Micron

Notes

Packaging and advanced packaging conversations stayed in microns even as front-end moved to nanometres.

Overview

A micron is one millionth of a metre, the everyday name for the micrometre (symbol µm). Chipmakers used it to name process generations before nanometre names took over, as in a 0.35 micron process, and it remains a natural unit for larger dimensions, such as film thicknesses in lithography. The name is no longer part of the SI: the official name is micrometre, though micron is still common across the industry.

How it works

The micrometre is the metre combined with the SI prefix micro, which stands for a factor of ten to the minus six and uses the symbol µ. The name micron, with µ alone as its symbol, was once an accepted unit, but the General Conference on Weights and Measures abrogated it in 1967, since µ had by then become a prefix. Formal documents therefore write micrometre or µm, while engineers often still say micron. One micron equals 1,000 nanometres.

In process naming, the number once matched real dimensions. Semiconductor Engineering notes that in the early 1990s a 0.5 µm or 0.35 µm process meant that the key dimensions lined up with the name. Intel's 1998 technology journal discusses its 0.5, 0.35 and 0.25 micron generations, and TSMC's CyberShuttle prototyping service still covers a range running from 0.5 µm to its A14 technology. Later generations were named in nanometres, and those names drifted away from physical sizes.

Many dimensions in a fab are still most naturally expressed in microns. In one of Chris Mack's lithography tutorials, for example, the resist film is about 0.9 µm thick, the printed features are 0.35 µm lines and spaces, and focus positions are plotted in microns.

Examples

• A prototype run on a 0.5 µm process, the oldest technology in the range TSMC lists for its CyberShuttle service.
• Intel's 0.25 micron process generation, transferred to its factories using the Copy EXACTLY! method.
• An i-line lithography process with photoresist about 0.9 µm thick printing 0.35 µm lines, as in a published tutorial example.
• Older design kits and process documents for mature nodes that state their generation in microns rather than nanometres.

Why it matters

Anyone reading older process documentation, mature-node design kits, lithography data or packaging drawings meets microns daily, and confusing micrometres with millimetres or nanometres is an easy way to make an expensive mistake. Process engineers, lithography engineers, package engineers and wafer suppliers use the unit routinely.

In the chip lifecycle, micron-scale dimensions appear in materials and wafer specifications, in mature process nodes still running in production, in thinning, bumping and packaging after the fab, and in failure analysis, where defects and cross-sections are often measured in microns.

It matters most to: Lithography Process Engineer, Process Integration Engineer, Silicon Wafer Manufacturing Engineer, Wafer Bumping Process Engineer

Common confusions

Not the same as Micron Technology

Micron Technology is a memory and storage company that began in 1978 in Boise, Idaho. Context usually makes clear whether the company or the unit is meant.

Not the same as nanometre

A nanometre is a thousand times smaller than a micron. Process names moved from microns to nanometres, so 0.18 micron and 180 nm describe the same size. Micron vs nanometre

Not the same as mil

A mil is a thousandth of an inch, which is 25.4 µm, not a millionth of a metre; the two are easy to mix up on drawings that use imperial units.

Sources

1. Resolution 7 of the 13th CGPM (1967): Abrogation of earlier decisions (micron, new candle) (opens in a new tab), BIPM, 2026-10-22
2. A Node By Any Other Name (Barry Pangrle, 12 May 2014) (opens in a new tab), Semiconductor Engineering, 2026-10-22
3. The Evolution of Intel's Copy EXACTLY! Technology Transfer Method (Chris J. McDonald, Intel Technology Journal, Q4 1998) (opens in a new tab), Intel, 2026-10-22
4. CyberShuttle (opens in a new tab), TSMC, 2026-10-22
5. Swing Curves and the Process Window (Chris A. Mack, The Lithography Expert, Winter 1998) (opens in a new tab), Chris A. Mack, Lithoguru, 2026-10-22
6. About Micron (opens in a new tab), Micron Technology, 2026-10-22

Related terms

• Nanometre
• Angstrom
• Process node
• 200mm

Where it appears on the Hub

Used on 29 pages of the Hub. In each group, the pages that mention it most come first.