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Improvements to Surface Characteristics of Silicon Wafers

IP.com Disclosure Number: IPCOM000042486D
Original Publication Date: 1984-May-01
Included in the Prior Art Database: 2005-Feb-03
Document File: 2 page(s) / 33K

Publishing Venue

IBM

Related People

Cazcarra, V: AUTHOR [+2]

Abstract

Surface characteristics of silicon wafers are greatly improved with hydrophilic cleaning. Each wafer supplier has his own process to clean wafers after the various operations (polishing, visual inspection, etc.) completed in the wafer facility. According to these cleaning sequences, the surface of the silicon wafer can be either hydrophilic or hydrophobic. These two characteristics are measured with the "water drop test". The need for processing only hydrophilic wafers will be demonstrated below. After a reactive etch operation, e.g., etching of the surface with a HNO3,HF mixture which is the first step in a semiconductor manufacturing line, an hydrophobic wafer will present etching traces and haze, unlike a hydrophilic wafer which will be uniformly etched.

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Improvements to Surface Characteristics of Silicon Wafers

Surface characteristics of silicon wafers are greatly improved with hydrophilic cleaning. Each wafer supplier has his own process to clean wafers after the various operations (polishing, visual inspection, etc.) completed in the wafer facility. According to these cleaning sequences, the surface of the silicon wafer can be either hydrophilic or hydrophobic. These two characteristics are measured with the "water drop test". The need for processing only hydrophilic wafers will be demonstrated below. After a reactive etch operation, e.g., etching of the surface with a HNO3,HF mixture which is the first step in a semiconductor manufacturing line, an hydrophobic wafer will present etching traces and haze, unlike a hydrophilic wafer which will be uniformly etched. In the same way, if both hydrophilic and hydrophobic wafers are dipped in DI water slightly contaminated by silica, and then dried, the hydrophilic one will come out clean (i.e., it presents no particles) while the hydrophobic one will present a haze (i.e., it presents a large number of particles) after visual inspection. The figure shows the evolution of the contamination of the different kinds of wafers. If the superficial tension on the wafers is measured, it can be seen with an automatic inspection tool that there are many more particles per surface unit after a DI water rinse or a cleaning operation on an hydrophobic wafer (see supplier 1) than on...