MgO Tunnel Layer Oxygen Exposure for MRAM TMR Recovery
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Solution Overview
Problem
Semiconductor manufacturing processes, particularly in MRAM devices, face a significant decrease in tunnel magnetoresistance (TMR) values after periodic maintenance of physical vapor deposition chambers, leading to nonuniformities and defects in production.
Innovation Solution
The method involves forming magnesium oxide (MgO) layers using radio frequency (RF) power and exposing them to oxygen to enhance TMR values, with specific exposure times and flow rates, and applying these treatments after chamber maintenance to restore pre-maintenance TMR levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If chamber maintenance is performed every 2-10 thousand wafers, then process kits and sputtering targets are replaced, but TMR values decrease significantly after maintenance
Solution Approach 1:
The patent introduces oxygen plasma as an intermediary treatment between chamber maintenance and normal production. This intermediary step addresses the oxygen depletion in the MgO tunnel layer caused by maintenance activities. The oxygen plasma exposure (at approximately 10-15 sccm flow rate for 5-20 seconds) acts as a mediator that restores the chemical composition of the MgO layer, enabling high TMR values to be achieved rapidly without requiring extensive burn-in production, thus maintaining both productivity and TMR consistency.
2Ease of manufacture
If MgO layer is formed by sputtering with RF power, then tunnel barrier is deposited, but oxygen deficiency occurs leading to low TMR values
Solution Approach 1:
The patent applies strong oxidants by using oxygen plasma treatment on the MgO tunnel layer after sputter deposition. The oxygen plasma provides a high concentration of reactive oxygen species that rapidly reoxidize the MgO layer, compensating for the oxygen deficiency inherent in the sputtering process. This accelerated oxidation restores the stoichiometry and crystal structure of the MgO tunnel barrier, enabling high TMR values (at least 150%) to be achieved within 0.5 kwh of burn-in, without requiring lengthy conventional burn-in procedures.
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 effectively recovers and maintains high TMR values, reducing defects and production delays by addressing oxygen deficiencies caused by maintenance procedures, achieving TMR values of at least 150% within 0.5 kwh of process chamber burn-in.
Implementation Method 1
forming a first magnesium oxide (MgO) layer by sputtering an MgO target using radio frequency (RF) power
Implementation Method 2
sputtering an MgO target using radio frequency (RF) power
Implementation Method 3
exposing the first MgO layer to oxygen
Implementation Method 4
exposing the first MgO layer to oxygen for approximately 5 seconds to approximately 20 seconds
Data Source
AI summary
A method of forming a tunnel layer of a magnetoresistive random-access memory (MRAM) structure includes forming a first magnesium oxide (MgO) layer by sputtering an MgO target using radio frequency (RF) power, exposing the first MgO layer to oxygen for approximately 5 seconds to approximately 20 seconds at a flow rate of approximately 10 sccm to approximately 15 sccm, and forming a second MgO layer on the first MgO layer by sputtering the MgO target using RF power. The method may be performed after periodic maintenance of a process chamber to increase the tunnel magnetoresistance (TMR) of the tunnel layer.