CMOS handling precautions Why must complementary metal–oxide–semiconductor (CMOS) devices be handled with special care during storage, assembly, and lab work?

Introduction / Context:
CMOS inputs are insulated by a very thin gate oxide. This feature gives CMOS its high input impedance and low static power, but it also makes devices susceptible to electrostatic discharge (ESD). Understanding proper handling is essential in labs and manufacturing.

Given Data / Assumptions:

• Device technology: CMOS ICs with MOSFET gates.
• ESD sources include humans, tools, and packaging.
• Goal: prevent latent or catastrophic damage.

Concept / Approach:
Static charge can reach several kilovolts on a person walking across carpet. When discharged through a CMOS gate, the thin oxide can puncture or degrade, causing immediate failure or latent reliability issues. Proper ESD controls (wrist straps, mats, antistatic bags) reduce risk.

Step-by-Step Solution:

Verification / Alternative check:
Device data sheets specify ESD ratings (for example, HBM, CDM) and handling precautions. Field failures often trace back to improper ESD control.

Why Other Options Are Wrong:

• “Don’t get dirty”: Cleanliness matters, but ESD is the key risk.
• “Break easily”: Physical fragility isn’t the main issue—electrical overstress is.

Common Pitfalls:
Leaving CMOS inputs floating can also cause oscillations and increased power; always tie unused inputs to defined levels using proper biasing.

Final Answer:
Because they can be damaged by static electricity discharge.