Microscopic Pressure Sensor Thermal Time Constant Wafer Level Packaging
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Solution Overview
Problem
There is a growing need for a reliable method to measure pressure levels within MEMS systems implemented on a Wafer Level Packaging (WLP) wafer, especially after dicing, when outgassing increases pressure levels.
Innovation Solution
A pressure sensing device with a microscopic pressure sensing element having a pressure-dependent thermal parameter, which is supplied with input electrical signals to generate measurable output signals, allowing for the estimation of pressure levels within a chamber, utilizing wafer level packaging technology.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If wafer dicing is performed to create individual devices, then device packaging and deployment is enabled, but pressure level control becomes difficult due to outgassing increasing pressure within the MEMS systems
Solution Approach 1:
The patent applies preliminary action by performing pressure sensing and monitoring before the outgassing problem fully develops after dicing. The pressure sensor is integrated into the wafer during the packaging process, allowing early detection and correction of pressure changes before they affect device performance. This enables proactive pressure management rather than reactive correction.
Solution Approach 2:
The patent implements feedback by continuously monitoring pressure levels within the packaged MEMS devices and using this information to adjust packaging parameters or trigger corrective actions. The pressure sensor provides real-time data that feeds back to the control system, enabling dynamic pressure management throughout the device lifecycle, from packaging through operation.
2Measurement precision
If pressure sensing is implemented after dicing, then individual device monitoring is possible, but the complexity of integrating pressure sensing into each packaged device increases
Solution Approach 1:
The patent merges the pressure sensing function with the existing packaging structure by integrating the pressure sensor directly into the packaging process rather than adding it as a separate post-dicing step. The sensor is incorporated during wafer-level packaging, combining multiple functions (device packaging and pressure monitoring) into a unified process, thereby reducing overall system complexity despite enabling precise measurement.
Solution Approach 2:
The patent applies universality by designing a packaging solution that serves multiple functions simultaneously: it provides mechanical protection, maintains pressure control, and enables pressure monitoring. The integrated pressure sensor allows the same packaging structure to fulfill both protective and sensing roles, reducing the need for additional components and simplifying the overall device architecture.
3Productivity
If wafer level packaging is used to streamline manufacturing, then production efficiency increases, but pressure monitoring capability is lost after dicing
Solution Approach 1:
The patent applies preliminary action by establishing pressure monitoring capability during the wafer-level packaging process itself, before dicing occurs. The pressure sensor is integrated into the wafer structure during efficient bulk packaging, ensuring that pressure information is captured and monitored from the earliest possible stage, maintaining continuous awareness despite subsequent dicing and individual device deployment.
Solution Approach 2:
The patent uses an intermediary approach by incorporating a pressure sensor that acts as a mediator between the packaging process and the final individual devices. The sensor is embedded during wafer-level packaging but continues to provide pressure information for individual devices after dicing, serving as a persistent link that maintains pressure monitoring capability across the transition from bulk packaging to individual device operation.
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
Enables accurate pressure level measurement and detection, even after dicing, by leveraging the thermal time constant of the pressure sensing element, effectively addressing the challenge of increased pressure within MEMS systems.
Implementation Method 1
the pressure sensing element may be of microscopic scale (has one or more dimensions that of a magnitude of less than one hundred micron) and has a pressure level dependent thermal parameter
Implementation Method 2
a signal source that may be configured to supply an input electrical signal to the pressure sensing element
Data Source
AI summary
A pressure sensing device that includes a pressure sensing element that is of microscopic scale and has a pressure level dependent thermal parameter; a signal source that is configured to supply an input electrical signal to the pressure sensing element; and a monitor that is configured to (a) measure electrical output signals generated by the pressure sensing element as a result of the supply of the input electrical signal and (b) estimate a pressure level applied on the pressure sensing element based on the electrical output signals.