Chip Package Laser Stop Structure for Sensor Fabrication
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Solution Overview
Problem
The existing processes for fabricating sensing devices like fingerprint and RF sensors are inefficient due to the time-consuming chemical vapor deposition and patterning processes, which affect the flatness of the sensing surface and increase costs.
Innovation Solution
A chip package design that includes a conductive pad, a laser stop structure, a first isolation layer, and a conductive layer, where a laser is used to form a smaller second through hole exposing the laser stop structure, reducing the need for extensive patterning and allowing for miniaturization, while maintaining electrical connectivity through a passivation layer and external conductive connection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional CVD and patterning processes are used to form isolation layers and openings, then electrical connectivity can be achieved, but process time and machine costs increase significantly
Solution Approach 1:
The patent extracts and eliminates the complex CVD and patterning processes from the fabrication flow. Instead of using conventional multi-step processes to form isolation layers and openings, the invention uses a laser stop structure that can be directly formed and exposed through simple through-hole etching, removing the time-consuming intermediate steps while maintaining the necessary electrical isolation and connectivity functions
Solution Approach 2:
The laser stop structure is formed in advance during the through-hole etching process itself. By designing the structure to be self-exposing through the etching process, the patent performs the isolation layer formation and opening creation in a preliminary action that combines multiple functions into one step, eliminating the need for subsequent CVD and patterning operations
2Reliability
If conventional patterning processes are used, then isolation layers can be formed, but the sensing surface flatness is compromised and detection accuracy is reduced
Solution Approach 1:
The patent removes the patterning process entirely from the fabrication sequence. By eliminating the depositing and etching cycles required for conventional isolation layer formation, the sensing surface remains undisturbed and maintains its inherent flatness, directly improving fingerprint detection accuracy without the need for additional surface processing steps
Solution Approach 2:
The patent replaces the mechanical/chemical patterning system with a laser-based approach. The laser stop structure is formed and exposed using laser energy rather than chemical etching and deposition, allowing precise control of the isolation structure formation without mechanical contact or chemical residue that would compromise surface flatness
3Productivity
If laser stop structure is used with through-hole etching, then process time is reduced, but additional structural components are required
Solution Approach 1:
The patent merges the formation of the through-hole and the exposure of the laser stop structure into a single etching operation. The isolation layer and the stop structure exposure are achieved simultaneously through one patterning and etching sequence, combining multiple fabrication functions into one integrated process step that improves productivity without requiring separate additional components
Solution Approach 2:
The laser stop structure serves multiple functions: it provides electrical isolation, acts as a reflective surface for laser-based processing, and enables precise positioning of subsequent layers. By making this single structure multi-functional, the patent reduces the need for additional separate components while maintaining high fabrication efficiency
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 reduces process time and machine costs, enhances the flatness of the sensing surface, and improves detection accuracy by eliminating the need for conventional patterning processes, thereby improving the efficiency and effectiveness of sensor fabrication.
Implementation Method 1
a laser is applied to remove a portion of the first isolation layer to form a second though hole, and the laser is stopped at the laser stop structure
Data Source
AI summary
A chip package included a chip, a first though hole, a laser stop structure, a first isolation layer, a second though hole and a conductive layer. The first though hole is extended from the second surface to the first surface of the chip to expose a conductive pad, and the laser stop structure is disposed on the conductive pad exposed by the first through hole, which an upper surface of the laser stop structure is above the second surface. The first isolation layer covers the second surface and the laser stop structure, and the first isolation layer has a third surface opposite to the second surface. The second though hole is extended from the third surface to the second surface to expose the laser stop structure, and a conductive layer is on the third surface and extended into the second though hole to contact the laser stop structure.