Micromechanical Bond Joint Insulation via Lateral Oxide Layer
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Solution Overview
Problem
Micromechanical components often experience parasitic resistances or capacitances due to imperfect encapsulation by casting compounds at bond pads, leading to measuring errors, especially with low currents or charges, which are difficult to eliminate.
Innovation Solution
A micromechanical component is designed with a substrate, a first oxide layer, a conductive functional layer, and a metal layer, where a second oxide layer is applied laterally to insulate the functional layer, preventing parasitic effects and allowing for improved measuring accuracy by separating the functional layer from the casting compound.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the micromechanical component is encapsulated by casting compound at bond pads, then electrical connections are established, but parasitic resistances or capacitances form between adjoining bond pads leading to measuring errors
Solution Approach 1:
The bond pad structure is segmented into multiple functional layers: a first oxide layer on the substrate, a conductive functional layer on the oxide layer, and a second oxide layer laterally on the functional layer. This segmentation isolates the functional layer from direct contact with casting compound, preventing parasitic effects while maintaining electrical connections through the metal layer for eutectic bonding.
Solution Approach 2:
The second oxide layer acts as an intermediary insulating layer between the conductive functional layer and the casting compound. This intermediary layer prevents direct contact that would cause parasitic resistances or capacitances, while still allowing the metal layer to form proper bond joints with the casting compound for electrical connections.
2Ease of manufacture
If the functional layer is directly exposed to casting compound, then bonding is simplified, but corrosion of the functional layer occurs due to impurities of the casting compound
Solution Approach 1:
The second oxide layer serves as a protective intermediary barrier between the functional layer and the casting compound. This barrier prevents corrosive impurities in the casting compound from attacking the functional layer, thereby improving durability and reliability while the metal layer continues to enable straightforward eutectic bonding processes.
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
The second oxide layer effectively prevents parasitic resistances and capacitances, enhancing measuring accuracy and reducing the risk of corrosion, while maintaining the same material for the seismic mass and functional layer, with a manufacturing process that is only slightly more complex.
Implementation Method 1
a second oxide layer, which is provided on lateral faces of the functional layer for insulating the functional layer
Implementation Method 2
The micromechanical component includes so-called bond pads for this purpose for producing a eutectic bond joint
Data Source
AI summary
A micromechanical component includes a substrate and a first oxide layer on the substrate, the first oxide layer having an aperture. The component further includes a conductive functional layer, which is provided on the first oxide layer in the region of the aperture, and a metal layer, which is provided on the functional layer, for producing a bond joint. A second oxide layer is provided on lateral faces of the functional layer for insulating the functional layer.