Stacked Image Sensor Memory Barrier Against Hydrogen Ingress
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Solution Overview
Problem
In stacked solid-state image pickup apparatuses, activated hydrogen generated from interlayer dielectric films during high temperature processes adversely affects storage elements like MTJ elements, leading to property deterioration, as conventional protective measures are insufficient in preventing hydrogen ingress from both side and end surfaces.
Innovation Solution
A dual protective film system is implemented, comprising a first protective film on the end surface and a second protective film on the side surface of storage elements, inhibiting hydrogen ingress from both junction and side surfaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a high temperature process (350°C to 400°C) is performed at a joining step to join stacked substrates, then the joining strength and reliability are improved, but activated hydrogen is generated from interlayer dielectric films causing storage element property deterioration
Solution Approach 1:
A protective film is introduced as an intermediary layer between the interlayer dielectric film and the storage element. This protective film acts as a barrier that prevents activated hydrogen generated during high temperature joining processes from reaching and damaging the storage element, thereby maintaining both joining reliability and storage element integrity
Solution Approach 2:
The protective film structure converts the harmful effect of high temperature processing by capturing and containing the activated hydrogen away from the storage element. The high temperature process continues to provide joining benefits while the protective film redirects the harmful byproduct (activated hydrogen) to a harmless location
2Device complexity
If only the side wall of storage element is protected by a protective film to prevent hydrogen ingress, then manufacturing complexity is reduced, but protection is insufficient as hydrogen can still enter from end surfaces
Solution Approach 1:
The protective film is segmented into multiple distinct regions: a side wall protective film covering the lateral surfaces and an end surface protective film covering the top/bottom surfaces. This segmentation allows each region to be optimized for its specific protective function, ensuring comprehensive hydrogen barrier coverage while maintaining manufacturing feasibility
Solution Approach 2:
The protective film structure extends from one-dimensional side wall coverage to two-dimensional coverage by adding end surface protection. This dimensional expansion ensures that hydrogen ingress paths from all directions (side and end surfaces) are blocked, providing complete protection without excessive complexity
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
The dual protective film system effectively prevents hydrogen from entering storage elements, thereby preserving their properties and functionality in the presence of activated hydrogen.
Implementation Method 1
a first protective film having a property of inhibiting entrance of hydrogen is formed on an end surface of a storage element included in the non-volatile memory which end surface is on a side facing the first structure, and a second protective film having the property of inhibiting entrance of hydrogen is formed on a side surface of the storage element
Data Source
AI summary
A solid-state image pickup apparatus includes a first structure having a first substrate, and a pixel region including a plurality of pixels which is formed in the first substrate, outputs pixel signals according to amounts of electric charges generated by photoelectric conversion, and is arrayed in a two-dimensional grid, and a second structure that is stacked on the first structure, and has a second substrate, and a logic circuit and a non-volatile memory that are formed in the second substrate, in which a first protective film having a property of inhibiting entrance of hydrogen is formed on an end surface of a storage element included in the non-volatile memory which end surface is on a side facing the first structure, and a second protective film having the property of inhibiting entrance of hydrogen is formed on a side surface of the storage element.