Stacked Light Detection Circuit Layout With Split Through-Vias
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Solution Overview
Problem
In stacked semiconductor structures, forming small-diameter through-vias in the second semiconductor substrate is challenging, leading to high area occupancy and reduced circuit space, necessitating a method to increase the circuit occupancy area within the substrate.
Innovation Solution
A light detection device with a stacked configuration of a first semiconductor substrate, a second semiconductor substrate, and a support substrate, where a smaller diameter through-via is formed in the second semiconductor substrate and a larger diameter through-via is formed in the support substrate, allowing for electrical connection via a re-distribution layer, thereby reducing the occupancy area of through-vias in the second semiconductor substrate and increasing circuit space.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a large-diameter through-via is formed in the second semiconductor substrate, then electrical connection between the second semiconductor substrate and support substrate is achieved, but the area occupancy rate of the through-via becomes high, reducing the circuit occupancy area
Solution Approach 1:
The through-via formation process is segmented into two independent stages: first forming a through-via in the second semiconductor substrate, then forming another through-via in the support substrate. This segmentation allows each through-via to be optimized independently, enabling the second semiconductor substrate to use a smaller diameter through-via while the support substrate uses a larger diameter through-via for mechanical stability.
Solution Approach 2:
Different regions of the stacked structure are assigned different through-via diameters according to their specific functional requirements. The second semiconductor substrate region uses small-diameter through-vias to maximize circuit occupancy, while the support substrate region uses large-diameter through-vias to ensure structural integrity and electrical connection reliability.
2Area of stationary object
If a small-diameter through-via is formed in the second semiconductor substrate, then the circuit occupancy area is increased, but it becomes difficult to form the through-via due to the substrate thickness
Solution Approach 1:
The manufacturing process is divided into separate steps for forming through-vias in different substrates. The second semiconductor substrate's through-via is formed first with smaller diameter requirements, followed by the support substrate's through-via formation which can accommodate larger diameters. This segmentation makes small-diameter through-via formation feasible despite substrate thickness constraints.
Solution Approach 2:
The through-via in the second semiconductor substrate is formed preliminarily before stacking with the support substrate. This preliminary action allows optimization of the through-via diameter for circuit occupancy purposes without being constrained by the need to penetrate the entire stacked structure, making small-diameter through-via formation achievable.
3Reliability
If a through-via penetrating both the second semiconductor substrate and support substrate is formed, then electrical connection is achieved, but the area occupancy rate increases due to the required large diameter
Solution Approach 1:
Instead of forming a single through-via penetrating both substrates, the electrical connection path is segmented into two separate through-vias: one in the second semiconductor substrate and another in the support substrate. This segmentation enables each through-via to be optimized for its specific function, reducing the overall area occupancy while maintaining connection reliability.
Solution Approach 2:
The electrical connection problem is solved by transitioning from a single vertical through-via to a multi-dimensional connection path involving multiple through-vias at different levels and positions. This dimensional approach allows the use of smaller through-vias in the second semiconductor substrate while maintaining overall connection integrity through the stacked structure.
Data Source
AI summary
The present disclosure relates to a light detection device and an electronic apparatus that are configured to be able to increase the circuit occupancy area within a substrate. Provided is a light detection device including: a first semiconductor substrate that includes a pixel portion in which a plurality of pixels each including a photoelectric conversion element are arranged; a second semiconductor substrate that includes a logic portion including a signal processing circuit required for processing a signal from the pixel portion; and a support substrate in which wiring is formed, the first semiconductor substrate, the second semiconductor substrate, and the support substrate being stacked, wherein electrical connection between wiring in the second semiconductor substrate and the support substrate is performed using a through via, a first through via is formed in the second semiconductor substrate, a second through-via is formed in the support substrate, and the first through via having a diameter smaller than that of the second through-via. The present disclosure can be applied to, for example, solid state imaging devices.