Inertial Sensor Package Sealing to Prevent Laser Splash Contamination
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Solution Overview
Problem
Existing methods for sealing MEMS packages using laser-emitted laser light to adjust air pressure in a cavity can contaminate the sensor due to splashes, leading to reduced reliability and yield.
Innovation Solution
An inertial sensor design with a base body, lid body, and electrostatic capacitance element, sealed by a sealer formed from melted lid body material using laser light to prevent contamination and ensure hermetic sealing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a hole is opened in the cap wafer to adjust air pressure in the cavity, then the air pressure can be adjusted, but the sensor may be contaminated by splashes generated from the cap wafer due to laser light emission
Solution Approach 1:
The patent applies preliminary action by forming the sealer structure (protrusion or recess) before the laser light emission process. This pre-formed structure ensures that when the laser is emitted to close the hole, the melted material is directed into the sealer rather than splashing onto the sensor, thus preventing contamination before it can occur
Solution Approach 2:
The patent introduces a sealer as an intermediary structure between the hole and the sensor. This sealer, formed by melted material from the cap wafer or base body, acts as a mediator that receives the laser processing energy and redirects it away from the sensor, preventing direct contamination while still allowing the hole to be sealed
2Ease of manufacture
If laser light is emitted to melt the cap wafer around the hole to close it, then the hole is sealed, but the sensor reliability is reduced due to contamination
Solution Approach 1:
The sealer structure serves as an intermediary that captures the laser processing effect and directs the melted material away from the sensor. This allows the sealing process to proceed effectively while protecting the sensor from contamination
Solution Approach 2:
The patent extracts the harmful effect (splash contamination) from the sealing process by introducing a dedicated sealer structure. The sealer absorbs the laser energy and directs the melted material into itself rather than allowing it to reach the sensor, thus separating the sealing function from the contamination risk
3Productivity
If the hole is sealed by melting the cap wafer material, then the cavity is sealed, but contamination occurs affecting yield
Solution Approach 1:
The sealer structure is prepared in advance before the sealing operation. This preliminary configuration ensures that when the laser is emitted, the melted material has a predetermined path into the sealer, preventing contamination and ensuring high yield
Solution Approach 2:
The sealer acts as an intermediary structure that captures the laser processing effects and redirects them away from the sensor. This mediator structure ensures that the sealing process completes successfully without contaminating the sensor, thereby maintaining high manufacturing yield
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
Prevents sensor contamination, maintains reliability, and extends the lifespan of inertial sensors by preventing moisture ingress and maintaining a stable internal environment.
Implementation Method 1
an adhesive layer provided in a peripheral region surrounding the space and configured to adhere the base body and the lid body to each other
Implementation Method 2
forming a sealer configured to seal the hole by a melted material of the lid body by emission of laser light toward the hole from a second surface on a side opposite to the first surface of the lid body
Implementation Method 3
forming a sealer configured to seal the hole by a melted material of the lid body
Data Source
AI summary
An inertial sensor 1 includes: a base body; a lid body facing the base body; a functional element disposed in a cavity between the base body and the lid body and including a semiconductor layer; an adhesive layer disposed in a peripheral region surrounding the cavity and adhering the base body and the lid body to each other; and a sealer configured to seal a hole which communicates the cavity with an outside and which is disposed in the peripheral region. The sealer is provided in contact with the lid body and the base body, and includes a material of the lid body and a material of the adhesive layer.