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Browse Prior Art Database

Liquid HF Etching Without Contamination

IP.com Disclosure Number: IPCOM000089242D
Original Publication Date: 1977-Oct-01
Included in the Prior Art Database: 2005-Mar-04
Document File: 2 page(s) / 46K

Publishing Venue

IBM

Related People

Beyer, KD: AUTHOR [+2]

Abstract

The following silicon cleaning process produces cleaned wafers with the lowest possible surface contamination: 1. Dip the silicon wafer into an HF concentration solution for 5 minutes. 2. Deionize (D.I.) H(2)O rinse and spin dry. 3. HF/H(2)O vapor etch for 1 minute over 49% HF. After vapor etching, immediate immersion into cleaning solution of HCl (37% concentrated in H(2)O) at room temperature. 4. D.I. H(2)O rinse. 5. Ultrasonically clean wafer in NH(4)OH, H(2)O(2), H(2)O solution at 60 Degrees C. 6. D.I. H(2)O rinse. 7. Ultrasonically clean wafer in HCL, H(2)O(2), H(2)O solution at 60 Degrees C. 8. D. I. H(2)O rinse.

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Liquid HF Etching Without Contamination

The following silicon cleaning process produces cleaned wafers with the lowest possible surface contamination: 1. Dip the silicon wafer into an HF concentration solution for 5 minutes. 2. Deionize (D.I.) H(2)O rinse and spin dry.
3. HF/H(2)O vapor etch for 1 minute over 49% HF. After vapor etching, immediate immersion into cleaning solution of HCl (37% concentrated in H(2)O) at room temperature. 4. D.I. H(2)O rinse. 5. Ultrasonically clean wafer in NH(4)OH, H(2)O(2), H(2)O solution at 60 Degrees C. 6. D.I. H(2)O rinse. 7. Ultrasonically clean wafer in HCL, H(2)O(2), H(2)O solution at 60 Degrees C. 8.
D. I. H(2)O rinse.

The model for the HF (liquid)/D.I. H(2)O/HF (vapor)/HCl cleaning process sequence may be understood with reference to the drawing and the following points: 1. In silicon wafers, impurities such as copper and gold, etc., have the normal distribution curve with an impurity concentration peak near the silicon surface C1 shown in the drawing. 2. During the "liquid" HF dip, a thin surface layer of silicon is removed. The impurity surface concentration is thereby reduced from the original level C1 to a new surface concentration C2 according to the drawing. This new surface concentration C2 is lower than the original one, C1, because the impurity level decreases with increasing silicon depth. But, during "liquid" HF-etching, metallic impurities, originating from metallic contamination of the HF solution and from the...