Rear Surface Incident Light Receiving Device Electrode Segmentation

Solution Overview

Problem

Rear surface incident type light receiving devices face challenges in achieving increased operation speed and cost reduction, as reducing electrode area for speed enhancement complicates wafer-state inspection, while increasing electrode area for inspection purposes hinders speed improvements due to increased parasitic capacitance.

Innovation Solution

A method involving a two-step process: first, performing characteristic inspection by applying a probe to a part of the electrode after its partial formation, and second, reducing the electrode area in plan view to achieve both high-speed operation and wafer-state inspection capabilities, with specific electrode configurations such as a mirror electrode with a larger outermost diameter for inspection and a smaller diameter for reduced parasitic capacitance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If the area of the electrode is reduced to achieve an increase in operation speed, then the parasitic capacitance is reduced and operation speed increases, but it becomes difficult to apply a probe for inspection to the electrode, so that the characteristic inspection in the wafer state cannot be performed

Engineering Contradiction:

Improveoperation speedVSAvoidease of probe application

Core Design Contradiction:

SpeedVSEase of operation

Solution Approach 1:

The electrode is divided into two distinct parts: a first electrode part with a larger area that serves as the inspection electrode for probe application, and a second electrode part with a smaller area that serves as the operational electrode for signal transmission. This segmentation allows the inspection function and operational function to be performed by different portions of the same electrode structure, resolving the contradiction between needing a large area for inspection and a small area for high-speed operation.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The first electrode part is designed to serve multiple functions: it acts as both the inspection electrode for wafer-state characteristic inspection and as part of the overall electrode structure for electrical connection. This multi-functionality allows the same structural element to fulfill both inspection requirements and operational requirements, eliminating the need for separate inspection structures.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Ease of operation

If the area of the electrode is increased for the characteristic inspection to be performed in the wafer state, then the probe can be applied for inspection, but an increase in operation speed cannot be achieved due to an increase in parasitic capacitance

Engineering Contradiction:

Improveease of probe applicationVSAvoidoperation speed

Core Design Contradiction:

Ease of operationVSSpeed

Solution Approach 1:

The electrode is divided into two distinct parts: a first electrode part with a larger area that serves as the inspection electrode for probe application, and a second electrode part with a smaller area that serves as the operational electrode for signal transmission. This segmentation allows the inspection function and operational function to be performed by different portions of the same electrode structure, resolving the contradiction between needing a large area for inspection and a small area for high-speed operation.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different parts of the electrode have different area characteristics optimized for their specific functions: the first electrode part has a larger area locally optimized for probe inspection, while the second electrode part has a smaller area locally optimized for minimizing parasitic capacitance. This local differentiation of properties allows each region to excel at its intended function without compromising the other.

Inventive Principle:

Principle #3Local quality

Data Source

PatentUS11339494B2Rear surface incident type light receiving device comprising an uppermost part of an electrode with a larger diameter than lowermost part of the electrode

Publication Date: 2022.05.24 MITSUBISHI ELECTRIC CORP

AI summary

According to the present invention, a method for manufacturing a rear surface incident type light receiving device including a substrate, a light receiving unit formed on a surface of the substrate and an electrode formed on the light receiving unit and electrically connected to the light receiving unit includes a first step of performing, after formation of a part of the electrode, a characteristic inspection of the rear surface incident type light receiving device by applying a probe to a part of the electrode and a second step of reducing an area of the electrode in a plan view.