42results about How to "Guaranteed etching effect" patented technology

The invention provides an LDMOS device and a preparation method thereof, and belongs to the technical field of semiconductors, and the preparation method comprises the steps: providing a substrate, forming a first oxidation material with a preset thickness on the substrate, and forming a first oxidation layer; forming a dielectric material layer, and performing ion implantation on the substrate around the first oxide layer by using the dielectric material layer; a preset photomask is adopted to perform patterning on the dielectric material layer, the surface of the substrate is exposed, the remaining dielectric material layer covering the surface of the first oxide layer serves as a dielectric layer, the remaining dielectric material layer covering the side wall of the first oxide layer serves as a side wall layer, and the dielectric layer is connected with the side wall layer; a second oxide layer is formed on the surface of the substrate, the second oxide layer is connected with the side wall layer, and the thickness of the second oxide layer is smaller than the preset thickness; a conductive layer is formed, and a patterning process is performed to form a field oxide structure and a field plate. The performance of the ROX structure in the LDMOS device can be improved, and the preparation process of the ROX structure can be simplified.

The application relates to the technical field of semiconductor and electronic chemicals, and particularly discloses an etching solution for selectively etching silicon nitride and titanium nitride and a preparation method thereof. The etching solution contains the following components in percentage by mass: 10-45% of phosphoric acid, 1-5% of hydrofluoric acid, 0.5-2.5% of a pH buffer, 0.01-1.8% of a solubilizer and 0.1-7% of an etching inhibitor, and the rest is water. The pH buffer can effectively stabilize the pH of the etching solution, the solubilizer can improve the solubility of the solvent in the etching solution, reduce the tension of the solid-liquid phase interface in the solution and promote the transmission rate of the interphase substances, and the etching inhibitor can form a film on the surface of the titanium nitride in the form of a coordination bond, so that the silicon nitride and the titanium nitride have a high selectivity ratio. The etching solution can inhibit the etching rate of the titanium nitride under the condition of a high etching rate of the silicon nitride, and can ensure the high selectivity ratio of the silicon nitride and the titanium nitride.