Epitaxial Block Layer for FinFET Uniform Growth
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
FinFET devices face challenges in achieving uniform epitaxial growth and ideal facet formation due to non-ideal epitaxy of source and drain, leading to asymmetric growth and potential leakage paths, which complicates contact placement and current crowding issues.
Innovation Solution
A method involving the formation of a dummy gate, spacer layer, and epitaxial block layer over FinFETs, with recesses created in the substrate before removing the epitaxial block layer to enable uniform epitaxial growth by forming epi material within these recesses, ensuring proper stress and facet formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional lithography and etch techniques are used to pattern isolation trench, then the process is simple and familiar, but the critical dimensions required cannot be achieved
Solution Approach 1:
The isolation structure is segmented into multiple components: shallow trench isolation (STI) oxide layers at different depths, dummy gates, and epi blocks. This segmentation allows each component to be formed with appropriate process techniques, achieving the required critical dimensions through self-aligned processes rather than attempting to pattern the entire isolation structure in a single step.
Solution Approach 2:
The patent transitions from two-dimensional planar patterning to three-dimensional vertical structuring. By forming STI oxide in recesses at different depths and creating dummy gates that extend vertically, the isolation structure achieves the required precision through vertical dimension control rather than relying solely on lateral lithographic resolution.
2Manufacturing precision
If epi growth is performed without proper isolation structure, then the process is simpler, but asymmetric growth and non-ideal facets occur
Solution Approach 1:
The shallow trench isolation oxide and dummy gate structures are formed preliminarily before the epitaxial growth step. These pre-formed structures serve as templates and barriers that guide the subsequent epi growth, ensuring uniform and symmetric facet formation. The preliminary structures define the geometry into which the epi material will grow, preventing asymmetric growth patterns.
Solution Approach 2:
The dummy gate and STI oxide structures act as intermediary elements between the substrate and the epitaxial growth process. These intermediaries control the growth environment by providing physical barriers and defining the growth geometry, thereby mediating the interaction between the epi material and the underlying structure to achieve uniform growth and ideal facets.
3Reliability
If dummy gate is used to isolate epi junction, then isolation is achieved, but leakage paths still exist through the dummy gate
Solution Approach 1:
The dummy gate structure, which initially appears to be a potential leakage path, is converted into a beneficial isolation element. By forming the dummy gate from the same epi material as the source and drain regions and integrating it into the self-aligned process, the structure that could potentially cause leakage instead provides mechanical support and defines the isolation geometry, while the actual electrical isolation is achieved through the STI oxide and junction depth control.
4Manufacturing precision
If contact area is not positioned high on epi structure, then the epi growth is simpler, but current crowding issues occur
Solution Approach 1:
The patent controls the vertical position of the contact area by adjusting epi growth parameters and the geometry of the underlying STI oxide and dummy gate structures. By changing the depth and dimensions of the isolation recesses and the height of the dummy gate, the contact area is positioned at the optimal height on the epi structure, maximizing current flow efficiency and preventing current crowding while maintaining uniform epi growth.
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 results in uniform epitaxial growth, reducing leakage and current crowding issues, and enhances electrostatic control over carriers, improving the overall performance of FinFET devices.
Implementation Method 1
forming an epi material within a set of recesses in the substrate, the set of recesses formed prior to removal of an epi block layer
Data Source
AI summary
Approaches for enabling uniform epitaxial (epi) growth in an epi junction area of a semiconductor device (e.g., a fin field effect transistor device) are provided. Specifically, a semiconductor device is provided including a dummy gate and a set of fin field effect transistors (FinFETs) formed over a substrate; a spacer layer formed over the dummy gate and each of the set of FinFETs; and an epi material formed within a set of recesses in the substrate, the set of recesses formed prior to removal of an epi block layer over the dummy gate.