MEMS Sensor Polymer Coating for Dicing Damage Prevention
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Solution Overview
Problem
Microelectromechanical system (MEMS) sensor devices without protective cavities are vulnerable to damage during the dicing process due to exposure to water and debris, leading to potential cracking and fracture, which can be difficult to detect and may result in loss of hermeticity and functional failure.
Innovation Solution
Applying a polymer coating, such as a photoresist material, to protect fragile sensor components during the dicing process, which acts as a buffer against water and debris, and can be patterned to avoid coverage of scribe lines and bond pads, and optionally removed after dicing to expose the sensor structures to the ambient environment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If MEMS sensor devices are designed without protective cavities to enable interaction with the surrounding environment, then the sensors can accurately measure ambient conditions, but the fragile structures become vulnerable to damage during dicing from water and debris
Solution Approach 1:
A protective coating is applied to the MEMS sensor structures before the dicing process. This preliminary protective action shields the fragile diaphragms and moving structures from water impingement and debris during subsequent fabrication steps, preventing cracking while allowing the structures to remain unsealed for environmental interaction.
Solution Approach 2:
The protective coating acts as an intermediary layer between the fragile MEMS structures and the harmful dicing environment (water and debris). This intermediate protective layer absorbs the mechanical stress and physical impact during dicing, allowing the sensor to maintain both structural integrity and environmental accessibility.
2Productivity
If water is used to cool the saw blade and clean the wafer during dicing, then the dicing process can proceed efficiently, but the water may impinge upon and damage the fragile sensor structures
Solution Approach 1:
The protective coating serves as an intermediary barrier that allows water to be used for cooling and cleaning during dicing while preventing the water from directly contacting and damaging the fragile MEMS structures. This enables efficient dicing operations without compromising sensor integrity.
Solution Approach 2:
A thin flexible protective coating is applied over the MEMS structures, providing sufficient mechanical protection against water impingement and debris during the dicing process while being thin enough to allow subsequent environmental interaction when the coating is removed or designed to be permeable.
3Reliability
If the polymer coating is applied to protect sensor structures during dicing, then cracking and fracture are reduced, but additional fabrication steps and material removal are required
Solution Approach 1:
The protective polymer coating is applied during fabrication to protect sensor structures, then systematically removed after serving its protective purpose. This temporary protective measure is discarded once the dicing process is complete, avoiding permanent complexity while providing necessary protection during critical fabrication steps.
Solution Approach 2:
The protective coating material is selected and applied with specific parameters (thickness, material properties) that optimize protection during dicing while minimizing the complexity of subsequent removal. By carefully controlling the coating parameters, the protective function is maximized while the additional fabrication steps remain manageable.
Data Source
AI summary
A microelectromechanical system (MEMS) sensor device includes a substrate, a support structure supported by the substrate, a membrane supported by the support structure and spaced from the substrate, and a polymer layer covering the membrane.