Cleaning compositions for solid surfaces – auxiliary compositions – Cleaning compositions or processes of preparing – For cleaning a specific substrate or removing a specific...
Patent
1996-07-24
1998-06-09
Richter, Johann
Cleaning compositions for solid surfaces, auxiliary compositions
Cleaning compositions or processes of preparing
For cleaning a specific substrate or removing a specific...
510176, 510204, 510206, 510209, C11D 708, C11D 728, C11D 732, H01L 21304
Patent
active
057633754
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to cleaning agents and a cleaning method, for example, for use in processes for producing semiconductor devices for cleaning the surfaces of semiconductor substrates such as silicon wafers. More particularly, the invention relates to cleaning agents and a cleaning method which are highly effective for preventing the contamination of the surfaces of silicon wafers and the like with fine particles. Further more particularly, the invention relates to cleaning agents and a cleaning method for removing a native oxide film, usually about 10 angstroms in thickness, from the surfaces of silicon wafers and the like, and for preventing the contamination of cleaning solutions due to the presence of fine particles therein.
BACKGROUND ART
In processes for producing semiconductor integrated circuit devices wherein LSIs are formed on semiconductor substrates (wafer) comprising a single crystal of silicon, a wet cleaning treatment is conducted with use of various chemical solutions to remove organic substances, metal or like fine particles and a native oxide film from the substrate surfaces. Generally used as chemical solutions for the wet cleaning treatment are, for example, those comprising a sulfuric acid (H.sub.2 SO.sub.4)--hydrogen peroxide (H.sub.2 O.sub.2) aqueous solution, hydrochloric acid (HCl)--hydrogen peroxide (H.sub.2 O.sub.2) aqueous solution or hydrofluoric acid (HF)--hydrogen peroxide (H.sub.2 O.sub.2) aqueous solution, hydrofluoric acid (HF)--nitric acid (HNO.sub.3)--acetic acid (CH.sub.3 COOH) aqueous solution, ammonia (NH.sub.4 OH)--hydrogen peroxide (H.sub.2 O.sub.2) aqueous solution, or aqueous solution of hydrofluoric acid. However, particles are very prone to adhere to the substrate surface after the native oxide film is removed by the wet cleaning treatment especially when solutions of hydrofluoric acid or a mixture containing the acid is used. The particles adhering to the substrate surface cause short-circuiting of the wiring or other fault, directly impairing the yield of semiconductor integrated circuit devices as products, so that the number of adhering particles must be minimized. The adhesion of particles to the substrate surface is conventionally prevented, for example, by circulating the cleaning solution through a membrane filter having a pore size of about 0.1 micrometer and thereby minimizing the number of particles present in the solution.
With integrated circuits made available with a finer pattern, the cleaning solution is required to have higher cleanliness, whereas the number of extraneous particles brought into the cleaning bath tends to rather increase owing to an increase in the number of wafer processing steps or in the diameter of wafers.
In view of the situation described, JP-A-53083/1991, for example, discloses a method of preventing metallic contamination of semiconductor devices which is characterized by adding an anionic surfactant of short molecular length with 5 to 8 carbon atoms to an aqueous solution of hydrofluoric acid or the like. However, the surfactants mentioned for use in this method are only carboxylic acids or sulfonic acids represented by CxHyCOOH, CxHySO.sub.3 H, CxFyCOOH or CxFySO.sub.3 H (wherein x is an integer of 4 to 7, and y is an integer of 9 to 15), or salts thereof, and the publication contains no further description in greater detail and mentions nothing about the salts. Merely listed in Table 2 of the publication are carboxylic acids or sulfonic acids with 5 to 7 carbon atoms as the acids used in the examples. Although no generalized description is given as to the concentration of hydrofluoric acid and the like for use in the method, an acid of considerably high concentration, such as 6% HF or 5% HF, is used in the examples.
JP-A-138142/1993 describes a technique concerning a method of controlling adhesion of fine particles in a solution which method is characterized in that a substance capable of controlling the zeta potential (surface potential) of the fine particles is added to the solution at
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Ohmi et al., J. Electrochem. Soc., vol. 140, No. 3, Mar. 1993, pp. 811-818.
Itano Mitsushi
Kezuka Takehiko
Kubo Motonobu
Daikin Industries Ltd.
Qazi Sabiha N.
Richter Johann
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