IC Knowledge - Glossary

Glossary of Integrated Circuit Terminology - R

Radio Waves - Electromagnetic Waves with a Wavelength of approximately 3 kilometers to 30 centimeters.
RAM - Random Access Memory - memory devices where any memory cell in a large memory array may be accessed at in any order at random.
RAMBUS - a very high speed proprietary memory interface licensed to memory producers by RAMBUS (the company).
Rapid Thermal Annealer - an older terminology for rapid thermal processors.
Rapid Thermal Processor (RTP) - a type of semiconductor manufacturing equipment that can rapidly heat up and cool down semiconductor wafers. RTP is used to very rapidly heat a wafer up to a high temperature for annealing and diffusion processes. RTPs may ramp up at 25-10^oC/s ramp down at 30-50^oC/s.
Raw Process Time - the time it takes to perform a process with no waiting. Ignores waiting time, downtime, etc. RCA Clean - a type of semiconductor clean first developed at RCA. The RCA clean is the most widely used clean in the semiconductor industry today and utilizes a series of cleaning steps synergistically designed to remove particles, ionic and organic contaminants. See also, SC1, SC2.
RDRAM - RAMBUS DRAM.
Reactive Ion Etch (RIE) - a technique whereby radio frequency radiation is coupled into a low pressure gas to ionize the gas producing disassociation of the gas molecules into more reactive specie, and the substrate being etched is biased to induce ion bombardment. Compounds containing carbon (C) and halogens such as, fluorine (F), chlorine (Cl) or Bromine (Br) are typically used as gases. When the compounds disassociate in the plasma, both highly reactive halogen atoms or halogen compounds, and polymers that may deposit on the substrate blocking the highly reactive species are generated. Ions accelerated towards the substrate being etched by the applied or induced bias remove polymers on substrate surfaces oriented normal to the direction of ion motion, polymers coat substrate surfaces that are oriented parallel to the ion motion and block etching of those surfaces. Ion bombardment may also activate or accelerate chemical etching reactions. RIE therefore has the capability to etch surfaces normal to the direction of ion motion at a higher relative rate and surfaces parallel to the ion motion at a lower relative rate resulting in anisotropic etching. Typical RIE conditions are low pressure, low ionization levels and high ion energies relative to other dry etch techniques.
Recirculation air - air that flows into a cleanroom, out to a fan system and back into the cleanroom continuously. Recirculation air typically passes through an air filter immediately before entering the cleanroom so recirculation air provides continuous filtration of the room air.
Refractory Metals - metals with melting points >1,750^oC, although this definition varies. Some people use >1,900^oC and others use any metal with a melting point above Iron, Fe, Nickel, Ni and Cobalt, Co. Refractory metals include, Tungsten, W, Tantalum, Ta, Molybdenum, Mo, Niobium, Nb, and Zirconium, Zr. Regulators - devices that take a varying input and produce a controlled output. Electronic regulators may for example be, voltage regulators or current regulators, or gas systems may have pressure regulators.
Resistance (R) - a measure given in ohms of the resistance to the flow of electric current.
Resistivity - an intrinsic property of a material determining the materials resistance to the flow of current. Resistance in ohms is equal to the resistivity of the material multiplied by the cross sectional area of the material divided by the length of the material. Resistivity is frequently used to specify electrically active doping level and also as a measure of the ionic content of water.
Resolution - the size of the smallest feature a system can clearly define on a photoresist layer.
Reticle - a glass plate that contains a pattern of transparent and opaque areas. A reticle contains the pattern for one or more die but is not large enough to transfer a wafer sized pattern all at once.
Reverse Bias - a voltage placed across a junction in the reverse direction. When a junction is reverse biased, current flow is blocked until the junction breaks down.
RIE - see Reactive Ion Etch.
Rinse - the use of ultrapure water to remove chemicals from a wafer surface. Most wet cleaning and etching processes are immediately followed by a rinse.
Rinser - a piece of equipment used to perform rinsing.
ROM - Read Only Memory - a type of memory that is programmed during fabrication and the data can be read but never changed.
RPT - Raw Process Time - the time to complete a process assuming the process is completed without interruption.
RTA - see Rapid Thermal Annealer
RTP - See Rapid Thermal Processor