- SEMI MF110 - Test Method for Thickness of Epitaxial or Diffused Layers in Silicon by the Angle Lapping and Staining Technique
This Standard was technically approved by the Silicon Wafer Global Technical Committee. This edition was approved for publication by the global Audits and Reviews Subcommittee on February 1, 2018. Available at www.semiviews.org and www.semi.org in July 2018; originally published by ASTM International as ASTM F110; previously published September 2012.
Epitaxial growth and dopant diffusion processes are used extensively in the manufacture of silicon electron devices. Measurement of the resulting layer thickness is a key factor in the control of these processes. Epitaxial and diffusion layer thickness measurements are also used to determine the suitability of silicon wafers for subsequent steps in electron device manufacture.
This Test Method is suitable for process control, research and development, and materials acceptance purposes.
This Test Method covers a procedure suitable for interlaboratory comparisons of layer thickness. This Test Method is applicable for layers of any resistivity so long as the layer differs from the silicon substrate under it either in conductivity type or by at least one order of magnitude in resistivity. The method described is destructive in nature but is more widely applicable than the alternative infrared method, SEMI MF95.
For layers with thicknesses between 1 and 25 µm, an interlaboratory precision as defined in ASTM E177, of ±(0.15 T + 0.5 µm) (3S) can be achieved where T represents thickness expressed in micrometers.
Referenced SEMI Standards
SEMI C28 — Specification and Guide for Hydrofluoric Acid
SEMI C30 — Specification for Hydrogen Peroxide
SEMI C35 — Specification and Guide for Nitric Acid
SEMI M59 — Terminology for Silicon Technology
SEMI MF42 — Test Method for Conductivity Type of Extrinsic Semiconducting Materials
SEMI MF95 — Test Method for Thickness of Lightly Doped Silicon Epitaxial Layers on Heavily Doped Silicon Substrates Using a Dispersive Infrared Spectrophotometer