Bolometer Absorber Strengthening via ALD and Composite Layers
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Solution Overview
Problem
Traditional methods for fabricating bolometers face challenges such as temperature limitations, poor step coverage, thickness uniformity, and stress control, which affect the strength and rigidity of thin metal layers, leading to reduced sensor accuracy and dependability.
Innovation Solution
The use of atomic layer deposition (ALD) to form a thin metal absorber with a high temperature coefficient of resistance, combined with reinforcement trenches and anchor structures, to enhance the strength and rigidity of the absorber layer while maintaining low thickness, and the integration of a mirror and bond ring for efficient energy absorption and electrical connectivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If traditional deposition techniques (sputtering, evaporation, PECVD) are used to form thin metal absorber layers, then the fabrication process is simpler and faster, but the thin metal layers exhibit poor step coverage, thickness uniformity, and stress control, leading to reduced strength and rigidity
Solution Approach 1:
The patent applies composite materials by forming a multi-layer structure consisting of a thin metal absorber layer combined with a dielectric layer. The metal layer provides electromagnetic radiation absorption while the dielectric layer provides mechanical support and stress relief. This composite structure resolves the contradiction by maintaining the simplicity of traditional deposition for the metal layer while adding a supporting dielectric layer that enhances strength and rigidity without significantly increasing fabrication complexity.
Solution Approach 2:
The patent changes the deposition parameters by using atomic layer deposition (ALD) instead of traditional sputtering or evaporation techniques. ALD provides superior step coverage, thickness uniformity, and stress control compared to traditional methods. Although ALD is slower, the patent optimizes the process by controlling deposition temperature and using appropriate precursors to achieve the desired film properties while maintaining reasonable fabrication throughput.
2Reliability
If the metal absorber layer is made thinner to achieve better optical performance and lower cost, then the absorption efficiency improves, but the strength and rigidity of the absorber layer deteriorate
Solution Approach 1:
The patent uses composite materials by combining a thin metal absorber layer with a dielectric layer. The metal layer is kept thin (e.g., 10-100 nm) to optimize optical absorption and reduce cost, while the dielectric layer provides the necessary mechanical support and rigidity. This composite structure allows the thin metal layer to maintain its optical performance while the dielectric component ensures structural integrity.
Solution Approach 2:
The dielectric layer acts as an intermediary between the thin metal absorber layer and the substrate. It provides mechanical support to the fragile thin metal layer, stress relief to prevent cracking, and electrical isolation. This intermediary layer enables the use of thinner metal layers without compromising structural strength or reliability.
3Device complexity
If conventional fabrication processes are used, then the manufacturing process is simpler, but temperature control is limited and affects the quality and consistency of the deposited layers
Solution Approach 1:
The patent changes the deposition parameters by implementing precise temperature control during the atomic layer deposition process. The substrate temperature is maintained within a specific range (e.g., 100-300°C) to optimize precursor reactions, ensure uniform film thickness, and control internal stress. This temperature parameter control significantly improves manufacturing precision compared to conventional processes that lack such control.
Solution Approach 2:
The patent implements feedback control by monitoring deposition conditions in real-time and adjusting process parameters accordingly. Sensors monitor temperature, pressure, and film thickness during deposition, and the system automatically adjusts parameters to maintain optimal conditions. This feedback mechanism ensures consistent film quality and reduces variability between batches.
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 results in a bolometer with improved strength, rigidity, and accuracy, enabling efficient absorption of electromagnetic radiation and reliable temperature measurement, overcoming the limitations of traditional deposition techniques.
Implementation Method 1
Atomic layer deposition uncooled bolometer
Implementation Method 2
the efficiency of the absorber in a bolometer relates to the sensitivity and accuracy of the bolometer
Implementation Method 3
thermal detectors use the energy of said photons to increase the temperature of a component
Implementation Method 4
the temperature change caused by incoming photons can be measured using temperature-dependant resistors (thermistors)
Data Source
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AI summary
In one embodiment, a method of forming a semiconductor device includes providing a substrate, forming a sacrificial layer above the substrate layer, forming a first trench in the sacrificial layer, forming a first sidewall layer with a thickness of less than about 50 nm on a first sidewall of the first trench using atomic layer deposition (ALD), and removing the sacrificial layer.