In order to remain cost competitive, VLSI and ULSI technologies have been incorporating ever increasing device densities within their structures. Accordingly, the technology of producing such semiconductor devices has been continually pressured to fabricate individual devices which occupy decreased surface area and yet which provide at least the same level of reliability. For example, reduction of the surface area utilized by storage capacitors has been achieved by incorporating a three-dimensional design in the vertical dimension (e.g. fingered structures) upon which may be utilized ultrathin capacitor dielectric materials, typically a silicon oxide or silicon oxynitride material. Accordingly, this continuous shrinking of device structures and the use of more complex device structures has likewise made it desirable to use superior (and thereby thinner) gate oxides, passivation layers and dielectric layers. Accordingly, there exists a need for tools capable of making superior oxide films which retain desired characteristics, such as high V.sub.BD (Voltage breakdown strength represents the amount of voltage which can be placed across an insulator before a significant amount of electrons begin to pass therethrough) and a high uniformity and reliability relative to that of thicker films.
Production of high quality thin films on a silicon surface requires a "clean" silicon surface. However, silicon surfaces may pick up contaminants in numerous ways. For example, when silicon is exposed to even mild oxidants, e.g. H.sub.2 O, a "nascent" oxide is naturally formed on the silicon surface. Therefore, exposure of the silicon substrate to common oxidants, such as those found in the ambient atmosphere, tends to contaminate the silicon surface and prevent formation of a high quality film thereon. In addition to common oxidants, airborne bacteria may become situated on the silicon substrate thereby preventing the effective formation of a high quality film. Similarly, particulate contaminants naturally found within the atmosphere may likewise become situated on the silicon substrate thereby degrading the resulting uniformity and V.sub.BD of a film formed on the silicon substrate.
Contaminants commonly find their way into reaction chambers of semiconductor processing devices in numerous ways, such as via plumbing, valves and junctions. Contaminants may often be found within the bottled air supplies themselves or may enter the air supply (intended for the processing chamber) upon hooking-up or changing of air supply bottles and tanks. Moreover, the tubing or plumbing utilized to connect gas supplies with the processing chamber may itself become a source of contaminants. For example, bacteria once having entered the plumbing, may become attached thereto and begin to grow, thereby creating a continuous and increasing source of organic contaminants. Similarly, due to changes in humidity and temperature it is also possible to get condensation within the plumbing. Therefore, there exists a need for a processing tool capable of reducing the level of contaminants introduced into the processing chamber while still permitting introduction of an ultrapure gas, such as oxygen, into the processing chamber.
USPTO Backgrounds
USPTO Backgrounds