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SEMI M1-0305 © SEMI 1978, 2005 45 R2-2.3 JEI TA ( formerly JEIDA ) Stan dard 2 EM-3505 — H eight Calibration i n 1 nm Order for AFM R2-2.4 DIN Standard s 4 50430 — Measurement of the Electrical Resistivity of Silic on or…

SEMI M1-0305 © SEMI 1978, 2005 44

RELATED INFORMATION 2

TEST METHODS

NOTICE: This related information is not an official part of SEMI M1 and is not intended to modify or supersede

the official standard. This information was developed during the revision of this standard in 2004. It is based in part

on information previously published as part of SEMI M28, withdrawn in October 2000. Approval was by full letter

ballot procedures with publication authorized by the NA Regional Standards Committee on November 4, 2004.

Determination of the suitability of the material is solely the responsibility of the user.

R2-1 Scope

R2-1.1 This Related Information Section discusses aspects of the various test methods listed in Table 1 together

with additional information about other test methods that are not listed in Table 1 but either have been or still are

used in the industry.

R2-1.2 The next section contains references to the test methods that are not cited in the main body of SEMI M1 but

that are discussed here. The various test methods are discussed in order that the items they cover are listed in Table

R2-1.3 Note that silicon wafers are extremely fragile. While the mechanical dimensions of a wafer can be

measured by use of tools such as micrometer calipers and other conventional techniques, the wafer may be damaged

physically in ways that are not immediately evident. Special care must, therefore, be used in the selection and

execution of measurement methods.

NOTICE: This section does not purport to address safety issues, if any, associated with its use. It is the

responsibility of the user of this standard to establish appropriate safety and health practices and determine the

applicability of regulatory or other limitations prior to use.

R2-2 Referenced Standards

R2-2.1 The standards listed in this section are referenced only in this related information. See Section 4 for other

standards that are referenced in this related information.

R2-2.2 SEMI Standards

SEMI M49 — Guide for Specifying Geometry Measurement Equipment for Silicon Wafers for the 130 nm

Technology Generation

SEMI M50 — Test Method for Determining Capture Rate and False Count Rate for Surface Scanning Inspection

Systems by the Overlay Method

SEMI M52 — Guide for Specifying Scanning Surface Inspection Systems for Silicon Wafers for the 130 nm

Technology Generation

SEMI MF43 — Test Methods for Resistivity of Semiconductor Materials

SEMI MF154 — Guide for Identification of Structures and Contaminants Seen on Specular Silicon Surfaces

SEMI MF398 — Test Method for Majority Carrier Concentration in Semiconductors by Measurement of

Wavenumber or Wavelength of the Plasma Resonance Minimum

SEMI MF723 — Practice for Conversion Between Resistivity and Dopant Density for Boron-Doped, Phosphorus-

Doped, and Arsenic-Doped Silicon.

SEMI MF1527 — Guide for Application of Silicon Certified Reference Materials and Reference Wafers for

Calibration and Control of Instruments for Measuring Resistivity of Silicon

SEMI MF1529 — Test Method for Sheet Resistance Uniformity Evaluation by In-Line Four-Point Probe with the

Dual-Configuration Procedure

SEMI MF1618 — Practice for Determination of Uniformity of Thin Films on Silicon Wafers

SEMI MF1810 — Test Method for Counting Preferentailly Etched or Decorated Structural Defects on Silicon

Wafers

SEMI M1-0305 © SEMI 1978, 2005 45

R2-2.3 JEITA (formerly JEIDA) Standard

EM-3505 — Height Calibration in 1 nm Order for AFM

R2-2.4 DIN Standards

50430 — Measurement of the Electrical Resistivity of Silicon or Germanium Single Crystals in Bars by Means of

the Two-point-probe Direct Current Method

50444 — Conversion Between Resistivity and Dopant Density; Silicon

R2-2.5 ANSI Standard

ANSI/ASME B46.1 — Surface Texture (Surface Roughness, Waviness, and Lay)

R2-2.6 ISO Standards

ISO 4287/1 — Surface Roughness – Terminology – Part 1: Surface and its Parameters

ISO 14644/1 — Clean Room and Associated Controlled Environments — Classification of Air Cleanliness

NOTICE: Unless otherwise indicated, all documents cited shall be the latest published versions.

R2-3 General Characteristics

R2-3.1 Crystal Orientation—The crystallographic orientation of the source crystal can be determined by the x-ray

methods of SEMI MF26, JEITA EM-3501, or DIN 50433/1, the optical method of SEMI MF26 or DIN 50433/2, or

the Laue method of DIN 50433/3. X-ray methods are most commonly used by wafer suppliers.

{Need some

discussion here about differences between MF26 and EM-3501}}

R2-3.2 Conductivity Type—One of the five methods of SEMI MF42, one of the methods of JIS H 0607, or one of

the four methods of DIN 50432 should be used to determine conductivity type. This quantity is generally well

controlled by silicon wafer suppliers and is not usually verified on incoming.

R2-3.3 Many of these tests need to be carried out in cleanroom environments of ISO Class 4, 5, or 6 depending on

the cleanliness requirements. These classes are defined in ISO 14664-1.

R2-4 Electrical Characteristics

R2-4.1 Resistivity of wafers is most appropriately determined for referee purposes by SEMI MF84 or DIN 50431.

Under some circumstances these tests may be considered destructive, and an alternative means may be required.

