Attribute / Description

Sensitivity	Electron dose in (C/cm2) coulombs per square centimeter required for the degree of electron-induced reaction to occur so a specific solvent developer will give an acceptable image. The sensitivity of PMMA scales roughly with electron accelerating voltage, with a critical dose at 50kV, for example, being about twice that of 25kV exposure.
Contrast	Related to the slope on an image
Adhesion	Ability of material to adhere to substrate without substantial undercut during develop or wet etch.
Etch Resistance	Ability to withstand acid and basic chemical etching solutions.
Resolution	Smallest useable image capable of being produced by the resist/developer/process.
Edge Acuity	Quality of the edge of an image, determined by adhesion, shot noise
Process Window	Tolerance to a change e.g. +-10% in exposure dose vs. a CD change.
Shelf Life	Time before which a resist will continue to retain specific performance parameters. Usually, lower storage temperature will extend shelf life.

		Acronyms / Glossary of Terms

ATM	asynchronous-transfer-mode
CCD	charge-coupled-device
CDMA	code-division multiple-access
CMOS	complementary-metal-oxide-semiconductor
CVD	chemical vapor deposition
DCF	dispersion-compensating fibers
Dark Fiber	Inactivated fiber-optic line and no associated opto-electronics. Dark fiber refers to the physical cable itself, rather than a certain amount of bandwidth or transport capacity. Massive amounts of dark fiber are being deployed by telephone companies and utilities, in anticipation of eventual use when the opto-electronics can be added at lower costs.
DWDM	dense-wavelength-division multiplexing; Dense Wavelength Division Multiplexers have become one of the hottest commodity items in light-wave applications today. The multiple-channel WDM exploded on the scene in 1996 in commercial form and should be well entrenched in fiber-optic systems by the end of 1997. Sixteen-channel components and systems are headed for wide use in the form of so-called dense WDMs (DWDMs). Up to 32 channels will follow as users move to secure spacing on the ITUs 200-GHz, 1.6-nm and 100-GHz, 0.8-nm grids at the nominal 1,550-nm.
E-pHEMT	enhancement-mode pseudomorphic high-electron-mobility transistor
EDFA	erbium-doped fiber amplifier (1550nm)
ETDM	electrical time-division multiplexing
FBG	fiber Bragg gratings
FET	field effect transistor
HBT	hetero junction bipolar transistor
HEMT	high-electron-mobility transistor
LOIS	laser optoacoustic imaging system
LMDS	Local Multichannel Digital Service, Wireless cable service providing multiple channels of video programming over high-frequency microwave channels in the 27.5-29.5GHz spectrum. LDMS antennas serve overlapping cells of technology is likely to make LMDS an attractive broadband technology in the future.
MMDS	Multi-channel, Multi-point, Distribution Service, "wireless cable" broadcasting. Wireless cable technology using frequencies in the 2.5 - 2.7 GHz band. One antenna can serve line-of-site customers in a thirty-mile radius. Customers use a twelve-inch dish to receive the signal and require a set-top box to descramble it. MMDS is very popular in much of the developing world because of the relatively low cost of passing a large number of subscribers. While analog systems have been limited by a relatively small number of available channels, new digital systems utilizing mpeg-2 compression promise to increase dramatically the capacity and the attractiveness of this broadband technology.
SAW	surface acoustical wave
SIHBT	symmetrical intrinsic hetero-bipolar transistor
SNR	signal-to-noise ratio
SONET	Synchronous Optical NETwork, a set of standards for data communication over fiber optic cable at speeds between 51.84 Mbps and 13 Gbps.
TDM	time-division multiplexing
TFT	thin film transistor

		Deposition

SPUTTERING
In sputter deposition (commonly called 'sputtering'), material is removed, as atoms or molecules, from a solid target by energetic ion bombardment and deposited as atomic layers on a substrate. By applying a high RF or DC voltage between the target (cathode) and the substrate (anode), energetic electrons emitted from the target form ions in the process gas, typically argon at 1 to 100 mtorr pressure. Under these conditions, a plasma (an electrically neutral association of electrons and positive ions) is formed.

The applied electric field accelerates Ar+ ions from the plasma's edge into the target with kinetic energies up to several hundred eV. Energy transfer causes target atoms to eject with similar energies. Between target amd substrate, however, each ejected atom has numerous gas phase collisions with the process gas, which deflect it and lower its energy. By optimizing the distance between target and substrate, the approach angles of the target atoms to the substrate surface are so randomized that a uniform film results.

Sputter Deposition Benefits (advantages over evaporation techniques):

1. Higher kinetic energy of deposited atoms results in better film adhesion
2. More easily automated for in-line industrial processing
3. No 'spitting' occurs that would leave lumps of material on the substrate
4. Sputter source can be mounted in any orientation
5. Plasma is energetically hot, but has a small thermal capacity
6. Since coverage is independent of line-of-sight, sputtering inherently produces uniform film coatings over nonflat surfaces
7. Refractory materials, elements, mixtures and alloys can be sputtered with equal facility
8. Sputtering with O₂ (or N₂) in the argon process gas leaves the target unreacted, yet deposits an oxide (or nitride) film on the substrate.

Magnetron Sputtering

Torus Sources

Sources

• Single
• Cluster
• Platform

EVAPORATION
Evaporation occurs when a material's atoms/molecules achieve sufficient energy to overcome the solid/liquid's binding forces and enter the gas phase. To increase the evaporation rate, the average energy is increased by raising the material's temperature. Raising the material's temperature increases its vapor pressure (VP). Many think a solid either has no VP, or has a huge jump in VP when it melts. Neither is true! For all materials that do not decompose on heating, the VP vs. temperature curve is smooth, with the material's melting point having no effect at all. Successful evaporative coatings of many materials involve no liquefaction.

Liquefaction is no indication of VP. For example, mercury liquefies at 234K, at which temperature it has a VP of 2x10-6 torr. Gallium liquefies at 303K with an immeasurably low VP, and does not reach 2x10-6 torr until its temperature reaches 1040K.

In evaporation for thin film production, four heating techniques are commonly used:

• Direct resistive heating
  If the material is placed in a refractory metal boat through which a high current flows, the evaporation technique is direct resistive heating. The low equipment costs of this method is balanced by the difficulty of maintaining a constant evaporation rate compared to other techniques.
• Indirect resistive heating
  
• The material is placed in a crucible to isolate it from the heater filament. The increased thermal mass and the separation of the material and the heater wire/ribbon, stabilizes the evaporation rate. The names, Knudsen cell, K-cell, effusion source, are given to various incarnations of indirectly heated evaporation sources, but eh distinction between designs carrying these names is increasingly blurred.
• e-beam evaporation
  
• For electron beam evaporation, a high electron flux (generated by thermionic emission at a filament) is extracted and magnetically bent/focused into the top of the crucible containg the material.
• Laser ablation
  If the material is struck by a laser beam of sufficient power density, appropriate wavelength to be absorbed (rather than reflected), and appropriate angle of incidence, the material ablates giving a plume of vapor.

MOLECULAR BEAM EPITAXY (MBE)
The intrinsic features of MBE make it possible to very accurately control the structure parameters, such as layer thickness, doping and composition profiles. Surface growth is typically characterized by dynamics far from equilibrium, i.e., the deposition rate is sufficiently large so that the surface does not relax through surface diffusion to a state of thermal equilibrium between successive deposition events.

CHEMICAL VAPOR DEPOSITION (CVD)

Metal organo CVD