Pressure Unit Converter

What is Pressure?

Pressure is defined as force per unit area. In the SI system, the unit of pressure is the Pascal (Pa), where 1 Pa = 1 N/m² (one Newton per square meter). Pressure is a fundamental parameter in semiconductor manufacturing—from vacuum chambers (low pressure) to high-pressure CVD and deposition processes. Accurate pressure measurement and unit conversion are essential for process control, recipe development, and equipment specification.

Common Pressure Units

• Pa, kPa, MPa — SI units. 1 kPa = 1,000 Pa, 1 MPa = 1,000,000 Pa. Widely used in engineering and scientific applications.
• bar, mbar — 1 bar = 100 kPa ≈ 1 atm. Common in European industry and meteorology. 1 mbar = 0.001 bar = 100 Pa.
• atm (atmosphere) — Standard atmospheric pressure at sea level: 101,325 Pa. Used as a reference for vacuum and process pressure.
• psi (pounds per square inch) — US customary unit. 1 psi ≈ 6,895 Pa. Common in compressed air, hydraulics, and US equipment specs.
• mmHg, Torr — Based on the height of a mercury column. 760 mmHg = 1 atm. 1 Torr ≈ 1 mmHg ≈ 133.3 Pa. Frequently used in vacuum technology and semiconductor processes.

Conversion Method

All pressure units can be converted via Pascal (Pa) as the base unit. The conversion formula is:

P (Pa) = P (unit) × Conversion Factor (unit → Pa)

To convert from Pa to another unit, divide by the same factor:

P (target unit) = P (Pa) ÷ Conversion Factor (target unit → Pa)

Conversion factors (value in Pa per 1 unit):

Example Calculation

Convert 1 atm to kPa:

1 atm = 101,325 Pa = 101,325 ÷ 1,000 = 101.325 kPa

Convert 760 Torr to bar:

760 Torr = 760 × 133.3224 Pa = 101,325 Pa = 101,325 ÷ 100,000 = 1.01325 bar

Pressure in Semiconductor Manufacturing

In semiconductor fabrication, pressure ranges from high vacuum (10⁻⁶ Pa ~ mTorr) for sputtering and evaporation to near-atmospheric or high pressure for CVD and epitaxy. MFC specifications, chamber pressure readings, and process recipes often use different units (Torr, mbar, Pa, psi). Engineers must convert between these units accurately for cross-tool comparison, recipe migration, and process scaling.

FAQ

What is the relationship between mmHg and Torr?

1 Torr ≈ 1 mmHg. Both are based on the height of a mercury column at 0°C. Conventionally they are treated as equivalent for practical purposes.

Why is 1 atm = 101,325 Pa?

Standard atmospheric pressure is defined as the pressure exerted by a 760 mm column of mercury at 0°C at sea level. This corresponds to 101,325 Pa (or 101.325 kPa) in SI units.

Which unit is common for vacuum processes?

Torr and mbar are commonly used for vacuum chambers. High vacuum is often expressed in mTorr (10⁻³ Torr) or μbar (10⁻³ mbar).