CMP Preston Removal Rate Calculator
Compute the chemical mechanical polishing removal rate from the linear Preston equation.
Description
Estimate chemical mechanical polishing removal rate with a linear Preston model using pressure, pad speed, and a calibrated coefficient.
The Preston model treats polishing removal rate as proportional to applied pressure and relative motion. This version uses pad speed in rpm, so its coefficient must be calibrated in the matching nm/(psi·rpm) units for the same equipment and process.
When to use CMP Preston Removal Rate Calculator
- Evaluate a calibrated first-order CMP process model
- Compare the proportional effect of pressure or pad rpm while holding other inputs fixed
- Back-check a removal-rate estimate against a recipe-specific Preston coefficient
How the calculation works
Removal rate is the product of pressure, pad rotational speed, and the supplied empirical coefficient. Doubling pressure or rpm doubles the model result when the coefficient remains fixed.1
removal rate = Preston coefficient × pressure × pad speed Interpreting the result
The coefficient absorbs the chosen units and process-specific behavior. It is not portable between tools that use linear surface velocity and this calculator's rpm input.
Assumptions and limitations
- RPM is rotational speed, not linear wafer-pad velocity; platen radius and relative wafer motion are not modeled.
- The linear model omits pad conditioning, slurry chemistry, pattern density, temperature, hydrodynamics, and pressure thresholds.
- Use a coefficient fitted to the same material, pad, slurry, machine, and unit convention.
References
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Material removal and surface figure during pad polishing of fused silica — Lawrence Livermore National Laboratory