Backside Illuminated Light-Receiving Device Asymmetric Mesa Positioning
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Solution Overview
Problem
Backside illuminated semiconductor light-receiving devices face challenges in enhancing frequency characteristics without compromising assembling operability, as existing designs either lead to mesa portion breakage or elongated connection lines that deteriorate frequency performance.
Innovation Solution
A rectangular semiconductor substrate with a mesa-shaped light receiving portion and sub mesa portions, where the distance from the light receiving portion to one side is set shorter than half the length of adjacent sides, and electrodes are formed on wider surfaces to distribute pressure and reduce connection line lengths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the light receiving mesa portion is positioned at the center of the semiconductor substrate, then pressure distribution is improved, but connection line length increases and frequency characteristics deteriorate
Solution Approach 1:
The light receiving mesa portion is deliberately positioned asymmetrically on the semiconductor substrate, specifically at a location where the distance to one side is shorter than half the length of adjacent sides. This asymmetric positioning resolves the contradiction by optimizing the balance between pressure distribution during mounting and connection line length for frequency performance, rather than using symmetric center positioning.
2Stress or pressure
If the upper surface area of the light receiving mesa portion is increased, then pressure concentration is reduced, but the mesa portion becomes more prone to breaking during mounting
Solution Approach 1:
The patent creates local quality differences by forming sub mesa portions with larger upper surface areas around the light receiving mesa portion. These sub mesa portions specifically address the pressure concentration issue at critical locations during mounting, while the light receiving mesa portion itself maintains its optimized smaller area for mechanical strength and frequency performance.
3Stress or pressure
If three mesa portions are formed in a row on the center portion of the substrate, then pressure distribution is improved, but handling difficulty increases due to warping
Solution Approach 1:
Instead of forming three mesa portions symmetrically in a row at the center, the patent uses asymmetric positioning with one light receiving mesa portion and multiple sub mesa portions located at specific positions. This asymmetric configuration prevents warping during vacuum collet mounting while still providing adequate pressure distribution, thereby improving handling ease without sacrificing mechanical stability.
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 configuration enhances frequency characteristics by reducing pressure on the light receiving mesa portion and shortening connection lines, thereby improving assembling operability and maintaining high-frequency performance in optical receiver modules.
Implementation Method 1
a backside illuminated semiconductor light-receiving device is a photoelectric conversion element which includes a semiconductor substrate and a light receiving part which is formed on a front surface of the semiconductor substrate, and receives light incident from a back surface of the semiconductor substrate by the light receiving part
Data Source
AI summary
Provided is a backside illuminated semiconductor light-receiving device enhancing a frequency characteristic without deteriorating assembling operability. The light-receiving device includes a rectangular substrate; a light receiving mesa portion formed on a center portion of one side on a front surface of the substrate and includes a PN junction portion; a P-type electrode formed on the light receiving mesa portion and conductive with one side of the PN junction portion; an N-type electrode mesa portion formed on one corner portion of the one side; an N-type electrode pulled out to the N-type electrode mesa portion and conductive with the other side of the PN junction portion; a P-type electrode mesa portion and a dummy electrode mesa portion formed in a region including three other corner portions; and a dummy electrode formed on the dummy electrode mesa portion.