TID, DD and SEE

Question 1

What does ELDRS mean and what devices does it affect?

Answer 1

ELDRS is enhanced-low-dose-rate-sensitivity

Bipolar devices are susceptible to ELDRS and it means that their lifetime is often shorter than expected despite what testing with high radiation exposure on the ground suggests

Question 2

How does TID tolerance vary between Bipolar, CMOS and hybrid BiCMOS technologies

Answer 2

bipolar and cmos more resistant to TID effects than hybrid BiCMOS

Question 3

What two features does hybrid BiCMOS try to make use of?

Answer 3

• High speed and current drive of the bipolar technologies
• low power and high-packing density of CMOS

Question 4

What is the stackup for the hybrid BiCMOS technology like?

Answer 4

1. Nitride layer
2. deposited oxide
3. aluminium-based tracks
4. glass
5. field oxide

Question 5

What is the mechanism for TID damage?

Answer 5

Charges trapped inside of insulating materials such as the oxide in the transistors or other parts of the spacecraft

Question 6

What four changes are caused by TID?

Answer 6

1. Altered populations of charge trapping sites
2. charge build up
3. changes in chemical bonding
4. decomposition

Question 7

What happens to p and n channel MOS devices threshold voltage when holes are trapped in the gate oxide?

Answer 7

The threshold voltage is decreased

Question 8

What is the thickness of the shielding used to stop trapped electrons? What particles cannot be stopped with this shield?

Answer 8

• 3 g cm^-3 or about 100 mm aluminum thickness
• it cannot stop trapped protons or high energy protons or heavy ions from GCRs

Question 9

What is meant by overrating?

Answer 9

operating a device well below its threshold voltage to minimise chances of SEB