Oxide Semiconductor Channel Structure for DRAM Leakage Reduction
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Solution Overview
Problem
As semiconductor devices, particularly DRAM devices with a 1T-1C structure, are downscaled, the leakage current through the channel region increases, necessitating the use of oxide semiconductor materials for transistors to mitigate this issue.
Innovation Solution
The semiconductor device incorporates a channel layer with an oxygen-rich region in its upper portion, utilizing an oxide semiconductor material and a specific structure with a U-shape and opposing vertical extending portions, along with a gate insulating layer, word lines, and capacitor structures to reduce leakage current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If oxide semiconductor material is used in the channel layer, then leakage current is reduced, but manufacturing complexity increases due to the need for oxygen-rich region formation and precise structural control
Solution Approach 1:
The channel layer is designed with spatially varying oxygen concentration, creating an oxygen-rich region in the upper portion and an oxygen-poor region in the lower portion. This local quality variation optimizes both leakage current reduction (through oxygen-rich regions) and carrier mobility (through oxygen-poor regions), while the gradual transition avoids abrupt interfaces that would increase manufacturing complexity.
Solution Approach 2:
The oxygen concentration parameter is varied continuously or in steps through the channel layer thickness. By controlling the oxygen concentration gradient during deposition or through subsequent annealing processes, the patent achieves reduced leakage current while maintaining manageable manufacturing complexity through parameter optimization rather than structural complexity.
2Length of moving object
If the channel layer is downscaled, then device size is reduced, but leakage current increases
Solution Approach 1:
In downscaled devices, the channel layer incorporates localized oxygen-rich regions that provide superior leakage current suppression even at reduced dimensions. The non-uniform oxygen distribution ensures that critical regions maintain high oxygen concentration to prevent leakage, compensating for the size reduction effect.
Solution Approach 2:
The channel layer functions as a composite oxide semiconductor structure with varying oxygen stoichiometry. This composite approach combines regions with different oxygen concentrations to simultaneously achieve small device footprint and low leakage current, overcoming the limitations of uniform material composition in scaled devices.
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
The implementation of an oxygen-rich region in the channel layer significantly reduces leakage current, thereby enhancing the on/off characteristics and reliability of the semiconductor device.
Implementation Method 1
the channel layer comprises an oxygen-rich region in an upper portion of the channel layer, and the oxygen-rich region has an oxygen concentration greater than the oxygen concentration at a lower portion of the channel layer
Data Source
AI summary
A semiconductor device includes a bit line extending in a first horizontal direction on a substrate, a channel layer on the bit line and extending in a vertical direction, a word line adjacent to a side wall of the channel layer and extending in a second horizontal direction crossing the first horizontal direction, a gate insulating layer between the channel layer and the word line, a contact layer on an upper side of the channel layer, a capping insulating layer covering at least a portion of the contact layer, an oxygen-containing insulating layer on at least a portion of the capping insulating layer, and a capacitor including a lower electrode that contacts at least a portion of an upper surface of the contact layer.