The level of purity, or the relative lack of contamination, affects the quality of the oxide layer or annealed surface.
However, steam may also contain other molecules such as metals, urea, volatiles, chlorine, particles, microdroplets, and organics in reality.
This requires intervention through the use of filters, selective membranes or other techniques to clean the water or steam before delivery to process.
Because water molecules form hydroxyl structures, they diffuse faster in silicon dioxide and the oxide growth rate increases.
Annealing and passivation are techniques used to repair atomic defects within the crystal that propagate into the wafer macrostructure, reducing efficiencies in microelectronics and photovoltaic cells.
Passivation, or thermal annealing, of the interface limits hole/electron recombination, removes dangling bonds, and reduces vacancies and dislocations at grain boundaries.
Annealing typically involves heating the wafer and saturating the chamber with a gas or water vapor that can then be incorporated into the film.
The steam readily inserts H and O atoms into the Si/SiO2 interface, and is much faster than FGA and comparable to the HRA process.
[5] An effective passivation of the rear surface of industrial solar cells is a prerequisite to considerably improve the conversion efficiency.
Water vapor plays an important role in deposition processes, as well as in annealing, release etching and bonding.
Water vapor can be the source of oxygen for the generation of oxides as well as a humidifier for dry gases in sputtering, spin-on and ALD processes.
In the semiconductor and MEMS industries, Rapid Thermal Processing (RTP) and Diffusion need high flow rates of water vapor for short periods of time.
Atomic layer deposition (ALD) depends on very small amounts of water vapor for High-K film formation.
Impurities in the water such as dissolved gases and ionic salts can change the index of refraction, which directly affects image quality projected onto the wafer.
[7] The technology required to improve CNT growth rate and uniformity faces major hurdles in its transfer from research to production.
For repeatable and reliable CNT fabrication, tools are needed to control whether CNTs are single or multi-wall, straight or bent, long or short, and clean or dirty.
[9] Water vapor has been shown to have significant effect on thin film layers in ALD, MOCVD, and sputtering processes for the manufacture of photovoltaics.
Such processes are commonly used to generate TCO layers and modify crystal structures via grain size or defect repair.
Purity can be achieved by blending pure gases under high heat or by purifying water vapor as it is generated.
In either case, the piping and instrumentation must be carefully chosen to avoid adding metals, particles or other contaminants back into the water vapor.
As an ingredient in industrial manufacturing processes, the steam must be generated and delivered at a consistent, controllable flow rate and have an extremely low contamination level.
The combustion process occurs either in a stainless steel catalytic oven or on a silicon torch at the entrance to the furnace.
The torch tip is typically quartz silica, which is known to be consumed over time by the flame, which may generate particulate downstream.
To use pyrolytic steam, the facility must install hydrogen and oxygen supply lines or store and dispose of gas cylinders.
The bubbling process is a single stage distillation step that concentrates contaminants in the remaining water in the vessel.
The effect of bubbling oxygen through clean water and kept warm by heating and incident IR leads to ideal conditions for growing bacteria.
In addition, the water is aggressive and can corrode the vaporizer internal components, leading to long term stability and reliability issues.
DLI offers a low operating cost, good flow control and limited safety issues.
DLI can vaporize only limited quantities due to thermal transfer rates, and there is a potential for chemical decomposition.
Once molecules cross the wall of the membrane, they are energized and ready to enter the gas phase based solely on the vapor pressure curve that relates to the temperature of the water.