Nanostructure Gate Stack Layout for Scaled Transistor Geometry Control
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Solution Overview
Problem
The challenge in the semiconductor industry is to form reliable semiconductor devices at increasingly smaller sizes due to the complexity and difficulty of fabrication processes as feature sizes decrease, affecting production efficiency and cost.
Innovation Solution
The process involves forming nanostructure transistors using double-patterning or multi-patterning techniques, including the creation of nanostructures such as nanowires and nanosheets, with specific thicknesses and germanium concentrations, and the use of spacer layers and gate stacks to pattern and isolate these structures, enabling precise control over device geometry and performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If feature sizes continue to decrease to increase functional density, then production efficiency improves and costs降低, but fabrication process complexity and difficulty increase
Solution Approach 1:
The fabrication process is divided into multiple discrete stages including forming sacrificial nanostructure stacks, creating spacers, selectively removing portions, and forming gate structures. This segmentation allows each step to be optimized independently while maintaining overall process control despite the reduced feature sizes
Solution Approach 2:
Sacrificial nanostructure stacks are formed in advance before the actual transistor structures are created. These preliminary structures serve as templates that guide subsequent processing steps, enabling precise pattern transfer at smaller dimensions while simplifying the overall fabrication sequence
2Quantity of substance
If feature sizes decrease to increase functional density, then more devices fit per chip area, but reliability of individual devices becomes harder to ensure
Solution Approach 1:
The gate structure is designed with all-around coverage of the channel region, providing enhanced local control of carrier flow at each specific location. This localized control ensures reliable device operation even as individual feature dimensions shrink, maintaining device reliability while increasing overall device density
Solution Approach 2:
The gate structure completely surrounds the channel region in a nested configuration, with the gate electrode enveloping the semiconductor channel from multiple directions. This nested arrangement provides superior electrostatic control and ensures reliable device performance at scaled dimensions by maintaining strong electric field control throughout the channel
3Manufacturing precision
If double-patterning or multi-patterning techniques are used to form nanostructures, then precise control over device geometry is achieved, but manufacturing process complexity increases
Solution Approach 1:
Spacer structures are formed through self-aligned deposition processes where the spacer material automatically conforms to the sacrificial nanostructure sidewalls. This self-service approach achieves precise geometric control and alignment without requiring additional alignment steps or complex patterning equipment, reducing manufacturing complexity while maintaining high precision
Data Source
AI summary
A method for forming a semiconductor device structure is provided. The method includes providing a substrate. The method includes forming a nanostructure stack over the substrate. The method includes forming a gate stack over the nanostructure stack and the substrate. The method includes removing the first nanostructure forming a first gap between the substrate and the second nanostructure. The method includes forming a first spacer layer in the first gap and a gate spacer over a sidewall of the gate stack. The method includes partially removing the nanostructure stack, which is not covered by the gate stack and the gate spacer, to form a first trench in the nanostructure stack. The method includes forming a source/drain structure in the first trench and over the first spacer layer.