Slow-Slow (SS) corner represents the slowest possible transistor performance — combining slow process, low voltage, and high temperature to create worst-case delay conditions, the critical corner for setup timing verification.

What Is SS Corner?

• Definition: Slow process + low voltage + high temperature.
• Characteristics: Maximum threshold voltage, minimum mobility, lowest drive current.
• Purpose: Verify setup timing, worst-case delays, minimum performance.

SS Corner Parameters

Process: Slow transistors (high Vth, low mobility). Voltage: Minimum supply (e.g., 0.9V for 1.0V nominal). Temperature: Maximum (e.g., 125°C or 150°C). Result: Slowest possible transistor switching.

Why SS Corner Matters?

• Setup Time: Critical paths must meet timing at slowest corner.
• Functionality: Chip must work even with slowest transistors.
• Yield: Determines which chips pass timing requirements.
• Guardbanding: Defines safety margins for manufacturing.

What Gets Verified

Setup Time: Ensure data arrives before clock edge. Critical Paths: Identify and fix slowest timing paths. Frequency: Determine maximum operating frequency. Functionality: Verify correct operation at slow corner. Margins: Ensure adequate timing slack.

Applications: Setup timing analysis, frequency binning, yield prediction, timing closure.

Typical Values: 30-50% slower than typical corner, 10-100× lower leakage than FF.

SS corner is the slowest marathon runner — if design meets timing here, it will work for all manufactured chips.