Germanium chemical mechanical polishing

Abstract

A method of planarizing/polishing germanium is described. The method comprises the step of abrading the surface of a substrate comprising germanium with an aqueous chemical mechanical polishing (CMP) composition comprising an oxidizing agent, a particulate abrasive, and a germanium etching inhibitor. The germanium etching inhibit is selected from the group consisting of a water-soluble polymer, an amino acid having a non-acidic side chain, a bis-pyridine compound, and a combination of two or more thereof. The polymer can be a cationic or nonionic polymer that comprises basic nitrogen groups, amide groups, or a combination thereof.

1 . A method of polishing germanium comprising the step of abrading the surface of a substrate comprising germanium with an aqueous chemical mechanical polishing (CMP) composition comprising an oxidizing agent, a particulate abrasive, and a germanium etching inhibitor comprising a cationic polymer selected from the group consisting of poly(diallyldimethylammonium)chloride (polyDADMAC), poly(methacryloyloxyethyltrimethylammonium)chloride (polyMADQUAT), poly(dimethylamine-co-epichlorohydrin-co-ethylenediamine) (polyDEE), and a copolymer of acrylamide and DADMAC, plus an amino acid selected from the group consisting of lysine, arginine, histidine, glycine, beta-alanine, tricine, and valine. 
     
     
         2 .- 10 . (canceled) 
     
     
         11 . A method of polishing germanium comprising the step of abrading the surface of a substrate comprising germanium with an aqueous chemical mechanical polishing (CMP) composition comprising an oxidizing agent, a particulate abrasive, and a germanium etching inhibitor comprising a bis-pyridine compound of formula Pyr-R′-Pyr, wherein each Pyr independently is a pyridine group attached to R′ at the 2, 3, or 4 position of the pyridine group; R′ is a covalent bond, (CH 2 )n, or CH═CH; and n is 1, 2, or 3. 
     
     
         12 . The method of  claim 11  wherein the bis-pyridine compound comprises at least one compound selected from the group consisting of 4,4′-trimethylenedipyridine, 1,2-bis(4-pyridyl)ethane, 2,2′-bipyridyl, and 1,2-bis(2-pyridyl)ethylene. 
     
     
         13 . The method of  claim 1  wherein the amino acid is present in the composition at a concentration in the range of about 50 to about 5000 parts-per-million (ppm). 
     
     
         14 . The method of  claim 1  wherein the water-soluble polymer is present in the CMP composition at a concentration in the range of about 10 to about 2000 ppm. 
     
     
         15 . The method of  claim 1  wherein the bis-pyridine compound is present in the composition at a concentration in the range of about 50 to about 5000 ppm. 
     
     
         16 . The method of  claim 1  wherein the particulate abrasive comprises colloidal silica at a concentration in the range of about 0.5 to about 3.5 percent by weight (wt %). 
     
     
         17 . The method of  claim 1  wherein the CMP composition comprises about 0.5 to about 3.5 wt % of the colloidal silica, and about 10 to about 2000 ppm of the water soluble polymer. 
     
     
         18 . The method of  claim 1  wherein the CMP composition comprises about 0.5 to about 3.5 wt % of the colloidal silica, and about 50 to about 5000 ppm of the amino acid. 
     
     
         19 . The method of  claim 1  wherein the CMP composition comprises about 0.5 to about 3.5 wt % of the colloidal silica, about 10 to about 2000 ppm of the polymer, and about 50 to about 5000 ppm of the amino acid. 
     
     
         20 . The method of  claim 1  wherein the oxidizing agent comprises hydrogen peroxide at a concentration in the range of about 0.5 to about 4 wt %.