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SEMI M25-95 © SEMI 1995, 2003 1 SEMI M25-95 (Withdrawn 1103) SPECIFICATION FOR SILICON WA FERS FOR CALIBRATION OF LIGHT POINT DEFECT WAFER INSPECTION SYSTEMS WITH RESPECT TO THE DIAMETER OF POLYSTYRENE LATEX SPHERES NOTI…

SEMI M24-1103 © SEMI 1994, 2003 18

requested for monitor test wafers. In actual business, an additional specification of LLS, the size of which is around CD is used, however, the size

is not standardized. TF proposes the additional LLS size as the same size as CD. This size is used for specifying LLS for Furnace & Thermal

Process Wafers.

NOTICE: SEMI makes no warranties or representations as to the suitability of the standards set forth herein for any

particular application. The determination of the suitability of the standard is solely the responsibility of the user.

Users are cautioned to refer to manufacturer's instructions, product labels, product data sheets, and other relevant

literature respecting any materials or equipment mentioned herein. These standards are subject to change without

notice.

The user's attention is called to the possibility that compliance with this standard may require use of copyrighted

material or of an invention covered by patent rights. By publication of this standard, SEMI takes no position

respecting the validity of any patent rights or copyrights asserted in connection with any item mentioned in this

standard. Users of this standard are expressly advised that determination of any such patent rights or copyrights, and

the risk of infringement of such rights, are entirely their own responsibility.

International), 3081 Zanker Road, San Jose, CA 95134. Reproduction o

the contents in whole or in part is forbidden without express written

consent of SEMI.

SEMI M25-95 © SEMI 1995, 2003 1

SEMI M25-95 (Withdrawn 1103)

SPECIFICATION FOR SILICON WAFERS FOR CALIBRATION OF

LIGHT POINT DEFECT WAFER INSPECTION SYSTEMS WITH

RESPECT TO THE DIAMETER OF POLYSTYRENE LATEX SPHERES

NOTICE: This document was balloted and approved

for withdrawal in 2003.

1 Purpose

1.1 This document describes the specifications to be

met by bare silicon wafers used for calibrating surface

inspection systems with respect to the diameter of

polystyrene latex spheres. This document does not

intend to establish manufacturing procedures for

calibration wafers.

Note 1: This specification might be used as the basis for

making calibration substrates with other materials and/or

surfaces.

2 Scope

2.1 Bare silicon wafers on which latex-spheres of a

known diameter are deposited are used as standards for

the calibration of bare wafer inspection systems. The

response curve of the systems is generated for the

calibration of the systems with respect to the sizing of

polystyrene latex (PSL) spheres, not for counting them.

3 Referenced Documents

3.1 SEMI Standard

SEMI M1 — Specifications for Polished

Monocrystalline Silicon Wafers

4 Terminology

4.1 Light-Point Defect (LPD) — An isolated, localized

effect on the wafer surface or in the substrate wafers

resulting in increased light scattering intensity above a

threshold (unit LSE).

Note 2: LPD is a general term and it includes for example

latex spheres and other localized surface irregularities.

4.2 Latex-Sphere Equivalent (LSE) — The size unit of

an LPD expressed as the diameter of a latex-sphere

which scatters the same amount of light as the LPD.

This is indicated by adding “LSE” to the length unit

used, e.g., 0.2 µ m LSE.

Note 3: Sizing may be different for other materials and shapes

than PSL spheres because of the different optical designs of

inspection systems.

4.3 Response Curve (RC) — The relation between

measured scattered light intensity and latex-sphere

diameters for a calibration surface inspection system.

The RC depends on the light source used and may

contain non-monotonic regions.

4.4 LPD histogram — The distribution of the counts of

LPD’s per unit length over their size as expressed in

LSE.

5 Requirements

5.1 Substrates — The wafers used as substrates for the

deposition of latex-spheres must be bare silicon with a

native oxide surface and they have to meet the

requirements of SEMI M1. In addition to the M1

specification, the surface conditions (for example,

roughness) must be in compliance with Section 5.5.2.

