MEMS Cap Structure with Side-Bonded Shielding Layer
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional cap structures for miniaturized MEMS devices increase package height due to the arrangement of metal cap layers and bonding wires on the upper surface, contradicting the goal of miniaturization and requiring complex micro-processing.
Innovation Solution
A cap structure with a first shield formed from the same material as the substrate, covering the electronic element, and a second shield on top, with a bonding wire connected to a metal cap layer positioned on a step between the shields, reducing the overall element height and simplifying the manufacturing process through anisotropic etching using buried and surface masks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If metal cap layer and bonding wire are arranged on the upper surface of the cap, then shielding functionality is achieved, but package height increases
Solution Approach 1:
The patent repositions the metal cap layer from the upper surface (vertical dimension) to the side surface of the cap structure, utilizing the lateral dimension instead. This dimensional shift allows the shielding function to be maintained while significantly reducing the vertical height of the package, as the bonding wire connects to the side surface rather than requiring vertical stacking.
2Length of stationary object
If conventional cap structure is used for miniaturization, then element height should be reduced, but complex micro-processing is required
Solution Approach 1:
The patent combines the formation of the metal cap layer with the existing cap structure fabrication process. Instead of adding separate complex micro-processing steps for the metal layer, it integrates the metal layer formation into the same manufacturing flow as the cap structure, using the same bonding wire connection process to achieve both structural and shielding functions simultaneously.
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 solution effectively lowers the package height and simplifies the manufacturing process, achieving miniaturization of electronic devices while maintaining shielding functionality.
Implementation Method 1
anisotropic etching is performed. An anisotropic etching solution is used to process the silicon material. In this embodiment, tetramethyl -ammonium-hydroxide (TMAH) is used for etching. In a silicon crystal, a [111] face is only slightly etched by TMAH but the [100] face is etched at a rate of approximately 9000 μm/min.
Data Source
AI summary
An electronic device including a shielded electronic element, and a method for manufacturing a shielding structure. An oxide film is formed on the surface of a silicon substrate having a [100] face. Part of the oxide film is removed to form a first window region. Silicon substrates are joined together to form an SOI substrate, which includes a buried mask having a second window region. Substrate thinning is then performed, and oxide films are formed on the two surfaces of the SOI substrate so that the first window region has a large area and includes the region above the buried second window region. Then, anisotropic etching is performed to form a cap that includes a step. Wire bonding for shielding is performed on the step.