Multipixel Detector Pixel Isolation Without Absorber Etch Damage
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Solution Overview
Problem
Existing methods for producing multipixel detectors, particularly thin film photodiodes, face challenges such as lithographically related damage and etch-related damage, leading to defective pixels and increased costs, especially when using thick film single crystalline pn-junctions or materials like InAs, which are expensive and inefficient in the short-wave infrared wavelength region.
Innovation Solution
A method involving the deposition of photon absorbing materials in openings within an electrically insulating layer, followed by planarization to form a common top electrode, which reduces damage and enables cost-efficient production of high-quality multipixel detectors with fewer defective pixels by avoiding direct lithographic patterning and etching of the photon absorbing material.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If lithographic patterning and etching are used to form separate pixels, then pixel separation is achieved, but the photon absorbing material suffers damage and degradation
Solution Approach 1:
The patent divides the pixel separation function into two parts: the electrically insulating layer is patterned using lithography to create separated regions, while the photon absorbing material is deposited as a continuous layer that naturally conforms to the underlying structure, avoiding direct lithographic damage to the sensitive material
Solution Approach 2:
The electrically insulating layer serves as an intermediary between the lithographic patterning process and the photon absorbing material. The lithography targets the insulating layer rather than the photon absorbing material directly, protecting the latter from harmful UV exposure and etch damage while still achieving pixel separation through the insulating layer's patterned structure
2Reliability
If thick film single crystalline pn-junctions or InAs materials are used, then detector performance is improved, but production cost increases significantly
Solution Approach 1:
The patent changes the material parameter from expensive thick film single crystalline pn-junctions or InAs to cost-effective thin film photodiode structures using solution-based PbS quantum dots, achieving comparable or superior performance in the SWIR region while dramatically reducing material and production costs
Solution Approach 2:
The patent employs inexpensive thin film materials and solution-based deposition techniques that enable high-volume, low-cost production of SWIR detectors, replacing expensive proprietary materials with commercially available, easily processed alternatives that maintain detector functionality
3Ease of manufacture
If a common top electrode is formed over the flat surface, then manufacturing simplicity is improved, but electrical insulation between pixels must be maintained
Solution Approach 1:
The planarized electrically insulating layer acts as an intermediary barrier between the common top electrode and the underlying pixel structures. This insulating layer maintains electrical isolation between pixels even though they share a common top electrode, while the planarization process creates a uniform surface that simplifies subsequent manufacturing steps
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 facilitates the production of high-quality multipixel detectors with reduced damage to photon absorbing materials, enabling efficient use in the short-wave infrared region and compatibility with CMOS production methods, resulting in a cost-effective and reliable imaging device with fewer defective pixels.
Implementation Method 1
one of the thin film layers comprise photon absorbing material... detect light... absorb a photon
Implementation Method 2
planarizing the deposited electrically insulating layer, the deposited first photon absorbing material and the deposited second photon absorbing material to form a flat surface
Implementation Method 3
A TFPD comprises one or more thin film layers... depositing an electrically insulating layer... depositing a first photon absorbing material
Data Source
Figure 1~2
Figure 3
Figure 4~4(l)
AI summary
A method (100) for producing a multipixel detector (10), the method (100) comprising: providing (S102) a bottom layer (20) comprising a first (21) and a second (22) bottom electrode; depositing (S104) an electrically insulating layer (30) on the bottom layer (20); forming (S106) a first opening (31) through the electrically insulating layer (30); depositing (S108) a first photon absorbing material (41) in the first opening (31); forming (S114) a second opening (32) through the electrically insulating layer (30); depositing (S116) a second photon absorbing material (42) in the second opening (32); planarizing (S118) the deposited electrically insulating layer (30), the deposited first photon absorbing material (41) and the deposited second photon absorbing material (42) to form a flat surface (50); forming (S122) a common top electrode (60) on top of the flat surface (50).