Mandrel Removal in Lateral Semiconductor Growth
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The challenge in semiconductor manufacturing is growing defect-free III-V material on silicon sidewalls, as removing the mandrel can cause the fin structure to collapse, leading to anchoring issues that may result in density trade-offs.
Innovation Solution
The method involves forming elongated mandrels with cap layers on a dielectric layer, covering them with sacrificial gates and spacer walls, growing III-V semiconductor fin structures, and then removing the mandrel and sacrificial gate structures to create unsupported semiconductor channel fins, allowing for the formation of a functional gate structure in the vacant space.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If mandrels are removed after growing III-V material on silicon sidewalls, then defect-free III-V material can be obtained, but fin structure collapse occurs leading to anchoring issues
Solution Approach 1:
The patent applies preliminary action by forming sacrificial gate structures and spacer walls before mandrel removal. The sacrificial gates are deposited and patterned to cover the mandrels, and spacer walls are formed on the sacrificial gates. These structures are prepared in advance to provide support during the mandrel removal process, preventing fin collapse while enabling defect-free III-V material growth.
Solution Approach 2:
The patent uses sacrificial gate structures and spacer walls as intermediary elements. The sacrificial gates serve as temporary supporting structures that maintain fin stability during mandrel removal. The spacer walls formed on the sacrificial gates provide additional mechanical support. These intermediary structures are removed later after serving their protective function, resolving the contradiction between obtaining defect-free material and maintaining structural stability.
2Stability of the object's composition
If mandrels are kept to support fin structures, then structural integrity is maintained, but density trade-offs occur due to anchoring issues
Solution Approach 1:
The patent applies discarding and recovering by using temporary sacrificial gate structures that are discarded after serving their support function. The sacrificial gates are formed to provide structural integrity during manufacturing, then removed after the fins are grown and stabilized. This allows high device density to be achieved without permanent anchoring structures, resolving the contradiction between maintaining fin integrity and maximizing device density.
3Ease of manufacture
If mandrels are removed early, then manufacturing process is simplified, but fin structure collapse occurs
Solution Approach 1:
The patent applies preliminary action by preparing sacrificial gate structures and spacer walls before mandrel removal. The sacrificial gates are deposited conformally and patterned in advance, and spacer walls are formed on the sacrificial gates before the mandrels are removed. This preliminary preparation maintains fin structure strength during removal while keeping the overall process systematic and manageable.
Solution Approach 2:
The patent uses sacrificial gate structures as intermediary elements that mediate between the mandrels and the final fin structure. These intermediaries provide temporary strength during the critical mandrel removal step, preventing collapse. The intermediaries are designed to be removed cleanly after serving their protective function, achieving both process feasibility and structural integrity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enables lateral semiconductor growth that avoids fin structure collapse, maintaining structural integrity while allowing for further growth and integration of source and drain regions, effectively addressing the anchoring and density trade-off challenges.
Implementation Method 1
growing semiconductor fin structures on the plurality of mandrel elements
Data Source
AI summary
A method of forming a semiconductor structure is disclosed comprising removing mandrel elements, the side walls of which support semiconductor fin structures, which mandrel elements are formed by removing portions of each of a plurality of elongated mandrels outside sacrificial gate structures, wherein the mandrel elements are removed after removing the sacrificial gate structure. Also disclosed is an intermediate semiconductor structure, obtained during some embodiments of the method, comprising a plurality of mandrel elements, a plurality of fin channel structures, source regions and drain regions on opposing sides of the fin channel structures wherein the bottom most surface of the fin channel structures and the source and drain regions are in direct physical contact with a common dielectric layer on a silicon-containing substrate.