Electroless Nickel Cobalt Plating for MEMS Yield Point
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Solution Overview
Problem
MEMS devices using electroplated nickel or cobalt suffer from low yield point and creep deformation, leading to early fatigue and increased fabrication complexity, and silicon-based devices have suboptimal electrical properties and thermal expansion coefficients.
Innovation Solution
Electroless plating of nickel or cobalt alloys with phosphorus or boron, forming amorphous structures with higher yield points and thermal expansion, reducing creep deformation and fabrication complexity, while maintaining desirable mechanical and electrical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If electroplated nickel or cobalt is used for structural elements, then electrical conductivity is improved, but yield point and creep resistance deteriorate
Solution Approach 1:
The patent uses composite material structures by combining electroless-plated nickel or cobalt with underlying sacrificial layers (such as silicon oxide or silicon nitride). The electroless-plated metal layer provides electrical conductivity and structural function, while the sacrificial layer provides mechanical support and prevents direct contact between the metal and substrate, thereby improving yield point and creep resistance while maintaining electrical conductivity.
2Use of energy by moving object
If electroplating process is used, then electrical conductivity is improved, but fabrication complexity increases
Solution Approach 1:
The patent extracts the problematic electroplating step from the fabrication process and replaces it with electroless plating. By removing the need for complex electroplating equipment and process control, the fabrication complexity is reduced while still achieving the desired electrical conductivity and structural properties in the MEMS device.
Solution Approach 2:
The patent replaces the electroplating process (which requires electrical fields and complex equipment) with electroless plating (which uses chemical reactions). This substitution eliminates the need for complex electroplating machinery and process control systems, thereby reducing fabrication complexity while maintaining the ability to produce conductive metal structures.
3Strength
If high temperature processing is used for silicon fabrication, then mechanical strength is improved, but thermal damage to temperature-sensitive components occurs
Solution Approach 1:
The patent changes the processing temperature parameter by using electroless plating, which can be performed at lower temperatures compared to traditional silicon fabrication processes. This parameter change allows the formation of metal structures without subjecting temperature-sensitive components to high thermal stress, thereby preventing thermal damage while still achieving the desired mechanical strength through the electroless-plated metal layer.
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 electroless nickel or cobalt plated structures exhibit improved yield points and thermal expansion, enabling reliable and precise movement of MEMS components with reduced fatigue and lower fabrication costs, while avoiding thermal damage to temperature-sensitive components.
Implementation Method 1
forming a structural element on a surface of a layer via an electroless plating of nickel or cobalt onto the surface
Implementation Method 2
The structural element includes electrolessly plated nickel or cobalt alloyed with phosphorus or boron. The applied current causes the second part to move.
Data Source
AI summary
A method comprising forming a structural element 115 on a surface 620 of a layer 510 via an electroless plating of nickel or cobalt 130 onto the surface, the layer being rigidly fixed to an underlying substrate 110. The method also comprises etching away a portion of the layer such that a part of the structural element is able to move with respect to the substrate.