Cleaning and liquid contact with solids – Processes – Using sequentially applied treating agents
Reexamination Certificate
2000-12-22
2004-06-01
Kornakov, M. (Department: 1746)
Cleaning and liquid contact with solids
Processes
Using sequentially applied treating agents
C134S001000, C134S002000, C134S003000, C134S019000, C134S030000, C134S032000, C134S033000
Reexamination Certificate
active
06743301
ABSTRACT:
BACKGROUND OF THE INVENTION
a) Field of the Invention
This invention relates to a process and apparatus for treating a variety of substrates—such as wafers, glass substrates or ceramic substrates for forming semiconductor devices thereon (hereinafter called “substrates”)—by cleaning off, subsequent to formation of a fine arrangement of electrical component parts or a circuit (hereinafter may be commonly called “pattern”) on the substrates, foreign matter such as organic matter remaining on the substrates and other foreign matter adhered during or after the formation of the pattern.
The term “ozone water” as used herein means water which is available by dissolving an ozone-containing gas in ultrapure water. The term “hydrogen water” as used herein means water which is available by dissolving a hydrogen-containing gas in ultrapure water. Further, the term “ozone-hydrogen water” as used herein means water which is available by dissolving an ozone-containing gas and a hydrogen-containing gas in ultrapure water or by mixing ozone water and hydrogen water.
b) Description of the Related Art
When forming a pattern on a substrate, an organic material such as a photoresist (hereinafter called a “resist”) is coated on the substrate, exposed and then developed to form a desired resist pattern, and the substrate is thereafter subjected to treatment such as etching at a surface thereof. Subsequent to this treatment, any unnecessary resist on the substrate is removed.
After the removal of the resist, it is necessary to clean off very small pieces of the resist, said pieces still remaining on the substrate, and other foreign matter adhered during or subsequent to the formation of the pattern. Conventional cleaning processes for this purpose are classified into wet processes or dry processes depending on the kinds and properties of the resists and the forming steps of component parts.
In the wet processes, a chemical solution which contains sulfuric acid, hydrogen peroxide or the like as a principal component and has oxidizing power is used in many instances (SPM treatment). In the dry processes, on the other hand, organic matter or the like on a substrate is removed by ashing the same while using oxygen as a primary process gas. Depending on the state of contamination of a substrate, cleaning treatment is also performed making appropriately combined use of ashing treatment with oxygen plasma, SPM treatment, and treatment with a chemical solution containing ammonia and hydrogen peroxide or the like as principal components (APM treatment).
As illustrative conventional techniques for such treatment of substrates, JP 10-298589 A discloses a process in which subsequent to plasma ashing of a resist, organic matter and the like on a substrate are removed using ozone water with a basic fluoride added therein. A process is proposed in JP 9-255998 A, in which ultraviolet rays are irradiated in the presence of ozone gas to remove fine organic particles which are remaining on a substrate. JP 10-41262 A discloses to use carbonated water or hydrogen water, which has been prepared by dissolving hydrogen gas in ultrapure water, for the removal of fine metal particles while minimizing corrosion of a pattern such as metalization, i.e., a deposited film pattern of a conductor material. Further, it is proposed in JP 10-128253 A to clean and rinse a substrate under exposure to supersonic waves in hydrogen water which has been prepared by dissolving hydrogen gas to a concentration of 0.05 ppm or higher in ultrapure water.
The cleaning with ozone water subsequent to ashing as disclosed in JP 10-298589 A involves a potential problem in that a substrate may be damaged as the plasma ashing is performed with high energy, and the cleaning treatment with the ozone water is accompanied by a further potential problem in that the damage may be deteriorated. In addition, surface roughening may also occur by a cause other than the plasma ashing, and the cleaning with the ozone water has a potential problem in that damage may be spread from such surface roughening. The process disclosed in JP 9-255998 A, in which ultraviolet rays are irradiated in the presence of ozone, is intended for fine organic particles, and cannot be applied for stripping a resist. The cleaning with ozone water, which is disclosed in JP 10-41262 A, is intended to remove fine metal particles, and the effect of the ozone water depends upon the concentration of ozone contained in the ozone water. The concentration of ozone in conventional ozone water, which is available at room temperature under the surrounding atmospheric pressure, is its saturated concentration at the maximum, and therefore, this cleaning process is not considered to be effective for the removal of organic matter still remaining after dry ashing of a resist. Further, the process disclosed in JP 10-128253 A, in which a substrate is soaked in hydrogen water prepared by dissolving hydrogen gas to a concentration of 0.05 ppm or higher in ultrapure water and is exposed to ultrasonic waves, relates to rinsing treatment, and this patent publication makes no mention about the removal of a residue of a resist after dry ashing of the resist.
Of these conventional processes, the wet processes use one or more chemicals such as sulfuric acid, hydrogen peroxide and/or ammonia upon treatment, and may develop one or more defects in a formed pattern due to formation of sulfuric acid vapor, which gives detrimental effects such as corrosion to a substrate, or due to incorporation of a metal component such as iron due to the use of ammonia. Avoidance of these problems leads to a further problem that subsequent to the treatment, a great deal of cleaning water is needed, resulting in a substantial load of effluent on the environment. On the other hand, the use of oxygen plasma in the dry processes involves a problem in that a substrate, which is chemically sensitive, and a pattern formed on the substrate may be damaged because the plasma has high energy.
SUMMARY OF THE INVENTION
An object of the present invention is, therefore, to provide a substrate treatment process and apparatus, which can achieve similar cleaning effects as the conventional techniques without needing use of sulfuric acid, hydrogen peroxide, ammonia, oxygen plasma and/or the like as an essential requirement and without causing production of harmful vapor, incorporation of a metal component such as iron, damage to a substrate, a pollutant load on the environment, or the like.
The above-described object can be achieved by the present invention. In one aspect of the present invention, there is thus provided a substrate treatment process for removing organic matter existing on a substrate, which comprises the following consecutive steps:
treating said substrate with ozone water which has been prepared by dissolving an ozone-containing gas in ultrapure water; and
treating said substrate with hydrogen water which has been prepared by dissolving a hydrogen-containing gas in ultrapure water.
In another aspect of the present invention, there is also provided a substrate treatment process for removing organic matter existing on a substrate, which comprises the following step:
treating said substrate with ozone-hydrogen water, which has been prepared by dissolving an ozone-containing gas and a hydrogen-containing gas in ultrapure water, or with ozone-hydrogen water prepared by mixing ozone water, which was in turn prepared by dissolving an ozone-containing gas in ultrapure water, and hydrogen water which was in turn prepared by dissolving a hydrogen-containing gas in ultrapure water; or treating said substrate with said ozone water and said hydrogen water at the same time.
In a further aspect of the present invention, there is also provided a substrate treatment apparatus for a substrate, comprising:
a treatment vessel,
a substrate holder for rotating said substrate in a horizontal plane in said treatment vessel,
a nozzle unit arranged in an upper part of said treatment vessel such that a liquid is downwardly fed,
a feed line for feeding the liquid t
Iga Masao
Matsuno Kousaku
Kornakov M.
m&Circlesolid;FSI Ltd.
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
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