Compositions – Etching or brightening compositions
Patent
1998-04-22
2000-05-30
Garrett, Felisa
Compositions
Etching or brightening compositions
252 792, 252 793, 252 794, 438745, C09K 1304, C09K 1306
Patent
active
060687886
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a treating solution of silicon wafers and a method for preparing the solution. More particularly, the invention relates to a treating solution of silicon wafers which prevents the contamination of the surfaces of the silicon wafers with fine particles, and to a method for preparing the solution.
BACKGROUND ART
In the manufacturing steps of semiconductor integrated circuit devices in which an LSI is formed on a semiconductor substrate (wafer) comprised of a single crystal of silicon, a wet etching using a hydrofluoric acid (HF) solution is employed in patterning an oxide film (SiO.sub.2) of the surface of a substrate or in removing a native oxide film that is formed on the surface of the substrate in heat treatment. An etching of the surface of SiO.sub.2 is made by using a hydrofluoric acid (HF) aqueous solution or a buffered hydrofluoric acid aqueous solution (HF--NH.sub.4 F--H.sub.2 O). An etching of Si.sub.3 N.sub.4 is made by using a phosphoric acid (H.sub.3 PO.sub.4) aqueous solution. An etching of the surface of Si is made by using a hydrofluoric acid (HF)-nitric acid (HNO.sub.3) aqueous solution or a hydrofluoric acid (HF)-nitric acid (HNO.sub.3)-acetic acid (CH.sub.3 COOH) aqueous solution. When removing a metal adhered to the surface of a substrate in wiring forming steps or the like, a wet cleaning is made by using a hydrofluoric acid (HF) aqueous solution, a hydrofluoric acid (HF)-hydrogen peroxide (H.sub.2 O.sub.2) aqueous solution, or a hydrochloric acid (HCl)-hydrogen peroxide (H.sub.2 O.sub.2) aqueous solution. In these wet cleanings, in order to prevent extraneous particles from adhering to the active surface of a substrate after removing the above-mentioned oxide film or metal, it is necessary to retain the cleanliness of an etchant or a cleaning solution by, for example, circulating and filtrating the etchant or cleaning solution.
Meanwhile, such an etchant or cleaning solution is required to have a higher cleanliness as the refinement of integrated circuits is progressed. However, extraneous particles brought into a treating bath tend to increase with increasing wafer process and wafer aperture.
Although techniques of adding a surfactant into the aforementioned treating solutions have been developed, each method has the following problem. That is, even if a surfactant is dissolved until it reaches the saturated solubility, in a high concentration of HF, H.sub.2 O.sub.2, HNO.sub.3, CH.sub.3 COOH, NH.sub.4 F, HCl, H.sub.3 PO.sub.4, or an ammonium hydroxide represented by the formula [(R.sub.1)(R.sub.2)(R.sub.3) (R.sub.4)N].sup.+ OH.sup.- (R.sub.1, R.sub.2, R.sub.3 and R.sub.4 are an alkyl group having 1 to 6 carbon atoms which may have a hydroxyl group as a substituent), when it is diluted or mixed with other chemical, the surfactant is thinned and thus fails to obtain the effect of reducing particle adhesion. In the cases where a surfactant is diluted or is added when mixing with other chemical, there are problems that much time is required and, in order to obtain a sufficient reduction effect of particle adhesion, it is necessary to add a large quantities of surfactant, causing severe foaming.
From the viewpoints as stated, the present inventors proposed a method for preventing the contamination of the surfaces of silicon wafers with fine particles by treating with a solution prepared by adding an anionic surfactant or a nonionic surfactant into a low concentration of hydrofluoric acid or the like (JP-A-41770/1994). However, this method was poor in storage and transport efficiencies. It was also unknown whether surfactants disclosed in this publication are dissolved in a high concentration into a high-level hydrofluoric acid.
Accordingly, it is an object of the present invention to provide a wafer treating solution having the following features. Specifically, when in cleaning or etching the surfaces of wafer, a specific surfactant is contained in a high concentration of HF, H.sub.2 O.sub.2, HNO.sub.3, CH.sub.3 COOH, NH.sub.4 F, HCl, H.s
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English Abstract of JP-A-6-041,770--Kezuka et al.
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English Abstract of JP-A-6-084-866--Saito et al.
Itano Mitsushi
Kamiya Fumihiro
Kezuka Takehiko
Suyama Makoto
Daikin Industries Ltd.
Garrett Felisa
Umez-Eronini Lynette T.
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