Variable Resistance Element Sidewall Spacer Design
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Solution Overview
Problem
Existing semiconductor memory devices face challenges in maintaining the desired characteristics of variable resistance elements, particularly in terms of magnetic anisotropy and resistance switching, due to issues with sidewall spacers and oxidation processes that can lead to leakage current and deterioration of operation characteristics.
Innovation Solution
The implementation of a semiconductor memory device with a Magnetic Tunnel Junction (MTJ) structure incorporating a sidewall spacer made of low-temperature amorphous silicon, which provides compressive stress and blocks boron out-diffusion, along with additional spacers of metal oxides and silicon-containing materials, to enhance boron content and improve magnetic anisotropy and resistance switching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional sidewall spacers are used in variable resistance elements, then the structure is simpler, but magnetic anisotropy and resistance switching characteristics deteriorate
Solution Approach 1:
The sidewall spacer is divided into multiple distinct layers: a first sidewall spacer layer (Ta or TaN) and a second sidewall spacer layer (W). This segmentation allows each layer to perform specific functions - the Ta/TaN layer provides oxidation resistance and structural support, while the W layer contributes to magnetic anisotropy through compressive stress, thereby improving overall device reliability without requiring a completely new structure
Solution Approach 2:
The sidewall spacer employs a composite structure combining different materials (Ta/TaN and W) with complementary properties. The Ta/TaN material provides oxidation resistance and structural stability, while the W material provides compressive stress for perpendicular magnetic anisotropy. This composite approach enables simultaneous achievement of structural integrity and magnetic performance
2Stability of the object's composition
If oxidation processes are applied to sidewall spacers, then structural stability improves, but leakage current increases and operation characteristics deteriorate
Solution Approach 1:
The first sidewall spacer layer is formed from Ta or TaN materials that are inherently resistant to oxidation. This creates an inert-like protective environment around the variable resistance element, preventing oxygen from reaching and oxidizing the magnetic layers. The oxidation-resistant material maintains structural stability while preventing the harmful oxidation effects that cause leakage current and performance degradation
3Reliability
If boron doping is applied to amorphous silicon sidewall spacers, then magnetic anisotropy improves, but boron out-diffusion occurs leading to characteristic deterioration
Solution Approach 1:
The patent introduces an intermediary barrier layer between the boron-doped amorphous silicon sidewall spacer and the variable resistance element. This intermediate layer prevents direct contact and boron out-diffusion while still allowing the compressed silicon structure to provide the necessary compressive stress for perpendicular magnetic anisotropy. The intermediary protects the magnetic layers from boron contamination while maintaining the beneficial mechanical stress
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 configuration enhances the thermal stability and operational characteristics of the variable resistance element, improving the magnetic anisotropy and resistance switching performance while preventing deterioration, thereby improving the overall performance of the semiconductor memory device.
Implementation Method 1
a sidewall spacer disposed on a sidewall of the variable resistance element and including an amorphous silicon
Implementation Method 2
The amorphous silicon may be a low temperature amorphous silicon which is deposited at a temperature from 150° C. to 400° C.
Implementation Method 3
each variable resistance element may include a Magnetic Tunnel Junction (MTJ) structure including a free layer having a changeable magnetization direction, a pinned layer having a fixed magnetization direction and a tunnel barrier layer interposed between the free layer and the pinned layer
Data Source
AI summary
An electronic device is provided to include a semiconductor memory which includes one or more variable resistance elements, wherein each variable resistance element may include a Magnetic Tunnel Junction (MTJ) structure including a free layer having a changeable magnetization direction, a pinned layer having a fixed magnetization direction and a tunnel barrier layer interposed between the free layer and the pinned layer; and a sidewall spacer disposed on a sidewall of the variable resistance element and including an amorphous silicon.