Image Sensor Stack Height Reduction via Integrated Vias
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Solution Overview
Problem
The existing manufacturing process for image sensor dies is complex and costly due to the numerous steps required, including the formation of through-oxide vias, light shielding structures, bond pads, color filter elements, and microlenses, which can be inefficient and increase the stack height.
Innovation Solution
The process is simplified by forming through-oxide vias and light shielding structures simultaneously, integrating color filter housing structures with TOVs, and using a common passivation layer for microlenses and bond pads, reducing the number of processing steps and stack height.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If through-oxide vias, light shielding structures, bond pads, color filter elements, and microlenses are formed using traditional separate processing steps, then each structure can be formed with proper electrical and optical properties, but the manufacturing process becomes complex and costly with increased stack height
Solution Approach 1:
The patent combines the formation of through-oxide vias and light shielding structures into a single integrated structure formed through one set of processing steps. The via structure includes both the conductive via portion and the light shielding portion as unified components, eliminating the need for separate formation processes for these two elements.
Solution Approach 2:
The integrated via structure serves multiple functions simultaneously: it provides electrical connection through the oxide layer, blocks light from reaching unwanted regions, and reduces overall stack height. This multi-functional design consolidates what would traditionally require separate specialized structures.
2Manufacturing precision
If multiple separate processing steps are used to form through-oxide vias, light shielding structures, bond pads, color filter elements, and microlenses, then each component can be optimized independently, but the manufacturing cost and time increase
Solution Approach 1:
The patent merges the processing steps for forming through-oxide vias and light shielding structures into a single integrated process. Color filter elements are also integrated into the via structures, and a common passivation layer is used for both microlenses and bond pads, significantly reducing the total number of processing steps required.
Solution Approach 2:
The integrated via structures are formed with embedded color filter elements during the initial via formation process, before subsequent processing steps. This preliminary integration of multiple functions into single structures early in the manufacturing process reduces the number of later processing steps required.
3Manufacturing precision
If traditional separate structures are used for through-oxide vias and light shielding, then each structure can be independently optimized, but the stack height increases
Solution Approach 1:
The patent merges the through-oxide via structure and light shielding structure into a single integrated via structure. The via structure includes both the conductive portion that penetrates the oxide layer and the light shielding portion, eliminating the need for separate stacked structures and thereby reducing the overall stack height.
Solution Approach 2:
The light shielding structure is nested within or integrated with the via structure, with the via structure containing both the electrical connection function and the light shielding function in a nested or combined configuration, reducing the vertical space required.
Data Source
AI summary
An imaging system may include an image sensor die stacked on top of a digital signal processor (DSP) die. The image sensor die may be a backside illuminated image sensor die. Through-oxide vias (TOVs) may be formed in the image sensor die and may extend at least partially into in the DSP die to facilitate communications between the image sensor die and the DSP die. Bond pad structures may be formed on the surface of the image sensor die and may be coupled to off-chip circuitry via bonding wires soldered to the bad pad structures. Color filter elements may be formed over active image sensor pixels on the image sensor die. Microlens structures may be formed over the color filter elements. An antireflective coating (ARC) liner may be simultaneously formed over the microlens structures and over the bond pad structures to passivate the bond pad structures.