One nondestructive test is SEMI MF673, having a range from 0.0001 to 100 ·cm. Another nondestructive test is

SEMI MF398, which is limited to carrier concentrations in the ranges from 1.5 × 10

to 1.5 × 10

3

for n-type

silicon and from 3 × 10

to 5 × 10

3

for p-type silicon, and has only moderate inter-laboratory precision. Other

older methods that require a bar-shaped test specimen include SEMI MF43 and DIN 50430; these methods are no

longer in general use. It is also possible to establish the dopant density from room temperature measurements in

silicon using SEMI MF723 (for boron, phosphorus, or arsenic doped silicon) or DIN 50444 (for boron and

phosphorus doped silicon only). SEMI MF1527 is a useful standard in describing ways of ensuring that resistivity

measuring instruments are performing correctly.

R2-4.2 Radial Resistivity Variation is generally determined by SEMI MF81 or DIN 50435. These test methods use

several different measurement positions so the desired position must be specified. It is also possible to measure the

resistivity in one of the circular patterns specified in SEMI MF1618 using SEMI MF1529 as the resistivity

measurement method.

R2-4.3 Resistivity Striations can generally be viewed visually using one of the techniques discussed in Section R2-

9. For an electrical measurement, spreading resistance (SEMI MF525) is generally employed but this is strictly an

off-line measurement.

R2-4.4 Minority Carrier Lifetime can be measured by a number of methods. The photoconductive decay methods

(SEMI MF28, JIS H 0604, and DIN 50440/1 all require the use of special test specimens; Microwave reflectivity

measurements (SEMI MF1535 and JEITA EM-3502) are applicable to measurements on wafers, but special surface

passivation procedures may be required to obtain meaningful results. Minority carrier lifetime may also be inferred

from measurements made in accordance with SEMI MF1388, which yields generation lifetime if the measurements

SEMI M1-0305 © SEMI 1978, 2005 46

are made at room temperature and recombination lifetime if they are made at elevated temperature (50 to 75C).

The test specimens required for this test method can be made by procedures compatible with typical wafer

processing.

R2-5 Chemical Characteristics

R2-5.1 Oxygen Concentration in relatively high resistivity specimens (



> 1 to 3 ·cm at room temperature) should

be measured by infrared techniques. SEMI MF1188, JEITA EM-3504, and DIN 50438 all utilize approximately

normal incidence illumination and the IOC-88 calibration factor to determine the interstitial oxygen content. See

SEMI M44 for a discussion of other calibration factors and their relationship to IOC-88. SEMI MF1619 uses p-

polarized radiation, incident at the Brewster angle to reduce the multiple reflections from polished wafers. For more

heavily doped wafers, secondary ion mass spectrometry (SIMS, SEMI MF1366) and gas fusion analysis (GFA) can

be used to determine total oxygen content. There is no standardized method for performing GFA, and the

repeatability of this technique is generally poorer than SIMS.

R2-5.2 Radial Oxygen Variation should be determined by measuring the oxygen content by one of the above

methods at selected locations on the wafer defined in SEMI MF951. Usually measurements are made at the center

and at a single point on the primary flat or notch bisector 10 mm from the edge of the wafer opposite the fiducial;

this is known as test plan A-1.

R2-5.3 Carbon Concentration should be measured by SEMI MF1391, JEITA 56, and DIN 50438/2. The most

modern calibration coefficients are used in SEMI MF1391 and JEITA 56. For these methods, the test specimen

cannot be too heavily doped, and special thick test specimens may be necessary.

R2-5.4 Boron Contamination in heavily doped n-type silicon can be determined by SEMI MF1528.

R2-6 Structural Characteristics

R2-6.1 Dislocation Etch Pit Density, Slip, Lineage, Twins, and Swirl are usually displayed by etching and visual or

microscopic observation. JIS H 0609 is a comprehensive test method for carrying out this procedure with the use of

non-chromic etchants. SEMI MF1809 also recommends non-chromic etchants for this test. For the full procedure,

SEMI MF1809 must be used with other standards including SEMI MF1726 and SEMI MF1810. DIN 50434 is an

older, but comprehensive test procedure to observe these and other structural defects based on chrome-containing

etchants. It is also possible to observe these defects by x-ray topography using DIN 50443/1.

R2-6.2 Shallow Pits can be exposed by the relatively low temperature heating cycle and procedures in SEMI

MF1049 if they are present in sufficient density, but testing for shallow pits in production environments is usually

carried out using the temperature cycle in SEMI MF1727 followed by etching with etchants discussed in SEMI

MF1809, examination by SEMI MF1726, and counting by SEMI MF1810. They can also be observed by using JIS

H 0609.

R2-6.3 Oxidation Induced Stacking Faults (OISF) can be observed by using JIS H 0609, or by using the

temperature cycle in SEMI MF1727 followed by etching with etchants discussed in SEMI MF1809, examination by

SEMI MF1726, and counting by SEMI MF1810. OISF can also be observed by x-ray topography using DIN

50443/1 following thermal treatment according to JIS H 0609 or SEMI MF1727.

R2-6.4 Oxide Precipitates (Bulk Micro Defects, BMD) are generated with the use of a temperature cycle such as

those in SEMI MF1239. The amount of precipitation can be measured by the oxygen reduction method of SEMI

MF1239 or by direct observation by infrared that has not yet been standardized.

R2-6.5 Bulk Defects can be detected by x-ray topography in accordance with DIN 50443/1.

R2.7 Dimensional Characteristics

R2-7.1 Diameter is presently very well controlled in silicon wafers that have been edge profiled with cam follower

equipment. For three-point measurements at locations defined by SEMI MF2074 and, except for positions on 150

mm diameter, n-type (100) wafers, by DIN 50441/4. The latter utilizes a measuring or projection microscope to

make the diameter measurements, but the former allows a dial gauge or any other equally accurate method of

dimensional measurement.