Spin coating oxide substrates

The polymer resists used in this study were either synthesized in-house or obtained from Aldrich Chemicals or Polyscience, Inc. Photoresist samples were obtained from KTI Chemicals or the manufacturer. The polymers were dissolved in suitable solvents and spin coated onto oxidized Si wafers or Cr-coated glass test substrates. The polymer film thicknesses were measured either by a Taylor-Hobson proficorder or Tencor Alpha-step. 

AZ-1350 photoresist was used as a thick bottom layer polymer. AZ resist, thicker than 1.0 was spin-coated on silicon wafer (oxide coated) or substrate with topographic features. The resist was hard-baked for 1 hour at 200 C. SNR film was then spin-coated on a hard-baked AZ resist layer from 5 wt% solution in methylisobutylketone. 

For example, PTV film was fabricated as follows. Polymerization of a sulphonium monomer, 2,5-thienylene bis (methylene-dimethyl-sulphonium chloride) was carried out in a methanol-water mixture at -20°C by adding a methanol solution of tetramethyl-ammonium hydroxide. The reaction was quenched by an addition of hydrochloric acid. A yellow precipitate (precursor polymer) appeared as the solution was warmed to room temperature. The precipitated precursor polymer was completely soluble in dich-loromethane. A precursor polymer thin film was obtained by spin-coating of the dichloromethane solution of the precursor polymer onto a fused silica glass substrate under inert atmosphere to prevent oxidation with air. The film was heated at 200-250°C in a vacuum of 10"2 Torr for 5 hours, to give a tough, flexible PTV film. The resulting PTV thin film was chemically stable in air. 

Polymer films were prepared by spin-coating, under controlled inert atmosphere, from typically a 1 mg/ml solution of the polymer in appropriate solvents. Films were generally made on aluminum (with a natural oxide of about 20 A), or on gold. The metals were in the form of vapor-deposited films, of about 2000-3000 A in thickness, deposited in UHV on the surfaces of optically flat Si( 110) substrates. Occasionally, the bare (natural oxide) surface of the Si substrate was used directly, depending upon the preferences for film formation displayed by the particular polymer/solvent combination, or to... 

Two 0.9" X 1.2" X 1 mm thick soda lime glass substrates containing transparent indium-tin-oxide were spin-coated and cured with the Step 4 product by heating thin films in air for 15 minutes at 80°C and for 60 minutes at 200°C. 

The first step was to spin-coat an electron-sensitive polymer (polymethylmethacrylate (PMMA)) onto an oxidized Si(l 00) wafer (which serves as a Si02 support). The desired pattern is subsequently written into the polymer layer by a highly collimated electron beam, followed by the selective dissolution of the polymer damaged by the electron exposure. A thin film of platinum is then deposited on this mask, and after the remaining polymer resist is removed completely by dissolution, metal particles remain on the substrate and are located at the positions of the prior electron irradiation, typically forming an ordered array of nanoparticles. 

Gold arrays are prepared by electron beam lithography (EBL) according to the following method. The bare substrate is a glass plate (10 mm X 10 mm) on which a thin indium tin oxide (ITO) substrate is evaporated. The ITO substrate is then spin coated (60 s, at 5000 rpm) with a 100 nm thick Poly methyl-methacrylate (PMMA) polymer,... 

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