GAA Metal Gate Sequencing for Precise Gate Height Control
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Solution Overview
Problem
Integration of gate-all-around (GAA) transistor features is challenging due to limitations in current fabrication methods, necessitating improved control over gate height and yield in semiconductor device structures.
Innovation Solution
A method involving double-patterning or multi-patterning processes is employed to form GAA structures, with a sacrificial layer patterned using photolithography and self-aligned spacers, followed by selective etching of metal gate layers to control height and improve yield.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional fabrication methods are used for GAA transistors, then the manufacturing process is simpler, but gate control and fabrication yield deteriorate
Solution Approach 1:
The fabrication process is divided into multiple patterning steps (double-patterning or multi-patterning) where the gate structure is formed in sequential stages. This segmentation allows precise control over gate height and dimensions while managing the complexity through structured process breakdown
Solution Approach 2:
A sacrificial layer is deposited and patterned before forming the actual gate structure. This preliminary action creates a template that guides subsequent gate formation, enabling precise gate height control and improved yield through self-aligned processes
2Productivity
If double-patterning or multi-patterning processes are employed, then gate height control and fabrication yield improve, but the fabrication process becomes more complex
Solution Approach 1:
Self-aligned spacers are formed that automatically position themselves relative to the sacrificial layer pattern. This self-alignment mechanism reduces the need for additional alignment steps and complex positioning procedures, thereby improving yield while managing process complexity
Solution Approach 2:
The sacrificial layer serves as an intermediary structure that facilitates the formation of the final gate pattern. It enables precise pattern transfer through selective etching and spacer formation, improving gate height control without requiring direct complex patterning of the gate material itself
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
Enhances gate control and improves the fabrication yield of GAA transistors by precise control over metal gate height and structure, addressing integration challenges.
Implementation Method 1
a sacrificial layer patterned using photolithography
Implementation Method 2
selective etching of metal gate layers to control height and improve yield
Data Source
AI summary
A method for forming a semiconductor device structure includes forming first nanostructures and second nanostructures over a substrate. The method also includes forming a first metal gate layer surrounding the first nanostructures and over the first nanostructures and the second nanostructures. The method also includes etching back the first metal gate layer over the first nanostructures and the second nanostructures. The method also includes removing the first metal gate layer over the second nanostructures. The method also includes forming a second metal gate layer surrounding the second nanostructures and over the first nanostructures and the second nanostructures.