Semiconductor Device Infrared Reflection Control
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Solution Overview
Problem
Conventional BGA type semiconductor devices with light receiving elements suffer from infrared rays passing through the light transparent substrate and reflecting off the wiring layer, causing patterns to be reflected on the output image, which affects image quality.
Innovation Solution
A semiconductor device with a reflection or anti-reflection layer formed between the light receiving element and the wiring layer, specifically along the side and back surfaces of the semiconductor substrate, to redirect or absorb infrared rays, preventing them from reaching the light receiving element and thus minimizing image distortion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a light transparent substrate is used to allow infrared rays to reach the light receiving element, then the light receiving element can detect infrared rays, but infrared rays pass through the substrate and reflect off the wiring layer, causing patterns to be reflected on the output image
Solution Approach 1:
A light absorbing layer is introduced as an intermediary between the light transparent substrate and the wiring layer. This layer absorbs infrared rays that pass through the substrate, preventing them from reaching the wiring layer and causing harmful reflections. The light absorbing layer acts as a mediator that blocks the harmful interaction between infrared rays and the wiring layer while allowing the light receiving element to function normally.
Solution Approach 2:
The wiring layer, which originally causes harmful reflections, is converted into a beneficial element by placing a light absorbing layer above it. The light absorbing layer absorbs the infrared rays that would otherwise reflect off the wiring layer, transforming the potential harmful reflection into a controlled absorption process. This converts the harmful effect of the wiring layer into a beneficial setup where the reflection is prevented.
2Volume of moving object
If the semiconductor substrate is made thin to reduce device size, then the device becomes more compact, but infrared rays can more easily pass through and reach the wiring layer, increasing reflection problems
Solution Approach 1:
The light absorbing layer serves as a mediator that addresses the reflection problem enabled by the thin substrate design. By introducing this intermediate layer, the patent allows the substrate to remain thin for compactness while the light absorbing layer prevents infrared rays from reaching the wiring layer and causing reflections.
3Length of stationary object
If the light receiving element is positioned close to the wiring layer to reduce device height, then the device profile is reduced, but infrared rays reflected from the wiring layer can more easily reach the light receiving element, worsening image quality
Solution Approach 1:
The light absorbing layer acts as a mediator positioned between the light receiving element and the wiring layer. It absorbs infrared rays before they can reflect off the wiring layer and reach the light receiving element, thereby protecting image quality even when the device height is reduced and the components are positioned closer together.
Solution Approach 2:
The close positioning of the light receiving element and wiring layer, which originally worsens reflection problems, is converted into an acceptable design by introducing the light absorbing layer. The layer absorbs the harmful reflected rays, transforming the potential image quality degradation into a controlled situation where the reflection is prevented despite the close spacing.
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 solution effectively prevents the reflection of wiring patterns on the output image, enhances the contrast and accuracy of the infrared ray detection by ensuring only intended light is received by the light receiving element, improving image quality and detection accuracy.
Implementation Method 1
a reflection layer formed between the light receiving element and the wiring layer and reflecting an infrared ray toward the light receiving element
Implementation Method 2
an anti-reflection layer formed between the light receiving element and the wiring layer and preventing transmission of an infrared ray
Data Source
AI summary
The invention provides a semiconductor device that solves a problem of reflection of a pattern of a wiring formed on a back surface of a semiconductor substrate on an output image. A reflection layer is formed between a light receiving element and a wiring layer, that reflects an infrared ray toward a light receiving element the without transmitting it to the wiring layer, the infrared ray entering from a light transparent substrate toward the wiring layer through a semiconductor substrate. The reflection layer is formed at least in a region under the light receiving element uniformly or only under the light receiving element. Alternatively, an anti-reflection layer having a function of absorbing the entering infrared ray to prevent transmission thereof may be formed instead of the reflection layer.