Semiconductor manufacturing system

Abstract

Disclosed is a technique for effectively suppressing the generation of particles resulting from peeling-off of unnecessary films that have unavoidably adhered to the inner surface of the reaction tube of an ALD film-forming apparatus. A precoating process utilizing ALD is performed to deposit a metal oxide film, e.g., an aluminum oxide film, onto the unnecessary films, in order to prevent peeling-off of the unnecessary films. The type and / or position of the nozzle for supplying ozone, as a precoat gas, into the reaction tube during the precoating process is different from that of the nozzle for supplying ozone, as a film-forming gas, into the reaction tube during forming of a film on a semiconductor substrate.

Description

TECHNICAL FIELD [0001] The present invention relates to semiconductor manufacturing system and particularly to coating apparatus for forming a film of a desired thickness by repeating atomic or molecular level deposition. More particularly, the Invention relates to a technique of effectively precoating the inside of the reaction vessel to prevent the generation of particles. BACKGROUND ART [0002] With higher integration of semiconductor devices, the miniaturization of their device pattern progresses. For example, 1-gigabit dynamic random access memory (DRAM) has been used in practical applications. Such large capacity DRAM employs elements reduced in dimension and hence in surface area. Since DRAM uses the amount of charge stored on its memory cell capacitors as stored information, these capacitors must have a capacitance greater than a certain value. Therefore, memory cell capacitors currently have a very high aspect ratio. Conventionally, CVD (Chemical Vapor Deposition) is used to...

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Benefits of technology

[0013] The present invention has been devised in view of the foregoing circumstances, and it is therefore the object of the present invention to provide an effective, in-situ method of taking countermeasure against particles.

[0014] The present inventors have found that, also in a coating apparatus that forms a film on semiconductor substrates by repeated atomic or molecular level depositions, a precoating process that coats unnecessary film(s) with another film is useful for reducing particles. It has also been found that such a precoating process can be performed very effectively, if the gas supply mode during precoating is different from the gas supply mode during film formation, in particular, if a gas nozzle for a precoating gas is provided separately from a gas nozzle for film formation. The present invention has been made based on those findings.

[0019] In the most typical embodiment of the present invention described later with reference to the accompanying drawings, the first film-forming gas is ozone; the second film-forming gas is TEMAH gas; the third film-forming gas is trimethyl aluminum (hereinafter abbreviated as “TMA”) gas; the first precoating gas is ozone; and the second precoating gas is TMA gas. Further, the semiconductor manufacturing system is a vertical, batch-type system that accommodates a plurality of semiconductor substrates arrayed vertically in horizontal posture in the reaction vessel, and performs a film-forming process to the semiconductor substrates collectively. Further, the film-forming nozzle for supplying the first film-forming gas (i.e., ozone) is a distributing nozzle having a plurality of nozzle holes for discharging the first film-forming gas toward the plurality of semiconductor substrates from their sides; and the coating nozzle for supplying the first coating gas (i.e., ozone) is an L-shaped nozzle having a nozzle hole which opens in the reaction vessel at a position farther from an exhaust port than a region in which the plurality of semiconductor devices are disposed. Ozone is a short-lived gas. Such a gas is supplied through the distributing nozzle during film formation, but is supplied from a position far away from the exhaust port during precoating so that the gas uniformly spreads within the vessel. Thereby, a film of high quality can be obtained during film formation, while the entire inside of the reaction vessel can be coated with a precoat film of high quality with a small number of deposition cycles during precoating. In this way, it is possible to effectively prevent generation of particles, and the system can restart in a short time period after maintenance of the system.

Problems solved by technology

However, it is difficult by CVD to uniformly form a dielectric film in a high aspect ratio groove with a high coverage.

ALD is advantageous in its excellent film-thickness reproducibility, but is disadvantageous in its long film-forming time.

On the other hand, ozone has a short life under elevated temperature conditions.

However, the supply of an excessive amount of ozone causes oxidation damage to the components in the lower portion of the reaction chamber 1101, which is not desirable.

Furthermore, ozone is consumed by this oxidation reaction.

Incidentally, particle reduction is a critical issue in semiconductor manufacturing.

When a film is formed on the semiconductor substrates by CVD, ALD, or other chemical deposition process, deposition of unnecessary films unavoidably occurs on the inner wall of the reaction tube and on the various components that are exposed to the atmosphere within the reaction vessel.

Peeling-off of the unnecessary films is a major cause of the generation of particles, as is well known to those of ordinary skill in the art.

Peeling-off of the unnecessary films tends to occur when the unnecessary films have a large thickness or when the inside of the reaction vessel is exposed to the ambient atmosphere.

It was not possible to visually recognize the HfO particles since their sizes were very small (mostly 10 microns or less).

Under such conditions, a deposition process can not be performed.

However, there is no established method for removing an HfO film by in-situ dry cleaning.

Wet cleaning, on the other hand, requires disassembly of the system, resulting in significant downtime.

Furthermore, wet cleaning should not be frequently performed, since it shortens the life of the quartz components.

Replacement of components results in shorter downtime.

However, it is not practical since quartz components are expensive.

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