Backside Illuminated EUV Sensor with Boron Protection
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Solution Overview
Problem
Existing radiation sensors for lithographic applications face challenges such as poor resolution, high noise, and sensitivity loss due to absorption by protective layers, particularly when using extreme ultraviolet (EUV) radiation, and are prone to damage from EUV and DUV radiation.
Innovation Solution
A backside-illuminated radiation sensor with a semiconductor layer comprising a p-n junction photodiode and a layer of p-doping protective material, such as boron, which is resistant to EUV and DUV radiation and deposited at a temperature below 500°C to avoid damaging internal circuitry, generating an internal electric field that complements the photodiode's field and minimizes dangling bonds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a protective layer is added to protect the sensor from radiation damage, then reliability is improved, but sensitivity is worsened due to absorption of radiation
Solution Approach 1:
A thin layer of silicon oxide (SiO2) is introduced as an intermediary protective layer between the semiconductor substrate and the harsh radiation environment. This SiO2 layer serves as a mediator that provides radiation damage protection while maintaining sufficient transparency to EUV and DUV radiation, thus resolving the contradiction between reliability and sensitivity
Solution Approach 2:
The thickness of the protective SiO2 layer is optimized to a specific range (e.g., 1-10 nm) to balance its protective function against radiation damage with its transparency to incident radiation. By controlling the thickness parameter, the layer provides adequate protection while minimizing absorption losses that would reduce sensitivity
2Reliability
If high temperature deposition is used to create protective layers, then protective material quality is improved, but device complexity increases due to damage to internal circuitry
Solution Approach 1:
The deposition temperature parameter is changed from conventional high temperatures to a reduced temperature range that is sufficient to form a quality protective SiO2 layer but low enough to prevent thermal damage to CMOS or CCD circuitry. This temperature optimization resolves the contradiction between protective layer quality and circuitry integrity
Solution Approach 2:
The sensor structure is segmented into distinct functional layers with the protective SiO2 layer positioned between the semiconductor substrate and the incident radiation. This segmentation allows each layer to be optimized independently - the SiO2 layer for protection and the semiconductor layer for detection - while avoiding the need for high-temperature processing that would damage integrated circuitry
3Adaptability or versatility
If conversion material is used to convert EUV/DUV photons to longer wavelengths, then detection capability is improved, but resolution and signal-to-noise ratio are worsened
Solution Approach 1:
The conversion material layer is completely removed from the sensor structure. Instead of converting EUV/DUV photons to longer wavelengths, the sensor directly detects incident EUV and DUV photons using the semiconductor substrate itself, eliminating the resolution degradation and signal-to-noise ratio losses that occur in conversion-based approaches
Solution Approach 2:
Conventional sensors use conversion materials to translate high-energy photons to visible light for detection. This invention inverts the approach by using the semiconductor substrate directly to detect high-energy EUV and DUV photons without conversion, leveraging the semiconductor's intrinsic photoelectric response at these wavelengths
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
The sensor provides improved stability and sensitivity for detecting EUV and DUV radiation, reducing radiation-induced damage and environmental degradation, while maintaining the integrity of CMOS or CCD circuitry.
Implementation Method 1
a semiconductor layer which comprises a photodiode comprising a region of n-doped semiconductor provided at a first surface of the semiconductor layer, and a region of p-doped semiconductor, wherein a depletion region is formed between the region of n-doped semiconductor and the region of p-doped semiconductor
Implementation Method 2
a layer of p-doping protective material provided on a second surface of the semiconductor layer... generating an internal electric field that complements the photodiode's field
Implementation Method 3
a depletion region is formed between the region of n-doped semiconductor and the region of p-doped semiconductor
Data Source
AI summary
A backside illuminated sensor comprising a supporting substrate, a semiconductor layer which comprises a photodiode comprising a region of n-doped semiconductor provided at a first surface of the semiconductor layer, and a region of p-doped semiconductor, wherein a depletion region is formed between the region of n-doped semiconductor and the region of p-doped semiconductor, and a layer of p-doping protective material provided on a second surface of the semiconductor layer, wherein the first surface of the semiconductor layer is fixed to a surface of the supporting substrate.