MEMS-CMOS Metal Conductor Interconnection via Plasma Etching Protection
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Solution Overview
Problem
Conventional MEMS and IC technologies face challenges in increasing performance, reducing size, and decreasing cost, particularly in forming effective electrical interconnections and protecting against damage during plasma etching processes.
Innovation Solution
A method and structure for adapting MEMS structures to form electrical interconnections with CMOS integrated circuits by etching specific portions of metal conductors, forming protective circuits, and using conductive jumpers to couple the metal conductor to the substrate, while employing conductive shielding and silicon walls to prevent damage from plasma etching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional plasma etching process is used for MEMS fabrication, then MEMS structures can be formed, but metal conductors in CMOS devices are damaged or defective due to charge build-up antenna effect
Solution Approach 1:
The patent applies preliminary action by removing portions of the metal conductor before the plasma etching process. Specifically, first and second portions of the metal conductor are removed prior to forming the MEMS layer, which prevents plasma damage and charge build-up during the subsequent plasma etching process. This advance modification eliminates the harmful effect before it can occur.
Solution Approach 2:
The patent applies the taking out principle by extracting (removing) specific portions of the metal conductor that would be damaged by plasma. The first portion directly subjected to plasma and the second portion indirectly subjected to plasma are both removed, leaving only the third portion that remains protected. This extraction eliminates the vulnerability to plasma damage.
2Object-affected harmful factors
If metal conductor is completely removed to prevent plasma damage, then protection from plasma is achieved, but electrical interconnection between CMOS device and substrate is lost
Solution Approach 1:
The patent applies segmentation by dividing the metal conductor into distinct portions: a first portion removed to prevent plasma damage, a second portion removed for additional protection, and a third portion retained to maintain electrical interconnection. This segmentation allows selective removal of vulnerable sections while preserving the conductive path needed for electrical connectivity.
Solution Approach 2:
The patent applies local quality by applying different treatments to different portions of the metal conductor. The first and second portions are removed (no metal present), while the third portion is preserved (metal present). This localized differentiation allows the structure to simultaneously achieve plasma protection in exposed areas and electrical connectivity in protected areas.
3Adaptability or versatility
If MEMS layer is formed overlying metal conductor, then integrated CMOS-MEMS device is created, but charge build-up antenna effect damages the metal conductor during plasma etching
Solution Approach 1:
The patent applies preliminary action by removing portions of the metal conductor before forming the MEMS layer and before performing plasma etching. This advance removal prevents the charge build-up antenna effect from developing during the plasma etching process, while still allowing the MEMS layer to be formed over the modified structure and achieve integrated CMOS-MEMS functionality.
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 enhances device yields, protects against defects, and improves the integration of MEMS and CMOS systems, enabling higher performance and manufacturability without requiring substantial modifications to conventional equipment or processes.
Implementation Method 1
A first portion and a second portion of the metal conductor that would be directly or indirectly subjected to plasma during a plasma etching process of a MEMS layer are removed by performing an etching process
Data Source
AI summary
Methods and structure for adapting MEMS structures to form electrical interconnections for integrated circuits. A first portion and a second portion of the metal conductor, which can be electrically isolated within a CMOS IC device, can be etched to form an unetched portion of the metal conductor. The MEMS device can be patterned, from a MEMS layer formed overlying the metal conductor, via a plasma etching process, during which the unetched portion of the metal conductor is protected from the plasma. The metal conductor can be electrically coupled to the CMOS IC device via a conductive jumper or the like. Furthermore, the integrated CMOS-MEMS device can include a MEMS device coupled to a CMOS IC device via an electrically isolated metal conductor within the CMOS IC device. Also, the metal conductor can be electrically coupled to the substrate of the CMOS IC device via a conductive jumper.