Dismiss
InnovationQ will be updated on Sunday, Oct. 22, from 10am ET - noon. You may experience brief service interruptions during that time.
Browse Prior Art Database

DEFECT DENSITY EVALUATION METHOD

IP.com Disclosure Number: IPCOM000005775D
Original Publication Date: 1989-Aug-01
Included in the Prior Art Database: 2001-Nov-05
Document File: 1 page(s) / 51K

Publishing Venue

Motorola

Related People

David Rodgers: AUTHOR [+2]

Abstract

In evaluating the defect density.of epitaxial layers, it is desirable to determine a focal point on the wafer surface as well as accurately defining a known unit of area in which defect density may be calculated. Prior art methods of measuring defect density have included using epitaxial defects and surface particulates as a focal point and then employing the objective lens field of view to determine area. Another prior art method in- cludes employing a template of lint-free paper having a cutout of known area and disposing the template on the surface of a wafer and counting defects within the cutout. However, this method generates particles and also requires that epitaxial defects be employed as focal points.

This text was extracted from a PDF file.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 91% of the total text.

Page 1 of 1

MOlVROLA Technical Developments Volume 9 August 1989

DEFECT DENSITY EVALUATION METHOD

by David Rodgers and Jim Kirchgessner

   In evaluating the defect density.of epitaxial layers, it is desirable to determine a focal point on the wafer surface as well as accurately defining a known unit of area in which defect density may be calculated. Prior art methods of measuring defect density have included using epitaxial defects and surface particulates as a focal point and then employing the objective lens field of view to determine area. Another prior art method in- cludes employing a template of lint-free paper having a cutout of known area and disposing the template on the surface of a wafer and counting defects within the cutout. However, this method generates particles and also requires that epitaxial defects be employed as focal points.

   It is proposed that a laser marking system, preferably having soft mark capability, be employed to pattern an epitaxial wafer surface with regions of a known area. The laser marks provide an easily used focal point and the defined pattern delineates a region of known area for defect density calculations. The disclosed method enables the collection of defect density data using aconsistent inspection areadefined on a wafer while further enabling uniform focus on the epitaxial wafer surface.

Figure 1

Figure 2

(Stmulatton: High power inspection of softmark area)

(Simulation of softmarked waler)

Wafer Softmark squares

Softmarked overlapping...