Phase Changeable Memory Device Thermal Insulation
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Solution Overview
Problem
Conventional phase changeable memory devices require high programming currents due to heat loss through the phase changeable layer, and the formation of undesirable oxide and fluoric layers at the interface can lead to resistor distribution failures during the etching process.
Innovation Solution
A phase changeable memory device structure where the phase changeable layer contacts the interlayer insulating layer through an insulating pattern and a lower electrode pattern, with an annular interface design that includes a spacer and insulating layers with low thermal conductivity, reducing heat loss and eliminating the need for direct contact between the phase changeable layer and the lower electrode contact.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the phase changeable layer directly contacts the lower electrode contact, then the device structure is simple, but heat loss occurs through the phase changeable layer requiring large programming current
Solution Approach 1:
An insulating layer is introduced as an intermediary between the lower electrode contact and the phase changeable layer. This insulating layer has low thermal conductivity, which blocks heat loss from the interface region while still allowing the phase changeable layer to contact the lower electrode pattern for heating. The insulating layer acts as a thermal barrier that prevents heat from conducting away through the contact region, thereby reducing the programming current required.
2Loss of energy
If an insulating layer is formed on the lower electrode pattern to reduce heat loss, then heat loss is reduced, but etching gas reacts with the lower electrode layer forming unwanted oxide and fluoric layers
Solution Approach 1:
The lower electrode pattern is formed with a specific material composition and structure before the etching process that will create the contact hole. The lower electrode pattern is designed to be resistant to etching gas reactions, or the etching process is optimized to minimize reactions with the lower electrode layer. This preliminary preparation ensures that when the contact hole is formed, unwanted oxide and fluoric layers are not created at the interface, maintaining resistor distribution reliability.
3Reliability
If the contact hole is etched wider to remove unwanted layers, then cleaning is improved, but the beneficial effects of heat reduction are decreased
Solution Approach 1:
The insulating layer is applied selectively and precisely at the critical interface regions where heat loss occurs, rather than uniformly across all surfaces. The insulating layer is positioned specifically at the lower portion and sides of the interface where the phase changeable layer contacts the lower electrode pattern. This localized application maintains the thermal barrier effect while minimizing interference with the etching process and contact hole dimensions.
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 design effectively reduces the programming current required and prevents resistor distribution failures by minimizing heat loss and eliminating unwanted oxide and fluoric layers, ensuring reliable phase changes in the memory device.
Implementation Method 1
an insulating layer having a low thermal conductivity is located at a lower portion of, and at both sides of an interface where the phase changeable layer contacts the lower electrode pattern, thereby preventing or mitigating heat loss
Implementation Method 2
When a current generated by a transistor flows through a lower electrode contact having a very small area relative to the phase changeable layer, heat is generated at the interface between the phase changeable layer and the lower electrode contact, in turn causing a phase change to occur in the phase changeable layer
Implementation Method 3
The phase changeable memory devices can perform the functions of programming and reading by changing the phase of a material layer, such as a GST (Ge2Sb2Te5) layer, between a crystalline phase and a non-crystalline phase according to the temperature of the material layer
Data Source
AI summary
In a phase changeable memory device and a method of formation thereof, the phase changeable memory device comprises: a lower electrode pattern on an interlayer insulating layer; an insulating pattern located on the lower electrode pattern; a phase changeable pattern penetrating the insulating pattern and the lower electrode pattern to contact the lower electrode pattern and the interlayer insulating layer; and an upper electrode on the phase changeable pattern.