Cleaning and liquid contact with solids – Processes – For metallic – siliceous – or calcareous basework – including...
Patent
1997-05-14
1999-03-23
Alexander, Lyle A.
Cleaning and liquid contact with solids
Processes
For metallic, siliceous, or calcareous basework, including...
134 38, 134 40, 134 42, C03L 2300
Patent
active
058853626
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a surface treatment composition and a method for treating the surface of a substrate using the same. More particularly, the present invention relates to a surface treatment composition comprising a liquid medium as the main component, which prevents a substrate surface from being contaminated with metal impurities from the surface treatment composition and stably provides an extremely clean substrate surface, and also relates to a method for treating the surface of a substrate by using the same. Further, the present invention relates to a method for supplying components for the surface treatment composition and a method for purifying a complexing agent used for the composition.
BACKGROUND ART
In accordance with high integration of various devices represented by VLSI, TFT liquid crystals and the like, cleanliness levels of substrate surfaces used for these devices are demanded to be higher and higher. Contaminations with various materials disturb to achieve higher cleanliness, and among the contaminations, a metallic contamination particularly deteriorates electric properties of a device, and it is therefore necessary to utmostly lower a metal impurity concentration on a substrate surface for forming a device in order to prevent the above-mentioned deterioration. For this purpose, it is generally conducted to clean a substrate surface with a cleaning agent.
Heretofore, for this type cleaning agent, there are generally used water, electrolyzed ionic water, acid, alkali, oxidizing agent, surfactant aqueous solution or organic solvents and the like. The cleaning agent is demanded not only to have excellent cleaning performances but also to have an impurity concentration of such an extremely low level as to prevent a substrate from being contaminated with a metal impurity from the cleaning agent. In order to satisfy these demands, cleaning chemicals for semiconductors are highly purified, and a metal impurity concentration in the chemicals immediately after purification reaches a level of hardly detectable by present analytical techniques.
Although an impurity in a cleaning agent is lowered to such a low level as to be hardly detectable, it is still difficult to provide a highly clean substrate surface. This is because it can not be avoided that a cleaning agent itself is contaminated with a metal impurity removed from a substrate in a cleaning tank. Thus, a metal impurity separated from a metal surface is incorporated into a cleaning agent and the metal impurity in the contaminated cleaning agent is then deposited on a substrate (reverse contamination).
In a step of cleaning semiconductors, cleaning (SC-1 cleaning) with "ammonia+hydrogen peroxide+water" solution is widely used (see RCA Review, p 187-206, June (1970) etc.). This cleaning is usually conducted at 40.degree.-90.degree. C., and the composition ratio of a cleaning solution usually used is (30 wt % aqueous ammonia):(31 wt % hydrogen peroxide):(water)=0.05:1:5 to 1:1:5. However, this cleaning method has high performances to efficiently remove particles and organic materials, but when metals such as Fe, Al, Zn and Ni are present even in a very small amount in the solution, they are deposited on a substrate surface, thus raising a problem of reverse contamination. For this purpose, in the step of cleaning semiconductors, after cleaning with "ammonia+hydrogen peroxide+water" solution, cleaning with an acid cleaning agent such as "hydrochloric acid+hydrogen peroxide+water" solution (SC-2 cleaning) is usually conducted to remove metal contamination on a substrate surface.
Therefore, in the cleaning step, a technique to prevent the reverse contamination has been demanded in order to stably and efficiently provide a highly clean surface.
Further, a problem of deposition of metal impurities in a liquid onto a substrate surface is generally a large problem not only in the cleaning step but also in substrate surface treatment steps using a solution such as an alkali etching step of a silicon substrate, an etc
REFERENCES:
patent: 5498511 (1996-03-01), Yamashita et al.
Fujisue Masaya
Morinaga Hitoshi
Alexander Lyle A.
Mitsubishi Chemical Corporation
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