Variable Resistance Element Resistivity Control via Sputtering Power
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Solution Overview
Problem
The existing methods for forming metal oxide layers in variable resistance elements, such as ReRAM, face challenges in controlling resistivity due to large changes with oxygen flow rates and adsorption issues, leading to difficulty in achieving precise resistivity distribution across wafers.
Innovation Solution
A method involving the formation of first and second metal oxide layers with different resistivities using sputtering targets with distinct powers, where the second target's power is varied to control oxidation degrees, allowing for precise resistivity control without altering the first target's power, and using a noble gas to suppress plasma formation influences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If reactive sputtering is used to form metal oxide layers by controlling oxygen flow rate, then metal oxide layers with different oxidation degrees can be formed, but the resistivity control precision deteriorates due to large changes in resistivity with respect to oxygen flow rate and adsorption of oxygen on target surface
Solution Approach 1:
The patent changes the controlling parameter from oxygen flow rate to radio frequency power. By adjusting the RF power supplied to the metal target during sputtering, the oxidation degree and resistivity of metal oxide layers can be precisely controlled. This parameter change eliminates the problems of large resistivity variations and surface adsorption effects associated with oxygen flow rate control.
2Manufacturing precision
If oxygen flow rate is adjusted to control oxidation degree, then different resistivities can be achieved, but uniformity across wafers deteriorates due to resistivity distribution in wafer plane and between wafers
Solution Approach 1:
The patent replaces oxygen flow rate control with RF power control to achieve uniform oxidation across wafers. By controlling the radio frequency power supplied to the target, the oxidation degree becomes uniform across the wafer plane and consistent between wafers, eliminating the distribution problems associated with oxygen flow rate method.
3Ease of manufacture
If metal target is sputtered in oxygen atmosphere to form metal oxide, then variable resistance element structure can be formed, but manufacturing complexity increases due to difficulty in achieving desired resistivity with high precision
Solution Approach 1:
The patent maintains the reactive sputtering process feasibility while improving resistivity precision by changing the control parameter from oxygen flow rate to RF power. This allows the manufacturing process to remain practical while achieving high precision resistivity control for variable resistance elements.
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 enables the formation of metal oxide layers with desired resistivities, achieving high precision and uniformity across wafers, thereby stabilizing the manufacturing of variable resistance elements with intended electric properties.
Implementation Method 1
The first metal oxide layer is formed on a substrate by sputtering, while sputtering a first target made of an oxide of metal
Implementation Method 2
The second metal oxide layer is formed on the first metal oxide layer by sputtering the second target with a second power different from the first power while sputtering the first target
Data Source
AI summary
[Object] To provide a method and an apparatus for manufacturing a variable resistance element by which a metal oxide layer having a desired resistivity can be precisely formed.[Solving Means] The method of manufacturing the variable resistance element according to an embodiment of the present invention includes a step of forming a first metal oxide having a first resistivity and a step of forming a second metal oxide having a second resistivity different from the first resistivity. The first metal oxide is formed on a substrate by sputtering, while sputtering a first target made of an oxide of metal, a second target made of the metal with a first power. The second metal oxide layer is formed on the first metal oxide layer by sputtering the second target with a second power different from the first power while sputtering the first target.