Process materials (gases and chemicals)
Why are dopant gases such as diborane and phosphine often supplied diluted to low concentrations in hydrogen, nitrogen or similar?
- ATo change the gas's color
- BBecause only tiny amounts are needed, dilution makes the flow easier to control precisely and lowers toxicity and reactivity risks
- CTo strengthen the odor
Show answer and explanation
Answer: B. Because only tiny amounts are needed, dilution makes the flow easier to control precisely and lowers toxicity and reactivity risks
Dopants are added in very small amounts, so in pure form their flows would be too small to control precisely. Gases diluted to a few percent or ppm levels are easier to handle with flow meters and less dangerous if they leak.
- A. It is not to change the color.
- B. Correct. Dilution aids precise control and safety.
- C. It is not to strengthen the odor.