Deposition Rate Calculator

Professional notes on deposition rate

Deposition rate as a process control metric

Deposition rate links source power, pressure, and geometry to the film you build. In vacuum coating, stable rate minimizes thickness drift across wafers. Many labs flag a rate change above 5% to recondition targets, clean shields, or verify sensor calibration.

Typical rate ranges by technique

Thermal evaporation often runs from 0.1 to 5 nm/s, while magnetron sputtering commonly sits near 0.02 to 2 nm/s depending on power and gas flow. Chemical vapor deposition can be slower for conformal films but may reach tens of nm/min for throughput. The calculator converts these ranges into convenient units.

Thickness measurement pathways

Profilometry and ellipsometry provide post‑process thickness with strong traceability when sample preparation is consistent. Cross‑section imaging can validate dense films but adds uncertainty from cutting angle. If you already have thickness and time, the thickness‑time method gives the cleanest rate estimate.

Mass, area, and density approach

When weighing is reliable, mass gain offers a robust average over the coated area. The key is using exposed area, not substrate outline. Density must match microstructure; porous films can be 10–30% lower than bulk. The calculator computes areal mass, then thickness using x = m/(ρA).

QCM data and Sauerbrey assumptions

Quartz crystal microbalances translate frequency shift into areal mass for rigid, thin, evenly distributed films. The Sauerbrey constant is about 17.7 ng/(cm²·Hz) for 5 MHz crystals and scales with (5/f0)². Roughness or high damping can bias readings, so validate against thickness.

Uncertainty and repeatability

Small timing errors matter at high rates: a 1 s offset during a 60 s run is a 1.7% contribution. Thickness uncertainty can dominate for ultra‑thin coatings; a ±5 nm result on a 50 nm film is 10%. Enter uncertainties to obtain an estimated 1σ rate band.

Using forecasts for target thickness

Planning often starts from a target thickness and a safe window for drift. With an estimated rate, forecast thickness for an intended runtime or back‑calculate time for a target thickness. Combine forecasts with endpoint signals like shutter timing for tighter control. This reduces scrap and supports consistent optical and electrical properties each batch.

Reporting and data hygiene

Exported CSV and PDF outputs help standardize lab notebooks and quality records. Record method, density source, crystal frequency, harmonic, and any conditioning steps. If sensors disagree, log both values and investigate alignment, shadowing, and temperature effects before trusting one number.

FAQs

1. What is the deposition rate?

It is the film thickness grown per unit time, commonly reported as nm/min or Å/s. It can be derived from thickness measurements, mass gain with density, or QCM frequency shift data.

2. Which method should I choose?

Use thickness-time when you trust the thickness measurement. Use mass-area when weighing is accurate and density is known. Use QCM for in-situ monitoring, then verify occasionally with an independent thickness check.

3. Why does density matter?

Mass-based and QCM calculations convert areal mass to thickness using density. If the film is porous, amorphous, or contains voids, its effective density can be lower than bulk and will change the computed thickness and rate.

4. How accurate is the Sauerbrey approach?

It works best for rigid, thin, uniform films on the crystal. High roughness, viscoelastic layers, or heavy damping can break the assumption and distort mass estimates. Cross-check with thickness measurements when conditions are uncertain.

5. How do I use the uncertainty fields?

Enter your best 1σ estimates for thickness and time. The calculator propagates them for a quotient, providing an approximate 1σ rate uncertainty and relative percent uncertainty. Leave them blank to omit uncertainty outputs.

6. What does mass flux mean here?

Mass flux is deposited mass per area per time. It helps compare processes across substrates of different size. The tool reports mass flux in mg/cm²·min when enough data exist to compute areal mass.

7. Can I use this for multilayers?

Yes, if you calculate each layer separately with its own density and deposition time. For co-deposition or graded films, the effective density and thickness may vary, so interpret results as an average over the run.