Info Gate

We thought that it would be nice to have a gateway to provide more information to our non technical visitors on some of the science and technology behind our products. We would welcome your input to enlarge and to enrich this database.

NANO-UV Glossary

DPP

(Discharge Produced Plasma) In DPP, electrical energy is used to ionize a gas (or mixture of gases), heating it to produce a high density plasma. Depending on the gas(es) used, their partial pressures, the amount and frequency of the power input, light in the EUV range (i.e., 13.5 nm) can be produced. This process is highly efficient since electrical energy is directly converted into plasma energy.

EUVL

(Extreme Ultra Violet lithography) Also known as EUV lithography is a next-generation lithography using the 13.5 nm wavelength. EUV is a significant departure from the deep ultraviolet (DUV) lithography used today. EUV lithography takes place in a vacuum as all matter absorbs EUV radiation. All the optical elements, including the photomask, must make use of defect-free Mo/Si multilayer which reflects light by means of interlayer interference; any one of these mirrors will absorb around 30% of the incident light. EUV source development has focused on plasmas generated by laser  (LPP) or discharge (DPP)  pulses. The mirror responsible for collecting the light is directly exposed to the plasma and is therefore vulnerable to damage from the high-energy ions and other debris.

HVM

(High Volume Manufacturing) This acronym is used often in the semiconductor manufacturing sector to identify a production system or process that performs to set industrial requirements. The requirements of the HVM become a benchmark that determines whether a process can be economical and of quality. For EUVL HVM, the desired throughput is 100 wafers per hour.

LPP

(Laser Produced Plasma) Relates to plasma produced by laser irradiation of a substance. Generally created by directing a laser at a target composed of a liquid, a solid, or a partially condensed gas. As the substance absorbs the high energy, energetic disassociation of the substance creates an ionized atmosphere (plasma). Depending on the power, frequency and the substance irradiated, the plasma can produce a wide range of energetic EUV photons. Two disadvantages of an LPP source is that the conversion of electrical energy into plasma is through an intermediate stage (the laser). LPP was the first EUV light source developed for the EUVL project in the United States at the end of the 90s. The conversion efficiency from laser power to EUV emission power is high but the system wide efficiency is poor, when the rather small efficiency of electrical to laser power is taken into consideration.

Microchips

Microchips are generally the basic components of modern miniaturized electronics. The chip is a series of electrical circuits built into a tiny wafer of silicon or another semiconductor. These circuits may be made by exposing the chip to a high temperature vapor of controlled composition. The vapor deposits a thin layer on the silicon to produce complex layers of materials such as those found in transistors.

Photolithography

In the photolithography process, elements to be created on the IC are reproduced in a pattern of transparent and opaque areas on the surface of a quartz plate called a photomask. The scanner passes light through the photomask, forming an image of the photomask pattern. The image is focused and reduced by a lens, and projected onto the surface of a silicon wafer that is coated with a photosensitive material called a photoresist. After exposure in the scanner, the coated wafer is developed like photographic film.

Plasma

A plasma is one of the four states of matter. It is similar to a gas, but consists of positively charged ions with most or all of their detached electrons moving freely. Plasmas are produced by very high temperatures, as in the sun and other stars, and also by the ionization resulting from exposure of a material to a dense electron current, such as an arc (spark). The energy level of plasma is determined chiefly by the gas density and the energy input level.

Resist

Resists are generally proprietary mixtures of a polymer or its precursor and other small molecules (e.g. photoacid generators) that have been specially formulated for a given lithography technology. The viscous polymer resists used during photolithography are called photoresists.

Scanner

(Stepper) The detailed patterns in semiconductor device fabrication are transferred using a type of stepper called a scanner, which moves the wafer and photomask with respect to each other during the exposure to increase the size of the area exposed. Elements of the circuit to be created on the IC are reproduced in a pattern of transparent and opaque areas on the surface of a plate called a photomask. The stepper passes light through the reticle, forming an image of the photomask pattern. The image is focused and reduced by a lens, and projected onto the surface of a silicon wafer that is coated with a photosensitive material called a photoresist.

Wafer

A wafer is a thin circular slice of a material such as pure silicon that has been doped to produce a semiconducting material on which an integrated circuit can be formed.