Abstract: Disclosed herein is a composition for selectively etching a first silicon germanium layer having a first germanium content in the presence of a silicon layer or a second silicon germanium layer having a second germanium content, where the first germanium content is higher than the second germanium content, the composition including: (a) from 0.1 to 10% by weight of an oxidizing agent; (b) from 1 to 20% by weight of an etchant including a source of fluoride ions; (c) from 0.001 to 3% by weight of a selectivity enhancer of formula Si (d) from 0.001 to 3% by weight of an additional selectivity enhancer of formula S41 or derivatives thereof obtained by homocondensation of the compounds of formula S41 or by co-condensation of the compounds of formula S41 with silanes of formula S42 in a weight ratio of 0.1 or more and (e) water.

Abstract: Disclosed herein is a composition for selectively etching a silicon germanium (SiGe) layer in the presence of a silicon layer, the composition including: (a) 1 to 10% by weight of an oxidizing agent; (b) 1 to 14% by weight of an etchant comprising a source of fluoride ions; (c) 0.001 to 3% by weight of a selectivity enhancer of formula S1 (d) 0.001 to 3% by weight of an additional selectivity enhancer of formula S31 and (e) water.

Abstract: Disclosed herein is a composition for selectively etching a layer including a silicon germanium alloy (SiGe) in the presence of a layer including silicon, the composition including: (a) 5 to 15% by weight of an oxidizing agent; (b) 5 to 20% by weight of an etchant comprising a source of fluoride ions; (c) 0.001 to 3% by weight of a first selectivity enhancer of formula S1 and (d) water.

Abstract: A method for producing an optical waveguide includes following steps: firstly, providing a substrate and coating resins on the substrate to form a clad; secondly, providing a container filled with waveguide material and inject the waveguide material through a nozzle of the container to form a shape needed on the clad; thirdly, shining UV lights on the waveguide material to harden the waveguide material to form the waveguide. This new method uses less waveguide material and simplifies the steps.