Stacked Imaging Element Recess Structure for Stable Substrate Bonding
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Solution Overview
Problem
The existing technology faces difficulties in connecting the first and second semiconductor substrates due to variations in the height of the connection section, which affects the bonding process, leading to challenges in stacking and forming a stable imaging element.
Innovation Solution
An imaging element is proposed with a first semiconductor substrate for photoelectric conversion, a second semiconductor substrate for pixel circuit generation, an insulating layer, a connection section penetrating through the insulating layer to connect the substrates, and a recess on the insulating layer adjacent to the second substrate, facilitating consistent contact and bonding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the connection section is embedded in the insulating film to connect the first and second semiconductor substrates, then the substrates can be electrically connected, but the bonding becomes unreliable due to height variations of the connection section
Solution Approach 1:
The patent applies preliminary action by forming a recess in the insulating film before embedding the connection section. This recess pre-compensates for height variations, ensuring that the connection section's top surface aligns consistently with the insulating film surface. This preliminary structural preparation eliminates bonding inconsistencies caused by varying connection section heights, thereby improving both connection reliability and bonding consistency.
2Ease of manufacture
If the connection section height varies, then the manufacturing process becomes simpler, but the bonding with the second semiconductor substrate becomes difficult
Solution Approach 1:
The patent applies local quality by creating a recess specifically at the location where the connection section will be embedded. This localized structural modification allows the connection section to be formed with varying heights elsewhere in the structure while ensuring consistent height at the critical bonding interface. The recess is formed only where needed to accommodate the connection section, maintaining manufacturing simplicity while ensuring reliable bonding.
3Device complexity
If the connection section is formed without a recess, then the manufacturing process is simpler, but the contact with the second semiconductor substrate is inconsistent
Solution Approach 1:
The recess is formed in the insulating film as a preliminary step before bonding the second semiconductor substrate. This pre-formed recess ensures that when the connection section is embedded, its top surface will be at a consistent height relative to the insulating film surface. This preliminary structural preparation directly improves contact consistency without significantly increasing overall device complexity, as the recess can be formed using standard semiconductor fabrication processes.
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 ensures reliable connection and stacking of the semiconductor substrates, enhancing the stability and efficiency of the imaging element by maintaining consistent contact and reducing manufacturing defects.
Implementation Method 1
a photoelectric conversion section that performs photoelectric conversion of incident light
Data Source
AI summary
In an imaging element obtained by stacking a plurality of semiconductor substrates, connection between semiconductor substrates is facilitated. The imaging element includes a first semiconductor substrate, a second semiconductor substrate, an insulating layer, connection sections, and a recess. The first semiconductor substrate includes photoelectric conversion sections that perform photoelectric conversion of incident light. The second semiconductor substrate includes pixel circuits that generate an image signal corresponding to a charge generated by the photoelectric conversion, and the first semiconductor substrate is stacked on the back side of the second semiconductor substrate. The insulating layer is disposed between the first semiconductor substrate and the second semiconductor substrate. A connection section penetrates through the insulating layer and connects the first semiconductor substrate and the back side of the second semiconductor substrate. The recess is disposed on a surface of the insulating layer adjacent to the second semiconductor substrate and is formed around the connection sections.