Composite Sputter Target for Doped Phase Change Materials
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Solution Overview
Problem
The manufacturing of doped chalcogenide memory devices faces challenges with yield, endurance, and data retention due to contamination from particles produced in co-sputtering and compound target processes, especially when using dielectric additives like silicon oxides and silicon nitrides.
Innovation Solution
A method involving a composite sputter target with a phase change material and a semiconductor additive, where the semiconductor concentration is greater than five times the desired concentration in the layer, allowing for the formation of layers with controlled silicon or silicon-based additives using reactive gases like oxygen or nitrogen, enabling the creation of multilayer structures without particle contamination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If co-sputtering using silicon oxide target and chalcogenide target is used, then dielectric additives can be incorporated into phase change materials, but particle contamination occurs on wafer surface reducing yield
Solution Approach 1:
The invention separates the dielectric additive incorporation from the phase change material deposition by using a single-element silicon target with reactive gas, rather than co-sputtering silicon oxide and chalcogenide targets together. This segmentation eliminates particle contamination while achieving the desired doping effect.
Solution Approach 2:
The invention introduces reactive gas (oxygen or nitrogen) as an intermediary that reacts with silicon atoms during sputtering to form silicon oxide or silicon nitride in-situ. This mediator approach avoids direct use of silicon oxide target material that would generate particles, achieving dielectric doping without contamination.
2Manufacturing precision
If compound target process is used for dielectric additives, then doping can be achieved, but particle contamination reduces manufacturing yield
Solution Approach 1:
The invention changes the fundamental parameter of target composition from compound (silicon oxide) to elemental (silicon), and controls the doping concentration through reactive gas flow rate and sputtering conditions. This parameter change eliminates particle generation while maintaining precise doping control.
3Manufacturing precision
If higher semiconductor concentration in target is used (greater than five times desired concentration), then effective doping can be achieved, but target material consumption increases
Solution Approach 1:
The invention uses excessive semiconductor concentration in the target (greater than five times the desired concentration in the layer) to ensure effective doping. The high concentration compensates for material loss during sputtering and allows precise control of the final doping level through process parameters rather than target composition alone.
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 improves yield and endurance while maintaining data retention, as it forms layers with effective silicon or silicon-based additives without particle contamination, enhancing the reliability and cost-effectiveness of the manufacturing process.
Implementation Method 1
A method for forming a layer of phase change material with a silicon or other semiconductor, or a silicon-based or other semiconductor-based additive, is described based on the use of a composite sputter target
Implementation Method 2
For silicon-based additive in GST type phase change materials, sputter target may comprise more than 30 atomic percent (at %) silicon and preferably between 40 and 60 at % silicon
Implementation Method 3
allowing for the formation of layers with controlled silicon or silicon-based additives using reactive gases like oxygen or nitrogen
Data Source
AI summary
A layer of phase change material with silicon or another semiconductor, or a silicon-based or other semiconductor-based additive, is formed using a composite sputter target including the silicon or other semiconductor, and the phase change material. The concentration of silicon or other semiconductor is more than five times greater than the specified concentration of silicon or other semiconductor in the layer being formed. For silicon-based additive in GST-type phase change materials, sputter target may comprise more than 40 at % silicon. Silicon-based or other semiconductor-based additives can be formed using the composite sputter target with a flow of reactive gases, such as oxygen or nitrogen, in the sputter chamber during the deposition.