Etch-Resistant Protective Coating for Magnetic Tunnel Junction Spacers
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Solution Overview
Problem
The existing methods for forming magnetic tunnel junction (MTJ) devices face issues with spacers wearing down during etching processes, leading to redeposition material forming shunt paths and causing poor device performance or inoperability due to lack of etch resistance.
Innovation Solution
A method involving the formation of an etch-resistant protective coating, such as a protective crown, on the spacer to prevent wear and redeposition material from reaching sensitive layers, using directional deposition and oxidation processes to enhance etch resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a spacer is used to protect the MTJ device from redeposition material during etching, then the device is protected from shunt paths, but the spacer itself wears down during the etching process
Solution Approach 1:
The patent applies composite materials by combining the spacer (made of silicon nitride or silicon oxide) with an etch-resistant protective coating (such as tantalum, tungsten, or platinum). This composite structure allows the spacer to maintain its protective function while the coating provides the necessary etch resistance during the etching process, preventing the spacer from wearing down and forming shunt paths.
2Object-affected harmful factors
If the spacer material is chosen for its protective properties, then it effectively blocks redeposition material, but it lacks sufficient etch resistance to withstand the etching process
Solution Approach 1:
The etch-resistant protective coating serves as an intermediary between the spacer and the etching environment. The coating material (tantalum, tungsten, or platinum) is specifically chosen to be resistant to the etching chemicals, allowing the spacer to perform its protective function of blocking redeposition material without being degraded by the etching process itself.
3Ease of manufacture
If no protective coating is applied to the spacer, then the manufacturing process is simpler, but redeposition material forms shunt paths causing device failure
Solution Approach 1:
The etch-resistant protective coating is applied to the spacer before the etching process begins. This preliminary action ensures that when the etching process occurs, the spacer is already protected and will not wear down to form shunt paths. The coating is deposited using physical vapor deposition (PVD) or chemical vapor deposition (CVD) methods, and may be further protected by forming a crown structure or applying additional protective layers.
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 protects the spacer from wear during etching, reducing the formation of shunt paths and improving the manufacturing yield of MTJ devices by preventing redeposition material from contacting critical layers, thus enhancing device performance.
Implementation Method 1
forming an etch-resistant protective coating associated with the MTJ device, the etch-resistant protective coating providing greater etch resistance to a subsequent etching process than the spacer
Implementation Method 2
The spacer protects the MTJ device from redeposition byproduct resulting from subsequent etching during formation of other portions of the MTJ device
Data Source
Figure 1A~1C
Figure 2A~2D
Figure 3A~3D
AI summary
A method of forming a magnetic tunnel junction (MTJ) device (118) includes forming a spacer (116) on an exposed side portion of the MTJ device (124). The method further includes forming an etch-resistant protective coating (116) associated with the MTJ device (118). The etch-resistant protective coating (130) provides greater etch resistance than the spacer (116).