Image Sensor ARC Coating and Via Etch Integration for Lower Cost
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Solution Overview
Problem
Current pad-open-last processes in image sensor manufacturing require separate deposition of anti-reflective coatings on microlenses and bond pad trenches, increasing manufacturing costs.
Innovation Solution
The method involves forming an anti-reflective coating on microlenses and along the inner border of bond pad trenches during the same processing step, using multiple photoresist and dry etching processes to create trenches and coat the bond pads efficiently.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If separate deposition processes are used for anti-reflective coating on microlenses and bond pad trenches, then coating quality is maintained, but manufacturing cost increases
Solution Approach 1:
The patent combines the deposition of anti-reflective coating on microlenses and bond pad trenches into a single processing step. The method forms a continuous anti-reflective coating layer that covers both the microlens array and the trench structures simultaneously, eliminating the need for separate deposition processes and reducing manufacturing cost
Solution Approach 2:
The anti-reflective coating process is designed to serve multiple functions simultaneously: it provides anti-reflective properties for microlenses, protects the bond pad trenches from impurities, and creates a uniform coating thickness across different structures. This multi-functional approach allows a single process to replace multiple specialized processes
2Productivity
If anti-reflective coating is deposited on microlenses and trench inner border in the same step, then manufacturing efficiency improves, but coating uniformity may be compromised
Solution Approach 1:
The patent applies local quality by forming the anti-reflective coating with spatially varying thickness characteristics. The coating is deposited to have a first thickness on the microlenses and a second thickness on the trench inner borders, with the second thickness being greater than the first. This localized thickness variation ensures proper coating quality in each region while maintaining a single deposition process
Solution Approach 2:
The method controls deposition parameters to achieve different coating thicknesses in different regions during the same deposition process. By adjusting deposition conditions and utilizing the geometric relationships between microlenses and trenches, the process achieves uniform coating quality across structures with different required thicknesses
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 manufacturing expenses by integrating the anti-reflective coating deposition into a single processing step, enhancing efficiency and cost-effectiveness in image sensor fabrication.
Implementation Method 1
performing a first developing process to form a first hole in the first photoresist layer above a bond pad of the image sensor
Implementation Method 2
performing a first dry etching process to form a first trench extending toward the bond pad from a top side of the image sensor
Implementation Method 3
forming an anti-reflective coating (ARC) layer on the planarization layer and along an inner border of the first trench
Data Source
AI summary
Image sensors and methods for fabricating image sensors. The method includes forming a first photoresist layer on a planarization layer. The method also includes performing a developing process to form a first hole above a bond pad. The method further includes performing a first dry etching process to form a first trench extending toward the bond pad. The method also includes forming an anti-reflective coating (ARC) layer on the planarization layer and along the first trench. The method further includes forming a second photoresist layer on the ARC layer and inside the first trench. The method also includes performing a developing process to form a second hole in extending from the ARC layer of the first trench to the top side of the image sensor. The method further includes performing a second dry etching process to form a second trench from the first trench to the bond pad.