Semiconductor Device Backside Wiring Infrared Reflection
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Solution Overview
Problem
Conventional BGA type semiconductor devices with light receiving elements face issues due to infrared rays passing through light transparent substrates and reflecting off wiring layers, causing patterns to be reflected in output images, leading to image blurring and improper packaging.
Innovation Solution
Incorporating an infrared ray absorbent material into the protection layer and optionally providing an additional infrared ray absorption layer, and strategically positioning the wiring and conductive terminals to avoid overlapping with the light receiving element, along with the use of a reflection layer to enhance image clarity and packaging balance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a wiring layer is formed on the back surface of the semiconductor substrate, then electrical connection is achieved, but infrared ray reflection causes pattern reflection on output images
Solution Approach 1:
An infrared ray absorption layer is introduced as an intermediary between the wiring layer and the light receiving element. This layer selectively absorbs infrared rays while allowing visible light to pass through, thereby preventing infrared ray reflection that causes pattern reflection on output images without interfering with the electrical connection function of the wiring layer
Solution Approach 2:
The infrared ray absorption layer is positioned specifically in the region overlapping the light receiving element on the back surface of the semiconductor substrate. This localized placement ensures that only the critical area affected by infrared reflection is treated, maintaining electrical connectivity in other regions while eliminating harmful reflections where needed
2Illumination intensity
If a light transparent substrate is used, then light transmission is improved, but infrared rays pass through and reflect off the wiring layer
Solution Approach 1:
The infrared ray absorption layer serves as a mediator between the light transparent substrate and the wiring layer. It allows visible light to transmit through to the light receiving element while absorbing infrared rays before they can reach the wiring layer and cause harmful reflections
Solution Approach 2:
The infrared ray absorption layer changes the optical parameters of the substrate assembly by introducing selective wavelength absorption. It maintains high transmission for visible light wavelengths while introducing strong absorption for infrared wavelengths, effectively filtering the spectrum to prevent harmful reflections
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 solution effectively minimizes the impact of diffuse reflection, prevents pattern reflection on output images, and ensures proper packaging by absorbing or redirecting infrared rays, thereby enhancing image quality and reliability.
Implementation Method 1
an infrared ray absorbent material is mixed in the protection layer
Data Source
AI summary
This invention provides a semiconductor device that solves a problem that a pattern of a wiring formed on a back surface of a semiconductor substrate is reflected on an output image. A light receiving element (e.g. a CCD, an infrared ray sensor, a CMOS sensor, or an illumination sensor) is formed on a front surface of a semiconductor substrate, and a plurality of ball-shaped conductive terminals is disposed on a back surface of the semiconductor substrate. Each of the conductive terminals is electrically connected to a pad electrode on the front surface of the semiconductor substrate through a wiring layer. The wiring layer and the conductive terminal are formed on the back surface of the semiconductor substrate except in a region overlapping the light receiving element in a vertical direction, and are not disposed in a region overlapping the light receiving element.