Optical Fingerprint Sensor Scribe Line Etching for Delamination Prevention
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Solution Overview
Problem
Existing optical fingerprint sensors face challenges in production yield and reliability due to defects caused by wafer dicing, leading to delamination at the corners or edges of semiconductor devices during reliability tests.
Innovation Solution
A method involving a cutting process and an etching process to remove materials above the scribe line before wafer dicing, forming a light shielding layer with transparent pillars and a light collimating layer to reduce defects and improve reliability, where the etching process exposes the scribe line without damaging the substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If wafer dicing is performed directly without removing material above the scribe line, then the cutting process is simple and fast, but micro-cracks and peeling occur during cutting leading to low reliability
Solution Approach 1:
The patent applies preliminary action by performing a cutting process and etching process before wafer dicing to remove material above the scribe line. This preliminary removal of material prevents micro-cracks and peeling during the subsequent dicing operation, thereby improving reliability without significantly complicating the overall manufacturing process
Solution Approach 2:
The patent segments the material removal process into distinct stages: first a cutting process to create an opening, then an etching process to remove remaining material above the scribe line. This segmentation allows for controlled removal of material while preserving the integrity of the substrate and underlying structures
2Manufacturing precision
If the etching process removes all material above the scribe line, then the scribe line is fully exposed for clean cutting, but the substrate may be damaged
Solution Approach 1:
The patent applies local quality by selectively removing material only in the region above the scribe line while preserving the substrate and underlying structures. The etching process is localized to remove material laterally from the opening until the scribe line is exposed, without compromising the overall substrate strength or integrity of functional areas
Solution Approach 2:
The patent uses an intermediary approach by first creating an opening through a cutting process, then using an etching process as an intermediate step to remove remaining material. This intermediary etching step allows for controlled material removal that exposes the scribe line while maintaining substrate integrity, serving as a bridge between the initial cutting and final dicing operations
3Productivity
If traditional optical sensors are used, then the structure is simple, but production yield and reliability need further improvement
Solution Approach 1:
The patent applies preliminary action by removing material above the scribe line before wafer dicing through a combination of cutting and etching processes. This preliminary material removal prevents defects such as micro-cracks and peeling that would otherwise occur during dicing, thereby improving production yield without significantly increasing structural complexity
Solution Approach 2:
The patent applies the extraction principle by removing the problematic material above the scribe line before the dicing process. This extraction of excess material eliminates the source of defects that would compromise yield and reliability, allowing for cleaner cuts and fewer defective devices
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 effectively reduces the risk of micro-cracks and peeling during cutting, enhancing the reliability of semiconductor devices by eliminating delamination issues and improving the sensitivity and collimation of light, thereby increasing production yield.
Implementation Method 1
performing an etching process along the opening to remove the remaining material until the scribe line is exposed
Implementation Method 2
The function of the light collimator is to collimate light to reduce power loss caused by light divergence
Implementation Method 3
forming a light shielding layer over the substrate and over the transparent pillars
Data Source
AI summary
A method for forming a semiconductor device is provided. The method includes providing a substrate having a scribe line, forming a sensing pixel array in the substrate, forming a plurality of transparent pillars over the substrate, and forming a light shielding layer over the substrate and the transparent pillars. The sensing pixel array has a plurality of sensing pixels, and each of the transparent pillars is correspondingly disposed on one of the sensing pixels of the sensing pixel array. The method further includes performing a first cutting process to form an opening directly above the scribe line, while leaving the remaining material covering the scribe line, and performing an etching process along the opening to remove the remaining material until the scribe line is exposed.