Stacked Oxide Semiconductor Channel for Voltage Stability and Mobility
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Solution Overview
Problem
Existing semiconductor devices with oxide semiconductor channel layers face challenges in achieving stable threshold voltage and high carrier mobility due to uniformity and composition issues in the channel layer.
Innovation Solution
A two-stage atomic layer deposition process is used to form the oxide semiconductor channel layer, dividing it into two portions with different metal composition concentrations along the thickness direction, where the portion closer to the gate has a higher metal concentration and is composed of alternately stacked oxide semiconductor materials, while the portion farther from the gate has a lower concentration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a uniform oxide semiconductor channel layer is formed using conventional deposition methods, then the manufacturing process is simple, but the threshold voltage stability and carrier mobility cannot be simultaneously optimized
Solution Approach 1:
The oxide semiconductor channel layer is segmented into multiple sub-layers with different metal composition concentrations. The first stacked channel layer has a lower metal composition concentration while the second stacked channel layer has a higher metal composition concentration. This segmentation allows each sub-layer to contribute differently to device performance, with the higher concentration layer near the gate improving threshold voltage stability and the lower concentration layer maintaining carrier mobility.
Solution Approach 2:
Different regions of the channel layer are assigned different metal composition concentrations to optimize local properties. The portion closer to the gate structure has a higher metal composition concentration to stabilize threshold voltage, while the portion farther from the gate has a lower concentration to maintain high carrier mobility. This local quality differentiation resolves the contradiction between threshold voltage stability and carrier mobility.
2Reliability
If the metal composition concentration is increased to improve carrier mobility, then carrier mobility increases, but threshold voltage stability deteriorates
Solution Approach 1:
The channel layer is designed with spatially varying metal composition concentrations. The first stacked channel layer with lower metal composition concentration is positioned to maintain carrier mobility, while the second stacked channel layer with higher metal composition concentration is positioned near the gate to stabilize threshold voltage. This local quality approach allows both parameters to be optimized in their respective regions.
Solution Approach 2:
The solution transitions from a uniform one-dimensional channel layer to a multi-layered structure with variation in the thickness direction. By introducing compositional gradient along the thickness dimension, the patent simultaneously achieves high carrier mobility in the bulk and stable threshold voltage at the gate interface.
3Reliability
If a two-stage atomic layer deposition process is used to create non-uniform metal composition concentrations, then threshold voltage stability and carrier mobility are simultaneously achieved, but the manufacturing complexity increases
Solution Approach 1:
The deposition process is segmented into two distinct stages: a first atomic layer deposition cycle performed M times to form the first stacked channel layer with lower metal composition concentration, and a second atomic layer deposition cycle performed N times to form the second stacked channel layer with higher metal composition concentration. This process segmentation enables precise control over the compositional profile.
Solution Approach 2:
The deposition process utilizes parameter changes between the two stages, specifically varying the metal precursor dosage or deposition conditions to achieve different metal composition concentrations in each stacked layer. This parameter control allows the formation of the desired compositional gradient that simultaneously optimizes threshold voltage stability and carrier mobility.
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 enables the concurrent achievement of stable threshold voltage and increased carrier mobility by optimizing the channel layer's composition and structure.
Implementation Method 1
A first atomic layer deposition cycle is performed M times to form a first stacked channel layer on the substrate. A second atomic layer deposition cycle is performed N times to form a second stacked channel layer on the first stacked channel layer
Data Source
AI summary
A method for forming a metal oxide semiconductor device includes performing a first atomic layer deposition cycle M times to form a first stacked channel layer and a second atomic layer deposition cycle N times to form a second stacked channel layer on the first stacked channel layer. M and N are positive integers. The first stacked channel layer and the second stacked channel layer have different metal compositions and collectively form the channel layer of the metal oxide semiconductor device.