Backside Contact GAA Semiconductor Structure With Etch-Stop Isolation
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Solution Overview
Problem
The challenge of forming reliable semiconductor devices at smaller sizes is exacerbated by the complexity of fabrication processes as feature sizes continue to decrease, making it difficult to achieve efficient and reliable manufacturing.
Innovation Solution
The use of multi-patterning photolithography and self-aligned processes to create semiconductor structures, such as FinFETs and gate all around (GAA) transistors, with alternating sacrificial and channel layers, and the formation of dielectric and protection structures to enhance etching selectivity and oxidation rates, along with epitaxial growth techniques to form semiconductor layers and epitaxial structures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If feature sizes continue to decrease to increase functional density, then production efficiency and cost are improved, but fabrication process complexity and manufacturing reliability deteriorate
Solution Approach 1:
The patent transitions from planar 2D device structures to three-dimensional FinFET and GAA transistor architectures. This dimensional change enables continued scaling of functional density while managing fabrication complexity through vertical channel structures that provide better electrostatic control and reduced parasitic effects compared to traditional planar devices
Solution Approach 2:
The patent implements gate-all-around structures where the gate electrode completely surrounds the channel in three dimensions, and nested epitaxial layers in GAA transistors where multiple semiconductor layers are stacked and enclosed by gate structures. This nesting approach maximizes gate control over the channel while maintaining compact footprints, enabling higher density without proportionally increasing process complexity
2Productivity
If feature sizes continue to decrease to increase functional density, then production efficiency and cost are improved, but manufacturing reliability deteriorates
Solution Approach 1:
The patent employs precise control of material composition parameters in alternating epitaxial layers, varying semiconductor material compositions (e.g., SiGe/Si ratios) to achieve desired strain levels, carrier concentrations, and etch selectivities. These parameter optimizations enable reliable formation of nanoscale features with controlled electrical characteristics and improved device performance consistency
Solution Approach 2:
The patent performs preliminary epitaxial growth of alternating semiconductor layers with predetermined compositions and thicknesses before any patterning or etching steps. This preliminary structuring establishes self-aligned features and pre-defined material properties that guide subsequent processing, reducing variability and improving manufacturing yield at scaled dimensions
3Length of moving object
If multi-patterning photolithography and self-aligned processes are used to create smaller structures, then device miniaturization is achieved, but fabrication process complexity increases
Solution Approach 1:
The patent utilizes self-aligned epitaxial growth where alternating semiconductor layers automatically form with precise interfaces and thicknesses based on previous layer deposition. This self-alignment eliminates the need for multiple photolithography alignment steps, reducing process complexity while achieving the required dimensional precision for scaled devices
Solution Approach 2:
The patent divides the channel structure into multiple thin epitaxial layers with alternating compositions, where each layer serves a specific functional purpose (e.g., barrier, channel, strain-induced). This segmentation enables independent optimization of each layer's properties and simplifies the overall fabrication by using repeated deposition cycles rather than complex single-step processes
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 creation of semiconductor devices with improved reliability and efficiency by enabling the formation of smaller, more complex circuits with reduced parasitic capacitance and enhanced current flow, thereby addressing the challenges of miniaturization in semiconductor fabrication.
Implementation Method 1
epitaxial growth techniques to form semiconductor layers and epitaxial structures
Data Source
AI summary
A semiconductor device structure is provided. The semiconductor device structure includes a stack of channel structures and a first epitaxial structure and a second epitaxial structure adjacent to opposite sides of the channel structures. The semiconductor device structure also includes a gate stack wrapped around the channel structures and a backside conductive contact connected to the second epitaxial structure. The second epitaxial structure is between a top of the backside conductive contact and a top of the gate stack. The semiconductor device structure further includes an etch stop layer extending along a sidewall of the backside conductive contact and a bottom of the gate stack.