three carbon-based functional groups, each having less than eight carbon atoms; and   b) C p H q QN, where Q is selected from the group consisting of: Cl, Br and I, and p>8 and q>20.   
     
     
         7 . The system of  claim 6  wherein the anionic surfactant includes at least one of: sodium sulfate, sodium dodecyl sulfate, sodium lauryl sulfate, sodium stearate and sodium tetradecyl sulfate. 
     
     
         8 . The system of  claim 6 , wherein the carbon-based functional groups are selected from the group consisting of: CH 3 , CH 2 OH, C 2 H 4 OH, C 2 H 5 , C 3 H 6 OH and C 3 H 7 . 
     
     
         9 . The system of  claim 6 , wherein the cationic surfactant includes C p H q QN, and Q is Cl, p=21, and q=38, resulting in cetylpyridinium chloride (C 21 H 38 ClN). 
     
     
         10 . The system of  claim 6 , wherein the anionic surfactant includes at least one of: sodium sulfate, sodium dodecyl sulfate, sodium lauryl sulfate, sodium stearate and sodium tetradecyl sulfate. 
     
     
         11 . The system of  claim 6 , wherein the polishing inhibiting layer is removable from the surface at a critical removal polishing pressure P crit  that is no less than approximately 2 psi and no greater than approximately 20 psi. 
     
     
         12 . The system of  claim 6 , wherein the slurry has a pH level between an isoelectric point of the surface and an isoelectric point of the plurality of polishing particles to cause adhesion of the layer to the surface.