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SEMI M43-0301 © SE MI 2001 3 6.4.3.2 T abular Representation by % A r e a Sorted — Specify a threshold T for each D and report th e % area. 6.4.3.3 T abular Representation by Thr e s ho ld — Specify a % area for each D a…

SEMI M43-0301 © SEMI 2001 2

as bow, warp and sori). This filtering may affect the

reported results.

3.3 Nanotopography characterization does not include

microroughness, which applies to a shorter spatial

wavelength range.

3.4 The location of defective areas as calculated in

section 6 may not coincide with the location of the

surface features that lead to those values. This may

cause lack of spatial correlation between reported

defective areas and device process defect areas.

3.5 The height map used to create nanotopography

reports may be affected by wafer shape and

measurement chuck effects.

4 Referenced Standards

4.1 SEMI Standards

SEMI M1  Specification for Monocrystalline

Polished Silicon Wafers

NOTE 1: As listed or revised, all documents cited shall be the

latest publications of adopted standards.

5 Terminology

5.1 fixed quality area (FQA) [SEMI M1] — the

central area of a wafer surface, defined by a nominal

edge exclusion, X over which the specified values of a

parameter apply.

Discussion: The boundary of the FQA is at all points

the distance X away from the periphery of a wafer of

nominal dimensions. (See Figure 1). The size of the

FQA is independent of the wafer diameter and flat

length tolerances. For the purpose of defining the FQA,

the wafer periphery at locations with notch fiducials is

assumed to follow the circumference of a circle with

diameter equal to the nominal wafer diameter.

5.2 nanotopography, of a wafer su rface — the non-

planar deviation of a surface within a spatial

wavelength range of approximately 0.2 to 20 mm.

5.3 nanotopology, of a wafer surface — see

nanotopography.

5.4 roughness [SEMI M1] — the more narrowly

spaced components of surface texture.

Discussion: These components are considered within

defined limits of spatial wavelength (or frequency).

5.5 spatial wavelength — the spacing between

adjacent peaks of a purely sinusoidal profile.

6 Measurements

6.1 The height map is obtained from a front-surface

measurement. An explicit reference plane is not used

for calculating and assigning values.

NOTE 2: Other methods of analyzing nanotopography may

require the use of an explicit reference plane.

6.2 The high-pass filter removes long spatial

wavelength wafer tilt and topography effects,

effectively creating a global reference surface.

6.3 Calculation — The calculation determines the

peak to valley height (P-V) variation among the pixels

included in the analysis area, and assigns that variation

in nanometers to the center of the analysis area. The

calculation is performed for every analysis area within

the FQA of the wafer. These calculations may be

repeated for analysis areas of different dimension D.

NOTE 3: This calculation describes the “full-analysis area”

method. There is another calculation, the “partial analysis

area” method, where the calculation is performed for every

analysis area whose center pixel is within the FQA of the

wafer. The partial analysis area method, not defined in this

document, is being addressed by SEMI for inclusion in a

standard.

6.4 The following measurement elements should be

reported:

6.4.1 Filtering

a) Spatial cutoff of high pass filter

b) Type of Filter

c) Pixel spacing

Filtering is used to remove long wavelength shape

components from the raw height data.

6.4.2 Analysis Area — Specify this analysis area’s:

a) Shape, e.g., square, circle, and

b) Dimension D of the analysis area

An analysis area contains a pixel at its center (Figure

1). The pixels within the surrounding analysis area of

dimension D, and within the FQA, are used to deter-

mine the value assigned to the center pixel location.

6.4.3 Data Report — Report one or more of the

following:

6.4.3.1 Statistical Representation by Threshold Curve

— Plot, for each D, % area vs. threshold T, in

nanometers, where % area is the ratio of

a) the number of analysis areas whose assigned value

(calculated per Section 6.3) exceeds the threshold

T, to

b) the number of pixels within the FQA.

The ratio is expressed as a percentage.

SEMI M43-0301 © SEMI 20013

6.4.3.2 Tabular Representation by % Area Sorted — Specify a threshold T for each D and report the % area.

6.4.3.3 Tabular Representation by Threshold — Specify a % area for each D and report the Threshold, T.

6.4.3.4 Spatial Representation by Height Map — Generate a whole wafer height map of the surface.

6.4.3.5 Spatial Representation by Defect Map — Generate a whole wafer height map of the surface. Analysis areas

whose assigned values (calculated per Section 6.3) exceed the threshold in Section 6.4.3.2 are flagged for each D.

6.4.3.6 Spatial Representation by PV Analysis Map — Generate a whole wafer map of the values assigned in

Section 6.3.

Pixel grid center lines

Center pixel, included

Included pixels

Included pixels, square

Pixel grid center lines

Center pixel, included

Included pixels

Included pixels, square

Figure 1

The Analysis Area Of Dimension D, Center And Included Pixels Are Indicated

NOTICE: SEMI makes no warranties or representations as to the suitability of the standard 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.

RELATED INFORMATION 1

NOTE: This related information is not an official part of SEMI M43 and is not intended to modify or supercede the proposed

standard. It is provided for information purposes. The proposed standard should be referred to in all cases.

R1-1 SEMI M43 describes reporting wafer nanotopography. The figure below illustrates the flow of data from

measurement through reporting referenced to the document sections.

Height Map

(6.1)

Filtered

Height Map

(6.2)

PV Analysis

Map (6.3)

Threshold Curve (6.4.3.1)

% Area Sorted (6.4.3.2)

Threshold @ % Area (6.4.3.3)

Height Map (6.4.3.4)

Defect Map (6.4.3.5)

PV Analysis Map (6.4.3.6)

1. Acquire Data

2. High Pass Filter

3. Perform Calculation

(for each dimension D)

4. Report Results

Figure R1-1

Nanotopography Reporting Flow