Backside Contact Solid-State Image Sensor Alignment
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Solution Overview
Problem
The existing manufacturing processes for CMOS solid-state image pickup devices require complex steps and increased element area due to the need for separate processes to form alignment marks and contact portions, and the formation of pad electrodes on the light incidence side complicates the process, leading to higher costs and larger element areas.
Innovation Solution
A solid-state image pickup device and manufacturing method where the alignment mark and contact portion are formed using the same conductive material and insulating layers within holes extending through the silicon layer, allowing the pad electrode to be formed on the back surface side, reducing the need for a completely open opening through the silicon layer and simplifying the process by combining the formation of alignment marks and contact portions into a single step.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If separate processes are used to form alignment marks and contact portions, then the formation of lenses can be aligned with photodiodes, but the manufacturing process becomes complex and element area increases
Solution Approach 1:
The patent combines the alignment mark and contact portion into a single integrated structure formed by one conductive layer within one hole extending through the silicon layer. This merging eliminates the need for separate formation processes for alignment marks and contact portions, reducing manufacturing process complexity while maintaining alignment precision through the integrated design.
2Reliability
If pad electrodes are formed on the light incidence side, then electrical connection is achieved, but the opening must extend completely through the silicon layer increasing element area
Solution Approach 1:
The patent moves the pad electrode formation from the light incidence side to the back surface side of the silicon layer. By changing the spatial dimension where the pad electrode is formed, the opening no longer needs to extend completely through the silicon layer, thereby reducing element area while maintaining electrical connection reliability through the back surface connection path.
3Measurement precision
If alignment marks are formed by filling holes with insulating layers and conductive layers, then alignment is achieved, but the process differs from contact portion formation requiring additional steps
Solution Approach 1:
The patent designs the conductive layer and hole structure to serve dual functions: as the alignment mark for lens positioning and as the contact portion for electrical connection. This universal design allows the same formation process to achieve both alignment accuracy and electrical connection, eliminating the need for different formation steps for alignment marks and contact portions.
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 approach reduces the element area and simplifies the manufacturing process, lowering costs by eliminating the need for extensive opening formation and combining the alignment mark and contact portion formation into a single process.
Implementation Method 1
a pixel portion formed in the silicon layer for processing and outputting signal charges obtained by carrying out photoelectric conversion for incident lights
Data Source
AI summary
A solid-state image pickup device includes: a silicon layer; a pixel portion formed in the silicon layer for processing and outputting signal charges obtained by carrying out photoelectric conversion for incident lights; an alignment mark formed in a periphery of the pixel portion and in the silicon layer; and a contact portion through which a first electrode within a wiring layer formed on a first surface of the silicon layer, and a second electrode formed on a second surface opposite to the first surface of the silicon layer through an insulating film are connected, wherein the alignment mark and the contact portion are formed from conductive layers made of the same conductive material and formed within respective holes each extending completely through the silicon layer through respective insulating layers made of the same material.