NIST physical science technician Douglas Alderson adjusts a pressure valve on a plasma reference cell. The ultrahigh vacuum cell is used to study ways to improve the manufacture of semiconductor integrated circuits. Plasmas, partially ionized gases, are used in semiconductor processing to selectively etch circuit patterns into silicon wafers and other materials. In a joint effort, NIST physics, chemistry, and electronics researchers are devising ways to accurately monitor important plasma variables, such as the concentration and spatial uniformity of ions and radicals within the vacuum chamber. The NIST researchers are collaborating with 22 other industrial, academic, and government laboratories in the U.S. and abroad -- which have identical reference cells -- to better characterize the properties of plasma processing reactors.