Back-incident Image Sensor Light Shielding Film
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Solution Overview
Problem
Stray light entering the semiconductor substrate from the front surface of solid-state image pickup devices generates false signals, degrading image quality.
Innovation Solution
A light shielding film is provided over the front surface of the semiconductor substrate to cover the light receiving unit, preventing stray light from entering and improving image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If light receiving units are provided on the front surface of the semiconductor substrate, then the device can receive signal charges from photoelectric conversion, but stray light enters the semiconductor substrate from the front surface generating false signals
Solution Approach 1:
A light shielding film is introduced as an intermediary element between the front surface of the semiconductor substrate and the light receiving units. This film selectively blocks stray light from reaching the light receiving units while allowing the device to maintain its photoelectric conversion function on the back surface, thus resolving the contradiction between receiving valid signals and preventing stray light interference
2Reliability
If a light shielding film is provided over the front surface to cover the light receiving unit, then stray light is prevented from entering, but the device complexity increases
Solution Approach 1:
The invention employs a thin film light shielding layer deposited on the front surface of the semiconductor substrate. This thin film approach provides effective stray light blocking without significantly increasing device complexity, as the film can be integrated into the existing substrate structure and processed using standard thin film deposition techniques
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
The light shielding film effectively prevents stray light from entering the semiconductor substrate, resulting in enhanced image pickup quality by reducing false signals and ensuring accurate imaging.
Implementation Method 1
light incident on the back surface of a semiconductor substrate from an object is photoelectrically converted inside the semiconductor substrate
Implementation Method 2
a light shielding film provided over the front surface of the semiconductor substrate so as to cover the light receiving unit... to prevent light incident on the front surface from the outside
Data Source
AI summary
A solid-state image pickup device 1 includes a semiconductor substrate 10, light receiving unit 14 and light shielding film 20. The solid-state image pickup device 1 is back surface incident type and photoelectrically converts light indent on the back surface S2 of the semiconductor substrate 10 from an object into electrical charges and receives electrical charges produced by photoelectric conversion at the light receiving unit 14 to image the object. The light receiving unit 14 forms a PN junction diode with the semiconductor substrate 10. The light shielding film 20 is provided over a front surface S1 of the semiconductor substrate 10 so as to cover the light receiving unit 14. The light shielding film 20 serves to shield light incident on the front surface S1 from the outside of the solid-state image pickup device 1.