PREFERENTIAL ETCH OF SEMICONDUCTOR SUBSTRATE WITH RESPECT TO EPITAXIAL LAYERS

摘要

An etching composition and method for its use in etching a semiconductor structure, the semiconductor structure comprising a substrate and one or more epitaxial layers. The etching composition comprises a solvent, an etchant, and first and second complexing agents, the etchant and complexing agents being soluble in the solvent. The etchant preferentially etches the substrate with respect to at least one epitaxial layer. The first complexing agent is reactive with the substrate so as to accelerate the rate at which the etchant etches the substrate. The second completing agent is reactive with a component of the at least one epitaxial layer so as to form a resulting compound with the component. This reaction establishes an equilibrium between the resulting compound, the second complexing agent and the component, the equilibrium precluding significant etching of the at least one epitaxial layer. The etching composition preferably comprises an agent which provides for adjusting the acidity of the solution, and thereby provides for adjusting the etch rate of the substrate while maintaining the composition's etching characteristics with respect to the at least one epitaxial layer.