Abstract: [Problem to be solved] Provided is a method for processing a substrate having high etching selectivity of silicon with respect to silicon-germanium and further having a high selection ratio of silicon with respect to a silicon oxide film and/or a silicon nitride film in surface processing when manufacturing various types of silicon devices, particularly various types of silicon composite semiconductor devices containing silicon-germanium. [Solution] A method for processing a substrate includes: bringing an etching solution into contact with a substrate including a silicon film and a silicon-germanium film to perform etching; and selectively removing the silicon film, in which the etching solution contains an organic alkali and water and has a dissolved oxygen concentration of 0.20 ppm or less.

Abstract: Silicon carbonitride with excellent dielectric and/or other properties may be used in manufacturing semiconductor devices. The manufacturing often requires etching silicon carbonitride without etching silicon oxide, but there is no known etching solution that sufficiently selectively etches silicon carbonitride containing carbon compared with silicon nitride used for the same purpose. An object of the present invention is to provide: an etching solution with a high etching selectivity ratio of silicon carbonitride to silicon oxide; a method of treating a substrate, the method including a step of bringing the etching solution into contact with the substrate; and a method of manufacturing a semiconductor device, the method including the method of treating a substrate. The object is achieved by an etching solution for etching silicon carbonitride, the etching solution composed of a homogeneous solution containing phosphoric acid, water, and a cerium ion.

Abstract: An object of the present invention is to provide an etching liquid having a high silicon etch selectivity with respect to silicon-germanium and a high long term stability at a processing temperature, in surface processing during the production of various semiconductor devices, especially various silicon composite semiconductor devices containing silicon-germanium, and the problem is solved by a silicon etching liquid containing an alkaline compound, an aldehyde compound, and water, the aldehyde compound being a water-soluble aromatic aldehyde.