Magnetoresistive Device Alignment via Selective Etching and Deposition Tabs
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Solution Overview
Problem
In the manufacturing of magnetoresistive devices, such as magnetic random access memory (MRAM), alignment marks are often obscured by deposited layers, leading to challenges in precise etching and potential degradation of magnetic layers due to oxidation, which can result in device performance issues and unwanted electrical connections.
Innovation Solution
The use of selective etching techniques to expose alignment marks and the implementation of deposition tool tabs to prevent the obscuration of these marks during layer deposition, ensuring their visibility for precise alignment and patterning of magnetoresistive devices, along with encapsulation to protect the magnetic layers from corrosive atmospheres.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If layers of material are deposited during magnetoresistive device manufacturing, then device structure is formed, but alignment marks become obscured
Solution Approach 1:
The patent segments the manufacturing process into distinct phases: a first etching operation exposes alignment marks before deposition, then a second etching operation occurs after deposition. This segmentation allows alignment marks to be visible when needed for alignment while being covered during deposition to protect underlying structures.
Solution Approach 2:
The alignment marks are exposed and used for alignment purposes before the deposition of material layers occurs. This preliminary action ensures that subsequent deposition and etching operations can be precisely aligned with the magnetoresistive stack, while the marks remain protected during the deposition phase.
2Productivity
If etching operations are performed to pattern magnetoresistive devices, then device density increases, but alignment precision deteriorates due to obscured marks
Solution Approach 1:
The etching process is divided into two separate operations: a first etching that exposes alignment marks to enable precise alignment, and a second etching that patterns the magnetoresistive devices. This segmentation ensures that alignment precision is maintained while achieving high device density through subsequent patterning.
Solution Approach 2:
The first etching operation performs the preliminary action of exposing alignment marks before the main device patterning etch. This allows the alignment marks to guide the second etching operation with high precision, ensuring accurate device placement and orientation even at high densities.
3Adaptability or versatility
If magnetic layers are exposed during processing, then patterning flexibility improves, but oxidation and degradation occur
Solution Approach 1:
The alignment marks are exposed and used for alignment before the deposition of protective material layers occurs. This preliminary exposure allows flexible alignment operations while the subsequent deposition provides protection against oxidation and degradation during storage and further processing.
Solution Approach 2:
The patent introduces deposited material layers as an intermediary protective barrier between the magnetic layers and the corrosive atmosphere. These layers are deposited after alignment mark exposure, providing protection against oxidation while allowing the alignment marks to have been previously exposed for patterning flexibility.
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 allows for accurate alignment and formation of magnetoresistive devices, minimizing device variance and preventing oxidation-related degradation, thereby enhancing device density and performance by maintaining alignment mark visibility and protecting the magnetic layers.
Implementation Method 1
a deposition tool tab is positioned based on a location of the alignment marks on the substrate such that during deposition of a plurality of layers, the deposition tool tab selectively prevents deposition of material corresponding to at least a portion of the plurality of layers in a region corresponding to the alignment marks
Implementation Method 2
a patterned layer of photoresist is formed over the plurality of layers, and the patterned layer of photoresist is used to etch the plurality of layers and form the magnetoresistive devices
Implementation Method 3
encapsulation to protect the magnetic layers from corrosive atmospheres
Data Source
AI summary
Techniques are presented for ensuring alignment marks are available for use and patterning magnetoresistive devices following the deposition of layers used to form the magnetoresistive devices. In some cases, the plurality of layers corresponding to the magnetoresistive devices are selectively etched in order to expose the underlying alignment marks, whereas in other embodiments, the deposition of the plurality of layers is controlled by deposition tool tabs that prevent the materials from obscuring the underlying alignment marks.