Window Die Recess Getter Structure for Wafer-Level FPA Vacuum Hold
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Solution Overview
Problem
Current wafer-level vacuum packaged uncooled focal plane arrays face limitations in getter sorption capacity due to restricted surface area for getter material deposition, which affects the maintenance of a sub-10 mTorr vacuum and optical transparency requirements.
Innovation Solution
An enhanced area getter architecture is implemented, utilizing a recess within the window die to increase the surface area for getter material deposition on die wall surfaces and the bonding side, thereby enhancing getter sorption capacity and serving as an optical blocking structure for optically blind reference pixels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a recess is added to the window die to increase getter surface area, then getter sorption capacity is improved, but device complexity increases
Solution Approach 1:
The patent introduces a recess structure that extends into the window die along a first direction, transforming a two-dimensional surface into a three-dimensional structure. This dimensional change increases the getter deposition surface area by utilizing the vertical depth of the recess, thereby enhancing getter sorption capacity without increasing the lateral footprint of the device.
Solution Approach 2:
The recess structure is integrated within the window die itself, nesting the getter deposition area inside the existing device architecture. This nesting approach allows the getter material to be disposed on the die wall surfaces formed by the recess, maximizing the use of available space within the window die structure.
2Quantity of substance
If the window die is made thinner to allow more getter material, then getter sorption capacity is improved, but structural strength deteriorates
Solution Approach 1:
Instead of reducing the overall thickness of the window die, the patent creates a recess that extends into the die along a first direction. This allows getter material to be deposited on the die wall surfaces within the recess, effectively increasing the getter area while preserving the external dimensions and structural integrity of the window die.
Solution Approach 2:
The window die is segmented into different functional regions: the recess area for getter deposition and the remaining structural portions. This segmentation allows the die to simultaneously provide structural support and accommodate the getter material without compromising overall strength.
3Quantity of substance
If getter material is disposed on die wall surfaces, then getter sorption capacity is improved, but manufacturing precision requirements increase
Solution Approach 1:
The recess structure provides defined die wall surfaces with controlled geometry, creating well-defined deposition zones for the getter material. This structured approach facilitates more uniform and controllable getter deposition compared to attempting to coat the entire window die surface, thereby managing manufacturing precision requirements.
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 increases the getter sorption capacity within the cavity, maintains a low-pressure environment, and effectively blocks light to improve the performance of infrared detector arrays while maintaining optical transparency.
Implementation Method 1
a getter material disposed on at least one of the die wall surface or the first die surface
Implementation Method 2
The die wall surface forms a perimeter of the recess
Implementation Method 3
the window die, the device die, and the seal ring form a hermetic cavity overlapping the infrared detector array
Data Source
AI summary
Methods and systems utilizing an enhanced area getter architecture for wafer-level vacuum packaged, uncooled focal plane array (FPA) assembly are disclosed. The FPA assembly includes a device die having a first device surface, an infrared detector array disposed on the first device surface, an infrared reference pixel disposed on the first device surface, and a window die bonded to the device die. The window die includes a recess and comprises a first die surface that overlies the infrared detector array, a second die surface that overlies the infrared reference pixel, and a die wall surface joining the first die surface and the second die surface. The die wall surface forms a perimeter of the recess and a getter material is disposed on at least one of the die wall surface or the first die surface.