Novel siloxane polymer compositions

Abstract

A siloxane composition and a method of producing the same. The composition comprises a siloxane prepolymer with a backbone exhibiting a group which is capable of being deprotonated in an aqueous base solution. Further, there are reactive functional groups, which are capable of reacting during thermal or radiation initiated curing. The siloxane is cross-linked during condensation polymerisation to increase molecular weight thereof. The composition can be used in high-resolution negative tone lithographic fabrication processes where a water based developer system is applied in the development step of the lithography process.

What is claimed is: 
     
         1 . A siloxane composition, comprising
 a siloxane prepolymer with a siloxane backbone exhibiting a group which is capable of being deprotonated in an aqueous base solution and further exhibiting a reactive functional group, which is capable of reacting during a thermal or radiation initiated curing step, said siloxane prepolymer having been cross-linked during polymerisation to increase the molecular weight thereof,   a solvent for the siloxane prepolymer and   a photo reactive compound.   
     
     
         2 . The composition according to  claim 1 , wherein the siloxane prepolymer has an average molecular weight of about 2,000 to 20,000 g/mol, in particular about 3,000 to 10,000 g/mol. 
     
     
         3 . The composition according to  claim 1 , having a solid concentration of at least 1 weight-% and up to about 70 weight-%. 
     
     
         4 . The composition according to  claim 1 , wherein the organosiloxane polymer contains at least 1 mole-%, in particular at least 5 mole-% units derived from monomers comprising at least one group which is capable of being deprotonated. 
     
     
         5 . The composition of  claim 1 , wherein the solvent is a solvent capable of reacting with the siloxane prepolymer. 
     
     
         6 . The composition according to  claim 5 , wherein the solvent is selected from the group of water, aliphatic alcohols, aliphatic ethers, and aromatic alcohols and mixtures thereof. 
     
     
         7 . The composition according to  claim 5 , wherein the solvent is selected from the group of propylene glycol monomethylether, propylene glycol propyl ether, 2-propanol, water, ethanol, methanol and ethyl lactate and mixtures thereof. 
     
     
         8 . The composition according to  claim 1 , wherein the photo reactive compound is a photo acid generator or photo initiator. 
     
     
         9 . The composition according to  claim 8 , wherein the photo reactive compound is capable of cross-linking the siloxane composition subject to treatment with ultraviolet light or thermally. 
     
     
         10 . The composition according to  claim 9 , wherein the composition contains a thermo acid generator as an additive. 
     
     
         11 . The composition according to  claim 1 , wherein the concentration of the photo reactive compound is about 0.1 to 10%, preferably about 0.5 to 5%, calculated from the mass of the siloxane polymer. 
     
     
         12 . The composition according to  claim 1 , comprising solid nanoparticles in an amount of between 5 and 50 wt-% of the composition. 
     
     
         13 . The composition according to  claim 12 , wherein the nanoparticles are selected from the group of light scattering pigments and inorganic phosfors. 
     
     
         14 . A siloxane composition comprising a siloxane prepolymer in a solvent phase,
 said prepolymer having a siloxane backbone formed by repeating —Si—O— units and having a molecular weight in the range of from about 4,000 to about 10,000 g/mol, said siloxane backbone exhibiting hydroxyl groups in an amount of about 5 to 70% of the —Si—O— units and further exhibiting epoxy groups in an amount of 1 to 15 mol %, calculated from the amount of repeating units; and   said composition further comprising 0.1-3%, based on the weight of the solid matter, at least one cationic photo reactive compound.   
     
     
         15 . The composition according to  claim 14 , wherein the solvent phase comprises a solvent selected from the group of propylene glycol monomethylether, propylene glycol propyl ether, 2-propanol, water, ethanol, methanol and ethyl lactate and mixtures thereof. 
     
     
         16 . A method of using a siloxane prepolymer composition according to  claim 1  in a lithographic method comprising the steps of
 optionally adjusting the solid contents of the prepolymer composition material to the required film thickness of the deposited film, 
 depositing the composition on a substrate to form a layer having a film thicknesses of 10 nm-10 μm, 
 optionally heat treating the deposited film, 
 subjecting the deposited material layer to lithography by using a photo mask or reticle and exposing the material to UV light, 
 optionally heat treating the exposed material, and 
 removing the non-exposed areas of the film are removed in a development step, by contacting the layer with an aqueous basic developer solution. 
 
     
     
         17 . The method according to  claim 16 , wherein the aqueous base developer solution has a pH of at least 7, preferably at least 9. 
     
     
         18 . The method according to  claim 17 , wherein the aqueous base developer solution has a pH of least 11, preferably at least 12, in particular about 12 to 13. 
     
     
         19 . The method according to  claim 16 , wherein a film is produced having a dielectric constant of 4 or below at a frequency of 100 kHz. 
     
     
         20 . The method according to  claim 16 , wherein a film is produced having an index of refraction which is between 1.2 to 1.9 at a wavelength of 633 nm. 
     
     
         21 . The method according to  claim 16 , wherein a film is produced exhibiting a cross-linking degree of 70% or more at a UV dose of 100 mJ/cm 2  or less at I-line wavelength of mercury UV source. 
     
     
         22 . The method according to  claim 16 , wherein a film is produced having a resolution better than 3 μm, preferably better than 1 μm. 
     
     
         23 . The method according to  claim 16 , wherein a film is produced having an aspect ratio of 1:1 or more, preferably 1:1,5 or more. 
     
     
         24 . The method according to  claim 16 , comprising patterning the material compositions by direct lithographic patterning, by conventional lithographic masking and etching procedure, or by imprinting and embossing. 
     
     
         25 . The method according to  claim 16 , comprising providing an optical layer in a display device, such as an LCD, Plasma or OLED display), a solar cell, an LED or a semiconductor device.