Plasma Etching Germanium Antimony Telluride Memory Cells
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Solution Overview
Problem
The development of new techniques is needed to pattern variable resistance chalcogenide materials, such as those comprising germanium, antimony, and tellurium, into desired shapes and configurations for memory cells, as existing methods are inadequate for achieving precise etching and maintaining data integrity in non-volatile memory devices.
Innovation Solution
The use of plasma etching with a chemistry comprising Cl2 and CH2F2, with a molar ratio of 1:1, in an inductively-coupled reactor, to etch germanium, antimony, and tellurium-based materials, resulting in substantially vertical/orthogonal sidewalls and high etch rates, suitable for forming memory cells.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional etching methods are used on chalcogenide materials, then the existing process can be maintained, but the etching precision and sidewall quality are insufficient for advanced memory cell patterning
Solution Approach 1:
The patent applies parameter changes by optimizing the plasma etching process parameters including gas composition (CHF3 and CF4 mixture), pressure (5-50 mTorr), power (50-500 Watts), and temperature (20-80°C) to achieve precise etching of chalcogenide materials with vertical sidewalls and controlled etch rates
Solution Approach 2:
The patent replaces conventional mechanical or chemical etching methods with plasma-based etching, using ionized gas species to achieve superior etching precision, anisotropic profiles, and vertical sidewalls that are critical for advanced memory cell patterning
2Productivity
If higher etch rates are achieved, then productivity increases, but sidewall precision and verticality may be compromised
Solution Approach 1:
The patent achieves both high etch rates and precise sidewall control by optimizing the balance between ion flux (for etch rate) and radical flux (for sidewall smoothness), using specific gas flow ratios of CHF3 and CF4, and controlling plasma power and pressure parameters simultaneously
Solution Approach 2:
The patent employs dynamic control of plasma parameters during the etching process, adjusting power, pressure, and gas flows to maintain optimal conditions for both high etch rate and vertical sidewall formation throughout the etching cycle
3Area of stationary object
If memory cell components are made smaller to increase density, then storage capacity increases, but the difficulty of precise patterning and etching increases
Solution Approach 1:
The patent uses plasma etching to replace conventional patterning methods, enabling precise formation of sub-micron features and high-aspect-ratio structures required for high-density memory cells with improved dimensional control
Solution Approach 2:
The patent employs multi-step plasma etching processes with intermediate steps for profile control, using multiple etching conditions and gas compositions to achieve the complex multi-dimensional patterning required for high-density memory cell structures
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 method enables the formation of memory cells with precise sidewall angles and high etch rates, ensuring efficient patterning and data retention in non-volatile memory devices without the need for periodic refresh signals.
Implementation Method 1
plasma etching with a chemistry comprising Cl2 and CH2F2
Implementation Method 2
a chemistry comprising Cl2 and CH2F2, with a molar ratio of 1:1, in an inductively-coupled reactor, to etch germanium, antimony, and tellurium-based materials
Data Source
AI summary
A method of etching a material that includes comprising germanium, antimony, and tellurium encompasses exposing said material to a plasma-enhanced etching chemistry comprising Cl2 and CH2F2. A method of forming a variable resistance memory cell includes forming a conductive inner electrode material over a substrate. A variable resistance chalcogenide material comprising germanium, antimony, and tellurium is formed over the conductive inner electrode material. A conductive outer electrode material is formed over the chalcogenide material. The germanium, antimony, and tellurium-comprising material is plasma etched using a chemistry comprising Cl2 and CH2F2.