Note 4: The substrate wafer must be measured before latex

sphere deposition with the same type of instrument to ensure

that the conditions of 5.5.2 are fulfilled.

5.2 Latex-Spheres — The latex-spheres used must be

certified with respect to their diameter and they must be

traceable to the Standard Reference Materials (SRM) of

the National Institute of Standards and Technology

(NIST), former National Bureau of Standards (NBS).

The certification methodology must be in accordance

with the technologies used by NIST.

Note 5 : If the PSL are not traceable to NIST, the certification

method should be fully documented.

5.3 Range of Latex-Sphere Diameters — The diameters

of the latex-spheres used for calibration must be

selected so that the measurement range for the intended

application is covered. Sufficient latex-sphere

diameters must be used to achieve the required

accuracy of the RC.

Note 6: For surface inspection systems using laser light

source(s), it is recommended to avoid latex-sphere diameters

corresponding approximately to the wavelength of the laser

used and its multiples of the laser used.

5.4 Density of Latex-Spheres Deposited — The density

of the deposited latex-spheres, full or partial wafer

coverage, must be selected in such a way that the peak

of the histogram of the latex-sphere diameters is at least

100% above the background counts. It has to be

verified that the indicated (relevant) peak in the

histogram is generated by single, isolated latex-spheres

of the specified diameter. A density of 5–15 latex-

spheres per square centimeter is recommended.

5.5 Background Contamination

SEMI M25-95 © SEMI 1995, 2003 2

5.5.1 Calibration wafers must be handled and stored

with great care to avoid contamination and damage.

5.5.2 The bell-shaped peak in the LPD histogram of a

calibration wafer which is generated by the latex-

spheres must be well-defined and must be well above

the background level. The bell-shaped curve has to go

down to less than 50% of its peak value on both sides of

the maximum within a diameter range of ± 15% as

referred to the nominal latex-sphere diameter.

5.6 Multiple Deposition of Latex-Spheres —

Deposition of latex-spheres with different, well-defined

diameters on a calibration wafer is allowed if all the

conditions of this specification are met for each kind of

deposited latex-sphere size.

6 Packaging

6.1 Special packing requirements shall be subject to

agreement between the supplier and the purchaser.

Otherwise all wafers shall be handled, inspected, and

packed in such a manner as to avoid chipping,

scratches, and contamination, and in accordance with

the best industry practices to provide ample protection

against damage during shipment.

7 Data to Accompany Calibration Wafers

7.1 Certificate for average and standard deviation of

the diameter of the latex spheres used, including the

production lot number of latex-spheres used.

7.2 Date of production and certification of calibration

wafer.

7.3 Histogram, as defined above.

7.4 Approximate number of deposited latex-spheres in

a specified area.

7.5 Wafer identification.

7.6 Name and address of the originator of the

calibration wafers.

7.7 LPD’s wafer map.

NOTICE: These standards do not purport to address

safety issues, if any, associated with their use. It is the

responsibility of the user of these standards to establish

appropriate safety and health practices and determine

the applicability of regulatory limitations prior to use.

SEMI makes no warranties or representations as to the

suitability of the standards set forth herein for any

particular application. The determination of the

suitability of the standard is solely the responsibility of

the user. Users are cautioned to refer to manufacturer’s

instructions, product labels, product data sheets, and

other relevant literature respecting any materials

mentioned herein. These standards are subject to

change without notice.

The user’s attention is called to the possibility that

compliance with this standard may require use of

copyrighted material or of an invention covered by

patent rights. By publication of this standard, SEMI

takes no position respecting the validity of any patent

rights or copyrights asserted in connection with any

item mentioned in this standard. Users of this standard

are expressly advised that determination of any such

patent rights or copyrights, and the risk of infringement

of such rights, are entirely their own responsibility.

International), 3081 Zanker Road, San Jose, CA 95134. Reproduction o

the contents in whole or in part is forbidden without express written

consent of SEMI.