Transcript A Single-Chip CMOS Micro-Hotplate Array for Hazardous

A Single-Chip CMOS Micro-Hotplate
Array for Hazardous-Gas Detection and
Material Characterization
Presentation by
Hörður Mar Tómasson
16. October 2006
The principle of operation
• A sample of gas/material is exposed to a
temperature sweep.
• The heat absorbtion of the material at the
different temperatures is measured.
• The electrical resistance of a gas-sensitive
film is measured.
The hotplate
• A heater ring of polysilicon
• Layers of silicon oxide/nitride provide
thermal isolation from the chip bulk.
• Polysilicon temperature sensor in the centre
• Heated area diameter: 100 µm
• Electrical resistance of heater: 125 Ω.
• Power efficiency: 10.0°C/mW
Electrodes
• Structure of the electrodes that contact the
sensitive layer or the sample:
• CMOS aluminium metallization
• Ti/W layer that blocks diffusion
• Platinum film
Temperature control
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10 bit ADC for the temperature sensor
PID controller
10 bit DAC
DC amplifier drives the heater
The circuit
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Temperature control loops
Chip bulk temperature measurement
Resistance measurement of material
Chip communication
Logic for development of new controllers
using an FPGA