Staircase Fin Strain Coupling via Pre-amorphization Implant
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In finFET devices, it is challenging to sustain strain in the small-sized fins due to their three-dimensional geometrical constraints, making it difficult to implement stress memorization techniques effectively.
Innovation Solution
The method involves forming staircase fin structures by etching trenches in a bulk substrate, creating shallow trench isolation regions, and using a pre-amorphization implant to introduce defects that couple strain into the fins, followed by a stress memorization technique anneal to propagate strain throughout the fins.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If stress memorization technique is applied to finFET devices, then drive current performance is improved, but the small size and three-dimensional geometrical constraints of fins make it difficult to sustain strain
Solution Approach 1:
The fin structure is divided into two distinct segments: a larger base portion embedded in the bulk substrate and a narrower top portion above the shallow trench isolation region. This segmentation allows the base portion to sustain strain from the bulk substrate while the top portion provides the necessary geometric constraints for the transistor channel, resolving the contradiction between strain sustainability and device performance.
Solution Approach 2:
The invention transitions from a conventional planar fin structure to a three-dimensional staircase fin structure with varying cross-sectional dimensions. By introducing vertical dimensionality variation (larger base, narrower top), the structure can simultaneously maintain strain from the bulk substrate and provide the geometric constraints needed for effective stress memorization in the channel region.
2Device complexity
If fins are isolated from larger bulk semiconductor materials, then finFET device structure is achieved, but it becomes very difficult to sustain strain in the fins
Solution Approach 1:
The fin structure is nested within the bulk substrate, with the larger base portion of the fin embedded in and coupled to the bulk semiconductor material. This nesting arrangement allows the fin to benefit from the strain field of the bulk substrate while maintaining the isolated finFET device structure, effectively resolving the contradiction between structural achievement and strain coupling.
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 enhances strain coupling and maintains channel region strain in finFETs, improving drive current performance by integrating strain into the top portions of the fins.
Implementation Method 1
A pre-amorphization implant is performed to generate defects in the substrate to couple strain into the top portions of the fins
Implementation Method 2
performing a stress memorization technique (SMT) anneal to propagate the strain after the pre-amorphization implant through the fins from the substrate
Implementation Method 3
Raised source ad drain regions are epitaxially grown on opposite sides of the gate structure
Data Source
AI summary
A method for forming strained fins includes etching trenches in a bulk substrate to form fins, filling the trenches with a dielectric fill and recessing the dielectric fill into the trenches to form shallow trench isolation regions. The fins are etched above the shallow trench isolation regions to form a staircase fin structure with narrow top portions of the fins. Gate structures are formed over the top portions of the fins. Raised source ad drain regions are epitaxially grown on opposite sides of the gate structure. A pre-morphization implant is performed to generate defects in the substrate to couple strain into the top portions of the fins.