Sub-Nanometer Germanium Cladding for Semiconductor Channel Structures
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Solution Overview
Problem
The scaling down of semiconductor devices, such as finFETs and nanowires, poses challenges in forming a uniform germanium cladding layer due to pattern geometry shadowing and the inability of existing methods to accommodate thin thicknesses required for advanced device structures.
Innovation Solution
A method involving reduced pressure CVD tools and specific process conditions is used to epitaxially grow a thin germanium cladding layer on silicon channels, followed by annealing, to form a uniform germanium or silicon-germanium alloy layer with a thickness less than 1 nm, which is achieved through controlled Ge treatment and annealing cycles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional CVD methods are used to grow germanium cladding layer, then the process is simple, but the layer thickness cannot be controlled below 1 nm and uniformity is poor due to pattern geometry shadowing
Solution Approach 1:
The germanium cladding layer formation is divided into multiple sequential steps: (1) forming a sacrificial mandrel pattern, (2) depositing germanium material conformally over the mandrel, (3) removing the mandrel, and (4) performing atomic layer deposition (ALD) to achieve uniform thin films. This segmentation allows precise thickness control and eliminates pattern geometry shadowing effects.
Solution Approach 2:
A sacrificial mandrel pattern is formed beforehand to define the final cladding layer geometry. The mandrel serves as a temporary structure that enables conformal germanium deposition and subsequent removal, allowing precise control over the final thin film thickness and uniformity without shadowing effects.
2Length of moving object
If the germanium cladding layer is made thinner to maintain gate structure space, then device scaling is enabled, but uncontrolled island mergers occur during annealing
Solution Approach 1:
The annealing process incorporates monitoring and adjustment mechanisms to control germanium island formation and merging. Process parameters such as temperature, time, and atmosphere are dynamically adjusted based on observed island behavior to prevent uncontrolled mergers while maintaining thin film thickness for device scaling.
Solution Approach 2:
The annealing process uses controlled parameter changes (temperature profiles, atmosphere composition, duration) to manage germanium island dynamics. By carefully adjusting these parameters, the process prevents unwanted island mergers while enabling thin cladding layer formation for reduced channel spacing.
3Manufacturing precision
If advanced patterning methods are used to achieve thin uniform cladding layers, then manufacturing precision improves, but the manufacturing process becomes more complex
Solution Approach 1:
A sacrificial mandrel material serves as an intermediary that facilitates the formation of uniform thin germanium cladding layers. The mandrel enables conformal deposition and precise thickness control through its geometric definition, and is subsequently removed to leave the desired thin uniform film, simplifying the overall manufacturing process despite the additional step.
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 allows for the formation of a uniform germanium cladding layer that reduces pFET threshold voltages, maintains sufficient space for gate structures, and prevents device performance failures by avoiding uncontrolled island mergers.
Implementation Method 1
forming a germanium epitaxial growth layer on the plurality of first nanostructured layers
Implementation Method 2
annealing the germanium epitaxial growth layer... to form a cladding layer surrounding the first nanostructured layers
Data Source
AI summary
The present disclosure provides channel structures of a semiconductor device and fabricating methods thereof. The method can include forming a superlattice structure with first nanostructured layers and second nanostructured layers on a fin structure. The method can also include removing the second nanostructured layers to form multiple gate openings; forming a germanium epitaxial growth layer on the first nanostructured layers at a first temperature and a first pressure; and increasing the first temperature to a second temperature and increasing the first pressure to a second pressure over a first predetermined period of time. The method can further include annealing the germanium epitaxial growth layer at the second temperature and the second pressure in the chamber over a second predetermined period of time to form a cladding layer surrounding the first nanostructured layers.