Semiconductor Capping Structure Thickness Uniformity

The patent applies preliminary action by forming a first capping layer before the second capping layer, where the first capping layer serves as a foundation that can be selectively removed or modified. This preliminary structure allows for subsequent processing steps to achieve uniform final thickness despite different underlying crystal planes, as the first capping layer can be etched back to expose different amounts of underlying material that will be covered by the second capping layer.

The patent implements local quality by treating different regions of the epitaxial layer differently. Regions with different crystal planes (e.g., <100> and <111> planes) receive different amounts of capping layer material or undergo different etching processes. This allows each region to be compensated for its specific etching rate, achieving overall uniformity while accounting for local variations in crystal orientation.

The patent applies parameter changes by modifying the crystal plane orientation of the epitaxial layer regions. By growing epitaxial layers with specific crystal planes (such as <111> or <100> planes) in different regions, the carrier mobility is enhanced through the inherent properties of these crystal orientations. This approach achieves mobility improvement through material parameter selection rather than complex strain engineering processes.

The patent uses composite materials by combining epitaxial layers with different crystal plane orientations in a single device structure. Different regions of the semiconductor device utilize epitaxial layers grown on different crystal planes, creating a composite structure that leverages the advantages of each orientation for carrier mobility while maintaining a relatively straightforward fabrication process compared to conventional strained silicon approaches.