CMOS Compatible Hydrogen Sensor Using Platinum Gate and ALD-Aluminum Oxide

Area of Science:

• Materials Science
• Semiconductor Device Physics
• Chemical Sensing

Background:

• Hydrogen sensors are crucial for safety and industrial process monitoring.
• Existing sensors often face challenges with fabrication compatibility and reliability.
• Atomic Layer Deposition (ALD) offers precise thin-film fabrication for semiconductor devices.

Purpose of the Study:

• To fabricate and characterize a novel p-Si/ALD-Al2O3/Ti/Pt Metal Oxide Semiconductor (MOS) device for hydrogen sensing.
• To evaluate the sensor's performance using a reliable, industry-compatible CMOS fabrication process.
• To assess the integration potential of ALD-Al2O3 in CMOS post-processing.

Main Methods:

• Fabrication of a p-Si/ALD-Al2O3/Ti/Pt MOS stack.
• Utilizing Atomic Layer Deposition (ALD) for the Al2O3 layer.
• Testing the device's response and recovery characteristics with varying hydrogen concentrations at elevated temperatures.

Main Results:

• The fabricated MOS device demonstrated a clear correlation between capacitance variation and hydrogen concentration.
• Successful hydrogen detection down to 20 ppm at 140 °C was achieved.
• A response time of 56 seconds was recorded for a 500 ppm hydrogen concentration.

Conclusions:

• The p-Si/ALD-Al2O3/Ti/Pt MOS device is a viable candidate for hydrogen sensing applications.
• The CMOS-compatible fabrication process ensures industry relevance and scalability.
• ALD-Al2O3 is suitable for integration into back-end-of-line (BEOL) or post-processing CMOS steps.