MEMS Cavity Pressure Control via Polymer Degradation
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Solution Overview
Problem
Existing MEMS devices face challenges in forming reliable structures, particularly in achieving consistent pressure environments within their cavities, which affects their performance and reliability.
Innovation Solution
A method involving a semiconductor substrate and a MEMS layer bonded with a cap layer, where a polymer material is used to form gas in a cavity, increasing the pressure within the cavity from a vacuum level to a higher pressure, using thermal or light degradation of the polymer element to control the gas production and pressure accurately.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional vacuum sealing methods are used to form cavities, then hermetic sealing is achieved, but the process complexity and manufacturing cost increase
Solution Approach 1:
The patent changes the pressure parameter within the cavity from vacuum to positive pressure by introducing gas through polymer degradation. This parameter change eliminates the need for complex vacuum sealing processes while maintaining hermetic sealing reliability, as the positive pressure environment is more tolerant to manufacturing variations and does not require sophisticated vacuum pumps or seals
Solution Approach 2:
The patent uses a polymer element that degrades to produce gas, replacing expensive and complex vacuum pumping systems. The polymer is a simple, low-cost material that performs the function of pressure control through its degradation process, eliminating the need for expensive vacuum maintenance equipment and complex sealing mechanisms
2Ease of manufacture
If polymer material is used to form gas in cavity, then pressure control is simplified and cost reduced, but precise pressure level achievement becomes challenging
Solution Approach 1:
The patent incorporates pressure sensors that monitor the cavity pressure and provide feedback to a control system. Based on this feedback, the system adjusts the degradation process of the polymer element to achieve and maintain the desired pressure level, ensuring manufacturing precision while maintaining ease of manufacture
Solution Approach 2:
The patent controls the degradation rate and extent of the polymer element by adjusting parameters such as temperature, light exposure, or chemical catalysts. By changing these parameters, the system can precisely control the amount of gas produced and thus the final pressure level in the cavity, achieving both ease of manufacture and manufacturing precision
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 the creation of hermetically sealed cavities with controlled pressure levels, enhancing the reliability and performance of MEMS devices by using a cost-effective and easily controllable polymer-based method to achieve high pressure levels within the MEMS device structure.
Implementation Method 1
degrading the polymer element to form a gas in the first cavity to increase the first pressure of the first cavity from a first pressure level to a second pressure level which is higher than the first pressure level
Implementation Method 2
using thermal or light degradation of the polymer element to control the gas production and pressure accurately
Data Source
AI summary
Structures and formation methods of a MEMS device structure are provided. The MEMS device structure includes a semiconductor substrate having a first region and a second region, and a MEMS layer over the semiconductor substrate. The MEMS layer has a first through hole positioned in the first region and a second through hole positioned in the second region. The MEMS device structure also includes a cap layer over the MEMS layer, a first cavity between the semiconductor substrate and the cap layer and in the first region, and a second cavity between the semiconductor substrate and the cap layer and in the second region. The MEMS device structure further includes a carbon-based degradation product in the first cavity.